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Diffstat (limited to 'phpBB/includes/diff/engine.php')
| -rw-r--r-- | phpBB/includes/diff/engine.php | 554 |
1 files changed, 554 insertions, 0 deletions
diff --git a/phpBB/includes/diff/engine.php b/phpBB/includes/diff/engine.php new file mode 100644 index 0000000000..982149457d --- /dev/null +++ b/phpBB/includes/diff/engine.php @@ -0,0 +1,554 @@ +<?php +/** +* +* @package diff +* @version $Id$ +* @copyright (c) 2006 phpBB Group +* @license http://opensource.org/licenses/gpl-license.php GNU Public License +* +*/ + +/** +* @ignore +*/ +if (!defined('IN_PHPBB')) +{ + exit; +} + +/** +* Code from pear.php.net, Text_Diff-1.1.0 package +* http://pear.php.net/package/Text_Diff/ (native engine) +* +* Modified by phpBB Group to meet our coding standards +* and being able to integrate into phpBB +* +* Class used internally by Text_Diff to actually compute the diffs. This +* class is implemented using native PHP code. +* +* The algorithm used here is mostly lifted from the perl module +* Algorithm::Diff (version 1.06) by Ned Konz, which is available at: +* http://www.perl.com/CPAN/authors/id/N/NE/NEDKONZ/Algorithm-Diff-1.06.zip +* +* More ideas are taken from: http://www.ics.uci.edu/~eppstein/161/960229.html +* +* Some ideas (and a bit of code) are taken from analyze.c, of GNU +* diffutils-2.7, which can be found at: +* ftp://gnudist.gnu.org/pub/gnu/diffutils/diffutils-2.7.tar.gz +* +* Some ideas (subdivision by NCHUNKS > 2, and some optimizations) are from +* Geoffrey T. Dairiki <dairiki@dairiki.org>. The original PHP version of this +* code was written by him, and is used/adapted with his permission. +* +* Copyright 2004-2008 The Horde Project (http://www.horde.org/) +* +* @author Geoffrey T. Dairiki <dairiki@dairiki.org> +* @package diff +* +* @access private +*/ +class diff_engine +{ + /** + * If set to true we trim all lines before we compare them. This ensures that sole space/tab changes do not trigger diffs. + */ + var $skip_whitespace_changes = true; + + function diff(&$from_lines, &$to_lines, $preserve_cr = true) + { + // Remove empty lines... + // If preserve_cr is true, we basically only change \r\n and bare \r to \n to get the same carriage returns for both files + // If it is false, we try to only use \n once per line and ommit all empty lines to be able to get a proper data diff + + if (is_array($from_lines)) + { + $from_lines = implode("\n", $from_lines); + } + + if (is_array($to_lines)) + { + $to_lines = implode("\n", $to_lines); + } + + if ($preserve_cr) + { + $from_lines = explode("\n", str_replace("\r", "\n", str_replace("\r\n", "\n", $from_lines))); + $to_lines = explode("\n", str_replace("\r", "\n", str_replace("\r\n", "\n", $to_lines))); + } + else + { + $from_lines = explode("\n", preg_replace('#[\n\r]+#', "\n", $from_lines)); + $to_lines = explode("\n", preg_replace('#[\n\r]+#', "\n", $to_lines)); + } + + $n_from = sizeof($from_lines); + $n_to = sizeof($to_lines); + + $this->xchanged = $this->ychanged = $this->xv = $this->yv = $this->xind = $this->yind = array(); + unset($this->seq, $this->in_seq, $this->lcs); + + // Skip leading common lines. + for ($skip = 0; $skip < $n_from && $skip < $n_to; $skip++) + { + if (trim($from_lines[$skip]) !== trim($to_lines[$skip])) + { + break; + } + $this->xchanged[$skip] = $this->ychanged[$skip] = false; + } + + // Skip trailing common lines. + $xi = $n_from; + $yi = $n_to; + + for ($endskip = 0; --$xi > $skip && --$yi > $skip; $endskip++) + { + if (trim($from_lines[$xi]) !