* Add support for a version key in $wgExtensionCredits
[lhc/web/wiklou.git] / includes / DifferenceEngine.php
index 3bc8269..24d0767 100644 (file)
@@ -1,40 +1,55 @@
 <?php
-# See diff.doc
+/**
+ * See diff.doc
+ * @package MediaWiki 
+ * @subpackage DifferenceEngine
+ */
+
+/** */
+require_once( 'Revision.php' );
 
+/**
+ * @todo document
+ * @access public
+ * @package MediaWiki 
+ * @subpackage DifferenceEngine
+ */
 class DifferenceEngine {
-       /* private */ var $mOldid, $mNewid;
-       /* private */ var $mOldtitle, $mNewtitle, $mPagetitle;
-       /* private */ var $mOldtext, $mNewtext;
-       /* private */ var $mOldUser, $mNewUser;
-       /* private */ var $mOldComment, $mNewComment;
-       /* private */ var $mOldPage, $mNewPage;
-       /* private */ var $mRcidMarkPatrolled;
-
-       function DifferenceEngine( $old, $new, $rcid = 0 )
-       {
+       /**#@+
+        * @access private
+        */
+       var $mOldid, $mNewid;
+       var $mOldtitle, $mNewtitle, $mPagetitle;
+       var $mOldtext, $mNewtext;
+       var $mOldUser, $mNewUser;
+       var $mOldComment, $mNewComment;
+       var $mOldPage, $mNewPage;
+       var $mRcidMarkPatrolled;
+       /**#@-*/
+
+       /**
+        * Constructor
+        * @param integer $old Old ID we want to show and diff with.
+        * @param string $new Either 'prev' or 'next'. 
+        * @param integer $rcid ??? (default 0)
+        */
+       function DifferenceEngine( $old, $new, $rcid = 0 ) {
                global $wgTitle;
+
                if ( 'prev' == $new ) {
                        # Show diff between revision $old and the previous one.
                        # Get previous one from DB.
                        #
                        $this->mNewid = intval($old);
-                       $dbr =& wfGetDB( DB_SLAVE );
-                       $this->mOldid = $dbr->selectField( 'old', 'old_id',  
-                               "old_title='" . $wgTitle->getDBkey() . "'" .
-                               ' AND old_namespace=' . $wgTitle->getNamespace() .
-                               " AND old_id<{$this->mNewid} ORDER BY old_id DESC" );
 
-               } elseif ( 'next' == $new ) {
+                       $this->mOldid = $wgTitle->getPreviousRevisionID( $this->mNewid );
 
+               } elseif ( 'next' == $new ) {
                        # Show diff between revision $old and the previous one.
                        # Get previous one from DB.
                        #
                        $this->mOldid = intval($old);
-                       $dbr =& wfGetDB( DB_SLAVE );
-                       $this->mNewid = $dbr->selectField( 'old', 'old_id',  
-                               "old_title='" . $wgTitle->getDBkey() . "'" .
-                               ' AND old_namespace=' . $wgTitle->getNamespace() .
-                               " AND old_id>{$this->mOldid} ORDER BY old_id " );
+                       $this->mNewid = $wgTitle->getNextRevisionID( $this->mOldid );
                        if ( false === $this->mNewid ) {
                                # if no result, NewId points to the newest old revision. The only newer
                                # revision is cur, which is "0".
@@ -42,18 +57,46 @@ class DifferenceEngine {
                        }
 
                } else {
-
                        $this->mOldid = intval($old);
                        $this->mNewid = intval($new);
                }
                $this->mRcidMarkPatrolled = intval($rcid);  # force it to be an integer
        }
 
-       function showDiffPage()
-       {
-               global $wgUser, $wgTitle, $wgOut, $wgLang, $wgOnlySysopsCanPatrol, $wgUseRCPatrol;
+       function showDiffPage() {
+               global $wgUser, $wgTitle, $wgOut, $wgContLang, $wgOnlySysopsCanPatrol,
+                      $wgUseExternalEditor, $wgUseRCPatrol;
                $fname = 'DifferenceEngine::showDiffPage';
                wfProfileIn( $fname );
+                               
+               # If external diffs are enabled both globally and for the user,
+               # we'll use the application/x-external-editor interface to call
+               # an external diff tool like kompare, kdiff3, etc.
+               if($wgUseExternalEditor && $wgUser->getOption('externaldiff')) {
+                       global $wgInputEncoding,$wgServer,$wgScript,$wgLang;
+                       $wgOut->disable();
+                       header ( "Content-type: application/x-external-editor; charset=".$wgInputEncoding );
+                       $url1=$wgTitle->getFullURL("action=raw&oldid=".$this->mOldid);                  
+                       $url2=$wgTitle->getFullURL("action=raw&oldid=".$this->mNewid);
+                       $special=$wgLang->getNsText(NS_SPECIAL);
+                       $control=<<<CONTROL
+[Process]
+Type=Diff text
+Engine=MediaWiki
+Script={$wgServer}{$wgScript}
+Special namespace={$special}
+
+[File]
+Extension=wiki
+URL=$url1
+
+[File 2]
+Extension=wiki
+URL=$url2
+CONTROL;
+                       echo($control);
+                       return;
+               }
 
