Avoid undefined variable error on null edits
[lhc/web/wiklou.git] / includes / DifferenceEngine.php
index 66edfa9..77e9583 100644 (file)
@@ -8,6 +8,9 @@
 /** */
 require_once( 'Revision.php' );
 
+define( 'MAX_DIFF_LINE', 10000 );
+define( 'MAX_DIFF_XREF_LENGTH', 10000 );
+
 /**
  * @todo document
  * @access public
@@ -18,23 +21,27 @@ class DifferenceEngine {
        /**#@+
         * @access private
         */
-       var $mOldid, $mNewid;
+       var $mOldid, $mNewid, $mTitle;
        var $mOldtitle, $mNewtitle, $mPagetitle;
        var $mOldtext, $mNewtext;
        var $mOldUser, $mNewUser;
        var $mOldComment, $mNewComment;
        var $mOldPage, $mNewPage;
        var $mRcidMarkPatrolled;
+       var $mOldRev, $mNewRev;
+       var $mRevisionsLoaded = false; // Have the revisions been loaded
+       var $mTextLoaded = 0; // How many text blobs have been loaded, 0, 1 or 2?
        /**#@-*/
 
        /**
         * Constructor
+        * @param Title $titleObj Title object that the diff is associated with
         * @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;
+       function DifferenceEngine( $titleObj = null, $old = 0, $new = 0, $rcid = 0 ) {
+               $this->mTitle = $titleObj;
 
                if ( 'prev' == $new ) {
                        # Show diff between revision $old and the previous one.
@@ -42,14 +49,14 @@ class DifferenceEngine {
                        #
                        $this->mNewid = intval($old);
 
-                       $this->mOldid = $wgTitle->getPreviousRevisionID( $this->mNewid );
+                       $this->mOldid = $this->mTitle->getPreviousRevisionID( $this->mNewid );
 
                } elseif ( 'next' == $new ) {
                        # Show diff between revision $old and the previous one.
                        # Get previous one from DB.
                        #
                        $this->mOldid = intval($old);
-                       $this->mNewid = $wgTitle->getNextRevisionID( $this->mOldid );
+                       $this->mNewid = $this->mTitle->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".
@@ -64,9 +71,39 @@ class DifferenceEngine {
        }
 
        function showDiffPage() {
-               global $wgUser, $wgTitle, $wgOut, $wgContLang, $wgOnlySysopsCanPatrol, $wgUseRCPatrol;
+               global $wgUser, $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 );
+                       $url1=$this->mTitle->getFullURL("action=raw&oldid=".$this->mOldid);                     
+                       $url2=$this->mTitle->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
@@ -77,17 +114,21 @@ class DifferenceEngine {
                        return;
                }
 
-               $t = $wgTitle->getPrefixedText() . " (Diff: {$this->mOldid}, " .
+               $t = $this->mTitle->getPrefixedText() . " (Diff: {$this->mOldid}, " .
                  "{$this->mNewid})";
-               $mtext = wfMsg( 'missingarticle', $t );
+               $mtext = wfMsg( 'missingarticle', "<nowiki>$t</nowiki>" );
 
                $wgOut->setArticleFlag( false );
-               if ( ! $this->loadText() ) {
+               if ( ! $this->loadRevisionData() ) {
                        $wgOut->setPagetitle( wfMsg( 'errorpagetitle' ) );
-                       $wgOut->addHTML( $mtext );
+                       $wgOut->addWikitext( $mtext );
                        wfProfileOut( $fname );
                        return;
                }
+               if ( $this->mNewRev->isCurrent() ) {
+                       $wgOut->setArticleFlag( true );
+               }
+               
                $wgOut->suppressQuickbar();
 
