| <?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]'); |
| } |
| } |
| } |
| |
| } |