                # mOldid is false if the difference engine is called with a "vague" query for
                # a diff between a version V and its previous version V' AND the version V
@@ -95,7 +138,7 @@ class DifferenceEngine {
                }
 
                $sk = $wgUser->getSkin();
-               $talk = $wgLang->getNsText( NS_TALK );
+               $talk = $wgContLang->getNsText( NS_TALK );
                $contribs = wfMsg( 'contribslink' );
 
                $this->mOldComment = $sk->formatComment($this->mOldComment);
@@ -109,14 +152,16 @@ class DifferenceEngine {
                        'target=' . urlencode($this->mOldUser) );
                $newContribs = $sk->makeKnownLinkObj( Title::makeTitle( NS_SPECIAL, 'Contributions' ), $contribs,
                        'target=' . urlencode($this->mNewUser) );
-               if ( !$this->mNewid && $wgUser->isSysop() ) {
+               if ( $this->newRev->isCurrent() && $wgUser->isAllowed('rollback') ) {
                        $rollback = '&nbsp;&nbsp;&nbsp;<strong>[' . $sk->makeKnownLinkObj( $wgTitle, wfMsg( 'rollbacklink' ),
-                               'action=rollback&from=' . urlencode($this->mNewUser) ) . ']</strong>';
+                               'action=rollback&from=' . urlencode($this->mNewUser) .
+                               '&token=' . urlencode( $wgUser->editToken( array( $wgTitle->getPrefixedText(), $this->mNewUser ) ) ) ) .
+                               ']</strong>';
                } else {
                        $rollback = '';
                }
-               if ( $wgUseRCPatrol && $this->mRcidMarkPatrolled != 0 && $wgUser->getID() != 0 &&
-                    ( $wgUser->isSysop() || !$wgOnlySysopsCanPatrol ) )
+               if ( $wgUseRCPatrol && $this->mRcidMarkPatrolled != 0 && $wgUser->isLoggedIn() &&
+                    ( $wgUser->isAllowed('rollback') || !$wgOnlySysopsCanPatrol ) )
                {
                        $patrol = ' [' . $sk->makeKnownLinkObj( $wgTitle, wfMsg( 'markaspatrolleddiff' ),
                                "action=markpatrolled&rcid={$this->mRcidMarkPatrolled}" ) . ']';
@@ -125,7 +170,7 @@ class DifferenceEngine {
                }
 
                $prevlink = $sk->makeKnownLinkObj( $wgTitle, wfMsg( 'previousdiff' ), 'diff=prev&oldid='.$this->mOldid );
-               if ( $this->mNewid == 0 ) {
+               if ( $this->newRev->isCurrent() ) {
                        $nextlink = '';
                } else {
                        $nextlink = $sk->makeKnownLinkObj( $wgTitle, wfMsg( 'nextdiff' ), 'diff=next&oldid='.$this->mNewid );
@@ -135,22 +180,29 @@ class DifferenceEngine {
                        "($oldUTLink | $oldContribs)<br />" . $this->mOldComment .
                        '<br />' . $prevlink;
                $newHeader = "<strong>{$this->mNewtitle}</strong><br />$newUserLink " .
-                       "($newUTLink | $newContribs) $rollback<br />" . $this->mNewComment . 
+                       "($newUTLink | $newContribs) $rollback<br />" . $this->mNewComment .
                        '<br />' . $nextlink . $patrol;
 
