X-Git-Url: https://git.heureux-cyclage.org/?a=blobdiff_plain;f=includes%2FDifferenceEngine.php;h=e6218b6d9c1600a334dd0e26326e177e12085300;hb=5fa40fe0fbfb379022430c24fcf66392e229d9a5;hp=198c9b3931c8903c6555880dd80fbc5218a26a22;hpb=332a0cf2684024869536a2af1ef83990efcb7b3c;p=lhc%2Fweb%2Fwiklou.git

diff --git a/includes/DifferenceEngine.php b/includes/DifferenceEngine.php
index 198c9b3931..e6218b6d9c 100644
--- a/includes/DifferenceEngine.php
+++ b/includes/DifferenceEngine.php
@@ -1,47 +1,53 @@
 <?php
 /**
  * See diff.doc
- * @package MediaWiki 
+ * @addtogroup DifferenceEngine
  */
 
 /**
  * @todo document
- * @package MediaWiki
+ * @public
+ * @addtogroup 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 )
-	{
-		global $wgTitle;
-		if ( 'prev' == $new ) {
+	/**#@+
+	 * @private
+	 */
+	var $mOldid, $mNewid, $mTitle;
+	var $mOldtitle, $mNewtitle, $mPagetitle;
+	var $mOldtext, $mNewtext;
+	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 $titleObj Title object that the diff is associated with
+	 * @param $old Integer: old ID we want to show and diff with.
+	 * @param $new String: either 'prev' or 'next'.
+	 * @param $rcid Integer: ??? FIXME (default 0)
+	 */
+	function DifferenceEngine( $titleObj = null, $old = 0, $new = 0, $rcid = 0 ) {
+		$this->mTitle = $titleObj;
+		wfDebug("DifferenceEngine old '$old' new '$new' rcid '$rcid'\n");
+
+		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 = $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);
-			$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 = $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".
@@ -49,39 +55,72 @@ 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, $wgContLang, $wgOnlySysopsCanPatrol, $wgUseRCPatrol;
+	function showDiffPage( $diffOnly = false ) {
+		global $wgUser, $wgOut, $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;
+		}
+
+		$wgOut->setArticleFlag( false );
+		if ( ! $this->loadRevisionData() ) {
+			$t = $this->mTitle->getPrefixedText() . " (Diff: {$this->mOldid}, {$this->mNewid})";
+			$mtext = wfMsg( 'missingarticle', "<nowiki>$t</nowiki>" );
+			$wgOut->setPagetitle( wfMsg( 'errorpagetitle' ) );
+			$wgOut->addWikitext( $mtext );
+			wfProfileOut( $fname );
+			return;
+		}
+		
+		wfRunHooks( 'DiffViewHeader', array( $this, $this->mOldRev, $this->mNewRev ) );
+
+		if ( $this->mNewRev->isCurrent() ) {
+			$wgOut->setArticleFlag( true );
+		}
+
 		# 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
 		# is the first version of that article. In that case, V' does not exist.
 		if ( $this->mOldid === false ) {
 			$this->showFirstRevision();
+			$this->renderNewRevision();  // should we respect $diffOnly here or not?
 			wfProfileOut( $fname );
 			return;
 		}
 
-		$t = $wgTitle->getPrefixedText() . " (Diff: {$this->mOldid}, " .
-		  "{$this->mNewid})";
-		$mtext = wfMsg( 'missingarticle', $t );
-
-		$wgOut->setArticleFlag( false );
-		if ( ! $this->loadText() ) {
-			$wgOut->setPagetitle( wfMsg( 'errorpagetitle' ) );
-			$wgOut->addHTML( $mtext );
-			wfProfileOut( $fname );
-			return;
-		}
 		$wgOut->suppressQuickbar();
 
