site_iri: comparison web/wp-includes/Text/Diff/Engine/native.php

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+:03b0d1493584
+<?php
+/**
+* $Horde: framework/Text_Diff/Diff/Engine/native.php,v 1.10 2008/01/04 10:27:53 jan Exp $
+*
+* 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/)
+*
+* See the enclosed file COPYING for license information (LGPL). If you did
+* not receive this file, see http://opensource.org/licenses/lgpl-license.php.
+*
+* @author  Geoffrey T. Dairiki <dairiki@dairiki.org>
+* @package Text_Diff
+*/
+class Text_Diff_Engine_native {
+function diff($from_lines, $to_lines)
+{
+array_walk($from_lines, array('Text_Diff', 'trimNewlines'));
+array_walk($to_lines, array('Text_Diff', 'trimNewlines'));
+$n_from = count($from_lines);
+$n_to = count($to_lines);
+$this->xchanged = $this->ychanged = array();
+$this->xv = $this->yv = array();
+$this->xind = $this->yind = array();
+unset($this->seq);
+unset($this->in_seq);
+unset($this->lcs);
+// Skip leading common lines.
+for ($skip = 0; $skip < $n_from && $skip < $n_to; $skip++) {
+if ($from_lines[$skip] !== $to_lines[$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; $endskip++) {
+if ($from_lines[$xi] !== $to_lines[$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; $xi++) {
+$xhash[$from_lines[$xi]] = 1;
+}
+for ($yi = $skip; $yi < $n_to - $endskip; $yi++) {
+$line = $to_lines[$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 = $from_lines[$xi];
+if (($this->xchanged[$xi] = empty($yhash[$line]))) {
+continue;
+}
+$this->xv[] = $line;
+$this->xind[] = $xi;
+}
+// Find the LCS.
+$this->_compareseq(0, count($this->xv), 0, count($this->yv));
+// Merge edits when possible.
+$this->_shiftBoundaries($from_lines, $this->xchanged, $this->ychanged);
+$this->_shiftBoundaries($to_lines, $this->ychanged, $this->xchanged);
+// Compute the edit operations.
+$edits = array();
+$xi = $yi = 0;
+while ($xi < $n_from || $yi < $n_to) {
+assert($yi < $n_to || $this->xchanged[$xi]);
+assert($xi < $n_from || $this->ychanged[$yi]);
+// 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) {
+$edits[] = &new Text_Diff_Op_copy($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 Text_Diff_Op_change($delete, $add);
+} elseif ($delete) {
+$edits[] = &new Text_Diff_Op_delete($delete);
+} elseif ($add) {
+$edits[] = &new Text_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 = $this->_lcsPos($y);
+assert($k > 0);
+$ymids[$k] = $ymids[$k - 1];
+break;
+}
+}
+while (list(, $y) = each($matches)) {
+if ($y > $this->seq[$k - 1]) {
+assert($y <= $this->seq[$k]);
+/* 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[$y] = 1;
+} elseif (empty($this->in_seq[$y])) {
+$k = $this->_lcsPos($y);
+assert($k > 0);
+$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, $seps);
+}
+function _lcsPos($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 = $mid;
+}
+}
+assert($ypos != $this->seq[$end]);
+$this->in_seq[$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 = $pt2;
+}
+}
+}
+/**
+* Adjusts inserts/deletes of identical lines to join changes as much as
+* possible.
+*
+* We do something when a run of changed lines include a line at one end
+* and has an excluded, identical line at the other.  We are free to
+* choose which identical line is included.  `compareseq' usually chooses
+* the one at the beginning, but usually it is cleaner to consider the
+* following identical line to be the "change".
+*
+* This is extracted verbatim from analyze.c (GNU diffutils-2.7).
+*/
+function _shiftBoundaries($lines, &$changed, $other_changed)
+{
+$i = 0;
+$j = 0;
+assert('count($lines) == count($changed)');
+$len = count($lines);
+$other_len = count($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]) {
+assert('$j < $other_len && ! $other_changed[$j]');
+$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]) {
+$start--;
+}
+assert('$j > 0');
+while ($other_changed[--$j]) {
+continue;
+}
+assert('$j >= 0 && !$other_changed[$j]');
+}
+/* Set CORRESPONDING to the end of the changed run, at the
+* last point where it corresponds to a changed run in the
+* other file. CORRESPONDING == LEN means no such point has
+* been found. */
+$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]) {
+$i++;
+}
+assert('$j < $other_len && ! $other_changed[$j]');
+$j++;
+if ($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[--$i] = 0;
+assert('$j > 0');
+while ($other_changed[--$j]) {
+continue;
+}
+assert('$j >= 0 && !$other_changed[$j]');
+}
+}
+}
+}

branch	wordpress
changeset 109	03b0d1493584
child 132	4d4862461b8d