                DifferenceEngine::showDiff( $this->mOldtext, $this->mNewtext,
                  $oldHeader, $newHeader );
                $wgOut->addHTML( "<hr /><h2>{$this->mPagetitle}</h2>\n" );
+
+               if( !$this->newRev->isCurrent() ) {
+                       $oldEditSectionSetting = $wgOut->mParserOptions->setEditSection( false );
+               }
                $wgOut->addWikiText( $this->mNewtext );
+               if( !$this->newRev->isCurrent() ) {
+                       $wgOut->mParserOptions->setEditSection( $oldEditSectionSetting );
+               }
 
                wfProfileOut( $fname );
        }
 
-       # Show the first revision of an article. Uses normal diff headers in contrast to normal
-       # "old revision" display style.
-       #
-       function showFirstRevision()
-       {
+       /**
+        * Show the first revision of an article. Uses normal diff headers in
+        * contrast to normal "old revision" display style.
+        */
+       function showFirstRevision() {
                global $wgOut, $wgTitle, $wgUser, $wgLang;
 
                $fname = 'DifferenceEngine::showFirstRevision';
@@ -192,7 +244,7 @@ class DifferenceEngine {
                $header = "<div class=\"firstrevisionheader\" style=\"text-align: center\"><strong>{$this->mOldtitle}</strong><br />$userLink " .
                        "($uTLink | $contribs)<br />" . $this->mOldComment .
                        '<br />' . $nextlink. "</div>\n";
-       
+
                $wgOut->addHTML( $header );
 
                $wgOut->setSubtitle( wfMsg( 'difference' ) );
@@ -207,106 +259,101 @@ class DifferenceEngine {
                wfProfileOut( $fname );
        }
 
-       function showDiff( $otext, $ntext, $otitle, $ntitle )
-       {
-               global $wgOut, $wgUseExternalDiffEngine;
-
-               $otext = str_replace( "\r\n", "\n", $otext );
-               $ntext = str_replace( "\r\n", "\n", $ntext );
-
-
-                       $wgOut->addHTML( "<table border='0' width='98%'
-cellpadding='0' cellspacing='4px' class='diff'><tr>
-<td colspan='2' width='50%' align='center' class='diff-otitle'>
-{$otitle}</td>
-<td colspan='2' width='50%' align='center' class='diff-ntitle'>
-{$ntitle}</td>
-</tr>\n" );
+       function showDiff( $otext, $ntext, $otitle, $ntitle ) {
+               global $wgOut;
+               $wgOut->addHTML( DifferenceEngine::getDiff( $otext, $ntext, $otitle, $ntitle ) );
+       }
+       
+       function getDiff( $otext, $ntext, $otitle, $ntitle ) {
+               global $wgUseExternalDiffEngine, $wgContLang;
+               $out = "
+                       <table border='0' width='98%' cellpadding='0' cellspacing='4' class='diff'>
+                       <tr>
+                               <td colspan='2' width='50%' align='center' class='diff-otitle'>{$otitle}</td>
+                               <td colspan='2' width='50%' align='center' class='diff-ntitle'>{$ntitle}</td>
+                       </tr>
+               ";
+               $otext = $wgContLang->segmentForDiff($otext);
+               $ntext = $wgContLang->segmentForDiff($ntext);
+               $difftext='';
                if ( $wgUseExternalDiffEngine ) {
-                       dl('php_wikidiff.so');
-                       $wgOut->addHTML( wikidiff_do_diff( $otext, $ntext, 2) );
+                       # For historical reasons, external diff engine expects
+                       # input text to be HTML-escaped already
+                       $otext = str_replace( "\r\n", "\n", htmlspecialchars ( $otext ) );
+                       $ntext = str_replace( "\r\n", "\n", htmlspecialchars ( $ntext ) );
+                       if( !function_exists( 'wikidiff_do_diff' ) ) {
+                               dl('php_wikidiff.so');
+                       }
+                       $difftext = wikidiff_do_diff( $otext, $ntext, 2 );
                } else {
-                       $ota = explode( "\n", $otext);
-                       $nta = explode( "\n", $ntext);
-                       $diffs = new Diff( $ota, $nta );
-                       $formatter = new TableDiffFormatter();
-                       $formatter->format( $diffs );
+                       $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();
+                       $difftext = $formatter->format( $diffs );
                }
-               $wgOut->addHTML( "</table>\n" );
+               $difftext = $wgContLang->unsegmentForDiff($difftext);
+               $out .= $difftext."</table>\n";
+               return $out;
        }
 
-       # Load the text of the articles to compare.  If newid is 0, then compare
-       # the old article in oldid to the current article; if oldid is 0, then
-       # compare the current article to the immediately previous one (ignoring
-       # the value of newid).
-       #
-       function loadText()
-       {
+       /**
+        * Load the text of the articles to compare.  If newid is 0, then compare
+        * the old article in oldid to the current article; if oldid is 0, then
+        * compare the current article to the immediately previous one (ignoring the
+        * value of newid).
+        */     
+       function loadText() {
                global $wgTitle, $wgOut, $wgLang;
                $fname = 'DifferenceEngine::loadText';
 