 		$oldTitle = $this->mOldPage->getPrefixedText();
@@ -92,7 +131,7 @@ class DifferenceEngine {
 			$wgOut->setPageTitle( $oldTitle . ', ' . $newTitle );
 		}
 		$wgOut->setSubtitle( wfMsg( 'difference' ) );
-		$wgOut->setRobotpolicy( 'noindex,follow' );
+		$wgOut->setRobotpolicy( 'noindex,nofollow' );
 
 		if ( !( $this->mOldPage->userCanRead() && $this->mNewPage->userCanRead() ) ) {
 			$wgOut->loginToUse();
@@ -102,85 +141,117 @@ class DifferenceEngine {
 		}
 
 		$sk = $wgUser->getSkin();
-		$talk = $wgContLang->getNsText( NS_TALK );
-		$contribs = wfMsg( 'contribslink' );
-
-		$this->mOldComment = $sk->formatComment($this->mOldComment);
-		$this->mNewComment = $sk->formatComment($this->mNewComment);
-
-		$oldUserLink = $sk->makeLinkObj( Title::makeTitleSafe( NS_USER, $this->mOldUser ), $this->mOldUser );
-		$newUserLink = $sk->makeLinkObj( Title::makeTitleSafe( NS_USER, $this->mNewUser ), $this->mNewUser );
-		$oldUTLink = $sk->makeLinkObj( Title::makeTitleSafe( NS_USER_TALK, $this->mOldUser ), $talk );
-		$newUTLink = $sk->makeLinkObj( Title::makeTitleSafe( NS_USER_TALK, $this->mNewUser ), $talk );
-		$oldContribs = $sk->makeKnownLinkObj( Title::makeTitle( NS_SPECIAL, 'Contributions' ), $contribs,
-			'target=' . urlencode($this->mOldUser) );
-		$newContribs = $sk->makeKnownLinkObj( Title::makeTitle( NS_SPECIAL, 'Contributions' ), $contribs,
-			'target=' . urlencode($this->mNewUser) );
-		if ( !$this->mNewid && $wgUser->isSysop() ) {
-			$rollback = '&nbsp;&nbsp;&nbsp;<strong>[' . $sk->makeKnownLinkObj( $wgTitle, wfMsg( 'rollbacklink' ),
-				'action=rollback&from=' . urlencode($this->mNewUser) ) . ']</strong>';
+
+		if ( $this->mNewRev->isCurrent() && $wgUser->isAllowed('rollback') ) {
+			$rollback = '&nbsp;&nbsp;&nbsp;' . $sk->generateRollback( $this->mNewRev );
 		} else {
 			$rollback = '';
 		}
-		if ( $wgUseRCPatrol && $this->mRcidMarkPatrolled != 0 && $wgUser->getID() != 0 &&
-		     ( $wgUser->isSysop() || !$wgOnlySysopsCanPatrol ) )
-		{
-			$patrol = ' [' . $sk->makeKnownLinkObj( $wgTitle, wfMsg( 'markaspatrolleddiff' ),
-				"action=markpatrolled&rcid={$this->mRcidMarkPatrolled}" ) . ']';
+		if( $wgUseRCPatrol && $this->mRcidMarkPatrolled != 0 && $wgUser->isAllowed( 'patrol' ) ) {
+			$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 ) {
-			$nextlink = '';
+		$prevlink = $sk->makeKnownLinkObj( $this->mTitle, wfMsgHtml( 'previousdiff' ),
+			'diff=prev&oldid='.$this->mOldid, '', '', 'id="differences-prevlink"' );
+		if ( $this->mNewRev->isCurrent() ) {
+			$nextlink = '&nbsp;';
 		} 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"' );
+		}
+
+		$oldminor = '';
+		$newminor = '';
+
+		if ($this->mOldRev->mMinorEdit == 1) {
+			$oldminor = wfElement( 'span', array( 'class' => 'minor' ),
+				wfMsg( 'minoreditletter') ) . ' ';
 		}
 