                $oldTitle = $this->mOldPage->getPrefixedText();
@@ -122,10 +163,10 @@ class DifferenceEngine {
                        'target=' . urlencode($this->mOldUser) );
                $newContribs = $sk->makeKnownLinkObj( Title::makeTitle( NS_SPECIAL, 'Contributions' ), $contribs,
                        'target=' . urlencode($this->mNewUser) );
-               if ( !$this->mNewid && $wgUser->isAllowed('rollback') ) {
-                       $rollback = '&nbsp;&nbsp;&nbsp;<strong>[' . $sk->makeKnownLinkObj( $wgTitle, wfMsg( 'rollbacklink' ),
+               if ( $this->mNewRev->isCurrent() && $wgUser->isAllowed('rollback') ) {
+                       $rollback = '&nbsp;&nbsp;&nbsp;<strong>[' . $sk->makeKnownLinkObj( $this->mTitle, wfMsg( 'rollbacklink' ),
                                'action=rollback&from=' . urlencode($this->mNewUser) .
-                               '&token=' . urlencode( $wgUser->editToken( array( $wgTitle->getPrefixedText(), $this->mNewUser ) ) ) ) .
+                               '&token=' . urlencode( $wgUser->editToken( array( $this->mTitle->getPrefixedText(), $this->mNewUser ) ) ) ) .
                                ']</strong>';
                } else {
                        $rollback = '';
@@ -133,17 +174,19 @@ class DifferenceEngine {
                if ( $wgUseRCPatrol && $this->mRcidMarkPatrolled != 0 && $wgUser->isLoggedIn() &&
                     ( $wgUser->isAllowed('rollback') || !$wgOnlySysopsCanPatrol ) )
                {
-                       $patrol = ' [' . $sk->makeKnownLinkObj( $wgTitle, wfMsg( 'markaspatrolleddiff' ),
+                       $patrol = ' [' . $sk->makeKnownLinkObj( $this->mTitle, wfMsg( 'markaspatrolleddiff' ),
                                "action=markpatrolled&rcid={$this->mRcidMarkPatrolled}" ) . ']';
                } else {
                        $patrol = '';
                }
 
-               $prevlink = $sk->makeKnownLinkObj( $wgTitle, wfMsg( 'previousdiff' ), 'diff=prev&oldid='.$this->mOldid );
-               if ( $this->mNewid == 0 ) {
+               $prevlink = $sk->makeKnownLinkObj( $this->mTitle, wfMsgHtml( 'previousdiff' ),
+                       'diff=prev&oldid='.$this->mOldid, '', '', 'id="differences-prevlink"' );
+               if ( $this->mNewRev->isCurrent() ) {
                        $nextlink = '';
                } else {
-                       $nextlink = $sk->makeKnownLinkObj( $wgTitle, wfMsg( 'nextdiff' ), 'diff=next&oldid='.$this->mNewid );
+                       $nextlink = $sk->makeKnownLinkObj( $this->mTitle, wfMsgHtml( 'nextdiff' ),
+                               'diff=next&oldid='.$this->mNewid, '', '', 'id="differences-nextlink"' );
                }
 
                $oldHeader = "<strong>{$this->mOldtitle}</strong><br />$oldUserLink " .
@@ -153,11 +196,23 @@ class DifferenceEngine {
                        "($newUTLink | $newContribs) $rollback<br />" . $this->mNewComment .
                        '<br />' . $nextlink . $patrol;
 
-               DifferenceEngine::showDiff( $this->mOldtext, $this->mNewtext,
-                 $oldHeader, $newHeader );
+               $this->showDiff( $oldHeader, $newHeader );
                $wgOut->addHTML( "<hr /><h2>{$this->mPagetitle}</h2>\n" );
+
+               if( !$this->mNewRev->isCurrent() ) {
+                       $oldEditSectionSetting = $wgOut->mParserOptions->setEditSection( false );
+               }
+
+               $this->loadNewText();
+               if( is_object( $this->mNewRev ) ) {
+                       $wgOut->setRevisionId( $this->mNewRev->getId() );
+               }
                $wgOut->addWikiText( $this->mNewtext );
 
+               if( !$this->mNewRev->isCurrent() ) {
+                       $wgOut->mParserOptions->setEditSection( $oldEditSectionSetting );
+               }
+
                wfProfileOut( $fname );
        }
 
