diff options
| author |   David Seifert <soap@gentoo.org> | 2020-09-25 09:00:00 +0000 |
|---|---|---|
| committer | David Seifert <soap@gentoo.org> | 2020-09-25 09:00:00 +0000 |
| commit | c521ae3cfdbcfee0b925d69037926faeeae1228c (patch) | |
| tree | 56644c42d2166358369370d330bdacfea53b0cd4 | |
| download | lua-patches-c521ae3cfdbcfee0b925d69037926faeeae1228c.tar.gz lua-patches-c521ae3cfdbcfee0b925d69037926faeeae1228c.tar.bz2 lua-patches-c521ae3cfdbcfee0b925d69037926faeeae1228c.zip | |
Add upstream 5.3.6
Signed-off-by: David Seifert <soap@gentoo.org>
| -rw-r--r-- | Makefile | 114 | ||||
| -rw-r--r-- | README | 6 | ||||
| -rw-r--r-- | doc/contents.html | 650 | ||||
| -rw-r--r-- | doc/index.css | 21 | ||||
| -rw-r--r-- | doc/logo.gif | bin | 0 -> 9893 bytes | |||
| -rw-r--r-- | doc/lua.1 | 112 | ||||
| -rw-r--r-- | doc/lua.css | 161 | ||||
| -rw-r--r-- | doc/luac.1 | 118 | ||||
| -rw-r--r-- | doc/manual.css | 21 | ||||
| -rw-r--r-- | doc/manual.html | 10982 | ||||
| -rw-r--r-- | doc/osi-certified-72x60.png | bin | 0 -> 3774 bytes | |||
| -rw-r--r-- | doc/readme.html | 365 | ||||
| -rw-r--r-- | src/Makefile | 197 | ||||
| -rw-r--r-- | src/lapi.c | 1299 | ||||
| -rw-r--r-- | src/lapi.h | 24 | ||||
| -rw-r--r-- | src/lauxlib.c | 1048 | ||||
| -rw-r--r-- | src/lauxlib.h | 264 | ||||
| -rw-r--r-- | src/lbaselib.c | 498 | ||||
| -rw-r--r-- | src/lbitlib.c | 233 | ||||
| -rw-r--r-- | src/lcode.c | 1203 | ||||
| -rw-r--r-- | src/lcode.h | 88 | ||||
| -rw-r--r-- | src/lcorolib.c | 168 | ||||
| -rw-r--r-- | src/lctype.c | 55 | ||||
| -rw-r--r-- | src/lctype.h | 95 | ||||
| -rw-r--r-- | src/ldblib.c | 456 | ||||
| -rw-r--r-- | src/ldebug.c | 700 | ||||
| -rw-r--r-- | src/ldebug.h | 39 | ||||
| -rw-r--r-- | src/ldo.c | 802 | ||||
| -rw-r--r-- | src/ldo.h | 58 | ||||
| -rw-r--r-- | src/ldump.c | 215 | ||||
| -rw-r--r-- | src/lfunc.c | 151 | ||||
| -rw-r--r-- | src/lfunc.h | 61 | ||||
| -rw-r--r-- | src/lgc.c | 1179 | ||||
| -rw-r--r-- | src/lgc.h | 147 | ||||
| -rw-r--r-- | src/linit.c | 68 | ||||
| -rw-r--r-- | src/liolib.c | 778 | ||||
| -rw-r--r-- | src/llex.c | 568 | ||||
| -rw-r--r-- | src/llex.h | 85 | ||||
| -rw-r--r-- | src/llimits.h | 323 | ||||
| -rw-r--r-- | src/lmathlib.c | 410 | ||||
| -rw-r--r-- | src/lmem.c | 100 | ||||
| -rw-r--r-- | src/lmem.h | 69 | ||||
| -rw-r--r-- | src/loadlib.c | 790 | ||||
| -rw-r--r-- | src/lobject.c | 522 | ||||
| -rw-r--r-- | src/lobject.h | 549 | ||||
| -rw-r--r-- | src/lopcodes.c | 124 | ||||
| -rw-r--r-- | src/lopcodes.h | 297 | ||||
| -rw-r--r-- | src/loslib.c | 409 | ||||
| -rw-r--r-- | src/lparser.c | 1653 | ||||
| -rw-r--r-- | src/lparser.h | 133 | ||||
| -rw-r--r-- | src/lprefix.h | 45 | ||||
| -rw-r--r-- | src/lstate.c | 347 | ||||
| -rw-r--r-- | src/lstate.h | 253 | ||||
| -rw-r--r-- | src/lstring.c | 248 | ||||
| -rw-r--r-- | src/lstring.h | 49 | ||||
| -rw-r--r-- | src/lstrlib.c | 1584 | ||||
| -rw-r--r-- | src/ltable.c | 688 | ||||
| -rw-r--r-- | src/ltable.h | 66 | ||||
| -rw-r--r-- | src/ltablib.c | 450 | ||||
| -rw-r--r-- | src/ltm.c | 165 | ||||
| -rw-r--r-- | src/ltm.h | 76 | ||||
| -rw-r--r-- | src/lua.c | 612 | ||||
| -rw-r--r-- | src/lua.h | 485 | ||||
| -rw-r--r-- | src/lua.hpp | 9 | ||||
| -rw-r--r-- | src/luac.c | 450 | ||||
| -rw-r--r-- | src/luaconf.h | 790 | ||||
| -rw-r--r-- | src/lualib.h | 61 | ||||
| -rw-r--r-- | src/lundump.c | 287 | ||||
| -rw-r--r-- | src/lundump.h | 32 | ||||
| -rw-r--r-- | src/lutf8lib.c | 256 | ||||
| -rw-r--r-- | src/lvm.c | 1322 | ||||
| -rw-r--r-- | src/lvm.h | 113 | ||||
| -rw-r--r-- | src/lzio.c | 68 | ||||
| -rw-r--r-- | src/lzio.h | 66 |
74 files changed, 36930 insertions, 0 deletions
diff --git a/Makefile b/Makefile new file mode 100644 index 0000000..a2820e0 --- /dev/null +++ b/Makefile @@ -0,0 +1,114 @@ +# Makefile for installing Lua +# See doc/readme.html for installation and customization instructions. + +# == CHANGE THE SETTINGS BELOW TO SUIT YOUR ENVIRONMENT ======================= + +# Your platform. See PLATS for possible values. +PLAT= none + +# Where to install. The installation starts in the src and doc directories, +# so take care if INSTALL_TOP is not an absolute path. See the local target. +# You may want to make INSTALL_LMOD and INSTALL_CMOD consistent with +# LUA_ROOT, LUA_LDIR, and LUA_CDIR in luaconf.h. +INSTALL_TOP= /usr/local +INSTALL_BIN= $(INSTALL_TOP)/bin +INSTALL_INC= $(INSTALL_TOP)/include +INSTALL_LIB= $(INSTALL_TOP)/lib +INSTALL_MAN= $(INSTALL_TOP)/man/man1 +INSTALL_LMOD= $(INSTALL_TOP)/share/lua/$V +INSTALL_CMOD= $(INSTALL_TOP)/lib/lua/$V + +# How to install. If your install program does not support "-p", then +# you may have to run ranlib on the installed liblua.a. +INSTALL= install -p +INSTALL_EXEC= $(INSTALL) -m 0755 +INSTALL_DATA= $(INSTALL) -m 0644 +# +# If you don't have "install" you can use "cp" instead. +# INSTALL= cp -p +# INSTALL_EXEC= $(INSTALL) +# INSTALL_DATA= $(INSTALL) + +# Other utilities. +MKDIR= mkdir -p +RM= rm -f + +# == END OF USER SETTINGS -- NO NEED TO CHANGE ANYTHING BELOW THIS LINE ======= + +# Convenience platforms targets. +PLATS= aix bsd c89 freebsd generic linux macosx mingw posix solaris + +# What to install. +TO_BIN= lua luac +TO_INC= lua.h luaconf.h lualib.h lauxlib.h lua.hpp +TO_LIB= liblua.a +TO_MAN= lua.1 luac.1 + +# Lua version and release. +V= 5.3 +R= $V.6 + +# Targets start here. +all: $(PLAT) + +$(PLATS) clean: + cd src && $(MAKE) $@ + +test: dummy + src/lua -v + +install: dummy + cd src && $(MKDIR) $(INSTALL_BIN) $(INSTALL_INC) $(INSTALL_LIB) $(INSTALL_MAN) $(INSTALL_LMOD) $(INSTALL_CMOD) + cd src && $(INSTALL_EXEC) $(TO_BIN) $(INSTALL_BIN) + cd src && $(INSTALL_DATA) $(TO_INC) $(INSTALL_INC) + cd src && $(INSTALL_DATA) $(TO_LIB) $(INSTALL_LIB) + cd doc && $(INSTALL_DATA) $(TO_MAN) $(INSTALL_MAN) + +uninstall: + cd src && cd $(INSTALL_BIN) && $(RM) $(TO_BIN) + cd src && cd $(INSTALL_INC) && $(RM) $(TO_INC) + cd src && cd $(INSTALL_LIB) && $(RM) $(TO_LIB) + cd doc && cd $(INSTALL_MAN) && $(RM) $(TO_MAN) + +local: + $(MAKE) install INSTALL_TOP=../install + +none: + @echo "Please do 'make PLATFORM' where PLATFORM is one of these:" + @echo " $(PLATS)" + @echo "See doc/readme.html for complete instructions." + +# make may get confused with test/ and install/ +dummy: + +# echo config parameters +echo: + @cd src && $(MAKE) -s echo + @echo "PLAT= $(PLAT)" + @echo "V= $V" + @echo "R= $R" + @echo "TO_BIN= $(TO_BIN)" + @echo "TO_INC= $(TO_INC)" + @echo "TO_LIB= $(TO_LIB)" + @echo "TO_MAN= $(TO_MAN)" + @echo "INSTALL_TOP= $(INSTALL_TOP)" + @echo "INSTALL_BIN= $(INSTALL_BIN)" + @echo "INSTALL_INC= $(INSTALL_INC)" + @echo "INSTALL_LIB= $(INSTALL_LIB)" + @echo "INSTALL_MAN= $(INSTALL_MAN)" + @echo "INSTALL_LMOD= $(INSTALL_LMOD)" + @echo "INSTALL_CMOD= $(INSTALL_CMOD)" + @echo "INSTALL_EXEC= $(INSTALL_EXEC)" + @echo "INSTALL_DATA= $(INSTALL_DATA)" + +# echo pkg-config data +pc: + @echo "version=$R" + @echo "prefix=$(INSTALL_TOP)" + @echo "libdir=$(INSTALL_LIB)" + @echo "includedir=$(INSTALL_INC)" + +# list targets that do not create files (but not all makes understand .PHONY) +.PHONY: all $(PLATS) clean test install local none dummy echo pecho lecho + +# (end of Makefile) @@ -0,0 +1,6 @@ + +This is Lua 5.3.6, released on 14 Sep 2020. + +For installation instructions, license details, and +further information about Lua, see doc/readme.html. + diff --git a/doc/contents.html b/doc/contents.html new file mode 100644 index 0000000..3a357b1 --- /dev/null +++ b/doc/contents.html @@ -0,0 +1,650 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> +<HTML> +<HEAD> +<TITLE>Lua 5.3 Reference Manual - contents</TITLE> +<LINK REL="stylesheet" TYPE="text/css" HREF="lua.css"> +<LINK REL="stylesheet" TYPE="text/css" HREF="index.css"> +<META HTTP-EQUIV="content-type" CONTENT="text/html; charset=iso-8859-1"> +</HEAD> + +<BODY> + +<H1> +<A HREF="http://www.lua.org/"><IMG SRC="logo.gif" ALT="Lua"></A> +Lua 5.3 Reference Manual +</H1> + +<P> +The reference manual is the official definition of the Lua language. +<BR> +For a complete introduction to Lua programming, see the book +<A HREF="http://www.lua.org/pil/">Programming in Lua</A>. + +<DIV CLASS="menubar"> +<A HREF="manual.html">start</A> +· +<A HREF="#contents">contents</A> +· +<A HREF="#index">index</A> +· +<A HREF="http://www.lua.org/manual/">other versions</A> +</DIV> + +<P> +<SMALL> +Copyright © 2015–2020 Lua.org, PUC-Rio. +Freely available under the terms of the +<A HREF="http://www.lua.org/license.html">Lua license</A>. +</SMALL> + +<H2><A NAME="contents">Contents</A></H2> +<UL CLASS="contents menubar"> +<LI><A HREF="manual.html">1 – Introduction</A> +<P> +<LI><A HREF="manual.html#2">2 – Basic Concepts</A> +<UL> +<LI><A HREF="manual.html#2.1">2.1 – Values and Types</A> +<LI><A HREF="manual.html#2.2">2.2 – Environments and the Global Environment</A> +<LI><A HREF="manual.html#2.3">2.3 – Error Handling</A> +<LI><A HREF="manual.html#2.4">2.4 – Metatables and Metamethods</A> +<LI><A HREF="manual.html#2.5">2.5 – Garbage Collection</A> +<UL> +<LI><A HREF="manual.html#2.5.1">2.5.1 – Garbage-Collection Metamethods</A> +<LI><A HREF="manual.html#2.5.2">2.5.2 – Weak Tables</A> +</UL> +<LI><A HREF="manual.html#2.6">2.6 – Coroutines</A> +</UL> +<P> +<LI><A HREF="manual.html#3">3 – The Language</A> +<UL> +<LI><A HREF="manual.html#3.1">3.1 – Lexical Conventions</A> +<LI><A HREF="manual.html#3.2">3.2 – Variables</A> +<LI><A HREF="manual.html#3.3">3.3 – Statements</A> +<UL> +<LI><A HREF="manual.html#3.3.1">3.3.1 – Blocks</A> +<LI><A HREF="manual.html#3.3.2">3.3.2 – Chunks</A> +<LI><A HREF="manual.html#3.3.3">3.3.3 – Assignment</A> +<LI><A HREF="manual.html#3.3.4">3.3.4 – Control Structures</A> +<LI><A HREF="manual.html#3.3.5">3.3.5 – For Statement</A> +<LI><A HREF="manual.html#3.3.6">3.3.6 – Function Calls as Statements</A> +<LI><A HREF="manual.html#3.3.7">3.3.7 – Local Declarations</A> +</UL> +<LI><A HREF="manual.html#3.4">3.4 – Expressions</A> +<UL> +<LI><A HREF="manual.html#3.4.1">3.4.1 – Arithmetic Operators</A> +<LI><A HREF="manual.html#3.4.2">3.4.2 – Bitwise Operators</A> +<LI><A HREF="manual.html#3.4.3">3.4.3 – Coercions and Conversions</A> +<LI><A HREF="manual.html#3.4.4">3.4.4 – Relational Operators</A> +<LI><A HREF="manual.html#3.4.5">3.4.5 – Logical Operators</A> +<LI><A HREF="manual.html#3.4.6">3.4.6 – Concatenation</A> +<LI><A HREF="manual.html#3.4.7">3.4.7 – The Length Operator</A> +<LI><A HREF="manual.html#3.4.8">3.4.8 – Precedence</A> +<LI><A HREF="manual.html#3.4.9">3.4.9 – Table Constructors</A> +<LI><A HREF="manual.html#3.4.10">3.4.10 – Function Calls</A> +<LI><A HREF="manual.html#3.4.11">3.4.11 – Function Definitions</A> +</UL> +<LI><A HREF="manual.html#3.5">3.5 – Visibility Rules</A> +</UL> +<P> +<LI><A HREF="manual.html#4">4 – The Application Program Interface</A> +<UL> +<LI><A HREF="manual.html#4.1">4.1 – The Stack</A> +<LI><A HREF="manual.html#4.2">4.2 – Stack Size</A> +<LI><A HREF="manual.html#4.3">4.3 – Valid and Acceptable Indices</A> +<LI><A HREF="manual.html#4.4">4.4 – C Closures</A> +<LI><A HREF="manual.html#4.5">4.5 – Registry</A> +<LI><A HREF="manual.html#4.6">4.6 – Error Handling in C</A> +<LI><A HREF="manual.html#4.7">4.7 – Handling Yields in C</A> +<LI><A HREF="manual.html#4.8">4.8 – Functions and Types</A> +<LI><A HREF="manual.html#4.9">4.9 – The Debug Interface</A> +</UL> +<P> +<LI><A HREF="manual.html#5">5 – The Auxiliary Library</A> +<UL> +<LI><A HREF="manual.html#5.1">5.1 – Functions and Types</A> +</UL> +<P> +<LI><A HREF="manual.html#6">6 – Standard Libraries</A> +<UL> +<LI><A HREF="manual.html#6.1">6.1 – Basic Functions</A> +<LI><A HREF="manual.html#6.2">6.2 – Coroutine Manipulation</A> +<LI><A HREF="manual.html#6.3">6.3 – Modules</A> +<LI><A HREF="manual.html#6.4">6.4 – String Manipulation</A> +<UL> +<LI><A HREF="manual.html#6.4.1">6.4.1 – Patterns</A> +<LI><A HREF="manual.html#6.4.2">6.4.2 – Format Strings for Pack and Unpack</A> +</UL> +<LI><A HREF="manual.html#6.5">6.5 – UTF-8 Support</A> +<LI><A HREF="manual.html#6.6">6.6 – Table Manipulation</A> +<LI><A HREF="manual.html#6.7">6.7 – Mathematical Functions</A> +<LI><A HREF="manual.html#6.8">6.8 – Input and Output Facilities</A> +<LI><A HREF="manual.html#6.9">6.9 – Operating System Facilities</A> +<LI><A HREF="manual.html#6.10">6.10 – The Debug Library</A> +</UL> +<P> +<LI><A HREF="manual.html#7">7 – Lua Standalone</A> +<P> +<LI><A HREF="manual.html#8">8 – Incompatibilities with the Previous Version</A> +<UL> +<LI><A HREF="manual.html#8.1">8.1 – Changes in the Language</A> +<LI><A HREF="manual.html#8.2">8.2 – Changes in the Libraries</A> +<LI><A HREF="manual.html#8.3">8.3 – Changes in the API</A> +</UL> +<P> +<LI><A HREF="manual.html#9">9 – The Complete Syntax of Lua</A> +</UL> + +<H2><A NAME="index">Index</A></H2> +<TABLE CLASS="menubar" WIDTH="100%"> +<TR> +<TD> +<H3><A NAME="functions">Lua functions</A></H3> +<P> +<A HREF="manual.html#6.1">basic</A><BR> +<A HREF="manual.html#pdf-_G">_G</A><BR> +<A HREF="manual.html#pdf-_VERSION">_VERSION</A><BR> +<A HREF="manual.html#pdf-assert">assert</A><BR> +<A HREF="manual.html#pdf-collectgarbage">collectgarbage</A><BR> +<A HREF="manual.html#pdf-dofile">dofile</A><BR> +<A HREF="manual.html#pdf-error">error</A><BR> +<A HREF="manual.html#pdf-getmetatable">getmetatable</A><BR> +<A HREF="manual.html#pdf-ipairs">ipairs</A><BR> +<A HREF="manual.html#pdf-load">load</A><BR> +<A HREF="manual.html#pdf-loadfile">loadfile</A><BR> +<A HREF="manual.html#pdf-next">next</A><BR> +<A HREF="manual.html#pdf-pairs">pairs</A><BR> +<A HREF="manual.html#pdf-pcall">pcall</A><BR> +<A HREF="manual.html#pdf-print">print</A><BR> +<A HREF="manual.html#pdf-rawequal">rawequal</A><BR> +<A HREF="manual.html#pdf-rawget">rawget</A><BR> +<A HREF="manual.html#pdf-rawlen">rawlen</A><BR> +<A HREF="manual.html#pdf-rawset">rawset</A><BR> +<A HREF="manual.html#pdf-require">require</A><BR> +<A HREF="manual.html#pdf-select">select</A><BR> +<A HREF="manual.html#pdf-setmetatable">setmetatable</A><BR> +<A HREF="manual.html#pdf-tonumber">tonumber</A><BR> +<A HREF="manual.html#pdf-tostring">tostring</A><BR> +<A HREF="manual.html#pdf-type">type</A><BR> +<A HREF="manual.html#pdf-xpcall">xpcall</A><BR> + +<P> +<A HREF="manual.html#6.2">coroutine</A><BR> +<A HREF="manual.html#pdf-coroutine.create">coroutine.create</A><BR> +<A HREF="manual.html#pdf-coroutine.isyieldable">coroutine.isyieldable</A><BR> +<A HREF="manual.html#pdf-coroutine.resume">coroutine.resume</A><BR> +<A HREF="manual.html#pdf-coroutine.running">coroutine.running</A><BR> +<A HREF="manual.html#pdf-coroutine.status">coroutine.status</A><BR> +<A HREF="manual.html#pdf-coroutine.wrap">coroutine.wrap</A><BR> +<A HREF="manual.html#pdf-coroutine.yield">coroutine.yield</A><BR> + +<P> +<A HREF="manual.html#6.10">debug</A><BR> +<A HREF="manual.html#pdf-debug.debug">debug.debug</A><BR> +<A HREF="manual.html#pdf-debug.gethook">debug.gethook</A><BR> +<A HREF="manual.html#pdf-debug.getinfo">debug.getinfo</A><BR> +<A HREF="manual.html#pdf-debug.getlocal">debug.getlocal</A><BR> +<A HREF="manual.html#pdf-debug.getmetatable">debug.getmetatable</A><BR> +<A HREF="manual.html#pdf-debug.getregistry">debug.getregistry</A><BR> +<A HREF="manual.html#pdf-debug.getupvalue">debug.getupvalue</A><BR> +<A HREF="manual.html#pdf-debug.getuservalue">debug.getuservalue</A><BR> +<A HREF="manual.html#pdf-debug.sethook">debug.sethook</A><BR> +<A HREF="manual.html#pdf-debug.setlocal">debug.setlocal</A><BR> +<A HREF="manual.html#pdf-debug.setmetatable">debug.setmetatable</A><BR> +<A HREF="manual.html#pdf-debug.setupvalue">debug.setupvalue</A><BR> +<A HREF="manual.html#pdf-debug.setuservalue">debug.setuservalue</A><BR> +<A HREF="manual.html#pdf-debug.traceback">debug.traceback</A><BR> +<A HREF="manual.html#pdf-debug.upvalueid">debug.upvalueid</A><BR> +<A HREF="manual.html#pdf-debug.upvaluejoin">debug.upvaluejoin</A><BR> + +<P> +<A HREF="manual.html#6.8">io</A><BR> +<A HREF="manual.html#pdf-io.close">io.close</A><BR> +<A HREF="manual.html#pdf-io.flush">io.flush</A><BR> +<A HREF="manual.html#pdf-io.input">io.input</A><BR> +<A HREF="manual.html#pdf-io.lines">io.lines</A><BR> +<A HREF="manual.html#pdf-io.open">io.open</A><BR> +<A HREF="manual.html#pdf-io.output">io.output</A><BR> +<A HREF="manual.html#pdf-io.popen">io.popen</A><BR> +<A HREF="manual.html#pdf-io.read">io.read</A><BR> +<A HREF="manual.html#pdf-io.stderr">io.stderr</A><BR> +<A HREF="manual.html#pdf-io.stdin">io.stdin</A><BR> +<A HREF="manual.html#pdf-io.stdout">io.stdout</A><BR> +<A HREF="manual.html#pdf-io.tmpfile">io.tmpfile</A><BR> +<A HREF="manual.html#pdf-io.type">io.type</A><BR> +<A HREF="manual.html#pdf-io.write">io.write</A><BR> + +<A HREF="manual.html#pdf-file:close">file:close</A><BR> +<A HREF="manual.html#pdf-file:flush">file:flush</A><BR> +<A HREF="manual.html#pdf-file:lines">file:lines</A><BR> +<A HREF="manual.html#pdf-file:read">file:read</A><BR> +<A HREF="manual.html#pdf-file:seek">file:seek</A><BR> +<A HREF="manual.html#pdf-file:setvbuf">file:setvbuf</A><BR> +<A HREF="manual.html#pdf-file:write">file:write</A><BR> + +</TD> +<TD> +<H3> </H3> +<P> +<A HREF="manual.html#6.7">math</A><BR> +<A HREF="manual.html#pdf-math.abs">math.abs</A><BR> +<A HREF="manual.html#pdf-math.acos">math.acos</A><BR> +<A HREF="manual.html#pdf-math.asin">math.asin</A><BR> +<A HREF="manual.html#pdf-math.atan">math.atan</A><BR> +<A HREF="manual.html#pdf-math.ceil">math.ceil</A><BR> +<A HREF="manual.html#pdf-math.cos">math.cos</A><BR> +<A HREF="manual.html#pdf-math.deg">math.deg</A><BR> +<A HREF="manual.html#pdf-math.exp">math.exp</A><BR> +<A HREF="manual.html#pdf-math.floor">math.floor</A><BR> +<A HREF="manual.html#pdf-math.fmod">math.fmod</A><BR> +<A HREF="manual.html#pdf-math.huge">math.huge</A><BR> +<A HREF="manual.html#pdf-math.log">math.log</A><BR> +<A HREF="manual.html#pdf-math.max">math.max</A><BR> +<A HREF="manual.html#pdf-math.maxinteger">math.maxinteger</A><BR> +<A HREF="manual.html#pdf-math.min">math.min</A><BR> +<A HREF="manual.html#pdf-math.mininteger">math.mininteger</A><BR> +<A HREF="manual.html#pdf-math.modf">math.modf</A><BR> +<A HREF="manual.html#pdf-math.pi">math.pi</A><BR> +<A HREF="manual.html#pdf-math.rad">math.rad</A><BR> +<A HREF="manual.html#pdf-math.random">math.random</A><BR> +<A HREF="manual.html#pdf-math.randomseed">math.randomseed</A><BR> +<A HREF="manual.html#pdf-math.sin">math.sin</A><BR> +<A HREF="manual.html#pdf-math.sqrt">math.sqrt</A><BR> +<A HREF="manual.html#pdf-math.tan">math.tan</A><BR> +<A HREF="manual.html#pdf-math.tointeger">math.tointeger</A><BR> +<A HREF="manual.html#pdf-math.type">math.type</A><BR> +<A HREF="manual.html#pdf-math.ult">math.ult</A><BR> + +<P> +<A HREF="manual.html#6.9">os</A><BR> +<A HREF="manual.html#pdf-os.clock">os.clock</A><BR> +<A HREF="manual.html#pdf-os.date">os.date</A><BR> +<A HREF="manual.html#pdf-os.difftime">os.difftime</A><BR> +<A HREF="manual.html#pdf-os.execute">os.execute</A><BR> +<A HREF="manual.html#pdf-os.exit">os.exit</A><BR> +<A HREF="manual.html#pdf-os.getenv">os.getenv</A><BR> +<A HREF="manual.html#pdf-os.remove">os.remove</A><BR> +<A HREF="manual.html#pdf-os.rename">os.rename</A><BR> +<A HREF="manual.html#pdf-os.setlocale">os.setlocale</A><BR> +<A HREF="manual.html#pdf-os.time">os.time</A><BR> +<A HREF="manual.html#pdf-os.tmpname">os.tmpname</A><BR> + +<P> +<A HREF="manual.html#6.3">package</A><BR> +<A HREF="manual.html#pdf-package.config">package.config</A><BR> +<A HREF="manual.html#pdf-package.cpath">package.cpath</A><BR> +<A HREF="manual.html#pdf-package.loaded">package.loaded</A><BR> +<A HREF="manual.html#pdf-package.loadlib">package.loadlib</A><BR> +<A HREF="manual.html#pdf-package.path">package.path</A><BR> +<A HREF="manual.html#pdf-package.preload">package.preload</A><BR> +<A HREF="manual.html#pdf-package.searchers">package.searchers</A><BR> +<A HREF="manual.html#pdf-package.searchpath">package.searchpath</A><BR> + +<P> +<A HREF="manual.html#6.4">string</A><BR> +<A HREF="manual.html#pdf-string.byte">string.byte</A><BR> +<A HREF="manual.html#pdf-string.char">string.char</A><BR> +<A HREF="manual.html#pdf-string.dump">string.dump</A><BR> +<A HREF="manual.html#pdf-string.find">string.find</A><BR> +<A HREF="manual.html#pdf-string.format">string.format</A><BR> +<A HREF="manual.html#pdf-string.gmatch">string.gmatch</A><BR> +<A HREF="manual.html#pdf-string.gsub">string.gsub</A><BR> +<A HREF="manual.html#pdf-string.len">string.len</A><BR> +<A HREF="manual.html#pdf-string.lower">string.lower</A><BR> +<A HREF="manual.html#pdf-string.match">string.match</A><BR> +<A HREF="manual.html#pdf-string.pack">string.pack</A><BR> +<A HREF="manual.html#pdf-string.packsize">string.packsize</A><BR> +<A HREF="manual.html#pdf-string.rep">string.rep</A><BR> +<A HREF="manual.html#pdf-string.reverse">string.reverse</A><BR> +<A HREF="manual.html#pdf-string.sub">string.sub</A><BR> +<A HREF="manual.html#pdf-string.unpack">string.unpack</A><BR> +<A HREF="manual.html#pdf-string.upper">string.upper</A><BR> + +<P> +<A HREF="manual.html#6.6">table</A><BR> +<A HREF="manual.html#pdf-table.concat">table.concat</A><BR> +<A HREF="manual.html#pdf-table.insert">table.insert</A><BR> +<A HREF="manual.html#pdf-table.move">table.move</A><BR> +<A HREF="manual.html#pdf-table.pack">table.pack</A><BR> +<A HREF="manual.html#pdf-table.remove">table.remove</A><BR> +<A HREF="manual.html#pdf-table.sort">table.sort</A><BR> +<A HREF="manual.html#pdf-table.unpack">table.unpack</A><BR> + +<P> +<A HREF="manual.html#6.5">utf8</A><BR> +<A HREF="manual.html#pdf-utf8.char">utf8.char</A><BR> +<A HREF="manual.html#pdf-utf8.charpattern">utf8.charpattern</A><BR> +<A HREF="manual.html#pdf-utf8.codepoint">utf8.codepoint</A><BR> +<A HREF="manual.html#pdf-utf8.codes">utf8.codes</A><BR> +<A HREF="manual.html#pdf-utf8.len">utf8.len</A><BR> +<A HREF="manual.html#pdf-utf8.offset">utf8.offset</A><BR> + +<H3><A NAME="metamethods">metamethods</A></H3> +<P> +<A HREF="manual.html#2.4">__add</A><BR> +<A HREF="manual.html#2.4">__band</A><BR> +<A HREF="manual.html#2.4">__bnot</A><BR> +<A HREF="manual.html#2.4">__bor</A><BR> +<A HREF="manual.html#2.4">__bxor</A><BR> +<A HREF="manual.html#2.4">__call</A><BR> +<A HREF="manual.html#2.4">__concat</A><BR> +<A HREF="manual.html#2.4">__div</A><BR> +<A HREF="manual.html#2.4">__eq</A><BR> +<A HREF="manual.html#2.5.1">__gc</A><BR> +<A HREF="manual.html#2.4">__idiv</A><BR> +<A HREF="manual.html#2.4">__index</A><BR> +<A HREF="manual.html#2.4">__le</A><BR> +<A HREF="manual.html#2.4">__len</A><BR> +<A HREF="manual.html#2.4">__lt</A><BR> +<A HREF="manual.html#pdf-getmetatable">__metatable</A><BR> +<A HREF="manual.html#2.4">__mod</A><BR> +<A HREF="manual.html#2.5.2">__mode</A><BR> +<A HREF="manual.html#2.4">__mul</A><BR> +<A HREF="manual.html#luaL_newmetatable">__name</A><BR> +<A HREF="manual.html#2.4">__newindex</A><BR> +<A HREF="manual.html#pdf-pairs">__pairs</A><BR> +<A HREF="manual.html#2.4">__pow</A><BR> +<A HREF="manual.html#2.4">__shl</A><BR> +<A HREF="manual.html#2.4">__shr</A><BR> +<A HREF="manual.html#2.4">__sub</A><BR> +<A HREF="manual.html#pdf-tostring">__tostring</A><BR> +<A HREF="manual.html#2.4">__unm</A><BR> + +<H3><A NAME="env">environment<BR>variables</A></H3> +<P> +<A HREF="manual.html#pdf-LUA_CPATH">LUA_CPATH</A><BR> +<A HREF="manual.html#pdf-LUA_CPATH_5_3">LUA_CPATH_5_3</A><BR> +<A HREF="manual.html#pdf-LUA_INIT">LUA_INIT</A><BR> +<A HREF="manual.html#pdf-LUA_INIT_5_3">LUA_INIT_5_3</A><BR> +<A HREF="manual.html#pdf-LUA_PATH">LUA_PATH</A><BR> +<A HREF="manual.html#pdf-LUA_PATH_5_3">LUA_PATH_5_3</A><BR> + +</TD> +<TD> +<H3><A NAME="api">C API</A></H3> +<P> +<A HREF="manual.html#lua_Alloc">lua_Alloc</A><BR> +<A HREF="manual.html#lua_CFunction">lua_CFunction</A><BR> +<A HREF="manual.html#lua_Debug">lua_Debug</A><BR> +<A HREF="manual.html#lua_Hook">lua_Hook</A><BR> +<A HREF="manual.html#lua_Integer">lua_Integer</A><BR> +<A HREF="manual.html#lua_KContext">lua_KContext</A><BR> +<A HREF="manual.html#lua_KFunction">lua_KFunction</A><BR> +<A HREF="manual.html#lua_Number">lua_Number</A><BR> +<A HREF="manual.html#lua_Reader">lua_Reader</A><BR> +<A HREF="manual.html#lua_State">lua_State</A><BR> +<A HREF="manual.html#lua_Unsigned">lua_Unsigned</A><BR> +<A HREF="manual.html#lua_Writer">lua_Writer</A><BR> + +<P> +<A HREF="manual.html#lua_absindex">lua_absindex</A><BR> +<A HREF="manual.html#lua_arith">lua_arith</A><BR> +<A HREF="manual.html#lua_atpanic">lua_atpanic</A><BR> +<A HREF="manual.html#lua_call">lua_call</A><BR> +<A HREF="manual.html#lua_callk">lua_callk</A><BR> +<A HREF="manual.html#lua_checkstack">lua_checkstack</A><BR> +<A HREF="manual.html#lua_close">lua_close</A><BR> +<A HREF="manual.html#lua_compare">lua_compare</A><BR> +<A HREF="manual.html#lua_concat">lua_concat</A><BR> +<A HREF="manual.html#lua_copy">lua_copy</A><BR> +<A HREF="manual.html#lua_createtable">lua_createtable</A><BR> +<A HREF="manual.html#lua_dump">lua_dump</A><BR> +<A HREF="manual.html#lua_error">lua_error</A><BR> +<A HREF="manual.html#lua_gc">lua_gc</A><BR> +<A HREF="manual.html#lua_getallocf">lua_getallocf</A><BR> +<A HREF="manual.html#lua_getextraspace">lua_getextraspace</A><BR> +<A HREF="manual.html#lua_getfield">lua_getfield</A><BR> +<A HREF="manual.html#lua_getglobal">lua_getglobal</A><BR> +<A HREF="manual.html#lua_gethook">lua_gethook</A><BR> +<A HREF="manual.html#lua_gethookcount">lua_gethookcount</A><BR> +<A HREF="manual.html#lua_gethookmask">lua_gethookmask</A><BR> +<A HREF="manual.html#lua_geti">lua_geti</A><BR> +<A HREF="manual.html#lua_getinfo">lua_getinfo</A><BR> +<A HREF="manual.html#lua_getlocal">lua_getlocal</A><BR> +<A HREF="manual.html#lua_getmetatable">lua_getmetatable</A><BR> +<A HREF="manual.html#lua_getstack">lua_getstack</A><BR> +<A HREF="manual.html#lua_gettable">lua_gettable</A><BR> +<A HREF="manual.html#lua_gettop">lua_gettop</A><BR> +<A HREF="manual.html#lua_getupvalue">lua_getupvalue</A><BR> +<A HREF="manual.html#lua_getuservalue">lua_getuservalue</A><BR> +<A HREF="manual.html#lua_insert">lua_insert</A><BR> +<A HREF="manual.html#lua_isboolean">lua_isboolean</A><BR> +<A HREF="manual.html#lua_iscfunction">lua_iscfunction</A><BR> +<A HREF="manual.html#lua_isfunction">lua_isfunction</A><BR> +<A HREF="manual.html#lua_isinteger">lua_isinteger</A><BR> +<A HREF="manual.html#lua_islightuserdata">lua_islightuserdata</A><BR> +<A HREF="manual.html#lua_isnil">lua_isnil</A><BR> +<A HREF="manual.html#lua_isnone">lua_isnone</A><BR> +<A HREF="manual.html#lua_isnoneornil">lua_isnoneornil</A><BR> +<A HREF="manual.html#lua_isnumber">lua_isnumber</A><BR> +<A HREF="manual.html#lua_isstring">lua_isstring</A><BR> +<A HREF="manual.html#lua_istable">lua_istable</A><BR> +<A HREF="manual.html#lua_isthread">lua_isthread</A><BR> +<A HREF="manual.html#lua_isuserdata">lua_isuserdata</A><BR> +<A HREF="manual.html#lua_isyieldable">lua_isyieldable</A><BR> +<A HREF="manual.html#lua_len">lua_len</A><BR> +<A HREF="manual.html#lua_load">lua_load</A><BR> +<A HREF="manual.html#lua_newstate">lua_newstate</A><BR> +<A HREF="manual.html#lua_newtable">lua_newtable</A><BR> +<A HREF="manual.html#lua_newthread">lua_newthread</A><BR> +<A HREF="manual.html#lua_newuserdata">lua_newuserdata</A><BR> +<A HREF="manual.html#lua_next">lua_next</A><BR> +<A HREF="manual.html#lua_numbertointeger">lua_numbertointeger</A><BR> +<A HREF="manual.html#lua_pcall">lua_pcall</A><BR> +<A HREF="manual.html#lua_pcallk">lua_pcallk</A><BR> +<A HREF="manual.html#lua_pop">lua_pop</A><BR> +<A HREF="manual.html#lua_pushboolean">lua_pushboolean</A><BR> +<A HREF="manual.html#lua_pushcclosure">lua_pushcclosure</A><BR> +<A HREF="manual.html#lua_pushcfunction">lua_pushcfunction</A><BR> +<A HREF="manual.html#lua_pushfstring">lua_pushfstring</A><BR> +<A HREF="manual.html#lua_pushglobaltable">lua_pushglobaltable</A><BR> +<A HREF="manual.html#lua_pushinteger">lua_pushinteger</A><BR> +<A HREF="manual.html#lua_pushlightuserdata">lua_pushlightuserdata</A><BR> +<A HREF="manual.html#lua_pushliteral">lua_pushliteral</A><BR> +<A HREF="manual.html#lua_pushlstring">lua_pushlstring</A><BR> +<A HREF="manual.html#lua_pushnil">lua_pushnil</A><BR> +<A HREF="manual.html#lua_pushnumber">lua_pushnumber</A><BR> +<A HREF="manual.html#lua_pushstring">lua_pushstring</A><BR> +<A HREF="manual.html#lua_pushthread">lua_pushthread</A><BR> +<A HREF="manual.html#lua_pushvalue">lua_pushvalue</A><BR> +<A HREF="manual.html#lua_pushvfstring">lua_pushvfstring</A><BR> +<A HREF="manual.html#lua_rawequal">lua_rawequal</A><BR> +<A HREF="manual.html#lua_rawget">lua_rawget</A><BR> +<A HREF="manual.html#lua_rawgeti">lua_rawgeti</A><BR> +<A HREF="manual.html#lua_rawgetp">lua_rawgetp</A><BR> +<A HREF="manual.html#lua_rawlen">lua_rawlen</A><BR> +<A HREF="manual.html#lua_rawset">lua_rawset</A><BR> +<A HREF="manual.html#lua_rawseti">lua_rawseti</A><BR> +<A HREF="manual.html#lua_rawsetp">lua_rawsetp</A><BR> +<A HREF="manual.html#lua_register">lua_register</A><BR> +<A HREF="manual.html#lua_remove">lua_remove</A><BR> +<A HREF="manual.html#lua_replace">lua_replace</A><BR> +<A HREF="manual.html#lua_resume">lua_resume</A><BR> +<A HREF="manual.html#lua_rotate">lua_rotate</A><BR> +<A HREF="manual.html#lua_setallocf">lua_setallocf</A><BR> +<A HREF="manual.html#lua_setfield">lua_setfield</A><BR> +<A HREF="manual.html#lua_setglobal">lua_setglobal</A><BR> +<A HREF="manual.html#lua_sethook">lua_sethook</A><BR> +<A HREF="manual.html#lua_seti">lua_seti</A><BR> +<A HREF="manual.html#lua_setlocal">lua_setlocal</A><BR> +<A HREF="manual.html#lua_setmetatable">lua_setmetatable</A><BR> +<A HREF="manual.html#lua_settable">lua_settable</A><BR> +<A HREF="manual.html#lua_settop">lua_settop</A><BR> +<A HREF="manual.html#lua_setupvalue">lua_setupvalue</A><BR> +<A HREF="manual.html#lua_setuservalue">lua_setuservalue</A><BR> +<A HREF="manual.html#lua_status">lua_status</A><BR> +<A HREF="manual.html#lua_stringtonumber">lua_stringtonumber</A><BR> +<A HREF="manual.html#lua_toboolean">lua_toboolean</A><BR> +<A HREF="manual.html#lua_tocfunction">lua_tocfunction</A><BR> +<A HREF="manual.html#lua_tointeger">lua_tointeger</A><BR> +<A HREF="manual.html#lua_tointegerx">lua_tointegerx</A><BR> +<A HREF="manual.html#lua_tolstring">lua_tolstring</A><BR> +<A HREF="manual.html#lua_tonumber">lua_tonumber</A><BR> +<A HREF="manual.html#lua_tonumberx">lua_tonumberx</A><BR> +<A HREF="manual.html#lua_topointer">lua_topointer</A><BR> +<A HREF="manual.html#lua_tostring">lua_tostring</A><BR> +<A HREF="manual.html#lua_tothread">lua_tothread</A><BR> +<A HREF="manual.html#lua_touserdata">lua_touserdata</A><BR> +<A HREF="manual.html#lua_type">lua_type</A><BR> +<A HREF="manual.html#lua_typename">lua_typename</A><BR> +<A HREF="manual.html#lua_upvalueid">lua_upvalueid</A><BR> +<A HREF="manual.html#lua_upvalueindex">lua_upvalueindex</A><BR> +<A HREF="manual.html#lua_upvaluejoin">lua_upvaluejoin</A><BR> +<A HREF="manual.html#lua_version">lua_version</A><BR> +<A HREF="manual.html#lua_xmove">lua_xmove</A><BR> +<A HREF="manual.html#lua_yield">lua_yield</A><BR> +<A HREF="manual.html#lua_yieldk">lua_yieldk</A><BR> + +</TD> +<TD> +<H3><A NAME="auxlib">auxiliary library</A></H3> +<P> +<A HREF="manual.html#luaL_Buffer">luaL_Buffer</A><BR> +<A HREF="manual.html#luaL_Reg">luaL_Reg</A><BR> +<A HREF="manual.html#luaL_Stream">luaL_Stream</A><BR> + +<P> +<A HREF="manual.html#luaL_addchar">luaL_addchar</A><BR> +<A HREF="manual.html#luaL_addlstring">luaL_addlstring</A><BR> +<A HREF="manual.html#luaL_addsize">luaL_addsize</A><BR> +<A HREF="manual.html#luaL_addstring">luaL_addstring</A><BR> +<A HREF="manual.html#luaL_addvalue">luaL_addvalue</A><BR> +<A HREF="manual.html#luaL_argcheck">luaL_argcheck</A><BR> +<A HREF="manual.html#luaL_argerror">luaL_argerror</A><BR> +<A HREF="manual.html#luaL_buffinit">luaL_buffinit</A><BR> +<A HREF="manual.html#luaL_buffinitsize">luaL_buffinitsize</A><BR> +<A HREF="manual.html#luaL_callmeta">luaL_callmeta</A><BR> +<A HREF="manual.html#luaL_checkany">luaL_checkany</A><BR> +<A HREF="manual.html#luaL_checkinteger">luaL_checkinteger</A><BR> +<A HREF="manual.html#luaL_checklstring">luaL_checklstring</A><BR> +<A HREF="manual.html#luaL_checknumber">luaL_checknumber</A><BR> +<A HREF="manual.html#luaL_checkoption">luaL_checkoption</A><BR> +<A HREF="manual.html#luaL_checkstack">luaL_checkstack</A><BR> +<A HREF="manual.html#luaL_checkstring">luaL_checkstring</A><BR> +<A HREF="manual.html#luaL_checktype">luaL_checktype</A><BR> +<A HREF="manual.html#luaL_checkudata">luaL_checkudata</A><BR> +<A HREF="manual.html#luaL_checkversion">luaL_checkversion</A><BR> +<A HREF="manual.html#luaL_dofile">luaL_dofile</A><BR> +<A HREF="manual.html#luaL_dostring">luaL_dostring</A><BR> +<A HREF="manual.html#luaL_error">luaL_error</A><BR> +<A HREF="manual.html#luaL_execresult">luaL_execresult</A><BR> +<A HREF="manual.html#luaL_fileresult">luaL_fileresult</A><BR> +<A HREF="manual.html#luaL_getmetafield">luaL_getmetafield</A><BR> +<A HREF="manual.html#luaL_getmetatable">luaL_getmetatable</A><BR> +<A HREF="manual.html#luaL_getsubtable">luaL_getsubtable</A><BR> +<A HREF="manual.html#luaL_gsub">luaL_gsub</A><BR> +<A HREF="manual.html#luaL_len">luaL_len</A><BR> +<A HREF="manual.html#luaL_loadbuffer">luaL_loadbuffer</A><BR> +<A HREF="manual.html#luaL_loadbufferx">luaL_loadbufferx</A><BR> +<A HREF="manual.html#luaL_loadfile">luaL_loadfile</A><BR> +<A HREF="manual.html#luaL_loadfilex">luaL_loadfilex</A><BR> +<A HREF="manual.html#luaL_loadstring">luaL_loadstring</A><BR> +<A HREF="manual.html#luaL_newlib">luaL_newlib</A><BR> +<A HREF="manual.html#luaL_newlibtable">luaL_newlibtable</A><BR> +<A HREF="manual.html#luaL_newmetatable">luaL_newmetatable</A><BR> +<A HREF="manual.html#luaL_newstate">luaL_newstate</A><BR> +<A HREF="manual.html#luaL_openlibs">luaL_openlibs</A><BR> +<A HREF="manual.html#luaL_opt">luaL_opt</A><BR> +<A HREF="manual.html#luaL_optinteger">luaL_optinteger</A><BR> +<A HREF="manual.html#luaL_optlstring">luaL_optlstring</A><BR> +<A HREF="manual.html#luaL_optnumber">luaL_optnumber</A><BR> +<A HREF="manual.html#luaL_optstring">luaL_optstring</A><BR> +<A HREF="manual.html#luaL_prepbuffer">luaL_prepbuffer</A><BR> +<A HREF="manual.html#luaL_prepbuffsize">luaL_prepbuffsize</A><BR> +<A HREF="manual.html#luaL_pushresult">luaL_pushresult</A><BR> +<A HREF="manual.html#luaL_pushresultsize">luaL_pushresultsize</A><BR> +<A HREF="manual.html#luaL_ref">luaL_ref</A><BR> +<A HREF="manual.html#luaL_requiref">luaL_requiref</A><BR> +<A HREF="manual.html#luaL_setfuncs">luaL_setfuncs</A><BR> +<A HREF="manual.html#luaL_setmetatable">luaL_setmetatable</A><BR> +<A HREF="manual.html#luaL_testudata">luaL_testudata</A><BR> +<A HREF="manual.html#luaL_tolstring">luaL_tolstring</A><BR> +<A HREF="manual.html#luaL_traceback">luaL_traceback</A><BR> +<A HREF="manual.html#luaL_typename">luaL_typename</A><BR> +<A HREF="manual.html#luaL_unref">luaL_unref</A><BR> +<A HREF="manual.html#luaL_where">luaL_where</A><BR> + +<H3><A NAME="library">standard library</A></H3> +<P> +<A HREF="manual.html#pdf-luaopen_base">luaopen_base</A><BR> +<A HREF="manual.html#pdf-luaopen_coroutine">luaopen_coroutine</A><BR> +<A HREF="manual.html#pdf-luaopen_debug">luaopen_debug</A><BR> +<A HREF="manual.html#pdf-luaopen_io">luaopen_io</A><BR> +<A HREF="manual.html#pdf-luaopen_math">luaopen_math</A><BR> +<A HREF="manual.html#pdf-luaopen_os">luaopen_os</A><BR> +<A HREF="manual.html#pdf-luaopen_package">luaopen_package</A><BR> +<A HREF="manual.html#pdf-luaopen_string">luaopen_string</A><BR> +<A HREF="manual.html#pdf-luaopen_table">luaopen_table</A><BR> +<A HREF="manual.html#pdf-luaopen_utf8">luaopen_utf8</A><BR> + +<H3><A NAME="constants">constants</A></H3> +<P> +<A HREF="manual.html#pdf-LUA_ERRERR">LUA_ERRERR</A><BR> +<A HREF="manual.html#pdf-LUA_ERRFILE">LUA_ERRFILE</A><BR> +<A HREF="manual.html#pdf-LUA_ERRGCMM">LUA_ERRGCMM</A><BR> +<A HREF="manual.html#pdf-LUA_ERRMEM">LUA_ERRMEM</A><BR> +<A HREF="manual.html#pdf-LUA_ERRRUN">LUA_ERRRUN</A><BR> +<A HREF="manual.html#pdf-LUA_ERRSYNTAX">LUA_ERRSYNTAX</A><BR> +<A HREF="manual.html#pdf-LUA_HOOKCALL">LUA_HOOKCALL</A><BR> +<A HREF="manual.html#pdf-LUA_HOOKCOUNT">LUA_HOOKCOUNT</A><BR> +<A HREF="manual.html#pdf-LUA_HOOKLINE">LUA_HOOKLINE</A><BR> +<A HREF="manual.html#pdf-LUA_HOOKRET">LUA_HOOKRET</A><BR> +<A HREF="manual.html#pdf-LUA_HOOKTAILCALL">LUA_HOOKTAILCALL</A><BR> +<A HREF="manual.html#pdf-LUA_MASKCALL">LUA_MASKCALL</A><BR> +<A HREF="manual.html#pdf-LUA_MASKCOUNT">LUA_MASKCOUNT</A><BR> +<A HREF="manual.html#pdf-LUA_MASKLINE">LUA_MASKLINE</A><BR> +<A HREF="manual.html#pdf-LUA_MASKRET">LUA_MASKRET</A><BR> +<A HREF="manual.html#pdf-LUA_MAXINTEGER">LUA_MAXINTEGER</A><BR> +<A HREF="manual.html#pdf-LUA_MININTEGER">LUA_MININTEGER</A><BR> +<A HREF="manual.html#pdf-LUA_MINSTACK">LUA_MINSTACK</A><BR> +<A HREF="manual.html#pdf-LUA_MULTRET">LUA_MULTRET</A><BR> +<A HREF="manual.html#pdf-LUA_NOREF">LUA_NOREF</A><BR> +<A HREF="manual.html#pdf-LUA_OK">LUA_OK</A><BR> +<A HREF="manual.html#pdf-LUA_OPADD">LUA_OPADD</A><BR> +<A HREF="manual.html#pdf-LUA_OPBAND">LUA_OPBAND</A><BR> +<A HREF="manual.html#pdf-LUA_OPBNOT">LUA_OPBNOT</A><BR> +<A HREF="manual.html#pdf-LUA_OPBOR">LUA_OPBOR</A><BR> +<A HREF="manual.html#pdf-LUA_OPBXOR">LUA_OPBXOR</A><BR> +<A HREF="manual.html#pdf-LUA_OPDIV">LUA_OPDIV</A><BR> +<A HREF="manual.html#pdf-LUA_OPEQ">LUA_OPEQ</A><BR> +<A HREF="manual.html#pdf-LUA_OPIDIV">LUA_OPIDIV</A><BR> +<A HREF="manual.html#pdf-LUA_OPLE">LUA_OPLE</A><BR> +<A HREF="manual.html#pdf-LUA_OPLT">LUA_OPLT</A><BR> +<A HREF="manual.html#pdf-LUA_OPMOD">LUA_OPMOD</A><BR> +<A HREF="manual.html#pdf-LUA_OPMUL">LUA_OPMUL</A><BR> +<A HREF="manual.html#pdf-LUA_OPPOW">LUA_OPPOW</A><BR> +<A HREF="manual.html#pdf-LUA_OPSHL">LUA_OPSHL</A><BR> +<A HREF="manual.html#pdf-LUA_OPSHR">LUA_OPSHR</A><BR> +<A HREF="manual.html#pdf-LUA_OPSUB">LUA_OPSUB</A><BR> +<A HREF="manual.html#pdf-LUA_OPUNM">LUA_OPUNM</A><BR> +<A HREF="manual.html#pdf-LUA_REFNIL">LUA_REFNIL</A><BR> +<A HREF="manual.html#pdf-LUA_REGISTRYINDEX">LUA_REGISTRYINDEX</A><BR> +<A HREF="manual.html#pdf-LUA_RIDX_GLOBALS">LUA_RIDX_GLOBALS</A><BR> +<A HREF="manual.html#pdf-LUA_RIDX_MAINTHREAD">LUA_RIDX_MAINTHREAD</A><BR> +<A HREF="manual.html#pdf-LUA_TBOOLEAN">LUA_TBOOLEAN</A><BR> +<A HREF="manual.html#pdf-LUA_TFUNCTION">LUA_TFUNCTION</A><BR> +<A HREF="manual.html#pdf-LUA_TLIGHTUSERDATA">LUA_TLIGHTUSERDATA</A><BR> +<A HREF="manual.html#pdf-LUA_TNIL">LUA_TNIL</A><BR> +<A HREF="manual.html#pdf-LUA_TNONE">LUA_TNONE</A><BR> +<A HREF="manual.html#pdf-LUA_TNUMBER">LUA_TNUMBER</A><BR> +<A HREF="manual.html#pdf-LUA_TSTRING">LUA_TSTRING</A><BR> +<A HREF="manual.html#pdf-LUA_TTABLE">LUA_TTABLE</A><BR> +<A HREF="manual.html#pdf-LUA_TTHREAD">LUA_TTHREAD</A><BR> +<A HREF="manual.html#pdf-LUA_TUSERDATA">LUA_TUSERDATA</A><BR> +<A HREF="manual.html#pdf-LUA_USE_APICHECK">LUA_USE_APICHECK</A><BR> +<A HREF="manual.html#pdf-LUA_YIELD">LUA_YIELD</A><BR> +<A HREF="manual.html#pdf-LUAL_BUFFERSIZE">LUAL_BUFFERSIZE</A><BR> + +</TD> +</TR> +</TABLE> + +<P CLASS="footer"> +Last update: +Tue Aug 25 13:45:14 UTC 2020 +</P> +<!-- +Last change: revised for Lua 5.3.6 +--> + +</BODY> +</HTML> diff --git a/doc/index.css b/doc/index.css new file mode 100644 index 0000000..c961835 --- /dev/null +++ b/doc/index.css @@ -0,0 +1,21 @@ +ul { + list-style-type: none ; +} + +ul.contents { + padding: 0 ; +} + +table { + border: none ; + border-spacing: 0 ; + border-collapse: collapse ; +} + +td { + vertical-align: top ; + padding: 0 ; + text-align: left ; + line-height: 1.25 ; + width: 15% ; +} diff --git a/doc/logo.gif b/doc/logo.gif Binary files differnew file mode 100644 index 0000000..5c77eac --- /dev/null +++ b/doc/logo.gif diff --git a/doc/lua.1 b/doc/lua.1 new file mode 100644 index 0000000..d728d0b --- /dev/null +++ b/doc/lua.1 @@ -0,0 +1,112 @@ +.\" $Id: lua.man,v 1.14 2016/10/17 15:43:50 lhf Exp $ +.TH LUA 1 "$Date: 2016/10/17 15:43:50 $" +.SH NAME +lua \- Lua interpreter +.SH SYNOPSIS +.B lua +[ +.I options +] +[ +.I script +[ +.I args +] +] +.SH DESCRIPTION +.B lua +is the standalone Lua interpreter. +It loads and executes Lua programs, +either in textual source form or +in precompiled binary form. +(Precompiled binaries are output by +.BR luac , +the Lua compiler.) +.B lua +can be used as a batch interpreter and also interactively. +.LP +The given +.I options +are handled in order and then +the Lua program in file +.I script +is loaded and executed. +The given +.I args +are available to +.I script +as strings in a global table named +.BR arg . +If no options or arguments are given, +then +.B "\-v \-i" +is assumed when the standard input is a terminal; +otherwise, +.B "\-" +is assumed. +.LP +In interactive mode, +.B lua +prompts the user, +reads lines from the standard input, +and executes them as they are read. +If the line contains an expression or list of expressions, +then the line is evaluated and the results are printed. +If a line does not contain a complete statement, +then a secondary prompt is displayed and +lines are read until a complete statement is formed or +a syntax error is found. +.LP +At the very start, +before even handling the command line, +.B lua +checks the contents of the environment variables +.B LUA_INIT_5_3 +or +.BR LUA_INIT , +in that order. +If the contents is of the form +.RI '@ filename ', +then +.I filename +is executed. +Otherwise, the string is assumed to be a Lua statement and is executed. +.SH OPTIONS +.TP +.BI \-e " stat" +execute statement +.IR stat . +.TP +.B \-i +enter interactive mode after executing +.IR script . +.TP +.BI \-l " name" +execute the equivalent of +.IB name =require(' name ') +before executing +.IR script . +.TP +.B \-v +show version information. +.TP +.B \-E +ignore environment variables. +.TP +.B \-\- +stop handling options. +.TP +.B \- +stop handling options and execute the standard input as a file. +.SH "SEE ALSO" +.BR luac (1) +.br +The documentation at lua.org, +especially section 7 of the reference manual. +.SH DIAGNOSTICS +Error messages should be self explanatory. +.SH AUTHORS +R. Ierusalimschy, +L. H. de Figueiredo, +W. Celes +.\" EOF diff --git a/doc/lua.css b/doc/lua.css new file mode 100644 index 0000000..cbd0799 --- /dev/null +++ b/doc/lua.css @@ -0,0 +1,161 @@ +html { + background-color: #F8F8F8 ; +} + +body { + background-color: #FFFFFF ; + color: #000000 ; + font-family: Helvetica, Arial, sans-serif ; + text-align: justify ; + line-height: 1.25 ; + margin: 16px auto ; + padding: 32px ; + border: solid #ccc 1px ; + border-radius: 20px ; + max-width: 70em ; + width: 90% ; +} + +h1, h2, h3, h4 { + color: #000080 ; + font-family: Verdana, Geneva, sans-serif ; + font-weight: normal ; + font-style: normal ; + text-align: left ; +} + +h1 { + font-size: 28pt ; +} + +h1 img { + vertical-align: text-bottom ; +} + +h2:before { + content: "\2756" ; + padding-right: 0.5em ; +} + +a { + text-decoration: none ; +} + +a:link { + color: #000080 ; +} + +a:link:hover, a:visited:hover { + background-color: #D0D0FF ; + color: #000080 ; + border-radius: 4px ; +} + +a:link:active, a:visited:active { + color: #FF0000 ; +} + +div.menubar { + padding-bottom: 0.5em ; +} + +p.menubar { + margin-left: 2.5em ; +} + +.menubar a:hover { + margin: -3px -3px -3px -3px ; + padding: 3px 3px 3px 3px ; + border-radius: 4px ; +} + +:target { + background-color: #F0F0F0 ; + margin: -8px ; + padding: 8px ; + border-radius: 8px ; + outline: none ; +} + +hr { + display: none ; +} + +table hr { + background-color: #a0a0a0 ; + color: #a0a0a0 ; + border: 0 ; + height: 1px ; + display: block ; +} + +.footer { + color: gray ; + font-size: x-small ; + text-transform: lowercase ; +} + +input[type=text] { + border: solid #a0a0a0 2px ; + border-radius: 2em ; + background-image: url('images/search.png') ; + background-repeat: no-repeat ; + background-position: 4px center ; + padding-left: 20px ; + height: 2em ; +} + +pre.session { + background-color: #F8F8F8 ; + padding: 1em ; + border-radius: 8px ; +} + +table { + border: none ; + border-spacing: 0 ; + border-collapse: collapse ; +} + +td { + padding: 0 ; + margin: 0 ; +} + +td.gutter { + width: 4% ; +} + +table.columns td { + vertical-align: top ; + padding-bottom: 1em ; + text-align: justify ; + line-height: 1.25 ; +} + +table.book td { + vertical-align: top ; +} + +table.book td.cover { + padding-right: 1em ; +} + +table.book img { + border: solid #000080 1px ; +} + +table.book span { + font-size: small ; + text-align: left ; + display: block ; + margin-top: 0.25em ; +} + +p.logos a:link:hover, p.logos a:visited:hover { + background-color: inherit ; +} + +img { + background-color: white ; +} diff --git a/doc/luac.1 b/doc/luac.1 new file mode 100644 index 0000000..33a4ed0 --- /dev/null +++ b/doc/luac.1 @@ -0,0 +1,118 @@ +.\" $Id: luac.man,v 1.29 2011/11/16 13:53:40 lhf Exp $ +.TH LUAC 1 "$Date: 2011/11/16 13:53:40 $" +.SH NAME +luac \- Lua compiler +.SH SYNOPSIS +.B luac +[ +.I options +] [ +.I filenames +] +.SH DESCRIPTION +.B luac +is the Lua compiler. +It translates programs written in the Lua programming language +into binary files containing precompiled chunks +that can be later loaded and executed. +.LP +The main advantages of precompiling chunks are: +faster loading, +protecting source code from accidental user changes, +and +off-line syntax checking. +Precompiling does not imply faster execution +because in Lua chunks are always compiled into bytecodes before being executed. +.B luac +simply allows those bytecodes to be saved in a file for later execution. +Precompiled chunks are not necessarily smaller than the corresponding source. +The main goal in precompiling is faster loading. +.LP +In the command line, +you can mix +text files containing Lua source and +binary files containing precompiled chunks. +.B luac +produces a single output file containing the combined bytecodes +for all files given. +Executing the combined file is equivalent to executing the given files. +By default, +the output file is named +.BR luac.out , +but you can change this with the +.B \-o +option. +.LP +Precompiled chunks are +.I not +portable across different architectures. +Moreover, +the internal format of precompiled chunks +is likely to change when a new version of Lua is released. +Make sure you save the source files of all Lua programs that you precompile. +.LP +.SH OPTIONS +.TP +.B \-l +produce a listing of the compiled bytecode for Lua's virtual machine. +Listing bytecodes is useful to learn about Lua's virtual machine. +If no files are given, then +.B luac +loads +.B luac.out +and lists its contents. +Use +.B \-l \-l +for a full listing. +.TP +.BI \-o " file" +output to +.IR file , +instead of the default +.BR luac.out . +(You can use +.B "'\-'" +for standard output, +but not on platforms that open standard output in text mode.) +The output file may be one of the given files because +all files are loaded before the output file is written. +Be careful not to overwrite precious files. +.TP +.B \-p +load files but do not generate any output file. +Used mainly for syntax checking and for testing precompiled chunks: +corrupted files will probably generate errors when loaded. +If no files are given, then +.B luac +loads +.B luac.out +and tests its contents. +No messages are displayed if the file loads without errors. +.TP +.B \-s +strip debug information before writing the output file. +This saves some space in very large chunks, +but if errors occur when running a stripped chunk, +then the error messages may not contain the full information they usually do. +In particular, +line numbers and names of local variables are lost. +.TP +.B \-v +show version information. +.TP +.B \-\- +stop handling options. +.TP +.B \- +stop handling options and process standard input. +.SH "SEE ALSO" +.BR lua (1) +.br +The documentation at lua.org. +.SH DIAGNOSTICS +Error messages should be self explanatory. +.SH AUTHORS +R. Ierusalimschy, +L. H. de Figueiredo, +W. Celes +.\" EOF diff --git a/doc/manual.css b/doc/manual.css new file mode 100644 index 0000000..aa0e677 --- /dev/null +++ b/doc/manual.css @@ -0,0 +1,21 @@ +h3 code { + font-family: inherit ; + font-size: inherit ; +} + +pre, code { + font-size: 12pt ; +} + +span.apii { + color: gray ; + float: right ; + font-family: inherit ; + font-style: normal ; + font-size: small ; +} + +h2:before { + content: "" ; + padding-right: 0em ; +} diff --git a/doc/manual.html b/doc/manual.html new file mode 100644 index 0000000..57c7787 --- /dev/null +++ b/doc/manual.html @@ -0,0 +1,10982 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> +<HTML> +<HEAD> +<TITLE>Lua 5.3 Reference Manual</TITLE> +<LINK REL="stylesheet" TYPE="text/css" HREF="lua.css"> +<LINK REL="stylesheet" TYPE="text/css" HREF="manual.css"> +<META HTTP-EQUIV="content-type" CONTENT="text/html; charset=iso-8859-1"> +</HEAD> + +<BODY> + +<H1> +<A HREF="http://www.lua.org/"><IMG SRC="logo.gif" ALT="Lua"></A> +Lua 5.3 Reference Manual +</H1> + +<P> +by Roberto Ierusalimschy, Luiz Henrique de Figueiredo, Waldemar Celes + +<P> +<SMALL> +Copyright © 2015–2020 Lua.org, PUC-Rio. +Freely available under the terms of the +<a href="http://www.lua.org/license.html">Lua license</a>. +</SMALL> + +<DIV CLASS="menubar"> +<A HREF="contents.html#contents">contents</A> +· +<A HREF="contents.html#index">index</A> +· +<A HREF="http://www.lua.org/manual/">other versions</A> +</DIV> + +<!-- ====================================================================== --> +<p> + +<!-- $Id: manual.of,v 1.167.1.2 2018/06/26 15:49:07 roberto Exp $ --> + + + + +<h1>1 – <a name="1">Introduction</a></h1> + +<p> +Lua is a powerful, efficient, lightweight, embeddable scripting language. +It supports procedural programming, +object-oriented programming, functional programming, +data-driven programming, and data description. + + +<p> +Lua combines simple procedural syntax with powerful data description +constructs based on associative arrays and extensible semantics. +Lua is dynamically typed, +runs by interpreting bytecode with a register-based +virtual machine, +and has automatic memory management with +incremental garbage collection, +making it ideal for configuration, scripting, +and rapid prototyping. + + +<p> +Lua is implemented as a library, written in <em>clean C</em>, +the common subset of Standard C and C++. +The Lua distribution includes a host program called <code>lua</code>, +which uses the Lua library to offer a complete, +standalone Lua interpreter, +for interactive or batch use. +Lua is intended to be used both as a powerful, lightweight, +embeddable scripting language for any program that needs one, +and as a powerful but lightweight and efficient stand-alone language. + + +<p> +As an extension language, Lua has no notion of a "main" program: +it works <em>embedded</em> in a host client, +called the <em>embedding program</em> or simply the <em>host</em>. +(Frequently, this host is the stand-alone <code>lua</code> program.) +The host program can invoke functions to execute a piece of Lua code, +can write and read Lua variables, +and can register C functions to be called by Lua code. +Through the use of C functions, Lua can be augmented to cope with +a wide range of different domains, +thus creating customized programming languages sharing a syntactical framework. + + +<p> +Lua is free software, +and is provided as usual with no guarantees, +as stated in its license. +The implementation described in this manual is available +at Lua's official web site, <code>www.lua.org</code>. + + +<p> +Like any other reference manual, +this document is dry in places. +For a discussion of the decisions behind the design of Lua, +see the technical papers available at Lua's web site. +For a detailed introduction to programming in Lua, +see Roberto's book, <em>Programming in Lua</em>. + + + +<h1>2 – <a name="2">Basic Concepts</a></h1> + +<p> +This section describes the basic concepts of the language. + + + +<h2>2.1 – <a name="2.1">Values and Types</a></h2> + +<p> +Lua is a <em>dynamically typed language</em>. +This means that +variables do not have types; only values do. +There are no type definitions in the language. +All values carry their own type. + + +<p> +All values in Lua are <em>first-class values</em>. +This means that all values can be stored in variables, +passed as arguments to other functions, and returned as results. + + +<p> +There are eight basic types in Lua: +<em>nil</em>, <em>boolean</em>, <em>number</em>, +<em>string</em>, <em>function</em>, <em>userdata</em>, +<em>thread</em>, and <em>table</em>. +The type <em>nil</em> has one single value, <b>nil</b>, +whose main property is to be different from any other value; +it usually represents the absence of a useful value. +The type <em>boolean</em> has two values, <b>false</b> and <b>true</b>. +Both <b>nil</b> and <b>false</b> make a condition false; +any other value makes it true. +The type <em>number</em> represents both +integer numbers and real (floating-point) numbers. +The type <em>string</em> represents immutable sequences of bytes. + +Lua is 8-bit clean: +strings can contain any 8-bit value, +including embedded zeros ('<code>\0</code>'). +Lua is also encoding-agnostic; +it makes no assumptions about the contents of a string. + + +<p> +The type <em>number</em> uses two internal representations, +or two subtypes, +one called <em>integer</em> and the other called <em>float</em>. +Lua has explicit rules about when each representation is used, +but it also converts between them automatically as needed (see <a href="#3.4.3">§3.4.3</a>). +Therefore, +the programmer may choose to mostly ignore the difference +between integers and floats +or to assume complete control over the representation of each number. +Standard Lua uses 64-bit integers and double-precision (64-bit) floats, +but you can also compile Lua so that it +uses 32-bit integers and/or single-precision (32-bit) floats. +The option with 32 bits for both integers and floats +is particularly attractive +for small machines and embedded systems. +(See macro <code>LUA_32BITS</code> in file <code>luaconf.h</code>.) + + +<p> +Lua can call (and manipulate) functions written in Lua and +functions written in C (see <a href="#3.4.10">§3.4.10</a>). +Both are represented by the type <em>function</em>. + + +<p> +The type <em>userdata</em> is provided to allow arbitrary C data to +be stored in Lua variables. +A userdata value represents a block of raw memory. +There are two kinds of userdata: +<em>full userdata</em>, +which is an object with a block of memory managed by Lua, +and <em>light userdata</em>, +which is simply a C pointer value. +Userdata has no predefined operations in Lua, +except assignment and identity test. +By using <em>metatables</em>, +the programmer can define operations for full userdata values +(see <a href="#2.4">§2.4</a>). +Userdata values cannot be created or modified in Lua, +only through the C API. +This guarantees the integrity of data owned by the host program. + + +<p> +The type <em>thread</em> represents independent threads of execution +and it is used to implement coroutines (see <a href="#2.6">§2.6</a>). +Lua threads are not related to operating-system threads. +Lua supports coroutines on all systems, +even those that do not support threads natively. + + +<p> +The type <em>table</em> implements associative arrays, +that is, arrays that can have as indices not only numbers, +but any Lua value except <b>nil</b> and NaN. +(<em>Not a Number</em> is a special value used to represent +undefined or unrepresentable numerical results, such as <code>0/0</code>.) +Tables can be <em>heterogeneous</em>; +that is, they can contain values of all types (except <b>nil</b>). +Any key with value <b>nil</b> is not considered part of the table. +Conversely, any key that is not part of a table has +an associated value <b>nil</b>. + + +<p> +Tables are the sole data-structuring mechanism in Lua; +they can be used to represent ordinary arrays, lists, +symbol tables, sets, records, graphs, trees, etc. +To represent records, Lua uses the field name as an index. +The language supports this representation by +providing <code>a.name</code> as syntactic sugar for <code>a["name"]</code>. +There are several convenient ways to create tables in Lua +(see <a href="#3.4.9">§3.4.9</a>). + + +<p> +Like indices, +the values of table fields can be of any type. +In particular, +because functions are first-class values, +table fields can contain functions. +Thus tables can also carry <em>methods</em> (see <a href="#3.4.11">§3.4.11</a>). + + +<p> +The indexing of tables follows +the definition of raw equality in the language. +The expressions <code>a[i]</code> and <code>a[j]</code> +denote the same table element +if and only if <code>i</code> and <code>j</code> are raw equal +(that is, equal without metamethods). +In particular, floats with integral values +are equal to their respective integers +(e.g., <code>1.0 == 1</code>). +To avoid ambiguities, +any float with integral value used as a key +is converted to its respective integer. +For instance, if you write <code>a[2.0] = true</code>, +the actual key inserted into the table will be the +integer <code>2</code>. +(On the other hand, +2 and "<code>2</code>" are different Lua values and therefore +denote different table entries.) + + +<p> +Tables, functions, threads, and (full) userdata values are <em>objects</em>: +variables do not actually <em>contain</em> these values, +only <em>references</em> to them. +Assignment, parameter passing, and function returns +always manipulate references to such values; +these operations do not imply any kind of copy. + + +<p> +The library function <a href="#pdf-type"><code>type</code></a> returns a string describing the type +of a given value (see <a href="#6.1">§6.1</a>). + + + + + +<h2>2.2 – <a name="2.2">Environments and the Global Environment</a></h2> + +<p> +As will be discussed in <a href="#3.2">§3.2</a> and <a href="#3.3.3">§3.3.3</a>, +any reference to a free name +(that is, a name not bound to any declaration) <code>var</code> +is syntactically translated to <code>_ENV.var</code>. +Moreover, every chunk is compiled in the scope of +an external local variable named <code>_ENV</code> (see <a href="#3.3.2">§3.3.2</a>), +so <code>_ENV</code> itself is never a free name in a chunk. + + +<p> +Despite the existence of this external <code>_ENV</code> variable and +the translation of free names, +<code>_ENV</code> is a completely regular name. +In particular, +you can define new variables and parameters with that name. +Each reference to a free name uses the <code>_ENV</code> that is +visible at that point in the program, +following the usual visibility rules of Lua (see <a href="#3.5">§3.5</a>). + + +<p> +Any table used as the value of <code>_ENV</code> is called an <em>environment</em>. + + +<p> +Lua keeps a distinguished environment called the <em>global environment</em>. +This value is kept at a special index in the C registry (see <a href="#4.5">§4.5</a>). +In Lua, the global variable <a href="#pdf-_G"><code>_G</code></a> is initialized with this same value. +(<a href="#pdf-_G"><code>_G</code></a> is never used internally.) + + +<p> +When Lua loads a chunk, +the default value for its <code>_ENV</code> upvalue +is the global environment (see <a href="#pdf-load"><code>load</code></a>). +Therefore, by default, +free names in Lua code refer to entries in the global environment +(and, therefore, they are also called <em>global variables</em>). +Moreover, all standard libraries are loaded in the global environment +and some functions there operate on that environment. +You can use <a href="#pdf-load"><code>load</code></a> (or <a href="#pdf-loadfile"><code>loadfile</code></a>) +to load a chunk with a different environment. +(In C, you have to load the chunk and then change the value +of its first upvalue.) + + + + + +<h2>2.3 – <a name="2.3">Error Handling</a></h2> + +<p> +Because Lua is an embedded extension language, +all Lua actions start from C code in the host program +calling a function from the Lua library. +(When you use Lua standalone, +the <code>lua</code> application is the host program.) +Whenever an error occurs during +the compilation or execution of a Lua chunk, +control returns to the host, +which can take appropriate measures +(such as printing an error message). + + +<p> +Lua code can explicitly generate an error by calling the +<a href="#pdf-error"><code>error</code></a> function. +If you need to catch errors in Lua, +you can use <a href="#pdf-pcall"><code>pcall</code></a> or <a href="#pdf-xpcall"><code>xpcall</code></a> +to call a given function in <em>protected mode</em>. + + +<p> +Whenever there is an error, +an <em>error object</em> (also called an <em>error message</em>) +is propagated with information about the error. +Lua itself only generates errors whose error object is a string, +but programs may generate errors with +any value as the error object. +It is up to the Lua program or its host to handle such error objects. + + +<p> +When you use <a href="#pdf-xpcall"><code>xpcall</code></a> or <a href="#lua_pcall"><code>lua_pcall</code></a>, +you may give a <em>message handler</em> +to be called in case of errors. +This function is called with the original error object +and returns a new error object. +It is called before the error unwinds the stack, +so that it can gather more information about the error, +for instance by inspecting the stack and creating a stack traceback. +This message handler is still protected by the protected call; +so, an error inside the message handler +will call the message handler again. +If this loop goes on for too long, +Lua breaks it and returns an appropriate message. +(The message handler is called only for regular runtime errors. +It is not called for memory-allocation errors +nor for errors while running finalizers.) + + + + + +<h2>2.4 – <a name="2.4">Metatables and Metamethods</a></h2> + +<p> +Every value in Lua can have a <em>metatable</em>. +This <em>metatable</em> is an ordinary Lua table +that defines the behavior of the original value +under certain special operations. +You can change several aspects of the behavior +of operations over a value by setting specific fields in its metatable. +For instance, when a non-numeric value is the operand of an addition, +Lua checks for a function in the field "<code>__add</code>" of the value's metatable. +If it finds one, +Lua calls this function to perform the addition. + + +<p> +The key for each event in a metatable is a string +with the event name prefixed by two underscores; +the corresponding values are called <em>metamethods</em>. +In the previous example, the key is "<code>__add</code>" +and the metamethod is the function that performs the addition. +Unless stated otherwise, +metamethods should be function values. + + +<p> +You can query the metatable of any value +using the <a href="#pdf-getmetatable"><code>getmetatable</code></a> function. +Lua queries metamethods in metatables using a raw access (see <a href="#pdf-rawget"><code>rawget</code></a>). +So, to retrieve the metamethod for event <code>ev</code> in object <code>o</code>, +Lua does the equivalent to the following code: + +<pre> + rawget(getmetatable(<em>o</em>) or {}, "__<em>ev</em>") +</pre> + +<p> +You can replace the metatable of tables +using the <a href="#pdf-setmetatable"><code>setmetatable</code></a> function. +You cannot change the metatable of other types from Lua code +(except by using the debug library (<a href="#6.10">§6.10</a>)); +you should use the C API for that. + + +<p> +Tables and full userdata have individual metatables +(although multiple tables and userdata can share their metatables). +Values of all other types share one single metatable per type; +that is, there is one single metatable for all numbers, +one for all strings, etc. +By default, a value has no metatable, +but the string library sets a metatable for the string type (see <a href="#6.4">§6.4</a>). + + +<p> +A metatable controls how an object behaves in +arithmetic operations, bitwise operations, +order comparisons, concatenation, length operation, calls, and indexing. +A metatable also can define a function to be called +when a userdata or a table is garbage collected (<a href="#2.5">§2.5</a>). + + +<p> +For the unary operators (negation, length, and bitwise NOT), +the metamethod is computed and called with a dummy second operand, +equal to the first one. +This extra operand is only to simplify Lua's internals +(by making these operators behave like a binary operation) +and may be removed in future versions. +(For most uses this extra operand is irrelevant.) + + +<p> +A detailed list of events controlled by metatables is given next. +Each operation is identified by its corresponding key. + + + +<ul> + +<li><b><code>__add</code>: </b> +the addition (<code>+</code>) operation. +If any operand for an addition is not a number +(nor a string coercible to a number), +Lua will try to call a metamethod. +First, Lua will check the first operand (even if it is valid). +If that operand does not define a metamethod for <code>__add</code>, +then Lua will check the second operand. +If Lua can find a metamethod, +it calls the metamethod with the two operands as arguments, +and the result of the call +(adjusted to one value) +is the result of the operation. +Otherwise, +it raises an error. +</li> + +<li><b><code>__sub</code>: </b> +the subtraction (<code>-</code>) operation. +Behavior similar to the addition operation. +</li> + +<li><b><code>__mul</code>: </b> +the multiplication (<code>*</code>) operation. +Behavior similar to the addition operation. +</li> + +<li><b><code>__div</code>: </b> +the division (<code>/</code>) operation. +Behavior similar to the addition operation. +</li> + +<li><b><code>__mod</code>: </b> +the modulo (<code>%</code>) operation. +Behavior similar to the addition operation. +</li> + +<li><b><code>__pow</code>: </b> +the exponentiation (<code>^</code>) operation. +Behavior similar to the addition operation. +</li> + +<li><b><code>__unm</code>: </b> +the negation (unary <code>-</code>) operation. +Behavior similar to the addition operation. +</li> + +<li><b><code>__idiv</code>: </b> +the floor division (<code>//</code>) operation. +Behavior similar to the addition operation. +</li> + +<li><b><code>__band</code>: </b> +the bitwise AND (<code>&</code>) operation. +Behavior similar to the addition operation, +except that Lua will try a metamethod +if any operand is neither an integer +nor a value coercible to an integer (see <a href="#3.4.3">§3.4.3</a>). +</li> + +<li><b><code>__bor</code>: </b> +the bitwise OR (<code>|</code>) operation. +Behavior similar to the bitwise AND operation. +</li> + +<li><b><code>__bxor</code>: </b> +the bitwise exclusive OR (binary <code>~</code>) operation. +Behavior similar to the bitwise AND operation. +</li> + +<li><b><code>__bnot</code>: </b> +the bitwise NOT (unary <code>~</code>) operation. +Behavior similar to the bitwise AND operation. +</li> + +<li><b><code>__shl</code>: </b> +the bitwise left shift (<code><<</code>) operation. +Behavior similar to the bitwise AND operation. +</li> + +<li><b><code>__shr</code>: </b> +the bitwise right shift (<code>>></code>) operation. +Behavior similar to the bitwise AND operation. +</li> + +<li><b><code>__concat</code>: </b> +the concatenation (<code>..