                $dbr =& wfGetDB( DB_SLAVE );
-               if ( 0 == $this->mNewid || 0 == $this->mOldid ) {
+               if( $this->mNewid ) {
+                       $this->newRev =& Revision::newFromId( $this->mNewid );
+               } else {
+                       $this->newRev =& Revision::newFromTitle( $wgTitle );
+               }
+               if( is_null( $this->newRev ) ) {
+                       return false;
+               }
+               
+               if( $this->newRev->isCurrent() ) {
                        $wgOut->setArticleFlag( true );
-                       $newLink = $wgTitle->getLocalUrl();
-                       $this->mPagetitle = wfMsg( 'currentrev' );
+                       $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->getArray( 'cur', array( 'cur_text', 'cur_user_text', 'cur_comment' ),
-                               array( 'cur_id' => $id ), $fname );
-                       if ( $s === false ) {
-                               return false;
-                       }
-
-                       $this->mNewPage = &$wgTitle;
-                       $this->mNewtext = $s->cur_text;
-                       $this->mNewUser = $s->cur_user_text;
-                       $this->mNewComment = $s->cur_comment;
                } else {
-                       $s = $dbr->getArray( '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 ) {
-                               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->getLocalUrl ('oldid=' . $this->mNewid);
-                       $this->mPagetitle = wfMsg( 'revisionasof', $t );
+                       $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->getArray( '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( $this->mOldid ) {
+                       $this->oldRev =& Revision::newFromId( $this->mOldid );
                } else {
-                       $s = $dbr->getArray( 'old',
-                               array( 'old_namespace','old_title','old_timestamp','old_text','old_flags','old_user_text','old_comment'),
-                               array( 'old_id' => $this->mOldid ),
-                               $fname
-                       );
+                       $this->oldRev =& $this->newRev->getPrevious();
+                       $this->mOldid = $this->oldRev->getId();
                }
-               if ( $s === false ) {
+               if( is_null( $this->oldRev ) ) {
                        return false;
                }
-               $this->mOldPage = Title::MakeTitle( $s->old_namespace, $s->old_title );
-               $this->mOldtext = Article::getRevisionText( $s );
-
-               $t = $wgLang->timeanddate( $s->old_timestamp, true );
-               $oldLink = $this->mOldPage->getLocalUrl ('oldid=' . $this->mOldid);
-               $this->mOldtitle = "<a href='$oldLink'>" . wfMsg( 'revisionasof', $t ) . '</a>';
-               $this->mOldUser = $s->old_user_text;
-               $this->mOldComment = $s->old_comment;
+                       
+               $this->mOldPage = $this->oldRev->getTitle();
+
+               $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->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;
        }
@@ -320,6 +367,12 @@ cellpadding='0' cellspacing='4px' class='diff'><tr>
 
 define('USE_ASSERTS', function_exists('assert'));
 
+/**
+ * @todo document
+ * @access private
+ * @package MediaWiki 
+ * @subpackage DifferenceEngine
+ */
 class _DiffOp {
        var $type;
        var $orig;
@@ -338,6 +391,12 @@ class _DiffOp {
        }
 }
 
+/**
+ * @todo document
+ * @access private
+ * @package MediaWiki 
+ * @subpackage DifferenceEngine
+ */
 class _DiffOp_Copy extends _DiffOp {
        var $type = 'copy';
 
@@ -353,6 +412,12 @@ class _DiffOp_Copy extends _DiffOp {
        }
 }
 
+/**
+ * @todo document
+ * @access private
+ * @package MediaWiki 
+ * @subpackage DifferenceEngine
+ */
 class _DiffOp_Delete extends _DiffOp {
        var $type = 'delete';
 
@@ -366,6 +431,12 @@ class _DiffOp_Delete extends _DiffOp {
        }
 }
 
+/**
+ * @todo document
+ * @access private
+ * @package MediaWiki 
+ * @subpackage DifferenceEngine
+ */
 class _DiffOp_Add extends _DiffOp {
        var $type = 'add';
 
@@ -379,6 +450,12 @@ class _DiffOp_Add extends _DiffOp {
        }
 }
 
+/**
+ * @todo document
+ * @access private
+ * @package MediaWiki 
+ * @subpackage DifferenceEngine
+ */
 class _DiffOp_Change extends _DiffOp {
        var $type = 'change';
 