-		$oldHeader = "<strong>{$this->mOldtitle}</strong><br />$oldUserLink " .
-			"($oldUTLink | $oldContribs)<br />" . $this->mOldComment .
-			'<br />' . $prevlink;
-		$newHeader = "<strong>{$this->mNewtitle}</strong><br />$newUserLink " .
-			"($newUTLink | $newContribs) $rollback<br />" . $this->mNewComment .
-			'<br />' . $nextlink . $patrol;
+		if ($this->mNewRev->mMinorEdit == 1) {
+			$newminor = wfElement( 'span', array( 'class' => 'minor' ),
+			wfMsg( 'minoreditletter') ) . ' ';
+		}
+
+		$oldHeader = "<strong>{$this->mOldtitle}</strong><br />" .
+			$sk->revUserTools( $this->mOldRev ) . "<br />" .
+			$oldminor . $sk->revComment( $this->mOldRev, !$diffOnly ) . "<br />" .
+			$prevlink;
+		$newHeader = "<strong>{$this->mNewtitle}</strong><br />" .
+			$sk->revUserTools( $this->mNewRev ) . " $rollback<br />" .
+			$newminor . $sk->revComment( $this->mNewRev, !$diffOnly ) . "<br />" .
+			$nextlink . $patrol;
+
+		$this->showDiff( $oldHeader, $newHeader );
+
+		if ( !$diffOnly )
+			$this->renderNewRevision();
+
+		wfProfileOut( $fname );
+	}
+
+	/**
+	 * Show the new revision of the page.
+	 */
+	function renderNewRevision() {
+		global $wgOut;
+		$fname = 'DifferenceEngine::renderNewRevision';
+		wfProfileIn( $fname );
 
-		DifferenceEngine::showDiff( $this->mOldtext, $this->mNewtext,
-		  $oldHeader, $newHeader );
 		$wgOut->addHTML( "<hr /><h2>{$this->mPagetitle}</h2>\n" );
-		$wgOut->addWikiText( $this->mNewtext );
+		#add deleted rev tag if needed
+		if ( !$this->mNewRev->userCan(Revision::DELETED_TEXT) ) {
+		  	$wgOut->addWikiText( wfMsg( 'rev-deleted-text-permission' ) );
+		}
+
+		if( !$this->mNewRev->isCurrent() ) {
+			$oldEditSectionSetting = $wgOut->parserOptions()->setEditSection( false );
+		}
+
+		$this->loadNewText();
+		if( is_object( $this->mNewRev ) ) {
+			$wgOut->setRevisionId( $this->mNewRev->getId() );
+		}
+
+		$wgOut->addWikiTextTidy( $this->mNewtext );
+
+		if( !$this->mNewRev->isCurrent() ) {
+			$wgOut->parserOptions()->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()
-	{
-		global $wgOut, $wgTitle, $wgUser, $wgLang;
+	/**
+	 * Show the first revision of an article. Uses normal diff headers in
+	 * contrast to normal "old revision" display style.
+	 */
+	function showFirstRevision() {
+		global $wgOut, $wgUser;
 
 		$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 );
@@ -191,140 +262,387 @@ class DifferenceEngine {
 		#
 		$sk = $wgUser->getSkin();
 
-		$uTLink = $sk->makeLinkObj( Title::makeTitleSafe( NS_USER_TALK, $this->mOldUser ),  $wgLang->getNsText( NS_TALK ) );
-		$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 );
-		$header = "<div class=\"firstrevisionheader\" style=\"text-align: center\"><strong>{$this->mOldtitle}</strong><br />$userLink " .
-			"($uTLink | $contribs)<br />" . $this->mOldComment .
-			'<br />' . $nextlink. "</div>\n";
+		$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 />" .
+			$sk->revUserTools( $this->mNewRev ) . "<br />" .
+			$sk->revComment( $this->mNewRev ) . "<br />" .
+			$nextlink . "</div>\n";
 
 		$wgOut->addHTML( $header );
 
 		$wgOut->setSubtitle( wfMsg( 'difference' ) );
-		$wgOut->setRobotpolicy( 'noindex,follow' );
+		$wgOut->setRobotpolicy( 'noindex,nofollow' );
 
