fix phpdoc comment
[lhc/web/wiklou.git] / includes / DifferenceEngine.php
index c5ade6e..7d910aa 100644 (file)
@@ -5,9 +5,14 @@
  * @subpackage DifferenceEngine
  */
 
+/** */
+require_once( 'Revision.php' );
+
 /**
  * @todo document
  * @access public
+ * @package MediaWiki 
+ * @subpackage DifferenceEngine
  */
 class DifferenceEngine {
        /* private */ var $mOldid, $mNewid;
@@ -215,7 +220,7 @@ class DifferenceEngine {
        }
        
        function getDiff( $otext, $ntext, $otitle, $ntitle ) {
-               global $wgUseExternalDiffEngine;
+               global $wgUseExternalDiffEngine, $wgContLang;
                $out = "
                        <table border='0' width='98%' cellpadding='0' cellspacing='4' class='diff'>
                        <tr>
@@ -223,7 +228,9 @@ class DifferenceEngine {
                                <td colspan='2' width='50%' align='center' class='diff-ntitle'>{$ntitle}</td>
                        </tr>
                ";
-
+               $otext = $wgContLang->segmentForDiff($otext);
+               $ntext = $wgContLang->segmentForDiff($ntext);
+               $difftext='';
                if ( $wgUseExternalDiffEngine ) {
                        # For historical reasons, external diff engine expects
                        # input text to be HTML-escaped already
@@ -232,15 +239,16 @@ class DifferenceEngine {
                        if( !function_exists( 'wikidiff_do_diff' ) ) {
                                dl('php_wikidiff.so');
                        }
-                       $out .= wikidiff_do_diff( $otext, $ntext, 2 );
+                       $difftext = wikidiff_do_diff( $otext, $ntext, 2 );
                } else {
                        $ota = explode( "\n", str_replace( "\r\n", "\n", $otext ) );
                        $nta = explode( "\n", str_replace( "\r\n", "\n", $ntext ) );
                        $diffs =& new Diff( $ota, $nta );
                        $formatter =& new TableDiffFormatter();
-                       $out .= $formatter->format( $diffs );
+                       $difftext = $formatter->format( $diffs );
                }
-               $out .= "</table>\n";
+               $difftext = $wgContLang->unsegmentForDiff($difftext);
+               $out .= $difftext."</table>\n";
                return $out;
        }
 
@@ -255,74 +263,45 @@ class DifferenceEngine {
                $fname = 'DifferenceEngine::loadText';
 