@@ -412,10 +489,15 @@ 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);
 
@@ -499,6 +581,7 @@ class _DiffEngine
                        elseif ($add)
                                $edits[] = new _DiffOp_Add($add);
                }
+               wfProfileOut( $fname );
                return $edits;
        }
 
@@ -520,102 +603,111 @@ 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 (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;
-                                       }
-                       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.
@@ -630,48 +722,51 @@ 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
@@ -687,115 +782,122 @@ 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 );
        }
 }
 
 /**
  * Class representing a 'diff' between two sequences of strings.
+ * @todo document
+ * @access private
+ * @package MediaWiki 
+ * @subpackage DifferenceEngine
  */
 class Diff
 {
@@ -826,12 +928,12 @@ 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;
        }
 
        /**
@@ -855,12 +957,12 @@ 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;
        }
 
        /**
@@ -905,6 +1007,8 @@ 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()))
@@ -926,14 +1030,18 @@ class Diff
 
                $lcs = $this->lcs();
                trigger_error('Diff okay: LCS = '.$lcs, E_USER_NOTICE);
+               wfProfileOut( $fname );
        }
 }
 
 /**
  * FIXME: bad name.
+ * @todo document
+ * @access private
+ * @package MediaWiki 
+ * @subpackage DifferenceEngine
  */
-class MappedDiff
-extends Diff
+class MappedDiff extends Diff
 {
        /**
         * Constructor.
@@ -960,7 +1068,9 @@ 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));
 
@@ -980,6 +1090,7 @@ extends Diff
                                $yi += sizeof($closing);
                        }
                }
+               wfProfileOut( $fname );
        }
 }
 
@@ -989,6 +1100,10 @@ extends Diff
  * This class formats the diff in classic diff format.
  * It is intended that this class be customized via inheritance,
  * to obtain fancier outputs.
+ * @todo document
+ * @access private
+ * @package MediaWiki 
+ * @subpackage DifferenceEngine
  */
 class DiffFormatter
 {
@@ -1015,6 +1130,8 @@ class DiffFormatter
         * @return string The formatted output.
         */
        function format($diff) {
+               $fname = 'DiffFormatter::format';
+               wfProfileIn( $fname );
 
                $xi = $yi = 1;
                $block = false;
@@ -1067,10 +1184,14 @@ 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')
@@ -1085,6 +1206,7 @@ class DiffFormatter
                                trigger_error('Unknown edit type', E_USER_ERROR);
                }
                $this->_end_block();
+               wfProfileOut( $fname );
        }
 
        function _start_diff() {
@@ -1144,6 +1266,12 @@ class DiffFormatter
 
 define('NBSP', '&#160;');                      // iso-8859-x non-breaking space.
 
+/**
+ * @todo document
+ * @access private
+ * @package MediaWiki 
+ * @subpackage DifferenceEngine
+ */
 class _HWLDF_WordAccumulator {
        function _HWLDF_WordAccumulator () {
                $this->_lines = array();
@@ -1155,7 +1283,8 @@ class _HWLDF_WordAccumulator {
        function _flushGroup ($new_tag) {
                if ($this->_group !== '') {
                        if ($this->_tag == 'mark')
-                               $this->_line .= '<span class="diffchange">'.htmlspecialchars ( $this->_group ).'</span>';
+                               $this->_line .= '<span class="diffchange">' .
+                                       htmlspecialchars ( $this->_group ) . '</span>';
                        else
                                $this->_line .= htmlspecialchars ( $this->_group );
                }
@@ -1168,6 +1297,7 @@ class _HWLDF_WordAccumulator {
                if ($this->_line != '')
                        array_push ( $this->_lines, $this->_line );
                else
+                       # make empty lines visible by inserting an NBSP
                        array_push ( $this->_lines, NBSP );
                $this->_line = '';
        }
@@ -1195,27 +1325,43 @@ 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 $edit) {
@@ -1224,10 +1370,14 @@ class WordLevelDiff extends MappedDiff
                        elseif ($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 $edit) {
@@ -1236,13 +1386,18 @@ class WordLevelDiff extends MappedDiff
                        elseif ($edit->closing)
                                $closing->addWords($edit->closing, 'mark');
                }
-               return $closing->getLines();
+               $lines = $closing->getLines();
+               wfProfileOut( $fname );
+               return $lines;
        }
 }
 