+		wfProfileOut( $fname );
+	}
 
-		# Show current revision
-		#
-		$wgOut->addHTML( "<hr /><h2>{$this->mPagetitle}</h2>\n" );
-		$wgOut->addWikiText( $this->mNewtext );
+	/**
+	 * 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;
+		$diff = $this->getDiff( $otitle, $ntitle );
+		if ( $diff === false ) {
+			$wgOut->addWikitext( wfMsg( 'missingarticle', "<nowiki>(fixme, bug)</nowiki>" ) );
+			return false;
+		} else {
+			$wgOut->addHTML( $diff );
+			return true;
+		}
+	}
+
+	/**
+	 * 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 {
+			$multi = $this->getMultiNotice();
+			return $this->addHeader( $body, $otitle, $ntitle, $multi );
+		}
+	}
+
+	/**
+	 * Get the diff table body, without header
+	 * Results are cached
+	 * Returns false on error
+	 */
+	function getDiffBody() {
+		global $wgMemc;
+		$fname = 'DifferenceEngine::getDiffBody';
+		wfProfileIn( $fname );
+		
+		// Cacheable?
+		$key = false;
+		if ( $this->mOldid && $this->mNewid ) {
+			// Try cache
+			$key = wfMemcKey( 'diff', 'oldid', $this->mOldid, 'newid', $this->mNewid );
+			$difftext = $wgMemc->get( $key );
+			if ( $difftext ) {
+				wfIncrStats( 'diff_cache_hit' );
+				$difftext = $this->localiseLineNumbers( $difftext );
+				$difftext .= "\n<!-- diff cache key $key -->\n";
+				wfProfileOut( $fname );
+				return $difftext;
+			}
+		}
+
+		#loadtext is permission safe, this just clears out the diff
+		if ( !$this->loadText() ) {
+			wfProfileOut( $fname );
+			return false;
+		} else if ( $this->mOldRev && !$this->mOldRev->userCan(Revision::DELETED_TEXT) ) {
+		  return '';
+		} else if ( $this->mNewRev && !$this->mNewRev->userCan(Revision::DELETED_TEXT) ) {
+		  return '';
+		}
 
+		$difftext = $this->generateDiffBody( $this->mOldtext, $this->mNewtext );
+		
+		// Save to cache for 7 days
+		if ( $key !== false && $difftext !== false ) {
+			wfIncrStats( 'diff_cache_miss' );
+			$wgMemc->set( $key, $difftext, 7*86400 );
+		} else {
+			wfIncrStats( 'diff_uncacheable' );
+		}
+		// Replace line numbers with the text in the user's language
+		if ( $difftext !== false ) {
+			$difftext = $this->localiseLineNumbers( $difftext );
+		}
 		wfProfileOut( $fname );
+		return $difftext;
 	}
 