@@ -166,29 +221,29 @@ class DifferenceEngine {
         * contrast to normal "old revision" display style.
         */
        function showFirstRevision() {
-               global $wgOut, $wgTitle, $wgUser, $wgLang;
+               global $wgOut, $wgUser, $wgLang;
 
                $fname = 'DifferenceEngine::showFirstRevision';
                wfProfileIn( $fname );
 
-
-               $this->mOldid = $this->mNewid; # hack to make loadText() work.
-
                # Get article text from the DB
                #
-               if ( ! $this->loadText() ) {
-                       $t = $wgTitle->getPrefixedText() . " (Diff: {$this->mOldid}, " .
+               if ( ! $this->loadNewText() ) {
+                       $t = $this->mTitle->getPrefixedText() . " (Diff: {$this->mOldid}, " .
                          "{$this->mNewid})";
-                       $mtext = wfMsg( 'missingarticle', $t );
+                       $mtext = wfMsg( 'missingarticle', "<nowiki>$t</nowiki>" );
                        $wgOut->setPagetitle( wfMsg( 'errorpagetitle' ) );
-                       $wgOut->addHTML( $mtext );
+                       $wgOut->addWikitext( $mtext );
                        wfProfileOut( $fname );
                        return;
                }
+               if ( $this->mNewRev->isCurrent() ) {
+                       $wgOut->setArticleFlag( true );
+               }
 
                # Check if user is allowed to look at this page. If not, bail out.
                #
-               if ( !( $this->mOldPage->userCanRead() ) ) {
+               if ( !( $this->mTitle->userCanRead() ) ) {
                        $wgOut->loginToUse();
                        $wgOut->output();
                        wfProfileOut( $fname );
@@ -203,7 +258,7 @@ class DifferenceEngine {
                $userLink = $sk->makeLinkObj( Title::makeTitleSafe( NS_USER, $this->mOldUser ), $this->mOldUser );
                $contribs = $sk->makeKnownLinkObj( Title::makeTitle( NS_SPECIAL, 'Contributions' ), wfMsg( 'contribslink' ),
                        'target=' . urlencode($this->mOldUser) );
-               $nextlink = $sk->makeKnownLinkObj( $wgTitle, wfMsg( 'nextdiff' ), 'diff=next&oldid='.$this->mNewid );
+               $nextlink = $sk->makeKnownLinkObj( $this->mTitle, wfMsgHtml( 'nextdiff' ), 'diff=next&oldid='.$this->mNewid, '', '', 'id="differences-nextlink"' );
                $header = "<div class=\"firstrevisionheader\" style=\"text-align: center\"><strong>{$this->mOldtitle}</strong><br />$userLink " .
                        "($uTLink | $contribs)<br />" . $this->mOldComment .
                        '<br />' . $nextlink. "</div>\n";
@@ -217,28 +272,68 @@ class DifferenceEngine {
                # Show current revision
                #
                $wgOut->addHTML( "<hr /><h2>{$this->mPagetitle}</h2>\n" );
+               if( is_object( $this->mNewRev ) ) {
+                       $wgOut->setRevisionId( $this->mNewRev->getId() );
+               }
                $wgOut->addWikiText( $this->mNewtext );
 