</code>) operation. +Behavior similar to the addition operation, +except that Lua will try a metamethod +if any operand is neither a string nor a number +(which is always coercible to a string). +</li> + +<li><b><code>__len</code>: </b> +the length (<code>#</code>) operation. +If the object is not a string, +Lua will try its metamethod. +If there is a metamethod, +Lua calls it with the object as argument, +and the result of the call +(always adjusted to one value) +is the result of the operation. +If there is no metamethod but the object is a table, +then Lua uses the table length operation (see <a href="#3.4.7">§3.4.7</a>). +Otherwise, Lua raises an error. +</li> + +<li><b><code>__eq</code>: </b> +the equal (<code>==</code>) operation. +Behavior similar to the addition operation, +except that Lua will try a metamethod only when the values +being compared are either both tables or both full userdata +and they are not primitively equal. +The result of the call is always converted to a boolean. +</li> + +<li><b><code>__lt</code>: </b> +the less than (<code><</code>) operation. +Behavior similar to the addition operation, +except that Lua will try a metamethod only when the values +being compared are neither both numbers nor both strings. +The result of the call is always converted to a boolean. +</li> + +<li><b><code>__le</code>: </b> +the less equal (<code><=</code>) operation. +Unlike other operations, +the less-equal operation can use two different events. +First, Lua looks for the <code>__le</code> metamethod in both operands, +like in the less than operation. +If it cannot find such a metamethod, +then it will try the <code>__lt</code> metamethod, +assuming that <code>a <= b</code> is equivalent to <code>not (b < a)</code>. +As with the other comparison operators, +the result is always a boolean. +(This use of the <code>__lt</code> event can be removed in future versions; +it is also slower than a real <code>__le</code> metamethod.) +</li> + +<li><b><code>__index</code>: </b> +The indexing access operation <code>table[key]</code>. +This event happens when <code>table</code> is not a table or +when <code>key</code> is not present in <code>table</code>. +The metamethod is looked up in <code>table</code>. + + +<p> +Despite the name, +the metamethod for this event can be either a function or a table. +If it is a function, +it is called with <code>table</code> and <code>key</code> as arguments, +and the result of the call +(adjusted to one value) +is the result of the operation. +If it is a table, +the final result is the result of indexing this table with <code>key</code>. +(This indexing is regular, not raw, +and therefore can trigger another metamethod.) +</li> + +<li><b><code>__newindex</code>: </b> +The indexing assignment <code>table[key] = value</code>. +Like the index event, +this event happens when <code>table</code> is not a table or +when <code>key</code> is not present in <code>table</code>. +The metamethod is looked up in <code>table</code>. + + +<p> +Like with indexing, +the metamethod for this event can be either a function or a table. +If it is a function, +it is called with <code>table</code>, <code>key</code>, and <code>value</code> as arguments. +If it is a table, +Lua does an indexing assignment to this table with the same key and value. +(This assignment is regular, not raw, +and therefore can trigger another metamethod.) + + +<p> +Whenever there is a <code>__newindex</code> metamethod, +Lua does not perform the primitive assignment. +(If necessary, +the metamethod itself can call <a href="#pdf-rawset"><code>rawset</code></a> +to do the assignment.) +</li> + +<li><b><code>__call</code>: </b> +The call operation <code>func(args)</code>. +This event happens when Lua tries to call a non-function value +(that is, <code>func</code> is not a function). +The metamethod is looked up in <code>func</code>. +If present, +the metamethod is called with <code>func</code> as its first argument, +followed by the arguments of the original call (<code>args</code>). +All results of the call +are the result of the operation. +(This is the only metamethod that allows multiple results.) +</li> + +</ul> + +<p> +It is a good practice to add all needed metamethods to a table +before setting it as a metatable of some object. +In particular, the <code>__gc</code> metamethod works only when this order +is followed (see <a href="#2.5.1">§2.5.1</a>). + + +<p> +Because metatables are regular tables, +they can contain arbitrary fields, +not only the event names defined above. +Some functions in the standard library +(e.g., <a href="#pdf-tostring"><code>tostring</code></a>) +use other fields in metatables for their own purposes. + + + + + +<h2>2.5 – <a name="2.5">Garbage Collection</a></h2> + +<p> +Lua performs automatic memory management. +This means that +you do not have to worry about allocating memory for new objects +or freeing it when the objects are no longer needed. +Lua manages memory automatically by running +a <em>garbage collector</em> to collect all <em>dead objects</em> +(that is, objects that are no longer accessible from Lua). +All memory used by Lua is subject to automatic management: +strings, tables, userdata, functions, threads, internal structures, etc. + + +<p> +Lua implements an incremental mark-and-sweep collector. +It uses two numbers to control its garbage-collection cycles: +the <em>garbage-collector pause</em> and +the <em>garbage-collector step multiplier</em>. +Both use percentage points as units +(e.g., a value of 100 means an internal value of 1). + + +<p> +The garbage-collector pause +controls how long the collector waits before starting a new cycle. +Larger values make the collector less aggressive. +Values smaller than 100 mean the collector will not wait to +start a new cycle. +A value of 200 means that the collector waits for the total memory in use +to double before starting a new cycle. + + +<p> +The garbage-collector step multiplier +controls the relative speed of the collector relative to +memory allocation. +Larger values make the collector more aggressive but also increase +the size of each incremental step. +You should not use values smaller than 100, +because they make the collector too slow and +can result in the collector never finishing a cycle. +The default is 200, +which means that the collector runs at "twice" +the speed of memory allocation. + + +<p> +If you set the step multiplier to a very large number +(larger than 10% of the maximum number of +bytes that the program may use), +the collector behaves like a stop-the-world collector. +If you then set the pause to 200, +the collector behaves as in old Lua versions, +doing a complete collection every time Lua doubles its +memory usage. + + +<p> +You can change these numbers by calling <a href="#lua_gc"><code>lua_gc</code></a> in C +or <a href="#pdf-collectgarbage"><code>collectgarbage</code></a> in Lua. +You can also use these functions to control +the collector directly (e.g., stop and restart it). + + + +<h3>2.5.1 – <a name="2.5.1">Garbage-Collection Metamethods</a></h3> + +<p> +You can set garbage-collector metamethods for tables +and, using the C API, +for full userdata (see <a href="#2.4">§2.4</a>). +These metamethods are also called <em>finalizers</em>. +Finalizers allow you to coordinate Lua's garbage collection +with external resource management +(such as closing files, network or database connections, +or freeing your own memory). + + +<p> +For an object (table or userdata) to be finalized when collected, +you must <em>mark</em> it for finalization. + +You mark an object for finalization when you set its metatable +and the metatable has a field indexed by the string "<code>__gc</code>". +Note that if you set a metatable without a <code>__gc</code> field +and later create that field in the metatable, +the object will not be marked for finalization. + + +<p> +When a marked object becomes garbage, +it is not collected immediately by the garbage collector. +Instead, Lua puts it in a list. +After the collection, +Lua goes through that list. +For each object in the list, +it checks the object's <code>__gc</code> metamethod: +If it is a function, +Lua calls it with the object as its single argument; +if the metamethod is not a function, +Lua simply ignores it. + + +<p> +At the end of each garbage-collection cycle, +the finalizers for objects are called in +the reverse order that the objects were marked for finalization, +among those collected in that cycle; +that is, the first finalizer to be called is the one associated +with the object marked last in the program. +The execution of each finalizer may occur at any point during +the execution of the regular code. + + +<p> +Because the object being collected must still be used by the finalizer, +that object (and other objects accessible only through it) +must be <em>resurrected</em> by Lua. +Usually, this resurrection is transient, +and the object memory is freed in the next garbage-collection cycle. +However, if the finalizer stores the object in some global place +(e.g., a global variable), +then the resurrection is permanent. +Moreover, if the finalizer marks a finalizing object for finalization again, +its finalizer will be called again in the next cycle where the +object is unreachable. +In any case, +the object memory is freed only in a GC cycle where +the object is unreachable and not marked for finalization. + + +<p> +When you close a state (see <a href="#lua_close"><code>lua_close</code></a>), +Lua calls the finalizers of all objects marked for finalization, +following the reverse order that they were marked. +If any finalizer marks objects for collection during that phase, +these marks have no effect. + + + + + +<h3>2.5.2 – <a name="2.5.2">Weak Tables</a></h3> + +<p> +A <em>weak table</em> is a table whose elements are +<em>weak references</em>. +A weak reference is ignored by the garbage collector. +In other words, +if the only references to an object are weak references, +then the garbage collector will collect that object. + + +<p> +A weak table can have weak keys, weak values, or both. +A table with weak values allows the collection of its values, +but prevents the collection of its keys. +A table with both weak keys and weak values allows the collection of +both keys and values. +In any case, if either the key or the value is collected, +the whole pair is removed from the table. +The weakness of a table is controlled by the +<code>__mode</code> field of its metatable. +If the <code>__mode</code> field is a string containing the character '<code>k</code>', +the keys in the table are weak. +If <code>__mode</code> contains '<code>v</code>', +the values in the table are weak. + + +<p> +A table with weak keys and strong values +is also called an <em>ephemeron table</em>. +In an ephemeron table, +a value is considered reachable only if its key is reachable. +In particular, +if the only reference to a key comes through its value, +the pair is removed. + + +<p> +Any change in the weakness of a table may take effect only +at the next collect cycle. +In particular, if you change the weakness to a stronger mode, +Lua may still collect some items from that table +before the change takes effect. + + +<p> +Only objects that have an explicit construction +are removed from weak tables. +Values, such as numbers and light C functions, +are not subject to garbage collection, +and therefore are not removed from weak tables +(unless their associated values are collected). +Although strings are subject to garbage collection, +they do not have an explicit construction, +and therefore are not removed from weak tables. + + +<p> +Resurrected objects +(that is, objects being finalized +and objects accessible only through objects being finalized) +have a special behavior in weak tables. +They are removed from weak values before running their finalizers, +but are removed from weak keys only in the next collection +after running their finalizers, when such objects are actually freed. +This behavior allows the finalizer to access properties +associated with the object through weak tables. + + +<p> +If a weak table is among the resurrected objects in a collection cycle, +it may not be properly cleared until the next cycle. + + + + + + + +<h2>2.6 – <a name="2.6">Coroutines</a></h2> + +<p> +Lua supports coroutines, +also called <em>collaborative multithreading</em>. +A coroutine in Lua represents an independent thread of execution. +Unlike threads in multithread systems, however, +a coroutine only suspends its execution by explicitly calling +a yield function. + + +<p> +You create a coroutine by calling <a href="#pdf-coroutine.create"><code>coroutine.create</code></a>. +Its sole argument is a function +that is the main function of the coroutine. +The <code>create</code> function only creates a new coroutine and +returns a handle to it (an object of type <em>thread</em>); +it does not start the coroutine. + + +<p> +You execute a coroutine by calling <a href="#pdf-coroutine.resume"><code>coroutine.resume</code></a>. +When you first call <a href="#pdf-coroutine.resume"><code>coroutine.resume</code></a>, +passing as its first argument +a thread returned by <a href="#pdf-coroutine.create"><code>coroutine.create</code></a>, +the coroutine starts its execution by +calling its main function. +Extra arguments passed to <a href="#pdf-coroutine.resume"><code>coroutine.resume</code></a> are passed +as arguments to that function. +After the coroutine starts running, +it runs until it terminates or <em>yields</em>. + + +<p> +A coroutine can terminate its execution in two ways: +normally, when its main function returns +(explicitly or implicitly, after the last instruction); +and abnormally, if there is an unprotected error. +In case of normal termination, +<a href="#pdf-coroutine.resume"><code>coroutine.resume</code></a> returns <b>true</b>, +plus any values returned by the coroutine main function. +In case of errors, <a href="#pdf-coroutine.resume"><code>coroutine.resume</code></a> returns <b>false</b> +plus an error object. + + +<p> +A coroutine yields by calling <a href="#pdf-coroutine.yield"><code>coroutine.yield</code></a>. +When a coroutine yields, +the corresponding <a href="#pdf-coroutine.resume"><code>coroutine.resume</code></a> returns immediately, +even if the yield happens inside nested function calls +(that is, not in the main function, +but in a function directly or indirectly called by the main function). +In the case of a yield, <a href="#pdf-coroutine.resume"><code>coroutine.resume</code></a> also returns <b>true</b>, +plus any values passed to <a href="#pdf-coroutine.yield"><code>coroutine.yield</code></a>. +The next time you resume the same coroutine, +it continues its execution from the point where it yielded, +with the call to <a href="#pdf-coroutine.yield"><code>coroutine.yield</code></a> returning any extra +arguments passed to <a href="#pdf-coroutine.resume"><code>coroutine.resume</code></a>. + + +<p> +Like <a href="#pdf-coroutine.create"><code>coroutine.create</code></a>, +the <a href="#pdf-coroutine.wrap"><code>coroutine.wrap</code></a> function also creates a coroutine, +but instead of returning the coroutine itself, +it returns a function that, when called, resumes the coroutine. +Any arguments passed to this function +go as extra arguments to <a href="#pdf-coroutine.resume"><code>coroutine.resume</code></a>. +<a href="#pdf-coroutine.wrap"><code>coroutine.wrap</code></a> returns all the values returned by <a href="#pdf-coroutine.resume"><code>coroutine.resume</code></a>, +except the first one (the boolean error code). +Unlike <a href="#pdf-coroutine.resume"><code>coroutine.resume</code></a>, +<a href="#pdf-coroutine.wrap"><code>coroutine.wrap</code></a> does not catch errors; +any error is propagated to the caller. + + +<p> +As an example of how coroutines work, +consider the following code: + +<pre> + function foo (a) + print("foo", a) + return coroutine.yield(2*a) + end + + co = coroutine.create(function (a,b) + print("co-body", a, b) + local r = foo(a+1) + print("co-body", r) + local r, s = coroutine.yield(a+b, a-b) + print("co-body", r, s) + return b, "end" + end) + + print("main", coroutine.resume(co, 1, 10)) + print("main", coroutine.resume(co, "r")) + print("main", coroutine.resume(co, "x", "y")) + print("main", coroutine.resume(co, "x", "y")) +</pre><p> +When you run it, it produces the following output: + +<pre> + co-body 1 10 + foo 2 + main true 4 + co-body r + main true 11 -9 + co-body x y + main true 10 end + main false cannot resume dead coroutine +</pre> + +<p> +You can also create and manipulate coroutines through the C API: +see functions <a href="#lua_newthread"><code>lua_newthread</code></a>, <a href="#lua_resume"><code>lua_resume</code></a>, +and <a href="#lua_yield"><code>lua_yield</code></a>. + + + + + +<h1>3 – <a name="3">The Language</a></h1> + +<p> +This section describes the lexis, the syntax, and the semantics of Lua. +In other words, +this section describes +which tokens are valid, +how they can be combined, +and what their combinations mean. + + +<p> +Language constructs will be explained using the usual extended BNF notation, +in which +{<em>a</em>} means 0 or more <em>a</em>'s, and +[<em>a</em>] means an optional <em>a</em>. +Non-terminals are shown like non-terminal, +keywords are shown like <b>kword</b>, +and other terminal symbols are shown like ‘<b>=</b>’. +The complete syntax of Lua can be found in <a href="#9">§9</a> +at the end of this manual. + + + +<h2>3.1 – <a name="3.1">Lexical Conventions</a></h2> + +<p> +Lua is a free-form language. +It ignores spaces (including new lines) and comments +between lexical elements (tokens), +except as delimiters between names and keywords. + + +<p> +<em>Names</em> +(also called <em>identifiers</em>) +in Lua can be any string of letters, +digits, and underscores, +not beginning with a digit and +not being a reserved word. +Identifiers are used to name variables, table fields, and labels. + + +<p> +The following <em>keywords</em> are reserved +and cannot be used as names: + + +<pre> + and break do else elseif end + false for function goto if in + local nil not or repeat return + then true until while +</pre> + +<p> +Lua is a case-sensitive language: +<code>and</code> is a reserved word, but <code>And</code> and <code>AND</code> +are two different, valid names. +As a convention, +programs should avoid creating +names that start with an underscore followed by +one or more uppercase letters (such as <a href="#pdf-_VERSION"><code>_VERSION</code></a>). + + +<p> +The following strings denote other tokens: + +<pre> + + - * / % ^ # + & ~ | << >> // + == ~= <= >= < > = + ( ) { } [ ] :: + ; : , . .. ... +</pre> + +<p> +A <em>short literal string</em> +can be delimited by matching single or double quotes, +and can contain the following C-like escape sequences: +'<code>\a</code>' (bell), +'<code>\b</code>' (backspace), +'<code>\f</code>' (form feed), +'<code>\n</code>' (newline), +'<code>\r</code>' (carriage return), +'<code>\t</code>' (horizontal tab), +'<code>\v</code>' (vertical tab), +'<code>\\</code>' (backslash), +'<code>\"</code>' (quotation mark [double quote]), +and '<code>\'</code>' (apostrophe [single quote]). +A backslash followed by a line break +results in a newline in the string. +The escape sequence '<code>\z</code>' skips the following span +of white-space characters, +including line breaks; +it is particularly useful to break and indent a long literal string +into multiple lines without adding the newlines and spaces +into the string contents. +A short literal string cannot contain unescaped line breaks +nor escapes not forming a valid escape sequence. + + +<p> +We can specify any byte in a short literal string by its numeric value +(including embedded zeros). +This can be done +with the escape sequence <code>\x<em>XX</em></code>, +where <em>XX</em> is a sequence of exactly two hexadecimal digits, +or with the escape sequence <code>\<em>ddd</em></code>, +where <em>ddd</em> is a sequence of up to three decimal digits. +(Note that if a decimal escape sequence is to be followed by a digit, +it must be expressed using exactly three digits.) + + +<p> +The UTF-8 encoding of a Unicode character +can be inserted in a literal string with +the escape sequence <code>\u{<em>XXX</em>}</code> +(note the mandatory enclosing brackets), +where <em>XXX</em> is a sequence of one or more hexadecimal digits +representing the character code point. + + +<p> +Literal strings can also be defined using a long format +enclosed by <em>long brackets</em>. +We define an <em>opening long bracket of level <em>n</em></em> as an opening +square bracket followed by <em>n</em> equal signs followed by another +opening square bracket. +So, an opening long bracket of level 0 is written as <code>[[</code>, +an opening long bracket of level 1 is written as <code>[=[</code>, +and so on. +A <em>closing long bracket</em> is defined similarly; +for instance, +a closing long bracket of level 4 is written as <code>]====]</code>. +A <em>long literal</em> starts with an opening long bracket of any level and +ends at the first closing long bracket of the same level. +It can contain any text except a closing bracket of the same level. +Literals in this bracketed form can run for several lines, +do not interpret any escape sequences, +and ignore long brackets of any other level. +Any kind of end-of-line sequence +(carriage return, newline, carriage return followed by newline, +or newline followed by carriage return) +is converted to a simple newline. + + +<p> +For convenience, +when the opening long bracket is immediately followed by a newline, +the newline is not included in the string. +As an example, in a system using ASCII +(in which '<code>a</code>' is coded as 97, +newline is coded as 10, and '<code>1</code>' is coded as 49), +the five literal strings below denote the same string: + +<pre> + a = 'alo\n123"' + a = "alo\n123\"" + a = '\97lo\10\04923"' + a = [[alo + 123"]] + a = [==[ + alo + 123"]==] +</pre> + +<p> +Any byte in a literal string not +explicitly affected by the previous rules represents itself. +However, Lua opens files for parsing in text mode, +and the system file functions may have problems with +some control characters. +So, it is safer to represent +non-text data as a quoted literal with +explicit escape sequences for the non-text characters. + + +<p> +A <em>numeric constant</em> (or <em>numeral</em>) +can be written with an optional fractional part +and an optional decimal exponent, +marked by a letter '<code>e</code>' or '<code>E</code>'. +Lua also accepts hexadecimal constants, +which start with <code>0x</code> or <code>0X</code>. +Hexadecimal constants also accept an optional fractional part +plus an optional binary exponent, +marked by a letter '<code>p</code>' or '<code>P</code>'. +A numeric constant with a radix point or an exponent +denotes a float; +otherwise, +if its value fits in an integer, +it denotes an integer. +Examples of valid integer constants are + +<pre> + 3 345 0xff 0xBEBADA +</pre><p> +Examples of valid float constants are + +<pre> + 3.0 3.1416 314.16e-2 0.31416E1 34e1 + 0x0.1E 0xA23p-4 0X1.921FB54442D18P+1 +</pre> + +<p> +A <em>comment</em> starts with a double hyphen (<code>--</code>) +anywhere outside a string. +If the text immediately after <code>--</code> is not an opening long bracket, +the comment is a <em>short comment</em>, +which runs until the end of the line. +Otherwise, it is a <em>long comment</em>, +which runs until the corresponding closing long bracket. +Long comments are frequently used to disable code temporarily. + + + + + +<h2>3.2 – <a name="3.2">Variables</a></h2> + +<p> +Variables are places that store values. +There are three kinds of variables in Lua: +global variables, local variables, and table fields. + + +<p> +A single name can denote a global variable or a local variable +(or a function's formal parameter, +which is a particular kind of local variable): + +<pre> + var ::= Name +</pre><p> +Name denotes identifiers, as defined in <a href="#3.1">§3.1</a>. + + +<p> +Any variable name is assumed to be global unless explicitly declared +as a local (see <a href="#3.3.7">§3.3.7</a>). +Local variables are <em>lexically scoped</em>: +local variables can be freely accessed by functions +defined inside their scope (see <a href="#3.5">§3.5</a>). + + +<p> +Before the first assignment to a variable, its value is <b>nil</b>. + + +<p> +Square brackets are used to index a table: + +<pre> + var ::= prefixexp ‘<b>[</b>’ exp ‘<b>]</b>’ +</pre><p> +The meaning of accesses to table fields can be changed via metatables +(see <a href="#2.4">§2.4</a>). + + +<p> +The syntax <code>var.Name</code> is just syntactic sugar for +<code>var["Name"]</code>: + +<pre> + var ::= prefixexp ‘<b>.</b>’ Name +</pre> + +<p> +An access to a global variable <code>x</code> +is equivalent to <code>_ENV.x</code>. +Due to the way that chunks are compiled, +<code>_ENV</code> is never a global name (see <a href="#2.2">§2.2</a>). + + + + + +<h2>3.3 – <a name="3.3">Statements</a></h2> + +<p> +Lua supports an almost conventional set of statements, +similar to those in Pascal or C. +This set includes +assignments, control structures, function calls, +and variable declarations. + + + +<h3>3.3.1 – <a name="3.3.1">Blocks</a></h3> + +<p> +A block is a list of statements, +which are executed sequentially: + +<pre> + block ::= {stat} +</pre><p> +Lua has <em>empty statements</em> +that allow you to separate statements with semicolons, +start a block with a semicolon +or write two semicolons in sequence: + +<pre> + stat ::= ‘<b>;</b>’ +</pre> + +<p> +Function calls and assignments +can start with an open parenthesis. +This possibility leads to an ambiguity in Lua's grammar. +Consider the following fragment: + +<pre> + a = b + c + (print or io.write)('done') +</pre><p> +The grammar could see it in two ways: + +<pre> + a = b + c(print or io.write)('done') + + a = b + c; (print or io.write)('done') +</pre><p> +The current parser always sees such constructions +in the first way, +interpreting the open parenthesis +as the start of the arguments to a call. +To avoid this ambiguity, +it is a good practice to always precede with a semicolon +statements that start with a parenthesis: + +<pre> + ;(print or io.write)('done') +</pre> + +<p> +A block can be explicitly delimited to produce a single statement: + +<pre> + stat ::= <b>do</b> block <b>end</b> +</pre><p> +Explicit blocks are useful +to control the scope of variable declarations. +Explicit blocks are also sometimes used to +add a <b>return</b> statement in the middle +of another block (see <a href="#3.3.4">§3.3.4</a>). + + + + + +<h3>3.3.2 – <a name="3.3.2">Chunks</a></h3> + +<p> +The unit of compilation of Lua is called a <em>chunk</em>. +Syntactically, +a chunk is simply a block: + +<pre> + chunk ::= block +</pre> + +<p> +Lua handles a chunk as the body of an anonymous function +with a variable number of arguments +(see <a href="#3.4.11">§3.4.11</a>). +As such, chunks can define local variables, +receive arguments, and return values. +Moreover, such anonymous function is compiled as in the +scope of an external local variable called <code>_ENV</code> (see <a href="#2.2">§2.2</a>). +The resulting function always has <code>_ENV</code> as its only upvalue, +even if it does not use that variable. + + +<p> +A chunk can be stored in a file or in a string inside the host program. +To execute a chunk, +Lua first <em>loads</em> it, +precompiling the chunk's code into instructions for a virtual machine, +and then Lua executes the compiled code +with an interpreter for the virtual machine. + + +<p> +Chunks can also be precompiled into binary form; +see program <code>luac</code> and function <a href="#pdf-string.dump"><code>string.dump</code></a> for details. +Programs in source and compiled forms are interchangeable; +Lua automatically detects the file type and acts accordingly (see <a href="#pdf-load"><code>load</code></a>). + + + + + +<h3>3.3.3 – <a name="3.3.3">Assignment</a></h3> + +<p> +Lua allows multiple assignments. +Therefore, the syntax for assignment +defines a list of variables on the left side +and a list of expressions on the right side. +The elements in both lists are separated by commas: + +<pre> + stat ::= varlist ‘<b>=</b>’ explist + varlist ::= var {‘<b>,</b>’ var} + explist ::= exp {‘<b>,</b>’ exp} +</pre><p> +Expressions are discussed in <a href="#3.4">§3.4</a>. + + +<p> +Before the assignment, +the list of values is <em>adjusted</em> to the length of +the list of variables. +If there are more values than needed, +the excess values are thrown away. +If there are fewer values than needed, +the list is extended with as many <b>nil</b>'s as needed. +If the list of expressions ends with a function call, +then all values returned by that call enter the list of values, +before the adjustment +(except when the call is enclosed in parentheses; see <a href="#3.4">§3.4</a>). + + +<p> +The assignment statement first evaluates all its expressions +and only then the assignments are performed. +Thus the code + +<pre> + i = 3 + i, a[i] = i+1, 20 +</pre><p> +sets <code>a[3]</code> to 20, without affecting <code>a[4]</code> +because the <code>i</code> in <code>a[i]</code> is evaluated (to 3) +before it is assigned 4. +Similarly, the line + +<pre> + x, y = y, x +</pre><p> +exchanges the values of <code>x</code> and <code>y</code>, +and + +<pre> + x, y, z = y, z, x +</pre><p> +cyclically permutes the values of <code>x</code>, <code>y</code>, and <code>z</code>. + + +<p> +An assignment to a global name <code>x = val</code> +is equivalent to the assignment +<code>_ENV.x = val</code> (see <a href="#2.2">§2.2</a>). + + +<p> +The meaning of assignments to table fields and +global variables (which are actually table fields, too) +can be changed via metatables (see <a href="#2.4">§2.4</a>). + + + + + +<h3>3.3.4 – <a name="3.3.4">Control Structures</a></h3><p> +The control structures +<b>if</b>, <b>while</b>, and <b>repeat</b> have the usual meaning and +familiar syntax: + + + + +<pre> + stat ::= <b>while</b> exp <b>do</b> block <b>end</b> + stat ::= <b>repeat</b> block <b>until</b> exp + stat ::= <b>if</b> exp <b>then</b> block {<b>elseif</b> exp <b>then</b> block} [<b>else</b> block] <b>end</b> +</pre><p> +Lua also has a <b>for</b> statement, in two flavors (see <a href="#3.3.5">§3.3.5</a>). + + +<p> +The condition expression of a +control structure can return any value. +Both <b>false</b> and <b>nil</b> are considered false. +All values different from <b>nil</b> and <b>false</b> are considered true +(in particular, the number 0 and the empty string are also true). + + +<p> +In the <b>repeat</b>–<b>until</b> loop, +the inner block does not end at the <b>until</b> keyword, +but only after the condition. +So, the condition can refer to local variables +declared inside the loop block. + + +<p> +The <b>goto</b> statement transfers the program control to a label. +For syntactical reasons, +labels in Lua are considered statements too: + + + +<pre> + stat ::= <b>goto</b> Name + stat ::= label + label ::= ‘<b>::</b>’ Name ‘<b>::</b>’ +</pre> + +<p> +A label is visible in the entire block where it is defined, +except +inside nested blocks where a label with the same name is defined and +inside nested functions. +A goto may jump to any visible label as long as it does not +enter into the scope of a local variable. + + +<p> +Labels and empty statements are called <em>void statements</em>, +as they perform no actions. + + +<p> +The <b>break</b> statement terminates the execution of a +<b>while</b>, <b>repeat</b>, or <b>for</b> loop, +skipping to the next statement after the loop: + + +<pre> + stat ::= <b>break</b> +</pre><p> +A <b>break</b> ends the innermost enclosing loop. + + +<p> +The <b>return</b> statement is used to return values +from a function or a chunk +(which is an anonymous function). + +Functions can return more than one value, +so the syntax for the <b>return</b> statement is + +<pre> + stat ::= <b>return</b> [explist] [‘<b>;</b>’] +</pre> + +<p> +The <b>return</b> statement can only be written +as the last statement of a block. +If it is really necessary to <b>return</b> in the middle of a block, +then an explicit inner block can be used, +as in the idiom <code>do return end</code>, +because now <b>return</b> is the last statement in its (inner) block. + + + + + +<h3>3.3.5 – <a name="3.3.5">For Statement</a></h3> + +<p> + +The <b>for</b> statement has two forms: +one numerical and one generic. + + +<p> +The numerical <b>for</b> loop repeats a block of code while a +control variable runs through an arithmetic progression. +It has the following syntax: + +<pre> + stat ::= <b>for</b> Name ‘<b>=</b>’ exp ‘<b>,</b>’ exp [‘<b>,</b>’ exp] <b>do</b> block <b>end</b> +</pre><p> +The <em>block</em> is repeated for <em>name</em> starting at the value of +the first <em>exp</em>, until it passes the second <em>exp</em> by steps of the +third <em>exp</em>. +More precisely, a <b>for</b> statement like + +<pre> + for v = <em>e1</em>, <em>e2</em>, <em>e3</em> do <em>block</em> end +</pre><p> +is equivalent to the code: + +<pre> + do + local <em>var</em>, <em>limit</em>, <em>step</em> = tonumber(<em>e1</em>), tonumber(<em>e2</em>), tonumber(<em>e3</em>) + if not (<em>var</em> and <em>limit</em> and <em>step</em>) then error() end + <em>var</em> = <em>var</em> - <em>step</em> + while true do + <em>var</em> = <em>var</em> + <em>step</em> + if (<em>step</em> >= 0 and <em>var</em> > <em>limit</em>) or (<em>step</em> < 0 and <em>var</em> < <em>limit</em>) then + break + end + local v = <em>var</em> + <em>block</em> + end + end +</pre> + +<p> +Note the following: + +<ul> + +<li> +All three control expressions are evaluated only once, +before the loop starts. +They must all result in numbers. +</li> + +<li> +<code><em>var</em></code>, <code><em>limit</em></code>, and <code><em>step</em></code> are invisible variables. +The names shown here are for explanatory purposes only. +</li> + +<li> +If the third expression (the step) is absent, +then a step of 1 is used. +</li> + +<li> +You can use <b>break</b> and <b>goto</b> to exit a <b>for</b> loop. +</li> + +<li> +The loop variable <code>v</code> is local to the loop body. +If you need its value after the loop, +assign it to another variable before exiting the loop. +</li> + +</ul> + +<p> +The generic <b>for</b> statement works over functions, +called <em>iterators</em>. +On each iteration, the iterator function is called to produce a new value, +stopping when this new value is <b>nil</b>. +The generic <b>for</b> loop has the following syntax: + +<pre> + stat ::= <b>for</b> namelist <b>in</b> explist <b>do</b> block <b>end</b> + namelist ::= Name {‘<b>,</b>’ Name} +</pre><p> +A <b>for</b> statement like + +<pre> + for <em>var_1</em>, ···, <em>var_n</em> in <em>explist</em> do <em>block</em> end +</pre><p> +is equivalent to the code: + +<pre> + do + local <em>f</em>, <em>s</em>, <em>var</em> = <em>explist</em> + while true do + local <em>var_1</em>, ···, <em>var_n</em> = <em>f</em>(<em>s</em>, <em>var</em>) + if <em>var_1</em> == nil then break end + <em>var</em> = <em>var_1</em> + <em>block</em> + end + end +</pre><p> +Note the following: + +<ul> + +<li> +<code><em>explist</em></code> is evaluated only once. +Its results are an <em>iterator</em> function, +a <em>state</em>, +and an initial value for the first <em>iterator variable</em>. +</li> + +<li> +<code><em>f</em></code>, <code><em>s</em></code>, and <code><em>var</em></code> are invisible variables. +The names are here for explanatory purposes only. +</li> + +<li> +You can use <b>break</b> to exit a <b>for</b> loop. +</li> + +<li> +The loop variables <code><em>var_i</em></code> are local to the loop; +you cannot use their values after the <b>for</b> ends. +If you need these values, +then assign them to other variables before breaking or exiting the loop. +</li> + +</ul> + + + + +<h3>3.3.6 – <a name="3.3.6">Function Calls as Statements</a></h3><p> +To allow possible side-effects, +function calls can be executed as statements: + +<pre> + stat ::= functioncall +</pre><p> +In this case, all returned values are thrown away. +Function calls are explained in <a href="#3.4.10">§3.4.10</a>. + + + + + +<h3>3.3.7 – <a name="3.3.7">Local Declarations</a></h3><p> +Local variables can be declared anywhere inside a block. +The declaration can include an initial assignment: + +<pre> + stat ::= <b>local</b> namelist [‘<b>=</b>’ explist] +</pre><p> +If present, an initial assignment has the same semantics +of a multiple assignment (see <a href="#3.3.3">§3.3.3</a>). +Otherwise, all variables are initialized with <b>nil</b>. + + +<p> +A chunk is also a block (see <a href="#3.3.2">§3.3.2</a>), +and so local variables can be declared in a chunk outside any explicit block. + + +<p> +The visibility rules for local variables are explained in <a href="#3.5">§3.5</a>. + + + + + + + +<h2>3.4 – <a name="3.4">Expressions</a></h2> + +<p> +The basic expressions in Lua are the following: + +<pre> + exp ::= prefixexp + exp ::= <b>nil</b> | <b>false</b> | <b>true</b> + exp ::= Numeral + exp ::= LiteralString + exp ::= functiondef + exp ::= tableconstructor + exp ::= ‘<b>...</b>’ + exp ::= exp binop exp + exp ::= unop exp + prefixexp ::= var | functioncall | ‘<b>(</b>’ exp ‘<b>)</b>’ +</pre> + +<p> +Numerals and literal strings are explained in <a href="#3.1">§3.1</a>; +variables are explained in <a href="#3.2">§3.2</a>; +function definitions are explained in <a href="#3.4.11">§3.4.11</a>; +function calls are explained in <a href="#3.4.10">§3.4.10</a>; +table constructors are explained in <a href="#3.4.9">§3.4.9</a>. +Vararg expressions, +denoted by three dots ('<code>...</code>'), can only be used when +directly inside a vararg function; +they are explained in <a href="#3.4.11">§3.4.11</a>. + + +<p> +Binary operators comprise arithmetic operators (see <a href="#3.4.1">§3.4.1</a>), +bitwise operators (see <a href="#3.4.2">§3.4.2</a>), +relational operators (see <a href="#3.4.4">§3.4.4</a>), logical operators (see <a href="#3.4.5">§3.4.5</a>), +and the concatenation operator (see <a href="#3.4.6">§3.4.6</a>). +Unary operators comprise the unary minus (see <a href="#3.4.1">§3.4.1</a>), +the unary bitwise NOT (see <a href="#3.4.2">§3.4.2</a>), +the unary logical <b>not</b> (see <a href="#3.4.5">§3.4.5</a>), +and the unary <em>length operator</em> (see <a href="#3.4.7">§3.4.7</a>). + + +<p> +Both function calls and vararg expressions can result in multiple values. +If a function call is used as a statement (see <a href="#3.3.6">§3.3.6</a>), +then its return list is adjusted to zero elements, +thus discarding all returned values. +If an expression is used as the last (or the only) element +of a list of expressions, +then no adjustment is made +(unless the expression is enclosed in parentheses). +In all other contexts, +Lua adjusts the result list to one element, +either discarding all values except the first one +or adding a single <b>nil</b> if there are no values. + + +<p> +Here are some examples: + +<pre> + f() -- adjusted to 0 results + g(f(), x) -- f() is adjusted to 1 result + g(x, f()) -- g gets x plus all results from f() + a,b,c = f(), x -- f() is adjusted to 1 result (c gets nil) + a,b = ... -- a gets the first vararg argument, b gets + -- the second (both a and b can get nil if there + -- is no corresponding vararg argument) + + a,b,c = x, f() -- f() is adjusted to 2 results + a,b,c = f() -- f() is adjusted to 3 results + return f() -- returns all results from f() + return ... -- returns all received vararg arguments + return x,y,f() -- returns x, y, and all results from f() + {f()} -- creates a list with all results from f() + {...} -- creates a list with all vararg arguments + {f(), nil} -- f() is adjusted to 1 result +</pre> + +<p> +Any expression enclosed in parentheses always results in only one value. +Thus, +<code>(f(x,y,z))</code> is always a single value, +even if <code>f</code> returns several values. +(The value of <code>(f(x,y,z))</code> is the first value returned by <code>f</code> +or <b>nil</b> if <code>f</code> does not return any values.) + + + +<h3>3.4.1 – <a name="3.4.1">Arithmetic Operators</a></h3><p> +Lua supports the following arithmetic operators: + +<ul> +<li><b><code>+</code>: </b>addition</li> +<li><b><code>-</code>: </b>subtraction</li> +<li><b><code>*</code>: </b>multiplication</li> +<li><b><code>/</code>: </b>float division</li> +<li><b><code>//</code>: </b>floor division</li> +<li><b><code>%</code>: </b>modulo</li> +<li><b><code>^</code>: </b>exponentiation</li> +<li><b><code>-</code>: </b>unary minus</li> +</ul> + +<p> +With the exception of exponentiation and float division, +the arithmetic operators work as follows: +If both operands are integers, +the operation is performed over integers and the result is an integer. +Otherwise, if both operands are numbers +or strings that can be converted to +numbers (see <a href="#3.4.3">§3.4.3</a>), +then they are converted to floats, +the operation is performed following the usual rules +for floating-point arithmetic +(usually the IEEE 754 standard), +and the result is a float. + + +<p> +Exponentiation and float division (<code>/</code>) +always convert their operands to floats +and the result is always a float. +Exponentiation uses the ISO C function <code>pow</code>, +so that it works for non-integer exponents too. + + +<p> +Floor division (<code>//</code>) is a division +that rounds the quotient towards minus infinity, +that is, the floor of the division of its operands. + + +<p> +Modulo is defined as the remainder of a division +that rounds the quotient towards minus infinity (floor division). + + +<p> +In case of overflows in integer arithmetic, +all operations <em>wrap around</em>, +according to the usual rules of two-complement arithmetic. +(In other words, +they return the unique representable integer +that is equal modulo <em>2<sup>64</sup></em> to the mathematical result.) + + + +<h3>3.4.2 – <a name="3.4.2">Bitwise Operators</a></h3><p> +Lua supports the following bitwise operators: + +<ul> +<li><b><code>&</code>: </b>bitwise AND</li> +<li><b><code>|</code>: </b>bitwise OR</li> +<li><b><code>~</code>: </b>bitwise exclusive OR</li> +<li><b><code>>></code>: </b>right shift</li> +<li><b><code><<</code>: </b>left shift</li> +<li><b><code>~</code>: </b>unary bitwise NOT</li> +</ul> + +<p> +All bitwise operations convert its operands to integers +(see <a href="#3.4.3">§3.4.3</a>), +operate on all bits of those integers, +and result in an integer. + + +<p> +Both right and left shifts fill the vacant bits with zeros. +Negative displacements shift to the other direction; +displacements with absolute values equal to or higher than +the number of bits in an integer +result in zero (as all bits are shifted out). + + + + + +<h3>3.4.3 – <a name="3.4.3">Coercions and Conversions</a></h3><p> +Lua provides some automatic conversions between some +types and representations at run time. +Bitwise operators always convert float operands to integers. +Exponentiation and float division +always convert integer operands to floats. +All other arithmetic operations applied to mixed numbers +(integers and floats) convert the integer operand to a float; +this is called the <em>usual rule</em>. +The C API also converts both integers to floats and +floats to integers, as needed. +Moreover, string concatenation accepts numbers as arguments, +besides strings. + + +<p> +Lua also converts strings to numbers, +whenever a number is expected. + + +<p> +In a conversion from integer to float, +if the integer value has an exact representation as a float, +that is the result. +Otherwise, +the conversion gets the nearest higher or +the nearest lower representable value. +This kind of conversion never fails. + + +<p> +The conversion from float to integer +checks whether the float has an exact representation as an integer +(that is, the float has an integral value and +it is in the range of integer representation). +If it does, that representation is the result. +Otherwise, the conversion fails. + + +<p> +The conversion from strings to numbers goes as follows: +First, the string is converted to an integer or a float, +following its syntax and the rules of the Lua lexer. +(The string may have also leading and trailing spaces and a sign.) +Then, the resulting number (float or integer) +is converted to the type (float or integer) required by the context +(e.g., the operation that forced the conversion). + + +<p> +All conversions from strings to numbers +accept both a dot and the current locale mark +as the radix character. +(The Lua lexer, however, accepts only a dot.) + + +<p> +The conversion from numbers to strings uses a +non-specified human-readable format. +For complete control over how numbers are converted to strings, +use the <code>format</code> function from the string library +(see <a href="#pdf-string.format"><code>string.format</code></a>). + + + + + +<h3>3.4.4 – <a name="3.4.4">Relational Operators</a></h3><p> +Lua supports the following relational operators: + +<ul> +<li><b><code>==</code>: </b>equality</li> +<li><b><code>~=</code>: </b>inequality</li> +<li><b><code><</code>: </b>less than</li> +<li><b><code>></code>: </b>greater than</li> +<li><b><code><=</code>: </b>less or equal</li> +<li><b><code>>=</code>: </b>greater or equal</li> +</ul><p> +These operators always result in <b>false</b> or <b>true</b>. + + +<p> +Equality (<code>==</code>) first compares the type of its operands. +If the types are different, then the result is <b>false</b>. +Otherwise, the values of the operands are compared. +Strings are compared in the obvious way. +Numbers are equal if they denote the same mathematical value. + + +<p> +Tables, userdata, and threads +are compared by reference: +two objects are considered equal only if they are the same object. +Every time you create a new object +(a table, userdata, or thread), +this new object is different from any previously existing object. +A closure is always equal to itself. +Closures with any detectable difference +(different behavior, different definition) are always different. +Closures created at different times but with no detectable differences +may be classified as equal or not +(depending on internal caching details). + + +<p> +You can change the way that Lua compares tables and userdata +by using the "eq" metamethod (see <a href="#2.4">§2.4</a>). + + +<p> +Equality comparisons do not convert strings to numbers +or vice versa. +Thus, <code>"0"==0</code> evaluates to <b>false</b>, +and <code>t[0]</code> and <code>t["0"]</code> denote different +entries in a table. + + +<p> +The operator <code>~=</code> is exactly the negation of equality (<code>==</code>). + + +<p> +The order operators work as follows. +If both arguments are numbers, +then they are compared according to their mathematical values +(regardless of their subtypes). +Otherwise, if both arguments are strings, +then their values are compared according to the current locale. +Otherwise, Lua tries to call the "lt" or the "le" +metamethod (see <a href="#2.4">§2.4</a>). +A comparison <code>a > b</code> is translated to <code>b < a</code> +and <code>a >= b</code> is translated to <code>b <= a</code>. + + +<p> +Following the IEEE 754 standard, +NaN is considered neither smaller than, +nor equal to, nor greater than any value (including itself). + + + + + +<h3>3.4.5 – <a name="3.4.5">Logical Operators</a></h3><p> +The logical operators in Lua are +<b>and</b>, <b>or</b>, and <b>not</b>. +Like the control structures (see <a href="#3.3.4">§3.3.4</a>), +all logical operators consider both <b>false</b> and <b>nil</b> as false +and anything else as true. + + +<p> +The negation operator <b>not</b> always returns <b>false</b> or <b>true</b>. +The conjunction operator <b>and</b> returns its first argument +if this value is <b>false</b> or <b>nil</b>; +otherwise, <b>and</b> returns its second argument. +The disjunction operator <b>or</b> returns its first argument +if this value is different from <b>nil</b> and <b>false</b>; +otherwise, <b>or</b> returns its second argument. +Both <b>and</b> and <b>or</b> use short-circuit evaluation; +that is, +the second operand is evaluated only if necessary. +Here are some examples: + +<pre> + 10 or 20 --> 10 + 10 or error() --> 10 + nil or "a" --> "a" + nil and 10 --> nil + false and error() --> false + false and nil --> false + false or nil --> nil + 10 and 20 --> 20 +</pre><p> +(In this manual, +<code>--></code> indicates the result of the preceding expression.) + + + + + +<h3>3.4.6 – <a name="3.4.6">Concatenation</a></h3><p> +The string concatenation operator in Lua is +denoted by two dots ('<code>..</code>'). +If both operands are strings or numbers, then they are converted to +strings according to the rules described in <a href="#3.4.3">§3.4.3</a>. +Otherwise, the <code>__concat</code> metamethod is called (see <a href="#2.4">§2.4</a>). + + + + + +<h3>3.4.7 – <a name="3.4.7">The Length Operator</a></h3> + +<p> +The length operator is denoted by the unary prefix operator <code>#</code>. + + +<p> +The length of a string is its number of bytes +(that is, the usual meaning of string length when each +character is one byte). + + +<p> +The length operator applied on a table +returns a border in that table. +A <em>border</em> in a table <code>t</code> is any natural number +that satisfies the following condition: + +<pre> + (border == 0 or t[border] ~= nil) and t[border + 1] == nil +</pre><p> +In words, +a border is any (natural) index in a table +where a non-nil value is followed by a nil value +(or zero, when index 1 is nil). + + +<p> +A table with exactly one border is called a <em>sequence</em>. +For instance, the table <code>{10, 20, 30, 40, 50}</code> is a sequence, +as it has only one border (5). +The table <code>{10, 20, 30, nil, 50}</code> has two borders (3 and 5), +and therefore it is not a sequence. +The table <code>{nil, 20, 30, nil, nil, 60, nil}</code> +has three borders (0, 3, and 6), +so it is not a sequence, too. +The table <code>{}</code> is a sequence with border 0. +Note that non-natural keys do not interfere +with whether a table is a sequence. + + +<p> +When <code>t</code> is a sequence, +<code>#t</code> returns its only border, +which corresponds to the intuitive notion of the length of the sequence. +When <code>t</code> is not a sequence, +<code>#t</code> can return any of its borders. +(The exact one depends on details of +the internal representation of the table, +which in turn can depend on how the table was populated and +the memory addresses of its non-numeric keys.) + + +<p> +The computation of the length of a table +has a guaranteed worst time of <em>O(log n)</em>, +where <em>n</em> is the largest natural key in the table. + + +<p> +A program can modify the behavior of the length operator for +any value but strings through the <code>__len</code> metamethod (see <a href="#2.4">§2.4</a>). + + + + + +<h3>3.4.8 – <a name="3.4.8">Precedence</a></h3><p> +Operator precedence in Lua follows the table below, +from lower to higher priority: + +<pre> + or + and + < > <= >= ~= == + | + ~ + & + << >> + .. + + - + * / // % + unary operators (not # - ~) + ^ +</pre><p> +As usual, +you can use parentheses to change the precedences of an expression. +The concatenation ('<code>..</code>') and exponentiation ('<code>^</code>') +operators are right associative. +All other binary operators are left associative. + + + + + +<h3>3.4.9 – <a name="3.4.9">Table Constructors</a></h3><p> +Table constructors are expressions that create tables. +Every time a constructor is evaluated, a new table is created. +A constructor can be used to create an empty table +or to create a table and initialize some of its fields. +The general syntax for constructors is + +<pre> + tableconstructor ::= ‘<b>{</b>’ [fieldlist] ‘<b>}</b>’ + fieldlist ::= field {fieldsep field} [fieldsep] + field ::= ‘<b>[</b>’ exp ‘<b>]</b>’ ‘<b>=</b>’ exp | Name ‘<b>=</b>’ exp | exp + fieldsep ::= ‘<b>,</b>’ | ‘<b>;</b>’ +</pre> + +<p> +Each field of the form <code>[exp1] = exp2</code> adds to the new table an entry +with key <code>exp1</code> and value <code>exp2</code>. +A field of the form <code>name = exp</code> is equivalent to +<code>["name"] = exp</code>. +Finally, fields of the form <code>exp</code> are equivalent to +<code>[i] = exp</code>, where <code>i</code> are consecutive integers +starting with 1. +Fields in the other formats do not affect this counting. +For example, + +<pre> + a = { [f(1)] = g; "x", "y"; x = 1, f(x), [30] = 23; 45 } +</pre><p> +is equivalent to + +<pre> + do + local t = {} + t[f(1)] = g + t[1] = "x" -- 1st exp + t[2] = "y" -- 2nd exp + t.x = 1 -- t["x"] = 1 + t[3] = f(x) -- 3rd exp + t[30] = 23 + t[4] = 45 -- 4th exp + a = t + end +</pre> + +<p> +The order of the assignments in a constructor is undefined. +(This order would be relevant only when there are repeated keys.) + + +<p> +If the last field in the list has the form <code>exp</code> +and the expression is a function call or a vararg expression, +then all values returned by this expression enter the list consecutively +(see <a href="#3.4.10">§3.4.10</a>). + + +<p> +The field list can have an optional trailing separator, +as a convenience for machine-generated code. + + + + + +<h3>3.4.10 – <a name="3.4.10">Function Calls</a></h3><p> +A function call in Lua has the following syntax: + +<pre> + functioncall ::= prefixexp args +</pre><p> +In a function call, +first prefixexp and args are evaluated. +If the value of prefixexp has type <em>function</em>, +then this function is called +with the given arguments. +Otherwise, the prefixexp "call" metamethod is called, +having as first argument the value of prefixexp, +followed by the original call arguments +(see <a href="#2.4">§2.4</a>). + + +<p> +The form + +<pre> + functioncall ::= prefixexp ‘<b>:</b>’ Name args +</pre><p> +can be used to call "methods". +A call <code>v:name(<em>args</em>)</code> +is syntactic sugar for <code>v.name(v,<em>args</em>)</code>, +except that <code>v</code> is evaluated only once. + + +<p> +Arguments have the following syntax: + +<pre> + args ::= ‘<b>(</b>’ [explist] ‘<b>)</b>’ + args ::= tableconstructor + args ::= LiteralString +</pre><p> +All argument expressions are evaluated before the call. +A call of the form <code>f{<em>fields</em>}</code> is +syntactic sugar for <code>f({<em>fields</em>})</code>; +that is, the argument list is a single new table. +A call of the form <code>f'<em>string</em>'</code> +(or <code>f"<em>string</em>"</code> or <code>f[[<em>string</em>]]</code>) +is syntactic sugar for <code>f('<em>string</em>')</code>; +that is, the argument list is a single literal string. + + +<p> +A call of the form <code>return <em>functioncall</em></code> is called +a <em>tail call</em>. +Lua implements <em>proper tail calls</em> +(or <em>proper tail recursion</em>): +in a tail call, +the called function reuses the stack entry of the calling function. +Therefore, there is no limit on the number of nested tail calls that +a program can execute. +However, a tail call erases any debug information about the +calling function. +Note that a tail call only happens with a particular syntax, +where the <b>return</b> has one single function call as argument; +this syntax makes the calling function return exactly +the returns of the called function. +So, none of the following examples are tail calls: + +<pre> + return (f(x)) -- results adjusted to 1 + return 2 * f(x) + return x, f(x) -- additional results + f(x); return -- results discarded + return x or f(x) -- results adjusted to 1 +</pre> + + + + +<h3>3.4.11 – <a name="3.4.11">Function Definitions</a></h3> + +<p> +The syntax for function definition is + +<pre> + functiondef ::= <b>function</b> funcbody + funcbody ::= ‘<b>(</b>’ [parlist] ‘<b>)</b>’ block <b>end</b> +</pre> + +<p> +The following syntactic sugar simplifies function definitions: + +<pre> + stat ::= <b>function</b> funcname funcbody + stat ::= <b>local</b> <b>function</b> Name funcbody + funcname ::= Name {‘<b>.</b>’ Name} [‘<b>:</b>’ Name] +</pre><p> +The statement + +<pre> + function f () <em>body</em> end +</pre><p> +translates to + +<pre> + f = function () <em>body</em> end +</pre><p> +The statement + +<pre> + function t.a.b.c.f () <em>body</em> end +</pre><p> +translates to + +<pre> + t.a.b.c.f = function () <em>body</em> end +</pre><p> +The statement + +<pre> + local function f () <em>body</em> end +</pre><p> +translates to + +<pre> + local f; f = function () <em>body</em> end +</pre><p> +not to + +<pre> + local f = function () <em>body</em> end +</pre><p> +(This only makes a difference when the body of the function +contains references to <code>f</code>.) + + +<p> +A function definition is an executable expression, +whose value has type <em>function</em>. +When Lua precompiles a chunk, +all its function bodies are precompiled too. +Then, whenever Lua executes the function definition, +the function is <em>instantiated</em> (or <em>closed</em>). +This function instance (or <em>closure</em>) +is the final value of the expression. + + +<p> +Parameters act as local variables that are +initialized with the argument values: + +<pre> + parlist ::= namelist [‘<b>,</b>’ ‘<b>...</b>’] | ‘<b>...</b>’ +</pre><p> +When a function is called, +the list of arguments is adjusted to +the length of the list of parameters, +unless the function is a <em>vararg function</em>, +which is indicated by three dots ('<code>...