                $dbr =& wfGetDB( DB_SLAVE );
-               if ( 0 == $this->mNewid || 0 == $this->mOldid ) {
-                       $wgOut->setArticleFlag( true );
-                       $newLink = $wgTitle->escapeLocalUrl();
+               if( $this->mNewid ) {
+                       $this->newRev =& Revision::newFromId( $this->mNewid );
+               } else {
+                       $this->newRev =& Revision::newFromTitle( $wgTitle );
+               }
+               
+               if( $this->newRev->isCurrent() ) {
                        $this->mPagetitle = htmlspecialchars( wfMsg( 'currentrev' ) );
+                       $this->mNewPage = $wgTitle;
+                       $newLink = $this->mNewPage->escapeLocalUrl();
                        $this->mNewtitle = "<a href='$newLink'>{$this->mPagetitle}</a>";
-                       $id = $wgTitle->getArticleID();
-
-                       $s = $dbr->selectRow( 'cur', array( 'cur_text', 'cur_user_text', 'cur_comment' ),
-                               array( 'cur_id' => $id ), $fname );
-                       if ( $s === false ) {
-                               wfDebug( "Unable to load cur_id $id\n" );
-                               return false;
-                       }
-
-                       $this->mNewPage = &$wgTitle;
-                       $this->mNewtext = $s->cur_text;
-                       $this->mNewUser = $s->cur_user_text;
-                       $this->mNewComment = $s->cur_comment;
                } else {
-                       $s = $dbr->selectRow( 'old', array( 'old_namespace','old_title','old_timestamp', 'old_text',
-                               'old_flags','old_user_text','old_comment' ), array( 'old_id' => $this->mNewid ), $fname );
-
-                       if ( $s === false ) {
-                               wfDebug( "Unable to load old_id {$this->mNewid}\n" );
-                               return false;
-                       }
-
-                       $this->mNewtext = Article::getRevisionText( $s );
-
-                       $t = $wgLang->timeanddate( $s->old_timestamp, true );
-                       $this->mNewPage = Title::MakeTitle( $s->old_namespace, $s->old_title );
-                       $newLink = $wgTitle->escapeLocalUrl ('oldid=' . $this->mNewid);
+                       $this->mNewPage = $this->newRev->getTitle();
+                       $newLink = $this->mNewPage->escapeLocalUrl ('oldid=' . $this->mNewid );
+                       $t = $wgLang->timeanddate( $this->newRev->getTimestamp(), true );
                        $this->mPagetitle = htmlspecialchars( wfMsg( 'revisionasof', $t ) );
                        $this->mNewtitle = "<a href='$newLink'>{$this->mPagetitle}</a>";
-                       $this->mNewUser = $s->old_user_text;
-                       $this->mNewComment = $s->old_comment;
                }
-               if ( 0 == $this->mOldid ) {
-                       $s = $dbr->selectRow( 'old',
-                               array( 'old_namespace','old_title','old_timestamp','old_text', 'old_flags','old_user_text','old_comment' ),
-                               array( /* WHERE */
-                                       'old_namespace' => $this->mNewPage->getNamespace(),
-                                       'old_title' => $this->mNewPage->getDBkey()
-                               ), $fname, array( 'ORDER BY' => 'inverse_timestamp', 'USE INDEX' => 'name_title_timestamp' )
-                       );
-                       if ( $s === false ) {
-                               wfDebug( 'Unable to load ' . $this->mNewPage->getPrefixedDBkey() . " from old\n" );
-                               return false;
-                       }
+               
+               if( $this->mOldid ) {
+                       $this->oldRev =& Revision::newFromId( $this->mOldid );
                } else {
-                       $s = $dbr->selectRow( 'old',
-                               array( 'old_namespace','old_title','old_timestamp','old_text','old_flags','old_user_text','old_comment'),
-                               array( 'old_id' => $this->mOldid ),
-                               $fname
-                       );
-                       if ( $s === false ) {
-                               wfDebug( "Unable to load old_id {$this->mOldid}\n" );
-                               return false;
-                       }
+                       $this->oldRev =& $this->newRev->getPrevious();
+                       $this->mOldid = $this->oldRev->getId();
                }
-               $this->mOldPage = Title::MakeTitle( $s->old_namespace, $s->old_title );
-               $this->mOldtext = Article::getRevisionText( $s );
+                       
+               $this->mOldPage = $this->oldRev->getTitle();
 
-               $t = $wgLang->timeanddate( $s->old_timestamp, true );
-               $oldLink = $this->mOldPage->escapeLocalUrl ('oldid=' . $this->mOldid);
+               $t = $wgLang->timeanddate( $this->oldRev->getTimestamp(), true );
+               $oldLink = $this->mOldPage->escapeLocalUrl( 'oldid=' . $this->mOldid );
                $this->mOldtitle = "<a href='$oldLink'>" . htmlspecialchars( wfMsg( 'revisionasof', $t ) ) . '</a>';
-               $this->mOldUser = $s->old_user_text;
-               $this->mOldComment = $s->old_comment;
+               
+               $this->mNewUser = $this->newRev->getUserText();
+               $this->mNewComment = $this->newRev->getComment();
+               $this->mNewtext = $this->newRev->getText();
+               
+               $this->mOldUser = $this->oldRev->getUserText();
+               $this->mOldComment = $this->oldRev->getComment();
+               $this->mOldtext = $this->oldRev->getText();
 