                wfProfileOut( $fname );
        }
 
-       function showDiff( $otext, $ntext, $otitle, $ntitle ) {
+       /**
+        * Get the diff text, send it to $wgOut
+        * Returns false if the diff could not be generated, otherwise returns true
+        */
+       function showDiff( $otitle, $ntitle ) {
                global $wgOut;
-               $wgOut->addHTML( DifferenceEngine::getDiff( $otext, $ntext, $otitle, $ntitle ) );
+               $diff = $this->getDiff( $otitle, $ntitle );
+               if ( $diff === false ) {
+                       $wgOut->addWikitext( wfMsg( 'missingarticle', "<nowiki>$t</nowiki>" ) );
+                       return false;
+               } else {
+                       $wgOut->addHTML( $diff );
+                       return true;
+               }
        }
-       
-       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='';
+
+       /**
+        * Get diff table, including header
+        * Note that the interface has changed, it's no longer static.
+        * Returns false on error
+        */
+       function getDiff( $otitle, $ntitle ) {
+               $body = $this->getDiffBody();
+               if ( $body === false ) {
+                       return false;
+               } else {
+                       return $this->addHeader( $body, $otitle, $ntitle );
+               }
+       }
+
+       /**
+        * Get the diff table body, without header
+        * Returns false on error
+        */
+       function getDiffBody() {
+               global $wgUseExternalDiffEngine, $wgContLang, $wgMemc, $wgDBname;
+               
+               // Cacheable?
+               $key = false;
+               if ( $this->mOldid && $this->mNewid ) {
+                       // Try cache
+                       $key = "$wgDBname:diff:oldid:{$this->mOldid}:newid:{$this->mNewid}";
+                       $difftext = $wgMemc->get( $key );
+                       if ( $difftext ) {
+                               return $difftext;
+                       }
+               }
+               
+               if ( !$this->loadText() ) {
+                       return false;
+               }
+               
+               $otext = $wgContLang->segmentForDiff($this->mOldtext);
+               $ntext = $wgContLang->segmentForDiff($this->mNewtext);
                if ( $wgUseExternalDiffEngine ) {
                        # For historical reasons, external diff engine expects
                        # input text to be HTML-escaped already
@@ -256,69 +351,154 @@ class DifferenceEngine {
                        $difftext = $formatter->format( $diffs );
                }
                $difftext = $wgContLang->unsegmentForDiff($difftext);
-               $out .= $difftext."</table>\n";
+
+               // Save to cache for 7 days
+               if ( $key !== false ) {
+                       $wgMemc->set( $key, $difftext, 7*86400 );
+               }
+               return $difftext;
+       }
+
+       /**
+        * Add the header to a diff body
+        */
+       function addHeader( $diff, $otitle, $ntitle ) {
+               $out = "
+                       <table border='0' width='98%' cellpadding='0' cellspacing='4' class='diff'>
+                       <tr>
+                               <td colspan='2' width='50%' align='center' class='diff-otitle'>{$otitle}</td>
+                               <td colspan='2' width='50%' align='center' class='diff-ntitle'>{$ntitle}</td>
+                       </tr>
+                       $diff
+                       </table>
+               ";
                return $out;
        }
 
+       /** 
+        * Use specified text instead of loading from the database
+        */
+       function setText( $oldText, $newText ) {
+               $this->mOldtext = $oldText;
+               $this->mNewtext = $newText;
+               $this->mTextLoaded = 2;
+       }
+
        /**
-        * Load the text of the articles to compare.  If newid is 0, then compare
+        * Load revision metadata for the specified articles. 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';
+        * value of newid). 
+        *
+        * If oldid is false, leave the corresponding revision object set 
+        * to false. This is impossible via ordinary user input, and is provided for 
+        * API convenience. 
+        */
+       function loadRevisionData() {
+               global $wgLang;
+               if ( $this->mRevisionsLoaded ) {
+                       return true;
+               } else {
+                       // Whether it succeeds or fails, we don't want to try again
+                       $this->mRevisionsLoaded = true;
+               }
 