</code>') +at the end of its parameter list. +A vararg function does not adjust its argument list; +instead, it collects all extra arguments and supplies them +to the function through a <em>vararg expression</em>, +which is also written as three dots. +The value of this expression is a list of all actual extra arguments, +similar to a function with multiple results. +If a vararg expression is used inside another expression +or in the middle of a list of expressions, +then its return list is adjusted to one element. +If the expression is used as the last element of a list of expressions, +then no adjustment is made +(unless that last expression is enclosed in parentheses). + + +<p> +As an example, consider the following definitions: + +<pre> + function f(a, b) end + function g(a, b, ...) end + function r() return 1,2,3 end +</pre><p> +Then, we have the following mapping from arguments to parameters and +to the vararg expression: + +<pre> + CALL PARAMETERS + + f(3) a=3, b=nil + f(3, 4) a=3, b=4 + f(3, 4, 5) a=3, b=4 + f(r(), 10) a=1, b=10 + f(r()) a=1, b=2 + + g(3) a=3, b=nil, ... --> (nothing) + g(3, 4) a=3, b=4, ... --> (nothing) + g(3, 4, 5, 8) a=3, b=4, ... --> 5 8 + g(5, r()) a=5, b=1, ... --> 2 3 +</pre> + +<p> +Results are returned using the <b>return</b> statement (see <a href="#3.3.4">§3.3.4</a>). +If control reaches the end of a function +without encountering a <b>return</b> statement, +then the function returns with no results. + + +<p> + +There is a system-dependent limit on the number of values +that a function may return. +This limit is guaranteed to be larger than 1000. + + +<p> +The <em>colon</em> syntax +is used for defining <em>methods</em>, +that is, functions that have an implicit extra parameter <code>self</code>. +Thus, the statement + +<pre> + function t.a.b.c:f (<em>params</em>) <em>body</em> end +</pre><p> +is syntactic sugar for + +<pre> + t.a.b.c.f = function (self, <em>params</em>) <em>body</em> end +</pre> + + + + + + +<h2>3.5 – <a name="3.5">Visibility Rules</a></h2> + +<p> + +Lua is a lexically scoped language. +The scope of a local variable begins at the first statement after +its declaration and lasts until the last non-void statement +of the innermost block that includes the declaration. +Consider the following example: + +<pre> + x = 10 -- global variable + do -- new block + local x = x -- new 'x', with value 10 + print(x) --> 10 + x = x+1 + do -- another block + local x = x+1 -- another 'x' + print(x) --> 12 + end + print(x) --> 11 + end + print(x) --> 10 (the global one) +</pre> + +<p> +Notice that, in a declaration like <code>local x = x</code>, +the new <code>x</code> being declared is not in scope yet, +and so the second <code>x</code> refers to the outside variable. + + +<p> +Because of the lexical scoping rules, +local variables can be freely accessed by functions +defined inside their scope. +A local variable used by an inner function is called +an <em>upvalue</em>, or <em>external local variable</em>, +inside the inner function. + + +<p> +Notice that each execution of a <b>local</b> statement +defines new local variables. +Consider the following example: + +<pre> + a = {} + local x = 20 + for i=1,10 do + local y = 0 + a[i] = function () y=y+1; return x+y end + end +</pre><p> +The loop creates ten closures +(that is, ten instances of the anonymous function). +Each of these closures uses a different <code>y</code> variable, +while all of them share the same <code>x</code>. + + + + + +<h1>4 – <a name="4">The Application Program Interface</a></h1> + +<p> + +This section describes the C API for Lua, that is, +the set of C functions available to the host program to communicate +with Lua. +All API functions and related types and constants +are declared in the header file <a name="pdf-lua.h"><code>lua.h</code></a>. + + +<p> +Even when we use the term "function", +any facility in the API may be provided as a macro instead. +Except where stated otherwise, +all such macros use each of their arguments exactly once +(except for the first argument, which is always a Lua state), +and so do not generate any hidden side-effects. + + +<p> +As in most C libraries, +the Lua API functions do not check their arguments for validity or consistency. +However, you can change this behavior by compiling Lua +with the macro <a name="pdf-LUA_USE_APICHECK"><code>LUA_USE_APICHECK</code></a> defined. + + +<p> +The Lua library is fully reentrant: +it has no global variables. +It keeps all information it needs in a dynamic structure, +called the <em>Lua state</em>. + + +<p> +Each Lua state has one or more threads, +which correspond to independent, cooperative lines of execution. +The type <a href="#lua_State"><code>lua_State</code></a> (despite its name) refers to a thread. +(Indirectly, through the thread, it also refers to the +Lua state associated to the thread.) + + +<p> +A pointer to a thread must be passed as the first argument to +every function in the library, except to <a href="#lua_newstate"><code>lua_newstate</code></a>, +which creates a Lua state from scratch and returns a pointer +to the <em>main thread</em> in the new state. + + + +<h2>4.1 – <a name="4.1">The Stack</a></h2> + +<p> +Lua uses a <em>virtual stack</em> to pass values to and from C. +Each element in this stack represents a Lua value +(<b>nil</b>, number, string, etc.). +Functions in the API can access this stack through the +Lua state parameter that they receive. + + +<p> +Whenever Lua calls C, the called function gets a new stack, +which is independent of previous stacks and of stacks of +C functions that are still active. +This stack initially contains any arguments to the C function +and it is where the C function can store temporary +Lua values and must push its results +to be returned to the caller (see <a href="#lua_CFunction"><code>lua_CFunction</code></a>). + + +<p> +For convenience, +most query operations in the API do not follow a strict stack discipline. +Instead, they can refer to any element in the stack +by using an <em>index</em>: +A positive index represents an absolute stack position +(starting at 1); +a negative index represents an offset relative to the top of the stack. +More specifically, if the stack has <em>n</em> elements, +then index 1 represents the first element +(that is, the element that was pushed onto the stack first) +and +index <em>n</em> represents the last element; +index -1 also represents the last element +(that is, the element at the top) +and index <em>-n</em> represents the first element. + + + + + +<h2>4.2 – <a name="4.2">Stack Size</a></h2> + +<p> +When you interact with the Lua API, +you are responsible for ensuring consistency. +In particular, +<em>you are responsible for controlling stack overflow</em>. +You can use the function <a href="#lua_checkstack"><code>lua_checkstack</code></a> +to ensure that the stack has enough space for pushing new elements. + + +<p> +Whenever Lua calls C, +it ensures that the stack has space for +at least <a name="pdf-LUA_MINSTACK"><code>LUA_MINSTACK</code></a> extra slots. +<code>LUA_MINSTACK</code> is defined as 20, +so that usually you do not have to worry about stack space +unless your code has loops pushing elements onto the stack. + + +<p> +When you call a Lua function +without a fixed number of results (see <a href="#lua_call"><code>lua_call</code></a>), +Lua ensures that the stack has enough space for all results, +but it does not ensure any extra space. +So, before pushing anything in the stack after such a call +you should use <a href="#lua_checkstack"><code>lua_checkstack</code></a>. + + + + + +<h2>4.3 – <a name="4.3">Valid and Acceptable Indices</a></h2> + +<p> +Any function in the API that receives stack indices +works only with <em>valid indices</em> or <em>acceptable indices</em>. + + +<p> +A <em>valid index</em> is an index that refers to a +position that stores a modifiable Lua value. +It comprises stack indices between 1 and the stack top +(<code>1 ≤ abs(index) ≤ top</code>) + +plus <em>pseudo-indices</em>, +which represent some positions that are accessible to C code +but that are not in the stack. +Pseudo-indices are used to access the registry (see <a href="#4.5">§4.5</a>) +and the upvalues of a C function (see <a href="#4.4">§4.4</a>). + + +<p> +Functions that do not need a specific mutable position, +but only a value (e.g., query functions), +can be called with acceptable indices. +An <em>acceptable index</em> can be any valid index, +but it also can be any positive index after the stack top +within the space allocated for the stack, +that is, indices up to the stack size. +(Note that 0 is never an acceptable index.) +Except when noted otherwise, +functions in the API work with acceptable indices. + + +<p> +Acceptable indices serve to avoid extra tests +against the stack top when querying the stack. +For instance, a C function can query its third argument +without the need to first check whether there is a third argument, +that is, without the need to check whether 3 is a valid index. + + +<p> +For functions that can be called with acceptable indices, +any non-valid index is treated as if it +contains a value of a virtual type <a name="pdf-LUA_TNONE"><code>LUA_TNONE</code></a>, +which behaves like a nil value. + + + + + +<h2>4.4 – <a name="4.4">C Closures</a></h2> + +<p> +When a C function is created, +it is possible to associate some values with it, +thus creating a <em>C closure</em> +(see <a href="#lua_pushcclosure"><code>lua_pushcclosure</code></a>); +these values are called <em>upvalues</em> and are +accessible to the function whenever it is called. + + +<p> +Whenever a C function is called, +its upvalues are located at specific pseudo-indices. +These pseudo-indices are produced by the macro +<a href="#lua_upvalueindex"><code>lua_upvalueindex</code></a>. +The first upvalue associated with a function is at index +<code>lua_upvalueindex(1)</code>, and so on. +Any access to <code>lua_upvalueindex(<em>n</em>)</code>, +where <em>n</em> is greater than the number of upvalues of the +current function +(but not greater than 256, +which is one plus the maximum number of upvalues in a closure), +produces an acceptable but invalid index. + + + + + +<h2>4.5 – <a name="4.5">Registry</a></h2> + +<p> +Lua provides a <em>registry</em>, +a predefined table that can be used by any C code to +store whatever Lua values it needs to store. +The registry table is always located at pseudo-index +<a name="pdf-LUA_REGISTRYINDEX"><code>LUA_REGISTRYINDEX</code></a>. +Any C library can store data into this table, +but it must take care to choose keys +that are different from those used +by other libraries, to avoid collisions. +Typically, you should use as key a string containing your library name, +or a light userdata with the address of a C object in your code, +or any Lua object created by your code. +As with variable names, +string keys starting with an underscore followed by +uppercase letters are reserved for Lua. + + +<p> +The integer keys in the registry are used +by the reference mechanism (see <a href="#luaL_ref"><code>luaL_ref</code></a>) +and by some predefined values. +Therefore, integer keys must not be used for other purposes. + + +<p> +When you create a new Lua state, +its registry comes with some predefined values. +These predefined values are indexed with integer keys +defined as constants in <code>lua.h</code>. +The following constants are defined: + +<ul> +<li><b><a name="pdf-LUA_RIDX_MAINTHREAD"><code>LUA_RIDX_MAINTHREAD</code></a>: </b> At this index the registry has +the main thread of the state. +(The main thread is the one created together with the state.) +</li> + +<li><b><a name="pdf-LUA_RIDX_GLOBALS"><code>LUA_RIDX_GLOBALS</code></a>: </b> At this index the registry has +the global environment. +</li> +</ul> + + + + +<h2>4.6 – <a name="4.6">Error Handling in C</a></h2> + +<p> +Internally, Lua uses the C <code>longjmp</code> facility to handle errors. +(Lua will use exceptions if you compile it as C++; +search for <code>LUAI_THROW</code> in the source code for details.) +When Lua faces any error +(such as a memory allocation error or a type error) +it <em>raises</em> an error; +that is, it does a long jump. +A <em>protected environment</em> uses <code>setjmp</code> +to set a recovery point; +any error jumps to the most recent active recovery point. + + +<p> +Inside a C function you can raise an error by calling <a href="#lua_error"><code>lua_error</code></a>. + + +<p> +Most functions in the API can raise an error, +for instance due to a memory allocation error. +The documentation for each function indicates whether +it can raise errors. + + +<p> +If an error happens outside any protected environment, +Lua calls a <em>panic function</em> (see <a href="#lua_atpanic"><code>lua_atpanic</code></a>) +and then calls <code>abort</code>, +thus exiting the host application. +Your panic function can avoid this exit by +never returning +(e.g., doing a long jump to your own recovery point outside Lua). + + +<p> +The panic function, +as its name implies, +is a mechanism of last resort. +Programs should avoid it. +As a general rule, +when a C function is called by Lua with a Lua state, +it can do whatever it wants on that Lua state, +as it should be already protected. +However, +when C code operates on other Lua states +(e.g., a Lua argument to the function, +a Lua state stored in the registry, or +the result of <a href="#lua_newthread"><code>lua_newthread</code></a>), +it should use them only in API calls that cannot raise errors. + + +<p> +The panic function runs as if it were a message handler (see <a href="#2.3">§2.3</a>); +in particular, the error object is at the top of the stack. +However, there is no guarantee about stack space. +To push anything on the stack, +the panic function must first check the available space (see <a href="#4.2">§4.2</a>). + + + + + +<h2>4.7 – <a name="4.7">Handling Yields in C</a></h2> + +<p> +Internally, Lua uses the C <code>longjmp</code> facility to yield a coroutine. +Therefore, if a C function <code>foo</code> calls an API function +and this API function yields +(directly or indirectly by calling another function that yields), +Lua cannot return to <code>foo</code> any more, +because the <code>longjmp</code> removes its frame from the C stack. + + +<p> +To avoid this kind of problem, +Lua raises an error whenever it tries to yield across an API call, +except for three functions: +<a href="#lua_yieldk"><code>lua_yieldk</code></a>, <a href="#lua_callk"><code>lua_callk</code></a>, and <a href="#lua_pcallk"><code>lua_pcallk</code></a>. +All those functions receive a <em>continuation function</em> +(as a parameter named <code>k</code>) to continue execution after a yield. + + +<p> +We need to set some terminology to explain continuations. +We have a C function called from Lua which we will call +the <em>original function</em>. +This original function then calls one of those three functions in the C API, +which we will call the <em>callee function</em>, +that then yields the current thread. +(This can happen when the callee function is <a href="#lua_yieldk"><code>lua_yieldk</code></a>, +or when the callee function is either <a href="#lua_callk"><code>lua_callk</code></a> or <a href="#lua_pcallk"><code>lua_pcallk</code></a> +and the function called by them yields.) + + +<p> +Suppose the running thread yields while executing the callee function. +After the thread resumes, +it eventually will finish running the callee function. +However, +the callee function cannot return to the original function, +because its frame in the C stack was destroyed by the yield. +Instead, Lua calls a <em>continuation function</em>, +which was given as an argument to the callee function. +As the name implies, +the continuation function should continue the task +of the original function. + + +<p> +As an illustration, consider the following function: + +<pre> + int original_function (lua_State *L) { + ... /* code 1 */ + status = lua_pcall(L, n, m, h); /* calls Lua */ + ... /* code 2 */ + } +</pre><p> +Now we want to allow +the Lua code being run by <a href="#lua_pcall"><code>lua_pcall</code></a> to yield. +First, we can rewrite our function like here: + +<pre> + int k (lua_State *L, int status, lua_KContext ctx) { + ... /* code 2 */ + } + + int original_function (lua_State *L) { + ... /* code 1 */ + return k(L, lua_pcall(L, n, m, h), ctx); + } +</pre><p> +In the above code, +the new function <code>k</code> is a +<em>continuation function</em> (with type <a href="#lua_KFunction"><code>lua_KFunction</code></a>), +which should do all the work that the original function +was doing after calling <a href="#lua_pcall"><code>lua_pcall</code></a>. +Now, we must inform Lua that it must call <code>k</code> if the Lua code +being executed by <a href="#lua_pcall"><code>lua_pcall</code></a> gets interrupted in some way +(errors or yielding), +so we rewrite the code as here, +replacing <a href="#lua_pcall"><code>lua_pcall</code></a> by <a href="#lua_pcallk"><code>lua_pcallk</code></a>: + +<pre> + int original_function (lua_State *L) { + ... /* code 1 */ + return k(L, lua_pcallk(L, n, m, h, ctx2, k), ctx1); + } +</pre><p> +Note the external, explicit call to the continuation: +Lua will call the continuation only if needed, that is, +in case of errors or resuming after a yield. +If the called function returns normally without ever yielding, +<a href="#lua_pcallk"><code>lua_pcallk</code></a> (and <a href="#lua_callk"><code>lua_callk</code></a>) will also return normally. +(Of course, instead of calling the continuation in that case, +you can do the equivalent work directly inside the original function.) + + +<p> +Besides the Lua state, +the continuation function has two other parameters: +the final status of the call plus the context value (<code>ctx</code>) that +was passed originally to <a href="#lua_pcallk"><code>lua_pcallk</code></a>. +(Lua does not use this context value; +it only passes this value from the original function to the +continuation function.) +For <a href="#lua_pcallk"><code>lua_pcallk</code></a>, +the status is the same value that would be returned by <a href="#lua_pcallk"><code>lua_pcallk</code></a>, +except that it is <a href="#pdf-LUA_YIELD"><code>LUA_YIELD</code></a> when being executed after a yield +(instead of <a href="#pdf-LUA_OK"><code>LUA_OK</code></a>). +For <a href="#lua_yieldk"><code>lua_yieldk</code></a> and <a href="#lua_callk"><code>lua_callk</code></a>, +the status is always <a href="#pdf-LUA_YIELD"><code>LUA_YIELD</code></a> when Lua calls the continuation. +(For these two functions, +Lua will not call the continuation in case of errors, +because they do not handle errors.) +Similarly, when using <a href="#lua_callk"><code>lua_callk</code></a>, +you should call the continuation function +with <a href="#pdf-LUA_OK"><code>LUA_OK</code></a> as the status. +(For <a href="#lua_yieldk"><code>lua_yieldk</code></a>, there is not much point in calling +directly the continuation function, +because <a href="#lua_yieldk"><code>lua_yieldk</code></a> usually does not return.) + + +<p> +Lua treats the continuation function as if it were the original function. +The continuation function receives the same Lua stack +from the original function, +in the same state it would be if the callee function had returned. +(For instance, +after a <a href="#lua_callk"><code>lua_callk</code></a> the function and its arguments are +removed from the stack and replaced by the results from the call.) +It also has the same upvalues. +Whatever it returns is handled by Lua as if it were the return +of the original function. + + + + + +<h2>4.8 – <a name="4.8">Functions and Types</a></h2> + +<p> +Here we list all functions and types from the C API in +alphabetical order. +Each function has an indicator like this: +<span class="apii">[-o, +p, <em>x</em>]</span> + + +<p> +The first field, <code>o</code>, +is how many elements the function pops from the stack. +The second field, <code>p</code>, +is how many elements the function pushes onto the stack. +(Any function always pushes its results after popping its arguments.) +A field in the form <code>x|y</code> means the function can push (or pop) +<code>x</code> or <code>y</code> elements, +depending on the situation; +an interrogation mark '<code>?</code>' means that +we cannot know how many elements the function pops/pushes +by looking only at its arguments +(e.g., they may depend on what is on the stack). +The third field, <code>x</code>, +tells whether the function may raise errors: +'<code>-</code>' means the function never raises any error; +'<code>m</code>' means the function may raise out-of-memory errors +and errors running a <code>__gc</code> metamethod; +'<code>e</code>' means the function may raise any errors +(it can run arbitrary Lua code, +either directly or through metamethods); +'<code>v</code>' means the function may raise an error on purpose. + + + +<hr><h3><a name="lua_absindex"><code>lua_absindex</code></a></h3><p> +<span class="apii">[-0, +0, –]</span> +<pre>int lua_absindex (lua_State *L, int idx);</pre> + +<p> +Converts the acceptable index <code>idx</code> +into an equivalent absolute index +(that is, one that does not depend on the stack top). + + + + + +<hr><h3><a name="lua_Alloc"><code>lua_Alloc</code></a></h3> +<pre>typedef void * (*lua_Alloc) (void *ud, + void *ptr, + size_t osize, + size_t nsize);</pre> + +<p> +The type of the memory-allocation function used by Lua states. +The allocator function must provide a +functionality similar to <code>realloc</code>, +but not exactly the same. +Its arguments are +<code>ud</code>, an opaque pointer passed to <a href="#lua_newstate"><code>lua_newstate</code></a>; +<code>ptr</code>, a pointer to the block being allocated/reallocated/freed; +<code>osize</code>, the original size of the block or some code about what +is being allocated; +and <code>nsize</code>, the new size of the block. + + +<p> +When <code>ptr</code> is not <code>NULL</code>, +<code>osize</code> is the size of the block pointed by <code>ptr</code>, +that is, the size given when it was allocated or reallocated. + + +<p> +When <code>ptr</code> is <code>NULL</code>, +<code>osize</code> encodes the kind of object that Lua is allocating. +<code>osize</code> is any of +<a href="#pdf-LUA_TSTRING"><code>LUA_TSTRING</code></a>, <a href="#pdf-LUA_TTABLE"><code>LUA_TTABLE</code></a>, <a href="#pdf-LUA_TFUNCTION"><code>LUA_TFUNCTION</code></a>, +<a href="#pdf-LUA_TUSERDATA"><code>LUA_TUSERDATA</code></a>, or <a href="#pdf-LUA_TTHREAD"><code>LUA_TTHREAD</code></a> when (and only when) +Lua is creating a new object of that type. +When <code>osize</code> is some other value, +Lua is allocating memory for something else. + + +<p> +Lua assumes the following behavior from the allocator function: + + +<p> +When <code>nsize</code> is zero, +the allocator must behave like <code>free</code> +and return <code>NULL</code>. + + +<p> +When <code>nsize</code> is not zero, +the allocator must behave like <code>realloc</code>. +The allocator returns <code>NULL</code> +if and only if it cannot fulfill the request. +Lua assumes that the allocator never fails when +<code>osize >= nsize</code>. + + +<p> +Here is a simple implementation for the allocator function. +It is used in the auxiliary library by <a href="#luaL_newstate"><code>luaL_newstate</code></a>. + +<pre> + static void *l_alloc (void *ud, void *ptr, size_t osize, + size_t nsize) { + (void)ud; (void)osize; /* not used */ + if (nsize == 0) { + free(ptr); + return NULL; + } + else + return realloc(ptr, nsize); + } +</pre><p> +Note that Standard C ensures +that <code>free(NULL)</code> has no effect and that +<code>realloc(NULL,size)</code> is equivalent to <code>malloc(size)</code>. +This code assumes that <code>realloc</code> does not fail when shrinking a block. +(Although Standard C does not ensure this behavior, +it seems to be a safe assumption.) + + + + + +<hr><h3><a name="lua_arith"><code>lua_arith</code></a></h3><p> +<span class="apii">[-(2|1), +1, <em>e</em>]</span> +<pre>void lua_arith (lua_State *L, int op);</pre> + +<p> +Performs an arithmetic or bitwise operation over the two values +(or one, in the case of negations) +at the top of the stack, +with the value at the top being the second operand, +pops these values, and pushes the result of the operation. +The function follows the semantics of the corresponding Lua operator +(that is, it may call metamethods). + + +<p> +The value of <code>op</code> must be one of the following constants: + +<ul> + +<li><b><a name="pdf-LUA_OPADD"><code>LUA_OPADD</code></a>: </b> performs addition (<code>+</code>)</li> +<li><b><a name="pdf-LUA_OPSUB"><code>LUA_OPSUB</code></a>: </b> performs subtraction (<code>-</code>)</li> +<li><b><a name="pdf-LUA_OPMUL"><code>LUA_OPMUL</code></a>: </b> performs multiplication (<code>*</code>)</li> +<li><b><a name="pdf-LUA_OPDIV"><code>LUA_OPDIV</code></a>: </b> performs float division (<code>/</code>)</li> +<li><b><a name="pdf-LUA_OPIDIV"><code>LUA_OPIDIV</code></a>: </b> performs floor division (<code>//</code>)</li> +<li><b><a name="pdf-LUA_OPMOD"><code>LUA_OPMOD</code></a>: </b> performs modulo (<code>%</code>)</li> +<li><b><a name="pdf-LUA_OPPOW"><code>LUA_OPPOW</code></a>: </b> performs exponentiation (<code>^</code>)</li> +<li><b><a name="pdf-LUA_OPUNM"><code>LUA_OPUNM</code></a>: </b> performs mathematical negation (unary <code>-</code>)</li> +<li><b><a name="pdf-LUA_OPBNOT"><code>LUA_OPBNOT</code></a>: </b> performs bitwise NOT (<code>~</code>)</li> +<li><b><a name="pdf-LUA_OPBAND"><code>LUA_OPBAND</code></a>: </b> performs bitwise AND (<code>&</code>)</li> +<li><b><a name="pdf-LUA_OPBOR"><code>LUA_OPBOR</code></a>: </b> performs bitwise OR (<code>|</code>)</li> +<li><b><a name="pdf-LUA_OPBXOR"><code>LUA_OPBXOR</code></a>: </b> performs bitwise exclusive OR (<code>~</code>)</li> +<li><b><a name="pdf-LUA_OPSHL"><code>LUA_OPSHL</code></a>: </b> performs left shift (<code><<</code>)</li> +<li><b><a name="pdf-LUA_OPSHR"><code>LUA_OPSHR</code></a>: </b> performs right shift (<code>>></code>)</li> + +</ul> + + + + +<hr><h3><a name="lua_atpanic"><code>lua_atpanic</code></a></h3><p> +<span class="apii">[-0, +0, –]</span> +<pre>lua_CFunction lua_atpanic (lua_State *L, lua_CFunction panicf);</pre> + +<p> +Sets a new panic function and returns the old one (see <a href="#4.6">§4.6</a>). + + + + + +<hr><h3><a name="lua_call"><code>lua_call</code></a></h3><p> +<span class="apii">[-(nargs+1), +nresults, <em>e</em>]</span> +<pre>void lua_call (lua_State *L, int nargs, int nresults);</pre> + +<p> +Calls a function. + + +<p> +To call a function you must use the following protocol: +first, the function to be called is pushed onto the stack; +then, the arguments to the function are pushed +in direct order; +that is, the first argument is pushed first. +Finally you call <a href="#lua_call"><code>lua_call</code></a>; +<code>nargs</code> is the number of arguments that you pushed onto the stack. +All arguments and the function value are popped from the stack +when the function is called. +The function results are pushed onto the stack when the function returns. +The number of results is adjusted to <code>nresults</code>, +unless <code>nresults</code> is <a name="pdf-LUA_MULTRET"><code>LUA_MULTRET</code></a>. +In this case, all results from the function are pushed; +Lua takes care that the returned values fit into the stack space, +but it does not ensure any extra space in the stack. +The function results are pushed onto the stack in direct order +(the first result is pushed first), +so that after the call the last result is on the top of the stack. + + +<p> +Any error inside the called function is propagated upwards +(with a <code>longjmp</code>). + + +<p> +The following example shows how the host program can do the +equivalent to this Lua code: + +<pre> + a = f("how", t.x, 14) +</pre><p> +Here it is in C: + +<pre> + lua_getglobal(L, "f"); /* function to be called */ + lua_pushliteral(L, "how"); /* 1st argument */ + lua_getglobal(L, "t"); /* table to be indexed */ + lua_getfield(L, -1, "x"); /* push result of t.x (2nd arg) */ + lua_remove(L, -2); /* remove 't' from the stack */ + lua_pushinteger(L, 14); /* 3rd argument */ + lua_call(L, 3, 1); /* call 'f' with 3 arguments and 1 result */ + lua_setglobal(L, "a"); /* set global 'a' */ +</pre><p> +Note that the code above is <em>balanced</em>: +at its end, the stack is back to its original configuration. +This is considered good programming practice. + + + + + +<hr><h3><a name="lua_callk"><code>lua_callk</code></a></h3><p> +<span class="apii">[-(nargs + 1), +nresults, <em>e</em>]</span> +<pre>void lua_callk (lua_State *L, + int nargs, + int nresults, + lua_KContext ctx, + lua_KFunction k);</pre> + +<p> +This function behaves exactly like <a href="#lua_call"><code>lua_call</code></a>, +but allows the called function to yield (see <a href="#4.7">§4.7</a>). + + + + + +<hr><h3><a name="lua_CFunction"><code>lua_CFunction</code></a></h3> +<pre>typedef int (*lua_CFunction) (lua_State *L);</pre> + +<p> +Type for C functions. + + +<p> +In order to communicate properly with Lua, +a C function must use the following protocol, +which defines the way parameters and results are passed: +a C function receives its arguments from Lua in its stack +in direct order (the first argument is pushed first). +So, when the function starts, +<code>lua_gettop(L)</code> returns the number of arguments received by the function. +The first argument (if any) is at index 1 +and its last argument is at index <code>lua_gettop(L)</code>. +To return values to Lua, a C function just pushes them onto the stack, +in direct order (the first result is pushed first), +and returns the number of results. +Any other value in the stack below the results will be properly +discarded by Lua. +Like a Lua function, a C function called by Lua can also return +many results. + + +<p> +As an example, the following function receives a variable number +of numeric arguments and returns their average and their sum: + +<pre> + static int foo (lua_State *L) { + int n = lua_gettop(L); /* number of arguments */ + lua_Number sum = 0.0; + int i; + for (i = 1; i <= n; i++) { + if (!lua_isnumber(L, i)) { + lua_pushliteral(L, "incorrect argument"); + lua_error(L); + } + sum += lua_tonumber(L, i); + } + lua_pushnumber(L, sum/n); /* first result */ + lua_pushnumber(L, sum); /* second result */ + return 2; /* number of results */ + } +</pre> + + + + +<hr><h3><a name="lua_checkstack"><code>lua_checkstack</code></a></h3><p> +<span class="apii">[-0, +0, –]</span> +<pre>int lua_checkstack (lua_State *L, int n);</pre> + +<p> +Ensures that the stack has space for at least <code>n</code> extra slots +(that is, that you can safely push up to <code>n</code> values into it). +It returns false if it cannot fulfill the request, +either because it would cause the stack +to be larger than a fixed maximum size +(typically at least several thousand elements) or +because it cannot allocate memory for the extra space. +This function never shrinks the stack; +if the stack already has space for the extra slots, +it is left unchanged. + + + + + +<hr><h3><a name="lua_close"><code>lua_close</code></a></h3><p> +<span class="apii">[-0, +0, –]</span> +<pre>void lua_close (lua_State *L);</pre> + +<p> +Destroys all objects in the given Lua state +(calling the corresponding garbage-collection metamethods, if any) +and frees all dynamic memory used by this state. +In several platforms, you may not need to call this function, +because all resources are naturally released when the host program ends. +On the other hand, long-running programs that create multiple states, +such as daemons or web servers, +will probably need to close states as soon as they are not needed. + + + + + +<hr><h3><a name="lua_compare"><code>lua_compare</code></a></h3><p> +<span class="apii">[-0, +0, <em>e</em>]</span> +<pre>int lua_compare (lua_State *L, int index1, int index2, int op);</pre> + +<p> +Compares two Lua values. +Returns 1 if the value at index <code>index1</code> satisfies <code>op</code> +when compared with the value at index <code>index2</code>, +following the semantics of the corresponding Lua operator +(that is, it may call metamethods). +Otherwise returns 0. +Also returns 0 if any of the indices is not valid. + + +<p> +The value of <code>op</code> must be one of the following constants: + +<ul> + +<li><b><a name="pdf-LUA_OPEQ"><code>LUA_OPEQ</code></a>: </b> compares for equality (<code>==</code>)</li> +<li><b><a name="pdf-LUA_OPLT"><code>LUA_OPLT</code></a>: </b> compares for less than (<code><</code>)</li> +<li><b><a name="pdf-LUA_OPLE"><code>LUA_OPLE</code></a>: </b> compares for less or equal (<code><=</code>)</li> + +</ul> + + + + +<hr><h3><a name="lua_concat"><code>lua_concat</code></a></h3><p> +<span class="apii">[-n, +1, <em>e</em>]</span> +<pre>void lua_concat (lua_State *L, int n);</pre> + +<p> +Concatenates the <code>n</code> values at the top of the stack, +pops them, and leaves the result at the top. +If <code>n</code> is 1, the result is the single value on the stack +(that is, the function does nothing); +if <code>n</code> is 0, the result is the empty string. +Concatenation is performed following the usual semantics of Lua +(see <a href="#3.4.6">§3.4.6</a>). + + + + + +<hr><h3><a name="lua_copy"><code>lua_copy</code></a></h3><p> +<span class="apii">[-0, +0, –]</span> +<pre>void lua_copy (lua_State *L, int fromidx, int toidx);</pre> + +<p> +Copies the element at index <code>fromidx</code> +into the valid index <code>toidx</code>, +replacing the value at that position. +Values at other positions are not affected. + + + + + +<hr><h3><a name="lua_createtable"><code>lua_createtable</code></a></h3><p> +<span class="apii">[-0, +1, <em>m</em>]</span> +<pre>void lua_createtable (lua_State *L, int narr, int nrec);</pre> + +<p> +Creates a new empty table and pushes it onto the stack. +Parameter <code>narr</code> is a hint for how many elements the table +will have as a sequence; +parameter <code>nrec</code> is a hint for how many other elements +the table will have. +Lua may use these hints to preallocate memory for the new table. +This preallocation is useful for performance when you know in advance +how many elements the table will have. +Otherwise you can use the function <a href="#lua_newtable"><code>lua_newtable</code></a>. + + + + + +<hr><h3><a name="lua_dump"><code>lua_dump</code></a></h3><p> +<span class="apii">[-0, +0, –]</span> +<pre>int lua_dump (lua_State *L, + lua_Writer writer, + void *data, + int strip);</pre> + +<p> +Dumps a function as a binary chunk. +Receives a Lua function on the top of the stack +and produces a binary chunk that, +if loaded again, +results in a function equivalent to the one dumped. +As it produces parts of the chunk, +<a href="#lua_dump"><code>lua_dump</code></a> calls function <code>writer</code> (see <a href="#lua_Writer"><code>lua_Writer</code></a>) +with the given <code>data</code> +to write them. + + +<p> +If <code>strip</code> is true, +the binary representation may not include all debug information +about the function, +to save space. + + +<p> +The value returned is the error code returned by the last +call to the writer; +0 means no errors. + + +<p> +This function does not pop the Lua function from the stack. + + + + + +<hr><h3><a name="lua_error"><code>lua_error</code></a></h3><p> +<span class="apii">[-1, +0, <em>v</em>]</span> +<pre>int lua_error (lua_State *L);</pre> + +<p> +Generates a Lua error, +using the value at the top of the stack as the error object. +This function does a long jump, +and therefore never returns +(see <a href="#luaL_error"><code>luaL_error</code></a>). + + + + + +<hr><h3><a name="lua_gc"><code>lua_gc</code></a></h3><p> +<span class="apii">[-0, +0, <em>m</em>]</span> +<pre>int lua_gc (lua_State *L, int what, int data);</pre> + +<p> +Controls the garbage collector. + + +<p> +This function performs several tasks, +according to the value of the parameter <code>what</code>: + +<ul> + +<li><b><code>LUA_GCSTOP</code>: </b> +stops the garbage collector. +</li> + +<li><b><code>LUA_GCRESTART</code>: </b> +restarts the garbage collector. +</li> + +<li><b><code>LUA_GCCOLLECT</code>: </b> +performs a full garbage-collection cycle. +</li> + +<li><b><code>LUA_GCCOUNT</code>: </b> +returns the current amount of memory (in Kbytes) in use by Lua. +</li> + +<li><b><code>LUA_GCCOUNTB</code>: </b> +returns the remainder of dividing the current amount of bytes of +memory in use by Lua by 1024. +</li> + +<li><b><code>LUA_GCSTEP</code>: </b> +performs an incremental step of garbage collection. +</li> + +<li><b><code>LUA_GCSETPAUSE</code>: </b> +sets <code>data</code> as the new value +for the <em>pause</em> of the collector (see <a href="#2.5">§2.5</a>) +and returns the previous value of the pause. +</li> + +<li><b><code>LUA_GCSETSTEPMUL</code>: </b> +sets <code>data</code> as the new value for the <em>step multiplier</em> of +the collector (see <a href="#2.5">§2.5</a>) +and returns the previous value of the step multiplier. +</li> + +<li><b><code>LUA_GCISRUNNING</code>: </b> +returns a boolean that tells whether the collector is running +(i.e., not stopped). +</li> + +</ul> + +<p> +For more details about these options, +see <a href="#pdf-collectgarbage"><code>collectgarbage</code></a>. + + + + + +<hr><h3><a name="lua_getallocf"><code>lua_getallocf</code></a></h3><p> +<span class="apii">[-0, +0, –]</span> +<pre>lua_Alloc lua_getallocf (lua_State *L, void **ud);</pre> + +<p> +Returns the memory-allocation function of a given state. +If <code>ud</code> is not <code>NULL</code>, Lua stores in <code>*ud</code> the +opaque pointer given when the memory-allocator function was set. + + + + + +<hr><h3><a name="lua_getfield"><code>lua_getfield</code></a></h3><p> +<span class="apii">[-0, +1, <em>e</em>]</span> +<pre>int lua_getfield (lua_State *L, int index, const char *k);</pre> + +<p> +Pushes onto the stack the value <code>t[k]</code>, +where <code>t</code> is the value at the given index. +As in Lua, this function may trigger a metamethod +for the "index" event (see <a href="#2.4">§2.4</a>). + + +<p> +Returns the type of the pushed value. + + + + + +<hr><h3><a name="lua_getextraspace"><code>lua_getextraspace</code></a></h3><p> +<span class="apii">[-0, +0, –]</span> +<pre>void *lua_getextraspace (lua_State *L);</pre> + +<p> +Returns a pointer to a raw memory area associated with the +given Lua state. +The application can use this area for any purpose; +Lua does not use it for anything. + + +<p> +Each new thread has this area initialized with a copy +of the area of the main thread. + + +<p> +By default, this area has the size of a pointer to void, +but you can recompile Lua with a different size for this area. +(See <code>LUA_EXTRASPACE</code> in <code>luaconf.h</code>.) + + + + + +<hr><h3><a name="lua_getglobal"><code>lua_getglobal</code></a></h3><p> +<span class="apii">[-0, +1, <em>e</em>]</span> +<pre>int lua_getglobal (lua_State *L, const char *name);</pre> + +<p> +Pushes onto the stack the value of the global <code>name</code>. +Returns the type of that value. + + + + + +<hr><h3><a name="lua_geti"><code>lua_geti</code></a></h3><p> +<span class="apii">[-0, +1, <em>e</em>]</span> +<pre>int lua_geti (lua_State *L, int index, lua_Integer i);</pre> + +<p> +Pushes onto the stack the value <code>t[i]</code>, +where <code>t</code> is the value at the given index. +As in Lua, this function may trigger a metamethod +for the "index" event (see <a href="#2.4">§2.4</a>). + + +<p> +Returns the type of the pushed value. + + + + + +<hr><h3><a name="lua_getmetatable"><code>lua_getmetatable</code></a></h3><p> +<span class="apii">[-0, +(0|1), –]</span> +<pre>int lua_getmetatable (lua_State *L, int index);</pre> + +<p> +If the value at the given index has a metatable, +the function pushes that metatable onto the stack and returns 1. +Otherwise, +the function returns 0 and pushes nothing on the stack. + + + + + +<hr><h3><a name="lua_gettable"><code>lua_gettable</code></a></h3><p> +<span class="apii">[-1, +1, <em>e</em>]</span> +<pre>int lua_gettable (lua_State *L, int index);</pre> + +<p> +Pushes onto the stack the value <code>t[k]</code>, +where <code>t</code> is the value at the given index +and <code>k</code> is the value at the top of the stack. + + +<p> +This function pops the key from the stack, +pushing the resulting value in its place. +As in Lua, this function may trigger a metamethod +for the "index" event (see <a href="#2.4">§2.4</a>). + + +<p> +Returns the type of the pushed value. + + + + + +<hr><h3><a name="lua_gettop"><code>lua_gettop</code></a></h3><p> +<span class="apii">[-0, +0, –]</span> +<pre>int lua_gettop (lua_State *L);</pre> + +<p> +Returns the index of the top element in the stack. +Because indices start at 1, +this result is equal to the number of elements in the stack; +in particular, 0 means an empty stack. + + + + + +<hr><h3><a name="lua_getuservalue"><code>lua_getuservalue</code></a></h3><p> +<span class="apii">[-0, +1, –]</span> +<pre>int lua_getuservalue (lua_State *L, int index);</pre> + +<p> +Pushes onto the stack the Lua value associated with the full userdata +at the given index. + + +<p> +Returns the type of the pushed value. + + + + + +<hr><h3><a name="lua_insert"><code>lua_insert</code></a></h3><p> +<span class="apii">[-1, +1, –]</span> +<pre>void lua_insert (lua_State *L, int index);</pre> + +<p> +Moves the top element into the given valid index, +shifting up the elements above this index to open space. +This function cannot be called with a pseudo-index, +because a pseudo-index is not an actual stack position. + + + + + +<hr><h3><a name="lua_Integer"><code>lua_Integer</code></a></h3> +<pre>typedef ... lua_Integer;</pre> + +<p> +The type of integers in Lua. + + +<p> +By default this type is <code>long long</code>, +(usually a 64-bit two-complement integer), +but that can be changed to <code>long</code> or <code>int</code> +(usually a 32-bit two-complement integer). +(See <code>LUA_INT_TYPE</code> in <code>luaconf.h</code>.) + + +<p> +Lua also defines the constants +<a name="pdf-LUA_MININTEGER"><code>LUA_MININTEGER</code></a> and <a name="pdf-LUA_MAXINTEGER"><code>LUA_MAXINTEGER</code></a>, +with the minimum and the maximum values that fit in this type. + + + + + +<hr><h3><a name="lua_isboolean"><code>lua_isboolean</code></a></h3><p> +<span class="apii">[-0, +0, –]</span> +<pre>int lua_isboolean (lua_State *L, int index);</pre> + +<p> +Returns 1 if the value at the given index is a boolean, +and 0 otherwise. + + + + + +<hr><h3><a name="lua_iscfunction"><code>lua_iscfunction</code></a></h3><p> +<span class="apii">[-0, +0, –]</span> +<pre>int lua_iscfunction (lua_State *L, int index);</pre> + +<p> +Returns 1 if the value at the given index is a C function, +and 0 otherwise. + + + + + +<hr><h3><a name="lua_isfunction"><code>lua_isfunction</code></a></h3><p> +<span class="apii">[-0, +0, –]</span> +<pre>int lua_isfunction (lua_State *L, int index);</pre> + +<p> +Returns 1 if the value at the given index is a function +(either C or Lua), and 0 otherwise. + + + + + +<hr><h3><a name="lua_isinteger"><code>lua_isinteger</code></a></h3><p> +<span class="apii">[-0, +0, –]</span> +<pre>int lua_isinteger (lua_State *L, int index);</pre> + +<p> +Returns 1 if the value at the given index is an integer +(that is, the value is a number and is represented as an integer), +and 0 otherwise. + + + + + +<hr><h3><a name="lua_islightuserdata"><code>lua_islightuserdata</code></a></h3><p> +<span class="apii">[-0, +0, –]</span> +<pre>int lua_islightuserdata (lua_State *L, int index);</pre> + +<p> +Returns 1 if the value at the given index is a light userdata, +and 0 otherwise. + + + + + +<hr><h3><a name="lua_isnil"><code>lua_isnil</code></a></h3><p> +<span class="apii">[-0, +0, –]</span> +<pre>int lua_isnil (lua_State *L, int index);</pre> + +<p> +Returns 1 if the value at the given index is <b>nil</b>, +and 0 otherwise. + + + + + +<hr><h3><a name="lua_isnone"><code>lua_isnone</code></a></h3><p> +<span class="apii">[-0, +0, –]</span> +<pre>int lua_isnone (lua_State *L, int index);</pre> + +<p> +Returns 1 if the given index is not valid, +and 0 otherwise. + + + + + +<hr><h3><a name="lua_isnoneornil"><code>lua_isnoneornil</code></a></h3><p> +<span class="apii">[-0, +0, –]</span> +<pre>int lua_isnoneornil (lua_State *L, int index);</pre> + +<p> +Returns 1 if the given index is not valid +or if the value at this index is <b>nil</b>, +and 0 otherwise. + + + + + +<hr><h3><a name="lua_isnumber"><code>lua_isnumber</code></a></h3><p> +<span class="apii">[-0, +0, –]</span> +<pre>int lua_isnumber (lua_State *L, int index);</pre> + +<p> +Returns 1 if the value at the given index is a number +or a string convertible to a number, +and 0 otherwise. + + + + + +<hr><h3><a name="lua_isstring"><code>lua_isstring</code></a></h3><p> +<span class="apii">[-0, +0, –]</span> +<pre>int lua_isstring (lua_State *L, int index);</pre> + +<p> +Returns 1 if the value at the given index is a string +or a number (which is always convertible to a string), +and 0 otherwise. + + + + + +<hr><h3><a name="lua_istable"><code>lua_istable</code></a></h3><p> +<span class="apii">[-0, +0, –]</span> +<pre>int lua_istable (lua_State *L, int index);</pre> + +<p> +Returns 1 if the value at the given index is a table, +and 0 otherwise. + + + + + +<hr><h3><a name="lua_isthread"><code>lua_isthread</code></a></h3><p> +<span class="apii">[-0, +0, –]</span> +<pre>int lua_isthread (lua_State *L, int index);</pre> + +<p> +Returns 1 if the value at the given index is a thread, +and 0 otherwise. + + + + + +<hr><h3><a name="lua_isuserdata"><code>lua_isuserdata</code></a></h3><p> +<span class="apii">[-0, +0, –]</span> +<pre>int lua_isuserdata (lua_State *L, int index);</pre> + +<p> +Returns 1 if the value at the given index is a userdata +(either full or light), and 0 otherwise. + + + + + +<hr><h3><a name="lua_isyieldable"><code>lua_isyieldable</code></a></h3><p> +<span class="apii">[-0, +0, –]</span> +<pre>int lua_isyieldable (lua_State *L);</pre> + +<p> +Returns 1 if the given coroutine can yield, +and 0 otherwise. + + + + + +<hr><h3><a name="lua_KContext"><code>lua_KContext</code></a></h3> +<pre>typedef ... lua_KContext;</pre> + +<p> +The type for continuation-function contexts. +It must be a numeric type. +This type is defined as <code>intptr_t</code> +when <code>intptr_t</code> is available, +so that it can store pointers too. +Otherwise, it is defined as <code>ptrdiff_t</code>. + + + + + +<hr><h3><a name="lua_KFunction"><code>lua_KFunction</code></a></h3> +<pre>typedef int (*lua_KFunction) (lua_State *L, int status, lua_KContext ctx);</pre> + +<p> +Type for continuation functions (see <a href="#4.7">§4.7</a>). + + + + + +<hr><h3><a name="lua_len"><code>lua_len</code></a></h3><p> +<span class="apii">[-0, +1, <em>e</em>]</span> +<pre>void lua_len (lua_State *L, int index);</pre> + +<p> +Returns the length of the value at the given index. +It is equivalent to the '<code>#</code>' operator in Lua (see <a href="#3.4.7">§3.4.7</a>) and +may trigger a metamethod for the "length" event (see <a href="#2.4">§2.4</a>). +The result is pushed on the stack. + + + + + +<hr><h3><a name="lua_load"><code>lua_load</code></a></h3><p> +<span class="apii">[-0, +1, –]</span> +<pre>int lua_load (lua_State *L, + lua_Reader reader, + void *data, + const char *chunkname, + const char *mode);</pre> + +<p> +Loads a Lua chunk without running it. +If there are no errors, +<code>lua_load</code> pushes the compiled chunk as a Lua +function on top of the stack. +Otherwise, it pushes an error message. + + +<p> +The return values of <code>lua_load</code> are: + +<ul> + +<li><b><a href="#pdf-LUA_OK"><code>LUA_OK</code></a>: </b> no errors;</li> + +<li><b><a name="pdf-LUA_ERRSYNTAX"><code>LUA_ERRSYNTAX</code></a>: </b> +syntax error during precompilation;</li> + +<li><b><a href="#pdf-LUA_ERRMEM"><code>LUA_ERRMEM</code></a>: </b> +memory allocation (out-of-memory) error;</li> + +<li><b><a href="#pdf-LUA_ERRGCMM"><code>LUA_ERRGCMM</code></a>: </b> +error while running a <code>__gc</code> metamethod. +(This error has no relation with the chunk being loaded. +It is generated by the garbage collector.) +</li> + +</ul> + +<p> +The <code>lua_load</code> function uses a user-supplied <code>reader</code> function +to read the chunk (see <a href="#lua_Reader"><code>lua_Reader</code></a>). +The <code>data</code> argument is an opaque value passed to the reader function. + + +<p> +The <code>chunkname</code> argument gives a name to the chunk, +which is used for error messages and in debug information (see <a href="#4.9">§4.9</a>). + + +<p> +<code>lua_load</code> automatically detects whether the chunk is text or binary +and loads it accordingly (see program <code>luac</code>). +The string <code>mode</code> works as in function <a href="#pdf-load"><code>load</code></a>, +with the addition that +a <code>NULL</code> value is equivalent to the string "<code>bt</code>". + + +<p> +<code>lua_load</code> uses the stack internally, +so the reader function must always leave the stack +unmodified when returning. + + +<p> +If the resulting function has upvalues, +its first upvalue is set to the value of the global environment +stored at index <code>LUA_RIDX_GLOBALS</code> in the registry (see <a href="#4.5">§4.5</a>). +When loading main chunks, +this upvalue will be the <code>_ENV</code> variable (see <a href="#2.2">§2.2</a>). +Other upvalues are initialized with <b>nil</b>. + + + + + +<hr><h3><a name="lua_newstate"><code>lua_newstate</code></a></h3><p> +<span class="apii">[-0, +0, –]</span> +<pre>lua_State *lua_newstate (lua_Alloc f, void *ud);</pre> + +<p> +Creates a new thread running in a new, independent state. +Returns <code>NULL</code> if it cannot create the thread or the state +(due to lack of memory). +The argument <code>f</code> is the allocator function; +Lua does all memory allocation for this state +through this function (see <a href="#lua_Alloc"><code>lua_Alloc</code></a>). +The second argument, <code>ud</code>, is an opaque pointer that Lua +passes to the allocator in every call. + + + + + +<hr><h3><a name="lua_newtable"><code>lua_newtable</code></a></h3><p> +<span class="apii">[-0, +1, <em>m</em>]</span> +<pre>void lua_newtable (lua_State *L);</pre> + +<p> +Creates a new empty table and pushes it onto the stack. +It is equivalent to <code>lua_createtable(L, 0, 0)</code>. + + + + + +<hr><h3><a name="lua_newthread"><code>lua_newthread</code></a></h3><p> +<span class="apii">[-0, +1, <em>m</em>]</span> +<pre>lua_State *lua_newthread (lua_State *L);</pre> + +<p> +Creates a new thread, pushes it on the stack, +and returns a pointer to a <a href="#lua_State"><code>lua_State</code></a> that represents this new thread. +The new thread returned by this function shares with the original thread +its global environment, +but has an independent execution stack. + + +<p> +There is no explicit function to close or to destroy a thread. +Threads are subject to garbage collection, +like any Lua object. + + + + + +<hr><h3><a name="lua_newuserdata"><code>lua_newuserdata</code></a></h3><p> +<span class="apii">[-0, +1, <em>m</em>]</span> +<pre>void *lua_newuserdata (lua_State *L, size_t size);</pre> + +<p> +This function allocates a new block of memory with the given size, +pushes onto the stack a new full userdata with the block address, +and returns this address. +The host program can freely use this memory. + + + + + +<hr><h3><a name="lua_next"><code>lua_next</code></a></h3><p> +<span class="apii">[-1, +(2|0), <em>e</em>]</span> +<pre>int lua_next (lua_State *L, int index);</pre> + +<p> +Pops a key from the stack, +and pushes a key–value pair from the table at the given index +(the "next" pair after the given key). +If there are no more elements in the table, +then <a href="#lua_next"><code>lua_next</code></a> returns 0 (and pushes nothing). + + +<p> +A typical traversal looks like this: + +<pre> + /* table is in the stack at index 't' */ + lua_pushnil(L); /* first key */ + while (lua_next(L, t) != 0) { + /* uses 'key' (at index -2) and 'value' (at index -1) */ + printf("%s - %s\n", + lua_typename(L, lua_type(L, -2)), + lua_typename(L, lua_type(L, -1))); + /* removes 'value'; keeps 'key' for next iteration */ + lua_pop(L, 1); + } +</pre> + +<p> +While traversing a table, +do not call <a href="#lua_tolstring"><code>lua_tolstring</code></a> directly on a key, +unless you know that the key is actually a string. +Recall that <a href="#lua_tolstring"><code>lua_tolstring</code></a> may change +the value at the given index; +this confuses the next call to <a href="#lua_next"><code>lua_next</code></a>. + + +<p> +See function <a href="#pdf-next"><code>next</code></a> for the caveats of modifying +the table during its traversal. + + + + + +<hr><h3><a name="lua_Number"><code>lua_Number</code></a></h3> +<pre>typedef ... lua_Number;</pre> + +<p> +The type of floats in Lua. + + +<p> +By default this type is double, +but that can be changed to a single float or a long double. +(See <code>LUA_FLOAT_TYPE</code> in <code>luaconf.h</code>.) + + + + + +<hr><h3><a name="lua_numbertointeger"><code>lua_numbertointeger</code></a></h3> +<pre>int lua_numbertointeger (lua_Number n, lua_Integer *p);</pre> + +<p> +Converts a Lua float to a Lua integer. +This macro assumes that <code>n</code> has an integral value. +If that value is within the range of Lua integers, +it is converted to an integer and assigned to <code>*p</code>. +The macro results in a boolean indicating whether the +conversion was successful. +(Note that this range test can be tricky to do +correctly without this macro, +due to roundings.) + + +<p> +This macro may evaluate its arguments more than once. + + + + + +<hr><h3><a name="lua_pcall"><code>lua_pcall</code></a></h3><p> +<span class="apii">[-(nargs + 1), +(nresults|1), –]</span> +<pre>int lua_pcall (lua_State *L, int nargs, int nresults, int msgh);</pre> + +<p> +Calls a function in protected mode. + + +<p> +Both <code>nargs</code> and <code>nresults</code> have the same meaning as +in <a href="#lua_call"><code>lua_call</code></a>. +If there are no errors during the call, +<a href="#lua_pcall"><code>lua_pcall</code></a> behaves exactly like <a href="#lua_call"><code>lua_call</code></a>. +However, if there is any error, +<a href="#lua_pcall"><code>lua_pcall</code></a> catches it, +pushes a single value on the stack (the error object), +and returns an error code. +Like <a href="#lua_call"><code>lua_call</code></a>, +<a href="#lua_pcall"><code>lua_pcall</code></a> always removes the function +and its arguments from the stack. + + +<p> +If <code>msgh</code> is 0, +then the error object returned on the stack +is exactly the original error object. +Otherwise, <code>msgh</code> is the stack index of a +<em>message handler</em>. +(This index cannot be a pseudo-index.) +In case of runtime errors, +this function will be called with the error object +and its return value will be the object +returned on the stack by <a href="#lua_pcall"><code>lua_pcall</code></a>. + + +<p> +Typically, the message handler is used to add more debug +information to the error object, such as a stack traceback. +Such information cannot be gathered after the return of <a href="#lua_pcall"><code>lua_pcall</code></a>, +since by then the stack has unwound. + + +<p> +The <a href="#lua_pcall"><code>lua_pcall</code></a> function returns one of the following constants +(defined in <code>lua.h</code>): + +<ul> + +<li><b><a name="pdf-LUA_OK"><code>LUA_OK</code></a> (0): </b> +success.</li> + +<li><b><a name="pdf-LUA_ERRRUN"><code>LUA_ERRRUN</code></a>: </b> +a runtime error. +</li> + +<li><b><a name="pdf-LUA_ERRMEM"><code>LUA_ERRMEM</code></a>: </b> +memory allocation error. +For such errors, Lua does not call the message handler. +</li> + +<li><b><a name="pdf-LUA_ERRERR"><code>LUA_ERRERR</code></a>: </b> +error while running the message handler. +</li> + +<li><b><a name="pdf-LUA_ERRGCMM"><code>LUA_ERRGCMM</code></a>: </b> +error while running a <code>__gc</code> metamethod. +For such errors, Lua does not call the message handler +(as this kind of error typically has no relation +with the function being called). +</li> + +</ul> + + + + +<hr><h3><a name="lua_pcallk"><code>lua_pcallk</code></a></h3><p> +<span class="apii">[-(nargs + 1), +(nresults|1), –]</span> +<pre>int lua_pcallk (lua_State *L, + int nargs, + int nresults, + int msgh, + lua_KContext ctx, + lua_KFunction k);</pre> + +<p> +This function behaves exactly like <a href="#lua_pcall"><code>lua_pcall</code></a>, +but allows the called function to yield (see <a href="#4.7">§4.7</a>). + + + + + +<hr><h3><a name="lua_pop"><code>lua_pop</code></a></h3><p> +<span class="apii">[-n, +0, –]</span> +<pre>void lua_pop (lua_State *L, int n);</pre> + +<p> +Pops <code>n</code> elements from the stack. + + + + + +<hr><h3><a name="lua_pushboolean"><code>lua_pushboolean</code></a></h3><p> +<span class="apii">[-0, +1, –]</span> +<pre>void lua_pushboolean (lua_State *L, int b);</pre> + +<p> +Pushes a boolean value with value <code>b</code> onto the stack. + + + + + +<hr><h3><a name="lua_pushcclosure"><code>lua_pushcclosure</code></a></h3><p> +<span class="apii">[-n, +1, <em>m</em>]</span> +<pre>void lua_pushcclosure (lua_State *L, lua_CFunction fn, int n);</pre> + +<p> +Pushes a new C closure onto the stack. + + +<p> +When a C function is created, +it is possible to associate some values with it, +thus creating a C closure (see <a href="#4.4">§4.4</a>); +these values are then accessible to the function whenever it is called. +To associate values with a C function, +first these values must be pushed onto the stack +(when there are multiple values, the first value is pushed first). +Then <a href="#lua_pushcclosure"><code>lua_pushcclosure</code></a> +is called to create and push the C function onto the stack, +with the argument <code>n</code> telling how many values will be +associated with the function. +<a href="#lua_pushcclosure"><code>lua_pushcclosure</code></a> also pops these values from the stack. + + +<p> +The maximum value for <code>n</code> is 255. + + +<p> +When <code>n</code> is zero, +this function creates a <em>light C function</em>, +which is just a pointer to the C function. +In that case, it never raises a memory error. + + + + + +<hr><h3><a name="lua_pushcfunction"><code>lua_pushcfunction</code></a></h3><p> +<span class="apii">[-0, +1, –]</span> +<pre>void lua_pushcfunction (lua_State *L, lua_CFunction f);</pre> + +<p> +Pushes a C function onto the stack. +This function receives a pointer to a C function +and pushes onto the stack a Lua value of type <code>function</code> that, +when called, invokes the corresponding C function. + + +<p> +Any function to be callable by Lua must +follow the correct protocol to receive its parameters +and return its results (see <a href="#lua_CFunction"><code>lua_CFunction</code></a>). + + + + + +<hr><h3><a name="lua_pushfstring"><code>lua_pushfstring</code></a></h3><p> +<span class="apii">[-0, +1, <em>e</em>]</span> +<pre>const char *lua_pushfstring (lua_State *L, const char *fmt, ...);</pre> + +<p> +Pushes onto the stack a formatted string +and returns a pointer to this string. +It is similar to the ISO C function <code>sprintf</code>, +but has some important differences: + +<ul> + +<li> +You do not have to allocate space for the result: +the result is a Lua string and Lua takes care of memory allocation +(and deallocation, through garbage collection). +</li> + +<li> +The conversion specifiers are quite restricted. +There are no flags, widths, or precisions. +The conversion specifiers can only be +'<code>%%</code>' (inserts the character '<code>%</code>'), +'<code>%s</code>' (inserts a zero-terminated string, with no size restrictions), +'<code>%f</code>' (inserts a <a href="#lua_Number"><code>lua_Number</code></a>), +'<code>%I</code>' (inserts a <a href="#lua_Integer"><code>lua_Integer</code></a>), +'<code>%p</code>' (inserts a pointer as a hexadecimal numeral), +'<code>%d</code>' (inserts an <code>int</code>), +'<code>%c</code>' (inserts an <code>int</code> as a one-byte character), and +'<code>%U</code>' (inserts a <code>long int</code> as a UTF-8 byte sequence). +</li> + +</ul> + +<p> +Unlike other push functions, +this function checks for the stack space it needs, +including the slot for its result. + + + + + +<hr><h3><a name="lua_pushglobaltable"><code>lua_pushglobaltable</code></a></h3><p> +<span class="apii">[-0, +1, –]</span> +<pre>void lua_pushglobaltable (lua_State *L);</pre> + +<p> +Pushes the global environment onto the stack. + + + + + +<hr><h3><a name="lua_pushinteger"><code>lua_pushinteger</code></a></h3><p> +<span class="apii">[-0, +1, –]</span> +<pre>void lua_pushinteger (lua_State *L, lua_Integer n);</pre> + +<p> +Pushes an integer with value <code>n</code> onto the stack. + + + + + +<hr><h3><a name="lua_pushlightuserdata"><code>lua_pushlightuserdata</code></a></h3><p> +<span class="apii">[-0, +1, –]</span> +<pre>void lua_pushlightuserdata (lua_State *L, void *p);</pre> + +<p> +Pushes a light userdata onto the stack. + + +<p> +Userdata represent C values in Lua. +A <em>light userdata</em> represents a pointer, a <code>void*</code>. +It is a value (like a number): +you do not create it, it has no individual metatable, +and it is not collected (as it was never created). +A light userdata is equal to "any" +light userdata with the same C address. + + + + + +<hr><h3><a name="lua_pushliteral"><code>lua_pushliteral</code></a></h3><p> +<span class="apii">[-0, +1, <em>m</em>]</span> +<pre>const char *lua_pushliteral (lua_State *L, const char *s);</pre> + +<p> +This macro is equivalent to <a href="#lua_pushstring"><code>lua_pushstring</code></a>, +but should be used only when <code>s</code> is a literal string. + + + + + +<hr><h3><a name="lua_pushlstring"><code>lua_pushlstring</code></a></h3><p> +<span class="apii">[-0, +1, <em>m</em>]</span> +<pre>const char *lua_pushlstring (lua_State *L, const char *s, size_t len);</pre> + +<p> +Pushes the string pointed to by <code>s</code> with size <code>len</code> +onto the stack. +Lua makes (or reuses) an internal copy of the given string, +so the memory at <code>s</code> can be freed or reused immediately after +the function returns. +The string can contain any binary data, +including embedded zeros. + + +<p> +Returns a pointer to the internal copy of the string. + + + + + +<hr><h3><a name="lua_pushnil"><code>lua_pushnil</code></a></h3><p> +<span class="apii">[-0, +1, –]</span> +<pre>void lua_pushnil (lua_State *L);</pre> + +<p> +Pushes a nil value onto the stack. + + + + + +<hr><h3><a name="lua_pushnumber"><code>lua_pushnumber</code></a></h3><p> +<span class="apii">[-0, +1, –]</span> +<pre>void lua_pushnumber (lua_State *L, lua_Number n);</pre> + +<p> +Pushes a float with value <code>n</code> onto the stack. + + + + + +<hr><h3><a name="lua_pushstring"><code>lua_pushstring</code></a></h3><p> +<span class="apii">[-0, +1, <em>m</em>]</span> +<pre>const char *lua_pushstring (lua_State *L, const char *s);</pre> + +<p> +Pushes the zero-terminated string pointed to by <code>s</code> +onto the stack. +Lua makes (or reuses) an internal copy of the given string, +so the memory at <code>s</code> can be freed or reused immediately after +the function returns. + + +<p> +Returns a pointer to the internal copy of the string. + + +<p> +If <code>s</code> is <code>NULL</code>, pushes <b>nil</b> and returns <code>NULL</code>. + + + + + +<hr><h3><a name="lua_pushthread"><code>lua_pushthread</code></a></h3><p> +<span class="apii">[-0, +1, –]</span> +<pre>int lua_pushthread (lua_State *L);</pre> + +<p> +Pushes the thread represented by <code>L</code> onto the stack. +Returns 1 if this thread is the main thread of its state. + + + + + +<hr><h3><a name="lua_pushvalue"><code>lua_pushvalue</code></a></h3><p> +<span class="apii">[-0, +1, –]</span> +<pre>void lua_pushvalue (lua_State *L, int index);</pre> + +<p> +Pushes a copy of the element at the given index +onto the stack. + + + + + +<hr><h3><a name="lua_pushvfstring"><code>lua_pushvfstring</code></a></h3><p> +<span class="apii">[-0, +1, <em>m</em>]</span> +<pre>const char *lua_pushvfstring (lua_State *L, + const char *fmt, + va_list argp);</pre> + +<p> +Equivalent to <a href="#lua_pushfstring"><code>lua_pushfstring</code></a>, except that it receives a <code>va_list</code> +instead of a variable number of arguments. + + + + + +<hr><h3><a name="lua_rawequal"><code>lua_rawequal</code></a></h3><p> +<span class="apii">[-0, +0, –]</span> +<pre>int lua_rawequal (lua_State *L, int index1, int index2);</pre> + +<p> +Returns 1 if the two values in indices <code>index1</code> and +<code>index2</code> are primitively equal +(that is, without calling the <code>__eq</code> metamethod). +Otherwise returns 0. +Also returns 0 if any of the indices are not valid. + + + + + +<hr><h3><a name="lua_rawget"><code>lua_rawget</code></a></h3><p> +<span class="apii">[-1, +1, –]</span> +<pre>int lua_rawget (lua_State *L, int index);</pre> + +<p> +Similar to <a href="#lua_gettable"><code>lua_gettable</code></a>, but does a raw access +(i.e., without metamethods). + + + + + +<hr><h3><a name="lua_rawgeti"><code>lua_rawgeti</code></a></h3><p> +<span class="apii">[-0, +1, –]</span> +<pre>int lua_rawgeti (lua_State *L, int index, lua_Integer n);</pre> + +<p> +Pushes onto the stack the value <code>t[n]</code>, +where <code>t</code> is the table at the given index. +The access is raw, +that is, it does not invoke the <code>__index</code> metamethod. + + +<p> +Returns the type of the pushed value. + + + + + +<hr><h3><a name="lua_rawgetp"><code>lua_rawgetp</code></a></h3><p> +<span class="apii">[-0, +1, –]</span> +<pre>int lua_rawgetp (lua_State *L, int index, const void *p);</pre> + +<p> +Pushes onto the stack the value <code>t[k]</code>, +where <code>t</code> is the table at the given index and +<code>k</code> is the pointer <code>p</code> represented as a light userdata. +The access is raw; +that is, it does not invoke the <code>__index</code> metamethod. + + +<p> +Returns the type of the pushed value. + + + + + +<hr><h3><a name="lua_rawlen"><code>lua_rawlen</code></a></h3><p> +<span class="apii">[-0, +0, –]</span> +<pre>size_t lua_rawlen (lua_State *L, int index);</pre> + +<p> +Returns the raw "length" of the value at the given index: +for strings, this is the string length; +for tables, this is the result of the length operator ('<code>#</code>') +with no metamethods; +for userdata, this is the size of the block of memory allocated +for the userdata; +for other values, it is 0. + + + + + +<hr><h3><a name="lua_rawset"><code>lua_rawset</code></a></h3><p> +<span class="apii">[-2, +0, <em>m</em>]</span> +<pre>void lua_rawset (lua_State *L, int index);</pre> + +<p> +Similar to <a href="#lua_settable"><code>lua_settable</code></a>, but does a raw assignment +(i.e., without metamethods). + + + + + +<hr><h3><a name="lua_rawseti"><code>lua_rawseti</code></a></h3><p> +<span class="apii">[-1, +0, <em>m</em>]</span> +<pre>void lua_rawseti (lua_State *L, int index, lua_Integer i);</pre> + +<p> +Does the equivalent of <code>t[i] = v</code>, +where <code>t</code> is the table at the given index +and <code>v</code> is the value at the top of the stack. + + +<p> +This function pops the value from the stack. +The assignment is raw, +that is, it does not invoke the <code>__newindex</code> metamethod. + + + + + +<hr><h3><a name="lua_rawsetp"><code>lua_rawsetp</code></a></h3><p> +<span class="apii">[-1, +0, <em>m</em>]</span> +<pre>void lua_rawsetp (lua_State *L, int index, const void *p);</pre> + +<p> +Does the equivalent of <code>t[p] = v</code>, +where <code>t</code> is the table at the given index, +<code>p</code> is encoded as a light userdata, +and <code>v</code> is the value at the top of the stack. + + +<p> +This function pops the value from the stack. +The assignment is raw, +that is, it does not invoke <code>__newindex</code> metamethod. + + + + + +<hr><h3><a name="lua_Reader"><code>lua_Reader</code></a></h3> +<pre>typedef const char * (*lua_Reader) (lua_State *L, + void *data, + size_t *size);</pre> + +<p> +The reader function used by <a href="#lua_load"><code>lua_load</code></a>. +Every time it needs another piece of the chunk, +<a href="#lua_load"><code>lua_load</code></a> calls the reader, +passing along its <code>data</code> parameter. +The reader must return a pointer to a block of memory +with a new piece of the chunk +and set <code>size</code> to the block size. +The block must exist until the reader function is called again. +To signal the end of the chunk, +the reader must return <code>NULL</code> or set <code>size</code> to zero. +The reader function may return pieces of any size greater than zero. + + + + + +<hr><h3><a name="lua_register"><code>lua_register</code></a></h3><p> +<span class="apii">[-0, +0, <em>e</em>]</span> +<pre>void lua_register (lua_State *L, const char *name, lua_CFunction f);</pre> + +<p> +Sets the C function <code>f</code> as the new value of global <code>name</code>. +It is defined as a macro: + +<pre> + #define lua_register(L,n,f) \ + (lua_pushcfunction(L, f), lua_setglobal(L, n)) +</pre> + + + + +<hr><h3><a name="lua_remove"><code>lua_remove</code></a></h3><p> +<span