 /**
  *     Wikipedia Table style diff formatter.
- *
+ * @todo document
+ * @access private
+ * @package MediaWiki 
+ * @subpackage DifferenceEngine
  */
 class TableDiffFormatter extends DiffFormatter
 {
@@ -1256,13 +1411,13 @@ class TableDiffFormatter extends DiffFormatter
                $l2 = wfMsg( 'lineno', $ybeg );
 
                $r = '<tr><td colspan="2" align="left"><strong>'.$l1."</strong></td>\n" .
-                       '<td colspan="2" align="left"><strong>'.$l2."</strong></td></tr>\n";
+                 '<td colspan="2" align="left"><strong>'.$l2."</strong></td></tr>\n";
                return $r;
        }
 
        function _start_block( $header ) {
                global $wgOut;
-               $wgOut->addHTML( $header );
+               echo $header;
        }
 
        function _end_block() {
@@ -1271,61 +1426,68 @@ class TableDiffFormatter extends DiffFormatter
        function _lines( $lines, $prefix=' ', $color='white' ) {
        }
 
+       # HTML-escape parameter before calling this
        function addedLine( $line ) {
-               return '<td>+</td><td class="diff-addedline">' .
-                       $line . '</td>';
+               return "<td>+</td><td class='diff-addedline'>{$line}</td>";
        }
 
+       # HTML-escape parameter before calling this
        function deletedLine( $line ) {
-               return '<td>-</td><td class="diff-deletedline">' .
-                       $line . '</td>';
+               return "<td>-</td><td class='diff-deletedline'>{$line}</td>";
        }
 
-       function emptyLine() {
-               return '<td colspan="2">&nbsp;</td>';
+       # HTML-escape parameter before calling this
+       function contextLine( $line ) {
+               return "<td> </td><td class='diff-context'>{$line}</td>";
        }
 
-       function contextLine( $line ) {
-               return '<td> </td><td class="diff-context">' .
-                       htmlspecialchars ( $line ) . '</td>';
+       function emptyLine() {
+               return '<td colspan="2">&nbsp;</td>';
        }
 
-       function _added($lines) {
-               global $wgOut;
+       function _added( $lines ) {
                foreach ($lines as $line) {
-                       $wgOut->addHTML( '<tr>' . $this->emptyLine() .
-                         $this->addedLine( htmlspecialchars ( $line ) ) . "</tr>\n" );
+                       echo '<tr>' . $this->emptyLine() .
+                               $this->addedLine( htmlspecialchars ( $line ) ) . "</tr>\n";
                }
        }
 
        function _deleted($lines) {
-               global $wgOut;
                foreach ($lines as $line) {
-                       $wgOut->addHTML( '<tr>' . $this->deletedLine( htmlspecialchars ( $line ) ) .
-                         $this->emptyLine() . "</tr>\n" );
+                       echo '<tr>' . $this->deletedLine( htmlspecialchars ( $line ) ) .
+                         $this->emptyLine() . "</tr>\n";
                }
        }
 
        function _context( $lines ) {
-               global $wgOut;
                foreach ($lines as $line) {
-                       $wgOut->addHTML( '<tr>' . $this->contextLine( $line ) .
-                         $this->contextLine( $line ) . "</tr>\n" );
+                       echo '<tr>' .
+                               $this->contextLine( htmlspecialchars ( $line ) ) .
+                               $this->contextLine( htmlspecialchars ( $line ) ) . "</tr>\n";
                }
        }
 
        function _changed( $orig, $closing ) {
-               global $wgOut;
+               $fname = 'TableDiffFormatter::_changed';
+               wfProfileIn( $fname );
+               
                $diff = new WordLevelDiff( $orig, $closing );
                $del = $diff->orig();
                $add = $diff->closing();
 
+               # Notice that WordLevelDiff returns HTML-escaped output.
+               # Hence, we will be calling addedLine/deletedLine without HTML-escaping.
+
                while ( $line = array_shift( $del ) ) {
                        $aline = array_shift( $add );
-                       $wgOut->addHTML( '<tr>' . $this->deletedLine( $line ) .
-                         $this->addedLine( $aline ) . "</tr>\n" );
+                       echo '<tr>' . $this->deletedLine( $line ) .
+                               $this->addedLine( $aline ) . "</tr>\n";
                }
-               $this->_added( $add ); # If any leftovers
+               foreach ($add as $line) {       # If any leftovers
+                       echo '<tr>' . $this->emptyLine() .
+                               $this->addedLine( $line ) . "</tr>\n";
+               }
+               wfProfileOut( $fname );
        }
 }