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# Copyright: 2005 Gentoo Foundation
# Author(s): Brian Harring (ferringb@gentoo.org)
# License: GPL2
# $Id$
import UserDict
class ProtectedDict(UserDict.DictMixin):
"""
given an initial dict, this wraps that dict storing changes in a secondary dict, protecting
the underlying dict from changes
"""
__slots__=("orig","new","blacklist")
def __init__(self, orig):
self.orig = orig
self.new = {}
self.blacklist = {}
def __setitem__(self, key, val):
self.new[key] = val
if key in self.blacklist:
del self.blacklist[key]
def __getitem__(self, key):
if key in self.new:
return self.new[key]
if key in self.blacklist:
raise KeyError(key)
return self.orig[key]
def __delitem__(self, key):
if key in self.new:
del self.new[key]
elif key in self.orig:
if key not in self.blacklist:
self.blacklist[key] = True
return
raise KeyError(key)
def __iter__(self):
for k in self.new.iterkeys():
yield k
for k in self.orig.iterkeys():
if k not in self.blacklist and k not in self.new:
yield k
def keys(self):
return list(self.__iter__())
def has_key(self, key):
return key in self.new or (key not in self.blacklist and key in self.orig)
class LazyLoad(UserDict.DictMixin):
"""
Lazy loading of values for a dict
"""
__slots__=("pull", "d")
def __init__(self, pull_items_func, initial_items=[]):
self.d = {}
for k, v in initial_items:
self.d[k] = v
self.pull = pull_items_func
def __getitem__(self, key):
if key in self.d:
return self.d[key]
elif self.pull != None:
self.d.update(self.pull())
self.pull = None
return self.d[key]
def __iter__(self):
return iter(self.keys())
def keys(self):
if self.pull != None:
self.d.update(self.pull())
self.pull = None
return self.d.keys()
def has_key(self, key):
return key in self
def __contains__(self, key):
if key in self.d:
return True
elif self.pull != None:
self.d.update(self.pull())
self.pull = None
return key in self.d
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