class="apii">[-1, +0, –]</span> +<pre>void lua_remove (lua_State *L, int index);</pre> + +<p> +Removes the element at the given valid index, +shifting down the elements above this index to fill the gap. +This function cannot be called with a pseudo-index, +because a pseudo-index is not an actual stack position. + + + + + +<hr><h3><a name="lua_replace"><code>lua_replace</code></a></h3><p> +<span class="apii">[-1, +0, –]</span> +<pre>void lua_replace (lua_State *L, int index);</pre> + +<p> +Moves the top element into the given valid index +without shifting any element +(therefore replacing the value at that given index), +and then pops the top element. + + + + + +<hr><h3><a name="lua_resume"><code>lua_resume</code></a></h3><p> +<span class="apii">[-?, +?, –]</span> +<pre>int lua_resume (lua_State *L, lua_State *from, int nargs);</pre> + +<p> +Starts and resumes a coroutine in the given thread <code>L</code>. + + +<p> +To start a coroutine, +you push onto the thread stack the main function plus any arguments; +then you call <a href="#lua_resume"><code>lua_resume</code></a>, +with <code>nargs</code> being the number of arguments. +This call returns when the coroutine suspends or finishes its execution. +When it returns, the stack contains all values passed to <a href="#lua_yield"><code>lua_yield</code></a>, +or all values returned by the body function. +<a href="#lua_resume"><code>lua_resume</code></a> returns +<a href="#pdf-LUA_YIELD"><code>LUA_YIELD</code></a> if the coroutine yields, +<a href="#pdf-LUA_OK"><code>LUA_OK</code></a> if the coroutine finishes its execution +without errors, +or an error code in case of errors (see <a href="#lua_pcall"><code>lua_pcall</code></a>). + + +<p> +In case of errors, +the stack is not unwound, +so you can use the debug API over it. +The error object is on the top of the stack. + + +<p> +To resume a coroutine, +you remove any results from the last <a href="#lua_yield"><code>lua_yield</code></a>, +put on its stack only the values to +be passed as results from <code>yield</code>, +and then call <a href="#lua_resume"><code>lua_resume</code></a>. + + +<p> +The parameter <code>from</code> represents the coroutine that is resuming <code>L</code>. +If there is no such coroutine, +this parameter can be <code>NULL</code>. + + + + + +<hr><h3><a name="lua_rotate"><code>lua_rotate</code></a></h3><p> +<span class="apii">[-0, +0, –]</span> +<pre>void lua_rotate (lua_State *L, int idx, int n);</pre> + +<p> +Rotates the stack elements between the valid index <code>idx</code> +and the top of the stack. +The elements are rotated <code>n</code> positions in the direction of the top, +for a positive <code>n</code>, +or <code>-n</code> positions in the direction of the bottom, +for a negative <code>n</code>. +The absolute value of <code>n</code> must not be greater than the size +of the slice being rotated. +This function cannot be called with a pseudo-index, +because a pseudo-index is not an actual stack position. + + + + + +<hr><h3><a name="lua_setallocf"><code>lua_setallocf</code></a></h3><p> +<span class="apii">[-0, +0, –]</span> +<pre>void lua_setallocf (lua_State *L, lua_Alloc f, void *ud);</pre> + +<p> +Changes the allocator function of a given state to <code>f</code> +with user data <code>ud</code>. + + + + + +<hr><h3><a name="lua_setfield"><code>lua_setfield</code></a></h3><p> +<span class="apii">[-1, +0, <em>e</em>]</span> +<pre>void lua_setfield (lua_State *L, int index, const char *k);</pre> + +<p> +Does the equivalent to <code>t[k] = v</code>, +where <code>t</code> is the value at the given index +and <code>v</code> is the value at the top of the stack. + + +<p> +This function pops the value from the stack. +As in Lua, this function may trigger a metamethod +for the "newindex" event (see <a href="#2.4">§2.4</a>). + + + + + +<hr><h3><a name="lua_setglobal"><code>lua_setglobal</code></a></h3><p> +<span class="apii">[-1, +0, <em>e</em>]</span> +<pre>void lua_setglobal (lua_State *L, const char *name);</pre> + +<p> +Pops a value from the stack and +sets it as the new value of global <code>name</code>. + + + + + +<hr><h3><a name="lua_seti"><code>lua_seti</code></a></h3><p> +<span class="apii">[-1, +0, <em>e</em>]</span> +<pre>void lua_seti (lua_State *L, int index, lua_Integer n);</pre> + +<p> +Does the equivalent to <code>t[n] = v</code>, +where <code>t</code> is the value at the given index +and <code>v</code> is the value at the top of the stack. + + +<p> +This function pops the value from the stack. +As in Lua, this function may trigger a metamethod +for the "newindex" event (see <a href="#2.4">§2.4</a>). + + + + + +<hr><h3><a name="lua_setmetatable"><code>lua_setmetatable</code></a></h3><p> +<span class="apii">[-1, +0, –]</span> +<pre>void lua_setmetatable (lua_State *L, int index);</pre> + +<p> +Pops a table from the stack and +sets it as the new metatable for the value at the given index. + + + + + +<hr><h3><a name="lua_settable"><code>lua_settable</code></a></h3><p> +<span class="apii">[-2, +0, <em>e</em>]</span> +<pre>void lua_settable (lua_State *L, int index);</pre> + +<p> +Does the equivalent to <code>t[k] = v</code>, +where <code>t</code> is the value at the given index, +<code>v</code> is the value at the top of the stack, +and <code>k</code> is the value just below the top. + + +<p> +This function pops both the key and the value from the stack. +As in Lua, this function may trigger a metamethod +for the "newindex" event (see <a href="#2.4">§2.4</a>). + + + + + +<hr><h3><a name="lua_settop"><code>lua_settop</code></a></h3><p> +<span class="apii">[-?, +?, –]</span> +<pre>void lua_settop (lua_State *L, int index);</pre> + +<p> +Accepts any index, or 0, +and sets the stack top to this index. +If the new top is larger than the old one, +then the new elements are filled with <b>nil</b>. +If <code>index</code> is 0, then all stack elements are removed. + + + + + +<hr><h3><a name="lua_setuservalue"><code>lua_setuservalue</code></a></h3><p> +<span class="apii">[-1, +0, –]</span> +<pre>void lua_setuservalue (lua_State *L, int index);</pre> + +<p> +Pops a value from the stack and sets it as +the new value associated to the full userdata at the given index. + + + + + +<hr><h3><a name="lua_State"><code>lua_State</code></a></h3> +<pre>typedef struct lua_State lua_State;</pre> + +<p> +An opaque structure that points to a thread and indirectly +(through the thread) to the whole state of a Lua interpreter. +The Lua library is fully reentrant: +it has no global variables. +All information about a state is accessible through this structure. + + +<p> +A pointer to this structure must be passed as the first argument to +every function in the library, except to <a href="#lua_newstate"><code>lua_newstate</code></a>, +which creates a Lua state from scratch. + + + + + +<hr><h3><a name="lua_status"><code>lua_status</code></a></h3><p> +<span class="apii">[-0, +0, –]</span> +<pre>int lua_status (lua_State *L);</pre> + +<p> +Returns the status of the thread <code>L</code>. + + +<p> +The status can be 0 (<a href="#pdf-LUA_OK"><code>LUA_OK</code></a>) for a normal thread, +an error code if the thread finished the execution +of a <a href="#lua_resume"><code>lua_resume</code></a> with an error, +or <a name="pdf-LUA_YIELD"><code>LUA_YIELD</code></a> if the thread is suspended. + + +<p> +You can only call functions in threads with status <a href="#pdf-LUA_OK"><code>LUA_OK</code></a>. +You can resume threads with status <a href="#pdf-LUA_OK"><code>LUA_OK</code></a> +(to start a new coroutine) or <a href="#pdf-LUA_YIELD"><code>LUA_YIELD</code></a> +(to resume a coroutine). + + + + + +<hr><h3><a name="lua_stringtonumber"><code>lua_stringtonumber</code></a></h3><p> +<span class="apii">[-0, +1, –]</span> +<pre>size_t lua_stringtonumber (lua_State *L, const char *s);</pre> + +<p> +Converts the zero-terminated string <code>s</code> to a number, +pushes that number into the stack, +and returns the total size of the string, +that is, its length plus one. +The conversion can result in an integer or a float, +according to the lexical conventions of Lua (see <a href="#3.1">§3.1</a>). +The string may have leading and trailing spaces and a sign. +If the string is not a valid numeral, +returns 0 and pushes nothing. +(Note that the result can be used as a boolean, +true if the conversion succeeds.) + + + + + +<hr><h3><a name="lua_toboolean"><code>lua_toboolean</code></a></h3><p> +<span class="apii">[-0, +0, –]</span> +<pre>int lua_toboolean (lua_State *L, int index);</pre> + +<p> +Converts the Lua value at the given index to a C boolean +value (0 or 1). +Like all tests in Lua, +<a href="#lua_toboolean"><code>lua_toboolean</code></a> returns true for any Lua value +different from <b>false</b> and <b>nil</b>; +otherwise it returns false. +(If you want to accept only actual boolean values, +use <a href="#lua_isboolean"><code>lua_isboolean</code></a> to test the value's type.) + + + + + +<hr><h3><a name="lua_tocfunction"><code>lua_tocfunction</code></a></h3><p> +<span class="apii">[-0, +0, –]</span> +<pre>lua_CFunction lua_tocfunction (lua_State *L, int index);</pre> + +<p> +Converts a value at the given index to a C function. +That value must be a C function; +otherwise, returns <code>NULL</code>. + + + + + +<hr><h3><a name="lua_tointeger"><code>lua_tointeger</code></a></h3><p> +<span class="apii">[-0, +0, –]</span> +<pre>lua_Integer lua_tointeger (lua_State *L, int index);</pre> + +<p> +Equivalent to <a href="#lua_tointegerx"><code>lua_tointegerx</code></a> with <code>isnum</code> equal to <code>NULL</code>. + + + + + +<hr><h3><a name="lua_tointegerx"><code>lua_tointegerx</code></a></h3><p> +<span class="apii">[-0, +0, –]</span> +<pre>lua_Integer lua_tointegerx (lua_State *L, int index, int *isnum);</pre> + +<p> +Converts the Lua value at the given index +to the signed integral type <a href="#lua_Integer"><code>lua_Integer</code></a>. +The Lua value must be an integer, +or a number or string convertible to an integer (see <a href="#3.4.3">§3.4.3</a>); +otherwise, <code>lua_tointegerx</code> returns 0. + + +<p> +If <code>isnum</code> is not <code>NULL</code>, +its referent is assigned a boolean value that +indicates whether the operation succeeded. + + + + + +<hr><h3><a name="lua_tolstring"><code>lua_tolstring</code></a></h3><p> +<span class="apii">[-0, +0, <em>m</em>]</span> +<pre>const char *lua_tolstring (lua_State *L, int index, size_t *len);</pre> + +<p> +Converts the Lua value at the given index to a C string. +If <code>len</code> is not <code>NULL</code>, +it sets <code>*len</code> with the string length. +The Lua value must be a string or a number; +otherwise, the function returns <code>NULL</code>. +If the value is a number, +then <code>lua_tolstring</code> also +<em>changes the actual value in the stack to a string</em>. +(This change confuses <a href="#lua_next"><code>lua_next</code></a> +when <code>lua_tolstring</code> is applied to keys during a table traversal.) + + +<p> +<code>lua_tolstring</code> returns a pointer +to a string inside the Lua state. +This string always has a zero ('<code>\0</code>') +after its last character (as in C), +but can contain other zeros in its body. + + +<p> +Because Lua has garbage collection, +there is no guarantee that the pointer returned by <code>lua_tolstring</code> +will be valid after the corresponding Lua value is removed from the stack. + + + + + +<hr><h3><a name="lua_tonumber"><code>lua_tonumber</code></a></h3><p> +<span class="apii">[-0, +0, –]</span> +<pre>lua_Number lua_tonumber (lua_State *L, int index);</pre> + +<p> +Equivalent to <a href="#lua_tonumberx"><code>lua_tonumberx</code></a> with <code>isnum</code> equal to <code>NULL</code>. + + + + + +<hr><h3><a name="lua_tonumberx"><code>lua_tonumberx</code></a></h3><p> +<span class="apii">[-0, +0, –]</span> +<pre>lua_Number lua_tonumberx (lua_State *L, int index, int *isnum);</pre> + +<p> +Converts the Lua value at the given index +to the C type <a href="#lua_Number"><code>lua_Number</code></a> (see <a href="#lua_Number"><code>lua_Number</code></a>). +The Lua value must be a number or a string convertible to a number +(see <a href="#3.4.3">§3.4.3</a>); +otherwise, <a href="#lua_tonumberx"><code>lua_tonumberx</code></a> returns 0. + + +<p> +If <code>isnum</code> is not <code>NULL</code>, +its referent is assigned a boolean value that +indicates whether the operation succeeded. + + + + + +<hr><h3><a name="lua_topointer"><code>lua_topointer</code></a></h3><p> +<span class="apii">[-0, +0, –]</span> +<pre>const void *lua_topointer (lua_State *L, int index);</pre> + +<p> +Converts the value at the given index to a generic +C pointer (<code>void*</code>). +The value can be a userdata, a table, a thread, or a function; +otherwise, <code>lua_topointer</code> returns <code>NULL</code>. +Different objects will give different pointers. +There is no way to convert the pointer back to its original value. + + +<p> +Typically this function is used only for hashing and debug information. + + + + + +<hr><h3><a name="lua_tostring"><code>lua_tostring</code></a></h3><p> +<span class="apii">[-0, +0, <em>m</em>]</span> +<pre>const char *lua_tostring (lua_State *L, int index);</pre> + +<p> +Equivalent to <a href="#lua_tolstring"><code>lua_tolstring</code></a> with <code>len</code> equal to <code>NULL</code>. + + + + + +<hr><h3><a name="lua_tothread"><code>lua_tothread</code></a></h3><p> +<span class="apii">[-0, +0, –]</span> +<pre>lua_State *lua_tothread (lua_State *L, int index);</pre> + +<p> +Converts the value at the given index to a Lua thread +(represented as <code>lua_State*</code>). +This value must be a thread; +otherwise, the function returns <code>NULL</code>. + + + + + +<hr><h3><a name="lua_touserdata"><code>lua_touserdata</code></a></h3><p> +<span class="apii">[-0, +0, –]</span> +<pre>void *lua_touserdata (lua_State *L, int index);</pre> + +<p> +If the value at the given index is a full userdata, +returns its block address. +If the value is a light userdata, +returns its pointer. +Otherwise, returns <code>NULL</code>. + + + + + +<hr><h3><a name="lua_type"><code>lua_type</code></a></h3><p> +<span class="apii">[-0, +0, –]</span> +<pre>int lua_type (lua_State *L, int index);</pre> + +<p> +Returns the type of the value in the given valid index, +or <code>LUA_TNONE</code> for a non-valid (but acceptable) index. +The types returned by <a href="#lua_type"><code>lua_type</code></a> are coded by the following constants +defined in <code>lua.h</code>: +<a name="pdf-LUA_TNIL"><code>LUA_TNIL</code></a> (0), +<a name="pdf-LUA_TNUMBER"><code>LUA_TNUMBER</code></a>, +<a name="pdf-LUA_TBOOLEAN"><code>LUA_TBOOLEAN</code></a>, +<a name="pdf-LUA_TSTRING"><code>LUA_TSTRING</code></a>, +<a name="pdf-LUA_TTABLE"><code>LUA_TTABLE</code></a>, +<a name="pdf-LUA_TFUNCTION"><code>LUA_TFUNCTION</code></a>, +<a name="pdf-LUA_TUSERDATA"><code>LUA_TUSERDATA</code></a>, +<a name="pdf-LUA_TTHREAD"><code>LUA_TTHREAD</code></a>, +and +<a name="pdf-LUA_TLIGHTUSERDATA"><code>LUA_TLIGHTUSERDATA</code></a>. + + + + + +<hr><h3><a name="lua_typename"><code>lua_typename</code></a></h3><p> +<span class="apii">[-0, +0, –]</span> +<pre>const char *lua_typename (lua_State *L, int tp);</pre> + +<p> +Returns the name of the type encoded by the value <code>tp</code>, +which must be one the values returned by <a href="#lua_type"><code>lua_type</code></a>. + + + + + +<hr><h3><a name="lua_Unsigned"><code>lua_Unsigned</code></a></h3> +<pre>typedef ... lua_Unsigned;</pre> + +<p> +The unsigned version of <a href="#lua_Integer"><code>lua_Integer</code></a>. + + + + + +<hr><h3><a name="lua_upvalueindex"><code>lua_upvalueindex</code></a></h3><p> +<span class="apii">[-0, +0, –]</span> +<pre>int lua_upvalueindex (int i);</pre> + +<p> +Returns the pseudo-index that represents the <code>i</code>-th upvalue of +the running function (see <a href="#4.4">§4.4</a>). + + + + + +<hr><h3><a name="lua_version"><code>lua_version</code></a></h3><p> +<span class="apii">[-0, +0, –]</span> +<pre>const lua_Number *lua_version (lua_State *L);</pre> + +<p> +Returns the address of the version number +(a C static variable) +stored in the Lua core. +When called with a valid <a href="#lua_State"><code>lua_State</code></a>, +returns the address of the version used to create that state. +When called with <code>NULL</code>, +returns the address of the version running the call. + + + + + +<hr><h3><a name="lua_Writer"><code>lua_Writer</code></a></h3> +<pre>typedef int (*lua_Writer) (lua_State *L, + const void* p, + size_t sz, + void* ud);</pre> + +<p> +The type of the writer function used by <a href="#lua_dump"><code>lua_dump</code></a>. +Every time it produces another piece of chunk, +<a href="#lua_dump"><code>lua_dump</code></a> calls the writer, +passing along the buffer to be written (<code>p</code>), +its size (<code>sz</code>), +and the <code>data</code> parameter supplied to <a href="#lua_dump"><code>lua_dump</code></a>. + + +<p> +The writer returns an error code: +0 means no errors; +any other value means an error and stops <a href="#lua_dump"><code>lua_dump</code></a> from +calling the writer again. + + + + + +<hr><h3><a name="lua_xmove"><code>lua_xmove</code></a></h3><p> +<span class="apii">[-?, +?, –]</span> +<pre>void lua_xmove (lua_State *from, lua_State *to, int n);</pre> + +<p> +Exchange values between different threads of the same state. + + +<p> +This function pops <code>n</code> values from the stack <code>from</code>, +and pushes them onto the stack <code>to</code>. + + + + + +<hr><h3><a name="lua_yield"><code>lua_yield</code></a></h3><p> +<span class="apii">[-?, +?, <em>e</em>]</span> +<pre>int lua_yield (lua_State *L, int nresults);</pre> + +<p> +This function is equivalent to <a href="#lua_yieldk"><code>lua_yieldk</code></a>, +but it has no continuation (see <a href="#4.7">§4.7</a>). +Therefore, when the thread resumes, +it continues the function that called +the function calling <code>lua_yield</code>. + + + + + +<hr><h3><a name="lua_yieldk"><code>lua_yieldk</code></a></h3><p> +<span class="apii">[-?, +?, <em>e</em>]</span> +<pre>int lua_yieldk (lua_State *L, + int nresults, + lua_KContext ctx, + lua_KFunction k);</pre> + +<p> +Yields a coroutine (thread). + + +<p> +When a C function calls <a href="#lua_yieldk"><code>lua_yieldk</code></a>, +the running coroutine suspends its execution, +and the call to <a href="#lua_resume"><code>lua_resume</code></a> that started this coroutine returns. +The parameter <code>nresults</code> is the number of values from the stack +that will be passed as results to <a href="#lua_resume"><code>lua_resume</code></a>. + + +<p> +When the coroutine is resumed again, +Lua calls the given continuation function <code>k</code> to continue +the execution of the C function that yielded (see <a href="#4.7">§4.7</a>). +This continuation function receives the same stack +from the previous function, +with the <code>n</code> results removed and +replaced by the arguments passed to <a href="#lua_resume"><code>lua_resume</code></a>. +Moreover, +the continuation function receives the value <code>ctx</code> +that was passed to <a href="#lua_yieldk"><code>lua_yieldk</code></a>. + + +<p> +Usually, this function does not return; +when the coroutine eventually resumes, +it continues executing the continuation function. +However, there is one special case, +which is when this function is called +from inside a line or a count hook (see <a href="#4.9">§4.9</a>). +In that case, <code>lua_yieldk</code> should be called with no continuation +(probably in the form of <a href="#lua_yield"><code>lua_yield</code></a>) and no results, +and the hook should return immediately after the call. +Lua will yield and, +when the coroutine resumes again, +it will continue the normal execution +of the (Lua) function that triggered the hook. + + +<p> +This function can raise an error if it is called from a thread +with a pending C call with no continuation function, +or it is called from a thread that is not running inside a resume +(e.g., the main thread). + + + + + + + +<h2>4.9 – <a name="4.9">The Debug Interface</a></h2> + +<p> +Lua has no built-in debugging facilities. +Instead, it offers a special interface +by means of functions and <em>hooks</em>. +This interface allows the construction of different +kinds of debuggers, profilers, and other tools +that need "inside information" from the interpreter. + + + +<hr><h3><a name="lua_Debug"><code>lua_Debug</code></a></h3> +<pre>typedef struct lua_Debug { + int event; + const char *name; /* (n) */ + const char *namewhat; /* (n) */ + const char *what; /* (S) */ + const char *source; /* (S) */ + int currentline; /* (l) */ + int linedefined; /* (S) */ + int lastlinedefined; /* (S) */ + unsigned char nups; /* (u) number of upvalues */ + unsigned char nparams; /* (u) number of parameters */ + char isvararg; /* (u) */ + char istailcall; /* (t) */ + char short_src[LUA_IDSIZE]; /* (S) */ + /* private part */ + <em>other fields</em> +} lua_Debug;</pre> + +<p> +A structure used to carry different pieces of +information about a function or an activation record. +<a href="#lua_getstack"><code>lua_getstack</code></a> fills only the private part +of this structure, for later use. +To fill the other fields of <a href="#lua_Debug"><code>lua_Debug</code></a> with useful information, +call <a href="#lua_getinfo"><code>lua_getinfo</code></a>. + + +<p> +The fields of <a href="#lua_Debug"><code>lua_Debug</code></a> have the following meaning: + +<ul> + +<li><b><code>source</code>: </b> +the name of the chunk that created the function. +If <code>source</code> starts with a '<code>@</code>', +it means that the function was defined in a file where +the file name follows the '<code>@</code>'. +If <code>source</code> starts with a '<code>=</code>', +the remainder of its contents describe the source in a user-dependent manner. +Otherwise, +the function was defined in a string where +<code>source</code> is that string. +</li> + +<li><b><code>short_src</code>: </b> +a "printable" version of <code>source</code>, to be used in error messages. +</li> + +<li><b><code>linedefined</code>: </b> +the line number where the definition of the function starts. +</li> + +<li><b><code>lastlinedefined</code>: </b> +the line number where the definition of the function ends. +</li> + +<li><b><code>what</code>: </b> +the string <code>"Lua"</code> if the function is a Lua function, +<code>"C"</code> if it is a C function, +<code>"main"</code> if it is the main part of a chunk. +</li> + +<li><b><code>currentline</code>: </b> +the current line where the given function is executing. +When no line information is available, +<code>currentline</code> is set to -1. +</li> + +<li><b><code>name</code>: </b> +a reasonable name for the given function. +Because functions in Lua are first-class values, +they do not have a fixed name: +some functions can be the value of multiple global variables, +while others can be stored only in a table field. +The <code>lua_getinfo</code> function checks how the function was +called to find a suitable name. +If it cannot find a name, +then <code>name</code> is set to <code>NULL</code>. +</li> + +<li><b><code>namewhat</code>: </b> +explains the <code>name</code> field. +The value of <code>namewhat</code> can be +<code>"global"</code>, <code>"local"</code>, <code>"method"</code>, +<code>"field"</code>, <code>"upvalue"</code>, or <code>""</code> (the empty string), +according to how the function was called. +(Lua uses the empty string when no other option seems to apply.) +</li> + +<li><b><code>istailcall</code>: </b> +true if this function invocation was called by a tail call. +In this case, the caller of this level is not in the stack. +</li> + +<li><b><code>nups</code>: </b> +the number of upvalues of the function. +</li> + +<li><b><code>nparams</code>: </b> +the number of fixed parameters of the function +(always 0 for C functions). +</li> + +<li><b><code>isvararg</code>: </b> +true if the function is a vararg function +(always true for C functions). +</li> + +</ul> + + + + +<hr><h3><a name="lua_gethook"><code>lua_gethook</code></a></h3><p> +<span class="apii">[-0, +0, –]</span> +<pre>lua_Hook lua_gethook (lua_State *L);</pre> + +<p> +Returns the current hook function. + + + + + +<hr><h3><a name="lua_gethookcount"><code>lua_gethookcount</code></a></h3><p> +<span class="apii">[-0, +0, –]</span> +<pre>int lua_gethookcount (lua_State *L);</pre> + +<p> +Returns the current hook count. + + + + + +<hr><h3><a name="lua_gethookmask"><code>lua_gethookmask</code></a></h3><p> +<span class="apii">[-0, +0, –]</span> +<pre>int lua_gethookmask (lua_State *L);</pre> + +<p> +Returns the current hook mask. + + + + + +<hr><h3><a name="lua_getinfo"><code>lua_getinfo</code></a></h3><p> +<span class="apii">[-(0|1), +(0|1|2), <em>e</em>]</span> +<pre>int lua_getinfo (lua_State *L, const char *what, lua_Debug *ar);</pre> + +<p> +Gets information about a specific function or function invocation. + + +<p> +To get information about a function invocation, +the parameter <code>ar</code> must be a valid activation record that was +filled by a previous call to <a href="#lua_getstack"><code>lua_getstack</code></a> or +given as argument to a hook (see <a href="#lua_Hook"><code>lua_Hook</code></a>). + + +<p> +To get information about a function, you push it onto the stack +and start the <code>what</code> string with the character '<code>></code>'. +(In that case, +<code>lua_getinfo</code> pops the function from the top of the stack.) +For instance, to know in which line a function <code>f</code> was defined, +you can write the following code: + +<pre> + lua_Debug ar; + lua_getglobal(L, "f"); /* get global 'f' */ + lua_getinfo(L, ">S", &ar); + printf("%d\n", ar.linedefined); +</pre> + +<p> +Each character in the string <code>what</code> +selects some fields of the structure <code>ar</code> to be filled or +a value to be pushed on the stack: + +<ul> + +<li><b>'<code>n</code>': </b> fills in the field <code>name</code> and <code>namewhat</code>; +</li> + +<li><b>'<code>S</code>': </b> +fills in the fields <code>source</code>, <code>short_src</code>, +<code>linedefined</code>, <code>lastlinedefined</code>, and <code>what</code>; +</li> + +<li><b>'<code>l</code>': </b> fills in the field <code>currentline</code>; +</li> + +<li><b>'<code>t</code>': </b> fills in the field <code>istailcall</code>; +</li> + +<li><b>'<code>u</code>': </b> fills in the fields +<code>nups</code>, <code>nparams</code>, and <code>isvararg</code>; +</li> + +<li><b>'<code>f</code>': </b> +pushes onto the stack the function that is +running at the given level; +</li> + +<li><b>'<code>L</code>': </b> +pushes onto the stack a table whose indices are the +numbers of the lines that are valid on the function. +(A <em>valid line</em> is a line with some associated code, +that is, a line where you can put a break point. +Non-valid lines include empty lines and comments.) + + +<p> +If this option is given together with option '<code>f</code>', +its table is pushed after the function. +</li> + +</ul> + +<p> +This function returns 0 on error +(for instance, an invalid option in <code>what</code>). + + + + + +<hr><h3><a name="lua_getlocal"><code>lua_getlocal</code></a></h3><p> +<span class="apii">[-0, +(0|1), –]</span> +<pre>const char *lua_getlocal (lua_State *L, const lua_Debug *ar, int n);</pre> + +<p> +Gets information about a local variable of +a given activation record or a given function. + + +<p> +In the first case, +the parameter <code>ar</code> must be a valid activation record that was +filled by a previous call to <a href="#lua_getstack"><code>lua_getstack</code></a> or +given as argument to a hook (see <a href="#lua_Hook"><code>lua_Hook</code></a>). +The index <code>n</code> selects which local variable to inspect; +see <a href="#pdf-debug.getlocal"><code>debug.getlocal</code></a> for details about variable indices +and names. + + +<p> +<a href="#lua_getlocal"><code>lua_getlocal</code></a> pushes the variable's value onto the stack +and returns its name. + + +<p> +In the second case, <code>ar</code> must be <code>NULL</code> and the function +to be inspected must be at the top of the stack. +In this case, only parameters of Lua functions are visible +(as there is no information about what variables are active) +and no values are pushed onto the stack. + + +<p> +Returns <code>NULL</code> (and pushes nothing) +when the index is greater than +the number of active local variables. + + + + + +<hr><h3><a name="lua_getstack"><code>lua_getstack</code></a></h3><p> +<span class="apii">[-0, +0, –]</span> +<pre>int lua_getstack (lua_State *L, int level, lua_Debug *ar);</pre> + +<p> +Gets information about the interpreter runtime stack. + + +<p> +This function fills parts of a <a href="#lua_Debug"><code>lua_Debug</code></a> structure with +an identification of the <em>activation record</em> +of the function executing at a given level. +Level 0 is the current running function, +whereas level <em>n+1</em> is the function that has called level <em>n</em> +(except for tail calls, which do not count on the stack). +When there are no errors, <a href="#lua_getstack"><code>lua_getstack</code></a> returns 1; +when called with a level greater than the stack depth, +it returns 0. + + + + + +<hr><h3><a name="lua_getupvalue"><code>lua_getupvalue</code></a></h3><p> +<span class="apii">[-0, +(0|1), –]</span> +<pre>const char *lua_getupvalue (lua_State *L, int funcindex, int n);</pre> + +<p> +Gets information about the <code>n</code>-th upvalue +of the closure at index <code>funcindex</code>. +It pushes the upvalue's value onto the stack +and returns its name. +Returns <code>NULL</code> (and pushes nothing) +when the index <code>n</code> is greater than the number of upvalues. + + +<p> +For C functions, this function uses the empty string <code>""</code> +as a name for all upvalues. +(For Lua functions, +upvalues are the external local variables that the function uses, +and that are consequently included in its closure.) + + +<p> +Upvalues have no particular order, +as they are active through the whole function. +They are numbered in an arbitrary order. + + + + + +<hr><h3><a name="lua_Hook"><code>lua_Hook</code></a></h3> +<pre>typedef void (*lua_Hook) (lua_State *L, lua_Debug *ar);</pre> + +<p> +Type for debugging hook functions. + + +<p> +Whenever a hook is called, its <code>ar</code> argument has its field +<code>event</code> set to the specific event that triggered the hook. +Lua identifies these events with the following constants: +<a name="pdf-LUA_HOOKCALL"><code>LUA_HOOKCALL</code></a>, <a name="pdf-LUA_HOOKRET"><code>LUA_HOOKRET</code></a>, +<a name="pdf-LUA_HOOKTAILCALL"><code>LUA_HOOKTAILCALL</code></a>, <a name="pdf-LUA_HOOKLINE"><code>LUA_HOOKLINE</code></a>, +and <a name="pdf-LUA_HOOKCOUNT"><code>LUA_HOOKCOUNT</code></a>. +Moreover, for line events, the field <code>currentline</code> is also set. +To get the value of any other field in <code>ar</code>, +the hook must call <a href="#lua_getinfo"><code>lua_getinfo</code></a>. + + +<p> +For call events, <code>event</code> can be <code>LUA_HOOKCALL</code>, +the normal value, or <code>LUA_HOOKTAILCALL</code>, for a tail call; +in this case, there will be no corresponding return event. + + +<p> +While Lua is running a hook, it disables other calls to hooks. +Therefore, if a hook calls back Lua to execute a function or a chunk, +this execution occurs without any calls to hooks. + + +<p> +Hook functions cannot have continuations, +that is, they cannot call <a href="#lua_yieldk"><code>lua_yieldk</code></a>, +<a href="#lua_pcallk"><code>lua_pcallk</code></a>, or <a href="#lua_callk"><code>lua_callk</code></a> with a non-null <code>k</code>. + + +<p> +Hook functions can yield under the following conditions: +Only count and line events can yield; +to yield, a hook function must finish its execution +calling <a href="#lua_yield"><code>lua_yield</code></a> with <code>nresults</code> equal to zero +(that is, with no values). + + + + + +<hr><h3><a name="lua_sethook"><code>lua_sethook</code></a></h3><p> +<span class="apii">[-0, +0, –]</span> +<pre>void lua_sethook (lua_State *L, lua_Hook f, int mask, int count);</pre> + +<p> +Sets the debugging hook function. + + +<p> +Argument <code>f</code> is the hook function. +<code>mask</code> specifies on which events the hook will be called: +it is formed by a bitwise OR of the constants +<a name="pdf-LUA_MASKCALL"><code>LUA_MASKCALL</code></a>, +<a name="pdf-LUA_MASKRET"><code>LUA_MASKRET</code></a>, +<a name="pdf-LUA_MASKLINE"><code>LUA_MASKLINE</code></a>, +and <a name="pdf-LUA_MASKCOUNT"><code>LUA_MASKCOUNT</code></a>. +The <code>count</code> argument is only meaningful when the mask +includes <code>LUA_MASKCOUNT</code>. +For each event, the hook is called as explained below: + +<ul> + +<li><b>The call hook: </b> is called when the interpreter calls a function. +The hook is called just after Lua enters the new function, +before the function gets its arguments. +</li> + +<li><b>The return hook: </b> is called when the interpreter returns from a function. +The hook is called just before Lua leaves the function. +There is no standard way to access the values +to be returned by the function. +</li> + +<li><b>The line hook: </b> is called when the interpreter is about to +start the execution of a new line of code, +or when it jumps back in the code (even to the same line). +(This event only happens while Lua is executing a Lua function.) +</li> + +<li><b>The count hook: </b> is called after the interpreter executes every +<code>count</code> instructions. +(This event only happens while Lua is executing a Lua function.) +</li> + +</ul> + +<p> +A hook is disabled by setting <code>mask</code> to zero. + + + + + +<hr><h3><a name="lua_setlocal"><code>lua_setlocal</code></a></h3><p> +<span class="apii">[-(0|1), +0, –]</span> +<pre>const char *lua_setlocal (lua_State *L, const lua_Debug *ar, int n);</pre> + +<p> +Sets the value of a local variable of a given activation record. +It assigns the value at the top of the stack +to the variable and returns its name. +It also pops the value from the stack. + + +<p> +Returns <code>NULL</code> (and pops nothing) +when the index is greater than +the number of active local variables. + + +<p> +Parameters <code>ar</code> and <code>n</code> are as in function <a href="#lua_getlocal"><code>lua_getlocal</code></a>. + + + + + +<hr><h3><a name="lua_setupvalue"><code>lua_setupvalue</code></a></h3><p> +<span class="apii">[-(0|1), +0, –]</span> +<pre>const char *lua_setupvalue (lua_State *L, int funcindex, int n);</pre> + +<p> +Sets the value of a closure's upvalue. +It assigns the value at the top of the stack +to the upvalue and returns its name. +It also pops the value from the stack. + + +<p> +Returns <code>NULL</code> (and pops nothing) +when the index <code>n</code> is greater than the number of upvalues. + + +<p> +Parameters <code>funcindex</code> and <code>n</code> are as in function <a href="#lua_getupvalue"><code>lua_getupvalue</code></a>. + + + + + +<hr><h3><a name="lua_upvalueid"><code>lua_upvalueid</code></a></h3><p> +<span class="apii">[-0, +0, –]</span> +<pre>void *lua_upvalueid (lua_State *L, int funcindex, int n);</pre> + +<p> +Returns a unique identifier for the upvalue numbered <code>n</code> +from the closure at index <code>funcindex</code>. + + +<p> +These unique identifiers allow a program to check whether different +closures share upvalues. +Lua closures that share an upvalue +(that is, that access a same external local variable) +will return identical ids for those upvalue indices. + + +<p> +Parameters <code>funcindex</code> and <code>n</code> are as in function <a href="#lua_getupvalue"><code>lua_getupvalue</code></a>, +but <code>n</code> cannot be greater than the number of upvalues. + + + + + +<hr><h3><a name="lua_upvaluejoin"><code>lua_upvaluejoin</code></a></h3><p> +<span class="apii">[-0, +0, –]</span> +<pre>void lua_upvaluejoin (lua_State *L, int funcindex1, int n1, + int funcindex2, int n2);</pre> + +<p> +Make the <code>n1</code>-th upvalue of the Lua closure at index <code>funcindex1</code> +refer to the <code>n2</code>-th upvalue of the Lua closure at index <code>funcindex2</code>. + + + + + + + +<h1>5 – <a name="5">The Auxiliary Library</a></h1> + +<p> + +The <em>auxiliary library</em> provides several convenient functions +to interface C with Lua. +While the basic API provides the primitive functions for all +interactions between C and Lua, +the auxiliary library provides higher-level functions for some +common tasks. + + +<p> +All functions and types from the auxiliary library +are defined in header file <code>lauxlib.h</code> and +have a prefix <code>luaL_</code>. + + +<p> +All functions in the auxiliary library are built on +top of the basic API, +and so they provide nothing that cannot be done with that API. +Nevertheless, the use of the auxiliary library ensures +more consistency to your code. + + +<p> +Several functions in the auxiliary library use internally some +extra stack slots. +When a function in the auxiliary library uses less than five slots, +it does not check the stack size; +it simply assumes that there are enough slots. + + +<p> +Several functions in the auxiliary library are used to +check C function arguments. +Because the error message is formatted for arguments +(e.g., "<code>bad argument #1</code>"), +you should not use these functions for other stack values. + + +<p> +Functions called <code>luaL_check*</code> +always raise an error if the check is not satisfied. + + + +<h2>5.1 – <a name="5.1">Functions and Types</a></h2> + +<p> +Here we list all functions and types from the auxiliary library +in alphabetical order. + + + +<hr><h3><a name="luaL_addchar"><code>luaL_addchar</code></a></h3><p> +<span class="apii">[-?, +?, <em>m</em>]</span> +<pre>void luaL_addchar (luaL_Buffer *B, char c);</pre> + +<p> +Adds the byte <code>c</code> to the buffer <code>B</code> +(see <a href="#luaL_Buffer"><code>luaL_Buffer</code></a>). + + + + + +<hr><h3><a name="luaL_addlstring"><code>luaL_addlstring</code></a></h3><p> +<span class="apii">[-?, +?, <em>m</em>]</span> +<pre>void luaL_addlstring (luaL_Buffer *B, const char *s, size_t l);</pre> + +<p> +Adds the string pointed to by <code>s</code> with length <code>l</code> to +the buffer <code>B</code> +(see <a href="#luaL_Buffer"><code>luaL_Buffer</code></a>). +The string can contain embedded zeros. + + + + + +<hr><h3><a name="luaL_addsize"><code>luaL_addsize</code></a></h3><p> +<span class="apii">[-?, +?, –]</span> +<pre>void luaL_addsize (luaL_Buffer *B, size_t n);</pre> + +<p> +Adds to the buffer <code>B</code> (see <a href="#luaL_Buffer"><code>luaL_Buffer</code></a>) +a string of length <code>n</code> previously copied to the +buffer area (see <a href="#luaL_prepbuffer"><code>luaL_prepbuffer</code></a>). + + + + + +<hr><h3><a name="luaL_addstring"><code>luaL_addstring</code></a></h3><p> +<span class="apii">[-?, +?, <em>m</em>]</span> +<pre>void luaL_addstring (luaL_Buffer *B, const char *s);</pre> + +<p> +Adds the zero-terminated string pointed to by <code>s</code> +to the buffer <code>B</code> +(see <a href="#luaL_Buffer"><code>luaL_Buffer</code></a>). + + + + + +<hr><h3><a name="luaL_addvalue"><code>luaL_addvalue</code></a></h3><p> +<span class="apii">[-1, +?, <em>m</em>]</span> +<pre>void luaL_addvalue (luaL_Buffer *B);</pre> + +<p> +Adds the value at the top of the stack +to the buffer <code>B</code> +(see <a href="#luaL_Buffer"><code>luaL_Buffer</code></a>). +Pops the value. + + +<p> +This is the only function on string buffers that can (and must) +be called with an extra element on the stack, +which is the value to be added to the buffer. + + + + + +<hr><h3><a name="luaL_argcheck"><code>luaL_argcheck</code></a></h3><p> +<span class="apii">[-0, +0, <em>v</em>]</span> +<pre>void luaL_argcheck (lua_State *L, + int cond, + int arg, + const char *extramsg);</pre> + +<p> +Checks whether <code>cond</code> is true. +If it is not, raises an error with a standard message (see <a href="#luaL_argerror"><code>luaL_argerror</code></a>). + + + + + +<hr><h3><a name="luaL_argerror"><code>luaL_argerror</code></a></h3><p> +<span class="apii">[-0, +0, <em>v</em>]</span> +<pre>int luaL_argerror (lua_State *L, int arg, const char *extramsg);</pre> + +<p> +Raises an error reporting a problem with argument <code>arg</code> +of the C function that called it, +using a standard message +that includes <code>extramsg</code> as a comment: + +<pre> + bad argument #<em>arg</em> to '<em>funcname</em>' (<em>extramsg</em>) +</pre><p> +This function never returns. + + + + + +<hr><h3><a name="luaL_Buffer"><code>luaL_Buffer</code></a></h3> +<pre>typedef struct luaL_Buffer luaL_Buffer;</pre> + +<p> +Type for a <em>string buffer</em>. + + +<p> +A string buffer allows C code to build Lua strings piecemeal. +Its pattern of use is as follows: + +<ul> + +<li>First declare a variable <code>b</code> of type <a href="#luaL_Buffer"><code>luaL_Buffer</code></a>.</li> + +<li>Then initialize it with a call <code>luaL_buffinit(L, &b)</code>.</li> + +<li> +Then add string pieces to the buffer calling any of +the <code>luaL_add*</code> functions. +</li> + +<li> +Finish by calling <code>luaL_pushresult(&b)</code>. +This call leaves the final string on the top of the stack. +</li> + +</ul> + +<p> +If you know beforehand the total size of the resulting string, +you can use the buffer like this: + +<ul> + +<li>First declare a variable <code>b</code> of type <a href="#luaL_Buffer"><code>luaL_Buffer</code></a>.</li> + +<li>Then initialize it and preallocate a space of +size <code>sz</code> with a call <code>luaL_buffinitsize(L, &b, sz)</code>.</li> + +<li>Then copy the string into that space.</li> + +<li> +Finish by calling <code>luaL_pushresultsize(&b, sz)</code>, +where <code>sz</code> is the total size of the resulting string +copied into that space. +</li> + +</ul> + +<p> +During its normal operation, +a string buffer uses a variable number of stack slots. +So, while using a buffer, you cannot assume that you know where +the top of the stack is. +You can use the stack between successive calls to buffer operations +as long as that use is balanced; +that is, +when you call a buffer operation, +the stack is at the same level +it was immediately after the previous buffer operation. +(The only exception to this rule is <a href="#luaL_addvalue"><code>luaL_addvalue</code></a>.) +After calling <a href="#luaL_pushresult"><code>luaL_pushresult</code></a> the stack is back to its +level when the buffer was initialized, +plus the final string on its top. + + + + + +<hr><h3><a name="luaL_buffinit"><code>luaL_buffinit</code></a></h3><p> +<span class="apii">[-0, +0, –]</span> +<pre>void luaL_buffinit (lua_State *L, luaL_Buffer *B);</pre> + +<p> +Initializes a buffer <code>B</code>. +This function does not allocate any space; +the buffer must be declared as a variable +(see <a href="#luaL_Buffer"><code>luaL_Buffer</code></a>). + + + + + +<hr><h3><a name="luaL_buffinitsize"><code>luaL_buffinitsize</code></a></h3><p> +<span class="apii">[-?, +?, <em>m</em>]</span> +<pre>char *luaL_buffinitsize (lua_State *L, luaL_Buffer *B, size_t sz);</pre> + +<p> +Equivalent to the sequence +<a href="#luaL_buffinit"><code>luaL_buffinit</code></a>, <a href="#luaL_prepbuffsize"><code>luaL_prepbuffsize</code></a>. + + + + + +<hr><h3><a name="luaL_callmeta"><code>luaL_callmeta</code></a></h3><p> +<span class="apii">[-0, +(0|1), <em>e</em>]</span> +<pre>int luaL_callmeta (lua_State *L, int obj, const char *e);</pre> + +<p> +Calls a metamethod. + + +<p> +If the object at index <code>obj</code> has a metatable and this +metatable has a field <code>e</code>, +this function calls this field passing the object as its only argument. +In this case this function returns true and pushes onto the +stack the value returned by the call. +If there is no metatable or no metamethod, +this function returns false (without pushing any value on the stack). + + + + + +<hr><h3><a name="luaL_checkany"><code>luaL_checkany</code></a></h3><p> +<span class="apii">[-0, +0, <em>v</em>]</span> +<pre>void luaL_checkany (lua_State *L, int arg);</pre> + +<p> +Checks whether the function has an argument +of any type (including <b>nil</b>) at position <code>arg</code>. + + + + + +<hr><h3><a name="luaL_checkinteger"><code>luaL_checkinteger</code></a></h3><p> +<span class="apii">[-0, +0, <em>v</em>]</span> +<pre>lua_Integer luaL_checkinteger (lua_State *L, int arg);</pre> + +<p> +Checks whether the function argument <code>arg</code> is an integer +(or can be converted to an integer) +and returns this integer cast to a <a href="#lua_Integer"><code>lua_Integer</code></a>. + + + + + +<hr><h3><a name="luaL_checklstring"><code>luaL_checklstring</code></a></h3><p> +<span class="apii">[-0, +0, <em>v</em>]</span> +<pre>const char *luaL_checklstring (lua_State *L, int arg, size_t *l);</pre> + +<p> +Checks whether the function argument <code>arg</code> is a string +and returns this string; +if <code>l</code> is not <code>NULL</code> fills <code>*l</code> +with the string's length. + + +<p> +This function uses <a href="#lua_tolstring"><code>lua_tolstring</code></a> to get its result, +so all conversions and caveats of that function apply here. + + + + + +<hr><h3><a name="luaL_checknumber"><code>luaL_checknumber</code></a></h3><p> +<span class="apii">[-0, +0, <em>v</em>]</span> +<pre>lua_Number luaL_checknumber (lua_State *L, int arg);</pre> + +<p> +Checks whether the function argument <code>arg</code> is a number +and returns this number. + + + + + +<hr><h3><a name="luaL_checkoption"><code>luaL_checkoption</code></a></h3><p> +<span class="apii">[-0, +0, <em>v</em>]</span> +<pre>int luaL_checkoption (lua_State *L, + int arg, + const char *def, + const char *const lst[]);</pre> + +<p> +Checks whether the function argument <code>arg</code> is a string and +searches for this string in the array <code>lst</code> +(which must be NULL-terminated). +Returns the index in the array where the string was found. +Raises an error if the argument is not a string or +if the string cannot be found. + + +<p> +If <code>def</code> is not <code>NULL</code>, +the function uses <code>def</code> as a default value when +there is no argument <code>arg</code> or when this argument is <b>nil</b>. + + +<p> +This is a useful function for mapping strings to C enums. +(The usual convention in Lua libraries is +to use strings instead of numbers to select options.) + + + + + +<hr><h3><a name="luaL_checkstack"><code>luaL_checkstack</code></a></h3><p> +<span class="apii">[-0, +0, <em>v</em>]</span> +<pre>void luaL_checkstack (lua_State *L, int sz, const char *msg);</pre> + +<p> +Grows the stack size to <code>top + sz</code> elements, +raising an error if the stack cannot grow to that size. +<code>msg</code> is an additional text to go into the error message +(or <code>NULL</code> for no additional text). + + + + + +<hr><h3><a name="luaL_checkstring"><code>luaL_checkstring</code></a></h3><p> +<span class="apii">[-0, +0, <em>v</em>]</span> +<pre>const char *luaL_checkstring (lua_State *L, int arg);</pre> + +<p> +Checks whether the function argument <code>arg</code> is a string +and returns this string. + + +<p> +This function uses <a href="#lua_tolstring"><code>lua_tolstring</code></a> to get its result, +so all conversions and caveats of that function apply here. + + + + + +<hr><h3><a name="luaL_checktype"><code>luaL_checktype</code></a></h3><p> +<span class="apii">[-0, +0, <em>v</em>]</span> +<pre>void luaL_checktype (lua_State *L, int arg, int t);</pre> + +<p> +Checks whether the function argument <code>arg</code> has type <code>t</code>. +See <a href="#lua_type"><code>lua_type</code></a> for the encoding of types for <code>t</code>. + + + + + +<hr><h3><a name="luaL_checkudata"><code>luaL_checkudata</code></a></h3><p> +<span class="apii">[-0, +0, <em>v</em>]</span> +<pre>void *luaL_checkudata (lua_State *L, int arg, const char *tname);</pre> + +<p> +Checks whether the function argument <code>arg</code> is a userdata +of the type <code>tname</code> (see <a href="#luaL_newmetatable"><code>luaL_newmetatable</code></a>) and +returns the userdata address (see <a href="#lua_touserdata"><code>lua_touserdata</code></a>). + + + + + +<hr><h3><a name="luaL_checkversion"><code>luaL_checkversion</code></a></h3><p> +<span class="apii">[-0, +0, <em>v</em>]</span> +<pre>void luaL_checkversion (lua_State *L);</pre> + +<p> +Checks whether the core running the call, +the core that created the Lua state, +and the code making the call are all using the same version of Lua. +Also checks whether the core running the call +and the core that created the Lua state +are using the same address space. + + + + + +<hr><h3><a name="luaL_dofile"><code>luaL_dofile</code></a></h3><p> +<span class="apii">[-0, +?, <em>e</em>]</span> +<pre>int luaL_dofile (lua_State *L, const char *filename);</pre> + +<p> +Loads and runs the given file. +It is defined as the following macro: + +<pre> + (luaL_loadfile(L, filename) || lua_pcall(L, 0, LUA_MULTRET, 0)) +</pre><p> +It returns false if there are no errors +or true in case of errors. + + + + + +<hr><h3><a name="luaL_dostring"><code>luaL_dostring</code></a></h3><p> +<span class="apii">[-0, +?, –]</span> +<pre>int luaL_dostring (lua_State *L, const char *str);</pre> + +<p> +Loads and runs the given string. +It is defined as the following macro: + +<pre> + (luaL_loadstring(L, str) || lua_pcall(L, 0, LUA_MULTRET, 0)) +</pre><p> +It returns false if there are no errors +or true in case of errors. + + + + + +<hr><h3><a name="luaL_error"><code>luaL_error</code></a></h3><p> +<span class="apii">[-0, +0, <em>v</em>]</span> +<pre>int luaL_error (lua_State *L, const char *fmt, ...);</pre> + +<p> +Raises an error. +The error message format is given by <code>fmt</code> +plus any extra arguments, +following the same rules of <a href="#lua_pushfstring"><code>lua_pushfstring</code></a>. +It also adds at the beginning of the message the file name and +the line number where the error occurred, +if this information is available. + + +<p> +This function never returns, +but it is an idiom to use it in C functions +as <code>return luaL_error(<em>args</em>)</code>. + + + + + +<hr><h3><a name="luaL_execresult"><code>luaL_execresult</code></a></h3><p> +<span class="apii">[-0, +3, <em>m</em>]</span> +<pre>int luaL_execresult (lua_State *L, int stat);</pre> + +<p> +This function produces the return values for +process-related functions in the standard library +(<a href="#pdf-os.execute"><code>os.execute</code></a> and <a href="#pdf-io.close"><code>io.close</code></a>). + + + + + +<hr><h3><a name="luaL_fileresult"><code>luaL_fileresult</code></a></h3><p> +<span class="apii">[-0, +(1|3), <em>m</em>]</span> +<pre>int luaL_fileresult (lua_State *L, int stat, const char *fname);</pre> + +<p> +This function produces the return values for +file-related functions in the standard library +(<a href="#pdf-io.open"><code>io.open</code></a>, <a href="#pdf-os.rename"><code>os.rename</code></a>, <a href="#pdf-file:seek"><code>file:seek</code></a>, etc.). + + + + + +<hr><h3><a name="luaL_getmetafield"><code>luaL_getmetafield</code></a></h3><p> +<span class="apii">[-0, +(0|1), <em>m</em>]</span> +<pre>int luaL_getmetafield (lua_State *L, int obj, const char *e);</pre> + +<p> +Pushes onto the stack the field <code>e</code> from the metatable +of the object at index <code>obj</code> and returns the type of the pushed value. +If the object does not have a metatable, +or if the metatable does not have this field, +pushes nothing and returns <code>LUA_TNIL</code>. + + + + + +<hr><h3><a name="luaL_getmetatable"><code>luaL_getmetatable</code></a></h3><p> +<span class="apii">[-0, +1, <em>m</em>]</span> +<pre>int luaL_getmetatable (lua_State *L, const char *tname);</pre> + +<p> +Pushes onto the stack the metatable associated with name <code>tname</code> +in the registry (see <a href="#luaL_newmetatable"><code>luaL_newmetatable</code></a>) +(<b>nil</b> if there is no metatable associated with that name). +Returns the type of the pushed value. + + + + + +<hr><h3><a name="luaL_getsubtable"><code>luaL_getsubtable</code></a></h3><p> +<span class="apii">[-0, +1, <em>e</em>]</span> +<pre>int luaL_getsubtable (lua_State *L, int idx, const char *fname);</pre> + +<p> +Ensures that the value <code>t[fname]</code>, +where <code>t</code> is the value at index <code>idx</code>, +is a table, +and pushes that table onto the stack. +Returns true if it finds a previous table there +and false if it creates a new table. + + + + + +<hr><h3><a name="luaL_gsub"><code>luaL_gsub</code></a></h3><p> +<span class="apii">[-0, +1, <em>m</em>]</span> +<pre>const char *luaL_gsub (lua_State *L, + const char *s, + const char *p, + const char *r);</pre> + +<p> +Creates a copy of string <code>s</code> by replacing +any occurrence of the string <code>p</code> +with the string <code>r</code>. +Pushes the resulting string on the stack and returns it. + + + + + +<hr><h3><a name="luaL_len"><code>luaL_len</code></a></h3><p> +<span class="apii">[-0, +0, <em>e</em>]</span> +<pre>lua_Integer luaL_len (lua_State *L, int index);</pre> + +<p> +Returns the "length" of the value at the given index +as a number; +it is equivalent to the '<code>#</code>' operator in Lua (see <a href="#3.4.7">§3.4.7</a>). +Raises an error if the result of the operation is not an integer. +(This case only can happen through metamethods.) + + + + + +<hr><h3><a name="luaL_loadbuffer"><code>luaL_loadbuffer</code></a></h3><p> +<span class="apii">[-0, +1, –]</span> +<pre>int luaL_loadbuffer (lua_State *L, + const char *buff, + size_t sz, + const char *name);</pre> + +<p> +Equivalent to <a href="#luaL_loadbufferx"><code>luaL_loadbufferx</code></a> with <code>mode</code> equal to <code>NULL</code>. + + + + + +<hr><h3><a name="luaL_loadbufferx"><code>luaL_loadbufferx</code></a></h3><p> +<span class="apii">[-0, +1, –]</span> +<pre>int luaL_loadbufferx (lua_State *L, + const char *buff, + size_t sz, + const char *name, + const char *mode);</pre> + +<p> +Loads a buffer as a Lua chunk. +This function uses <a href="#lua_load"><code>lua_load</code></a> to load the chunk in the +buffer pointed to by <code>buff</code> with size <code>sz</code>. + + +<p> +This function returns the same results as <a href="#lua_load"><code>lua_load</code></a>. +<code>name</code> is the chunk name, +used for debug information and error messages. +The string <code>mode</code> works as in function <a href="#lua_load"><code>lua_load</code></a>. + + + + + +<hr><h3><a name="luaL_loadfile"><code>luaL_loadfile</code></a></h3><p> +<span class="apii">[-0, +1, <em>m</em>]</span> +<pre>int luaL_loadfile (lua_State *L, const char *filename);</pre> + +<p> +Equivalent to <a href="#luaL_loadfilex"><code>luaL_loadfilex</code></a> with <code>mode</code> equal to <code>NULL</code>. + + + + + +<hr><h3><a name="luaL_loadfilex"><code>luaL_loadfilex</code></a></h3><p> +<span class="apii">[-0, +1, <em>m</em>]</span> +<pre>int luaL_loadfilex (lua_State *L, const char *filename, + const char *mode);</pre> + +<p> +Loads a file as a Lua chunk. +This function uses <a href="#lua_load"><code>lua_load</code></a> to load the chunk in the file +named <code>filename</code>. +If <code>filename</code> is <code>NULL</code>, +then it loads from the standard input. +The first line in the file is ignored if it starts with a <code>#</code>. + + +<p> +The string <code>mode</code> works as in function <a href="#lua_load"><code>lua_load</code></a>. + + +<p> +This function returns the same results as <a href="#lua_load"><code>lua_load</code></a>, +but it has an extra error code <a name="pdf-LUA_ERRFILE"><code>LUA_ERRFILE</code></a> +for file-related errors +(e.g., it cannot open or read the file). + + +<p> +As <a href="#lua_load"><code>lua_load</code></a>, this function only loads the chunk; +it does not run it. + + + + + +<hr><h3><a name="luaL_loadstring"><code>luaL_loadstring</code></a></h3><p> +<span class="apii">[-0, +1, –]</span> +<pre>int luaL_loadstring (lua_State *L, const char *s);</pre> + +<p> +Loads a string as a Lua chunk. +This function uses <a href="#lua_load"><code>lua_load</code></a> to load the chunk in +the zero-terminated string <code>s</code>. + + +<p> +This function returns the same results as <a href="#lua_load"><code>lua_load</code></a>. + + +<p> +Also as <a href="#lua_load"><code>lua_load</code></a>, this function only loads the chunk; +it does not run it. + + + + + +<hr><h3><a name="luaL_newlib"><code>luaL_newlib</code></a></h3><p> +<span class="apii">[-0, +1, <em>m</em>]</span> +<pre>void luaL_newlib (lua_State *L, const luaL_Reg l[]);</pre> + +<p> +Creates a new table and registers there +the functions in list <code>l</code>. + + +<p> +It is implemented as the following macro: + +<pre> + (luaL_newlibtable(L,l), luaL_setfuncs(L,l,0)) +</pre><p> +The array <code>l</code> must be the actual array, +not a pointer to it. + + + + + +<hr><h3><a name="luaL_newlibtable"><code>luaL_newlibtable</code></a></h3><p> +<span class="apii">[-0, +1, <em>m</em>]</span> +<pre>void luaL_newlibtable (lua_State *L, const luaL_Reg l[]);</pre> + +<p> +Creates a new table with a size optimized +to store all entries in the array <code>l</code> +(but does not actually store them). +It is intended to be used in conjunction with <a href="#luaL_setfuncs"><code>luaL_setfuncs</code></a> +(see <a href="#luaL_newlib"><code>luaL_newlib</code></a>). + + +<p> +It is implemented as a macro. +The array <code>l</code> must be the actual array, +not a pointer to it. + + + + + +<hr><h3><a name="luaL_newmetatable"><code>luaL_newmetatable</code></a></h3><p> +<span class="apii">[-0, +1, <em>m</em>]</span> +<pre>int luaL_newmetatable (lua_State *L, const char *tname);</pre> + +<p> +If the registry already has the key <code>tname</code>, +returns 0. +Otherwise, +creates a new table to be used as a metatable for userdata, +adds to this new table the pair <code>__name = tname</code>, +adds to the registry the pair <code>[tname] = new table</code>, +and returns 1. +(The entry <code>__name</code> is used by some error-reporting functions.) + + +<p> +In both cases pushes onto the stack the final value associated +with <code>tname</code> in the registry. + + + + + +<hr><h3><a name="luaL_newstate"><code>luaL_newstate</code></a></h3><p> +<span class="apii">[-0, +0, –]</span> +<pre>lua_State *luaL_newstate (void);</pre> + +<p> +Creates a new Lua state. +It calls <a href="#lua_newstate"><code>lua_newstate</code></a> with an +allocator based on the standard C <code>realloc</code> function +and then sets a panic function (see <a href="#4.6">§4.6</a>) that prints +an error message to the standard error output in case of fatal +errors. + + +<p> +Returns the new state, +or <code>NULL</code> if there is a memory allocation error. + + + + + +<hr><h3><a name="luaL_openlibs"><code>luaL_openlibs</code></a></h3><p> +<span class="apii">[-0, +0, <em>e</em>]</span> +<pre>void luaL_openlibs (lua_State *L);</pre> + +<p> +Opens all standard Lua libraries into the given state. + + + + + +<hr><h3><a name="luaL_opt"><code>luaL_opt</code></a></h3><p> +<span class="apii">[-0, +0, <em>e</em>]</span> +<pre>T luaL_opt (L, func, arg, dflt);</pre> + +<p> +This macro is defined as follows: + +<pre> + (lua_isnoneornil(L,(arg)) ? (dflt) : func(L,(arg))) +</pre><p> +In words, if the argument <code>arg</code> is nil or absent, +the macro results in the default <code>dflt</code>. +Otherwise, it results in the result of calling <code>func</code> +with the state <code>L</code> and the argument index <code>arg</code> as +arguments. +Note that it evaluates the expression <code>dflt</code> only if needed. + + + + + +<hr><h3><a name="luaL_optinteger"><code>luaL_optinteger</code></a></h3><p> +<span class="apii">[-0, +0, <em>v</em>]</span> +<pre>lua_Integer luaL_optinteger (lua_State *L, + int arg, + lua_Integer d);</pre> + +<p> +If the function argument <code>arg</code> is an integer +(or convertible to an integer), +returns this integer. +If this argument is absent or is <b>nil</b>, +returns <code>d</code>. +Otherwise, raises an error. + + + + + +<hr><h3><a name="luaL_optlstring"><code>luaL_optlstring</code></a></h3><p> +<span class="apii">[-0, +0, <em>v</em>]</span> +<pre>const char *luaL_optlstring (lua_State *L, + int arg, + const char *d, + size_t *l);</pre> + +<p> +If the function argument <code>arg</code> is a string, +returns this string. +If this argument is absent or is <b>nil</b>, +returns <code>d</code>. +Otherwise, raises an error. + + +<p> +If <code>l</code> is not <code>NULL</code>, +fills the position <code>*l</code> with the result's length. +If the result is <code>NULL</code> +(only possible when returning <code>d</code> and <code>d == NULL</code>), +its length is considered zero. + + +<p> +This function uses <a href="#lua_tolstring"><code>lua_tolstring</code></a> to get its result, +so all conversions and caveats of that function apply here. + + + + + +<hr><h3><a name="luaL_optnumber"><code>luaL_optnumber</code></a></h3><p> +<span class="apii">[-0, +0, <em>v</em>]</span> +<pre>lua_Number luaL_optnumber (lua_State *L, int arg, lua_Number d);</pre> + +<p> +If the function argument <code>arg</code> is a number, +returns this number. +If this argument is absent or is <b>nil</b>, +returns <code>d</code>. +Otherwise, raises an error. + + + + + +<hr><h3><a name="luaL_optstring"><code>luaL_optstring</code></a></h3><p> +<span class="apii">[-0, +0, <em>v</em>]</span> +<pre>const char *luaL_optstring (lua_State *L, + int arg, + const char *d);</pre> + +<p> +If the function argument <code>arg</code> is a string, +returns this string. +If this argument is absent or is <b>nil</b>, +returns <code>d</code>. +Otherwise, raises an error. + + + + + +<hr><h3><a name="luaL_prepbuffer"><code>luaL_prepbuffer</code></a></h3><p> +<span class="apii">[-?, +?, <em>m</em>]</span> +<pre>char *luaL_prepbuffer (luaL_Buffer *B);</pre> + +<p> +Equivalent to <a href="#luaL_prepbuffsize"><code>luaL_prepbuffsize</code></a> +with the predefined size <a name="pdf-LUAL_BUFFERSIZE"><code>LUAL_BUFFERSIZE</code></a>. + + + + + +<hr><h3><a name="luaL_prepbuffsize"><code>luaL_prepbuffsize</code></a></h3><p> +<span class="apii">[-?, +?, <em>m</em>]</span> +<pre>char *luaL_prepbuffsize (luaL_Buffer *B, size_t sz);</pre> + +<p> +Returns an address to a space of size <code>sz</code> +where you can copy a string to be added to buffer <code>B</code> +(see <a href="#luaL_Buffer"><code>luaL_Buffer</code></a>). +After copying the string into this space you must call +<a href="#luaL_addsize"><code>luaL_addsize</code></a> with the size of the string to actually add +it to the buffer. + + + + + +<hr><h3><a name="luaL_pushresult"><code>luaL_pushresult</code></a></h3><p> +<span class="apii">[-?, +1, <em>m</em>]</span> +<pre>void luaL_pushresult (luaL_Buffer *B);</pre> + +<p> +Finishes the use of buffer <code>B</code> leaving the final string on +the top of the stack. + + + + + +<hr><h3><a name="luaL_pushresultsize"><code>luaL_pushresultsize</code></a></h3><p> +<span class="apii">[-?, +1, <em>m</em>]</span> +<pre>void luaL_pushresultsize (luaL_Buffer *B, size_t sz);</pre> + +<p> +Equivalent to the sequence <a href="#luaL_addsize"><code>luaL_addsize</code></a>, <a href="#luaL_pushresult"><code>luaL_pushresult</code></a>. + + + + + +<hr><h3><a name="luaL_ref"><code>luaL_ref</code></a></h3><p> +<span class="apii">[-1, +0, <em>m</em>]</span> +<pre>int luaL_ref (lua_State *L, int t);</pre> + +<p> +Creates and returns a <em>reference</em>, +in the table at index <code>t</code>, +for the object at the top of the stack (and pops the object). + + +<p> +A reference is a unique integer key. +As long as you do not manually add integer keys into table <code>t</code>, +<a href="#luaL_ref"><code>luaL_ref</code></a> ensures the uniqueness of the key it returns. +You can retrieve an object referred by reference <code>r</code> +by calling <code>lua_rawgeti(L, t, r)</code>. +Function <a href="#luaL_unref"><code>luaL_unref</code></a> frees a reference and its associated object. + + +<p> +If the object at the top of the stack is <b>nil</b>, +<a href="#luaL_ref"><code>luaL_ref</code></a> returns the constant <a name="pdf-LUA_REFNIL"><code>LUA_REFNIL</code></a>. +The constant <a name="pdf-LUA_NOREF"><code>LUA_NOREF</code></a> is guaranteed to be different +from any reference returned by <a href="#luaL_ref"><code>luaL_ref</code></a>. + + + + + +<hr><h3><a name="luaL_Reg"><code>luaL_Reg</code></a></h3> +<pre>typedef struct luaL_Reg { + const char *name; + lua_CFunction func; +} luaL_Reg;</pre> + +<p> +Type for arrays of functions to be registered by +<a href="#luaL_setfuncs"><code>luaL_setfuncs</code></a>. +<code>name</code> is the function name and <code>func</code> is a pointer to +the function. +Any array of <a href="#luaL_Reg"><code>luaL_Reg</code></a> must end with a sentinel entry +in which both <code>name</code> and <code>func</code> are <code>NULL</code>. + + + + + +<hr><h3><a name="luaL_requiref"><code>luaL_requiref</code></a></h3><p> +<span class="apii">[-0, +1, <em>e</em>]</span> +<pre>void luaL_requiref (lua_State *L, const char *modname, + lua_CFunction openf, int glb);</pre> + +<p> +If <code>modname</code> is not already present in <a href="#pdf-package.loaded"><code>package.loaded</code></a>, +calls function <code>openf</code> with string <code>modname</code> as an argument +and sets the call result in <code>package.loaded[modname]</code>, +as if that function has been called through <a href="#pdf-require"><code>require</code></a>. + + +<p> +If <code>glb</code> is true, +also stores the module into global <code>modname</code>. + + +<p> +Leaves a copy of the module on the stack. + + + + + +<hr><h3><a name="luaL_setfuncs"><code>luaL_setfuncs</code></a></h3><p> +<span class="apii">[-nup, +0, <em>m</em>]</span> +<pre>void luaL_setfuncs (lua_State *L, const luaL_Reg *l, int nup);</pre> + +<p> +Registers all functions in the array <code>l</code> +(see <a href="#luaL_Reg"><code>luaL_Reg</code></a>) into the table on the top of the stack +(below optional upvalues, see next). + + +<p> +When <code>nup</code> is not zero, +all functions are created sharing <code>nup</code> upvalues, +which must be previously pushed on the stack +on top of the library table. +These values are popped from the stack after the registration. + + + + + +<hr><h3><a name="luaL_setmetatable"><code>luaL_setmetatable</code></a></h3><p> +<span class="apii">[-0, +0, –]</span> +<pre>void luaL_setmetatable (lua_State *L, const char *tname);</pre> + +<p> +Sets the metatable of the object at the top of the stack +as the metatable associated with name <code>tname</code> +in the registry (see <a href="#luaL_newmetatable"><code>luaL_newmetatable</code></a>). + + + + + +<hr><h3><a name="luaL_Stream"><code>luaL_Stream</code></a></h3> +<pre>typedef struct luaL_Stream { + FILE *f; + lua_CFunction closef; +} luaL_Stream;</pre> + +<p> +The standard representation for file handles, +which is used by the standard I/O library. + + +<p> +A file handle is implemented as a full userdata, +with a metatable called <code>LUA_FILEHANDLE</code> +(where <code>LUA_FILEHANDLE</code> is a macro with the actual metatable's name). +The metatable is created by the I/O library +(see <a href="#luaL_newmetatable"><code>luaL_newmetatable</code></a>). + + +<p> +This userdata must start with the structure <code>luaL_Stream</code>; +it can contain other data after this initial structure. +Field <code>f</code> points to the corresponding C stream +(or it can be <code>NULL</code> to indicate an incompletely created handle). +Field <code>closef</code> points to a Lua function +that will be called to close the stream +when the handle is closed or collected; +this function receives the file handle as its sole argument and +must return either <b>true</b> (in case of success) +or <b>nil</b> plus an error message (in case of error). +Once Lua calls this field, +it changes the field value to <code>NULL</code> +to signal that the handle is closed. + + + + + +<hr><h3><a name="luaL_testudata"><code>luaL_testudata</code></a></h3><p> +<span class="apii">[-0, +0, <em>m</em>]</span> +<pre>void *luaL_testudata (lua_State *L, int arg, const char *tname);</pre> + +<p> +This function works like <a href="#luaL_checkudata"><code>luaL_checkudata</code></a>, +except that, when the test fails, +it returns <code>NULL</code> instead of raising an error. + + + + + +<hr><h3><a name="luaL_tolstring"><code>luaL_tolstring</code></a></h3><p> +<span class="apii">[-0, +1, <em>e</em>]</span> +<pre>const char *luaL_tolstring (lua_State *L, int idx, size_t *len);</pre> + +<p> +Converts any Lua value at the given index to a C string +in a reasonable format. +The resulting string is pushed onto the stack and also +returned by the function. +If <code>len</code> is not <code>NULL</code>, +the function also sets <code>*len</code> with the string length. + + +<p> +If the value has a metatable with a <code>__tostring</code> field, +then <code>luaL_tolstring</code> calls the corresponding metamethod +with the value as argument, +and uses the result of the call as its result. + + + + + +<hr><h3><a name="luaL_traceback"><code>luaL_traceback</code></a></h3><p> +<span class="apii">[-0, +1, <em>m</em>]</span> +<pre>void luaL_traceback (lua_State *L, lua_State *L1, const char *msg, + int level);</pre> + +<p> +Creates and pushes a traceback of the stack <code>L1</code>. +If <code>msg</code> is not <code>NULL</code> it is appended +at the beginning of the traceback. +The <code>level</code> parameter tells at which level +to start the traceback. + + + + + +<hr><h3><a name="luaL_typename"><code>luaL_typename</code></a></h3><p> +<span class="apii">[-0, +0, –]</span> +<pre>const char *luaL_typename (lua_State *L, int index);</pre> + +<p> +Returns the name of the type of the value at the given index. + + + + + +<hr><h3><a name="luaL_unref"><code>luaL_unref</code></a></h3><p> +<span class="apii">[-0, +0, –]</span> +<pre>void luaL_unref (lua_State *L, int t, int ref);</pre> + +<p> +Releases reference <code>ref</code> from the table at index <code>t</code> +(see <a href="#luaL_ref"><code>luaL_ref</code></a>). +The entry is removed from the table, +so that the referred object can be collected. +The reference <code>ref</code> is also freed to be used again. + + +<p> +If <code>ref</code> is <a href="#pdf-LUA_NOREF"><code>LUA_NOREF</code></a> or <a href="#pdf-LUA_REFNIL"><code>LUA_REFNIL</code></a>, +<a href="#luaL_unref"><code>luaL_unref</code></a> does nothing. + + + + + +<hr><h3><a name="luaL_where"><code>luaL_where</code></a></h3><p> +<span class="apii">[-0, +1, <em>m</em>]</span> +<pre>void luaL_where (lua_State *L, int lvl);</pre> + +<p> +Pushes onto the stack a string identifying the current position +of the control at level <code>lvl</code> in the call stack. +Typically this string has the following format: + +<pre> + <em>chunkname</em>:<em>currentline</em>: +</pre><p> +Level 0 is the running function, +level 1 is the function that called the running function, +etc. + + +<p> +This function is used to build a prefix for error messages. + + + + + + + +<h1>6 – <a name="6">Standard Libraries</a></h1> + +<p> +The standard Lua libraries provide useful functions +that are implemented directly through the C API. +Some of these functions provide essential services to the language +(e.g., <a href="#pdf-type"><code>type</code></a> and <a href="#pdf-getmetatable"><code>getmetatable</code></a>); +others provide access to "outside" services (e.g., I/O); +and others could be implemented in Lua itself, +but are quite useful or have critical performance requirements that +deserve an implementation in C (e.g., <a href="#pdf-table.sort"><code>table.sort</code></a>). + + +<p> +All libraries are implemented through the official C API +and are provided as separate C modules. +Currently, Lua has the following standard libraries: + +<ul> + +<li>basic library (<a href="#6.1">§6.1</a>);</li> + +<li>coroutine library (<a href="#6.2">§6.2</a>);</li> + +<li>package library (<a href="#6.3">§6.3</a>);</li> + +<li>string manipulation (<a href="#6.4">§6.4</a>);</li> + +<li>basic UTF-8 support (<a href="#6.5">§6.5</a>);</li> + +<li>table manipulation (<a href="#6.6">§6.6</a>);</li> + +<li>mathematical functions (<a href="#6.7">§6.7</a>) (sin, log, etc.);</li> + +<li>input and output (<a href="#6.8">§6.8</a>);</li> + +<li>operating system facilities (<a href="#6.9">§6.9</a>);</li> + +<li>debug facilities (<a href="#6.10">§6.10</a>).