-               $dbr =& wfGetDB( DB_SLAVE );
+               // Load the new revision object
                if( $this->mNewid ) {
-                       $this->newRev =& Revision::newFromId( $this->mNewid );
+                       $this->mNewRev = Revision::newFromId( $this->mNewid );
                } else {
-                       $this->newRev =& Revision::newFromTitle( $wgTitle );
+                       $this->mNewRev = Revision::newFromTitle( $this->mTitle );
                }
-               if( is_null( $this->newRev ) ) {
+
+               if( is_null( $this->mNewRev ) ) {
                        return false;
                }
-               
-               if( $this->newRev->isCurrent() ) {
+
+               // Set assorted variables
+               if( $this->mNewRev->isCurrent() ) {
                        $this->mPagetitle = htmlspecialchars( wfMsg( 'currentrev' ) );
-                       $this->mNewPage = $wgTitle;
+                       $this->mNewPage = $this->mTitle;
                        $newLink = $this->mNewPage->escapeLocalUrl();
                        $this->mNewtitle = "<a href='$newLink'>{$this->mPagetitle}</a>";
                } else {
-                       $this->mNewPage = $this->newRev->getTitle();
+                       $this->mNewPage = $this->mNewRev->getTitle();
                        $newLink = $this->mNewPage->escapeLocalUrl ('oldid=' . $this->mNewid );
-                       $t = $wgLang->timeanddate( $this->newRev->getTimestamp(), true );
+                       $t = $wgLang->timeanddate( $this->mNewRev->getTimestamp(), true );
                        $this->mPagetitle = htmlspecialchars( wfMsg( 'revisionasof', $t ) );
                        $this->mNewtitle = "<a href='$newLink'>{$this->mPagetitle}</a>";
                }
+                       
+               $this->mNewUser = $this->mNewRev->getUserText();
+               $this->mNewComment = $this->mNewRev->getComment();
                
+               // Load the old revision object
+               $this->mOldRev = false;
                if( $this->mOldid ) {
-                       $this->oldRev =& Revision::newFromId( $this->mOldid );
-               } else {
-                       $this->oldRev =& $this->newRev->getPrevious();
-                       $this->mOldid = $this->oldRev->getId();
-               }
-               if( is_null( $this->oldRev ) ) {
+                       $this->mOldRev = Revision::newFromId( $this->mOldid );
+               } elseif ( $this->mOldid === 0 ) {
+                       $this->mOldRev = $this->mNewRev->getPrevious();
+                       $this->mOldid = $this->mOldRev->getId();
+               }/* elseif ( $this->mOldid === false ) leave mOldRev false; */
+
+               if( is_null( $this->mOldRev ) ) {
                        return false;
                }
-                       
-               $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>';
+               if ( $this->mOldRev ) {
+                       $this->mOldPage = $this->mOldRev->getTitle();
+
+                       $t = $wgLang->timeanddate( $this->mOldRev->getTimestamp(), true );
+                       $oldLink = $this->mOldPage->escapeLocalUrl( 'oldid=' . $this->mOldid );
+                       $this->mOldtitle = "<a href='$oldLink'>" . htmlspecialchars( wfMsg( 'revisionasof', $t ) ) . '</a>';
+
+                       
+                       $this->mOldUser = $this->mOldRev->getUserText();
+                       $this->mOldComment = $this->mOldRev->getComment();
+               }
                
-               $this->mNewUser = $this->newRev->getUserText();
-               $this->mNewComment = $this->newRev->getComment();
-               $this->mNewtext = $this->newRev->getText();
+               return true;
+       }
+
+       /**
+        * Load the text of the revisions, as well as revision data.
+        */
+       function loadText() {
+               if ( $this->mTextLoaded == 2 ) {
+                       return true;
+               } else {
+                       // Whether it succeeds or fails, we don't want to try again
+                       $this->mTextLoaded = 2;
+               }
                
-               $this->mOldUser = $this->oldRev->getUserText();
-               $this->mOldComment = $this->oldRev->getComment();
-               $this->mOldtext = $this->oldRev->getText();
+               if ( !$this->loadRevisionData() ) {
+                       return false;
+               }
+               if ( $this->mOldRev ) {
+                       $this->mOldtext = $this->mOldRev->getText();
+               }
+               if ( $this->mNewRev ) {
+                       $this->mNewtext = $this->mNewRev->getText();
+               }
+               return true;
+       }
 
+       /**
+        * Load the text of the new revision, not the old one
+        */
+       function loadNewText() {
+               if ( $this->mTextLoaded >= 1 ) {
+                       return true;
+               } else {
+                       $this->mTextLoaded = 1;
+               }
+               if ( !$this->loadRevisionData() ) {
+                       return false;
+               }
+               $this->mNewtext = $this->mNewRev->getText();
                return true;
        }
+               
+       
 }
 