                return true;
        }
@@ -339,6 +318,8 @@ define('USE_ASSERTS', function_exists('assert'));
 /**
  * @todo document
  * @access private
+ * @package MediaWiki 
+ * @subpackage DifferenceEngine
  */
 class _DiffOp {
        var $type;
@@ -361,6 +342,8 @@ class _DiffOp {
 /**
  * @todo document
  * @access private
+ * @package MediaWiki 
+ * @subpackage DifferenceEngine
  */
 class _DiffOp_Copy extends _DiffOp {
        var $type = 'copy';
@@ -380,6 +363,8 @@ class _DiffOp_Copy extends _DiffOp {
 /**
  * @todo document
  * @access private
+ * @package MediaWiki 
+ * @subpackage DifferenceEngine
  */
 class _DiffOp_Delete extends _DiffOp {
        var $type = 'delete';
@@ -397,6 +382,8 @@ class _DiffOp_Delete extends _DiffOp {
 /**
  * @todo document
  * @access private
+ * @package MediaWiki 
+ * @subpackage DifferenceEngine
  */
 class _DiffOp_Add extends _DiffOp {
        var $type = 'add';
@@ -414,6 +401,8 @@ class _DiffOp_Add extends _DiffOp {
 /**
  * @todo document
  * @access private
+ * @package MediaWiki 
+ * @subpackage DifferenceEngine
  */
 class _DiffOp_Change extends _DiffOp {
        var $type = 'change';
@@ -448,10 +437,15 @@ class _DiffOp_Change extends _DiffOp {
  *
  * @author Geoffrey T. Dairiki
  * @access private
+ * @package MediaWiki 
+ * @subpackage DifferenceEngine
  */
 class _DiffEngine
 {
        function diff ($from_lines, $to_lines) {
+               $fname = '_DiffEngine::diff';
+               wfProfileIn( $fname );
+               
                $n_from = sizeof($from_lines);
                $n_to = sizeof($to_lines);
 
@@ -535,6 +529,7 @@ class _DiffEngine
                        elseif ($add)
                                $edits[] = new _DiffOp_Add($add);
                }
+               wfProfileOut( $fname );
                return $edits;
        }
 
@@ -556,102 +551,111 @@ class _DiffEngine
         * 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 in X.
-                       $flip = true;
-               list ($xoff, $xlim, $yoff, $ylim)
-               = array( $yoff, $ylim, $xoff, $xlim);
+               $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; $chunk++) {
-               if ($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; $x++) {
+               if ($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];
+                                       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;
+                               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;
                                        }
-                       else if (empty($this->in_seq[$y])) {
-                       $k = $this->_lcs_pos($y);
-                       USE_ASSERTS && assert($k > 0);
-                       $ymids[$k] = $ymids[$k-1];
+                               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;
+                                       } else if (empty($this->in_seq[$y])) {
+                                               $k = $this->_lcs_pos($y);
+                                               USE_ASSERTS && assert($k > 0);
+                                               $ymids[$k] = $ymids[$k-1];
                                        }
                                }
                        }
+                       wfProfileOut( "$fname-chunk" );
                }
-
-       $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[] = $flip ? array($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);
+               $seps[] = $flip ? array($ylim, $xlim) : array($xlim, $ylim);
+       
+               wfProfileOut( $fname );
+               return array($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;
+               $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] )
-               $beg = $mid + 1;
-               else
-               $end = $mid;
+               $beg = 1;
+               while ($beg < $end) {
+                       $mid = (int)(($beg + $end) / 2);
+                       if ( $ypos > $this->seq[$mid] )
+                               $beg = $mid + 1;
+                       else
+                               $end = $mid;
                }
-
-       USE_ASSERTS && assert($ypos != $this->seq[$end]);
-
-       $this->in_seq[$this->seq[$end]] = false;
-       $this->seq[$end] = $ypos;
-       $this->in_seq[$ypos] = 1;
-       return $end;
+       
+               USE_ASSERTS && assert($ypos != $this->seq[$end]);
+       
+               $this->in_seq[$this->seq[$end]] = false;
+               $this->seq[$end] = $ypos;
+               $this->in_seq[$ypos] = 1;
+               wfProfileOut( $fname );
+               return $end;
        }
 
        /* Find LCS of two sequences.
@@ -666,48 +670,51 @@ class _DiffEngine
         * 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
+               $fname = '_DiffEngine::_compareseq';
+               wfProfileIn( $fname );
+               
+               // Slide down the bottom initial diagonal.
+               while ($xoff < $xlim && $yoff < $ylim
                           && $this->xv[$xoff] == $this->yv[$yoff]) {
-               ++$xoff;
-               ++$yoff;
+                       ++$xoff;
+                       ++$yoff;
                }
 
-       // Slide up the top initial diagonal.
-       while ($xlim > $xoff && $ylim > $yoff
+               // Slide up the top initial diagonal.
+               while ($xlim > $xoff && $ylim > $yoff
                           && $this->xv[$xlim - 1] == $this->yv[$ylim - 1]) {
-               --$xlim;
-               --$ylim;
+                       --$xlim;
+                       --$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 ($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 = $pt2;
+               if ($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;
                        }
                }
+               wfProfileOut( $fname );
        }
 
