Collaboration diagram for _DiffEngine:

Public Member Functions
	diff ($from_lines, $to_lines)

	_line_hash ($line)
	Returns the whole line if it's small enough, or the MD5 hash otherwise. More...

	_diag ($xoff, $xlim, $yoff, $ylim, $nchunks)

	_lcs_pos ($ypos)

	_compareseq ($xoff, $xlim, $yoff, $ylim)

	_shift_boundaries ($lines, &$changed, $other_changed)

Data Fields
const	MAX_XREF_LENGTH = 10000

Detailed Description

Definition at line 830 of file class.WordLevelDiff.php.

Member Function Documentation

◆ _compareseq()

_DiffEngine::_compareseq	(	$xoff,
		$xlim,
		$yoff,
		$ylim
	)

Definition at line 1095 of file class.WordLevelDiff.php.

     {
         $fname = '_DiffEngine::_compareseq';
         //wfProfileIn( $fname );
 
         // 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;
             }

◆ _diag()

_DiffEngine::_diag	(	$xoff,
		$xlim,
		$yoff,
		$ylim,
		$nchunks
	)

Definition at line 966 of file class.WordLevelDiff.php.

References $i, $x, $y, array, and USE_ASSERTS.

     {
         $fname = '_DiffEngine::_diag';
         //wfProfileIn( $fname );
         $flip = false;
 
         if ($xlim - $xoff > $ylim - $yoff) {
             // Things seems faster (I'm not sure I understand why)
             // when the shortest sequence 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; $chunk++) {
             //wfProfileIn( "$fname-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($matches);
                 while (list($junk, $y) = each($matches)) {
                     if (empty($this->in_seq[$y])) {
                         $k = $this->_lcs_pos($y);
                         USE_ASSERTS && assert($k > 0);
                         $ymids[$k] = $ymids[$k-1];
                         break;
                     }
                 }
                 while (list( /* $junk */, $y) = each($matches)) {
                     if ($y > $this->seq[$k-1]) {
                         USE_ASSERTS && 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 = $this->_lcs_pos($y);
                         USE_ASSERTS && assert($k > 0);
                         $ymids[$k] = $ymids[$k-1];
                     }
                 }
             }
             //wfProfileOut( "$fname-chunk" );

◆ _lcs_pos()

_DiffEngine::_lcs_pos ( $ypos )

Definition at line 1052 of file class.WordLevelDiff.php.

References $end, $n, array, and USE_ASSERTS.

                                               : 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);
 
         //wfProfileOut( $fname );
         return array($this->lcs, $seps);
     }
 
     public function _lcs_pos($ypos)
     {
         $fname = '_DiffEngine::_lcs_pos';
         //wfProfileIn( $fname );
 
         $end = $this->lcs;
         if ($end == 0 || $ypos > $this->seq[$end]) {
             $this->seq[++$this->lcs] = $ypos;
             $this->in_seq[$ypos] = 1;
             //wfProfileOut( $fname );
             return $this->lcs;
         }
 
         $beg = 1;
         while ($beg < $end) {
             $mid = (int) (($beg + $end) / 2);
             if ($ypos > $this->seq[$mid]) {

◆ _line_hash()

_DiffEngine::_line_hash ( $line )

Returns the whole line if it's small enough, or the MD5 hash otherwise.

Definition at line 940 of file class.WordLevelDiff.php.

                                {
                 $edits[] = new _DiffOp_Delete($delete);
             } elseif ($add) {
                 $edits[] = new _DiffOp_Add($add);
             }
         }
         //wfProfileOut( $fname );

◆ _shift_boundaries()

_DiffEngine::_shift_boundaries	(		$lines,
		&	$changed,
			$other_changed
	)

Definition at line 1158 of file class.WordLevelDiff.php.

References $changed, $i, and USE_ASSERTS.

     {
         $fname = '_DiffEngine::_shift_boundaries';
         //wfProfileIn( $fname );
         $i = 0;
         $j = 0;
 
         USE_ASSERTS && assert('sizeof($lines) == sizeof($changed)');
         $len = sizeof($lines);
         $other_len = sizeof($other_changed);
 
         while (1) {
             /*
              * Scan forwards to find 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[$i]) {
                 USE_ASSERTS && assert('$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]) {
                         $start--;
                     }
                     USE_ASSERTS && assert('$j > 0');
                     while ($other_changed[--$j]) {
                         continue;
                     }
                     USE_ASSERTS && 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++;
                     }
 
                     USE_ASSERTS && 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

◆ diff()

_DiffEngine::diff	(	$from_lines,
		$to_lines
	)

Definition at line 834 of file class.WordLevelDiff.php.

 {
     const MAX_XREF_LENGTH =  10000;
 
     public function diff($from_lines, $to_lines)
     {
         $fname = '_DiffEngine::diff';
         //wfProfileIn( $fname );
 
         $n_from = sizeof($from_lines);
         $n_to = sizeof($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++) {
             $xhash[$this->_line_hash($from_lines[$xi])] = 1;
         }
 
         for ($yi = $skip; $yi < $n_to - $endskip; $yi++) {
             $line = $to_lines[$yi];
             if (($this->ychanged[$yi] = empty($xhash[$this->_line_hash($line)]))) {
                 continue;
             }
             $yhash[$this->_line_hash($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($yhash[$this->_line_hash($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
         $this->_shift_boundaries($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 < $n_to) {
             USE_ASSERTS && assert($yi < $n_to || $this->xchanged[$xi]);
             USE_ASSERTS && 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) {
                 $edits[] = new _DiffOp_Copy($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]) {

Field Documentation

◆ MAX_XREF_LENGTH

const _DiffEngine::MAX_XREF_LENGTH = 10000

Definition at line 832 of file class.WordLevelDiff.php.

The documentation for this class was generated from the following file:

Services/COPage/mediawikidiff/class.WordLevelDiff.php

Public Member Functions

Data Fields