== trim($to_lines[$yi])) + { + break; + } + $this->xchanged[$xi] = $this->ychanged[$yi] = false; + } + + // Ignore lines which do not exist in both files. + for ($xi = $skip; $xi < $n_from - $endskip; $xi++) + { + if ($this->skip_whitespace_changes) $xhash[trim($from_lines[$xi])] = 1; else $xhash[$from_lines[$xi]] = 1; + } + + for ($yi = $skip; $yi < $n_to - $endskip; $yi++) + { + $line = ($this->skip_whitespace_changes) ? trim($to_lines[$yi]) : $to_lines[$yi]; + + if (($this->ychanged[$yi] = empty($xhash[$line]))) + { + continue; + } + $yhash[$line] = 1; + $this->yv[] = $line; + $this->yind[] = $yi; + } + + for ($xi = $skip; $xi < $n_from - $endskip; $xi++) + { + $line = ($this->skip_whitespace_changes) ? trim($from_lines[$xi]) : $from_lines[$xi]; + + if (($this->xchanged[$xi] = empty($yhash[$line]))) + { + continue; + } + $this->xv[] = $line; + $this->xind[] = $xi; + } + + // Find the LCS. + $this->_compareseq(0, sizeof($this->xv), 0, sizeof($this->yv)); + + // Merge edits when possible. + if ($this->skip_whitespace_changes) + { + $from_lines_clean = array_map('trim', $from_lines); + $to_lines_clean = array_map('trim', $to_lines); + + $this->_shift_boundaries($from_lines_clean, $this->xchanged, $this->ychanged); + $this->_shift_boundaries($to_lines_clean, $this->ychanged, $this->xchanged); + + unset($from_lines_clean, $to_lines_clean); + } + else + { + $this->_shift_boundaries($from_lines, $this->xchanged, $this->ychanged); + $this->_shift_boundaries($to_lines, $this->ychanged, $this->xchanged); + } + + // Compute the edit operations. + $edits = array(); + $xi = $yi = 0; + + while ($xi < $n_from || $yi < $n_to) + { + // Skip matching "snake". + $copy = array(); + + while ($xi < $n_from && $yi < $n_to && !$this->xchanged[$xi] && !$this->ychanged[$yi]) + { + $copy[] = $from_lines[$xi++]; + $yi++; + } + + if ($copy) + { + $edits[] = new diff_op_copy($copy); + } + + // Find deletes & adds. + $delete = array(); + while ($xi < $n_from && $this->xchanged[$xi]) + { + $delete[] = $from_lines[$xi++]; + } + + $add = array(); + while ($yi < $n_to && $this->ychanged[$yi]) + { + $add[] = $to_lines[$yi++]; + } + + if ($delete && $add) + { + $edits[] = new diff_op_change($delete, $add); + } + else if ($delete) + { + $edits[] = new diff_op_delete($delete); + } + else if ($add) + { + $edits[] = new diff_op_add($add); + } + } + + return $edits; + } + + /** + * Divides the Largest Common Subsequence (LCS) of the sequences (XOFF, + * XLIM) and (YOFF, YLIM) into NCHUNKS approximately equally sized segments. + * + * Returns (LCS, PTS). LCS is the length of the LCS. PTS is an array of + * NCHUNKS+1 (X, Y) indexes giving the diving points between sub + * sequences. The first sub-sequence is contained in (X0, X1), (Y0, Y1), + * the second in (X1, X2), (Y1, Y2) and so on. Note that (X0, Y0) == + * (XOFF, YOFF) and (X[NCHUNKS], Y[NCHUNKS]) == (XLIM, YLIM). + * + * This function assumes that the first lines of the specified portions of + * the two files do not match, and likewise that the last lines do not + * match. The caller must trim matching lines from the beginning and end + * of the portions it is going to specify. + */ + function _diag($xoff, $xlim, $yoff, $ylim, $nchunks) + { + $flip = false; + + if ($xlim - $xoff > $ylim - $yoff) + { + // Things seems faster (I'm not sure I understand why) when the shortest sequence is in X. + $flip = true; + list($xoff, $xlim, $yoff, $ylim) = array($yoff, $ylim, $xoff, $xlim); + } + + if ($flip) + { + for ($i = $ylim - 1; $i >= $yoff; $i--) + { + $ymatches[$this->xv[$i]][] = $i; + } + } + else + { + for ($i = $ylim - 1; $i >= $yoff; $i--) + { + $ymatches[$this->yv[$i]][] = $i; + } + } + + $this->lcs = 0; + $this->seq[0]= $yoff - 1; + $this->in_seq = array(); + $ymids[0] = array(); + + $numer = $xlim - $xoff + $nchunks - 1; + $x = $xoff; + + for ($chunk = 0; $chunk < $nchunks; $chunk++) + { + if ($chunk > 0) + { + for ($i = 0; $i <= $this->lcs; $i++) + { + $ymids[$i][$chunk - 1] = $this->seq[$i]; + } + } + + $x1 = $xoff + (int)(($numer + ($xlim - $xoff) * $chunk) / $nchunks); + + for (; $x < $x1; $x++) + { + $line = $flip ? $this->yv[$x] : $this->xv[$x]; + if (empty($ymatches[$line])) + { + continue; + } + $matches = $ymatches[$line]; + + reset($matches); + while (list(, $y) = each($matches)) + { + if (empty($this->in_seq[$y])) + { + $k = $this->_lcs_pos($y); + $ymids[$k] = $ymids[$k - 1]; + break; + } + } + + // no reset() here + while (list(, $y) = each($matches)) + { + if ($y > $this->seq[$k - 1]) + { + // Optimization: this is a common case: next match is just replacing previous match. + $this->in_seq[$this->seq[$k]] = false; + $this->seq[$k] = $y; + $this->in_seq[$y] = 1; + } + else if (empty($this->in_seq[$y])) + { + $k = $this->_lcs_pos($y); + $ymids[$k] = $ymids[$k - 1]; + } + } + } + } + + $seps[] = $flip ? array($yoff, $xoff) : array($xoff, $yoff); + $ymid = $ymids[$this->lcs]; + + for ($n = 0; $n < $nchunks - 1; $n++) + { + $x1 = $xoff + (int)(($numer + ($xlim - $xoff) * $n) / $nchunks); + $y1 = $ymid[$n] + 1; + $seps[] = $flip ? array($y1, $x1) : array($x1, $y1); + } + $seps[] = $flip ? array($ylim, $xlim) : array($xlim, $ylim); + + return array($this->lcs, $seps); + } + + function _lcs_pos($ypos) + { + $end = $this->lcs; + + if ($end == 0 || $ypos > $this->seq[$end]) + { + $this->seq[++$this->lcs] = $ypos; + $this->in_seq[$ypos] = 1; + return $this->lcs; + } + + $beg = 1; + while ($beg < $end) + { + $mid = (int)(($beg + $end) / 2); + if ($ypos > $this->seq[$mid]) + { + $beg = $mid + 1; + } + else + { + $end = $mid; + } + } + + $this->in_seq[$this->seq[$end]] = false; + $this->seq[$end] = $ypos; + $this->in_seq[$ypos] = 1; + + return $end; + } + + /** + * Finds LCS of two sequences. + * + * The results are recorded in the vectors $this->{x,y}changed[], by + * storing a 1 in the element for each line that is an insertion or + * deletion (ie. is not in the LCS). + * + * The subsequence of file 0 is (XOFF, XLIM) and likewise for file 1. + * + * Note that XLIM, YLIM are exclusive bounds. All line numbers are + * origin-0 and discarded lines are not counted. + */ + function _compareseq($xoff, $xlim, $yoff, $ylim) + { + // Slide down the bottom initial diagonal. + while ($xoff < $xlim && $yoff < $ylim && $this->xv[$xoff] == $this->yv[$yoff]) + { + ++$xoff; + ++$yoff; + } + + // Slide up the top initial diagonal. + while ($xlim > $xoff && $ylim > $yoff && $this->xv[$xlim - 1] == $this->yv[$ylim - 1]) + { + --$xlim; + --$ylim; + } + + if ($xoff == $xlim || $yoff == $ylim) + { + $lcs = 0; + } + else + { + // This is ad hoc but seems to work well. + // $nchunks = sqrt(min($xlim - $xoff, $ylim - $yoff) / 2.5); + // $nchunks = max(2,min(8,(int)$nchunks)); + $nchunks = min(7, $xlim - $xoff, $ylim - $yoff) + 1; + list($lcs, $seps) = $this->_diag($xoff, $xlim, $yoff, $ylim, $nchunks); + } + + if ($lcs == 0) + { + // X and Y sequences have no common subsequence: mark all changed. + while ($yoff < $ylim) + { + $this->ychanged[$this->yind[$yoff++]] = 