        /* Adjust inserts/deletes of identical lines to join changes
@@ -723,110 +730,113 @@ class _DiffEngine
         * This is extracted verbatim from analyze.c (GNU diffutils-2.7).
         */
        function _shift_boundaries ($lines, &$changed, $other_changed) {
-       $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;
+               $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 - $start);
-
-               /*
-                * If possible, move the fully-merged run of changes
-                * back to a corresponding run in the other file.
-                */
-               while ($corresponding < $i) {
-               $changed[--$start] = 1;
-               $changed[--$i] = 0;
-               USE_ASSERTS && assert('$j > 0');
-               while ($other_changed[--$j])
-                       continue;
-               USE_ASSERTS && assert('$j >= 0 && !$other_changed[$j]');
+       
+                       /*
+                        * 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;
+                               USE_ASSERTS && assert('$j > 0');
+                               while ($other_changed[--$j])
+                                       continue;
+                               USE_ASSERTS && assert('$j >= 0 && !$other_changed[$j]');
                        }
                }
+               wfProfileOut( $fname );
        }
 }
 
@@ -834,6 +844,8 @@ class _DiffEngine
  * Class representing a 'diff' between two sequences of strings.
  * @todo document
  * @access private
+ * @package MediaWiki 
+ * @subpackage DifferenceEngine
  */
 class Diff
 {
@@ -864,12 +876,12 @@ class Diff
         *                                original diff.
         */
        function reverse () {
-       $rev = $this;
+               $rev = $this;
                $rev->edits = array();
                foreach ($this->edits as $edit) {
                        $rev->edits[] = $edit->reverse();
                }
-       return $rev;
+               return $rev;
        }
 
        /**
@@ -893,12 +905,12 @@ class Diff
         * @return int The length of the LCS.
         */
        function lcs () {
-       $lcs = 0;
+               $lcs = 0;
                foreach ($this->edits as $edit) {
                        if ($edit->type == 'copy')
                                $lcs += sizeof($edit->orig);
                }
-       return $lcs;
+               return $lcs;
        }
 
        /**
@@ -943,6 +955,8 @@ class Diff
         * This is here only for debugging purposes.
         */
        function _check ($from_lines, $to_lines) {
+               $fname = 'Diff::_check';
+               wfProfileIn( $fname );
                if (serialize($from_lines) != serialize($this->orig()))
                        trigger_error("Reconstructed original doesn't match", E_USER_ERROR);
                if (serialize($to_lines) != serialize($this->closing()))
@@ -964,6 +978,7 @@ class Diff
 
                $lcs = $this->lcs();
                trigger_error('Diff okay: LCS = '.$lcs, E_USER_NOTICE);
+               wfProfileOut( $fname );
        }
 }
 
@@ -971,6 +986,8 @@ class Diff
  * FIXME: bad name.
  * @todo document
  * @access private
+ * @package MediaWiki 
+ * @subpackage DifferenceEngine
  */
 class MappedDiff extends Diff
 {
@@ -999,7 +1016,9 @@ class MappedDiff extends Diff
         */
        function MappedDiff($from_lines, $to_lines,
                                                $mapped_from_lines, $mapped_to_lines) {
-
+               $fname = 'MappedDiff::MappedDiff';
+               wfProfileIn( $fname );
+               
                assert(sizeof($from_lines) == sizeof($mapped_from_lines));
                assert(sizeof($to_lines) == sizeof($mapped_to_lines));
 
@@ -1019,6 +1038,7 @@ class MappedDiff extends Diff
                                $yi += sizeof($closing);
                        }
                }
+               wfProfileOut( $fname );
        }
 }
 
@@ -1030,6 +1050,8 @@ class MappedDiff extends Diff
  * to obtain fancier outputs.
  * @todo document
  * @access private
+ * @package MediaWiki 
+ * @subpackage DifferenceEngine
  */
 class DiffFormatter
 {
@@ -1056,6 +1078,8 @@ class DiffFormatter
         * @return string The formatted output.
         */
        function format($diff) {
+               $fname = 'DiffFormatter::format';
+               wfProfileIn( $fname );
 
                $xi = $yi = 1;
                $block = false;
@@ -1108,10 +1132,14 @@ class DiffFormatter
                                                  $y0, $yi - $y0,
                                                  $block);
 