</li> + +</ul><p> +Except for the basic and the package libraries, +each library provides all its functions as fields of a global table +or as methods of its objects. + + +<p> +To have access to these libraries, +the C host program should call the <a href="#luaL_openlibs"><code>luaL_openlibs</code></a> function, +which opens all standard libraries. +Alternatively, +the host program can open them individually by using +<a href="#luaL_requiref"><code>luaL_requiref</code></a> to call +<a name="pdf-luaopen_base"><code>luaopen_base</code></a> (for the basic library), +<a name="pdf-luaopen_package"><code>luaopen_package</code></a> (for the package library), +<a name="pdf-luaopen_coroutine"><code>luaopen_coroutine</code></a> (for the coroutine library), +<a name="pdf-luaopen_string"><code>luaopen_string</code></a> (for the string library), +<a name="pdf-luaopen_utf8"><code>luaopen_utf8</code></a> (for the UTF8 library), +<a name="pdf-luaopen_table"><code>luaopen_table</code></a> (for the table library), +<a name="pdf-luaopen_math"><code>luaopen_math</code></a> (for the mathematical library), +<a name="pdf-luaopen_io"><code>luaopen_io</code></a> (for the I/O library), +<a name="pdf-luaopen_os"><code>luaopen_os</code></a> (for the operating system library), +and <a name="pdf-luaopen_debug"><code>luaopen_debug</code></a> (for the debug library). +These functions are declared in <a name="pdf-lualib.h"><code>lualib.h</code></a>. + + + +<h2>6.1 – <a name="6.1">Basic Functions</a></h2> + +<p> +The basic library provides core functions to Lua. +If you do not include this library in your application, +you should check carefully whether you need to provide +implementations for some of its facilities. + + +<p> +<hr><h3><a name="pdf-assert"><code>assert (v [, message])</code></a></h3> + + +<p> +Calls <a href="#pdf-error"><code>error</code></a> if +the value of its argument <code>v</code> is false (i.e., <b>nil</b> or <b>false</b>); +otherwise, returns all its arguments. +In case of error, +<code>message</code> is the error object; +when absent, it defaults to "<code>assertion failed!</code>" + + + + +<p> +<hr><h3><a name="pdf-collectgarbage"><code>collectgarbage ([opt [, arg]])</code></a></h3> + + +<p> +This function is a generic interface to the garbage collector. +It performs different functions according to its first argument, <code>opt</code>: + +<ul> + +<li><b>"<code>collect</code>": </b> +performs a full garbage-collection cycle. +This is the default option. +</li> + +<li><b>"<code>stop</code>": </b> +stops automatic execution of the garbage collector. +The collector will run only when explicitly invoked, +until a call to restart it. +</li> + +<li><b>"<code>restart</code>": </b> +restarts automatic execution of the garbage collector. +</li> + +<li><b>"<code>count</code>": </b> +returns the total memory in use by Lua in Kbytes. +The value has a fractional part, +so that it multiplied by 1024 +gives the exact number of bytes in use by Lua +(except for overflows). +</li> + +<li><b>"<code>step</code>": </b> +performs a garbage-collection step. +The step "size" is controlled by <code>arg</code>. +With a zero value, +the collector will perform one basic (indivisible) step. +For non-zero values, +the collector will perform as if that amount of memory +(in KBytes) had been allocated by Lua. +Returns <b>true</b> if the step finished a collection cycle. +</li> + +<li><b>"<code>setpause</code>": </b> +sets <code>arg</code> as the new value for the <em>pause</em> of +the collector (see <a href="#2.5">§2.5</a>). +Returns the previous value for <em>pause</em>. +</li> + +<li><b>"<code>setstepmul</code>": </b> +sets <code>arg</code> as the new value for the <em>step multiplier</em> of +the collector (see <a href="#2.5">§2.5</a>). +Returns the previous value for <em>step</em>. +</li> + +<li><b>"<code>isrunning</code>": </b> +returns a boolean that tells whether the collector is running +(i.e., not stopped). +</li> + +</ul> + + + +<p> +<hr><h3><a name="pdf-dofile"><code>dofile ([filename])</code></a></h3> +Opens the named file and executes its contents as a Lua chunk. +When called without arguments, +<code>dofile</code> executes the contents of the standard input (<code>stdin</code>). +Returns all values returned by the chunk. +In case of errors, <code>dofile</code> propagates the error +to its caller (that is, <code>dofile</code> does not run in protected mode). + + + + +<p> +<hr><h3><a name="pdf-error"><code>error (message [, level])</code></a></h3> +Terminates the last protected function called +and returns <code>message</code> as the error object. +Function <code>error</code> never returns. + + +<p> +Usually, <code>error</code> adds some information about the error position +at the beginning of the message, if the message is a string. +The <code>level</code> argument specifies how to get the error position. +With level 1 (the default), the error position is where the +<code>error</code> function was called. +Level 2 points the error to where the function +that called <code>error</code> was called; and so on. +Passing a level 0 avoids the addition of error position information +to the message. + + + + +<p> +<hr><h3><a name="pdf-_G"><code>_G</code></a></h3> +A global variable (not a function) that +holds the global environment (see <a href="#2.2">§2.2</a>). +Lua itself does not use this variable; +changing its value does not affect any environment, +nor vice versa. + + + + +<p> +<hr><h3><a name="pdf-getmetatable"><code>getmetatable (object)</code></a></h3> + + +<p> +If <code>object</code> does not have a metatable, returns <b>nil</b>. +Otherwise, +if the object's metatable has a <code>__metatable</code> field, +returns the associated value. +Otherwise, returns the metatable of the given object. + + + + +<p> +<hr><h3><a name="pdf-ipairs"><code>ipairs (t)</code></a></h3> + + +<p> +Returns three values (an iterator function, the table <code>t</code>, and 0) +so that the construction + +<pre> + for i,v in ipairs(t) do <em>body</em> end +</pre><p> +will iterate over the key–value pairs +(<code>1,t[1]</code>), (<code>2,t[2]</code>), ..., +up to the first nil value. + + + + +<p> +<hr><h3><a name="pdf-load"><code>load (chunk [, chunkname [, mode [, env]]])</code></a></h3> + + +<p> +Loads a chunk. + + +<p> +If <code>chunk</code> is a string, the chunk is this string. +If <code>chunk</code> is a function, +<code>load</code> calls it repeatedly to get the chunk pieces. +Each call to <code>chunk</code> must return a string that concatenates +with previous results. +A return of an empty string, <b>nil</b>, or no value signals the end of the chunk. + + +<p> +If there are no syntactic errors, +returns the compiled chunk as a function; +otherwise, returns <b>nil</b> plus the error message. + + +<p> +If the resulting function has upvalues, +the first upvalue is set to the value of <code>env</code>, +if that parameter is given, +or to the value of the global environment. +Other upvalues are initialized with <b>nil</b>. +(When you load a main chunk, +the resulting function will always have exactly one upvalue, +the <code>_ENV</code> variable (see <a href="#2.2">§2.2</a>). +However, +when you load a binary chunk created from a function (see <a href="#pdf-string.dump"><code>string.dump</code></a>), +the resulting function can have an arbitrary number of upvalues.) +All upvalues are fresh, that is, +they are not shared with any other function. + + +<p> +<code>chunkname</code> is used as the name of the chunk for error messages +and debug information (see <a href="#4.9">§4.9</a>). +When absent, +it defaults to <code>chunk</code>, if <code>chunk</code> is a string, +or to "<code>=(load)</code>" otherwise. + + +<p> +The string <code>mode</code> controls whether the chunk can be text or binary +(that is, a precompiled chunk). +It may be the string "<code>b</code>" (only binary chunks), +"<code>t</code>" (only text chunks), +or "<code>bt</code>" (both binary and text). +The default is "<code>bt</code>". + + +<p> +Lua does not check the consistency of binary chunks. +Maliciously crafted binary chunks can crash +the interpreter. + + + + +<p> +<hr><h3><a name="pdf-loadfile"><code>loadfile ([filename [, mode [, env]]])</code></a></h3> + + +<p> +Similar to <a href="#pdf-load"><code>load</code></a>, +but gets the chunk from file <code>filename</code> +or from the standard input, +if no file name is given. + + + + +<p> +<hr><h3><a name="pdf-next"><code>next (table [, index])</code></a></h3> + + +<p> +Allows a program to traverse all fields of a table. +Its first argument is a table and its second argument +is an index in this table. +<code>next</code> returns the next index of the table +and its associated value. +When called with <b>nil</b> as its second argument, +<code>next</code> returns an initial index +and its associated value. +When called with the last index, +or with <b>nil</b> in an empty table, +<code>next</code> returns <b>nil</b>. +If the second argument is absent, then it is interpreted as <b>nil</b>. +In particular, +you can use <code>next(t)</code> to check whether a table is empty. + + +<p> +The order in which the indices are enumerated is not specified, +<em>even for numeric indices</em>. +(To traverse a table in numerical order, +use a numerical <b>for</b>.) + + +<p> +The behavior of <code>next</code> is undefined if, +during the traversal, +you assign any value to a non-existent field in the table. +You may however modify existing fields. +In particular, you may clear existing fields. + + + + +<p> +<hr><h3><a name="pdf-pairs"><code>pairs (t)</code></a></h3> + + +<p> +If <code>t</code> has a metamethod <code>__pairs</code>, +calls it with <code>t</code> as argument and returns the first three +results from the call. + + +<p> +Otherwise, +returns three values: the <a href="#pdf-next"><code>next</code></a> function, the table <code>t</code>, and <b>nil</b>, +so that the construction + +<pre> + for k,v in pairs(t) do <em>body</em> end +</pre><p> +will iterate over all key–value pairs of table <code>t</code>. + + +<p> +See function <a href="#pdf-next"><code>next</code></a> for the caveats of modifying +the table during its traversal. + + + + +<p> +<hr><h3><a name="pdf-pcall"><code>pcall (f [, arg1, ···])</code></a></h3> + + +<p> +Calls function <code>f</code> with +the given arguments in <em>protected mode</em>. +This means that any error inside <code>f</code> is not propagated; +instead, <code>pcall</code> catches the error +and returns a status code. +Its first result is the status code (a boolean), +which is true if the call succeeds without errors. +In such case, <code>pcall</code> also returns all results from the call, +after this first result. +In case of any error, <code>pcall</code> returns <b>false</b> plus the error message. + + + + +<p> +<hr><h3><a name="pdf-print"><code>print (···)</code></a></h3> +Receives any number of arguments +and prints their values to <code>stdout</code>, +using the <a href="#pdf-tostring"><code>tostring</code></a> function to convert each argument to a string. +<code>print</code> is not intended for formatted output, +but only as a quick way to show a value, +for instance for debugging. +For complete control over the output, +use <a href="#pdf-string.format"><code>string.format</code></a> and <a href="#pdf-io.write"><code>io.write</code></a>. + + + + +<p> +<hr><h3><a name="pdf-rawequal"><code>rawequal (v1, v2)</code></a></h3> +Checks whether <code>v1</code> is equal to <code>v2</code>, +without invoking the <code>__eq</code> metamethod. +Returns a boolean. + + + + +<p> +<hr><h3><a name="pdf-rawget"><code>rawget (table, index)</code></a></h3> +Gets the real value of <code>table[index]</code>, +without invoking the <code>__index</code> metamethod. +<code>table</code> must be a table; +<code>index</code> may be any value. + + + + +<p> +<hr><h3><a name="pdf-rawlen"><code>rawlen (v)</code></a></h3> +Returns the length of the object <code>v</code>, +which must be a table or a string, +without invoking the <code>__len</code> metamethod. +Returns an integer. + + + + +<p> +<hr><h3><a name="pdf-rawset"><code>rawset (table, index, value)</code></a></h3> +Sets the real value of <code>table[index]</code> to <code>value</code>, +without invoking the <code>__newindex</code> metamethod. +<code>table</code> must be a table, +<code>index</code> any value different from <b>nil</b> and NaN, +and <code>value</code> any Lua value. + + +<p> +This function returns <code>table</code>. + + + + +<p> +<hr><h3><a name="pdf-select"><code>select (index, ···)</code></a></h3> + + +<p> +If <code>index</code> is a number, +returns all arguments after argument number <code>index</code>; +a negative number indexes from the end (-1 is the last argument). +Otherwise, <code>index</code> must be the string <code>"#"</code>, +and <code>select</code> returns the total number of extra arguments it received. + + + + +<p> +<hr><h3><a name="pdf-setmetatable"><code>setmetatable (table, metatable)</code></a></h3> + + +<p> +Sets the metatable for the given table. +(To change the metatable of other types from Lua code, +you must use the debug library (<a href="#6.10">§6.10</a>).) +If <code>metatable</code> is <b>nil</b>, +removes the metatable of the given table. +If the original metatable has a <code>__metatable</code> field, +raises an error. + + +<p> +This function returns <code>table</code>. + + + + +<p> +<hr><h3><a name="pdf-tonumber"><code>tonumber (e [, base])</code></a></h3> + + +<p> +When called with no <code>base</code>, +<code>tonumber</code> tries to convert its argument to a number. +If the argument is already a number or +a string convertible to a number, +then <code>tonumber</code> returns this number; +otherwise, it returns <b>nil</b>. + + +<p> +The conversion of strings can result in integers or floats, +according to the lexical conventions of Lua (see <a href="#3.1">§3.1</a>). +(The string may have leading and trailing spaces and a sign.) + + +<p> +When called with <code>base</code>, +then <code>e</code> must be a string to be interpreted as +an integer numeral in that base. +The base may be any integer between 2 and 36, inclusive. +In bases above 10, the letter '<code>A</code>' (in either upper or lower case) +represents 10, '<code>B</code>' represents 11, and so forth, +with '<code>Z</code>' representing 35. +If the string <code>e</code> is not a valid numeral in the given base, +the function returns <b>nil</b>. + + + + +<p> +<hr><h3><a name="pdf-tostring"><code>tostring (v)</code></a></h3> +Receives a value of any type and +converts it to a string in a human-readable format. +(For complete control of how numbers are converted, +use <a href="#pdf-string.format"><code>string.format</code></a>.) + + +<p> +If the metatable of <code>v</code> has a <code>__tostring</code> field, +then <code>tostring</code> calls the corresponding value +with <code>v</code> as argument, +and uses the result of the call as its result. + + + + +<p> +<hr><h3><a name="pdf-type"><code>type (v)</code></a></h3> +Returns the type of its only argument, coded as a string. +The possible results of this function are +"<code>nil</code>" (a string, not the value <b>nil</b>), +"<code>number</code>", +"<code>string</code>", +"<code>boolean</code>", +"<code>table</code>", +"<code>function</code>", +"<code>thread</code>", +and "<code>userdata</code>". + + + + +<p> +<hr><h3><a name="pdf-_VERSION"><code>_VERSION</code></a></h3> + + +<p> +A global variable (not a function) that +holds a string containing the running Lua version. +The current value of this variable is "<code>Lua 5.3</code>". + + + + +<p> +<hr><h3><a name="pdf-xpcall"><code>xpcall (f, msgh [, arg1, ···])</code></a></h3> + + +<p> +This function is similar to <a href="#pdf-pcall"><code>pcall</code></a>, +except that it sets a new message handler <code>msgh</code>. + + + + + + + +<h2>6.2 – <a name="6.2">Coroutine Manipulation</a></h2> + +<p> +This library comprises the operations to manipulate coroutines, +which come inside the table <a name="pdf-coroutine"><code>coroutine</code></a>. +See <a href="#2.6">§2.6</a> for a general description of coroutines. + + +<p> +<hr><h3><a name="pdf-coroutine.create"><code>coroutine.create (f)</code></a></h3> + + +<p> +Creates a new coroutine, with body <code>f</code>. +<code>f</code> must be a function. +Returns this new coroutine, +an object with type <code>"thread"</code>. + + + + +<p> +<hr><h3><a name="pdf-coroutine.isyieldable"><code>coroutine.isyieldable ()</code></a></h3> + + +<p> +Returns true when the running coroutine can yield. + + +<p> +A running coroutine is yieldable if it is not the main thread and +it is not inside a non-yieldable C function. + + + + +<p> +<hr><h3><a name="pdf-coroutine.resume"><code>coroutine.resume (co [, val1, ···])</code></a></h3> + + +<p> +Starts or continues the execution of coroutine <code>co</code>. +The first time you resume a coroutine, +it starts running its body. +The values <code>val1</code>, ... are passed +as the arguments to the body function. +If the coroutine has yielded, +<code>resume</code> restarts it; +the values <code>val1</code>, ... are passed +as the results from the yield. + + +<p> +If the coroutine runs without any errors, +<code>resume</code> returns <b>true</b> plus any values passed to <code>yield</code> +(when the coroutine yields) or any values returned by the body function +(when the coroutine terminates). +If there is any error, +<code>resume</code> returns <b>false</b> plus the error message. + + + + +<p> +<hr><h3><a name="pdf-coroutine.running"><code>coroutine.running ()</code></a></h3> + + +<p> +Returns the running coroutine plus a boolean, +true when the running coroutine is the main one. + + + + +<p> +<hr><h3><a name="pdf-coroutine.status"><code>coroutine.status (co)</code></a></h3> + + +<p> +Returns the status of coroutine <code>co</code>, as a string: +<code>"running"</code>, +if the coroutine is running (that is, it called <code>status</code>); +<code>"suspended"</code>, if the coroutine is suspended in a call to <code>yield</code>, +or if it has not started running yet; +<code>"normal"</code> if the coroutine is active but not running +(that is, it has resumed another coroutine); +and <code>"dead"</code> if the coroutine has finished its body function, +or if it has stopped with an error. + + + + +<p> +<hr><h3><a name="pdf-coroutine.wrap"><code>coroutine.wrap (f)</code></a></h3> + + +<p> +Creates a new coroutine, with body <code>f</code>. +<code>f</code> must be a function. +Returns a function that resumes the coroutine each time it is called. +Any arguments passed to the function behave as the +extra arguments to <code>resume</code>. +Returns the same values returned by <code>resume</code>, +except the first boolean. +In case of error, propagates the error. + + + + +<p> +<hr><h3><a name="pdf-coroutine.yield"><code>coroutine.yield (···)</code></a></h3> + + +<p> +Suspends the execution of the calling coroutine. +Any arguments to <code>yield</code> are passed as extra results to <code>resume</code>. + + + + + + + +<h2>6.3 – <a name="6.3">Modules</a></h2> + +<p> +The package library provides basic +facilities for loading modules in Lua. +It exports one function directly in the global environment: +<a href="#pdf-require"><code>require</code></a>. +Everything else is exported in a table <a name="pdf-package"><code>package</code></a>. + + +<p> +<hr><h3><a name="pdf-require"><code>require (modname)</code></a></h3> + + +<p> +Loads the given module. +The function starts by looking into the <a href="#pdf-package.loaded"><code>package.loaded</code></a> table +to determine whether <code>modname</code> is already loaded. +If it is, then <code>require</code> returns the value stored +at <code>package.loaded[modname]</code>. +Otherwise, it tries to find a <em>loader</em> for the module. + + +<p> +To find a loader, +<code>require</code> is guided by the <a href="#pdf-package.searchers"><code>package.searchers</code></a> sequence. +By changing this sequence, +we can change how <code>require</code> looks for a module. +The following explanation is based on the default configuration +for <a href="#pdf-package.searchers"><code>package.searchers</code></a>. + + +<p> +First <code>require</code> queries <code>package.preload[modname]</code>. +If it has a value, +this value (which must be a function) is the loader. +Otherwise <code>require</code> searches for a Lua loader using the +path stored in <a href="#pdf-package.path"><code>package.path</code></a>. +If that also fails, it searches for a C loader using the +path stored in <a href="#pdf-package.cpath"><code>package.cpath</code></a>. +If that also fails, +it tries an <em>all-in-one</em> loader (see <a href="#pdf-package.searchers"><code>package.searchers</code></a>). + + +<p> +Once a loader is found, +<code>require</code> calls the loader with two arguments: +<code>modname</code> and an extra value dependent on how it got the loader. +(If the loader came from a file, +this extra value is the file name.) +If the loader returns any non-nil value, +<code>require</code> assigns the returned value to <code>package.loaded[modname]</code>. +If the loader does not return a non-nil value and +has not assigned any value to <code>package.loaded[modname]</code>, +then <code>require</code> assigns <b>true</b> to this entry. +In any case, <code>require</code> returns the +final value of <code>package.loaded[modname]</code>. + + +<p> +If there is any error loading or running the module, +or if it cannot find any loader for the module, +then <code>require</code> raises an error. + + + + +<p> +<hr><h3><a name="pdf-package.config"><code>package.config</code></a></h3> + + +<p> +A string describing some compile-time configurations for packages. +This string is a sequence of lines: + +<ul> + +<li>The first line is the directory separator string. +Default is '<code>\</code>' for Windows and '<code>/</code>' for all other systems.</li> + +<li>The second line is the character that separates templates in a path. +Default is '<code>;</code>'.</li> + +<li>The third line is the string that marks the +substitution points in a template. +Default is '<code>?</code>'.</li> + +<li>The fourth line is a string that, in a path in Windows, +is replaced by the executable's directory. +Default is '<code>!</code>'.</li> + +<li>The fifth line is a mark to ignore all text after it +when building the <code>luaopen_</code> function name. +Default is '<code>-</code>'.</li> + +</ul> + + + +<p> +<hr><h3><a name="pdf-package.cpath"><code>package.cpath</code></a></h3> + + +<p> +The path used by <a href="#pdf-require"><code>require</code></a> to search for a C loader. + + +<p> +Lua initializes the C path <a href="#pdf-package.cpath"><code>package.cpath</code></a> in the same way +it initializes the Lua path <a href="#pdf-package.path"><code>package.path</code></a>, +using the environment variable <a name="pdf-LUA_CPATH_5_3"><code>LUA_CPATH_5_3</code></a>, +or the environment variable <a name="pdf-LUA_CPATH"><code>LUA_CPATH</code></a>, +or a default path defined in <code>luaconf.h</code>. + + + + +<p> +<hr><h3><a name="pdf-package.loaded"><code>package.loaded</code></a></h3> + + +<p> +A table used by <a href="#pdf-require"><code>require</code></a> to control which +modules are already loaded. +When you require a module <code>modname</code> and +<code>package.loaded[modname]</code> is not false, +<a href="#pdf-require"><code>require</code></a> simply returns the value stored there. + + +<p> +This variable is only a reference to the real table; +assignments to this variable do not change the +table used by <a href="#pdf-require"><code>require</code></a>. + + + + +<p> +<hr><h3><a name="pdf-package.loadlib"><code>package.loadlib (libname, funcname)</code></a></h3> + + +<p> +Dynamically links the host program with the C library <code>libname</code>. + + +<p> +If <code>funcname</code> is "<code>*</code>", +then it only links with the library, +making the symbols exported by the library +available to other dynamically linked libraries. +Otherwise, +it looks for a function <code>funcname</code> inside the library +and returns this function as a C function. +So, <code>funcname</code> must follow the <a href="#lua_CFunction"><code>lua_CFunction</code></a> prototype +(see <a href="#lua_CFunction"><code>lua_CFunction</code></a>). + + +<p> +This is a low-level function. +It completely bypasses the package and module system. +Unlike <a href="#pdf-require"><code>require</code></a>, +it does not perform any path searching and +does not automatically adds extensions. +<code>libname</code> must be the complete file name of the C library, +including if necessary a path and an extension. +<code>funcname</code> must be the exact name exported by the C library +(which may depend on the C compiler and linker used). + + +<p> +This function is not supported by Standard C. +As such, it is only available on some platforms +(Windows, Linux, Mac OS X, Solaris, BSD, +plus other Unix systems that support the <code>dlfcn</code> standard). + + + + +<p> +<hr><h3><a name="pdf-package.path"><code>package.path</code></a></h3> + + +<p> +The path used by <a href="#pdf-require"><code>require</code></a> to search for a Lua loader. + + +<p> +At start-up, Lua initializes this variable with +the value of the environment variable <a name="pdf-LUA_PATH_5_3"><code>LUA_PATH_5_3</code></a> or +the environment variable <a name="pdf-LUA_PATH"><code>LUA_PATH</code></a> or +with a default path defined in <code>luaconf.h</code>, +if those environment variables are not defined. +Any "<code>;;</code>" in the value of the environment variable +is replaced by the default path. + + + + +<p> +<hr><h3><a name="pdf-package.preload"><code>package.preload</code></a></h3> + + +<p> +A table to store loaders for specific modules +(see <a href="#pdf-require"><code>require</code></a>). + + +<p> +This variable is only a reference to the real table; +assignments to this variable do not change the +table used by <a href="#pdf-require"><code>require</code></a>. + + + + +<p> +<hr><h3><a name="pdf-package.searchers"><code>package.searchers</code></a></h3> + + +<p> +A table used by <a href="#pdf-require"><code>require</code></a> to control how to load modules. + + +<p> +Each entry in this table is a <em>searcher function</em>. +When looking for a module, +<a href="#pdf-require"><code>require</code></a> calls each of these searchers in ascending order, +with the module name (the argument given to <a href="#pdf-require"><code>require</code></a>) as its +sole parameter. +The function can return another function (the module <em>loader</em>) +plus an extra value that will be passed to that loader, +or a string explaining why it did not find that module +(or <b>nil</b> if it has nothing to say). + + +<p> +Lua initializes this table with four searcher functions. + + +<p> +The first searcher simply looks for a loader in the +<a href="#pdf-package.preload"><code>package.preload</code></a> table. + + +<p> +The second searcher looks for a loader as a Lua library, +using the path stored at <a href="#pdf-package.path"><code>package.path</code></a>. +The search is done as described in function <a href="#pdf-package.searchpath"><code>package.searchpath</code></a>. + + +<p> +The third searcher looks for a loader as a C library, +using the path given by the variable <a href="#pdf-package.cpath"><code>package.cpath</code></a>. +Again, +the search is done as described in function <a href="#pdf-package.searchpath"><code>package.searchpath</code></a>. +For instance, +if the C path is the string + +<pre> + "./?.so;./?.dll;/usr/local/?/init.so" +</pre><p> +the searcher for module <code>foo</code> +will try to open the files <code>./foo.so</code>, <code>./foo.dll</code>, +and <code>/usr/local/foo/init.so</code>, in that order. +Once it finds a C library, +this searcher first uses a dynamic link facility to link the +application with the library. +Then it tries to find a C function inside the library to +be used as the loader. +The name of this C function is the string "<code>luaopen_</code>" +concatenated with a copy of the module name where each dot +is replaced by an underscore. +Moreover, if the module name has a hyphen, +its suffix after (and including) the first hyphen is removed. +For instance, if the module name is <code>a.b.c-v2.1</code>, +the function name will be <code>luaopen_a_b_c</code>. + + +<p> +The fourth searcher tries an <em>all-in-one loader</em>. +It searches the C path for a library for +the root name of the given module. +For instance, when requiring <code>a.b.c</code>, +it will search for a C library for <code>a</code>. +If found, it looks into it for an open function for +the submodule; +in our example, that would be <code>luaopen_a_b_c</code>. +With this facility, a package can pack several C submodules +into one single library, +with each submodule keeping its original open function. + + +<p> +All searchers except the first one (preload) return as the extra value +the file name where the module was found, +as returned by <a href="#pdf-package.searchpath"><code>package.searchpath</code></a>. +The first searcher returns no extra value. + + + + +<p> +<hr><h3><a name="pdf-package.searchpath"><code>package.searchpath (name, path [, sep [, rep]])</code></a></h3> + + +<p> +Searches for the given <code>name</code> in the given <code>path</code>. + + +<p> +A path is a string containing a sequence of +<em>templates</em> separated by semicolons. +For each template, +the function replaces each interrogation mark (if any) +in the template with a copy of <code>name</code> +wherein all occurrences of <code>sep</code> +(a dot, by default) +were replaced by <code>rep</code> +(the system's directory separator, by default), +and then tries to open the resulting file name. + + +<p> +For instance, if the path is the string + +<pre> + "./?.lua;./?.lc;/usr/local/?/init.lua" +</pre><p> +the search for the name <code>foo.a</code> +will try to open the files +<code>./foo/a.lua</code>, <code>./foo/a.lc</code>, and +<code>/usr/local/foo/a/init.lua</code>, in that order. + + +<p> +Returns the resulting name of the first file that it can +open in read mode (after closing the file), +or <b>nil</b> plus an error message if none succeeds. +(This error message lists all file names it tried to open.) + + + + + + + +<h2>6.4 – <a name="6.4">String Manipulation</a></h2> + +<p> +This library provides generic functions for string manipulation, +such as finding and extracting substrings, and pattern matching. +When indexing a string in Lua, the first character is at position 1 +(not at 0, as in C). +Indices are allowed to be negative and are interpreted as indexing backwards, +from the end of the string. +Thus, the last character is at position -1, and so on. + + +<p> +The string library provides all its functions inside the table +<a name="pdf-string"><code>string</code></a>. +It also sets a metatable for strings +where the <code>__index</code> field points to the <code>string</code> table. +Therefore, you can use the string functions in object-oriented style. +For instance, <code>string.byte(s,i)</code> +can be written as <code>s:byte(i)</code>. + + +<p> +The string library assumes one-byte character encodings. + + +<p> +<hr><h3><a name="pdf-string.byte"><code>string.byte (s [, i [, j]])</code></a></h3> +Returns the internal numeric codes of the characters <code>s[i]</code>, +<code>s[i+1]</code>, ..., <code>s[j]</code>. +The default value for <code>i</code> is 1; +the default value for <code>j</code> is <code>i</code>. +These indices are corrected +following the same rules of function <a href="#pdf-string.sub"><code>string.sub</code></a>. + + +<p> +Numeric codes are not necessarily portable across platforms. + + + + +<p> +<hr><h3><a name="pdf-string.char"><code>string.char (···)</code></a></h3> +Receives zero or more integers. +Returns a string with length equal to the number of arguments, +in which each character has the internal numeric code equal +to its corresponding argument. + + +<p> +Numeric codes are not necessarily portable across platforms. + + + + +<p> +<hr><h3><a name="pdf-string.dump"><code>string.dump (function [, strip])</code></a></h3> + + +<p> +Returns a string containing a binary representation +(a <em>binary chunk</em>) +of the given function, +so that a later <a href="#pdf-load"><code>load</code></a> on this string returns +a copy of the function (but with new upvalues). +If <code>strip</code> is a true value, +the binary representation may not include all debug information +about the function, +to save space. + + +<p> +Functions with upvalues have only their number of upvalues saved. +When (re)loaded, +those upvalues receive fresh instances containing <b>nil</b>. +(You can use the debug library to serialize +and reload the upvalues of a function +in a way adequate to your needs.) + + + + +<p> +<hr><h3><a name="pdf-string.find"><code>string.find (s, pattern [, init [, plain]])</code></a></h3> + + +<p> +Looks for the first match of +<code>pattern</code> (see <a href="#6.4.1">§6.4.1</a>) in the string <code>s</code>. +If it finds a match, then <code>find</code> returns the indices of <code>s</code> +where this occurrence starts and ends; +otherwise, it returns <b>nil</b>. +A third, optional numeric argument <code>init</code> specifies +where to start the search; +its default value is 1 and can be negative. +A value of <b>true</b> as a fourth, optional argument <code>plain</code> +turns off the pattern matching facilities, +so the function does a plain "find substring" operation, +with no characters in <code>pattern</code> being considered magic. +Note that if <code>plain</code> is given, then <code>init</code> must be given as well. + + +<p> +If the pattern has captures, +then in a successful match +the captured values are also returned, +after the two indices. + + + + +<p> +<hr><h3><a name="pdf-string.format"><code>string.format (formatstring, ···)</code></a></h3> + + +<p> +Returns a formatted version of its variable number of arguments +following the description given in its first argument (which must be a string). +The format string follows the same rules as the ISO C function <code>sprintf</code>. +The only differences are that the options/modifiers +<code>*</code>, <code>h</code>, <code>L</code>, <code>l</code>, <code>n</code>, +and <code>p</code> are not supported +and that there is an extra option, <code>q</code>. + + +<p> +The <code>q</code> option formats a string between double quotes, +using escape sequences when necessary to ensure that +it can safely be read back by the Lua interpreter. +For instance, the call + +<pre> + string.format('%q', 'a string with "quotes" and \n new line') +</pre><p> +may produce the string: + +<pre> + "a string with \"quotes\" and \ + new line" +</pre> + +<p> +Options +<code>A</code>, <code>a</code>, <code>E</code>, <code>e</code>, <code>f</code>, +<code>G</code>, and <code>g</code> all expect a number as argument. +Options <code>c</code>, <code>d</code>, +<code>i</code>, <code>o</code>, <code>u</code>, <code>X</code>, and <code>x</code> +expect an integer. +When Lua is compiled with a C89 compiler, +options <code>A</code> and <code>a</code> (hexadecimal floats) +do not support any modifier (flags, width, length). + + +<p> +Option <code>s</code> expects a string; +if its argument is not a string, +it is converted to one following the same rules of <a href="#pdf-tostring"><code>tostring</code></a>. +If the option has any modifier (flags, width, length), +the string argument should not contain embedded zeros. + + + + +<p> +<hr><h3><a name="pdf-string.gmatch"><code>string.gmatch (s, pattern)</code></a></h3> +Returns an iterator function that, +each time it is called, +returns the next captures from <code>pattern</code> (see <a href="#6.4.1">§6.4.1</a>) +over the string <code>s</code>. +If <code>pattern</code> specifies no captures, +then the whole match is produced in each call. + + +<p> +As an example, the following loop +will iterate over all the words from string <code>s</code>, +printing one per line: + +<pre> + s = "hello world from Lua" + for w in string.gmatch(s, "%a+") do + print(w) + end +</pre><p> +The next example collects all pairs <code>key=value</code> from the +given string into a table: + +<pre> + t = {} + s = "from=world, to=Lua" + for k, v in string.gmatch(s, "(%w+)=(%w+)") do + t[k] = v + end +</pre> + +<p> +For this function, a caret '<code>^</code>' at the start of a pattern does not +work as an anchor, as this would prevent the iteration. + + + + +<p> +<hr><h3><a name="pdf-string.gsub"><code>string.gsub (s, pattern, repl [, n])</code></a></h3> +Returns a copy of <code>s</code> +in which all (or the first <code>n</code>, if given) +occurrences of the <code>pattern</code> (see <a href="#6.4.1">§6.4.1</a>) have been +replaced by a replacement string specified by <code>repl</code>, +which can be a string, a table, or a function. +<code>gsub</code> also returns, as its second value, +the total number of matches that occurred. +The name <code>gsub</code> comes from <em>Global SUBstitution</em>. + + +<p> +If <code>repl</code> is a string, then its value is used for replacement. +The character <code>%</code> works as an escape character: +any sequence in <code>repl</code> of the form <code>%<em>d</em></code>, +with <em>d</em> between 1 and 9, +stands for the value of the <em>d</em>-th captured substring. +The sequence <code>%0</code> stands for the whole match. +The sequence <code>%%</code> stands for a single <code>%</code>. + + +<p> +If <code>repl</code> is a table, then the table is queried for every match, +using the first capture as the key. + + +<p> +If <code>repl</code> is a function, then this function is called every time a +match occurs, with all captured substrings passed as arguments, +in order. + + +<p> +In any case, +if the pattern specifies no captures, +then it behaves as if the whole pattern was inside a capture. + + +<p> +If the value returned by the table query or by the function call +is a string or a number, +then it is used as the replacement string; +otherwise, if it is <b>false</b> or <b>nil</b>, +then there is no replacement +(that is, the original match is kept in the string). + + +<p> +Here are some examples: + +<pre> + x = string.gsub("hello world", "(%w+)", "%1 %1") + --> x="hello hello world world" + + x = string.gsub("hello world", "%w+", "%0 %0", 1) + --> x="hello hello world" + + x = string.gsub("hello world from Lua", "(%w+)%s*(%w+)", "%2 %1") + --> x="world hello Lua from" + + x = string.gsub("home = $HOME, user = $USER", "%$(%w+)", os.getenv) + --> x="home = /home/roberto, user = roberto" + + x = string.gsub("4+5 = $return 4+5$", "%$(.-)%$", function (s) + return load(s)() + end) + --> x="4+5 = 9" + + local t = {name="lua", version="5.3"} + x = string.gsub("$name-$version.tar.gz", "%$(%w+)", t) + --> x="lua-5.3.tar.gz" +</pre> + + + +<p> +<hr><h3><a name="pdf-string.len"><code>string.len (s)</code></a></h3> +Receives a string and returns its length. +The empty string <code>""</code> has length 0. +Embedded zeros are counted, +so <code>"a\000bc\000"</code> has length 5. + + + + +<p> +<hr><h3><a name="pdf-string.lower"><code>string.lower (s)</code></a></h3> +Receives a string and returns a copy of this string with all +uppercase letters changed to lowercase. +All other characters are left unchanged. +The definition of what an uppercase letter is depends on the current locale. + + + + +<p> +<hr><h3><a name="pdf-string.match"><code>string.match (s, pattern [, init])</code></a></h3> +Looks for the first <em>match</em> of +<code>pattern</code> (see <a href="#6.4.1">§6.4.1</a>) in the string <code>s</code>. +If it finds one, then <code>match</code> returns +the captures from the pattern; +otherwise it returns <b>nil</b>. +If <code>pattern</code> specifies no captures, +then the whole match is returned. +A third, optional numeric argument <code>init</code> specifies +where to start the search; +its default value is 1 and can be negative. + + + + +<p> +<hr><h3><a name="pdf-string.pack"><code>string.pack (fmt, v1, v2, ···)</code></a></h3> + + +<p> +Returns a binary string containing the values <code>v1</code>, <code>v2</code>, etc. +packed (that is, serialized in binary form) +according to the format string <code>fmt</code> (see <a href="#6.4.2">§6.4.2</a>). + + + + +<p> +<hr><h3><a name="pdf-string.packsize"><code>string.packsize (fmt)</code></a></h3> + + +<p> +Returns the size of a string resulting from <a href="#pdf-string.pack"><code>string.pack</code></a> +with the given format. +The format string cannot have the variable-length options +'<code>s</code>' or '<code>z</code>' (see <a href="#6.4.2">§6.4.2</a>). + + + + +<p> +<hr><h3><a name="pdf-string.rep"><code>string.rep (s, n [, sep])</code></a></h3> +Returns a string that is the concatenation of <code>n</code> copies of +the string <code>s</code> separated by the string <code>sep</code>. +The default value for <code>sep</code> is the empty string +(that is, no separator). +Returns the empty string if <code>n</code> is not positive. + + +<p> +(Note that it is very easy to exhaust the memory of your machine +with a single call to this function.) + + + + +<p> +<hr><h3><a name="pdf-string.reverse"><code>string.reverse (s)</code></a></h3> +Returns a string that is the string <code>s</code> reversed. + + + + +<p> +<hr><h3><a name="pdf-string.sub"><code>string.sub (s, i [, j])</code></a></h3> +Returns the substring of <code>s</code> that +starts at <code>i</code> and continues until <code>j</code>; +<code>i</code> and <code>j</code> can be negative. +If <code>j</code> is absent, then it is assumed to be equal to -1 +(which is the same as the string length). +In particular, +the call <code>string.sub(s,1,j)</code> returns a prefix of <code>s</code> +with length <code>j</code>, +and <code>string.sub(s, -i)</code> (for a positive <code>i</code>) +returns a suffix of <code>s</code> +with length <code>i</code>. + + +<p> +If, after the translation of negative indices, +<code>i</code> is less than 1, +it is corrected to 1. +If <code>j</code> is greater than the string length, +it is corrected to that length. +If, after these corrections, +<code>i</code> is greater than <code>j</code>, +the function returns the empty string. + + + + +<p> +<hr><h3><a name="pdf-string.unpack"><code>string.unpack (fmt, s [, pos])</code></a></h3> + + +<p> +Returns the values packed in string <code>s</code> (see <a href="#pdf-string.pack"><code>string.pack</code></a>) +according to the format string <code>fmt</code> (see <a href="#6.4.2">§6.4.2</a>). +An optional <code>pos</code> marks where +to start reading in <code>s</code> (default is 1). +After the read values, +this function also returns the index of the first unread byte in <code>s</code>. + + + + +<p> +<hr><h3><a name="pdf-string.upper"><code>string.upper (s)</code></a></h3> +Receives a string and returns a copy of this string with all +lowercase letters changed to uppercase. +All other characters are left unchanged. +The definition of what a lowercase letter is depends on the current locale. + + + + + +<h3>6.4.1 – <a name="6.4.1">Patterns</a></h3> + +<p> +Patterns in Lua are described by regular strings, +which are interpreted as patterns by the pattern-matching functions +<a href="#pdf-string.find"><code>string.find</code></a>, +<a href="#pdf-string.gmatch"><code>string.gmatch</code></a>, +<a href="#pdf-string.gsub"><code>string.gsub</code></a>, +and <a href="#pdf-string.match"><code>string.match</code></a>. +This section describes the syntax and the meaning +(that is, what they match) of these strings. + + + +<h4>Character Class:</h4><p> +A <em>character class</em> is used to represent a set of characters. +The following combinations are allowed in describing a character class: + +<ul> + +<li><b><em>x</em>: </b> +(where <em>x</em> is not one of the <em>magic characters</em> +<code>^$()%.[]*+-?</code>) +represents the character <em>x</em> itself. +</li> + +<li><b><code>.</code>: </b> (a dot) represents all characters.</li> + +<li><b><code>%a</code>: </b> represents all letters.</li> + +<li><b><code>%c</code>: </b> represents all control characters.</li> + +<li><b><code>%d</code>: </b> represents all digits.</li> + +<li><b><code>%g</code>: </b> represents all printable characters except space.</li> + +<li><b><code>%l</code>: </b> represents all lowercase letters.</li> + +<li><b><code>%p</code>: </b> represents all punctuation characters.</li> + +<li><b><code>%s</code>: </b> represents all space characters.</li> + +<li><b><code>%u</code>: </b> represents all uppercase letters.</li> + +<li><b><code>%w</code>: </b> represents all alphanumeric characters.</li> + +<li><b><code>%x</code>: </b> represents all hexadecimal digits.</li> + +<li><b><code>%<em>x</em></code>: </b> (where <em>x</em> is any non-alphanumeric character) +represents the character <em>x</em>. +This is the standard way to escape the magic characters. +Any non-alphanumeric character +(including all punctuation characters, even the non-magical) +can be preceded by a '<code>%</code>' +when used to represent itself in a pattern. +</li> + +<li><b><code>[<em>set</em>]</code>: </b> +represents the class which is the union of all +characters in <em>set</em>. +A range of characters can be specified by +separating the end characters of the range, +in ascending order, with a '<code>-</code>'. +All classes <code>%</code><em>x</em> described above can also be used as +components in <em>set</em>. +All other characters in <em>set</em> represent themselves. +For example, <code>[%w_]</code> (or <code>[_%w]</code>) +represents all alphanumeric characters plus the underscore, +<code>[0-7]</code> represents the octal digits, +and <code>[0-7%l%-]</code> represents the octal digits plus +the lowercase letters plus the '<code>-</code>' character. + + +<p> +You can put a closing square bracket in a set +by positioning it as the first character in the set. +You can put a hyphen in a set +by positioning it as the first or the last character in the set. +(You can also use an escape for both cases.) + + +<p> +The interaction between ranges and classes is not defined. +Therefore, patterns like <code>[%a-z]</code> or <code>[a-%%]</code> +have no meaning. +</li> + +<li><b><code>[^<em>set</em>]</code>: </b> +represents the complement of <em>set</em>, +where <em>set</em> is interpreted as above. +</li> + +</ul><p> +For all classes represented by single letters (<code>%a</code>, <code>%c</code>, etc.), +the corresponding uppercase letter represents the complement of the class. +For instance, <code>%S</code> represents all non-space characters. + + +<p> +The definitions of letter, space, and other character groups +depend on the current locale. +In particular, the class <code>[a-z]</code> may not be equivalent to <code>%l</code>. + + + + + +<h4>Pattern Item:</h4><p> +A <em>pattern item</em> can be + +<ul> + +<li> +a single character class, +which matches any single character in the class; +</li> + +<li> +a single character class followed by '<code>*</code>', +which matches zero or more repetitions of characters in the class. +These repetition items will always match the longest possible sequence; +</li> + +<li> +a single character class followed by '<code>+</code>', +which matches one or more repetitions of characters in the class. +These repetition items will always match the longest possible sequence; +</li> + +<li> +a single character class followed by '<code>-</code>', +which also matches zero or more repetitions of characters in the class. +Unlike '<code>*</code>', +these repetition items will always match the shortest possible sequence; +</li> + +<li> +a single character class followed by '<code>?</code>', +which matches zero or one occurrence of a character in the class. +It always matches one occurrence if possible; +</li> + +<li> +<code>%<em>n</em></code>, for <em>n</em> between 1 and 9; +such item matches a substring equal to the <em>n</em>-th captured string +(see below); +</li> + +<li> +<code>%b<em>xy</em></code>, where <em>x</em> and <em>y</em> are two distinct characters; +such item matches strings that start with <em>x</em>, end with <em>y</em>, +and where the <em>x</em> and <em>y</em> are <em>balanced</em>. +This means that, if one reads the string from left to right, +counting <em>+1</em> for an <em>x</em> and <em>-1</em> for a <em>y</em>, +the ending <em>y</em> is the first <em>y</em> where the count reaches 0. +For instance, the item <code>%b()</code> matches expressions with +balanced parentheses. +</li> + +<li> +<code>%f[<em>set</em>]</code>, a <em>frontier pattern</em>; +such item matches an empty string at any position such that +the next character belongs to <em>set</em> +and the previous character does not belong to <em>set</em>. +The set <em>set</em> is interpreted as previously described. +The beginning and the end of the subject are handled as if +they were the character '<code>\0</code>'. +</li> + +</ul> + + + + +<h4>Pattern:</h4><p> +A <em>pattern</em> is a sequence of pattern items. +A caret '<code>^</code>' at the beginning of a pattern anchors the match at the +beginning of the subject string. +A '<code>$</code>' at the end of a pattern anchors the match at the +end of the subject string. +At other positions, +'<code>^</code>' and '<code>$</code>' have no special meaning and represent themselves. + + + + + +<h4>Captures:</h4><p> +A pattern can contain sub-patterns enclosed in parentheses; +they describe <em>captures</em>. +When a match succeeds, the substrings of the subject string +that match captures are stored (<em>captured</em>) for future use. +Captures are numbered according to their left parentheses. +For instance, in the pattern <code>"(a*(.)%w(%s*))"</code>, +the part of the string matching <code>"a*(.)%w(%s*)"</code> is +stored as the first capture (and therefore has number 1); +the character matching "<code>.</code>" is captured with number 2, +and the part matching "<code>%s*</code>" has number 3. + + +<p> +As a special case, the empty capture <code>()</code> captures +the current string position (a number). +For instance, if we apply the pattern <code>"()aa()"</code> on the +string <code>"flaaap"</code>, there will be two captures: 3 and 5. + + + + + + + +<h3>6.4.2 – <a name="6.4.2">Format Strings for Pack and Unpack</a></h3> + +<p> +The first argument to <a href="#pdf-string.pack"><code>string.pack</code></a>, +<a href="#pdf-string.packsize"><code>string.packsize</code></a>, and <a href="#pdf-string.unpack"><code>string.unpack</code></a> +is a format string, +which describes the layout of the structure being created or read. + + +<p> +A format string is a sequence of conversion options. +The conversion options are as follows: + +<ul> +<li><b><code><</code>: </b>sets little endian</li> +<li><b><code>></code>: </b>sets big endian</li> +<li><b><code>=</code>: </b>sets native endian</li> +<li><b><code>![<em>n</em>]</code>: </b>sets maximum alignment to <code>n</code> +(default is native alignment)</li> +<li><b><code>b</code>: </b>a signed byte (<code>char</code>)</li> +<li><b><code>B</code>: </b>an unsigned byte (<code>char</code>)</li> +<li><b><code>h</code>: </b>a signed <code>short</code> (native size)</li> +<li><b><code>H</code>: </b>an unsigned <code>short</code> (native size)</li> +<li><b><code>l</code>: </b>a signed <code>long</code> (native size)</li> +<li><b><code>L</code>: </b>an unsigned <code>long</code> (native size)</li> +<li><b><code>j</code>: </b>a <code>lua_Integer</code></li> +<li><b><code>J</code>: </b>a <code>lua_Unsigned</code></li> +<li><b><code>T</code>: </b>a <code>size_t</code> (native size)</li> +<li><b><code>i[<em>n</em>]</code>: </b>a signed <code>int</code> with <code>n</code> bytes +(default is native size)</li> +<li><b><code>I[<em>n</em>]</code>: </b>an unsigned <code>int</code> with <code>n</code> bytes +(default is native size)</li> +<li><b><code>f</code>: </b>a <code>float</code> (native size)</li> +<li><b><code>d</code>: </b>a <code>double</code> (native size)</li> +<li><b><code>n</code>: </b>a <code>lua_Number</code></li> +<li><b><code>c<em>n</em></code>: </b>a fixed-sized string with <code>n</code> bytes</li> +<li><b><code>z</code>: </b>a zero-terminated string</li> +<li><b><code>s[<em>n</em>]</code>: </b>a string preceded by its length +coded as an unsigned integer with <code>n</code> bytes +(default is a <code>size_t</code>)</li> +<li><b><code>x</code>: </b>one byte of padding</li> +<li><b><code>X<em>op</em></code>: </b>an empty item that aligns +according to option <code>op</code> +(which is otherwise ignored)</li> +<li><b>'<code> </code>': </b>(empty space) ignored</li> +</ul><p> +(A "<code>[<em>n</em>]</code>" means an optional integral numeral.) +Except for padding, spaces, and configurations +(options "<code>xX <=>!</code>"), +each option corresponds to an argument (in <a href="#pdf-string.pack"><code>string.pack</code></a>) +or a result (in <a href="#pdf-string.unpack"><code>string.unpack</code></a>). + + +<p> +For options "<code>!