-	function showDiff( $otext, $ntext, $otitle, $ntitle )
-	{
-		global $wgOut, $wgUseExternalDiffEngine;
+	/**
+	 * Generate a diff, no caching
+	 * $otext and $ntext must be already segmented
+	 */
+	function generateDiffBody( $otext, $ntext ) {
+		global $wgExternalDiffEngine, $wgContLang;
+		$fname = 'DifferenceEngine::generateDiffBody';
+
+		$otext = str_replace( "\r\n", "\n", $otext );
+		$ntext = str_replace( "\r\n", "\n", $ntext );
+		
+		if ( $wgExternalDiffEngine == 'wikidiff' ) {
+			# For historical reasons, external diff engine expects
+			# input text to be HTML-escaped already
+			$otext = htmlspecialchars ( $wgContLang->segmentForDiff( $otext ) );
+			$ntext = htmlspecialchars ( $wgContLang->segmentForDiff( $ntext ) );
+			if( !function_exists( 'wikidiff_do_diff' ) ) {
+				dl('php_wikidiff.so');
+			}
+			return $wgContLang->unsegementForDiff( wikidiff_do_diff( $otext, $ntext, 2 ) );
+		}
+		
+		if ( $wgExternalDiffEngine == 'wikidiff2' ) {
+			# Better external diff engine, the 2 may some day be dropped
+			# This one does the escaping and segmenting itself
+			if ( !function_exists( 'wikidiff2_do_diff' ) ) {
+				wfProfileIn( "$fname-dl" );
+				@dl('php_wikidiff2.so');
+				wfProfileOut( "$fname-dl" );
+			}
+			if ( function_exists( 'wikidiff2_do_diff' ) ) {
+				wfProfileIn( 'wikidiff2_do_diff' );
+				$text = wikidiff2_do_diff( $otext, $ntext, 2 );
+				wfProfileOut( 'wikidiff2_do_diff' );
+				return $text;
+			}
+		}
+		if ( $wgExternalDiffEngine !== false ) {
+			# Diff via the shell
+			global $wgTmpDirectory;
+			$tempName1 = tempnam( $wgTmpDirectory, 'diff_' );
+			$tempName2 = tempnam( $wgTmpDirectory, 'diff_' );
+
+			$tempFile1 = fopen( $tempName1, "w" );
+			if ( !$tempFile1 ) {
+				wfProfileOut( $fname );
+				return false;
+			}
+			$tempFile2 = fopen( $tempName2, "w" );
+			if ( !$tempFile2 ) {
+				wfProfileOut( $fname );
+				return false;
+			}
+			fwrite( $tempFile1, $otext );
+			fwrite( $tempFile2, $ntext );
+			fclose( $tempFile1 );
+			fclose( $tempFile2 );
+			$cmd = wfEscapeShellArg( $wgExternalDiffEngine, $tempName1, $tempName2 );
+			wfProfileIn( "$fname-shellexec" );
+			$difftext = wfShellExec( $cmd );
+			wfProfileOut( "$fname-shellexec" );
+			unlink( $tempName1 );
+			unlink( $tempName2 );
+			return $difftext;
+		}
+		
+		# Native PHP diff
+		$ota = explode( "\n", $wgContLang->segmentForDiff( $otext ) );
+		$nta = explode( "\n", $wgContLang->segmentForDiff( $ntext ) );
+		$diffs = new Diff( $ota, $nta );
+		$formatter = new TableDiffFormatter();
+		return $wgContLang->unsegmentForDiff( $formatter->format( $diffs ) );
+	}
+		
+
+	/**
+	 * Replace line numbers with the text in the user's language
+	 */
+	function localiseLineNumbers( $text ) {
+		return preg_replace_callback( '/<!--LINE (\d+)-->/',
+			array( &$this, 'localiseLineNumbersCb' ), $text );
+	}
+
+	function localiseLineNumbersCb( $matches ) {
+		global $wgLang;
+		return wfMsgExt( 'lineno', array('parseinline'), $wgLang->formatNum( $matches[1] ) );
+	}
+
+	
+	/**
+	 * If there are revisions between the ones being compared, return a note saying so.
+	 */
+	function getMultiNotice() {
+		if ( !is_object($this->mOldRev) || !is_object($this->mNewRev) )
+			return '';
+		
+		if( !$this->mOldPage->equals( $this->mNewPage ) ) {
+			// Comparing two different pages? Count would be meaningless.
+			return '';
+		}
+		
+		$oldid = $this->mOldRev->getId();
+		$newid = $this->mNewRev->getId();
+		if ( $oldid > $newid ) {
+			$tmp = $oldid; $oldid = $newid; $newid = $tmp;
+		}
+
+		$n = $this->mTitle->countRevisionsBetween( $oldid, $newid );
+		if ( !$n )
+			return '';
+
+		return wfMsgExt( 'diff-multi', array( 'parseinline' ), $n );
+	}
 