1; + } + + while ($xoff < $xlim) + { + $this->xchanged[$this->xind[$xoff++]] = 1; + } + } + else + { + // Use the partitions to split this problem into subproblems. + reset($seps); + $pt1 = $seps[0]; + + while ($pt2 = next($seps)) + { + $this->_compareseq($pt1[0], $pt2[0], $pt1[1], $pt2[1]); + $pt1 = $pt2; + } + } + } + + /** + * Adjusts inserts/deletes of identical lines to join changes as much as possible. + * + * We do something when a run of changed lines include a line at one end + * and has an excluded, identical line at the other. We are free to + * choose which identical line is included. 'compareseq' usually chooses + * the one at the beginning, but usually it is cleaner to consider the + * following identical line to be the "change". + * + * This is extracted verbatim from analyze.c (GNU diffutils-2.7). + */ + function _shift_boundaries($lines, &$changed, $other_changed) + { + $i = 0; + $j = 0; + + $len = sizeof($lines); + $other_len = sizeof($other_changed); + + while (1) + { + // Scan forward to find the beginning of another run of + // changes. Also keep track of the corresponding point in the other file. + // + // Throughout this code, $i and $j are adjusted together so that + // the first $i elements of $changed and the first $j elements of + // $other_changed both contain the same number of zeros (unchanged lines). + // + // Furthermore, $j is always kept so that $j == $other_len or $other_changed[$j] == false. + while ($j < $other_len && $other_changed[$j]) + { + $j++; + } + + while ($i < $len && ! $changed[$i]) + { + $i++; + $j++; + + while ($j < $other_len && $other_changed[$j]) + { + $j++; + } + } + + if ($i == $len) + { + break; + } + + $start = $i; + + // Find the end of this run of changes. + while (++$i < $len && $changed[$i]) + { + continue; + } + + do + { + // Record the length of this run of changes, so that we can later determine whether the run has grown. + $runlength = $i - $start; + + // Move the changed region back, so long as the previous unchanged line matches the last changed one. + // This merges with previous changed regions. + while ($start > 0 && $lines[$start - 1] == $lines[$i - 1]) + { + $changed[--$start] = 1; + $changed[--$i] = false; + + while ($start > 0 && $changed[$start - 1]) + { + $start--; + } + + while ($other_changed[--$j]) + { + continue; + } + } + + // Set CORRESPONDING to the end of the changed run, at the last point where it corresponds to a changed run in the + // other file. CORRESPONDING == LEN means no such point has been found. + $corresponding = $j < $other_len ? $i : $len; + + // Move the changed region forward, so long as the first changed line matches the following unchanged one. + // This merges with following changed regions. + // Do this second, so that if there are no merges, the changed region is moved forward as far as possible. + while ($i < $len && $lines[$start] == $lines[$i]) + { + $changed[$start++] = false; + $changed[$i++] = 1; + + while ($i < $len && $changed[$i]) + { + $i++; + } + + $j++; + if ($j < $other_len && $other_changed[$j]) + { + $corresponding = $i; + while ($j < $other_len && $other_changed[$j]) + { + $j++; + } + } + } + } + while ($runlength != $i - $start); + + // If possible, move the fully-merged run of changes back to a corresponding run in the other file. + while ($corresponding < $i) + { + $changed[--$start] = 1; + $changed[--$i] = 0; + + while ($other_changed[--$j]) + { + continue; + } + } + } + } +} + +?>
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