<em>n</em></code>", "<code>s<em>n</em></code>", "<code>i<em>n</em></code>", and "<code>I<em>n</em></code>", +<code>n</code> can be any integer between 1 and 16. +All integral options check overflows; +<a href="#pdf-string.pack"><code>string.pack</code></a> checks whether the given value fits in the given size; +<a href="#pdf-string.unpack"><code>string.unpack</code></a> checks whether the read value fits in a Lua integer. + + +<p> +Any format string starts as if prefixed by "<code>!1=</code>", +that is, +with maximum alignment of 1 (no alignment) +and native endianness. + + +<p> +Alignment works as follows: +For each option, +the format gets extra padding until the data starts +at an offset that is a multiple of the minimum between the +option size and the maximum alignment; +this minimum must be a power of 2. +Options "<code>c</code>" and "<code>z</code>" are not aligned; +option "<code>s</code>" follows the alignment of its starting integer. + + +<p> +All padding is filled with zeros by <a href="#pdf-string.pack"><code>string.pack</code></a> +(and ignored by <a href="#pdf-string.unpack"><code>string.unpack</code></a>). + + + + + + + +<h2>6.5 – <a name="6.5">UTF-8 Support</a></h2> + +<p> +This library provides basic support for UTF-8 encoding. +It provides all its functions inside the table <a name="pdf-utf8"><code>utf8</code></a>. +This library does not provide any support for Unicode other +than the handling of the encoding. +Any operation that needs the meaning of a character, +such as character classification, is outside its scope. + + +<p> +Unless stated otherwise, +all functions that expect a byte position as a parameter +assume that the given position is either the start of a byte sequence +or one plus the length of the subject string. +As in the string library, +negative indices count from the end of the string. + + +<p> +<hr><h3><a name="pdf-utf8.char"><code>utf8.char (···)</code></a></h3> +Receives zero or more integers, +converts each one to its corresponding UTF-8 byte sequence +and returns a string with the concatenation of all these sequences. + + + + +<p> +<hr><h3><a name="pdf-utf8.charpattern"><code>utf8.charpattern</code></a></h3> +The pattern (a string, not a function) "<code>[\0-\x7F\xC2-\xF4][\x80-\xBF]*</code>" +(see <a href="#6.4.1">§6.4.1</a>), +which matches exactly one UTF-8 byte sequence, +assuming that the subject is a valid UTF-8 string. + + + + +<p> +<hr><h3><a name="pdf-utf8.codes"><code>utf8.codes (s)</code></a></h3> + + +<p> +Returns values so that the construction + +<pre> + for p, c in utf8.codes(s) do <em>body</em> end +</pre><p> +will iterate over all characters in string <code>s</code>, +with <code>p</code> being the position (in bytes) and <code>c</code> the code point +of each character. +It raises an error if it meets any invalid byte sequence. + + + + +<p> +<hr><h3><a name="pdf-utf8.codepoint"><code>utf8.codepoint (s [, i [, j]])</code></a></h3> +Returns the codepoints (as integers) from all characters in <code>s</code> +that start between byte position <code>i</code> and <code>j</code> (both included). +The default for <code>i</code> is 1 and for <code>j</code> is <code>i</code>. +It raises an error if it meets any invalid byte sequence. + + + + +<p> +<hr><h3><a name="pdf-utf8.len"><code>utf8.len (s [, i [, j]])</code></a></h3> +Returns the number of UTF-8 characters in string <code>s</code> +that start between positions <code>i</code> and <code>j</code> (both inclusive). +The default for <code>i</code> is 1 and for <code>j</code> is -1. +If it finds any invalid byte sequence, +returns a false value plus the position of the first invalid byte. + + + + +<p> +<hr><h3><a name="pdf-utf8.offset"><code>utf8.offset (s, n [, i])</code></a></h3> +Returns the position (in bytes) where the encoding of the +<code>n</code>-th character of <code>s</code> +(counting from position <code>i</code>) starts. +A negative <code>n</code> gets characters before position <code>i</code>. +The default for <code>i</code> is 1 when <code>n</code> is non-negative +and <code>#s + 1</code> otherwise, +so that <code>utf8.offset(s, -n)</code> gets the offset of the +<code>n</code>-th character from the end of the string. +If the specified character is neither in the subject +nor right after its end, +the function returns <b>nil</b>. + + +<p> +As a special case, +when <code>n</code> is 0 the function returns the start of the encoding +of the character that contains the <code>i</code>-th byte of <code>s</code>. + + +<p> +This function assumes that <code>s</code> is a valid UTF-8 string. + + + + + + + +<h2>6.6 – <a name="6.6">Table Manipulation</a></h2> + +<p> +This library provides generic functions for table manipulation. +It provides all its functions inside the table <a name="pdf-table"><code>table</code></a>. + + +<p> +Remember that, whenever an operation needs the length of a table, +all caveats about the length operator apply (see <a href="#3.4.7">§3.4.7</a>). +All functions ignore non-numeric keys +in the tables given as arguments. + + +<p> +<hr><h3><a name="pdf-table.concat"><code>table.concat (list [, sep [, i [, j]]])</code></a></h3> + + +<p> +Given a list where all elements are strings or numbers, +returns the string <code>list[i]..sep..list[i+1] ··· sep..list[j]</code>. +The default value for <code>sep</code> is the empty string, +the default for <code>i</code> is 1, +and the default for <code>j</code> is <code>#list</code>. +If <code>i</code> is greater than <code>j</code>, returns the empty string. + + + + +<p> +<hr><h3><a name="pdf-table.insert"><code>table.insert (list, [pos,] value)</code></a></h3> + + +<p> +Inserts element <code>value</code> at position <code>pos</code> in <code>list</code>, +shifting up the elements +<code>list[pos], list[pos+1], ···, list[#list]</code>. +The default value for <code>pos</code> is <code>#list+1</code>, +so that a call <code>table.insert(t,x)</code> inserts <code>x</code> at the end +of list <code>t</code>. + + + + +<p> +<hr><h3><a name="pdf-table.move"><code>table.move (a1, f, e, t [,a2])</code></a></h3> + + +<p> +Moves elements from table <code>a1</code> to table <code>a2</code>, +performing the equivalent to the following +multiple assignment: +<code>a2[t],··· = a1[f],···,a1[e]</code>. +The default for <code>a2</code> is <code>a1</code>. +The destination range can overlap with the source range. +The number of elements to be moved must fit in a Lua integer. + + +<p> +Returns the destination table <code>a2</code>. + + + + +<p> +<hr><h3><a name="pdf-table.pack"><code>table.pack (···)</code></a></h3> + + +<p> +Returns a new table with all arguments stored into keys 1, 2, etc. +and with a field "<code>n</code>" with the total number of arguments. +Note that the resulting table may not be a sequence. + + + + +<p> +<hr><h3><a name="pdf-table.remove"><code>table.remove (list [, pos])</code></a></h3> + + +<p> +Removes from <code>list</code> the element at position <code>pos</code>, +returning the value of the removed element. +When <code>pos</code> is an integer between 1 and <code>#list</code>, +it shifts down the elements +<code>list[pos+1], list[pos+2], ···, list[#list]</code> +and erases element <code>list[#list]</code>; +The index <code>pos</code> can also be 0 when <code>#list</code> is 0, +or <code>#list + 1</code>; +in those cases, the function erases the element <code>list[pos]</code>. + + +<p> +The default value for <code>pos</code> is <code>#list</code>, +so that a call <code>table.remove(l)</code> removes the last element +of list <code>l</code>. + + + + +<p> +<hr><h3><a name="pdf-table.sort"><code>table.sort (list [, comp])</code></a></h3> + + +<p> +Sorts list elements in a given order, <em>in-place</em>, +from <code>list[1]</code> to <code>list[#list]</code>. +If <code>comp</code> is given, +then it must be a function that receives two list elements +and returns true when the first element must come +before the second in the final order +(so that, after the sort, +<code>i < j</code> implies <code>not comp(list[j],list[i])</code>). +If <code>comp</code> is not given, +then the standard Lua operator <code><</code> is used instead. + + +<p> +Note that the <code>comp</code> function must define +a strict partial order over the elements in the list; +that is, it must be asymmetric and transitive. +Otherwise, no valid sort may be possible. + + +<p> +The sort algorithm is not stable: +elements considered equal by the given order +may have their relative positions changed by the sort. + + + + +<p> +<hr><h3><a name="pdf-table.unpack"><code>table.unpack (list [, i [, j]])</code></a></h3> + + +<p> +Returns the elements from the given list. +This function is equivalent to + +<pre> + return list[i], list[i+1], ···, list[j] +</pre><p> +By default, <code>i</code> is 1 and <code>j</code> is <code>#list</code>. + + + + + + + +<h2>6.7 – <a name="6.7">Mathematical Functions</a></h2> + +<p> +This library provides basic mathematical functions. +It provides all its functions and constants inside the table <a name="pdf-math"><code>math</code></a>. +Functions with the annotation "<code>integer/float</code>" give +integer results for integer arguments +and float results for float (or mixed) arguments. +Rounding functions +(<a href="#pdf-math.ceil"><code>math.ceil</code></a>, <a href="#pdf-math.floor"><code>math.floor</code></a>, and <a href="#pdf-math.modf"><code>math.modf</code></a>) +return an integer when the result fits in the range of an integer, +or a float otherwise. + + +<p> +<hr><h3><a name="pdf-math.abs"><code>math.abs (x)</code></a></h3> + + +<p> +Returns the absolute value of <code>x</code>. (integer/float) + + + + +<p> +<hr><h3><a name="pdf-math.acos"><code>math.acos (x)</code></a></h3> + + +<p> +Returns the arc cosine of <code>x</code> (in radians). + + + + +<p> +<hr><h3><a name="pdf-math.asin"><code>math.asin (x)</code></a></h3> + + +<p> +Returns the arc sine of <code>x</code> (in radians). + + + + +<p> +<hr><h3><a name="pdf-math.atan"><code>math.atan (y [, x])</code></a></h3> + + +<p> + +Returns the arc tangent of <code>y/x</code> (in radians), +but uses the signs of both arguments to find the +quadrant of the result. +(It also handles correctly the case of <code>x</code> being zero.) + + +<p> +The default value for <code>x</code> is 1, +so that the call <code>math.atan(y)</code> +returns the arc tangent of <code>y</code>. + + + + +<p> +<hr><h3><a name="pdf-math.ceil"><code>math.ceil (x)</code></a></h3> + + +<p> +Returns the smallest integral value larger than or equal to <code>x</code>. + + + + +<p> +<hr><h3><a name="pdf-math.cos"><code>math.cos (x)</code></a></h3> + + +<p> +Returns the cosine of <code>x</code> (assumed to be in radians). + + + + +<p> +<hr><h3><a name="pdf-math.deg"><code>math.deg (x)</code></a></h3> + + +<p> +Converts the angle <code>x</code> from radians to degrees. + + + + +<p> +<hr><h3><a name="pdf-math.exp"><code>math.exp (x)</code></a></h3> + + +<p> +Returns the value <em>e<sup>x</sup></em> +(where <code>e</code> is the base of natural logarithms). + + + + +<p> +<hr><h3><a name="pdf-math.floor"><code>math.floor (x)</code></a></h3> + + +<p> +Returns the largest integral value smaller than or equal to <code>x</code>. + + + + +<p> +<hr><h3><a name="pdf-math.fmod"><code>math.fmod (x, y)</code></a></h3> + + +<p> +Returns the remainder of the division of <code>x</code> by <code>y</code> +that rounds the quotient towards zero. (integer/float) + + + + +<p> +<hr><h3><a name="pdf-math.huge"><code>math.huge</code></a></h3> + + +<p> +The float value <code>HUGE_VAL</code>, +a value larger than any other numeric value. + + + + +<p> +<hr><h3><a name="pdf-math.log"><code>math.log (x [, base])</code></a></h3> + + +<p> +Returns the logarithm of <code>x</code> in the given base. +The default for <code>base</code> is <em>e</em> +(so that the function returns the natural logarithm of <code>x</code>). + + + + +<p> +<hr><h3><a name="pdf-math.max"><code>math.max (x, ···)</code></a></h3> + + +<p> +Returns the argument with the maximum value, +according to the Lua operator <code><</code>. (integer/float) + + + + +<p> +<hr><h3><a name="pdf-math.maxinteger"><code>math.maxinteger</code></a></h3> +An integer with the maximum value for an integer. + + + + +<p> +<hr><h3><a name="pdf-math.min"><code>math.min (x, ···)</code></a></h3> + + +<p> +Returns the argument with the minimum value, +according to the Lua operator <code><</code>. (integer/float) + + + + +<p> +<hr><h3><a name="pdf-math.mininteger"><code>math.mininteger</code></a></h3> +An integer with the minimum value for an integer. + + + + +<p> +<hr><h3><a name="pdf-math.modf"><code>math.modf (x)</code></a></h3> + + +<p> +Returns the integral part of <code>x</code> and the fractional part of <code>x</code>. +Its second result is always a float. + + + + +<p> +<hr><h3><a name="pdf-math.pi"><code>math.pi</code></a></h3> + + +<p> +The value of <em>π</em>. + + + + +<p> +<hr><h3><a name="pdf-math.rad"><code>math.rad (x)</code></a></h3> + + +<p> +Converts the angle <code>x</code> from degrees to radians. + + + + +<p> +<hr><h3><a name="pdf-math.random"><code>math.random ([m [, n]])</code></a></h3> + + +<p> +When called without arguments, +returns a pseudo-random float with uniform distribution +in the range <em>[0,1)</em>. +When called with two integers <code>m</code> and <code>n</code>, +<code>math.random</code> returns a pseudo-random integer +with uniform distribution in the range <em>[m, n]</em>. +(The value <em>n-m</em> cannot be negative and must fit in a Lua integer.) +The call <code>math.random(n)</code> is equivalent to <code>math.random(1,n)</code>. + + +<p> +This function is an interface to the underling +pseudo-random generator function provided by C. + + + + +<p> +<hr><h3><a name="pdf-math.randomseed"><code>math.randomseed (x)</code></a></h3> + + +<p> +Sets <code>x</code> as the "seed" +for the pseudo-random generator: +equal seeds produce equal sequences of numbers. + + + + +<p> +<hr><h3><a name="pdf-math.sin"><code>math.sin (x)</code></a></h3> + + +<p> +Returns the sine of <code>x</code> (assumed to be in radians). + + + + +<p> +<hr><h3><a name="pdf-math.sqrt"><code>math.sqrt (x)</code></a></h3> + + +<p> +Returns the square root of <code>x</code>. +(You can also use the expression <code>x^0.5</code> to compute this value.) + + + + +<p> +<hr><h3><a name="pdf-math.tan"><code>math.tan (x)</code></a></h3> + + +<p> +Returns the tangent of <code>x</code> (assumed to be in radians). + + + + +<p> +<hr><h3><a name="pdf-math.tointeger"><code>math.tointeger (x)</code></a></h3> + + +<p> +If the value <code>x</code> is convertible to an integer, +returns that integer. +Otherwise, returns <b>nil</b>. + + + + +<p> +<hr><h3><a name="pdf-math.type"><code>math.type (x)</code></a></h3> + + +<p> +Returns "<code>integer</code>" if <code>x</code> is an integer, +"<code>float</code>" if it is a float, +or <b>nil</b> if <code>x</code> is not a number. + + + + +<p> +<hr><h3><a name="pdf-math.ult"><code>math.ult (m, n)</code></a></h3> + + +<p> +Returns a boolean, +true if and only if integer <code>m</code> is below integer <code>n</code> when +they are compared as unsigned integers. + + + + + + + +<h2>6.8 – <a name="6.8">Input and Output Facilities</a></h2> + +<p> +The I/O library provides two different styles for file manipulation. +The first one uses implicit file handles; +that is, there are operations to set a default input file and a +default output file, +and all input/output operations are over these default files. +The second style uses explicit file handles. + + +<p> +When using implicit file handles, +all operations are supplied by table <a name="pdf-io"><code>io</code></a>. +When using explicit file handles, +the operation <a href="#pdf-io.open"><code>io.open</code></a> returns a file handle +and then all operations are supplied as methods of the file handle. + + +<p> +The table <code>io</code> also provides +three predefined file handles with their usual meanings from C: +<a name="pdf-io.stdin"><code>io.stdin</code></a>, <a name="pdf-io.stdout"><code>io.stdout</code></a>, and <a name="pdf-io.stderr"><code>io.stderr</code></a>. +The I/O library never closes these files. + + +<p> +Unless otherwise stated, +all I/O functions return <b>nil</b> on failure +(plus an error message as a second result and +a system-dependent error code as a third result) +and some value different from <b>nil</b> on success. +In non-POSIX systems, +the computation of the error message and error code +in case of errors +may be not thread safe, +because they rely on the global C variable <code>errno</code>. + + +<p> +<hr><h3><a name="pdf-io.close"><code>io.close ([file])</code></a></h3> + + +<p> +Equivalent to <code>file:close()</code>. +Without a <code>file</code>, closes the default output file. + + + + +<p> +<hr><h3><a name="pdf-io.flush"><code>io.flush ()</code></a></h3> + + +<p> +Equivalent to <code>io.output():flush()</code>. + + + + +<p> +<hr><h3><a name="pdf-io.input"><code>io.input ([file])</code></a></h3> + + +<p> +When called with a file name, it opens the named file (in text mode), +and sets its handle as the default input file. +When called with a file handle, +it simply sets this file handle as the default input file. +When called without arguments, +it returns the current default input file. + + +<p> +In case of errors this function raises the error, +instead of returning an error code. + + + + +<p> +<hr><h3><a name="pdf-io.lines"><code>io.lines ([filename, ···])</code></a></h3> + + +<p> +Opens the given file name in read mode +and returns an iterator function that +works like <code>file:lines(···)</code> over the opened file. +When the iterator function detects the end of file, +it returns no values (to finish the loop) and automatically closes the file. + + +<p> +The call <code>io.lines()</code> (with no file name) is equivalent +to <code>io.input():lines("*l")</code>; +that is, it iterates over the lines of the default input file. +In this case, the iterator does not close the file when the loop ends. + + +<p> +In case of errors this function raises the error, +instead of returning an error code. + + + + +<p> +<hr><h3><a name="pdf-io.open"><code>io.open (filename [, mode])</code></a></h3> + + +<p> +This function opens a file, +in the mode specified in the string <code>mode</code>. +In case of success, +it returns a new file handle. + + +<p> +The <code>mode</code> string can be any of the following: + +<ul> +<li><b>"<code>r</code>": </b> read mode (the default);</li> +<li><b>"<code>w</code>": </b> write mode;</li> +<li><b>"<code>a</code>": </b> append mode;</li> +<li><b>"<code>r+</code>": </b> update mode, all previous data is preserved;</li> +<li><b>"<code>w+</code>": </b> update mode, all previous data is erased;</li> +<li><b>"<code>a+</code>": </b> append update mode, previous data is preserved, + writing is only allowed at the end of file.</li> +</ul><p> +The <code>mode</code> string can also have a '<code>b</code>' at the end, +which is needed in some systems to open the file in binary mode. + + + + +<p> +<hr><h3><a name="pdf-io.output"><code>io.output ([file])</code></a></h3> + + +<p> +Similar to <a href="#pdf-io.input"><code>io.input</code></a>, but operates over the default output file. + + + + +<p> +<hr><h3><a name="pdf-io.popen"><code>io.popen (prog [, mode])</code></a></h3> + + +<p> +This function is system dependent and is not available +on all platforms. + + +<p> +Starts program <code>prog</code> in a separated process and returns +a file handle that you can use to read data from this program +(if <code>mode</code> is <code>"r"</code>, the default) +or to write data to this program +(if <code>mode</code> is <code>"w"</code>). + + + + +<p> +<hr><h3><a name="pdf-io.read"><code>io.read (···)</code></a></h3> + + +<p> +Equivalent to <code>io.input():read(···)</code>. + + + + +<p> +<hr><h3><a name="pdf-io.tmpfile"><code>io.tmpfile ()</code></a></h3> + + +<p> +In case of success, +returns a handle for a temporary file. +This file is opened in update mode +and it is automatically removed when the program ends. + + + + +<p> +<hr><h3><a name="pdf-io.type"><code>io.type (obj)</code></a></h3> + + +<p> +Checks whether <code>obj</code> is a valid file handle. +Returns the string <code>"file"</code> if <code>obj</code> is an open file handle, +<code>"closed file"</code> if <code>obj</code> is a closed file handle, +or <b>nil</b> if <code>obj</code> is not a file handle. + + + + +<p> +<hr><h3><a name="pdf-io.write"><code>io.write (···)</code></a></h3> + + +<p> +Equivalent to <code>io.output():write(···)</code>. + + + + +<p> +<hr><h3><a name="pdf-file:close"><code>file:close ()</code></a></h3> + + +<p> +Closes <code>file</code>. +Note that files are automatically closed when +their handles are garbage collected, +but that takes an unpredictable amount of time to happen. + + +<p> +When closing a file handle created with <a href="#pdf-io.popen"><code>io.popen</code></a>, +<a href="#pdf-file:close"><code>file:close</code></a> returns the same values +returned by <a href="#pdf-os.execute"><code>os.execute</code></a>. + + + + +<p> +<hr><h3><a name="pdf-file:flush"><code>file:flush ()</code></a></h3> + + +<p> +Saves any written data to <code>file</code>. + + + + +<p> +<hr><h3><a name="pdf-file:lines"><code>file:lines (···)</code></a></h3> + + +<p> +Returns an iterator function that, +each time it is called, +reads the file according to the given formats. +When no format is given, +uses "<code>l</code>" as a default. +As an example, the construction + +<pre> + for c in file:lines(1) do <em>body</em> end +</pre><p> +will iterate over all characters of the file, +starting at the current position. +Unlike <a href="#pdf-io.lines"><code>io.lines</code></a>, this function does not close the file +when the loop ends. + + +<p> +In case of errors this function raises the error, +instead of returning an error code. + + + + +<p> +<hr><h3><a name="pdf-file:read"><code>file:read (···)</code></a></h3> + + +<p> +Reads the file <code>file</code>, +according to the given formats, which specify what to read. +For each format, +the function returns a string or a number with the characters read, +or <b>nil</b> if it cannot read data with the specified format. +(In this latter case, +the function does not read subsequent formats.) +When called without formats, +it uses a default format that reads the next line +(see below). + + +<p> +The available formats are + +<ul> + +<li><b>"<code>n</code>": </b> +reads a numeral and returns it as a float or an integer, +following the lexical conventions of Lua. +(The numeral may have leading spaces and a sign.) +This format always reads the longest input sequence that +is a valid prefix for a numeral; +if that prefix does not form a valid numeral +(e.g., an empty string, "<code>0x</code>", or "<code>3.4e-</code>"), +it is discarded and the function returns <b>nil</b>. +</li> + +<li><b>"<code>a</code>": </b> +reads the whole file, starting at the current position. +On end of file, it returns the empty string. +</li> + +<li><b>"<code>l</code>": </b> +reads the next line skipping the end of line, +returning <b>nil</b> on end of file. +This is the default format. +</li> + +<li><b>"<code>L</code>": </b> +reads the next line keeping the end-of-line character (if present), +returning <b>nil</b> on end of file. +</li> + +<li><b><em>number</em>: </b> +reads a string with up to this number of bytes, +returning <b>nil</b> on end of file. +If <code>number</code> is zero, +it reads nothing and returns an empty string, +or <b>nil</b> on end of file. +</li> + +</ul><p> +The formats "<code>l</code>" and "<code>L</code>" should be used only for text files. + + + + +<p> +<hr><h3><a name="pdf-file:seek"><code>file:seek ([whence [, offset]])</code></a></h3> + + +<p> +Sets and gets the file position, +measured from the beginning of the file, +to the position given by <code>offset</code> plus a base +specified by the string <code>whence</code>, as follows: + +<ul> +<li><b>"<code>set</code>": </b> base is position 0 (beginning of the file);</li> +<li><b>"<code>cur</code>": </b> base is current position;</li> +<li><b>"<code>end</code>": </b> base is end of file;</li> +</ul><p> +In case of success, <code>seek</code> returns the final file position, +measured in bytes from the beginning of the file. +If <code>seek</code> fails, it returns <b>nil</b>, +plus a string describing the error. + + +<p> +The default value for <code>whence</code> is <code>"cur"</code>, +and for <code>offset</code> is 0. +Therefore, the call <code>file:seek()</code> returns the current +file position, without changing it; +the call <code>file:seek("set")</code> sets the position to the +beginning of the file (and returns 0); +and the call <code>file:seek("end")</code> sets the position to the +end of the file, and returns its size. + + + + +<p> +<hr><h3><a name="pdf-file:setvbuf"><code>file:setvbuf (mode [, size])</code></a></h3> + + +<p> +Sets the buffering mode for an output file. +There are three available modes: + +<ul> + +<li><b>"<code>no</code>": </b> +no buffering; the result of any output operation appears immediately. +</li> + +<li><b>"<code>full</code>": </b> +full buffering; output operation is performed only +when the buffer is full or when +you explicitly <code>flush</code> the file (see <a href="#pdf-io.flush"><code>io.flush</code></a>). +</li> + +<li><b>"<code>line</code>": </b> +line buffering; output is buffered until a newline is output +or there is any input from some special files +(such as a terminal device). +</li> + +</ul><p> +For the last two cases, <code>size</code> +specifies the size of the buffer, in bytes. +The default is an appropriate size. + + + + +<p> +<hr><h3><a name="pdf-file:write"><code>file:write (···)</code></a></h3> + + +<p> +Writes the value of each of its arguments to <code>file</code>. +The arguments must be strings or numbers. + + +<p> +In case of success, this function returns <code>file</code>. +Otherwise it returns <b>nil</b> plus a string describing the error. + + + + + + + +<h2>6.9 – <a name="6.9">Operating System Facilities</a></h2> + +<p> +This library is implemented through table <a name="pdf-os"><code>os</code></a>. + + +<p> +<hr><h3><a name="pdf-os.clock"><code>os.clock ()</code></a></h3> + + +<p> +Returns an approximation of the amount in seconds of CPU time +used by the program. + + + + +<p> +<hr><h3><a name="pdf-os.date"><code>os.date ([format [, time]])</code></a></h3> + + +<p> +Returns a string or a table containing date and time, +formatted according to the given string <code>format</code>. + + +<p> +If the <code>time</code> argument is present, +this is the time to be formatted +(see the <a href="#pdf-os.time"><code>os.time</code></a> function for a description of this value). +Otherwise, <code>date</code> formats the current time. + + +<p> +If <code>format</code> starts with '<code>!</code>', +then the date is formatted in Coordinated Universal Time. +After this optional character, +if <code>format</code> is the string "<code>*t</code>", +then <code>date</code> returns a table with the following fields: +<code>year</code>, <code>month</code> (1–12), <code>day</code> (1–31), +<code>hour</code> (0–23), <code>min</code> (0–59), <code>sec</code> (0–61), +<code>wday</code> (weekday, 1–7, Sunday is 1), +<code>yday</code> (day of the year, 1–366), +and <code>isdst</code> (daylight saving flag, a boolean). +This last field may be absent +if the information is not available. + + +<p> +If <code>format</code> is not "<code>*t</code>", +then <code>date</code> returns the date as a string, +formatted according to the same rules as the ISO C function <code>strftime</code>. + + +<p> +When called without arguments, +<code>date</code> returns a reasonable date and time representation that depends on +the host system and on the current locale. +(More specifically, <code>os.date()</code> is equivalent to <code>os.date("%c")</code>.) + + +<p> +In non-POSIX systems, +this function may be not thread safe +because of its reliance on C function <code>gmtime</code> and C function <code>localtime</code>. + + + + +<p> +<hr><h3><a name="pdf-os.difftime"><code>os.difftime (t2, t1)</code></a></h3> + + +<p> +Returns the difference, in seconds, +from time <code>t1</code> to time <code>t2</code> +(where the times are values returned by <a href="#pdf-os.time"><code>os.time</code></a>). +In POSIX, Windows, and some other systems, +this value is exactly <code>t2</code><em>-</em><code>t1</code>. + + + + +<p> +<hr><h3><a name="pdf-os.execute"><code>os.execute ([command])</code></a></h3> + + +<p> +This function is equivalent to the ISO C function <code>system</code>. +It passes <code>command</code> to be executed by an operating system shell. +Its first result is <b>true</b> +if the command terminated successfully, +or <b>nil</b> otherwise. +After this first result +the function returns a string plus a number, +as follows: + +<ul> + +<li><b>"<code>exit</code>": </b> +the command terminated normally; +the following number is the exit status of the command. +</li> + +<li><b>"<code>signal</code>": </b> +the command was terminated by a signal; +the following number is the signal that terminated the command. +</li> + +</ul> + +<p> +When called without a <code>command</code>, +<code>os.execute</code> returns a boolean that is true if a shell is available. + + + + +<p> +<hr><h3><a name="pdf-os.exit"><code>os.exit ([code [, close]])</code></a></h3> + + +<p> +Calls the ISO C function <code>exit</code> to terminate the host program. +If <code>code</code> is <b>true</b>, +the returned status is <code>EXIT_SUCCESS</code>; +if <code>code</code> is <b>false</b>, +the returned status is <code>EXIT_FAILURE</code>; +if <code>code</code> is a number, +the returned status is this number. +The default value for <code>code</code> is <b>true</b>. + + +<p> +If the optional second argument <code>close</code> is true, +closes the Lua state before exiting. + + + + +<p> +<hr><h3><a name="pdf-os.getenv"><code>os.getenv (varname)</code></a></h3> + + +<p> +Returns the value of the process environment variable <code>varname</code>, +or <b>nil</b> if the variable is not defined. + + + + +<p> +<hr><h3><a name="pdf-os.remove"><code>os.remove (filename)</code></a></h3> + + +<p> +Deletes the file (or empty directory, on POSIX systems) +with the given name. +If this function fails, it returns <b>nil</b>, +plus a string describing the error and the error code. +Otherwise, it returns true. + + + + +<p> +<hr><h3><a name="pdf-os.rename"><code>os.rename (oldname, newname)</code></a></h3> + + +<p> +Renames the file or directory named <code>oldname</code> to <code>newname</code>. +If this function fails, it returns <b>nil</b>, +plus a string describing the error and the error code. +Otherwise, it returns true. + + + + +<p> +<hr><h3><a name="pdf-os.setlocale"><code>os.setlocale (locale [, category])</code></a></h3> + + +<p> +Sets the current locale of the program. +<code>locale</code> is a system-dependent string specifying a locale; +<code>category</code> is an optional string describing which category to change: +<code>"all"</code>, <code>"collate"</code>, <code>"ctype"</code>, +<code>"monetary"</code>, <code>"numeric"</code>, or <code>"time"</code>; +the default category is <code>"all"</code>. +The function returns the name of the new locale, +or <b>nil</b> if the request cannot be honored. + + +<p> +If <code>locale</code> is the empty string, +the current locale is set to an implementation-defined native locale. +If <code>locale</code> is the string "<code>C</code>", +the current locale is set to the standard C locale. + + +<p> +When called with <b>nil</b> as the first argument, +this function only returns the name of the current locale +for the given category. + + +<p> +This function may be not thread safe +because of its reliance on C function <code>setlocale</code>. + + + + +<p> +<hr><h3><a name="pdf-os.time"><code>os.time ([table])</code></a></h3> + + +<p> +Returns the current time when called without arguments, +or a time representing the local date and time specified by the given table. +This table must have fields <code>year</code>, <code>month</code>, and <code>day</code>, +and may have fields +<code>hour</code> (default is 12), +<code>min</code> (default is 0), +<code>sec</code> (default is 0), +and <code>isdst</code> (default is <b>nil</b>). +Other fields are ignored. +For a description of these fields, see the <a href="#pdf-os.date"><code>os.date</code></a> function. + + +<p> +The values in these fields do not need to be inside their valid ranges. +For instance, if <code>sec</code> is -10, +it means -10 seconds from the time specified by the other fields; +if <code>hour</code> is 1000, +it means +1000 hours from the time specified by the other fields. + + +<p> +The returned value is a number, whose meaning depends on your system. +In POSIX, Windows, and some other systems, +this number counts the number +of seconds since some given start time (the "epoch"). +In other systems, the meaning is not specified, +and the number returned by <code>time</code> can be used only as an argument to +<a href="#pdf-os.date"><code>os.date</code></a> and <a href="#pdf-os.difftime"><code>os.difftime</code></a>. + + + + +<p> +<hr><h3><a name="pdf-os.tmpname"><code>os.tmpname ()</code></a></h3> + + +<p> +Returns a string with a file name that can +be used for a temporary file. +The file must be explicitly opened before its use +and explicitly removed when no longer needed. + + +<p> +In POSIX systems, +this function also creates a file with that name, +to avoid security risks. +(Someone else might create the file with wrong permissions +in the time between getting the name and creating the file.) +You still have to open the file to use it +and to remove it (even if you do not use it). + + +<p> +When possible, +you may prefer to use <a href="#pdf-io.tmpfile"><code>io.tmpfile</code></a>, +which automatically removes the file when the program ends. + + + + + + + +<h2>6.10 – <a name="6.10">The Debug Library</a></h2> + +<p> +This library provides +the functionality of the debug interface (<a href="#4.9">§4.9</a>) to Lua programs. +You should exert care when using this library. +Several of its functions +violate basic assumptions about Lua code +(e.g., that variables local to a function +cannot be accessed from outside; +that userdata metatables cannot be changed by Lua code; +that Lua programs do not crash) +and therefore can compromise otherwise secure code. +Moreover, some functions in this library may be slow. + + +<p> +All functions in this library are provided +inside the <a name="pdf-debug"><code>debug</code></a> table. +All functions that operate over a thread +have an optional first argument which is the +thread to operate over. +The default is always the current thread. + + +<p> +<hr><h3><a name="pdf-debug.debug"><code>debug.debug ()</code></a></h3> + + +<p> +Enters an interactive mode with the user, +running each string that the user enters. +Using simple commands and other debug facilities, +the user can inspect global and local variables, +change their values, evaluate expressions, and so on. +A line containing only the word <code>cont</code> finishes this function, +so that the caller continues its execution. + + +<p> +Note that commands for <code>debug.debug</code> are not lexically nested +within any function and so have no direct access to local variables. + + + + +<p> +<hr><h3><a name="pdf-debug.gethook"><code>debug.gethook ([thread])</code></a></h3> + + +<p> +Returns the current hook settings of the thread, as three values: +the current hook function, the current hook mask, +and the current hook count +(as set by the <a href="#pdf-debug.sethook"><code>debug.sethook</code></a> function). + + + + +<p> +<hr><h3><a name="pdf-debug.getinfo"><code>debug.getinfo ([thread,] f [, what])</code></a></h3> + + +<p> +Returns a table with information about a function. +You can give the function directly +or you can give a number as the value of <code>f</code>, +which means the function running at level <code>f</code> of the call stack +of the given thread: +level 0 is the current function (<code>getinfo</code> itself); +level 1 is the function that called <code>getinfo</code> +(except for tail calls, which do not count on the stack); +and so on. +If <code>f</code> is a number larger than the number of active functions, +then <code>getinfo</code> returns <b>nil</b>. + + +<p> +The returned table can contain all the fields returned by <a href="#lua_getinfo"><code>lua_getinfo</code></a>, +with the string <code>what</code> describing which fields to fill in. +The default for <code>what</code> is to get all information available, +except the table of valid lines. +If present, +the option '<code>f</code>' +adds a field named <code>func</code> with the function itself. +If present, +the option '<code>L</code>' +adds a field named <code>activelines</code> with the table of +valid lines. + + +<p> +For instance, the expression <code>debug.getinfo(1,"n").name</code> returns +a name for the current function, +if a reasonable name can be found, +and the expression <code>debug.getinfo(print)</code> +returns a table with all available information +about the <a href="#pdf-print"><code>print</code></a> function. + + + + +<p> +<hr><h3><a name="pdf-debug.getlocal"><code>debug.getlocal ([thread,] f, local)</code></a></h3> + + +<p> +This function returns the name and the value of the local variable +with index <code>local</code> of the function at level <code>f</code> of the stack. +This function accesses not only explicit local variables, +but also parameters, temporaries, etc. + + +<p> +The first parameter or local variable has index 1, and so on, +following the order that they are declared in the code, +counting only the variables that are active +in the current scope of the function. +Negative indices refer to vararg arguments; +-1 is the first vararg argument. +The function returns <b>nil</b> if there is no variable with the given index, +and raises an error when called with a level out of range. +(You can call <a href="#pdf-debug.getinfo"><code>debug.getinfo</code></a> to check whether the level is valid.) + + +<p> +Variable names starting with '<code>(</code>' (open parenthesis) +represent variables with no known names +(internal variables such as loop control variables, +and variables from chunks saved without debug information). + + +<p> +The parameter <code>f</code> may also be a function. +In that case, <code>getlocal</code> returns only the name of function parameters. + + + + +<p> +<hr><h3><a name="pdf-debug.getmetatable"><code>debug.getmetatable (value)</code></a></h3> + + +<p> +Returns the metatable of the given <code>value</code> +or <b>nil</b> if it does not have a metatable. + + + + +<p> +<hr><h3><a name="pdf-debug.getregistry"><code>debug.getregistry ()</code></a></h3> + + +<p> +Returns the registry table (see <a href="#4.5">§4.5</a>). + + + + +<p> +<hr><h3><a name="pdf-debug.getupvalue"><code>debug.getupvalue (f, up)</code></a></h3> + + +<p> +This function returns the name and the value of the upvalue +with index <code>up</code> of the function <code>f</code>. +The function returns <b>nil</b> if there is no upvalue with the given index. + + +<p> +Variable names starting with '<code>(</code>' (open parenthesis) +represent variables with no known names +(variables from chunks saved without debug information). + + + + +<p> +<hr><h3><a name="pdf-debug.getuservalue"><code>debug.getuservalue (u)</code></a></h3> + + +<p> +Returns the Lua value associated to <code>u</code>. +If <code>u</code> is not a full userdata, +returns <b>nil</b>. + + + + +<p> +<hr><h3><a name="pdf-debug.sethook"><code>debug.sethook ([thread,] hook, mask [, count])</code></a></h3> + + +<p> +Sets the given function as a hook. +The string <code>mask</code> and the number <code>count</code> describe +when the hook will be called. +The string mask may have any combination of the following characters, +with the given meaning: + +<ul> +<li><b>'<code>c</code>': </b> the hook is called every time Lua calls a function;</li> +<li><b>'<code>r</code>': </b> the hook is called every time Lua returns from a function;</li> +<li><b>'<code>l</code>': </b> the hook is called every time Lua enters a new line of code.</li> +</ul><p> +Moreover, +with a <code>count</code> different from zero, +the hook is called also after every <code>count</code> instructions. + + +<p> +When called without arguments, +<a href="#pdf-debug.sethook"><code>debug.sethook</code></a> turns off the hook. + + +<p> +When the hook is called, its first argument is a string +describing the event that has triggered its call: +<code>"call"</code> (or <code>"tail call"</code>), +<code>"return"</code>, +<code>"line"</code>, and <code>"count"</code>. +For line events, +the hook also gets the new line number as its second parameter. +Inside a hook, +you can call <code>getinfo</code> with level 2 to get more information about +the running function +(level 0 is the <code>getinfo</code> function, +and level 1 is the hook function). + + + + +<p> +<hr><h3><a name="pdf-debug.setlocal"><code>debug.setlocal ([thread,] level, local, value)</code></a></h3> + + +<p> +This function assigns the value <code>value</code> to the local variable +with index <code>local</code> of the function at level <code>level</code> of the stack. +The function returns <b>nil</b> if there is no local +variable with the given index, +and raises an error when called with a <code>level</code> out of range. +(You can call <code>getinfo</code> to check whether the level is valid.) +Otherwise, it returns the name of the local variable. + + +<p> +See <a href="#pdf-debug.getlocal"><code>debug.getlocal</code></a> for more information about +variable indices and names. + + + + +<p> +<hr><h3><a name="pdf-debug.setmetatable"><code>debug.setmetatable (value, table)</code></a></h3> + + +<p> +Sets the metatable for the given <code>value</code> to the given <code>table</code> +(which can be <b>nil</b>). +Returns <code>value</code>. + + + + +<p> +<hr><h3><a name="pdf-debug.setupvalue"><code>debug.setupvalue (f, up, value)</code></a></h3> + + +<p> +This function assigns the value <code>value</code> to the upvalue +with index <code>up</code> of the function <code>f</code>. +The function returns <b>nil</b> if there is no upvalue +with the given index. +Otherwise, it returns the name of the upvalue. + + + + +<p> +<hr><h3><a name="pdf-debug.setuservalue"><code>debug.setuservalue (udata, value)</code></a></h3> + + +<p> +Sets the given <code>value</code> as +the Lua value associated to the given <code>udata</code>. +<code>udata</code> must be a full userdata. + + +<p> +Returns <code>udata</code>. + + + + +<p> +<hr><h3><a name="pdf-debug.traceback"><code>debug.traceback ([thread,] [message [, level]])</code></a></h3> + + +<p> +If <code>message</code> is present but is neither a string nor <b>nil</b>, +this function returns <code>message</code> without further processing. +Otherwise, +it returns a string with a traceback of the call stack. +The optional <code>message</code> string is appended +at the beginning of the traceback. +An optional <code>level</code> number tells at which level +to start the traceback +(default is 1, the function calling <code>traceback</code>). + + + + +<p> +<hr><h3><a name="pdf-debug.upvalueid"><code>debug.upvalueid (f, n)</code></a></h3> + + +<p> +Returns a unique identifier (as a light userdata) +for the upvalue numbered <code>n</code> +from the given function. + + +<p> +These unique identifiers allow a program to check whether different +closures share upvalues. +Lua closures that share an upvalue +(that is, that access a same external local variable) +will return identical ids for those upvalue indices. + + + + +<p> +<hr><h3><a name="pdf-debug.upvaluejoin"><code>debug.upvaluejoin (f1, n1, f2, n2)</code></a></h3> + + +<p> +Make the <code>n1</code>-th upvalue of the Lua closure <code>f1</code> +refer to the <code>n2</code>-th upvalue of the Lua closure <code>f2</code>. + + + + + + + +<h1>7 – <a name="7">Lua Standalone</a></h1> + +<p> +Although Lua has been designed as an extension language, +to be embedded in a host C program, +it is also frequently used as a standalone language. +An interpreter for Lua as a standalone language, +called simply <code>lua</code>, +is provided with the standard distribution. +The standalone interpreter includes +all standard libraries, including the debug library. +Its usage is: + +<pre> + lua [options] [script [args]] +</pre><p> +The options are: + +<ul> +<li><b><code>-e <em>stat</em></code>: </b> executes string <em>stat</em>;</li> +<li><b><code>-l <em>mod</em></code>: </b> "requires" <em>mod</em> and assigns the + result to global @<em>mod</em>;</li> +<li><b><code>-i</code>: </b> enters interactive mode after running <em>script</em>;</li> +<li><b><code>-v</code>: </b> prints version information;</li> +<li><b><code>-E</code>: </b> ignores environment variables;</li> +<li><b><code>--</code>: </b> stops handling options;</li> +<li><b><code>-</code>: </b> executes <code>stdin</code> as a file and stops handling options.</li> +</ul><p> +After handling its options, <code>lua</code> runs the given <em>script</em>. +When called without arguments, +<code>lua</code> behaves as <code>lua -v -i</code> +when the standard input (<code>stdin</code>) is a terminal, +and as <code>lua -</code> otherwise. + + +<p> +When called without option <code>-E</code>, +the interpreter checks for an environment variable <a name="pdf-LUA_INIT_5_3"><code>LUA_INIT_5_3</code></a> +(or <a name="pdf-LUA_INIT"><code>LUA_INIT</code></a> if the versioned name is not defined) +before running any argument. +If the variable content has the format <code>@<em>filename</em></code>, +then <code>lua</code> executes the file. +Otherwise, <code>lua</code> executes the string itself. + + +<p> +When called with option <code>-E</code>, +besides ignoring <code>LUA_INIT</code>, +Lua also ignores +the values of <code>LUA_PATH</code> and <code>LUA_CPATH</code>, +setting the values of +<a href="#pdf-package.path"><code>package.path</code></a> and <a href="#pdf-package.cpath"><code>package.cpath</code></a> +with the default paths defined in <code>luaconf.h</code>. + + +<p> +All options are handled in order, except <code>-i</code> and <code>-E</code>. +For instance, an invocation like + +<pre> + $ lua -e'a=1' -e 'print(a)' script.lua +</pre><p> +will first set <code>a</code> to 1, then print the value of <code>a</code>, +and finally run the file <code>script.lua</code> with no arguments. +(Here <code>$</code> is the shell prompt. Your prompt may be different.) + + +<p> +Before running any code, +<code>lua</code> collects all command-line arguments +in a global table called <code>arg</code>. +The script name goes to index 0, +the first argument after the script name goes to index 1, +and so on. +Any arguments before the script name +(that is, the interpreter name plus its options) +go to negative indices. +For instance, in the call + +<pre> + $ lua -la b.lua t1 t2 +</pre><p> +the table is like this: + +<pre> + arg = { [-2] = "lua", [-1] = "-la", + [0] = "b.lua", + [1] = "t1", [2] = "t2" } +</pre><p> +If there is no script in the call, +the interpreter name goes to index 0, +followed by the other arguments. +For instance, the call + +<pre> + $ lua -e "print(arg[1])" +</pre><p> +will print "<code>-e</code>". +If there is a script, +the script is called with arguments +<code>arg[1]</code>, ···, <code>arg[#arg]</code>. +(Like all chunks in Lua, +the script is compiled as a vararg function.) + + +<p> +In interactive mode, +Lua repeatedly prompts and waits for a line. +After reading a line, +Lua first try to interpret the line as an expression. +If it succeeds, it prints its value. +Otherwise, it interprets the line as a statement. +If you write an incomplete statement, +the interpreter waits for its completion +by issuing a different prompt. + + +<p> +If the global variable <a name="pdf-_PROMPT"><code>_PROMPT</code></a> contains a string, +then its value is used as the prompt. +Similarly, if the global variable <a name="pdf-_PROMPT2"><code>_PROMPT2</code></a> contains a string, +its value is used as the secondary prompt +(issued during incomplete statements). + + +<p> +In case of unprotected errors in the script, +the interpreter reports the error to the standard error stream. +If the error object is not a string but +has a metamethod <code>__tostring</code>, +the interpreter calls this metamethod to produce the final message. +Otherwise, the interpreter converts the error object to a string +and adds a stack traceback to it. + + +<p> +When finishing normally, +the interpreter closes its main Lua state +(see <a href="#lua_close"><code>lua_close</code></a>). +The script can avoid this step by +calling <a href="#pdf-os.exit"><code>os.exit</code></a> to terminate. + + +<p> +To allow the use of Lua as a +script interpreter in Unix systems, +the standalone interpreter skips +the first line of a chunk if it starts with <code>#</code>. +Therefore, Lua scripts can be made into executable programs +by using <code>chmod +x</code> and the <code>#!</code> form, +as in + +<pre> + #!/usr/local/bin/lua +</pre><p> +(Of course, +the location of the Lua interpreter may be different in your machine. +If <code>lua</code> is in your <code>PATH</code>, +then + +<pre> + #!/usr/bin/env lua +</pre><p> +is a more portable solution.) + + + +<h1>8 – <a name="8">Incompatibilities with the Previous Version</a></h1> + +<p> +Here we list the incompatibilities that you may find when moving a program +from Lua 5.2 to Lua 5.3. +You can avoid some incompatibilities by compiling Lua with +appropriate options (see file <code>luaconf.h</code>). +However, +all these compatibility options will be removed in the future. + + +<p> +Lua versions can always change the C API in ways that +do not imply source-code changes in a program, +such as the numeric values for constants +or the implementation of functions as macros. +Therefore, +you should not assume that binaries are compatible between +different Lua versions. +Always recompile clients of the Lua API when +using a new version. + + +<p> +Similarly, Lua versions can always change the internal representation +of precompiled chunks; +precompiled chunks are not compatible between different Lua versions. + + +<p> +The standard paths in the official distribution may +change between versions. + + + +<h2>8.1 – <a name="8.1">Changes in the Language</a></h2> +<ul> + +<li> +The main difference between Lua 5.2 and Lua 5.3 is the +introduction of an integer subtype for numbers. +Although this change should not affect "normal" computations, +some computations +(mainly those that involve some kind of overflow) +can give different results. + + +<p> +You can fix these differences by forcing a number to be a float +(in Lua 5.2 all numbers were float), +in particular writing constants with an ending <code>.0</code> +or using <code>x = x + 0.0</code> to convert a variable. +(This recommendation is only for a quick fix +for an occasional incompatibility; +it is not a general guideline for good programming. +For good programming, +use floats where you need floats +and integers where you need integers.) +</li> + +<li> +The conversion of a float to a string now adds a <code>.0</code> suffix +to the result if it looks like an integer. +(For instance, the float 2.0 will be printed as <code>2.0</code>, +not as <code>2</code>.) +You should always use an explicit format +when you need a specific format for numbers. + + +<p> +(Formally this is not an incompatibility, +because Lua does not specify how numbers are formatted as strings, +but some programs assumed a specific format.) +</li> + +<li> +The generational mode for the garbage collector was removed. +(It was an experimental feature in Lua 5.2.) +</li> + +</ul> + + + + +<h2>8.2 – <a name="8.2">Changes in the Libraries</a></h2> +<ul> + +<li> +The <code>bit32</code> library has been deprecated. +It is easy to require a compatible external library or, +better yet, to replace its functions with appropriate bitwise operations. +(Keep in mind that <code>bit32</code> operates on 32-bit integers, +while the bitwise operators in Lua 5.3 operate on Lua integers, +which by default have 64 bits.) +</li> + +<li> +The Table library now respects metamethods +for setting and getting elements. +</li> + +<li> +The <a href="#pdf-ipairs"><code>ipairs</code></a> iterator now respects metamethods and +its <code>__ipairs</code> metamethod has been deprecated. +</li> + +<li> +Option names in <a href="#pdf-io.read"><code>io.read</code></a> do not have a starting '<code>*</code>' anymore. +For compatibility, Lua will continue to accept (and ignore) this character. +</li> + +<li> +The following functions were deprecated in the mathematical library: +<code>atan2</code>, <code>cosh</code>, <code>sinh</code>, <code>tanh</code>, <code>pow</code>, +<code>frexp</code>, and <code>ldexp</code>. +You can replace <code>math.pow(x,y)</code> with <code>x^y</code>; +you can replace <code>math.atan2</code> with <code>math.atan</code>, +which now accepts one or two arguments; +you can replace <code>math.ldexp(x,exp)</code> with <code>x * 2.0^exp</code>. +For the other operations, +you can either use an external library or +implement them in Lua. +</li> + +<li> +The searcher for C loaders used by <a href="#pdf-require"><code>require</code></a> +changed the way it handles versioned names. +Now, the version should come after the module name +(as is usual in most other tools). +For compatibility, that searcher still tries the old format +if it cannot find an open function according to the new style. +(Lua 5.2 already worked that way, +but it did not document the change.) +</li> + +<li> +The call <code>collectgarbage("count")</code> now returns only one result. +(You can compute that second result from the fractional part +of the first result.) +</li> + +</ul> + + + + +<h2>8.3 – <a name="8.3">Changes in the API</a></h2> + + +<ul> + +<li> +Continuation functions now receive as arguments what they needed +to get through <code>lua_getctx</code>, +so <code>lua_getctx</code> has been removed. +Adapt your code accordingly. +</li> + +<li> +Function <a href="#lua_dump"><code>lua_dump</code></a> has an extra parameter, <code>strip</code>. +Use 0 as the value of this parameter to get the old behavior. +</li> + +<li> +Functions to inject/project unsigned integers +(<code>lua_pushunsigned</code>, <code>lua_tounsigned</code>, <code>lua_tounsignedx</code>, +<code>luaL_checkunsigned</code>, <code>luaL_optunsigned</code>) +were deprecated. +Use their signed equivalents with a type cast. +</li> + +<li> +Macros to project non-default integer types +(<code>luaL_checkint</code>, <code>luaL_optint</code>, <code>luaL_checklong</code>, <code>luaL_optlong</code>) +were deprecated. +Use their equivalent over <a href="#lua_Integer"><code>lua_Integer</code></a> with a type cast +(or, when possible, use <a href="#lua_Integer"><code>lua_Integer</code></a> in your code). +</li> + +</ul> + + + + +<h1>9 – <a name="9">The Complete Syntax of Lua</a></h1> + +<p> +Here is the complete syntax of Lua in extended BNF. +As usual in extended BNF, +{A} means 0 or more As, +and [A] means an optional A. +(For operator precedences, see <a href="#3.4.8">§3.4.8</a>; +for a description of the terminals +Name, Numeral, +and LiteralString, see <a href="#3.1">§3.1</a>.) + + + + +<pre> + + chunk ::= block + + block ::= {stat} [retstat] + + stat ::= ‘<b>;</b>’ | + varlist ‘<b>=</b>’ explist | + functioncall | + label | + <b>break</b> | + <b>goto</b> Name | + <b>do</b> block <b>end</b> | + <b>while</b> exp <b>do</b> block <b>end</b> | + <b>repeat</b> block <b>until</b> exp | + <b>if</b> exp <b>then</b> block {<b>elseif</b> exp <b>then</b> block} [<b>else</b> block] <b>end</b> | + <b>for</b> Name ‘<b>=</b>’ exp ‘<b>,</b>’ exp [‘<b>,</b>’ exp] <b>do</b> block <b>end</b> | + <b>for</b> namelist <b>in</b> explist <b>do</b> block <b>end</b> | + <b>function</b> funcname funcbody | + <b>local</b> <b>function</b> Name funcbody | + <b>local</b> namelist [‘<b>=</b>’ explist] + + retstat ::= <b>return</b> [explist] [‘<b>;</b>’] + + label ::= ‘<b>::</b>’ Name ‘<b>::</b>’ + + funcname ::= Name {‘<b>.</b>’ Name} [‘<b>:</b>’ Name] + + varlist ::= var {‘<b>,</b>’ var} + + var ::= Name | prefixexp ‘<b>[</b>’ exp ‘<b>]</b>’ | prefixexp ‘<b>.</b>’ Name + + namelist ::= Name {‘<b>,</b>’ Name} + + explist ::= exp {‘<b>,</b>’ exp} + + exp ::= <b>nil</b> | <b>false</b> | <b>true</b> | Numeral | LiteralString | ‘<b>...</b>’ | functiondef | + prefixexp | tableconstructor | exp binop exp | unop exp + + prefixexp ::= var | functioncall | ‘<b>(</b>’ exp ‘<b>)</b>’ + + functioncall ::= prefixexp args | prefixexp ‘<b>:</b>’ Name args + + args ::= ‘<b>(</b>’ [explist] ‘<b>)</b>’ | tableconstructor | LiteralString + + functiondef ::= <b>function</b> funcbody + + funcbody ::= ‘<b>(</b>’ [parlist] ‘<b>)</b>’ block <b>end</b> + + parlist ::= namelist [‘<b>,</b>’ ‘<b>...</b>’] | ‘<b>...</b>’ + + tableconstructor ::= ‘<b>{</b>’ [fieldlist] ‘<b>}</b>’ + + fieldlist ::= field {fieldsep field} [fieldsep] + + field ::= ‘<b>[</b>’ exp ‘<b>]</b>’ ‘<b>=</b>’ exp | Name ‘<b>=</b>’ exp | exp + + fieldsep ::= ‘<b>,</b>’ | ‘<b>;</b>’ + + binop ::= ‘<b>+</b>’ | ‘<b>-</b>’ | ‘<b>*</b>’ | ‘<b>/</b>’ | ‘<b>//</b>’ | ‘<b>^</b>’ | ‘<b>%</b>’ | + ‘<b>&</b>’ | ‘<b>~</b>’ | ‘<b>|</b>’ | ‘<b>>></b>’ | ‘<b><<</b>’ | ‘<b>..</b>’ | + ‘<b><</b>’ | ‘<b><=</b>’ | ‘<b>></b>’ | ‘<b>>=</b>’ | ‘<b>==</b>’ | ‘<b>~=</b>’ | + <b>and</b> | <b>or</b> + + unop ::= ‘<b>-</b>’ | <b>not</b> | ‘<b>#</b>’ | ‘<b>~</b>’ + +</pre> + +<p> + + + + + + + + +<P CLASS="footer"> +Last update: +Tue Jul 14 10:32:39 UTC 2020 +</P> +<!-- +Last change: revised for Lua 5.3.6 +--> + +</body></html> + diff --git a/doc/osi-certified-72x60.png b/doc/osi-certified-72x60.png Binary files differnew file mode 100644 index 0000000..07df5f6 --- /dev/null +++ b/doc/osi-certified-72x60.png diff --git a/doc/readme.html b/doc/readme.html new file mode 100644 index 0000000..50716f4 --- /dev/null +++ b/doc/readme.html @@ -0,0 +1,365 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> +<HTML> +<HEAD> +<TITLE>Lua 5.3 readme</TITLE> +<LINK REL="stylesheet" TYPE="text/css" HREF="lua.css"> +<META HTTP-EQUIV="content-type" CONTENT="text/html; charset=iso-8859-1"> +<STYLE TYPE="text/css"> +blockquote, .display { + border: solid #a0a0a0 2px ; + border-radius: 8px ; + padding: 1em ; + margin: 0px ; +} + +.display { + word-spacing: 0.25em ; +} + +dl.display dd { + padding-bottom: 0.2em ; +} + +tt, kbd, code { + font-size: 12pt ; +} +</STYLE> +</HEAD> + +<BODY> + +<H1> +<A HREF="http://www.lua.org/"><IMG SRC="logo.gif" ALT="Lua"></A> +Welcome to Lua 5.3 +</H1> + +<DIV CLASS="menubar"> +<A HREF="#about">about</A> +· +<A HREF="#install">installation</A> +· +<A HREF="#changes">changes</A> +· +<A HREF="#license">license</A> +· +<A HREF="contents.html">reference manual</A> +</DIV> + +<H2><A NAME="about">About Lua</A></H2> +<P> +Lua is a powerful, fast, lightweight, embeddable scripting language +developed by a +<A HREF="http://www.lua.org/authors.html">team</A> +at +<A HREF="http://www.puc-rio.br/">PUC-Rio</A>, +the Pontifical Catholic University of Rio de Janeiro in Brazil. +Lua is +<A HREF="#license">free software</A> +used in many products and projects around the world. + +<P> +Lua's +<A HREF="http://www.lua.org/">official web site</A> +provides complete information +about Lua, +including +an +<A HREF="http://www.lua.org/about.html">executive summary</A> +and +updated +<A HREF="http://www.lua.org/docs.html">documentation</A>, +especially the +<A HREF="http://www.lua.org/manual/5.3/">reference manual</A>, +which may differ slightly from the +<A HREF="contents.html">local copy</A> +distributed in this package. + +<H2><A NAME="install">Installing Lua</A></H2> +<P> +Lua is distributed in +<A HREF="http://www.lua.org/ftp/">source</A> +form. +You need to build it before using it. +Building Lua should be straightforward +because +Lua is implemented in pure ANSI C and compiles unmodified in all known +platforms that have an ANSI C compiler. +Lua also compiles unmodified as C++. +The instructions given below for building Lua are for Unix-like platforms. +See also +<A HREF="#other">instructions for other systems</A> +and +<A HREF="#customization">customization options</A>. + +<P> +If you don't have the time or the inclination to compile Lua yourself, +get a binary from +<A HREF="http://lua-users.org/wiki/LuaBinaries">LuaBinaries</A>. +Try also +<A HREF="http://luadist.org/">LuaDist</A>, +a multi-platform distribution of Lua that includes batteries. + +<H3>Building Lua</H3> +<P> +In most Unix-like platforms, simply do "<KBD>make</KBD>" with a suitable target. +Here are the details. + +<OL> +<LI> +Open a terminal window and move to +the top-level directory, which is named <TT>lua-5.3.6</TT>. +The <TT>Makefile</TT> there controls both the build process and the installation process. +<P> +<LI> + Do "<KBD>make</KBD>" and see if your platform is listed. + The platforms currently supported are: +<P> +<P CLASS="display"> + aix bsd c89 freebsd generic linux macosx mingw posix solaris +</P> +<P> + If your platform is listed, just do "<KBD>make xxx</KBD>", where xxx + is your platform name. +<P> + If your platform is not listed, try the closest one or posix, generic, + c89, in this order. +<P> +<LI> +The compilation takes only a few moments +and produces three files in the <TT>src</TT> directory: +lua (the interpreter), +luac (the compiler), +and liblua.a (the library). +<P> +<LI> + To check that Lua has been built correctly, do "<KBD>make test</KBD>" + after building Lua. This will run the interpreter and print its version. +</OL> +<P> +If you're running Linux and get compilation errors, +make sure you have installed the <TT>readline</TT> development package +(which is probably named <TT>libreadline-dev</TT> or <TT>readline-devel</TT>). +If you get link errors after that, +then try "<KBD>make linux MYLIBS=-ltermcap</KBD>". + +<H3>Installing Lua</H3> +<P> + Once you have built Lua, you may want to install it in an official + place in your system. In this case, do "<KBD>make install</KBD>". The official + place and the way to install files are defined in the <TT>Makefile</TT>. You'll + probably need the right permissions to install files. + +<P> + To build and install Lua in one step, do "<KBD>make xxx install</KBD>", + where xxx is your platform name. + +<P> + To install Lua locally, do "<KBD>make local</KBD>". + This will create a directory <TT>install</TT> with subdirectories + <TT>bin</TT>, <TT>include</TT>, <TT>lib</TT>, <TT>man</TT>, <TT>share</TT>, + and install Lua as listed below. + + To install Lua locally, but in some other directory, do + "<KBD>make install INSTALL_TOP=xxx</KBD>", where xxx is your chosen directory. + The installation starts in the <TT>src</TT> and <TT>doc</TT> directories, + so take care if <TT>INSTALL_TOP</TT> is not an absolute path. + +<DL CLASS="display"> +<DT> + bin: +<DD> + lua luac +<DT> + include: +<DD> + lua.h luaconf.h lualib.h lauxlib.h lua.hpp +<DT> + lib: +<DD> + liblua.a +<DT> + man/man1: +<DD> + lua.1 luac.1 +</DL> + +<P> + These are the only directories you need for development. + If you only want to run Lua programs, + you only need the files in <TT>bin</TT> and <TT>man</TT>. + The files in <TT>include</TT> and <TT>lib</TT> are needed for + embedding Lua in C or C++ programs. + +<H3><A NAME="customization">Customization</A></H3> +<P> + Three kinds of things can be customized by editing a file: +<UL> + <LI> Where and how to install Lua — edit <TT>Makefile</TT>. + <LI> How to build Lua — edit <TT>src/Makefile</TT>. + <LI> Lua features — edit <TT>src/luaconf.h</TT>. +</UL> + +<P> + You don't actually need to edit the Makefiles because you may set the + relevant variables in the command line when invoking make. + Nevertheless, it's probably best to edit and save the Makefiles to + record the changes you've made. + +<P> + On the other hand, if you need to customize some Lua features, you'll need + to edit <TT>src/luaconf.h</TT> before building and installing Lua. + The edited file will be the one installed, and + it will be used by any Lua clients that you build, to ensure consistency. + Further customization is available to experts by editing the Lua sources. + +<H3><A NAME="other">Building Lua on other systems</A></H3> +<P> + If you're not using the usual Unix tools, then the instructions for + building Lua depend on the compiler you use. You'll need to create + projects (or whatever your compiler uses) for building the library, + the interpreter, and the compiler, as follows: + +<DL CLASS="display"> +<DT> +library: +<DD> +lapi.c lcode.c lctype.c ldebug.c ldo.c ldump.c lfunc.c lgc.c llex.c +lmem.c lobject.c lopcodes.c lparser.c lstate.c lstring.c ltable.c +ltm.c lundump.c lvm.c lzio.c +lauxlib.c lbaselib.c lbitlib.c lcorolib.c ldblib.c liolib.c +lmathlib.c loslib.c lstrlib.c ltablib.c lutf8lib.c loadlib.c linit.c +<DT> +interpreter: +<DD> + library, lua.c +<DT> +compiler: +<DD> + library, luac.c +</DL> + +<P> + To use Lua as a library in your own programs you'll need to know how to + create and use libraries with your compiler. Moreover, to dynamically load + C libraries for Lua you'll need to know how to create dynamic libraries + and you'll need to make sure that the Lua API functions are accessible to + those dynamic libraries — but <EM>don't</EM> link the Lua library + into each dynamic library. For Unix, we recommend that the Lua library + be linked statically into the host program and its symbols exported for + dynamic linking; <TT>src/Makefile</TT> does this for the Lua interpreter. + For Windows, we recommend that the Lua library be a DLL. + In all cases, the compiler luac should be linked statically. + +<P> + As mentioned above, you may edit <TT>src/luaconf.h</TT> to customize + some features before building Lua. + +<H2><A NAME="changes">Changes since Lua 5.2</A></H2> +<P> +Here are the main changes introduced in Lua 5.3. +The +<A HREF="contents.html">reference manual</A> +lists the +<A HREF="manual.html#8">incompatibilities</A> that had to be introduced. + +<H3>Main changes</H3> +<UL> +<LI> integers (64-bit by default) +<LI> official support for 32-bit numbers +<LI> bitwise operators +<LI> basic utf-8 support +<LI> functions for packing and unpacking values + +</UL> + +Here are the other changes introduced in Lua 5.3: +<H3>Language</H3> +<UL> +<LI> userdata can have any Lua value as uservalue +<LI> floor division +<LI> more flexible rules for some metamethods +</UL> + +<H3>Libraries</H3> +<UL> +<LI> <CODE>ipairs</CODE> and the table library respect metamethods +<LI> strip option in <CODE>string.dump</CODE> +<LI> table library respects metamethods +<LI> new function <CODE>table.move</CODE> +<LI> new function <CODE>string.pack</CODE> +<LI> new function <CODE>string.unpack</CODE> +<LI> new function <CODE>string.packsize</CODE> +</UL> + +<H3>C API</H3> +<UL> +<LI> simpler API for continuation functions in C +<LI> <CODE>lua_gettable</CODE> and similar functions return type of resulted value +<LI> strip option in <CODE>lua_dump</CODE> +<LI> new function: <CODE>lua_geti</CODE> +<LI> new function: <CODE>lua_seti</CODE> +<LI> new function: <CODE>lua_isyieldable</CODE> +<LI> new function: <CODE>lua_numbertointeger</CODE> +<LI> new function: <CODE>lua_rotate</CODE> +<LI> new function: <CODE>lua_stringtonumber</CODE> +</UL> + +<H3>Lua standalone interpreter</H3> +<UL> +<LI> can be used as calculator; no need to prefix with '=' +<LI> <CODE>arg</CODE> table available to all code +</UL> + +<H2><A NAME="license">License</A></H2> +<P> +<A HREF="http://www.opensource.org/docs/definition.php"> +<IMG SRC="osi-certified-72x60.png" ALIGN="right" ALT="[osi certified]" STYLE="padding-left: 30px ;"> +</A> +Lua is free software distributed under the terms of the +<A HREF="http://www.opensource.org/licenses/mit-license.html">MIT license</A> +reproduced below; +it may be used for any purpose, including commercial purposes, +at absolutely no cost without having to ask us. + +The only requirement is that if you do use Lua, +then you should give us credit by including the appropriate copyright notice somewhere in your product or its documentation. + +For details, see +<A HREF="http://www.lua.org/license.html">this</A>. + +<BLOCKQUOTE STYLE="padding-bottom: 0em"> +Copyright © 1994–2020 Lua.org, PUC-Rio. + +<P> +Permission is hereby granted, free of charge, to any person obtaining a copy +of this software and associated documentation files (the "Software"), to deal +in the Software without restriction, including without limitation the rights +to use, copy, modify, merge, publish, distribute, sublicense, and/or sell +copies of the Software, and to permit persons to whom the Software is +furnished to do so, subject to the following conditions: + +<P> +The above copyright notice and this permission notice shall be included in +all copies or substantial portions of the Software. + +<P> +THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR +IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, +FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE +AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER +LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, +OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN +THE SOFTWARE. +</BLOCKQUOTE> +<P> + +<P CLASS="footer"> +Last update: +Tue Jul 14 10:33:01 UTC 2020 +</P> +<!