-               return $this->_end_diff();
+               $end = $this->_end_diff();
+               wfProfileOut( $fname );
+               return $end;
        }
 
        function _block($xbeg, $xlen, $ybeg, $ylen, &$edits) {
+               $fname = 'DiffFormatter::_block';
+               wfProfileIn( $fname );
                $this->_start_block($this->_block_header($xbeg, $xlen, $ybeg, $ylen));
                foreach ($edits as $edit) {
                        if ($edit->type == 'copy')
@@ -1126,6 +1154,7 @@ class DiffFormatter
                                trigger_error('Unknown edit type', E_USER_ERROR);
                }
                $this->_end_block();
+               wfProfileOut( $fname );
        }
 
        function _start_diff() {
@@ -1188,6 +1217,8 @@ define('NBSP', '&#160;');                 // iso-8859-x non-breaking space.
 /**
  * @todo document
  * @access private
+ * @package MediaWiki 
+ * @subpackage DifferenceEngine
  */
 class _HWLDF_WordAccumulator {
        function _HWLDF_WordAccumulator () {
@@ -1245,28 +1276,40 @@ class _HWLDF_WordAccumulator {
 /**
  * @todo document
  * @access private
+ * @package MediaWiki 
+ * @subpackage DifferenceEngine
  */
 class WordLevelDiff extends MappedDiff
 {
        function WordLevelDiff ($orig_lines, $closing_lines) {
+               $fname = 'WordLevelDiff::WordLevelDiff';
+               wfProfileIn( $fname );
+               
                list ($orig_words, $orig_stripped) = $this->_split($orig_lines);
                list ($closing_words, $closing_stripped) = $this->_split($closing_lines);
 
 
                $this->MappedDiff($orig_words, $closing_words,
                                                  $orig_stripped, $closing_stripped);
+               wfProfileOut( $fname );
        }
 
        function _split($lines) {
+               $fname = 'WordLevelDiff::_split';
+               wfProfileIn( $fname );
                if (!preg_match_all('/ ( [^\S\n]+ | [0-9_A-Za-z\x80-\xff]+ | . ) (?: (?!< \n) [^\S\n])? /xs',
                                                        implode("\n", $lines),
                                                        $m)) {
+                       wfProfileOut( $fname );
                        return array(array(''), array(''));
                }
+               wfProfileOut( $fname );
                return array($m[0], $m[1]);
        }
 
        function orig () {
+               $fname = 'WordLevelDiff::orig';
+               wfProfileIn( $fname );
                $orig = new _HWLDF_WordAccumulator;
 
                foreach ($this->edits as $edit) {
@@ -1275,10 +1318,14 @@ class WordLevelDiff extends MappedDiff
                        elseif ($edit->orig)
                                $orig->addWords($edit->orig, 'mark');
                }
-               return $orig->getLines();
+               $lines = $orig->getLines();
+               wfProfileOut( $fname );
+               return $lines;
        }
 
        function closing () {
+               $fname = 'WordLevelDiff::closing';
+               wfProfileIn( $fname );
                $closing = new _HWLDF_WordAccumulator;
 
                foreach ($this->edits as $edit) {
@@ -1287,7 +1334,9 @@ class WordLevelDiff extends MappedDiff
                        elseif ($edit->closing)
                                $closing->addWords($edit->closing, 'mark');
                }
-               return $closing->getLines();
+               $lines = $closing->getLines();
+               wfProfileOut( $fname );
+               return $lines;
        }
 }
 
@@ -1295,6 +1344,8 @@ class WordLevelDiff extends MappedDiff
  *     Wikipedia Table style diff formatter.
  * @todo document
  * @access private
+ * @package MediaWiki 
+ * @subpackage DifferenceEngine
  */
 class TableDiffFormatter extends DiffFormatter
 {
@@ -1365,6 +1416,9 @@ class TableDiffFormatter extends DiffFormatter
        }
 
        function _changed( $orig, $closing ) {
+               $fname = 'TableDiffFormatter::_changed';
+               wfProfileIn( $fname );
+               
                $diff = new WordLevelDiff( $orig, $closing );
                $del = $diff->orig();
                $add = $diff->closing();
@@ -1381,6 +1435,7 @@ class TableDiffFormatter extends DiffFormatter
                        echo '<tr>' . $this->emptyLine() .
                                $this->addedLine( $line ) . "</tr>\n";
                }
+               wfProfileOut( $fname );
        }
 }