 // A PHP diff engine for phpwiki. (Taken from phpwiki-1.3.3)
@@ -449,7 +629,9 @@ class _DiffOp_Change extends _DiffOp {
  * closingly, some ideas (subdivision by NCHUNKS > 2, and some optimizations)
  * are my own.
  *
- * @author Geoffrey T. Dairiki
+ * Line length limits for robustness added by Tim Starling, 2005-08-31
+ *
+ * @author Geoffrey T. Dairiki, Tim Starling
  * @access private
  * @package MediaWiki 
  * @subpackage DifferenceEngine
@@ -485,19 +667,21 @@ class _DiffEngine
                }
 
                // Ignore lines which do not exist in both files.
-               for ($xi = $skip; $xi < $n_from - $endskip; $xi++)
-                       $xhash[$from_lines[$xi]] = 1;
+               for ($xi = $skip; $xi < $n_from - $endskip; $xi++) {
+                       $xhash[$this->_line_hash($from_lines[$xi])] = 1;
+               }
+               
                for ($yi = $skip; $yi < $n_to - $endskip; $yi++) {
                        $line = $to_lines[$yi];
-                       if ( ($this->ychanged[$yi] = empty($xhash[$line])) )
+                       if ( ($this->ychanged[$yi] = empty($xhash[$this->_line_hash($line)])) )
                                continue;
-                       $yhash[$line] = 1;
+                       $yhash[$this->_line_hash($line)] = 1;
                        $this->yv[] = $line;
                        $this->yind[] = $yi;
                }
                for ($xi = $skip; $xi < $n_from - $endskip; $xi++) {
                        $line = $from_lines[$xi];
-                       if ( ($this->xchanged[$xi] = empty($yhash[$line])) )
+                       if ( ($this->xchanged[$xi] = empty($yhash[$this->_line_hash($line)])) )
                                continue;
                        $this->xv[] = $line;
                        $this->xind[] = $xi;
@@ -547,6 +731,17 @@ class _DiffEngine
                return $edits;
        }
 
+       /**
+        * Returns the whole line if it's small enough, or the MD5 hash otherwise
+        */
+       function _line_hash( $line ) {
+               if ( strlen( $line ) > MAX_DIFF_XREF_LENGTH ) {
+                       return md5( $line );
+               } else {
+                       return $line;
+               }
+       }
+       
 
        /* Divide the Largest Common Subsequence (LCS) of the sequences
         * [XOFF, XLIM) and [YOFF, YLIM) into NCHUNKS approximately equally
@@ -1302,7 +1497,6 @@ class WordLevelDiff extends MappedDiff
                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( $fname );
@@ -1311,14 +1505,33 @@ class WordLevelDiff extends MappedDiff
        function _split($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(''));
+
+               $words = array();
+               $stripped = array();
+               $first = true;
+               foreach ( $lines as $line ) {
+                       # If the line is too long, just pretend the entire line is one big word
+                       # This prevents resource exhaustion problems
+                       if ( $first ) {
+                               $first = false;
+                       } else {
+                               $words[] = "\n";
+                               $stripped[] = "\n";
+                       }
+                       if ( strlen( $line ) > MAX_DIFF_LINE ) {
+                               $words[] = $line;
+                               $stripped[] = $line;
+                       } else {
+                               if (preg_match_all('/ ( [^\S\n]+ | [0-9_A-Za-z\x80-\xff]+ | . ) (?: (?!< \n) [^\S\n])? /xs',
+                                       $line, $m)) 
+                               {
+                                       $words = array_merge( $words, $m[0] );
+                                       $stripped = array_merge( $stripped, $m[1] );
+                               }
+                       }
                }
                wfProfileOut( $fname );
-               return array($m[0], $m[1]);
+               return array($words, $stripped);
        }
 
        function orig () {