-- +Last change: revised for Lua 5.3.6 +--> + +</BODY> +</HTML> diff --git a/src/Makefile b/src/Makefile new file mode 100644 index 0000000..a13afb9 --- /dev/null +++ b/src/Makefile @@ -0,0 +1,197 @@ +# Makefile for building Lua +# See ../doc/readme.html for installation and customization instructions. + +# == CHANGE THE SETTINGS BELOW TO SUIT YOUR ENVIRONMENT ======================= + +# Your platform. See PLATS for possible values. +PLAT= none + +CC= gcc -std=gnu99 +CFLAGS= -O2 -Wall -Wextra -DLUA_COMPAT_5_2 $(SYSCFLAGS) $(MYCFLAGS) +LDFLAGS= $(SYSLDFLAGS) $(MYLDFLAGS) +LIBS= -lm $(SYSLIBS) $(MYLIBS) + +AR= ar rcu +RANLIB= ranlib +RM= rm -f + +SYSCFLAGS= +SYSLDFLAGS= +SYSLIBS= + +MYCFLAGS= +MYLDFLAGS= +MYLIBS= +MYOBJS= + +# == END OF USER SETTINGS -- NO NEED TO CHANGE ANYTHING BELOW THIS LINE ======= + +PLATS= aix bsd c89 freebsd generic linux macosx mingw posix solaris + +LUA_A= liblua.a +CORE_O= lapi.o lcode.o lctype.o ldebug.o ldo.o ldump.o lfunc.o lgc.o llex.o \ + lmem.o lobject.o lopcodes.o lparser.o lstate.o lstring.o ltable.o \ + ltm.o lundump.o lvm.o lzio.o +LIB_O= lauxlib.o lbaselib.o lbitlib.o lcorolib.o ldblib.o liolib.o \ + lmathlib.o loslib.o lstrlib.o ltablib.o lutf8lib.o loadlib.o linit.o +BASE_O= $(CORE_O) $(LIB_O) $(MYOBJS) + +LUA_T= lua +LUA_O= lua.o + +LUAC_T= luac +LUAC_O= luac.o + +ALL_O= $(BASE_O) $(LUA_O) $(LUAC_O) +ALL_T= $(LUA_A) $(LUA_T) $(LUAC_T) +ALL_A= $(LUA_A) + +# Targets start here. +default: $(PLAT) + +all: $(ALL_T) + +o: $(ALL_O) + +a: $(ALL_A) + +$(LUA_A): $(BASE_O) + $(AR) $@ $(BASE_O) + $(RANLIB) $@ + +$(LUA_T): $(LUA_O) $(LUA_A) + $(CC) -o $@ $(LDFLAGS) $(LUA_O) $(LUA_A) $(LIBS) + +$(LUAC_T): $(LUAC_O) $(LUA_A) + $(CC) -o $@ $(LDFLAGS) $(LUAC_O) $(LUA_A) $(LIBS) + +clean: + $(RM) $(ALL_T) $(ALL_O) + +depend: + @$(CC) $(CFLAGS) -MM l*.c + +echo: + @echo "PLAT= $(PLAT)" + @echo "CC= $(CC)" + @echo "CFLAGS= $(CFLAGS)" + @echo "LDFLAGS= $(SYSLDFLAGS)" + @echo "LIBS= $(LIBS)" + @echo "AR= $(AR)" + @echo "RANLIB= $(RANLIB)" + @echo "RM= $(RM)" + +# Convenience targets for popular platforms +ALL= all + +none: + @echo "Please do 'make PLATFORM' where PLATFORM is one of these:" + @echo " $(PLATS)" + +aix: + $(MAKE) $(ALL) CC="xlc" CFLAGS="-O2 -DLUA_USE_POSIX -DLUA_USE_DLOPEN" SYSLIBS="-ldl" SYSLDFLAGS="-brtl -bexpall" + +bsd: + $(MAKE) $(ALL) SYSCFLAGS="-DLUA_USE_POSIX -DLUA_USE_DLOPEN" SYSLIBS="-Wl,-E" + +c89: + $(MAKE) $(ALL) SYSCFLAGS="-DLUA_USE_C89" CC="gcc -std=c89" + @echo '' + @echo '*** C89 does not guarantee 64-bit integers for Lua.' + @echo '' + + +freebsd: + $(MAKE) $(ALL) SYSCFLAGS="-DLUA_USE_LINUX -I/usr/include/edit" SYSLIBS="-Wl,-E -ledit" CC="cc" + +generic: $(ALL) + +linux: + $(MAKE) $(ALL) SYSCFLAGS="-DLUA_USE_LINUX" SYSLIBS="-Wl,-E -ldl -lreadline" + +macosx: + $(MAKE) $(ALL) SYSCFLAGS="-DLUA_USE_MACOSX" SYSLIBS="-lreadline" + +mingw: + $(MAKE) "LUA_A=lua53.dll" "LUA_T=lua.exe" \ + "AR=$(CC) -shared -o" "RANLIB=strip --strip-unneeded" \ + "SYSCFLAGS=-DLUA_BUILD_AS_DLL" "SYSLIBS=" "SYSLDFLAGS=-s" lua.exe + $(MAKE) "LUAC_T=luac.exe" luac.exe + +posix: + $(MAKE) $(ALL) SYSCFLAGS="-DLUA_USE_POSIX" + +solaris: + $(MAKE) $(ALL) SYSCFLAGS="-DLUA_USE_POSIX -DLUA_USE_DLOPEN -D_REENTRANT" SYSLIBS="-ldl" + +# list targets that do not create files (but not all makes understand .PHONY) +.PHONY: all $(PLATS) default o a clean depend echo none + +# DO NOT DELETE + +lapi.o: lapi.c lprefix.h lua.h luaconf.h lapi.h llimits.h lstate.h \ + lobject.h ltm.h lzio.h lmem.h ldebug.h ldo.h lfunc.h lgc.h lstring.h \ + ltable.h lundump.h lvm.h +lauxlib.o: lauxlib.c lprefix.h lua.h luaconf.h lauxlib.h +lbaselib.o: lbaselib.c lprefix.h lua.h luaconf.h lauxlib.h lualib.h +lbitlib.o: lbitlib.c lprefix.h lua.h luaconf.h lauxlib.h lualib.h +lcode.o: lcode.c lprefix.h lua.h luaconf.h lcode.h llex.h lobject.h \ + llimits.h lzio.h lmem.h lopcodes.h lparser.h ldebug.h lstate.h ltm.h \ + ldo.h lgc.h lstring.h ltable.h lvm.h +lcorolib.o: lcorolib.c lprefix.h lua.h luaconf.h lauxlib.h lualib.h +lctype.o: lctype.c lprefix.h lctype.h lua.h luaconf.h llimits.h +ldblib.o: ldblib.c lprefix.h lua.h luaconf.h lauxlib.h lualib.h +ldebug.o: ldebug.c lprefix.h lua.h luaconf.h lapi.h llimits.h lstate.h \ + lobject.h ltm.h lzio.h lmem.h lcode.h llex.h lopcodes.h lparser.h \ + ldebug.h ldo.h lfunc.h lstring.h lgc.h ltable.h lvm.h +ldo.o: ldo.c lprefix.h lua.h luaconf.h lapi.h llimits.h lstate.h \ + lobject.h ltm.h lzio.h lmem.h ldebug.h ldo.h lfunc.h lgc.h lopcodes.h \ + lparser.h lstring.h ltable.h lundump.h lvm.h +ldump.o: ldump.c lprefix.h lua.h luaconf.h lobject.h llimits.h lstate.h \ + ltm.h lzio.h lmem.h lundump.h +lfunc.o: lfunc.c lprefix.h lua.h luaconf.h lfunc.h lobject.h llimits.h \ + lgc.h lstate.h ltm.h lzio.h lmem.h +lgc.o: lgc.c lprefix.h lua.h luaconf.h ldebug.h lstate.h lobject.h \ + llimits.h ltm.h lzio.h lmem.h ldo.h lfunc.h lgc.h lstring.h ltable.h +linit.o: linit.c lprefix.h lua.h luaconf.h lualib.h lauxlib.h +liolib.o: liolib.c lprefix.h lua.h luaconf.h lauxlib.h lualib.h +llex.o: llex.c lprefix.h lua.h luaconf.h lctype.h llimits.h ldebug.h \ + lstate.h lobject.h ltm.h lzio.h lmem.h ldo.h lgc.h llex.h lparser.h \ + lstring.h ltable.h +lmathlib.o: lmathlib.c lprefix.h lua.h luaconf.h lauxlib.h lualib.h +lmem.o: lmem.c lprefix.h lua.h luaconf.h ldebug.h lstate.h lobject.h \ + llimits.h ltm.h lzio.h lmem.h ldo.h lgc.h +loadlib.o: loadlib.c lprefix.h lua.h luaconf.h lauxlib.h lualib.h +lobject.o: lobject.c lprefix.h lua.h luaconf.h lctype.h llimits.h \ + ldebug.h lstate.h lobject.h ltm.h lzio.h lmem.h ldo.h lstring.h lgc.h \ + lvm.h +lopcodes.o: lopcodes.c lprefix.h lopcodes.h llimits.h lua.h luaconf.h +loslib.o: loslib.c lprefix.h lua.h luaconf.h lauxlib.h lualib.h +lparser.o: lparser.c lprefix.h lua.h luaconf.h lcode.h llex.h lobject.h \ + llimits.h lzio.h lmem.h lopcodes.h lparser.h ldebug.h lstate.h ltm.h \ + ldo.h lfunc.h lstring.h lgc.h ltable.h +lstate.o: lstate.c lprefix.h lua.h luaconf.h lapi.h llimits.h lstate.h \ + lobject.h ltm.h lzio.h lmem.h ldebug.h ldo.h lfunc.h lgc.h llex.h \ + lstring.h ltable.h +lstring.o: lstring.c lprefix.h lua.h luaconf.h ldebug.h lstate.h \ + lobject.h llimits.h ltm.h lzio.h lmem.h ldo.h lstring.h lgc.h +lstrlib.o: lstrlib.c lprefix.h lua.h luaconf.h lauxlib.h lualib.h +ltable.o: ltable.c lprefix.h lua.h luaconf.h ldebug.h lstate.h lobject.h \ + llimits.h ltm.h lzio.h lmem.h ldo.h lgc.h lstring.h ltable.h lvm.h +ltablib.o: ltablib.c lprefix.h lua.h luaconf.h lauxlib.h lualib.h +ltm.o: ltm.c lprefix.h lua.h luaconf.h ldebug.h lstate.h lobject.h \ + llimits.h ltm.h lzio.h lmem.h ldo.h lstring.h lgc.h ltable.h lvm.h +lua.o: lua.c lprefix.h lua.h luaconf.h lauxlib.h lualib.h +luac.o: luac.c lprefix.h lua.h luaconf.h lauxlib.h lobject.h llimits.h \ + lstate.h ltm.h lzio.h lmem.h lundump.h ldebug.h lopcodes.h +lundump.o: lundump.c lprefix.h lua.h luaconf.h ldebug.h lstate.h \ + lobject.h llimits.h ltm.h lzio.h lmem.h ldo.h lfunc.h lstring.h lgc.h \ + lundump.h +lutf8lib.o: lutf8lib.c lprefix.h lua.h luaconf.h lauxlib.h lualib.h +lvm.o: lvm.c lprefix.h lua.h luaconf.h ldebug.h lstate.h lobject.h \ + llimits.h ltm.h lzio.h lmem.h ldo.h lfunc.h lgc.h lopcodes.h lstring.h \ + ltable.h lvm.h +lzio.o: lzio.c lprefix.h lua.h luaconf.h llimits.h lmem.h lstate.h \ + lobject.h ltm.h lzio.h + +# (end of Makefile) diff --git a/src/lapi.c b/src/lapi.c new file mode 100644 index 0000000..711895b --- /dev/null +++ b/src/lapi.c @@ -0,0 +1,1299 @@ +/* +** $Id: lapi.c,v 2.259.1.2 2017/12/06 18:35:12 roberto Exp $ +** Lua API +** See Copyright Notice in lua.h +*/ + +#define lapi_c +#define LUA_CORE + +#include "lprefix.h" + + +#include <stdarg.h> +#include <string.h> + +#include "lua.h" + +#include "lapi.h" +#include "ldebug.h" +#include "ldo.h" +#include "lfunc.h" +#include "lgc.h" +#include "lmem.h" +#include "lobject.h" +#include "lstate.h" +#include "lstring.h" +#include "ltable.h" +#include "ltm.h" +#include "lundump.h" +#include "lvm.h" + + + +const char lua_ident[] = + "$LuaVersion: " LUA_COPYRIGHT " $" + "$LuaAuthors: " LUA_AUTHORS " $"; + + +/* value at a non-valid index */ +#define NONVALIDVALUE cast(TValue *, luaO_nilobject) + +/* corresponding test */ +#define isvalid(o) ((o) != luaO_nilobject) + +/* test for pseudo index */ +#define ispseudo(i) ((i) <= LUA_REGISTRYINDEX) + +/* test for upvalue */ +#define isupvalue(i) ((i) < LUA_REGISTRYINDEX) + +/* test for valid but not pseudo index */ +#define isstackindex(i, o) (isvalid(o) && !ispseudo(i)) + +#define api_checkvalidindex(l,o) api_check(l, isvalid(o), "invalid index") + +#define api_checkstackindex(l, i, o) \ + api_check(l, isstackindex(i, o), "index not in the stack") + + +static TValue *index2addr (lua_State *L, int idx) { + CallInfo *ci = L->ci; + if (idx > 0) { + TValue *o = ci->func + idx; + api_check(L, idx <= ci->top - (ci->func + 1), "unacceptable index"); + if (o >= L->top) return NONVALIDVALUE; + else return o; + } + else if (!ispseudo(idx)) { /* negative index */ + api_check(L, idx != 0 && -idx <= L->top - (ci->func + 1), "invalid index"); + return L->top + idx; + } + else if (idx == LUA_REGISTRYINDEX) + return &G(L)->l_registry; + else { /* upvalues */ + idx = LUA_REGISTRYINDEX - idx; + api_check(L, idx <= MAXUPVAL + 1, "upvalue index too large"); + if (ttislcf(ci->func)) /* light C function? */ + return NONVALIDVALUE; /* it has no upvalues */ + else { + CClosure *func = clCvalue(ci->func); + return (idx <= func->nupvalues) ? &func->upvalue[idx-1] : NONVALIDVALUE; + } + } +} + + +/* +** to be called by 'lua_checkstack' in protected mode, to grow stack +** capturing memory errors +*/ +static void growstack (lua_State *L, void *ud) { + int size = *(int *)ud; + luaD_growstack(L, size); +} + + +LUA_API int lua_checkstack (lua_State *L, int n) { + int res; + CallInfo *ci = L->ci; + lua_lock(L); + api_check(L, n >= 0, "negative 'n'"); + if (L->stack_last - L->top > n) /* stack large enough? */ + res = 1; /* yes; check is OK */ + else { /* no; need to grow stack */ + int inuse = cast_int(L->top - L->stack) + EXTRA_STACK; + if (inuse > LUAI_MAXSTACK - n) /* can grow without overflow? */ + res = 0; /* no */ + else /* try to grow stack */ + res = (luaD_rawrunprotected(L, &growstack, &n) == LUA_OK); + } + if (res && ci->top < L->top + n) + ci->top = L->top + n; /* adjust frame top */ + lua_unlock(L); + return res; +} + + +LUA_API void lua_xmove (lua_State *from, lua_State *to, int n) { + int i; + if (from == to) return; + lua_lock(to); + api_checknelems(from, n); + api_check(from, G(from) == G(to), "moving among independent states"); + api_check(from, to->ci->top - to->top >= n, "stack overflow"); + from->top -= n; + for (i = 0; i < n; i++) { + setobj2s(to, to->top, from->top + i); + to->top++; /* stack already checked by previous 'api_check' */ + } + lua_unlock(to); +} + + +LUA_API lua_CFunction lua_atpanic (lua_State *L, lua_CFunction panicf) { + lua_CFunction old; + lua_lock(L); + old = G(L)->panic; + G(L)->panic = panicf; + lua_unlock(L); + return old; +} + + +LUA_API const lua_Number *lua_version (lua_State *L) { + static const lua_Number version = LUA_VERSION_NUM; + if (L == NULL) return &version; + else return G(L)->version; +} + + + +/* +** basic stack manipulation +*/ + + +/* +** convert an acceptable stack index into an absolute index +*/ +LUA_API int lua_absindex (lua_State *L, int idx) { + return (idx > 0 || ispseudo(idx)) + ? idx + : cast_int(L->top - L->ci->func) + idx; +} + + +LUA_API int lua_gettop (lua_State *L) { + return cast_int(L->top - (L->ci->func + 1)); +} + + +LUA_API void lua_settop (lua_State *L, int idx) { + StkId func = L->ci->func; + lua_lock(L); + if (idx >= 0) { + api_check(L, idx <= L->stack_last - (func + 1), "new top too large"); + while (L->top < (func + 1) + idx) + setnilvalue(L->top++); + L->top = (func + 1) + idx; + } + else { + api_check(L, -(idx+1) <= (L->top - (func + 1)), "invalid new top"); + L->top += idx+1; /* 'subtract' index (index is negative) */ + } + lua_unlock(L); +} + + +/* +** Reverse the stack segment from 'from' to 'to' +** (auxiliary to 'lua_rotate') +*/ +static void reverse (lua_State *L, StkId from, StkId to) { + for (; from < to; from++, to--) { + TValue temp; + setobj(L, &temp, from); + setobjs2s(L, from, to); + setobj2s(L, to, &temp); + } +} + + +/* +** Let x = AB, where A is a prefix of length 'n'. Then, +** rotate x n == BA. But BA == (A^r . B^r)^r. +*/ +LUA_API void lua_rotate (lua_State *L, int idx, int n) { + StkId p, t, m; + lua_lock(L); + t = L->top - 1; /* end of stack segment being rotated */ + p = index2addr(L, idx); /* start of segment */ + api_checkstackindex(L, idx, p); + api_check(L, (n >= 0 ? n : -n) <= (t - p + 1), "invalid 'n'"); + m = (n >= 0 ? t - n : p - n - 1); /* end of prefix */ + reverse(L, p, m); /* reverse the prefix with length 'n' */ + reverse(L, m + 1, t); /* reverse the suffix */ + reverse(L, p, t); /* reverse the entire segment */ + lua_unlock(L); +} + + +LUA_API void lua_copy (lua_State *L, int fromidx, int toidx) { + TValue *fr, *to; + lua_lock(L); + fr = index2addr(L, fromidx); + to = index2addr(L, toidx); + api_checkvalidindex(L, to); + setobj(L, to, fr); + if (isupvalue(toidx)) /* function upvalue? */ + luaC_barrier(L, clCvalue(L->ci->func), fr); + /* LUA_REGISTRYINDEX does not need gc barrier + (collector revisits it before finishing collection) */ + lua_unlock(L); +} + + +LUA_API void lua_pushvalue (lua_State *L, int idx) { + lua_lock(L); + setobj2s(L, L->top, index2addr(L, idx)); + api_incr_top(L); + lua_unlock(L); +} + + + +/* +** access functions (stack -> C) +*/ + + +LUA_API int lua_type (lua_State *L, int idx) { + StkId o = index2addr(L, idx); + return (isvalid(o) ? ttnov(o) : LUA_TNONE); +} + + +LUA_API const char *lua_typename (lua_State *L, int t) { + UNUSED(L); + api_check(L, LUA_TNONE <= t && t < LUA_NUMTAGS, "invalid tag"); + return ttypename(t); +} + + +LUA_API int lua_iscfunction (lua_State *L, int idx) { + StkId o = index2addr(L, idx); + return (ttislcf(o) || (ttisCclosure(o))); +} + + +LUA_API int lua_isinteger (lua_State *L, int idx) { + StkId o = index2addr(L, idx); + return ttisinteger(o); +} + + +LUA_API int lua_isnumber (lua_State *L, int idx) { + lua_Number n; + const TValue *o = index2addr(L, idx); + return tonumber(o, &n); +} + + +LUA_API int lua_isstring (lua_State *L, int idx) { + const TValue *o = index2addr(L, idx); + return (ttisstring(o) || cvt2str(o)); +} + + +LUA_API int lua_isuserdata (lua_State *L, int idx) { + const TValue *o = index2addr(L, idx); + return (ttisfulluserdata(o) || ttislightuserdata(o)); +} + + +LUA_API int lua_rawequal (lua_State *L, int index1, int index2) { + StkId o1 = index2addr(L, index1); + StkId o2 = index2addr(L, index2); + return (isvalid(o1) && isvalid(o2)) ? luaV_rawequalobj(o1, o2) : 0; +} + + +LUA_API void lua_arith (lua_State *L, int op) { + lua_lock(L); + if (op != LUA_OPUNM && op != LUA_OPBNOT) + api_checknelems(L, 2); /* all other operations expect two operands */ + else { /* for unary operations, add fake 2nd operand */ + api_checknelems(L, 1); + setobjs2s(L, L->top, L->top - 1); + api_incr_top(L); + } + /* first operand at top - 2, second at top - 1; result go to top - 2 */ + luaO_arith(L, op, L->top - 2, L->top - 1, L->top - 2); + L->top--; /* remove second operand */ + lua_unlock(L); +} + + +LUA_API int lua_compare (lua_State *L, int index1, int index2, int op) { + StkId o1, o2; + int i = 0; + lua_lock(L); /* may call tag method */ + o1 = index2addr(L, index1); + o2 = index2addr(L, index2); + if (isvalid(o1) && isvalid(o2)) { + switch (op) { + case LUA_OPEQ: i = luaV_equalobj(L, o1, o2); break; + case LUA_OPLT: i = luaV_lessthan(L, o1, o2); break; + case LUA_OPLE: i = luaV_lessequal(L, o1, o2); break; + default: api_check(L, 0, "invalid option"); + } + } + lua_unlock(L); + return i; +} + + +LUA_API size_t lua_stringtonumber (lua_State *L, const char *s) { + size_t sz = luaO_str2num(s, L->top); + if (sz != 0) + api_incr_top(L); + return sz; +} + + +LUA_API lua_Number lua_tonumberx (lua_State *L, int idx, int *pisnum) { + lua_Number n; + const TValue *o = index2addr(L, idx); + int isnum = tonumber(o, &n); + if (!isnum) + n = 0; /* call to 'tonumber' may change 'n' even if it fails */ + if (pisnum) *pisnum = isnum; + return n; +} + + +LUA_API lua_Integer lua_tointegerx (lua_State *L, int idx, int *pisnum) { + lua_Integer res; + const TValue *o = index2addr(L, idx); + int isnum = tointeger(o, &res); + if (!isnum) + res = 0; /* call to 'tointeger' may change 'n' even if it fails */ + if (pisnum) *pisnum = isnum; + return res; +} + + +LUA_API int lua_toboolean (lua_State *L, int idx) { + const TValue *o = index2addr(L, idx); + return !l_isfalse(o); +} + + +LUA_API const char *lua_tolstring (lua_State *L, int idx, size_t *len) { + StkId o = index2addr(L, idx); + if (!ttisstring(o)) { + if (!cvt2str(o)) { /* not convertible? */ + if (len != NULL) *len = 0; + return NULL; + } + lua_lock(L); /* 'luaO_tostring' may create a new string */ + luaO_tostring(L, o); + luaC_checkGC(L); + o = index2addr(L, idx); /* previous call may reallocate the stack */ + lua_unlock(L); + } + if (len != NULL) + *len = vslen(o); + return svalue(o); +} + + +LUA_API size_t lua_rawlen (lua_State *L, int idx) { + StkId o = index2addr(L, idx); + switch (ttype(o)) { + case LUA_TSHRSTR: return tsvalue(o)->shrlen; + case LUA_TLNGSTR: return tsvalue(o)->u.lnglen; + case LUA_TUSERDATA: return uvalue(o)->len; + case LUA_TTABLE: return luaH_getn(hvalue(o)); + default: return 0; + } +} + + +LUA_API lua_CFunction lua_tocfunction (lua_State *L, int idx) { + StkId o = index2addr(L, idx); + if (ttislcf(o)) return fvalue(o); + else if (ttisCclosure(o)) + return clCvalue(o)->f; + else return NULL; /* not a C function */ +} + + +LUA_API void *lua_touserdata (lua_State *L, int idx) { + StkId o = index2addr(L, idx); + switch (ttnov(o)) { + case LUA_TUSERDATA: return getudatamem(uvalue(o)); + case LUA_TLIGHTUSERDATA: return pvalue(o); + default: return NULL; + } +} + + +LUA_API lua_State *lua_tothread (lua_State *L, int idx) { + StkId o = index2addr(L, idx); + return (!ttisthread(o)) ? NULL : thvalue(o); +} + + +LUA_API const void *lua_topointer (lua_State *L, int idx) { + StkId o = index2addr(L, idx); + switch (ttype(o)) { + case LUA_TTABLE: return hvalue(o); + case LUA_TLCL: return clLvalue(o); + case LUA_TCCL: return clCvalue(o); + case LUA_TLCF: return cast(void *, cast(size_t, fvalue(o))); + case LUA_TTHREAD: return thvalue(o); + case LUA_TUSERDATA: return getudatamem(uvalue(o)); + case LUA_TLIGHTUSERDATA: return pvalue(o); + default: return NULL; + } +} + + + +/* +** push functions (C -> stack) +*/ + + +LUA_API void lua_pushnil (lua_State *L) { + lua_lock(L); + setnilvalue(L->top); + api_incr_top(L); + lua_unlock(L); +} + + +LUA_API void lua_pushnumber (lua_State *L, lua_Number n) { + lua_lock(L); + setfltvalue(L->top, n); + api_incr_top(L); + lua_unlock(L); +} + + +LUA_API void lua_pushinteger (lua_State *L, lua_Integer n) { + lua_lock(L); + setivalue(L->top, n); + api_incr_top(L); + lua_unlock(L); +} + + +/* +** Pushes on the stack a string with given length. Avoid using 's' when +** 'len' == 0 (as 's' can be NULL in that case), due to later use of +** 'memcmp' and 'memcpy'. +*/ +LUA_API const char *lua_pushlstring (lua_State *L, const char *s, size_t len) { + TString *ts; + lua_lock(L); + ts = (len == 0) ? luaS_new(L, "") : luaS_newlstr(L, s, len); + setsvalue2s(L, L->top, ts); + api_incr_top(L); + luaC_checkGC(L); + lua_unlock(L); + return getstr(ts); +} + + +LUA_API const char *lua_pushstring (lua_State *L, const char *s) { + lua_lock(L); + if (s == NULL) + setnilvalue(L->top); + else { + TString *ts; + ts = luaS_new(L, s); + setsvalue2s(L, L->top, ts); + s = getstr(ts); /* internal copy's address */ + } + api_incr_top(L); + luaC_checkGC(L); + lua_unlock(L); + return s; +} + + +LUA_API const char *lua_pushvfstring (lua_State *L, const char *fmt, + va_list argp) { + const char *ret; + lua_lock(L); + ret = luaO_pushvfstring(L, fmt, argp); + luaC_checkGC(L); + lua_unlock(L); + return ret; +} + + +LUA_API const char *lua_pushfstring (lua_State *L, const char *fmt, ...) { + const char *ret; + va_list argp; + lua_lock(L); + va_start(argp, fmt); + ret = luaO_pushvfstring(L, fmt, argp); + va_end(argp); + luaC_checkGC(L); + lua_unlock(L); + return ret; +} + + +LUA_API void lua_pushcclosure (lua_State *L, lua_CFunction fn, int n) { + lua_lock(L); + if (n == 0) { + setfvalue(L->top, fn); + api_incr_top(L); + } + else { + CClosure *cl; + api_checknelems(L, n); + api_check(L, n <= MAXUPVAL, "upvalue index too large"); + cl = luaF_newCclosure(L, n); + cl->f = fn; + L->top -= n; + while (n--) { + setobj2n(L, &cl->upvalue[n], L->top + n); + /* does not need barrier because closure is white */ + } + setclCvalue(L, L->top, cl); + api_incr_top(L); + luaC_checkGC(L); + } + lua_unlock(L); +} + + +LUA_API void lua_pushboolean (lua_State *L, int b) { + lua_lock(L); + setbvalue(L->top, (b != 0)); /* ensure that true is 1 */ + api_incr_top(L); + lua_unlock(L); +} + + +LUA_API void lua_pushlightuserdata (lua_State *L, void *p) { + lua_lock(L); + setpvalue(L->top, p); + api_incr_top(L); + lua_unlock(L); +} + + +LUA_API int lua_pushthread (lua_State *L) { + lua_lock(L); + setthvalue(L, L->top, L); + api_incr_top(L); + lua_unlock(L); + return (G(L)->mainthread == L); +} + + + +/* +** get functions (Lua -> stack) +*/ + + +static int auxgetstr (lua_State *L, const TValue *t, const char *k) { + const TValue *slot; + TString *str = luaS_new(L, k); + if (luaV_fastget(L, t, str, slot, luaH_getstr)) { + setobj2s(L, L->top, slot); + api_incr_top(L); + } + else { + setsvalue2s(L, L->top, str); + api_incr_top(L); + luaV_finishget(L, t, L->top - 1, L->top - 1, slot); + } + lua_unlock(L); + return ttnov(L->top - 1); +} + + +LUA_API int lua_getglobal (lua_State *L, const char *name) { + Table *reg = hvalue(&G(L)->l_registry); + lua_lock(L); + return auxgetstr(L, luaH_getint(reg, LUA_RIDX_GLOBALS), name); +} + + +LUA_API int lua_gettable (lua_State *L, int idx) { + StkId t; + lua_lock(L); + t = index2addr(L, idx); + luaV_gettable(L, t, L->top - 1, L->top - 1); + lua_unlock(L); + return ttnov(L->top - 1); +} + + +LUA_API int lua_getfield (lua_State *L, int idx, const char *k) { + lua_lock(L); + return auxgetstr(L, index2addr(L, idx), k); +} + + +LUA_API int lua_geti (lua_State *L, int idx, lua_Integer n) { + StkId t; + const TValue *slot; + lua_lock(L); + t = index2addr(L, idx); + if (luaV_fastget(L, t, n, slot, luaH_getint)) { + setobj2s(L, L->top, slot); + api_incr_top(L); + } + else { + setivalue(L->top, n); + api_incr_top(L); + luaV_finishget(L, t, L->top - 1, L->top - 1, slot); + } + lua_unlock(L); + return ttnov(L->top - 1); +} + + +LUA_API int lua_rawget (lua_State *L, int idx) { + StkId t; + lua_lock(L); + t = index2addr(L, idx); + api_check(L, ttistable(t), "table expected"); + setobj2s(L, L->top - 1, luaH_get(hvalue(t), L->top - 1)); + lua_unlock(L); + return ttnov(L->top - 1); +} + + +LUA_API int lua_rawgeti (lua_State *L, int idx, lua_Integer n) { + StkId t; + lua_lock(L); + t = index2addr(L, idx); + api_check(L, ttistable(t), "table expected"); + setobj2s(L, L->top, luaH_getint(hvalue(t), n)); + api_incr_top(L); + lua_unlock(L); + return ttnov(L->top - 1); +} + + +LUA_API int lua_rawgetp (lua_State *L, int idx, const void *p) { + StkId t; + TValue k; + lua_lock(L); + t = index2addr(L, idx); + api_check(L, ttistable(t), "table expected"); + setpvalue(&k, cast(void *, p)); + setobj2s(L, L->top, luaH_get(hvalue(t), &k)); + api_incr_top(L); + lua_unlock(L); + return ttnov(L->top - 1); +} + + +LUA_API void lua_createtable (lua_State *L, int narray, int nrec) { + Table *t; + lua_lock(L); + t = luaH_new(L); + sethvalue(L, L->top, t); + api_incr_top(L); + if (narray > 0 || nrec > 0) + luaH_resize(L, t, narray, nrec); + luaC_checkGC(L); + lua_unlock(L); +} + + +LUA_API int lua_getmetatable (lua_State *L, int objindex) { + const TValue *obj; + Table *mt; + int res = 0; + lua_lock(L); + obj = index2addr(L, objindex); + switch (ttnov(obj)) { + case LUA_TTABLE: + mt = hvalue(obj)->metatable; + break; + case LUA_TUSERDATA: + mt = uvalue(obj)->metatable; + break; + default: + mt = G(L)->mt[ttnov(obj)]; + break; + } + if (mt != NULL) { + sethvalue(L, L->top, mt); + api_incr_top(L); + res = 1; + } + lua_unlock(L); + return res; +} + + +LUA_API int lua_getuservalue (lua_State *L, int idx) { + StkId o; + lua_lock(L); + o = index2addr(L, idx); + api_check(L, ttisfulluserdata(o), "full userdata expected"); + getuservalue(L, uvalue(o), L->top); + api_incr_top(L); + lua_unlock(L); + return ttnov(L->top - 1); +} + + +/* +** set functions (stack -> Lua) +*/ + +/* +** t[k] = value at the top of the stack (where 'k' is a string) +*/ +static void auxsetstr (lua_State *L, const TValue *t, const char *k) { + const TValue *slot; + TString *str = luaS_new(L, k); + api_checknelems(L, 1); + if (luaV_fastset(L, t, str, slot, luaH_getstr, L->top - 1)) + L->top--; /* pop value */ + else { + setsvalue2s(L, L->top, str); /* push 'str' (to make it a TValue) */ + api_incr_top(L); + luaV_finishset(L, t, L->top - 1, L->top - 2, slot); + L->top -= 2; /* pop value and key */ + } + lua_unlock(L); /* lock done by caller */ +} + + +LUA_API void lua_setglobal (lua_State *L, const char *name) { + Table *reg = hvalue(&G(L)->l_registry); + lua_lock(L); /* unlock done in 'auxsetstr' */ + auxsetstr(L, luaH_getint(reg, LUA_RIDX_GLOBALS), name); +} + + +LUA_API void lua_settable (lua_State *L, int idx) { + StkId t; + lua_lock(L); + api_checknelems(L, 2); + t = index2addr(L, idx); + luaV_settable(L, t, L->top - 2, L->top - 1); + L->top -= 2; /* pop index and value */ + lua_unlock(L); +} + + +LUA_API void lua_setfield (lua_State *L, int idx, const char *k) { + lua_lock(L); /* unlock done in 'auxsetstr' */ + auxsetstr(L, index2addr(L, idx), k); +} + + +LUA_API void lua_seti (lua_State *L, int idx, lua_Integer n) { + StkId t; + const TValue *slot; + lua_lock(L); + api_checknelems(L, 1); + t = index2addr(L, idx); + if (luaV_fastset(L, t, n, slot, luaH_getint, L->top - 1)) + L->top--; /* pop value */ + else { + setivalue(L->top, n); + api_incr_top(L); + luaV_finishset(L, t, L->top - 1, L->top - 2, slot); + L->top -= 2; /* pop value and key */ + } + lua_unlock(L); +} + + +LUA_API void lua_rawset (lua_State *L, int idx) { + StkId o; + TValue *slot; + lua_lock(L); + api_checknelems(L, 2); + o = index2addr(L, idx); + api_check(L, ttistable(o), "table expected"); + slot = luaH_set(L, hvalue(o), L->top - 2); + setobj2t(L, slot, L->top - 1); + invalidateTMcache(hvalue(o)); + luaC_barrierback(L, hvalue(o), L->top-1); + L->top -= 2; + lua_unlock(L); +} + + +LUA_API void lua_rawseti (lua_State *L, int idx, lua_Integer n) { + StkId o; + lua_lock(L); + api_checknelems(L, 1); + o = index2addr(L, idx); + api_check(L, ttistable(o), "table expected"); + luaH_setint(L, hvalue(o), n, L->top - 1); + luaC_barrierback(L, hvalue(o), L->top-1); + L->top--; + lua_unlock(L); +} + + +LUA_API void lua_rawsetp (lua_State *L, int idx, const void *p) { + StkId o; + TValue k, *slot; + lua_lock(L); + api_checknelems(L, 1); + o = index2addr(L, idx); + api_check(L, ttistable(o), "table expected"); + setpvalue(&k, cast(void *, p)); + slot = luaH_set(L, hvalue(o), &k); + setobj2t(L, slot, L->top - 1); + luaC_barrierback(L, hvalue(o), L->top - 1); + L->top--; + lua_unlock(L); +} + + +LUA_API int lua_setmetatable (lua_State *L, int objindex) { + TValue *obj; + Table *mt; + lua_lock(L); + api_checknelems(L, 1); + obj = index2addr(L, objindex); + if (ttisnil(L->top - 1)) + mt = NULL; + else { + api_check(L, ttistable(L->top - 1), "table expected"); + mt = hvalue(L->top - 1); + } + switch (ttnov(obj)) { + case LUA_TTABLE: { + hvalue(obj)->metatable = mt; + if (mt) { + luaC_objbarrier(L, gcvalue(obj), mt); + luaC_checkfinalizer(L, gcvalue(obj), mt); + } + break; + } + case LUA_TUSERDATA: { + uvalue(obj)->metatable = mt; + if (mt) { + luaC_objbarrier(L, uvalue(obj), mt); + luaC_checkfinalizer(L, gcvalue(obj), mt); + } + break; + } + default: { + G(L)->mt[ttnov(obj)] = mt; + break; + } + } + L->top--; + lua_unlock(L); + return 1; +} + + +LUA_API void lua_setuservalue (lua_State *L, int idx) { + StkId o; + lua_lock(L); + api_checknelems(L, 1); + o = index2addr(L, idx); + api_check(L, ttisfulluserdata(o), "full userdata expected"); + setuservalue(L, uvalue(o), L->top - 1); + luaC_barrier(L, gcvalue(o), L->top - 1); + L->top--; + lua_unlock(L); +} + + +/* +** 'load' and 'call' functions (run Lua code) +*/ + + +#define checkresults(L,na,nr) \ + api_check(L, (nr) == LUA_MULTRET || (L->ci->top - L->top >= (nr) - (na)), \ + "results from function overflow current stack size") + + +LUA_API void lua_callk (lua_State *L, int nargs, int nresults, + lua_KContext ctx, lua_KFunction k) { + StkId func; + lua_lock(L); + api_check(L, k == NULL || !isLua(L->ci), + "cannot use continuations inside hooks"); + api_checknelems(L, nargs+1); + api_check(L, L->status == LUA_OK, "cannot do calls on non-normal thread"); + checkresults(L, nargs, nresults); + func = L->top - (nargs+1); + if (k != NULL && L->nny == 0) { /* need to prepare continuation? */ + L->ci->u.c.k = k; /* save continuation */ + L->ci->u.c.ctx = ctx; /* save context */ + luaD_call(L, func, nresults); /* do the call */ + } + else /* no continuation or no yieldable */ + luaD_callnoyield(L, func, nresults); /* just do the call */ + adjustresults(L, nresults); + lua_unlock(L); +} + + + +/* +** Execute a protected call. +*/ +struct CallS { /* data to 'f_call' */ + StkId func; + int nresults; +}; + + +static void f_call (lua_State *L, void *ud) { + struct CallS *c = cast(struct CallS *, ud); + luaD_callnoyield(L, c->func, c->nresults); +} + + + +LUA_API int lua_pcallk (lua_State *L, int nargs, int nresults, int errfunc, + lua_KContext ctx, lua_KFunction k) { + struct CallS c; + int status; + ptrdiff_t func; + lua_lock(L); + api_check(L, k == NULL || !isLua(L->ci), + "cannot use continuations inside hooks"); + api_checknelems(L, nargs+1); + api_check(L, L->status == LUA_OK, "cannot do calls on non-normal thread"); + checkresults(L, nargs, nresults); + if (errfunc == 0) + func = 0; + else { + StkId o = index2addr(L, errfunc); + api_checkstackindex(L, errfunc, o); + func = savestack(L, o); + } + c.func = L->top - (nargs+1); /* function to be called */ + if (k == NULL || L->nny > 0) { /* no continuation or no yieldable? */ + c.nresults = nresults; /* do a 'conventional' protected call */ + status = luaD_pcall(L, f_call, &c, savestack(L, c.func), func); + } + else { /* prepare continuation (call is already protected by 'resume') */ + CallInfo *ci = L->ci; + ci->u.c.k = k; /* save continuation */ + ci->u.c.ctx = ctx; /* save context */ + /* save information for error recovery */ + ci->extra = savestack(L, c.func); + ci->u.c.old_errfunc = L->errfunc; + L->errfunc = func; + setoah(ci->callstatus, L->allowhook); /* save value of 'allowhook' */ + ci->callstatus |= CIST_YPCALL; /* function can do error recovery */ + luaD_call(L, c.func, nresults); /* do the call */ + ci->callstatus &= ~CIST_YPCALL; + L->errfunc = ci->u.c.old_errfunc; + status = LUA_OK; /* if it is here, there were no errors */ + } + adjustresults(L, nresults); + lua_unlock(L); + return status; +} + + +LUA_API int lua_load (lua_State *L, lua_Reader reader, void *data, + const char *chunkname, const char *mode) { + ZIO z; + int status; + lua_lock(L); + if (!chunkname) chunkname = "?"; + luaZ_init(L, &z, reader, data); + status = luaD_protectedparser(L, &z, chunkname, mode); + if (status == LUA_OK) { /* no errors? */ + LClosure *f = clLvalue(L->top - 1); /* get newly created function */ + if (f->nupvalues >= 1) { /* does it have an upvalue? */ + /* get global table from registry */ + Table *reg = hvalue(&G(L)->l_registry); + const TValue *gt = luaH_getint(reg, LUA_RIDX_GLOBALS); + /* set global table as 1st upvalue of 'f' (may be LUA_ENV) */ + setobj(L, f->upvals[0]->v, gt); + luaC_upvalbarrier(L, f->upvals[0]); + } + } + lua_unlock(L); + return status; +} + + +LUA_API int lua_dump (lua_State *L, lua_Writer writer, void *data, int strip) { + int status; + TValue *o; + lua_lock(L); + api_checknelems(L, 1); + o = L->top - 1; + if (isLfunction(o)) + status = luaU_dump(L, getproto(o), writer, data, strip); + else + status = 1; + lua_unlock(L); + return status; +} + + +LUA_API int lua_status (lua_State *L) { + return L->status; +} + + +/* +** Garbage-collection function +*/ + +LUA_API int lua_gc (lua_State *L, int what, int data) { + int res = 0; + global_State *g; + lua_lock(L); + g = G(L); + switch (what) { + case LUA_GCSTOP: { + g->gcrunning = 0; + break; + } + case LUA_GCRESTART: { + luaE_setdebt(g, 0); + g->gcrunning = 1; + break; + } + case LUA_GCCOLLECT: { + luaC_fullgc(L, 0); + break; + } + case LUA_GCCOUNT: { + /* GC values are expressed in Kbytes: #bytes/2^10 */ + res = cast_int(gettotalbytes(g) >> 10); + break; + } + case LUA_GCCOUNTB: { + res = cast_int(gettotalbytes(g) & 0x3ff); + break; + } + case LUA_GCSTEP: { + l_mem debt = 1; /* =1 to signal that it did an actual step */ + lu_byte oldrunning = g->gcrunning; + g->gcrunning = 1; /* allow GC to run */ + if (data == 0) { + luaE_setdebt(g, -GCSTEPSIZE); /* to do a "small" step */ + luaC_step(L); + } + else { /* add 'data' to total debt */ + debt = cast(l_mem, data) * 1024 + g->GCdebt; + luaE_setdebt(g, debt); + luaC_checkGC(L); + } + g->gcrunning = oldrunning; /* restore previous state */ + if (debt > 0 && g->gcstate == GCSpause) /* end of cycle? */ + res = 1; /* signal it */ + break; + } + case LUA_GCSETPAUSE: { + res = g->gcpause; + g->gcpause = data; + break; + } + case LUA_GCSETSTEPMUL: { + res = g->gcstepmul; + if (data < 40) data = 40; /* avoid ridiculous low values (and 0) */ + g->gcstepmul = data; + break; + } + case LUA_GCISRUNNING: { + res = g->gcrunning; + break; + } + default: res = -1; /* invalid option */ + } + lua_unlock(L); + return res; +} + + + +/* +** miscellaneous functions +*/ + + +LUA_API int lua_error (lua_State *L) { + lua_lock(L); + api_checknelems(L, 1); + luaG_errormsg(L); + /* code unreachable; will unlock when control actually leaves the kernel */ + return 0; /* to avoid warnings */ +} + + +LUA_API int lua_next (lua_State *L, int idx) { + StkId t; + int more; + lua_lock(L); + t = index2addr(L, idx); + api_check(L, ttistable(t), "table expected"); + more = luaH_next(L, hvalue(t), L->top - 1); + if (more) { + api_incr_top(L); + } + else /* no more elements */ + L->top -= 1; /* remove key */ + lua_unlock(L); + return more; +} + + +LUA_API void lua_concat (lua_State *L, int n) { + lua_lock(L); + api_checknelems(L, n); + if (n >= 2) { + luaV_concat(L, n); + } + else if (n == 0) { /* push empty string */ + setsvalue2s(L, L->top, luaS_newlstr(L, "", 0)); + api_incr_top(L); + } + /* else n == 1; nothing to do */ + luaC_checkGC(L); + lua_unlock(L); +} + + +LUA_API void lua_len (lua_State *L, int idx) { + StkId t; + lua_lock(L); + t = index2addr(L, idx); + luaV_objlen(L, L->top, t); + api_incr_top(L); + lua_unlock(L); +} + + +LUA_API lua_Alloc lua_getallocf (lua_State *L, void **ud) { + lua_Alloc f; + lua_lock(L); + if (ud) *ud = G(L)->ud; + f = G(L)->frealloc; + lua_unlock(L); + return f; +} + + +LUA_API void lua_setallocf (lua_State *L, lua_Alloc f, void *ud) { + lua_lock(L); + G(L)->ud = ud; + G(L)->frealloc = f; + lua_unlock(L); +} + + +LUA_API void *lua_newuserdata (lua_State *L, size_t size) { + Udata *u; + lua_lock(L); + u = luaS_newudata(L, size); + setuvalue(L, L->top, u); + api_incr_top(L); + luaC_checkGC(L); + lua_unlock(L); + return getudatamem(u); +} + + + +static const char *aux_upvalue (StkId fi, int n, TValue **val, + CClosure **owner, UpVal **uv) { + switch (ttype(fi)) { + case LUA_TCCL: { /* C closure */ + CClosure *f = clCvalue(fi); + if (!(1 <= n && n <= f->nupvalues)) return NULL; + *val = &f->upvalue[n-1]; + if (owner) *owner = f; + return ""; + } + case LUA_TLCL: { /* Lua closure */ + LClosure *f = clLvalue(fi); + TString *name; + Proto *p = f->p; + if (!(1 <= n && n <= p->sizeupvalues)) return NULL; + *val = f->upvals[n-1]->v; + if (uv) *uv = f->upvals[n - 1]; + name = p->upvalues[n-1].name; + return (name == NULL) ? "(*no name)" : getstr(name); + } + default: return NULL; /* not a closure */ + } +} + + +LUA_API const char *lua_getupvalue (lua_State *L, int funcindex, int n) { + const char *name; + TValue *val = NULL; /* to avoid warnings */ + lua_lock(L); + name = aux_upvalue(index2addr(L, funcindex), n, &val, NULL, NULL); + if (name) { + setobj2s(L, L->top, val); + api_incr_top(L); + } + lua_unlock(L); + return name; +} + + +LUA_API const char *lua_setupvalue (lua_State *L, int funcindex, int n) { + const char *name; + TValue *val = NULL; /* to avoid warnings */ + CClosure *owner = NULL; + UpVal *uv = NULL; + StkId fi; + lua_lock(L); + fi = index2addr(L, funcindex); + api_checknelems(L, 1); + name = aux_upvalue(fi, n, &val, &owner, &uv); + if (name) { + L->top--; + setobj(L, val, L->top); + if (owner) { luaC_barrier(L, owner, L->top); } + else if (uv) { luaC_upvalbarrier(L, uv); } + } + lua_unlock(L); + return name; +} + + +static UpVal **getupvalref (lua_State *L, int fidx, int n) { + LClosure *f; + StkId fi = index2addr(L, fidx); + api_check(L, ttisLclosure(fi), "Lua function expected"); + f = clLvalue(fi); + api_check(L, (1 <= n && n <= f->p->sizeupvalues), "invalid upvalue index"); + return &f->upvals[n - 1]; /* get its upvalue pointer */ +} + + +LUA_API void *lua_upvalueid (lua_State *L, int fidx, int n) { + StkId fi = index2addr(L, fidx); + switch (ttype(fi)) { + case LUA_TLCL: { /* lua closure */ + return *getupvalref(L, fidx, n); + } + case LUA_TCCL: { /* C closure */ + CClosure *f = clCvalue(fi); + api_check(L, 1 <= n && n <= f->nupvalues, "invalid upvalue index"); + return &f->upvalue[n - 1]; + } + default: { + api_check(L, 0, "closure expected"); + return NULL; + } + } +} + + +LUA_API void lua_upvaluejoin (lua_State *L, int fidx1, int n1, + int fidx2, int n2) { + UpVal **up1 = getupvalref(L, fidx1, n1); + UpVal **up2 = getupvalref(L, fidx2, n2); + if (*up1 == *up2) + return; + luaC_upvdeccount(L, *up1); + *up1 = *up2; + (*up1)->refcount++; + if (upisopen(*up1)) (*up1)->u.open.touched = 1; + luaC_upvalbarrier(L, *up1); +} + + diff --git a/src/lapi.h b/src/lapi.h new file mode 100644 index 0000000..8e16ad5 --- /dev/null +++ b/src/lapi.h @@ -0,0 +1,24 @@ +/* +** $Id: lapi.h,v 2.9.1.1 2017/04/19 17:20:42 roberto Exp $ +** Auxiliary functions from Lua API +** See Copyright Notice in lua.h +*/ + +#ifndef lapi_h +#define lapi_h + + +#include "llimits.h" +#include "lstate.h" + +#define api_incr_top(L) {L->top++; api_check(L, L->top <= L->ci->top, \ + "stack overflow");} + +#define adjustresults(L,nres) \ + { if ((nres) == LUA_MULTRET && L->ci->top < L->top) L->ci->top = L->top; } + +#define api_checknelems(L,n) api_check(L, (n) < (L->top - L->ci->func), \ + "not enough elements in the stack") + + +#endif diff --git a/src/lauxlib.c b/src/lauxlib.c new file mode 100644 index 0000000..ac68bd3 --- /dev/null +++ b/src/lauxlib.c @@ -0,0 +1,1048 @@ +/* +** $Id: lauxlib.c,v 1.289.1.1 2017/04/19 17:20:42 roberto Exp $ +** Auxiliary functions for building Lua libraries +** See Copyright Notice in lua.h +*/ + +#define lauxlib_c +#define LUA_LIB + +#include "lprefix.h" + + +#include <errno.h> +#include <stdarg.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> + + +/* +** This file uses only the official API of Lua. +** Any function declared here could be written as an application function. +*/ + +#include "lua.h" + +#include "lauxlib.h" + + +/* +** {====================================================== +** Traceback +** ======================================================= +*/ + + +#define LEVELS1 10 /* size of the first part of the stack */ +#define LEVELS2 11 /* size of the second part of the stack */ + + + +/* +** search for 'objidx' in table at index -1. +** return 1 + string at top if find a good name. +*/ +static int findfield (lua_State *L, int objidx, int level) { + if (level == 0 || !lua_istable(L, -1)) + return 0; /* not found */ + lua_pushnil(L); /* start 'next' loop */ + while (lua_next(L, -2)) { /* for each pair in table */ + if (lua_type(L, -2) == LUA_TSTRING) { /* ignore non-string keys */ + if (lua_rawequal(L, objidx, -1)) { /* found object? */ + lua_pop(L, 1); /* remove value (but keep name) */ + return 1; + } + else if (findfield(L, objidx, level - 1)) { /* try recursively */ + lua_remove(L, -2); /* remove table (but keep name) */ + lua_pushliteral(L, "."); + lua_insert(L, -2); /* place '.' between the two names */ + lua_concat(L, 3); + return 1; + } + } + lua_pop(L, 1); /* remove value */ + } + return 0; /* not found */ +} + + +/* +** Search for a name for a function in all loaded modules +*/ +static int pushglobalfuncname (lua_State *L, lua_Debug *ar) { + int top = lua_gettop(L); + lua_getinfo(L, "f", ar); /* push function */ + lua_getfield(L, LUA_REGISTRYINDEX, LUA_LOADED_TABLE); + if (findfield(L, top + 1, 2)) { + const char *name = lua_tostring(L, -1); + if (strncmp(name, "_G.", 3) == 0) { /* name start with '_G.'? */ + lua_pushstring(L, name + 3); /* push name without prefix */ + lua_remove(L, -2); /* remove original name */ + } + lua_copy(L, -1, top + 1); /* move name to proper place */ + lua_pop(L, 2); /* remove pushed values */ + return 1; + } + else { + lua_settop(L, top); /* remove function and global table */ + return 0; + } +} + + +static void pushfuncname (lua_State *L, lua_Debug *ar) { + if (pushglobalfuncname(L, ar)) { /* try first a global name */ + lua_pushfstring(L, "function '%s'", lua_tostring(L, -1)); + lua_remove(L, -2); /* remove name */ + } + else if (*ar->namewhat != '\0') /* is there a name from code? */ + lua_pushfstring(L, "%s '%s'", ar->namewhat, ar->name); /* use it */ + else if (*ar->what == 'm') /* main? */ + lua_pushliteral(L, "main chunk"); + else if (*ar->what != 'C') /* for Lua functions, use <file:line> */ + lua_pushfstring(L, "function <%s:%d>", ar->short_src, ar->linedefined); + else /* nothing left... */ + lua_pushliteral(L, "?"); +} + + +static int lastlevel (lua_State *L) { + lua_Debug ar; + int li = 1, le = 1; + /* find an upper bound */ + while (lua_getstack(L, le, &ar)) { li = le; le *= 2; } + /* do a binary search */ + while (li < le) { + int m = (li + le)/2; + if (lua_getstack(L, m, &ar)) li = m + 1; + else le = m; + } + return le - 1; +} + + +LUALIB_API void luaL_traceback (lua_State *L, lua_State *L1, + const char *msg, int level) { + lua_Debug ar; + int top = lua_gettop(L); + int last = lastlevel(L1); + int n1 = (last - level > LEVELS1 + LEVELS2) ? LEVELS1 : -1; + if (msg) + lua_pushfstring(L, "%s\n", msg); + luaL_checkstack(L, 10, NULL); + lua_pushliteral(L, "stack traceback:"); + while (lua_getstack(L1, level++, &ar)) { + if (n1-- == 0) { /* too many levels? */ + lua_pushliteral(L, "\n\t..."); /* add a '...' */ + level = last - LEVELS2 + 1; /* and skip to last ones */ + } + else { + lua_getinfo(L1, "Slnt", &ar); + lua_pushfstring(L, "\n\t%s:", ar.short_src); + if (ar.currentline > 0) + lua_pushfstring(L, "%d:", ar.currentline); + lua_pushliteral(L, " in "); + pushfuncname(L, &ar); + if (ar.istailcall) + lua_pushliteral(L, "\n\t(...tail calls...)"); + lua_concat(L, lua_gettop(L) - top); + } + } + lua_concat(L, lua_gettop(L) - top); +} + +/* }====================================================== */ + + +/* +** {====================================================== +** Error-report functions +** ======================================================= +*/ + +LUALIB_API int luaL_argerror (lua_State *L, int arg, const char *extramsg) { + lua_Debug ar; + if (!lua_getstack(L, 0, &ar)) /* no stack frame? */ + return luaL_error(L, "bad argument #%d (%s)", arg, extramsg); + lua_getinfo(L, "n", &ar); + if (strcmp(ar.namewhat, "method") == 0) { + arg--; /* do not count 'self' */ + if (arg == 0) /* error is in the self argument itself? */ + return luaL_error(L, "calling '%s' on bad self (%s)", + ar.name, extramsg); + } + if (ar.name == NULL) + ar.name = (pushglobalfuncname(L, &ar)) ? lua_tostring(L, -1) : "?"; + return luaL_error(L, "bad argument #%d to '%s' (%s)", + arg, ar.name, extramsg); +} + + +static int typeerror (lua_State *L, int arg, const char *tname) { + const char *msg; + const char *typearg; /* name for the type of the actual argument */ + if (luaL_getmetafield(L, arg, "__name") == LUA_TSTRING) + typearg = lua_tostring(L, -1); /* use the given type name */ + else if (lua_type(L, arg) == LUA_TLIGHTUSERDATA) + typearg = "light userdata"; /* special name for messages */ + else + typearg = luaL_typename(L, arg); /* standard name */ + msg = lua_pushfstring(L, "%s expected, got %s", tname, typearg); + return luaL_argerror(L, arg, msg); +} + + +static void tag_error (lua_State *L, int arg, int tag) { + typeerror(L, arg, lua_typename(L, tag)); +} + + +/* +** The use of 'lua_pushfstring' ensures this function does not +** need reserved stack space when called. +*/ +LUALIB_API void luaL_where (lua_State *L, int level) { + lua_Debug ar; + if (lua_getstack(L, level, &ar)) { /* check function at level */ + lua_getinfo(L, "Sl", &ar); /* get info about it */ + if (ar.currentline > 0) { /* is there info? */ + lua_pushfstring(L, "%s:%d: ", ar.short_src, ar.currentline); + return; + } + } + lua_pushfstring(L, ""); /* else, no information available... */ +} + + +/* +** Again, the use of 'lua_pushvfstring' ensures this function does +** not need reserved stack space when called. (At worst, it generates +** an error with "stack overflow" instead of the given message.) +*/ +LUALIB_API int luaL_error (lua_State *L, const char *fmt, ...) { + va_list argp; + va_start(argp, fmt); + luaL_where(L, 1); + lua_pushvfstring(L, fmt, argp); + va_end(argp); + lua_concat(L, 2); + return lua_error(L); +} + + +LUALIB_API int luaL_fileresult (lua_State *L, int stat, const char *fname) { + int en = errno; /* calls to Lua API may change this value */ + if (stat) { + lua_pushboolean(L, 1); + return 1; + } + else { + lua_pushnil(L); + if (fname) + lua_pushfstring(L, "%s: %s", fname, strerror(en)); + else + lua_pushstring(L, strerror(en)); + lua_pushinteger(L, en); + return 3; + } +} + + +#if !defined(l_inspectstat) /* { */ + +#if defined(LUA_USE_POSIX) + +#include <sys/wait.h> + +/* +** use appropriate macros to interpret 'pclose' return status +*/ +#define l_inspectstat(stat,what) \ + if (WIFEXITED(stat)) { stat = WEXITSTATUS(stat); } \ + else if (WIFSIGNALED(stat)) { stat = WTERMSIG(stat); what = "signal"; } + +#else + +#define l_inspectstat(stat,what) /* no op */ + +#endif + +#endif /* } */ + + +LUALIB_API int luaL_execresult (lua_State *L, int stat) { + const char *what = "exit"; /* type of termination */ + if (stat == -1) /* error? */ + return luaL_fileresult(L, 0, NULL); + else { + l_inspectstat(stat, what); /* interpret result */ + if (*what == 'e' && stat == 0) /* successful termination? */ + lua_pushboolean(L, 1); + else + lua_pushnil(L); + lua_pushstring(L, what); + lua_pushinteger(L, stat); + return 3; /* return true/nil,what,code */ + } +} + +/* }====================================================== */ + + +/* +** {====================================================== +** Userdata's metatable manipulation +** ======================================================= +*/ + +LUALIB_API int luaL_newmetatable (lua_State *L, const char *tname) { + if (luaL_getmetatable(L, tname) != LUA_TNIL) /* name already in use? */ + return 0; /* leave previous value on top, but return 0 */ + lua_pop(L, 1); + lua_createtable(L, 0, 2); /* create metatable */ + lua_pushstring(L, tname); + lua_setfield(L, -2, "__name"); /* metatable.__name = tname */ + lua_pushvalue(L, -1); + lua_setfield(L, LUA_REGISTRYINDEX, tname); /* registry.name = metatable */ + return 1; +} + + +LUALIB_API void luaL_setmetatable (lua_State *L, const char *tname) { + luaL_getmetatable(L, tname); + lua_setmetatable(L, -2); +} + + +LUALIB_API void *luaL_testudata (lua_State *L, int ud, const char *tname) { + void *p = lua_touserdata(L, ud); + if (p != NULL) { /* value is a userdata? */ + if (lua_getmetatable(L, ud)) { /* does it have a metatable? */ + luaL_getmetatable(L, tname); /* get correct metatable */ + if (!lua_rawequal(L, -1, -2)) /* not the same? */ + p = NULL; /* value is a userdata with wrong metatable */ + lua_pop(L, 2); /* remove both metatables */ + return p; + } + } + return NULL; /* value is not a userdata with a metatable */ +} + + +LUALIB_API void *luaL_checkudata (lua_State *L, int ud, const char *tname) { + void *p = luaL_testudata(L, ud, tname); + if (p == NULL) typeerror(L, ud, tname); + return p; +} + +/* }====================================================== */ + + +/* +** {====================================================== +** Argument check functions +** ======================================================= +*/ + +LUALIB_API int luaL_checkoption (lua_State *L, int arg, const char *def, + const char *const lst[]) { + const char *name = (def) ? luaL_optstring(L, arg, def) : + luaL_checkstring(L, arg); + int i; + for (i=0; lst[i]; i++) + if (strcmp(lst[i], name) == 0) + return i; + return luaL_argerror(L, arg, + lua_pushfstring(L, "invalid option '%s'", name)); +} + + +/* +** Ensures the stack has at least 'space' extra slots, raising an error +** if it cannot fulfill the request. (The error handling needs a few +** extra slots to format the error message. In case of an error without +** this extra space, Lua will generate the same 'stack overflow' error, +** but without 'msg'.) +*/ +LUALIB_API void luaL_checkstack (lua_State *L, int space, const char *msg) { + if (!lua_checkstack(L, space)) { + if (msg) + luaL_error(L, "stack overflow (%s)", msg); + else + luaL_error(L, "stack overflow"); + } +} + + +LUALIB_API void luaL_checktype (lua_State *L, int arg, int t) { + if (lua_type(L, arg) != t) + tag_error(L, arg, t); +} + + +LUALIB_API void luaL_checkany (lua_State *L, int arg) { + if (lua_type(L, arg) == LUA_TNONE) + luaL_argerror(L, arg, "value expected"); +} + + +LUALIB_API const char *luaL_checklstring (lua_State *L, int arg, size_t *len) { + const char *s = lua_tolstring(L, arg, len); + if (!s) tag_error(L, arg, LUA_TSTRING); + return s; +} + + +LUALIB_API const char *luaL_optlstring (lua_State *L, int arg, + const char *def, size_t *len) { + if (lua_isnoneornil(L, arg)) { + if (len) + *len = (def ? strlen(def) : 0); + return def; + } + else return luaL_checklstring(L, arg, len); +} + + +LUALIB_API lua_Number luaL_checknumber (lua_State *L, int arg) { + int isnum; + lua_Number d = lua_tonumberx(L, arg, &isnum); + if (!isnum) + tag_error(L, arg, LUA_TNUMBER); + return d; +} + + +LUALIB_API lua_Number luaL_optnumber (lua_State *L, int arg, lua_Number def) { + return luaL_opt(L, luaL_checknumber, arg, def); +} + + +static void interror (lua_State *L, int arg) { + if (lua_isnumber(L, arg)) + luaL_argerror(L, arg, "number has no integer representation"); + else + tag_error(L, arg, LUA_TNUMBER); +} + + +LUALIB_API lua_Integer luaL_checkinteger (lua_State *L, int arg) { + int isnum; + lua_Integer d = lua_tointegerx(L, arg, &isnum); + if (!isnum) { + interror(L, arg); + } + return d; +} + + +LUALIB_API lua_Integer luaL_optinteger (lua_State *L, int arg, + lua_Integer def) { + return luaL_opt(L, luaL_checkinteger, arg, def); +} + +/* }====================================================== */ + + +/* +** {====================================================== +** Generic Buffer manipulation +** ======================================================= +*/ + +/* userdata to box arbitrary data */ +typedef struct UBox { + void *box; + size_t bsize; +} UBox; + + +static void *resizebox (lua_State *L, int idx, size_t newsize) { + void *ud; + lua_Alloc allocf = lua_getallocf(L, &ud); + UBox *box = (UBox *)lua_touserdata(L, idx); + void *temp = allocf(ud, box->box, box->bsize, newsize); + if (temp == NULL && newsize > 0) { /* allocation error? */ + resizebox(L, idx, 0); /* free buffer */ + luaL_error(L, "not enough memory for buffer allocation"); + } + box->box = temp; + box->bsize = newsize; + return temp; +} + + +static int boxgc (lua_State *L) { + resizebox(L, 1, 0); + return 0; +} + + +static void *newbox (lua_State *L, size_t newsize) { + UBox *box = (UBox *)lua_newuserdata(L, sizeof(UBox)); + box->box = NULL; + box->bsize = 0; + if (luaL_newmetatable(L, "LUABOX")) { /* creating metatable? */ + lua_pushcfunction(L, boxgc); + lua_setfield(L, -2, "__gc"); /* metatable.__gc = boxgc */ + } + lua_setmetatable(L, -2); + return resizebox(L, -1, newsize); +} + + +/* +** check whether buffer is using a userdata on the stack as a temporary +** buffer +*/ +#define buffonstack(B) ((B)->b != (B)->initb) + + +/* +** returns a pointer to a free area with at least 'sz' bytes +*/ +LUALIB_API char *luaL_prepbuffsize (luaL_Buffer *B, size_t sz) { + lua_State *L = B->L; + if (B->size - B->n < sz) { /* not enough space? */ + char *newbuff; + size_t newsize = B->size * 2; /* double buffer size */ + if (newsize - B->n < sz) /* not big enough? */ + newsize = B->n + sz; + if (newsize < B->n || newsize - B->n < sz) + luaL_error(L, "buffer too large"); + /* create larger buffer */ + if (buffonstack(B)) + newbuff = (char *)resizebox(L, -1, newsize); + else { /* no buffer yet */ + newbuff = (char *)newbox(L, newsize); + memcpy(newbuff, B->b, B->n * sizeof(char)); /* copy original content */ + } + B->b = newbuff; + B->size = newsize; + } + return &B->b[B->n]; +} + + +LUALIB_API void luaL_addlstring (luaL_Buffer *B, const char *s, size_t l) { + if (l > 0) { /* avoid 'memcpy' when 's' can be NULL */ + char *b = luaL_prepbuffsize(B, l); + memcpy(b, s, l * sizeof(char)); + luaL_addsize(B, l); + } +} + + +LUALIB_API void luaL_addstring (luaL_Buffer *B, const char *s) { + luaL_addlstring(B, s, strlen(s)); +} + + +LUALIB_API void luaL_pushresult (luaL_Buffer *B) { + lua_State *L = B->L; + lua_pushlstring(L, B->b, B->n); + if (buffonstack(B)) { + resizebox(L, -2, 0); /* delete old buffer */ + lua_remove(L, -2); /* remove its header from the stack */ + } +} + + +LUALIB_API void luaL_pushresultsize (luaL_Buffer *B, size_t sz) { + luaL_addsize(B, sz); + luaL_pushresult(B); +} + + +LUALIB_API void luaL_addvalue (luaL_Buffer *B) { + lua_State *L = B->L; + size_t l; + const char *s = lua_tolstring(L, -1, &l); + if (buffonstack(B)) + lua_insert(L, -2); /* put value below buffer */ + luaL_addlstring(B, s, l); + lua_remove(L, (buffonstack(B)) ? -2 : -1); /* remove value */ +} + + +LUALIB_API void luaL_buffinit (lua_State *L, luaL_Buffer *B) { + B->L = L; + B->b = B->initb; + B->n = 0; + B->size = LUAL_BUFFERSIZE; +} + + +LUALIB_API char *luaL_buffinitsize (lua_State *L, luaL_Buffer *B, size_t sz) { + luaL_buffinit(L, B); + return luaL_prepbuffsize(B, sz); +} + +/* }====================================================== */ + + +/* +** {====================================================== +** Reference system +** ======================================================= +*/ + +/* index of free-list header */ +#define freelist 0 + + +LUALIB_API int luaL_ref (lua_State *L, int t) { + int ref; + if (lua_isnil(L, -1)) { + lua_pop(L, 1); /* remove from stack */ + return LUA_REFNIL; /* 'nil' has a unique fixed reference */ + } + t = lua_absindex(L, t); + lua_rawgeti(L, t, freelist); /* get first free element */ + ref = (int)lua_tointeger(L, -1); /* ref = t[freelist] */ + lua_pop(L, 1); /* remove it from stack */ + if (ref != 0) { /* any free element? */ + lua_rawgeti(L, t, ref); /* remove it from list */ + lua_rawseti(L, t, freelist); /* (t[freelist] = t[ref]) */ + } + else /* no free elements */ + ref = (int)lua_rawlen(L, t) + 1; /* get a new reference */ + lua_rawseti(L, t, ref); + return ref; +} + + +LUALIB_API void luaL_unref (lua_State *L, int t, int ref) { + if (ref >= 0) { + t = lua_absindex(L, t); + lua_rawgeti(L, t, freelist); + lua_rawseti(L, t, ref); /* t[ref] = t[freelist] */ + lua_pushinteger(L, ref); + lua_rawseti(L, t, freelist); /* t[freelist] = ref */ + } +} + +/* }====================================================== */ + + +/* +** {====================================================== +** Load functions +** ======================================================= +*/ + +typedef struct LoadF { + int n; /* number of pre-read characters */ + FILE *f; /* file being read */ + char buff[BUFSIZ]; /* area for reading file */ +} LoadF; + + +static const char *getF (lua_State *L, void *ud, size_t *size) { + LoadF *lf = (LoadF *)ud; + (void)L; /* not used */ + if (lf->n > 0) { /* are there pre-read characters to be read? */ + *size = lf->n; /* return them (chars already in buffer) */ + lf->n = 0; /* no more pre-read characters */ + } + else { /* read a block from file */ + /* 'fread' can return > 0 *and* set the EOF flag. If next call to + 'getF' called 'fread', it might still wait for user input. + The next check avoids this problem. */ + if (feof(lf->f)) return NULL; + *size = fread(lf->buff, 1, sizeof(lf->buff), lf->f); /* read block */ + } + return lf->buff; +} + + +static int errfile (lua_State *L, const char *what, int fnameindex) { + const char *serr = strerror(errno); + const char *filename = lua_tostring(L, fnameindex) + 1; + lua_pushfstring(L, "cannot %s %s: %s", what, filename, serr); + lua_remove(L, fnameindex); + return LUA_ERRFILE; +} + + +static int skipBOM (LoadF *lf) { + const char *p = "\xEF\xBB\xBF"; /* UTF-8 BOM mark */ + int c; + lf->n = 0; + do { + c = getc(lf->f); + if (c == EOF || c != *(const unsigned char *)p++) return c; + lf->buff[lf->n++] = c; /* to be read by the parser */ + } while (*p != '\0'); + lf->n = 0; /* prefix matched; discard it */ + return getc(lf->f); /* return next character */ +} + + +/* +** reads the first character of file 'f' and skips an optional BOM mark +** in its beginning plus its first line if it starts with '#'. Returns +** true if it skipped the first line. In any case, '*cp' has the +** first "valid" character of the file (after the optional BOM and +** a first-line comment). +*/ +static int skipcomment (LoadF *lf, int *cp) { + int c = *cp = skipBOM(lf); + if (c == '#') { /* first line is a comment (Unix exec. file)? */ + do { /* skip first line */ + c = getc(lf->f); + } while (c != EOF && c != '\n'); + *cp = getc(lf->f); /* skip end-of-line, if present */ + return 1; /* there was a comment */ + } + else return 0; /* no comment */ +} + + +LUALIB_API int luaL_loadfilex (lua_State *L, const char *filename, + const char *mode) { + LoadF lf; + int status, readstatus; + int c; + int fnameindex = lua_gettop(L) + 1; /* index of filename on the stack */ + if (filename == NULL) { + lua_pushliteral(L, "=stdin"); + lf.f = stdin; + } + else { + lua_pushfstring(L, "@%s", filename); + lf.f = fopen(filename, "r"); + if (lf.f == NULL) return errfile(L, "open", fnameindex); + } + if (skipcomment(&lf, &c)) /* read initial portion */ + lf.buff[lf.n++] = '\n'; /* add line to correct line numbers */ + if (c == LUA_SIGNATURE[0] && filename) { /* binary file? */ + lf.f = freopen(filename, "rb", lf.f); /* reopen in binary mode */ + if (lf.f == NULL) return errfile(L, "reopen", fnameindex); + skipcomment(&lf, &c); /* re-read initial portion */ + } + if (c != EOF) + lf.buff[lf.n++] = c; /* 'c' is the first character of the stream */ + status = lua_load(L, getF, &lf, lua_tostring(L, -1), mode); + readstatus = ferror(lf.f); + if (filename) fclose(lf.f); /* close file (even in case of errors) */ + if (readstatus) { + lua_settop(L, fnameindex); /* ignore results from 'lua_load' */ + return errfile(L, "read", fnameindex); + } + lua_remove(L, fnameindex); + return status; +} + + +typedef struct LoadS { + const char *s; + size_t size; +} LoadS; + + +static const char *getS (lua_State *L, void *ud, size_t *size) { + LoadS *ls = (LoadS *)ud; + (void)L; /* not used */ + if (ls->size == 0) return NULL; + *size = ls->size; + ls->size = 0; + return ls->s; +} + + +LUALIB_API int luaL_loadbufferx (lua_State *L, const char *buff, size_t size, + const char *name, const char *mode) { + LoadS ls; + ls.s = buff; + ls.size = size; + return lua_load(L, getS, &ls, name, mode); +} + + +LUALIB_API int luaL_loadstring (lua_State *L, const char *s) { + return luaL_loadbuffer(L, s, strlen(s), s); +} + +/* }====================================================== */ + + + +LUALIB_API int luaL_getmetafield (lua_State *L, int obj, const char *event) { + if (!lua_getmetatable(L, obj)) /* no metatable? */ + return LUA_TNIL; + else { + int tt; + lua_pushstring(L, event); + tt = lua_rawget(L, -2); + if (tt == LUA_TNIL) /* is metafield nil? */ + lua_pop(L, 2); /* remove metatable and metafield */ + else + lua_remove(L, -2); /* remove only metatable */ + return tt; /* return metafield type */ + } +} + + +LUALIB_API int luaL_callmeta (lua_State *L, int obj, const char *event) { + obj = lua_absindex(L, obj); + if (luaL_getmetafield(L, obj, event) == LUA_TNIL) /* no metafield? */ + return 0; + lua_pushvalue(L, obj); + lua_call(L, 1, 1); + return 1; +} + + +LUALIB_API lua_Integer luaL_len (lua_State *L, int idx) { + lua_Integer l; + int isnum; + lua_len(L, idx); + l = lua_tointegerx(L, -1, &isnum); + if (!isnum) + luaL_error(L, "object length is not an integer"); + lua_pop(L, 1); /* remove object */ + return l; +} + + +LUALIB_API const char *luaL_tolstring (lua_State *L, int idx, size_t *len) { + if (luaL_callmeta(L, idx, "__tostring")) { /* metafield? */ + if (!lua_isstring(L, -1)) + luaL_error(L, "'__tostring' must return a string"); + } + else { + switch (lua_type(L, idx)) { + case LUA_TNUMBER: { + if (lua_isinteger(L, idx)) + lua_pushfstring(L, "%I", (LUAI_UACINT)lua_tointeger(L, idx)); + else + lua_pushfstring(L, "%f", (LUAI_UACNUMBER)lua_tonumber(L, idx)); + break; + } + case LUA_TSTRING: + lua_pushvalue(L, idx); + break; + case LUA_TBOOLEAN: + lua_pushstring(L, (lua_toboolean(L, idx) ? "true" : "false")); + break; + case LUA_TNIL: + lua_pushliteral(L, "nil"); + break; + default: { + int tt = luaL_getmetafield(L, idx, "__name"); /* try name */ + const char *kind = (tt == LUA_TSTRING) ? lua_tostring(L, -1) : + luaL_typename(L, idx); + lua_pushfstring(L, "%s: %p", kind, lua_topointer(L, idx)); + if (tt != LUA_TNIL) + lua_remove(L, -2); /* remove '__name' */ + break; + } + } + } + return lua_tolstring(L, -1, len); +} + + +/* +** {====================================================== +** Compatibility with 5.1 module functions +** ======================================================= +*/ +#if defined(LUA_COMPAT_MODULE) + +static const char *luaL_findtable (lua_State *L, int idx, + const char *fname, int szhint) { + const char *e; + if (idx) lua_pushvalue(L, idx); + do { + e = strchr(fname, '.'); + if (e == NULL) e = fname + strlen(fname); + lua_pushlstring(L, fname, e - fname); + if (lua_rawget(L, -2) == LUA_TNIL) { /* no such field? */ + lua_pop(L, 1); /* remove this nil */ + lua_createtable(L, 0, (*e == '.' ? 1 : szhint)); /* new table for field */ + lua_pushlstring(L, fname, e - fname); + lua_pushvalue(L, -2); + lua_settable(L, -4); /* set new table into field */ + } + else if (!lua_istable(L, -1)) { /* field has a non-table value? */ + lua_pop(L, 2); /* remove table and value */ + return fname; /* return problematic part of the name */ + } + lua_remove(L, -2); /* remove previous table */ + fname = e + 1; + } while (*e == '.'); + return NULL; +} + + +/* +** Count number of elements in a luaL_Reg list. +*/ +static int libsize (const luaL_Reg *l) { + int size = 0; + for (; l && l->name; l++) size++; + return size; +} + + +/* +** Find or create a module table with a given name. The function +** first looks at the LOADED table and, if that fails, try a +** global variable with that name. In any case, leaves on the stack +** the module table. +*/ +LUALIB_API void luaL_pushmodule (lua_State *L, const char *modname, + int sizehint) { + luaL_findtable(L, LUA_REGISTRYINDEX, LUA_LOADED_TABLE, 1); + if (lua_getfield(L, -1, modname) != LUA_TTABLE) { /* no LOADED[modname]? */ + lua_pop(L, 1); /* remove previous result */ + /* try global variable (and create one if it does not exist) */ + lua_pushglobaltable(L); + if (luaL_findtable(L, 0, modname, sizehint) != NULL) + luaL_error(L, "name conflict for module '%s'", modname); + lua_pushvalue(L, -1); + lua_setfield(L, -3, modname); /* LOADED[modname] = new table */ + } + lua_remove(L, -2); /* remove LOADED table */ +} + + +LUALIB_API void luaL_openlib (lua_State *L, const char *libname, + const luaL_Reg *l, int nup) { + luaL_checkversion(L); + if (libname) { + luaL_pushmodule(L, libname, libsize(l)); /* get/create library table */ + lua_insert(L, -(nup + 1)); /* move library table to below upvalues */ + } + if (l) + luaL_setfuncs(L, l, nup); + else + lua_pop(L, nup); /* remove upvalues */ +} + +#endif +/* }====================================================== */ + +/* +** set functions from list 'l' into table at top - 'nup'; each +** function gets the 'nup' elements at the top as upvalues. +** Returns with only the table at the stack. +*/ +LUALIB_API void luaL_setfuncs (lua_State *L, const luaL_Reg *l, int nup) { + luaL_checkstack(L, nup, "too many upvalues"); + for (; l->name != NULL; l++) { /* fill the table with given functions */ + int i; + for (i = 0; i < nup; i++) /* copy upvalues to the top */ + lua_pushvalue(L, -nup); + lua_pushcclosure(L, l->func, nup); /* closure with those upvalues */ + lua_setfield(L, -(nup + 2), l->name); + } + lua_pop(L, nup); /* remove upvalues */ +} + + +/* +** ensure that stack[idx][fname] has a table and push that table +** into the stack +*/ +LUALIB_API int luaL_getsubtable (lua_State *L, int idx, const char *fname) { + if (lua_getfield(L, idx, fname) == LUA_TTABLE) + return 1; /* table already there */ + else { + lua_pop(L, 1); /* remove previous result */ + idx = lua_absindex(L, idx); + lua_newtable(L); + lua_pushvalue(L, -1); /* copy to be left at top */ + lua_setfield(L, idx, fname); /* assign new table to field */ + return 0; /* false, because did not find table there */ + } +} + + +/* +** Stripped-down 'require': After checking "loaded" table, calls 'openf' +** to open a module, registers the result in 'package.loaded' table and, +** if 'glb' is true, also registers the result in the global table. +** Leaves resulting module on the top. +*/ +LUALIB_API void luaL_requiref (lua_State *L, const char *modname, + lua_CFunction openf, int glb) { + luaL_getsubtable(L, LUA_REGISTRYINDEX, LUA_LOADED_TABLE); + lua_getfield(L, -1, modname); /* LOADED[modname] */ + if (!lua_toboolean(L, -1)) { /* package not already loaded? */ + lua_pop(L, 1); /* remove field */ + lua_pushcfunction(L, openf); + lua_pushstring(L, modname); /* argument to open function */ + lua_call(L, 1, 1); /* call 'openf' to open module */ + lua_pushvalue(L, -1); /* make copy of module (call result) */ + lua_setfield(L, -3, modname); /* LOADED[modname] = module */ + } + lua_remove(L, -2); /* remove LOADED table */ + if (glb) { + lua_pushvalue(L, -1); /* copy of module */ + lua_setglobal(L, modname); /* _G[modname] = module */ + } +} + + +LUALIB_API const char *luaL_gsub (lua_State *L, const char *s, const char *p, + const char *r) { + const char *wild; + size_t l = strlen(p); + luaL_Buffer b; + luaL_buffinit(L, &b); + while ((wild = strstr(s, p)) != NULL) { + luaL_addlstring(&b, s, wild - s); /* push prefix */ + luaL_addstring(&b, r); /* push replacement in place of pattern */ + s = wild + l; /* continue after 'p' */ + } + luaL_addstring(&b, s); /* push last suffix */ + luaL_pushresult(&b); + return lua_tostring(L, -1); +} + + +static void *l_alloc (void *ud, void *ptr, size_t osize, size_t nsize) { + (void)ud; (void)osize; /* not used */ + if (nsize == 0) { + free(ptr); + return NULL; + } + else { /* cannot fail when shrinking a block */ + void *newptr = realloc(ptr, nsize); + if (newptr == NULL && ptr != NULL && nsize <= osize) + return ptr; /* keep the original block */ + else /* no fail or not shrinking */ + return newptr; /* use the new block */ + } +} + + +static int panic (lua_State *L) { + lua_writestringerror("PANIC: unprotected error in call to Lua API (%s)\n", + lua_tostring(L, -1)); + return 0; /* return to Lua to abort */ +} + + +LUALIB_API lua_State *luaL_newstate (void) { + lua_State *L = lua_newstate(l_alloc, NULL); + if (L) lua_atpanic(L, &panic); + return L; +} + + +LUALIB_API void luaL_checkversion_ (lua_State *L, lua_Number ver, size_t sz) { + const lua_Number *v = lua_version(L); + if (sz != LUAL_NUMSIZES) /* check numeric types */ + luaL_error(L, "core and library have incompatible numeric types"); + if (v != lua_version(NULL)) + luaL_error(L, "multiple Lua VMs detected"); + else if (*v != ver) + luaL_error(L, "version mismatch: app. needs %f, Lua core provides %f", + (LUAI_UACNUMBER)ver, (LUAI_UACNUMBER)*v); +} + diff --git a/src/lauxlib.h b/src/lauxlib.h new file mode 100644 index 0000000..9857d3a --- /dev/null +++ b/src/lauxlib.h @@ -0,0 +1,264 @@ +/* +** $Id: lauxlib.h,v 1.131.1.1 2017/04/19 17:20:42 roberto Exp $ +** Auxiliary functions for building Lua libraries +** See Copyright Notice in lua.h +*/ + + +#ifndef lauxlib_h +#define lauxlib_h + + +#include <stddef.h> +#include <stdio.h> + +#include "lua.h" + + + +/* extra error code for 'luaL_loadfilex' */ +#define LUA_ERRFILE (LUA_ERRERR+1) + + +/* key, in the registry, for table of loaded modules */ +#define LUA_LOADED_TABLE "_LOADED" + + +/* key, in the registry, for table of preloaded loaders */ +#define LUA_PRELOAD_TABLE "_PRELOAD" + + +typedef struct luaL_Reg { + const char *name; + lua_CFunction func; +} luaL_Reg; + + +#define LUAL_NUMSIZES (sizeof(lua_Integer)*16 + sizeof(lua_Number)) + +LUALIB_API void (luaL_checkversion_) (lua_State *L, lua_Number ver, size_t sz); +#define luaL_checkversion(L) \ + luaL_checkversion_(L, LUA_VERSION_NUM, LUAL_NUMSIZES) + +LUALIB_API int (luaL_getmetafield) (lua_State *L, int obj, const char *e); +LUALIB_API int (luaL_callmeta) (lua_State *L, int obj, const char *e); +LUALIB_API const char *(luaL_tolstring) (lua_State *L, int idx, size_t *len); +LUALIB_API int (luaL_argerror) (lua_State *L, int arg, const char *extramsg); +LUALIB_API const char *(luaL_checklstring) (lua_State *L, int arg, + size_t *l); +LUALIB_API const char *(luaL_optlstring) (lua_State *L, int arg, + const char *def, size_t *l); +LUALIB_API lua_Number (luaL_checknumber) (lua_State *L, int arg); +LUALIB_API lua_Number (luaL_optnumber) (lua_State *L, int arg, lua_Number def); + +LUALIB_API lua_Integer (luaL_checkinteger) (lua_State *L, int arg); +LUALIB_API lua_Integer (luaL_optinteger) (lua_State *L, int arg, + lua_Integer def); + +LUALIB_API void (luaL_checkstack) (lua_State *L, int sz, const char *msg); +LUALIB_API void (luaL_checktype) (lua_State *L, int arg, int t); +LUALIB_API void (luaL_checkany) (lua_State *L, int arg); + +LUALIB_API int (luaL_newmetatable) (lua_State *L, const char *tname); +LUALIB_API void (luaL_setmetatable) (lua_State *L, const char *tname); +LUALIB_API void *(luaL_testudata) (lua_State *L, int ud, const char *tname); +LUALIB_API void *(luaL_checkudata) (lua_State *L, int ud, const char *tname); + +LUALIB_API void (luaL_where) (lua_State *L, int lvl); +LUALIB_API int (luaL_error) (lua_State *L, const char *fmt, ...); + +LUALIB_API int (luaL_checkoption) (lua_State *L, int arg, const char *def, + const char *const lst[]); + +LUALIB_API int (luaL_fileresult) (lua_State *L, int stat, const char *fname); +LUALIB_API int (luaL_execresult) (lua_State *L, int stat); + +/* predefined references */ +#define LUA_NOREF (-2) +#define LUA_REFNIL (-1) + +LUALIB_API int (luaL_ref) (lua_State *L, int t); +LUALIB_API void (luaL_unref) (lua_State *L, int t, int ref); + +LUALIB_API int (luaL_loadfilex) (lua_State *L, const char *filename, + const char *mode); + +#define luaL_loadfile(L,f) luaL_loadfilex(L,f,NULL) + +LUALIB_API int (luaL_loadbufferx) (lua_State *L, const char *buff, size_t sz, + const char *name, const char *mode); +LUALIB_API int (luaL_loadstring) (lua_State *L, const char *s); + +LUALIB_API lua_State *(luaL_newstate) (void); + +LUALIB_API lua_Integer (luaL_len) (lua_State *L, int idx); + +LUALIB_API const char *(luaL_gsub) (lua_State *L, const char *s, const char *p, + const char *r); + +LUALIB_API void (luaL_setfuncs) (lua_State *L, const luaL_Reg *l, int nup); + +LUALIB_API int (luaL_getsubtable) (lua_State *L, int idx, const char *fname); + +LUALIB_API void (luaL_traceback) (lua_State *L, lua_State *L1, + const char *msg, int level); + +LUALIB_API void (luaL_requiref) (lua_State *L, const char *modname, + lua_CFunction openf, int glb); + +/* +** =============================================================== +** some useful macros +** =============================================================== +*/ + + +#define luaL_newlibtable(L,l) \ + lua_createtable(L, 0, sizeof(l)/sizeof((l)[0]) - 1) + +#define luaL_newlib(L,l) \ + (luaL_checkversion(L), luaL_newlibtable(L,l), luaL_setfuncs(L,l,0)) + +#define luaL_argcheck(L, cond,arg,extramsg) \ + ((void)((cond) || luaL_argerror(L, (arg), (extramsg)))) +#define luaL_checkstring(L,n) (luaL_checklstring(L, (n), NULL)) +#define luaL_optstring(L,n,d) (luaL_optlstring(L, (n), (d), NULL)) + +#define luaL_typename(L,i) lua_typename(L, lua_type(L,(i))) + +#define luaL_dofile(L, fn) \ + (luaL_loadfile(L, fn) || lua_pcall(L, 0, LUA_MULTRET, 0)) + +#define luaL_dostring(L, s) \ + (luaL_loadstring(L, s) || lua_pcall(L, 0, LUA_MULTRET, 0)) + +#define luaL_getmetatable(L,n) (lua_getfield(L, LUA_REGISTRYINDEX, (n))) + +#define luaL_opt(L,f,n,d) (lua_isnoneornil(L,(n)) ? (d) : f(L,(n))) + +#define luaL_loadbuffer(L,s,sz,n) luaL_loadbufferx(L,s,sz,n,NULL) + + +/* +** {====================================================== +** Generic Buffer manipulation +** ======================================================= +*/ + +typedef struct luaL_Buffer { + char *b; /* buffer address */ + size_t size; /* buffer size */ + size_t n; /* number of characters in buffer */ + lua_State *L; + char initb[LUAL_BUFFERSIZE]; /* initial buffer */ +} luaL_Buffer; + + +#define luaL_addchar(B,c) \ + ((void)((B)->n < (B)->size || luaL_prepbuffsize((B), 1)), \ + ((B)->b[(B)->n++] = (c))) + +#define luaL_addsize(B,s) ((B)->n += (s)) + +LUALIB_API void (luaL_buffinit) (lua_State *L, luaL_Buffer *B); +LUALIB_API char *(luaL_prepbuffsize) (luaL_Buffer *B, size_t sz); +LUALIB_API void (luaL_addlstring) (luaL_Buffer *B, const char *s, size_t l); +LUALIB_API void (luaL_addstring) (luaL_Buffer *B, const char *s); +LUALIB_API void (luaL_addvalue) (luaL_Buffer *B); +LUALIB_API void (luaL_pushresult) (luaL_Buffer *B); +LUALIB_API void (luaL_pushresultsize) (luaL_Buffer *B, size_t sz); +LUALIB_API char *(luaL_buffinitsize) (lua_State *L, luaL_Buffer *B, size_t sz); + +#define luaL_prepbuffer(B) luaL_prepbuffsize(B, LUAL_BUFFERSIZE) + +/* }====================================================== */ + + + +/* +** {====================================================== +** File handles for IO library +** ======================================================= +*/ + +/* +** A file handle is a userdata with metatable 'LUA_FILEHANDLE' and +** initial structure 'luaL_Stream' (it may contain other fields +** after that initial structure). +*/ + +#define LUA_FILEHANDLE "FILE*" + + +typedef struct luaL_Stream { + FILE *f; /* stream (NULL for incompletely created streams) */ + lua_CFunction closef; /* to close stream (NULL for closed streams) */ +} luaL_Stream; + +/* }====================================================== */ + + + +/* compatibility with old module system */ +#if defined(LUA_COMPAT_MODULE) + +LUALIB_API void (luaL_pushmodule) (lua_State *L, const char *modname, + int sizehint); +LUALIB_API void (luaL_openlib) (lua_State *L, const char *libname, + const luaL_Reg *l, int nup); + +#define luaL_register(L,n,l) (luaL_openlib(L,(n),(l),0)) + +#endif + + +/* +** {================================================================== +** "Abstraction Layer" for basic report of messages and errors +** =================================================================== +*/ + +/* print a string */ +#if !defined(lua_writestring) +#define lua_writestring(s,l) fwrite((s), sizeof(char), (l), stdout) +#endif + +/* print a newline and flush the output */ +#if !defined(lua_writeline) +#define lua_writeline() (lua_writestring("\n", 1), fflush(stdout)) +#endif + +/* print an error message */ +#if !defined(lua_writestringerror) +#define lua_writestringerror(s,p) \ + (fprintf(stderr, (s), (p)), fflush(stderr)) +#endif + +/* }================================================================== */ + + +/* +** {============================================================ +** Compatibility with deprecated conversions +** ============================================================= +*/ +#if defined(LUA_COMPAT_APIINTCASTS) + +#define luaL_checkunsigned(L,a) ((lua_Unsigned)luaL_checkinteger(L,a)) +#define luaL_optunsigned(L,a,d) \ + ((lua_Unsigned)luaL_optinteger(L,a,(lua_Integer)(d))) + +#define luaL_checkint(L,n) ((int)luaL_checkinteger(L, (n))) +#define luaL_optint(L,n,d) ((int)luaL_optinteger(L, (n), (d))) + +#define luaL_checklong(L,n) ((long)luaL_checkinteger(L, (n))) +#define luaL_optlong(L,n,d) ((long)luaL_optinteger(L, (n), (d))) + +#endif +/* }============================================================ */ + + + +#endif + + diff --git a/src/lbaselib.c b/src/lbaselib.c new file mode 100644 index 0000000..6460e4f --- /dev/null +++ b/src/lbaselib.c @@ -0,0 +1,498 @@ +/* +** $Id: lbaselib.c,v 1.314.1.1 2017/04/19 17:39:34 roberto Exp $ +** Basic library +** See Copyright Notice in lua.h +*/ + +#define lbaselib_c +#define LUA_LIB + +#include "lprefix.h" + + +#include <ctype.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> + +#include "lua.h" + +#include "lauxlib.h" +#include "lualib.h" + + +static int luaB_print (lua_State *L) { + int n = lua_gettop(L); /* number of arguments */ + int i; + lua_getglobal(L, "tostring"); + for (i=1; i<=n; i++) { + const char *s; + size_t l; + lua_pushvalue(L, -1); /* function to be called */ + lua_pushvalue(L, i); /* value to print */ + lua_call(L, 1, 1); + s = lua_tolstring(L, -1, &l); /* get result */ + if (s == NULL) + return luaL_error(L, "'tostring' must return a string to 'print'"); + if (i>1) lua_writestring("\t", 1); + lua_writestring(s, l); + lua_pop(L, 1); /* pop result */ + } + lua_writeline(); + return 0; +} + + +#define SPACECHARS " \f\n\r\t\v" + +static const char *b_str2int (const char *s, int base, lua_Integer *pn) { + lua_Unsigned n = 0; + int neg = 0; + s += strspn(s, SPACECHARS); /* skip initial spaces */ + if (*s == '-') { s++; neg = 1; } /* handle signal */ + else if (*s == '+') s++; + if (!isalnum((unsigned char)*s)) /* no digit? */ + return NULL; + do { + int digit = (isdigit((unsigned char)*s)) ? *s - '0' + : (toupper((unsigned char)*s) - 'A') + 10; + if (digit >= base) return NULL; /* invalid numeral */ + n = n * base + digit; + s++; + } while (isalnum((unsigned char)*s)); + s += strspn(s, SPACECHARS); /* skip trailing spaces */ + *pn = (lua_Integer)((neg) ? (0u - n) : n); + return s; +} + + +static int luaB_tonumber (lua_State *L) { + if (lua_isnoneornil(L, 2)) { /* standard conversion? */ + luaL_checkany(L, 1); + if (lua_type(L, 1) == LUA_TNUMBER) { /* already a number? */ + lua_settop(L, 1); /* yes; return it */ + return 1; + } + else { + size_t l; + const char *s = lua_tolstring(L, 1, &l); + if (s != NULL && lua_stringtonumber(L, s) == l + 1) + return 1; /* successful conversion to number */ + /* else not a number */ + } + } + else { + size_t l; + const char *s; + lua_Integer n = 0; /* to avoid warnings */ + lua_Integer base = luaL_checkinteger(L, 2); + luaL_checktype(L, 1, LUA_TSTRING); /* no numbers as strings */ + s = lua_tolstring(L, 1, &l); + luaL_argcheck(L, 2 <= base && base <= 36, 2, "base out of range"); + if (b_str2int(s, (int)base, &n) == s + l) { + lua_pushinteger(L, n); + return 1; + } /* else not a number */ + } /* else not a number */ + lua_pushnil(L); /* not a number */ + return 1; +} + + +static int luaB_error (lua_State *L) { + int level = (int)luaL_optinteger(L, 2, 1); + lua_settop(L, 1); + if (lua_type(L, 1) == LUA_TSTRING && level > 0) { + luaL_where(L, level); /* add extra information */ + lua_pushvalue(L, 1); + lua_concat(L, 2); + } + return lua_error(L); +} + + +static int luaB_getmetatable (lua_State *L) { + luaL_checkany(L, 1); + if (!lua_getmetatable(L, 1)) { + lua_pushnil(L); + return 1; /* no metatable */ + } + luaL_getmetafield(L, 1, "__metatable"); + return 1; /* returns either __metatable field (if present) or metatable */ +} + + +static int luaB_setmetatable (lua_State *L) { + int t = lua_type(L, 2); + luaL_checktype(L, 1, LUA_TTABLE); + luaL_argcheck(L, t == LUA_TNIL || t == LUA_TTABLE, 2, + "nil or table expected"); + if (luaL_getmetafield(L, 1, "__metatable") != LUA_TNIL) + return luaL_error(L, "cannot change a protected metatable"); + lua_settop(L, 2); + lua_setmetatable(L, 1); + return 1; +} + + +static int luaB_rawequal (lua_State *L) { + luaL_checkany(L, 1); + luaL_checkany(L, 2); + lua_pushboolean(L, lua_rawequal(L, 1, 2)); + return 1; +} + + +static int luaB_rawlen (lua_State *L) { + int t = lua_type(L, 1); + luaL_argcheck(L, t == LUA_TTABLE || t == LUA_TSTRING, 1, + "table or string expected"); + lua_pushinteger(L, lua_rawlen(L, 1)); + return 1; +} + + +static int luaB_rawget (lua_State *L) { + luaL_checktype(L, 1, LUA_TTABLE); + luaL_checkany(L, 2); + lua_settop(L, 2); + lua_rawget(L, 1); + return 1; +} + +static int luaB_rawset (lua_State *L) { + luaL_checktype(L, 1, LUA_TTABLE); + luaL_checkany(L, 2); + luaL_checkany(L, 3); + lua_settop(L, 3); + lua_rawset(L, 1); + return 1; +} + + +static int luaB_collectgarbage (lua_State *L) { + static const char *const opts[] = {"stop", "restart", "collect", + "count", "step", "setpause", "setstepmul", + "isrunning", NULL}; + static const int optsnum[] = {LUA_GCSTOP, LUA_GCRESTART, LUA_GCCOLLECT, + LUA_GCCOUNT, LUA_GCSTEP, LUA_GCSETPAUSE, LUA_GCSETSTEPMUL, + LUA_GCISRUNNING}; + int o = optsnum[luaL_checkoption(L, 1, "collect", opts)]; + int ex = (int)luaL_optinteger(L, 2, 0); + int res = lua_gc(L, o, ex); + switch (o) { + case LUA_GCCOUNT: { + int b = lua_gc(L, LUA_GCCOUNTB, 0); + lua_pushnumber(L, (lua_Number)res + ((lua_Number)b/1024)); + return 1; + } + case LUA_GCSTEP: case LUA_GCISRUNNING: { + lua_pushboolean(L, res); + return 1; + } + default: { + lua_pushinteger(L, res); + return 1; + } + } +} + + +static int luaB_type (lua_State *L) { + int t = lua_type(L, 1); + luaL_argcheck(L, t != LUA_TNONE, 1, "value expected"); + lua_pushstring(L, lua_typename(L, t)); + return 1; +} + + +static int pairsmeta (lua_State *L, const char *method, int iszero, + lua_CFunction iter) { + luaL_checkany(L, 1); + if (luaL_getmetafield(L, 1, method) == LUA_TNIL) { /* no metamethod? */ + lua_pushcfunction(L, iter); /* will return generator, */ + lua_pushvalue(L, 1); /* state, */ + if (iszero) lua_pushinteger(L, 0); /* and initial value */ + else lua_pushnil(L); + } + else { + lua_pushvalue(L, 1); /* argument 'self' to metamethod */ + lua_call(L, 1, 3); /* get 3 values from metamethod */ + } + return 3; +} + + +static int luaB_next (lua_State *L) { + luaL_checktype(L, 1, LUA_TTABLE); + lua_settop(L, 2); /* create a 2nd argument if there isn't one */ + if (lua_next(L, 1)) + return 2; + else { + lua_pushnil(L); + return 1; + } +} + + +static int luaB_pairs (lua_State *L) { + return pairsmeta(L, "__pairs", 0, luaB_next); +} + + +/* +** Traversal function for 'ipairs' +*/ +static int ipairsaux (lua_State *L) { + lua_Integer i = luaL_checkinteger(L, 2) + 1; + lua_pushinteger(L, i); + return (lua_geti(L, 1, i) == LUA_TNIL) ? 1 : 2; +} + + +/* +** 'ipairs' function. Returns 'ipairsaux', given "table", 0. +** (The given "table" may not be a table.) +*/ +static int luaB_ipairs (lua_State *L) { +#if defined(LUA_COMPAT_IPAIRS) + return pairsmeta(L, "__ipairs", 1, ipairsaux); +#else + luaL_checkany(L, 1); + lua_pushcfunction(L, ipairsaux); /* iteration function */ + lua_pushvalue(L, 1); /* state */ + lua_pushinteger(L, 0); /* initial value */ + return 3; +#endif +} + + +static int load_aux (lua_State *L, int status, int envidx) { + if (status == LUA_OK) { + if (envidx != 0) { /* 'env' parameter? */ + lua_pushvalue(L, envidx); /* environment for loaded function */ + if (!lua_setupvalue(L, -2, 1)) /* set it as 1st upvalue */ + lua_pop(L, 1); /* remove 'env' if not used by previous call */ + } + return 1; + } + else { /* error (message is on top of the stack) */ + lua_pushnil(L); + lua_insert(L, -2); /* put before error message */ + return 2; /* return nil plus error message */ + } +} + + +static int luaB_loadfile (lua_State *L) { + const char *fname = luaL_optstring(L, 1, NULL); + const char *mode = luaL_optstring(L, 2, NULL); + int env = (!lua_isnone(L, 3) ? 3 : 0); /* 'env' index or 0 if no 'env' */ + int status = luaL_loadfilex(L, fname, mode); + return load_aux(L, status, env); +} + + +/* +** {====================================================== +** Generic Read function +** ======================================================= +*/ + + +/* +** reserved slot, above all arguments, to hold a copy of the returned +** string to avoid it being collected while parsed. 'load' has four +** optional arguments (chunk, source name, mode, and environment). +*/ +#define RESERVEDSLOT 5 + + +/* +** Reader for generic 'load' function: 'lua_load' uses the +** stack for internal stuff, so the reader cannot change the +** stack top. Instead, it keeps its resulting string in a +** reserved slot inside the stack. +*/ +static const char *generic_reader (lua_State *L, void *ud, size_t *size) { + (void)(ud); /* not used */ + luaL_checkstack(L, 2, "too many nested functions"); + lua_pushvalue(L, 1); /* get function */ + lua_call(L, 0, 1); /* call it */ + if (lua_isnil(L, -1)) { + lua_pop(L, 1); /* pop result */ + *size = 0; + return NULL; + } + else if (!lua_isstring(L, -1)) + luaL_error(L, "reader function must return a string"); + lua_replace(L, RESERVEDSLOT); /* save string in reserved slot */ + return lua_tolstring(L, RESERVEDSLOT, size); +} + + +static int luaB_load (lua_State *L) { + int status; + size_t l; + const char *s = lua_tolstring(L, 1, &l); + const char *mode = luaL_optstring(L, 3, "bt"); + int env = (!lua_isnone(L, 4) ? 4 : 0); /* 'env' index or 0 if no 'env' */ + if (s != NULL) { /* loading a string? */ + const char *chunkname = luaL_optstring(L, 2, s); + status = luaL_loadbufferx(L, s, l, chunkname, mode); + } + else { /* loading from a reader function */ + const char *chunkname = luaL_optstring(L, 2, "=(load)"); + luaL_checktype(L, 1, LUA_TFUNCTION); + lua_settop(L, RESERVEDSLOT); /* create reserved slot */ + status = lua_load(L, generic_reader, NULL, chunkname, mode); + } + return load_aux(L, status, env); +} + +/* }====================================================== */ + + +static int dofilecont (lua_State *L, int d1, lua_KContext d2) { + (void)d1; (void)d2; /* only to match 'lua_Kfunction' prototype */ + return lua_gettop(L) - 1; +} + + +static int luaB_dofile (lua_State *L) { + const char *fname = luaL_optstring(L, 1, NULL); + lua_settop(L, 1); + if (luaL_loadfile(L, fname) != LUA_OK) + return lua_error(L); + lua_callk(L, 0, LUA_MULTRET, 0, dofilecont); + return dofilecont(L, 0, 0); +} + + +static int luaB_assert (lua_State *L) { + if (lua_toboolean(L, 1)) /* condition is true? */ + return lua_gettop(L); /* return all arguments */ + else { /* error */ + luaL_checkany(L, 1); /* there must be a condition */ + lua_remove(L, 1); /* remove it */ + lua_pushliteral(L, "assertion failed!"); /* default message */ + lua_settop(L, 1); /* leave only message (default if no other one) */ + return luaB_error(L); /* call 'error' */ + } +} + + +static int luaB_select (lua_State *L) { + int n = lua_gettop(L); + if (lua_type(L, 1) == LUA_TSTRING && *lua_tostring(L, 1) == '#') { + lua_pushinteger(L, n-1); + return 1; + } + else { + lua_Integer i = luaL_checkinteger(L, 1); + if (i < 0) i = n + i; + else if (i > n) i = n; + luaL_argcheck(L, 1 <= i, 1, "index out of range"); + return n - (int)i; + } +} + + +/* +** Continuation function for 'pcall' and 'xpcall'. Both functions +** already pushed a 'true' before doing the call, so in case of success +** 'finishpcall' only has to return everything in the stack minus +** 'extra' values (where 'extra' is exactly the number of items to be +** ignored). +*/ +static int finishpcall (lua_State *L, int status, lua_KContext extra) { + if (status != LUA_OK && status != LUA_YIELD) { /* error? */ + lua_pushboolean(L, 0); /* first result (false) */ + lua_pushvalue(L, -2); /* error message */ + return 2; /* return false, msg */ + } + else + return lua_gettop(L) - (int)extra; /* return all results */ +} + + +static int luaB_pcall (lua_State *L) { + int status; + luaL_checkany(L, 1); + lua_pushboolean(L, 1); /* first result if no errors */ + lua_insert(L, 1); /* put it in place */ + status = lua_pcallk(L, lua_gettop(L) - 2, LUA_MULTRET, 0, 0, finishpcall); + return finishpcall(L, status, 0); +} + + +/* +** Do a protected call with error handling. After 'lua_rotate', the +** stack will have <f, err, true, f, [args...]>; so, the function passes +** 2 to 'finishpcall' to skip the 2 first values when returning results. +*/ +static int luaB_xpcall (lua_State *L) { + int status; + int n = lua_gettop(L); + luaL_checktype(L, 2, LUA_TFUNCTION); /* check error function */ + lua_pushboolean(L, 1); /* first result */ + lua_pushvalue(L, 1); /* function */ + lua_rotate(L, 3, 2); /* move them below function's arguments */ + status = lua_pcallk(L, n - 2, LUA_MULTRET, 2, 2, finishpcall); + return finishpcall(L, status, 2); +} + + +static int luaB_tostring (lua_State *L) { + luaL_checkany(L, 1); + luaL_tolstring(L, 1, NULL); + return 1; +} + + +static const luaL_Reg base_funcs[] = { + {"assert", luaB_assert}, + {"collectgarbage", luaB_collectgarbage}, + {"dofile", luaB_dofile}, + {"error", luaB_error}, + {"getmetatable", luaB_getmetatable}, + {"ipairs", luaB_ipairs}, + {"loadfile", luaB_loadfile}, + {"load", luaB_load}, +#if defined(LUA_COMPAT_LOADSTRING) + {"loadstring", luaB_load}, +#endif + {"next", luaB_next}, + {"pairs", luaB_pairs}, + {"pcall", luaB_pcall}, + {"print", luaB_print}, + {"rawequal", luaB_rawequal}, + {"rawlen", luaB_rawlen}, + {"rawget", luaB_rawget}, + {"rawset", luaB_rawset}, + {"select", luaB_select}, + {"setmetatable", luaB_setmetatable}, + {"tonumber", luaB_tonumber}, + {"tostring", luaB_tostring}, + {"type", luaB_type}, + {"xpcall", luaB_xpcall}, + /* placeholders */ + {"_G", NULL}, + {"_VERSION", NULL}, + {NULL, NULL} +}; + + +LUAMOD_API int luaopen_base (lua_State *L) { + /* open lib into global table */ + lua_pushglobaltable(L); + luaL_setfuncs(L, base_funcs, 0); + /* set global _G */ + lua_pushvalue(L, -1); + lua_setfield(L, -2, "_G"); + /* set global _VERSION */ + lua_pushliteral(L, LUA_VERSION); + lua_setfield(L, -2, "_VERSION"); + return 1; +} + diff --git a/src/lbitlib.c b/src/lbitlib.c new file mode 100644 index 0000000..4786c0d --- /dev/null +++ b/src/lbitlib.c @@ -0,0 +1,233 @@ +/* +** $Id: lbitlib.c,v 1.30.1.1 2017/04/19 17:20:42 roberto Exp $ +** Standard library for bitwise operations +** See Copyright Notice in lua.h +*/ + +#define lbitlib_c +#define LUA_LIB + +#include "lprefix.h" + + +#include "lua.h" + +#include "lauxlib.h" +#include "lualib.h" + + +#if defined(LUA_COMPAT_BITLIB) /* { */ + + +#define pushunsigned(L,n) lua_pushinteger(L, (lua_Integer)(n)) +#define checkunsigned(L,i) ((lua_Unsigned)luaL_checkinteger(L,i)) + + +/* number of bits to consider in a number */ +#if !defined(LUA_NBITS) +#define LUA_NBITS 32 +#endif + + +/* +** a lua_Unsigned with its first LUA_NBITS bits equal to 1. (Shift must +** be made in two parts to avoid problems when LUA_NBITS is equal to the +** number of bits in a lua_Unsigned.) +*/ +#define ALLONES (~(((~(lua_Unsigned)0) << (LUA_NBITS - 1)) << 1)) + + +/* macro to trim extra bits */ +#define trim(x) ((x) & ALLONES) + + +/* builds a number with 'n' ones (1 <= n <= LUA_NBITS) */ +#define mask(n) (~((ALLONES << 1) << ((n) - 1))) + + + +static lua_Unsigned andaux (lua_State *L) { + int i, n = lua_gettop(L); + lua_Unsigned r = ~(lua_Unsigned)0; + for (i = 1; i <= n; i++) + r &= checkunsigned(L, i); + return trim(r); +} + + +static int b_and (lua_State *L) { + lua_Unsigned r = andaux(L); + pushunsigned(L, r); + return 1; +} + + +static int b_test (lua_State *L) { + lua_Unsigned r = andaux(L); + lua_pushboolean(L, r != 0); + return 1; +} + + +static int b_or (lua_State *L) { + int i, n = lua_gettop(L); + lua_Unsigned r = 0; + for (i = 1; i <= n; i++) + r |= checkunsigned(L, i); + pushunsigned(L, trim(r)); + return 1; +} + + +static int b_xor (lua_State *L) { + int i, n = lua_gettop(L); + lua_Unsigned r = 0; + for (i = 1; i <= n; i++) + r ^= checkunsigned(L, i); + pushunsigned(L, trim(r)); + return 1; +} + + +static int b_not (lua_State *L) { + lua_Unsigned r = ~checkunsigned(L, 1); + pushunsigned(L, trim(r)); + return 1; +} + + +static int b_shift (lua_State *L, lua_Unsigned r, lua_Integer i) { + if (i < 0) { /* shift right? */ + i = -i; + r = trim(r); + if (i >= LUA_NBITS) r = 0; + else r >>= i; + } + else { /* shift left */ + if (i >= LUA_NBITS) r = 0; + else r <<= i; + r = trim(r); + } + pushunsigned(L, r); + return 1; +} + + +static int b_lshift (lua_State *L) { + return b_shift(L, checkunsigned(L, 1), luaL_checkinteger(L, 2)); +} + + +static int b_rshift (lua_State *L) { + return b_shift(L, checkunsigned(L, 1), -luaL_checkinteger(L, 2)); +} + + +static int b_arshift (lua_State *L) { + lua_Unsigned r = checkunsigned(L, 1); + lua_Integer i = luaL_checkinteger(L, 2); + if (i < 0 || !(r & ((lua_Unsigned)1 << (LUA_NBITS - 1)))) + return b_shift(L, r, -i); + else { /* arithmetic shift for 'negative' number */ + if (i >= LUA_NBITS) r = ALLONES; + else + r = trim((r >> i) | ~(trim(~(lua_Unsigned)0) >> i)); /* add signal bit */ + pushunsigned(L, r); + return 1; + } +} + + +static int b_rot (lua_State *L, lua_Integer d) { + lua_Unsigned r = checkunsigned(L, 1); + int i = d & (LUA_NBITS - 1); /* i = d % NBITS */ + r = trim(r); + if (i != 0) /* avoid undefined shift of LUA_NBITS when i == 0 */ + r = (r << i) | (r >> (LUA_NBITS - i)); + pushunsigned(L, trim(r)); + return 1; +} + + +static int b_lrot (lua_State *L) { + return b_rot(L, luaL_checkinteger(L, 2)); +} + + +static int b_rrot (lua_State *L) { + return b_rot(L, -luaL_checkinteger(L, 2)); +} + + +/* +** get field and width arguments for field-manipulation functions, +** checking whether they are valid. +** ('luaL_error' called without 'return' to avoid later warnings about +** 'width' being used uninitialized.) +*/ +static int fieldargs (lua_State *L, int farg, int *width) { + lua_Integer f = luaL_checkinteger(L, farg); + lua_Integer w = luaL_optinteger(L, farg + 1, 1); + luaL_argcheck(L, 0 <= f, farg, "field cannot be negative"); + luaL_argcheck(L, 0 < w, farg + 1, "width must be positive"); + if (f + w > LUA_NBITS) + luaL_error(L, "trying to access non-existent bits"); + *width = (int)w; + return (int)f; +} + + +static int b_extract (lua_State *L) { + int w; + lua_Unsigned r = trim(checkunsigned(L, 1)); + int f = fieldargs(L, 2, &w); + r = (r >> f) & mask(w); + pushunsigned(L, r); + return 1; +} + + +static int b_replace (lua_State *L) { + int w; + lua_Unsigned r = trim(checkunsigned(L, 1)); + lua_Unsigned v = trim(checkunsigned(L, 2)); + int f = fieldargs(L, 3, &w); + lua_Unsigned m = mask(w); + r = (r & ~(m << f)) | ((v & m) << f); + pushunsigned(L, r); + return 1; +} + + +static const luaL_Reg bitlib[] = { + {"arshift", b_arshift}, + {"band", b_and}, + {"bnot", b_not}, + {"bor", b_or}, + {"bxor", b_xor}, + {"btest", b_test}, + {"extract", b_extract}, + {"lrotate", b_lrot}, + {"lshift", b_lshift}, + {"replace", b_replace}, + {"rrotate", b_rrot}, + {"rshift", b_rshift}, + {NULL, NULL} +}; + + + +LUAMOD_API int luaopen_bit32 (lua_State *L) { + luaL_newlib(L, bitlib); + return 1; +} + + +#else /* }{ */ + + +LUAMOD_API int luaopen_bit32 (lua_State *L) { + return luaL_error(L, "library 'bit32' has been deprecated"); +} + +#endif /* } */ diff --git a/src/lcode.c b/src/lcode.c new file mode 100644 index 0000000..dc7271d --- /dev/null +++ b/src/lcode.c @@ -0,0 +1,1203 @@ +/* +** $Id: lcode.c,v 2.112.1.1 2017/04/19 17:20:42 roberto Exp $ +** Code generator for Lua +** See Copyright Notice in lua.h +*/ + +#define lcode_c +#define LUA_CORE + +#include "lprefix.h" + + +#include <math.h> +#include <stdlib.h> + +#include "lua.h" + +#include "lcode.h" +#include "ldebug.h" +#include "ldo.h" +#include "lgc.h" +#include "llex.h" +#include "lmem.h" +#include "lobject.h" +#include "lopcodes.h" +#include "lparser.h" +#include "lstring.h" +#include "ltable.h" +#include "lvm.h" + + +/* Maximum number of registers in a Lua function (must fit in 8 bits) */ +#define MAXREGS 255 + + +#define hasjumps(e) ((e)->t != (e)->f) + + +/* +** If expression is a numeric constant, fills 'v' with its value +** and returns 1. Otherwise, returns 0. +*/ +static int tonumeral(const expdesc *e, TValue *v) { + if (hasjumps(e)) + return 0; /* not a numeral */ + switch (e->k) { + case VKINT: + if (v) setivalue(v, e->u.ival); + return 1; + case VKFLT: + if (v) setfltvalue(v, e->u.nval); + return 1; + default: return 0; + } +} + + +/* +** Create a OP_LOADNIL instruction, but try to optimize: if the previous +** instruction is also OP_LOADNIL and ranges are compatible, adjust +** range of previous instruction instead of emitting a new one. (For +** instance, 'local a; local b' will generate a single opcode.) +*/ +void luaK_nil (FuncState *fs, int from, int n) { + Instruction *previous; + int l = from + n - 1; /* last register to set nil */ + if (fs->pc > fs->lasttarget) { /* no jumps to current position? */ + previous = &fs->f->code[fs->pc-1]; + if (GET_OPCODE(*previous) == OP_LOADNIL) { /* previous is LOADNIL? */ + int pfrom = GETARG_A(*previous); /* get previous range */ + int pl = pfrom + GETARG_B(*previous); + if ((pfrom <= from && from <= pl + 1) || + (from <= pfrom && pfrom <= l + 1)) { /* can connect both? */ + if (pfrom < from) from = pfrom; /* from = min(from, pfrom) */ + if (pl > l) l = pl; /* l = max(l, pl) */ + SETARG_A(*previous, from); + SETARG_B(*previous, l - from); + return; + } + } /* else go through */ + } + luaK_codeABC(fs, OP_LOADNIL, from, n - 1, 0); /* else no optimization */ +} + + +/* +** Gets the destination address of a jump instruction. Used to traverse +** a list of jumps. +*/ +static int getjump (FuncState *fs, int pc) { + int offset = GETARG_sBx(fs->f->code[pc]); + if (offset == NO_JUMP) /* point to itself represents end of list */ + return NO_JUMP; /* end of list */ + else + return (pc+1)+offset; /* turn offset into absolute position */ +} + + +/* +** Fix jump instruction at position 'pc' to jump to 'dest'. +** (Jump addresses are relative in Lua) +*/ +static void fixjump (FuncState *fs, int pc, int dest) { + Instruction *jmp = &fs->f->code[pc]; + int offset = dest - (pc + 1); + lua_assert(dest != NO_JUMP); + if (abs(offset) > MAXARG_sBx) + luaX_syntaxerror(fs->ls, "control structure too long"); + SETARG_sBx(*jmp, offset); +} + + +/* +** Concatenate jump-list 'l2' into jump-list 'l1' +*/ +void luaK_concat (FuncState *fs, int *l1, int l2) { + if (l2 == NO_JUMP) return; /* nothing to concatenate? */ + else if (*l1 == NO_JUMP) /* no original list? */ + *l1 = l2; /* 'l1' points to 'l2' */ + else { + int list = *l1; + int next; + while ((next = getjump(fs, list)) != NO_JUMP) /* find last element */ + list = next; + fixjump(fs, list, l2); /* last element links to 'l2' */ + } +} + + +/* +** Create a jump instruction and return its position, so its destination +** can be fixed later (with 'fixjump'). If there are jumps to +** this position (kept in 'jpc'), link them all together so that +** 'patchlistaux' will fix all them directly to the final destination. +*/ +int luaK_jump (FuncState *fs) { + int jpc = fs->jpc; /* save list of jumps to here */ + int j; + fs->jpc = NO_JUMP; /* no more jumps to here */ + j = luaK_codeAsBx(fs, OP_JMP, 0, NO_JUMP); + luaK_concat(fs, &j, jpc); /* keep them on hold */ + return j; +} + + +/* +** Code a 'return' instruction +*/ +void luaK_ret (FuncState *fs, int first, int nret) { + luaK_codeABC(fs, OP_RETURN, first, nret+1, 0); +} + + +/* +** Code a "conditional jump", that is, a test or comparison opcode +** followed by a jump. Return jump position. +*/ +static int condjump (FuncState *fs, OpCode op, int A, int B, int C) { + luaK_codeABC(fs, op, A, B, C); + return luaK_jump(fs); +} + + +/* +** returns current 'pc' and marks it as a jump target (to avoid wrong +** optimizations with consecutive instructions not in the same basic block). +*/ +int luaK_getlabel (FuncState *fs) { + fs->lasttarget = fs->pc; + return fs->pc; +} + + +/* +** Returns the position of the instruction "controlling" a given +** jump (that is, its condition), or the jump itself if it is +** unconditional. +*/ +static Instruction *getjumpcontrol (FuncState *fs, int pc) { + Instruction *pi = &fs->f->code[pc]; + if (pc >= 1 && testTMode(GET_OPCODE(*(pi-1)))) + return pi-1; + else + return pi; +} + + +/* +** Patch destination register for a TESTSET instruction. +** If instruction in position 'node' is not a TESTSET, return 0 ("fails"). +** Otherwise, if 'reg' is not 'NO_REG', set it as the destination +** register. Otherwise, change instruction to a simple 'TEST' (produces +** no register value) +*/ +static int patchtestreg (FuncState *fs, int node, int reg) { + Instruction *i = getjumpcontrol(fs, node); + if (GET_OPCODE(*i) != OP_TESTSET) + return 0; /* cannot patch other instructions */ + if (reg != NO_REG && reg != GETARG_B(*i)) + SETARG_A(*i, reg); + else { + /* no register to put value or register already has the value; + change instruction to simple test */ + *i = CREATE_ABC(OP_TEST, GETARG_B(*i), 0, GETARG_C(*i)); + } + return 1; +} + + +/* +** Traverse a list of tests ensuring no one produces a value +*/ +static void removevalues (FuncState *fs, int list) { + for (; list != NO_JUMP; list = getjump(fs, list)) + patchtestreg(fs, list, NO_REG); +} + + +/* +** Traverse a list of tests, patching their destination address and +** registers: tests producing values jump to 'vtarget' (and put their +** values in 'reg'), other tests jump to 'dtarget'. +*/ +static void patchlistaux (FuncState *fs, int list, int vtarget, int reg, + int dtarget) { + while (list != NO_JUMP) { + int next = getjump(fs, list); + if (patchtestreg(fs, list, reg)) + fixjump(fs, list, vtarget); + else + fixjump(fs, list, dtarget); /* jump to default target */ + list = next; + } +} + + +/* +** Ensure all pending jumps to current position are fixed (jumping +** to current position with no values) and reset list of pending +** jumps +*/ +static void dischargejpc (FuncState *fs) { + patchlistaux(fs, fs->jpc, fs->pc, NO_REG, fs->pc); + fs->jpc = NO_JUMP; +} + + +/* +** Add elements in 'list' to list of pending jumps to "here" +** (current position) +*/ +void luaK_patchtohere (FuncState *fs, int list) { + luaK_getlabel(fs); /* mark "here" as a jump target */ + luaK_concat(fs, &fs->jpc, list); +} + + +/* +** Path all jumps in 'list' to jump to 'target'. +** (The assert means that we cannot fix a jump to a forward address +** because we only know addresses once code is generated.) +*/ +void luaK_patchlist (FuncState *fs, int list, int target) { + if (target == fs->pc) /* 'target' is current position? */ + luaK_patchtohere(fs, list); /* add list to pending jumps */ + else { + lua_assert(target < fs->pc); + patchlistaux(fs, list, target, NO_REG, target); + } +} + + +/* +** Path all jumps in 'list' to close upvalues up to given 'level' +** (The assertion checks that jumps either were closing nothing +** or were closing higher levels, from inner blocks.) +*/ +void luaK_patchclose (FuncState *fs, int list, int level) { + level++; /* argument is +1 to reserve 0 as non-op */ + for (; list != NO_JUMP; list = getjump(fs, list)) { + lua_assert(GET_OPCODE(fs->f->code[list]) == OP_JMP && + (GETARG_A(fs->f->code[list]) == 0 || + GETARG_A(fs->f->code[list]) >= level)); + SETARG_A(fs->f->code[list], level); + } +} + + +/* +** Emit instruction 'i', checking for array sizes and saving also its +** line information. Return 'i' position. +*/ +static int luaK_code (FuncState *fs, Instruction i) { + Proto *f = fs->f; + dischargejpc(fs); /* 'pc' will change */ + /* put new instruction in code array */ + luaM_growvector(fs->ls->L, f->code, fs->pc, f->sizecode, Instruction, + MAX_INT, "opcodes"); + f->code[fs->pc] = i; + /* save corresponding line information */ + luaM_growvector(fs->ls->L, f->lineinfo, fs->pc, f->sizelineinfo, int, + MAX_INT, "opcodes"); + f->lineinfo[fs->pc] = fs->ls->lastline; + return fs->pc++; +} + + +/* +** Format and emit an 'iABC' instruction. (Assertions check consistency +** of parameters versus opcode.) +*/ +int luaK_codeABC (FuncState *fs, OpCode o, int a, int b, int c) { + lua_assert(getOpMode(o) == iABC); + lua_assert(getBMode(o) != OpArgN || b == 0); + lua_assert(getCMode(o) != OpArgN || c == 0); + lua_assert(a <= MAXARG_A && b <= MAXARG_B && c <= MAXARG_C); + return luaK_code(fs, CREATE_ABC(o, a, b, c)); +} + + +/* +** Format and emit an 'iABx' instruction. +*/ +int luaK_codeABx (FuncState *fs, OpCode o, int a, unsigned int bc) { + lua_assert(getOpMode(o) == iABx || getOpMode(o) == iAsBx); + lua_assert(getCMode(o) == OpArgN); + lua_assert(a <= MAXARG_A && bc <= MAXARG_Bx); + return luaK_code(fs, CREATE_ABx(o, a, bc)); +} + + +/* +** Emit an "extra argument" instruction (format 'iAx') +*/ +static int codeextraarg (FuncState *fs, int a) { + lua_assert(a <= MAXARG_Ax); + return luaK_code(fs, CREATE_Ax(OP_EXTRAARG, a)); +} + + +/* +** Emit a "load constant" instruction, using either 'OP_LOADK' +** (if constant index 'k' fits in 18 bits) or an 'OP_LOADKX' +** instruction with "extra argument". +*/ +int luaK_codek (FuncState *fs, int reg, int k) { + if (k <= MAXARG_Bx) + return luaK_codeABx(fs, OP_LOADK, reg, k); + else { + int p = luaK_codeABx(fs, OP_LOADKX, reg, 0); + codeextraarg(fs, k); + return p; + } +} + + +/* +** Check register-stack level, keeping track of its maximum size +** in field 'maxstacksize' +*/ +void luaK_checkstack (FuncState *fs, int n) { + int newstack = fs->freereg + n; + if (newstack > fs->f->maxstacksize) { + if (newstack >= MAXREGS) + luaX_syntaxerror(fs->ls, + "function or expression needs too many registers"); + fs->f->maxstacksize = cast_byte(newstack); + } +} + + +/* +** Reserve 'n' registers in register stack +*/ +void luaK_reserveregs (FuncState *fs, int n) { + luaK_checkstack(fs, n); + fs->freereg += n; +} + + +/* +** Free register 'reg', if it is neither a constant index nor +** a local variable. +) +*/ +static void freereg (FuncState *fs, int reg) { + if (!ISK(reg) && reg >= fs->nactvar) { + fs->freereg--; + lua_assert(reg == fs->freereg); + } +} + + +/* +** Free register used by expression 'e' (if any) +*/ +static void freeexp (FuncState *fs, expdesc *e) { + if (e->k == VNONRELOC) + freereg(fs, e->u.info); +} + + +/* +** Free registers used by expressions 'e1' and 'e2' (if any) in proper +** order. +*/ +static void freeexps (FuncState *fs, expdesc *e1, expdesc *e2) { + int r1 = (e1->k == VNONRELOC) ? e1->u.info : -1; + int r2 = (e2->k == VNONRELOC) ? e2->u.info : -1; + if (r1 > r2) { + freereg(fs, r1); + freereg(fs, r2); + } + else { + freereg(fs, r2); + freereg(fs, r1); + } +} + + +/* +** Add constant 'v' to prototype's list of constants (field 'k'). +** Use scanner's table to cache position of constants in constant list +** and try to reuse constants. Because some values should not be used +** as keys (nil cannot be a key, integer keys can collapse with float +** keys), the caller must provide a useful 'key' for indexing the cache. +*/ +static int addk (FuncState *fs, TValue *key, TValue *v) { + lua_State *L = fs->ls->L; + Proto *f = fs->f; + TValue *idx = luaH_set(L, fs->ls->h, key); /* index scanner table */ + int k, oldsize; + if (ttisinteger(idx)) { /* is there an index there? */ + k = cast_int(ivalue(idx)); + /* correct value? (warning: must distinguish floats from integers!) */ + if (k < fs->nk && ttype(&f->k[k]) == ttype(v) && + luaV_rawequalobj(&f->k[k], v)) + return k; /* reuse index */ + } + /* constant not found; create a new entry */ + oldsize = f->sizek; + k = fs->nk; + /* numerical value does not need GC barrier; + table has no metatable, so it does not need to invalidate cache */ + setivalue(idx, k); + luaM_growvector(L, f->k, k, f->sizek, TValue, MAXARG_Ax, "constants"); + while (oldsize < f->sizek) setnilvalue(&f->k[oldsize++]); + setobj(L, &f->k[k], v); + fs->nk++; + luaC_barrier(L, f, v); + return k; +} + + +/* +** Add a string to list of constants and return its index. +*/ +int luaK_stringK (FuncState *fs, TString *s) { + TValue o; + setsvalue(fs->ls->L, &o, s); + return addk(fs, &o, &o); /* use string itself as key */ +} + + +/* +** Add an integer to list of constants and return its index. +** Integers use userdata as keys to avoid collision with floats with +** same value; conversion to 'void*' is used only for hashing, so there +** are no "precision" problems. +*/ +int luaK_intK (FuncState *fs, lua_Integer n) { + TValue k, o; + setpvalue(&k, cast(void*, cast(size_t, n))); + setivalue(&o, n); + return addk(fs, &k, &o); +} + +/* +** Add a float to list of constants and return its index. +*/ +static int luaK_numberK (FuncState *fs, lua_Number r) { + TValue o; + setfltvalue(&o, r); + return addk(fs, &o, &o); /* use number itself as key */ +} + + +/* +** Add a boolean to list of constants and return its index. +*/ +static int boolK (FuncState *fs, int b) { + TValue o; + setbvalue(&o, b); + return addk(fs, &o, &o); /* use boolean itself as key */ +} + + +/* +** Add nil to list of constants and return its index. +*/ +static int nilK (FuncState *fs) { + TValue k, v; + setnilvalue(&v); + /* cannot use nil as key; instead use table itself to represent nil */ + sethvalue(fs->ls->L, &k, fs->ls->h); + return addk(fs, &k, &v); +} + + +/* +** Fix an expression to return the number of results 'nresults'. +** Either 'e' is a multi-ret expression (function call or vararg) +** or 'nresults' is LUA_MULTRET (as any expression can satisfy that). +*/ +void luaK_setreturns (FuncState *fs, expdesc *e, int nresults) { + if (e->k == VCALL) { /* expression is an open function call? */ + SETARG_C(getinstruction(fs, e), nresults + 1); + } + else if (e->k == VVARARG) { + Instruction *pc = &getinstruction(fs, e); + SETARG_B(*pc, nresults + 1); + SETARG_A(*pc, fs->freereg); + luaK_reserveregs(fs, 1); + } + else lua_assert(nresults == LUA_MULTRET); +} + + +/* +** Fix an expression to return one result. +** If expression is not a multi-ret expression (function call or +** vararg), it already returns one result, so nothing needs to be done. +** Function calls become VNONRELOC expressions (as its result comes +** fixed in the base register of the call), while vararg expressions +** become VRELOCABLE (as OP_VARARG puts its results where it wants). +** (Calls are created returning one result, so that does not need +** to be fixed.) +*/ +void luaK_setoneret (FuncState *fs, expdesc *e) { + if (e->k == VCALL) { /* expression is an open function call? */ + /* already returns 1 value */ + lua_assert(GETARG_C(getinstruction(fs, e)) == 2); + e->k = VNONRELOC; /* result has fixed position */ + e->u.info = GETARG_A(getinstruction(fs, e)); + } + else if (e->k == VVARARG) { + SETARG_B(getinstruction(fs, e), 2); + e->k = VRELOCABLE; /* can relocate its simple result */ + } +} + + +/* +** Ensure that expression 'e' is not a variable. +*/ +void luaK_dischargevars (FuncState *fs, expdesc *e) { + switch (e->k) { + case VLOCAL: { /* already in a register */ + e->k = VNONRELOC; /* becomes a non-relocatable value */ + break; + } + case VUPVAL: { /* move value to some (pending) register */ + e->u.info = luaK_codeABC(fs, OP_GETUPVAL, 0, e->u.info, 0); + e->k = VRELOCABLE; + break; + } + case VINDEXED: { + OpCode op; + freereg(fs, e->u.ind.idx); + if (e->u.ind.vt == VLOCAL) { /* is 't' in a register? */ + freereg(fs, e->u.ind.t); + op = OP_GETTABLE; + } + else { + lua_assert(e->u.ind.vt == VUPVAL); + op = OP_GETTABUP; /* 't' is in an upvalue */ + } + e->u.info = luaK_codeABC(fs, op, 0, e->u.ind.t, e->u.ind.idx); + e->k = VRELOCABLE; + break; + } + case VVARARG: case VCALL: { + luaK_setoneret(fs, e); + break; + } + default: break; /* there is one value available (somewhere) */ + } +} + + +/* +** Ensures expression value is in register 'reg' (and therefore +** 'e' will become a non-relocatable expression). +*/ +static void discharge2reg (FuncState *fs, expdesc *e, int reg) { + luaK_dischargevars(fs, e); + switch (e->k) { + case VNIL: { + luaK_nil(fs, reg, 1); + break; + } + case VFALSE: case VTRUE: { + luaK_codeABC(fs, OP_LOADBOOL, reg, e->k == VTRUE, 0); + break; + } + case VK: { + luaK_codek(fs, reg, e->u.info); + break; + } + case VKFLT: { + luaK_codek(fs, reg, luaK_numberK(fs, e->u.nval)); + break; + } + case VKINT: { + luaK_codek(fs, reg, luaK_intK(fs, e->u.ival)); + break; + } + case VRELOCABLE: { + Instruction *pc = &getinstruction(fs, e); + SETARG_A(*pc, reg); /* instruction will put result in 'reg' */ + break; + } + case VNONRELOC: { + if (reg != e->u.info) + luaK_codeABC(fs, OP_MOVE, reg, e->u.info, 0); + break; + } + default: { + lua_assert(e->k == VJMP); + return; /* nothing to do... */ + } + } + e->u.info = reg; + e->k = VNONRELOC; +} + + +/* +** Ensures expression value is in any register. +*/ +static void discharge2anyreg (FuncState *fs, expdesc *e) { + if (e->k != VNONRELOC) { /* no fixed register yet? */ + luaK_reserveregs(fs, 1); /* get a register */ + discharge2reg(fs, e, fs->freereg-1); /* put value there */ + } +} + + +static int code_loadbool (FuncState *fs, int A, int b, int jump) { + luaK_getlabel(fs); /* those instructions may be jump targets */ + return luaK_codeABC(fs, OP_LOADBOOL, A, b, jump); +} + + +/* +** check whether list has any jump that do not produce a value +** or produce an inverted value +*/ +static int need_value (FuncState *fs, int list) { + for (; list != NO_JUMP; list = getjump(fs, list)) { + Instruction i = *getjumpcontrol(fs, list); + if (GET_OPCODE(i) != OP_TESTSET) return 1; + } + return 0; /* not found */ +} + + +/* +** Ensures final expression result (including results from its jump +** lists) is in register 'reg'. +** If expression has jumps, need to patch these jumps either to +** its final position or to "load" instructions (for those tests +** that do not produce values). +*/ +static void exp2reg (FuncState *fs, expdesc *e, int reg) { + discharge2reg(fs, e, reg); + if (e->k == VJMP) /* expression itself is a test? */ + luaK_concat(fs, &e->t, e->u.info); /* put this jump in 't' list */ + if (hasjumps(e)) { + int final; /* position after whole expression */ + int p_f = NO_JUMP; /* position of an eventual LOAD false */ + int p_t = NO_JUMP; /* position of an eventual LOAD true */ + if (need_value(fs, e->t) || need_value(fs, e->f)) { + int fj = (e->k == VJMP) ? NO_JUMP : luaK_jump(fs); + p_f = code_loadbool(fs, reg, 0, 1); + p_t = code_loadbool(fs, reg, 1, 0); + luaK_patchtohere(fs, fj); + } + final = luaK_getlabel(fs); + patchlistaux(fs, e->f, final, reg, p_f); + patchlistaux(fs, e->t, final, reg, p_t); + } + e->f = e->t = NO_JUMP; + e->u.info = reg; + e->k = VNONRELOC; +} + + +/* +** Ensures final expression result (including results from its jump +** lists) is in next available register. +*/ +void luaK_exp2nextreg (FuncState *fs, expdesc *e) { + luaK_dischargevars(fs, e); + freeexp(fs, e); + luaK_reserveregs(fs, 1); + exp2reg(fs, e, fs->freereg - 1); +} + + +/* +** Ensures final expression result (including results from its jump +** lists) is in some (any) register and return that register. +*/ +int luaK_exp2anyreg (FuncState *fs, expdesc *e) { + luaK_dischargevars(fs, e); + if (e->k == VNONRELOC) { /* expression already has a register? */ + if (!hasjumps(e)) /* no jumps? */ + return e->u.info; /* result is already in a register */ + if (e->u.info >= fs->nactvar) { /* reg. is not a local? */ + exp2reg(fs, e, e->u.info); /* put final result in it */ + return e->u.info; + } + } + luaK_exp2nextreg(fs, e); /* otherwise, use next available register */ + return e->u.info; +} + + +/* +** Ensures final expression result is either in a register or in an +** upvalue. +*/ +void luaK_exp2anyregup (FuncState *fs, expdesc *e) { + if (e->k != VUPVAL || hasjumps(e)) + luaK_exp2anyreg(fs, e); +} + + +/* +** Ensures final expression result is either in a register or it is +** a constant. +*/ +void luaK_exp2val (FuncState *fs, expdesc *e) { + if (hasjumps(e)) + luaK_exp2anyreg(fs, e); + else + luaK_dischargevars(fs, e); +} + + +/* +** Ensures final expression result is in a valid R/K index +** (that is, it is either in a register or in 'k' with an index +** in the range of R/K indices). +** Returns R/K index. +*/ +int luaK_exp2RK (FuncState *fs, expdesc *e) { + luaK_exp2val(fs, e); + switch (e->k) { /* move constants to 'k' */ + case VTRUE: e->u.info = boolK(fs, 1); goto vk; + case VFALSE: e->u.info = boolK(fs, 0); goto vk; + case VNIL: e->u.info = nilK(fs); goto vk; + case VKINT: e->u.info = luaK_intK(fs, e->u.ival); goto vk; + case VKFLT: e->u.info = luaK_numberK(fs, e->u.nval); goto vk; + case VK: + vk: + e->k = VK; + if (e->u.info <= MAXINDEXRK) /* constant fits in 'argC'? */ + return RKASK(e->u.info); + else break; + default: break; + } + /* not a constant in the right range: put it in a register */ + return luaK_exp2anyreg(fs, e); +} + + +/* +** Generate code to store result of expression 'ex' into variable 'var'. +*/ +void luaK_storevar (FuncState *fs, expdesc *var, expdesc *ex) { + switch (var->k) { + case VLOCAL: { + freeexp(fs, ex); + exp2reg(fs, ex, var->u.info); /* compute 'ex' into proper place */ + return; + } + case VUPVAL: { + int e = luaK_exp2anyreg(fs, ex); + luaK_codeABC(fs, OP_SETUPVAL, e, var->u.info, 0); + break; + } + case VINDEXED: { + OpCode op = (var->u.ind.vt == VLOCAL) ? OP_SETTABLE : OP_SETTABUP; + int e = luaK_exp2RK(fs, ex); + luaK_codeABC(fs, op, var->u.ind.t, var->u.ind.idx, e); + break; + } + default: lua_assert(0); /* invalid var kind to store */ + } + freeexp(fs, ex); +} + + +/* +** Emit SELF instruction (convert expression 'e' into 'e:key(e,'). +*/ +void luaK_self (FuncState *fs, expdesc *e, expdesc *key) { + int ereg; + luaK_exp2anyreg(fs, e); + ereg = e->u.info; /* register where 'e' was placed */ + freeexp(fs, e); + e->u.info = fs->freereg; /* base register for op_self */ + e->k = VNONRELOC; /* self expression has a fixed register */ + luaK_reserveregs(fs, 2); /* function and 'self' produced by op_self */ + luaK_codeABC(fs, OP_SELF, e->u.info, ereg, luaK_exp2RK(fs, key)); + freeexp(fs, key); +} + + +/* +** Negate condition 'e' (where 'e' is a comparison). +*/ +static void negatecondition (FuncState *fs, expdesc *e) { + Instruction *pc = getjumpcontrol(fs, e->u.info); + lua_assert(testTMode(GET_OPCODE(*pc)) && GET_OPCODE(*pc) != OP_TESTSET && + GET_OPCODE(*pc) != OP_TEST); + SETARG_A(*pc, !(GETARG_A(*pc))); +} + + +/* +** Emit instruction to jump if 'e' is 'cond' (that is, if 'cond' +** is true, code will jump if 'e' is true.) Return jump position. +** Optimize when 'e' is 'not' something, inverting the condition +** and removing the 'not'. +*/ +static int jumponcond (FuncState *fs, expdesc *e, int cond) { + if (e->k == VRELOCABLE) { + Instruction ie = getinstruction(fs, e); + if (GET_OPCODE(ie) == OP_NOT) { + fs->pc--; /* remove previous OP_NOT */ + return condjump(fs, OP_TEST, GETARG_B(ie), 0, !cond); + } + /* else go through */ + } + discharge2anyreg(fs, e); + freeexp(fs, e); + return condjump(fs, OP_TESTSET, NO_REG, e->u.info, cond); +} + + +/* +** Emit code to go through if 'e' is true, jump otherwise. +*/ +void luaK_goiftrue (FuncState *fs, expdesc *e) { + int pc; /* pc of new jump */ + luaK_dischargevars(fs, e); + switch (e->k) { + case VJMP: { /* condition? */ + negatecondition(fs, e); /* jump when it is false */ + pc = e->u.info; /* save jump position */ + break; + } + case VK: case VKFLT: case VKINT: case VTRUE: { + pc = NO_JUMP; /* always true; do nothing */ + break; + } + default: { + pc = jumponcond(fs, e, 0); /* jump when false */ + break; + } + } + luaK_concat(fs, &e->f, pc); /* insert new jump in false list */ + luaK_patchtohere(fs, e->t); /* true list jumps to here (to go through) */ + e->t = NO_JUMP; +} + + +/* +** Emit code to go through if 'e' is false, jump otherwise. +*/ +void luaK_goiffalse (FuncState *fs, expdesc *e) { + int pc; /* pc of new jump */ + luaK_dischargevars(fs, e); + switch (e->k) { + case VJMP: { + pc = e->u.info; /* already jump if true */ + break; + } + case VNIL: case VFALSE: { + pc = NO_JUMP; /* always false; do nothing */ + break; + } + default: { + pc = jumponcond(fs, e, 1); /* jump if true */ + break; + } + } + luaK_concat(fs, &e->t, pc); /* insert new jump in 't' list */ + luaK_patchtohere(fs, e->f); /* false list jumps to here (to go through) */ + e->f = NO_JUMP; +} + + +/* +** Code 'not e', doing constant folding. +*/ +static void codenot (FuncState *fs, expdesc *e) { + luaK_dischargevars(fs, e); + switch (e->k) { + case VNIL: case VFALSE: { + e->k = VTRUE; /* true == not nil == not false */ + break; + } + case VK: case VKFLT: case VKINT: case VTRUE: { + e->k = VFALSE; /* false == not "x" == not 0.5 == not 1 == not true */ + break; + } + case VJMP: { + negatecondition(fs, e); + break; + } + case VRELOCABLE: + case VNONRELOC: { + discharge2anyreg(fs, e); + freeexp(fs, e); + e->u.info = luaK_codeABC(fs, OP_NOT, 0, e->u.info, 0); + e->k = VRELOCABLE; + break; + } + default: lua_assert(0); /* cannot happen */ + } + /* interchange true and false lists */ + { int temp = e->f; e->f = e->t; e->t = temp; } + removevalues(fs, e->f); /* values are useless when negated */ + removevalues(fs, e->t); +} + + +/* +** Create expression 't[k]'. 't' must have its final result already in a +** register or upvalue. +*/ +void luaK_indexed (FuncState *fs, expdesc *t, expdesc *k) { + lua_assert(!hasjumps(t) && (vkisinreg(t->k) || t->k == VUPVAL)); + t->u.ind.t = t->u.info; /* register or upvalue index */ + t->u.ind.idx = luaK_exp2RK(fs, k); /* R/K index for key */ + t->u.ind.vt = (t->k == VUPVAL) ? VUPVAL : VLOCAL; + t->k = VINDEXED; +} + + +/* +** Return false if folding can raise an error. +** Bitwise operations need operands convertible to integers; division +** operations cannot have 0 as divisor. +*/ +static int validop (int op, TValue *v1, TValue *v2) { + switch (op) { + case LUA_OPBAND: case LUA_OPBOR: case LUA_OPBXOR: + case LUA_OPSHL: case LUA_OPSHR: case LUA_OPBNOT: { /* conversion errors */ + lua_Integer i; + return (tointeger(v1, &i) && tointeger(v2, &i)); + } + case LUA_OPDIV: case LUA_OPIDIV: case LUA_OPMOD: /* division by 0 */ + return (nvalue(v2) != 0); + default: return 1; /* everything else is valid */ + } +} + + +/* +** Try to "constant-fold" an operation; return 1 iff successful. +** (In this case, 'e1' has the final result.) +*/ +static int constfolding (FuncState *fs, int op, expdesc *e1, + const expdesc *e2) { + TValue v1, v2, res; + if (!tonumeral(e1, &v1) || !tonumeral(e2, &v2) || !validop(op, &v1, &v2)) + return 0; /* non-numeric operands or not safe to fold */ + luaO_arith(fs->ls->L, op, &v1, &v2, &res); /* does operation */ + if (ttisinteger(&res)) { + e1->k = VKINT; + e1->u.ival = ivalue(&res); + } + else { /* folds neither NaN nor 0.0 (to avoid problems with -0.0) */ + lua_Number n = fltvalue(&res); + if (luai_numisnan(n) || n == 0) + return 0; + e1->k = VKFLT; + e1->u.nval = n; + } + return 1; +} + + +/* +** Emit code for unary expressions that "produce values" +** (everything but 'not'). +** Expression to produce final result will be encoded in 'e'. +*/ +static void codeunexpval (FuncState *fs, OpCode op, expdesc *e, int line) { + int r = luaK_exp2anyreg(fs, e); /* opcodes operate only on registers */ + freeexp(fs, e); + e->u.info = luaK_codeABC(fs, op, 0, r, 0); /* generate opcode */ + e->k = VRELOCABLE; /* all those operations are relocatable */ + luaK_fixline(fs, line); +} + + +/* +** Emit code for binary expressions that "produce values" +** (everything but logical operators 'and'/'or' and comparison +** operators). +** Expression to produce final result will be encoded in 'e1'. +** Because 'luaK_exp2RK' can free registers, its calls must be +** in "stack order" (that is, first on 'e2', which may have more +** recent registers to be released). +*/ +static void codebinexpval (FuncState *fs, OpCode op, + expdesc *e1, expdesc *e2, int line) { + int rk2 = luaK_exp2RK(fs, e2); /* both operands are "RK" */ + int rk1 = luaK_exp2RK(fs, e1); + freeexps(fs, e1, e2); + e1->u.info = luaK_codeABC(fs, op, 0, rk1, rk2); /* generate opcode */ + e1->k = VRELOCABLE; /* all those operations are relocatable */ + luaK_fixline(fs, line); +} + + +/* +** Emit code for comparisons. +** 'e1' was already put in R/K form by 'luaK_infix'. +*/ +static void codecomp (FuncState *fs, BinOpr opr, expdesc *e1, expdesc *e2) { + int rk1 = (e1->k == VK) ? RKASK(e1->u.info) + : check_exp(e1->k == VNONRELOC, e1->u.info); + int rk2 = luaK_exp2RK(fs, e2); + freeexps(fs, e1, e2); + switch (opr) { + case OPR_NE: { /* '(a ~= b)' ==> 'not (a == b)' */ + e1->u.info = condjump(fs, OP_EQ, 0, rk1, rk2); + break; + } + case OPR_GT: case OPR_GE: { + /* '(a > b)' ==> '(b < a)'; '(a >= b)' ==> '(b <= a)' */ + OpCode op = cast(OpCode, (opr - OPR_NE) + OP_EQ); + e1->u.info = condjump(fs, op, 1, rk2, rk1); /* invert operands */ + break; + } + default: { /* '==', '<', '<=' use their own opcodes */ + OpCode op = cast(OpCode, (opr - OPR_EQ) + OP_EQ); + e1->u.info = condjump(fs, op, 1, rk1, rk2); + break; + } + } + e1->k = VJMP; +} + + +/* +** Apply prefix operation 'op' to expression 'e'. +*/ +void luaK_prefix (FuncState *fs, UnOpr op, expdesc *e, int line) { + static const expdesc ef = {VKINT, {0}, NO_JUMP, NO_JUMP}; + switch (op) { + case OPR_MINUS: case OPR_BNOT: /* use 'ef' as fake 2nd operand */ + if (constfolding(fs, op + LUA_OPUNM, e, &ef)) + break; + /* FALLTHROUGH */ + case OPR_LEN: + codeunexpval(fs, cast(OpCode, op + OP_UNM), e, line); + break; + case OPR_NOT: codenot(fs, e); break; + default: lua_assert(0); + } +} + + +/* +** Process 1st operand 'v' of binary operation 'op' before reading +** 2nd operand. +*/ +void luaK_infix (FuncState *fs, BinOpr op, expdesc *v) { + switch (op) { + case OPR_AND: { + luaK_goiftrue(fs, v); /* go ahead only if 'v' is true */ + break; + } + case OPR_OR: { + luaK_goiffalse(fs, v); /* go ahead only if 'v' is false */ + break; + } + case OPR_CONCAT: { + luaK_exp2nextreg(fs, v); /* operand must be on the 'stack' */ + break; + } + case OPR_ADD: case OPR_SUB: + case OPR_MUL: case OPR_DIV: case OPR_IDIV: + case OPR_MOD: case OPR_POW: + case OPR_BAND: case OPR_BOR: case OPR_BXOR: + case OPR_SHL: case OPR_SHR: { + if (!tonumeral(v, NULL)) + luaK_exp2RK(fs, v); + /* else keep numeral, which may be folded with 2nd operand */ + break; + } + default: { + luaK_exp2RK(fs, v); + break; + } + } +} + + +/* +** Finalize code for binary operation, after reading 2nd operand. +** For '(a .. b .. c)' (which is '(a .. (b .. c))', because +** concatenation is right associative), merge second CONCAT into first +** one. +*/ +void luaK_posfix (FuncState *fs, BinOpr op, + expdesc *e1, expdesc *e2, int line) { + switch (op) { + case OPR_AND: { + lua_assert(e1->t == NO_JUMP); /* list closed by 'luK_infix' */ + luaK_dischargevars(fs, e2); + luaK_concat(fs, &e2->f, e1->f); + *e1 = *e2; + break; + } + case OPR_OR: { + lua_assert(e1->f == NO_JUMP); /* list closed by 'luK_infix' */ + luaK_dischargevars(fs, e2); + luaK_concat(fs, &e2->t, e1->t); + *e1 = *e2; + break; + } + case OPR_CONCAT: { + luaK_exp2val(fs, e2); + if (e2->k == VRELOCABLE && + GET_OPCODE(getinstruction(fs, e2)) == OP_CONCAT) { + lua_assert(e1->u.info == GETARG_B(getinstruction(fs, e2))-1); + freeexp(fs, e1); + SETARG_B(getinstruction(fs, e2), e1->u.info); + e1->k = VRELOCABLE; e1->u.info = e2->u.info; + } + else { + luaK_exp2nextreg(fs, e2); /* operand must be on the 'stack' */ + codebinexpval(fs, OP_CONCAT, e1, e2, line); + } + break; + } + case OPR_ADD: case OPR_SUB: case OPR_MUL: case OPR_DIV: + case OPR_IDIV: case OPR_MOD: case OPR_POW: + case OPR_BAND: case OPR_BOR: case OPR_BXOR: + case OPR_SHL: case OPR_SHR: |