-		$wgOut->addHTML( "
+
+	/**
+	 * Add the header to a diff body
+	 */
+	function addHeader( $diff, $otitle, $ntitle, $multi = '' ) {
+		global $wgOut;
+	
+		if ( $this->mOldRev && $this->mOldRev->isDeleted(Revision::DELETED_TEXT) ) {
+		   $otitle = '<span class="history-deleted">'.$otitle.'</span>';
+		}
+		if ( $this->mNewRev && $this->mNewRev->isDeleted(Revision::DELETED_TEXT) ) {
+		   $ntitle = '<span class="history-deleted">'.$ntitle.'</span>';
+		}
+		$header = "
 			<table border='0' width='98%' cellpadding='0' cellspacing='4' class='diff'>
 			<tr>
 				<td colspan='2' width='50%' align='center' class='diff-otitle'>{$otitle}</td>
 				<td colspan='2' width='50%' align='center' class='diff-ntitle'>{$ntitle}</td>
 			</tr>
-		" );
+		";
 
-		if ( $wgUseExternalDiffEngine ) {
-			# 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 ) );
-			dl('php_wikidiff.so');
-			$wgOut->addHTML( wikidiff_do_diff( $otext, $ntext, 2) );
+		if ( $multi != '' )
+			$header .= "<tr><td colspan='4' align='center' class='diff-multi'>{$multi}</td></tr>";
+
+		return $header . $diff . "</table>";
+	}
+
+	/**
+	 * Use specified text instead of loading from the database
+	 */
+	function setText( $oldText, $newText ) {
+		$this->mOldtext = $oldText;
+		$this->mNewtext = $newText;
+		$this->mTextLoaded = 2;
+	}
+
+	/**
+	 * 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).
+	 *
+	 * 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 {
-			$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();
-			$formatter->format( $diffs );
-		}
-		$wgOut->addHTML( "</table>\n" );
-	}
-
-	# 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 ) {
-			$wgOut->setArticleFlag( true );
-			$newLink = $wgTitle->getLocalUrl();
-			$this->mPagetitle = wfMsg( 'currentrev' );
-			$this->mNewtitle = "<a href='$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 ) {
-				wfDebug( "Unable to load cur_id $id\n" );
-				return false;
-			}
+			// Whether it succeeds or fails, we don't want to try again
+			$this->mRevisionsLoaded = true;
+		}
+
+		// Load the new revision object
+		if( $this->mNewid ) {
+			$this->mNewRev = Revision::newFromId( $this->mNewid );
+		} else {
+			$this->mNewRev = Revision::newFromTitle( $this->mTitle );
+		}
+
+		if( is_null( $this->mNewRev ) ) {
+			return false;
+		}
+
+		// Set assorted variables
+		$timestamp = $wgLang->timeanddate( $this->mNewRev->getTimestamp(), true );
+		$this->mNewPage = $this->mNewRev->getTitle();
+		if( $this->mNewRev->isCurrent() ) {
+			$newLink = $this->mNewPage->escapeLocalUrl();
+			$this->mPagetitle = htmlspecialchars( wfMsg( 'currentrev' ) );
+			$newEdit = $this->mNewPage->escapeLocalUrl( 'action=edit' );
+			$newUndo = $this->mNewPage->escapeLocalUrl( 'action=edit&undo=' . $this->mNewid );
+
+			$this->mNewtitle = "<a href='$newLink'>{$this->mPagetitle}</a> ($timestamp)"
+				. " (<a href='$newEdit'>" . htmlspecialchars( wfMsg( 'editold' ) ) . "</a>)"
+				. " (<a href='$newUndo'>" . htmlspecialchars( wfMsg( 'editundo' ) ) . "</a>)";
 
-			$this->mNewPage = &$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 );
+			$newLink = $this->mNewPage->escapeLocalUrl( 'oldid=' . $this->mNewid );
+			$newEdit = $this->mNewPage->escapeLocalUrl( 'action=edit&oldid=' . $this->mNewid );
+			$newUndo = $this->mNewPage->escapeLocalUrl( 'action=edit&undo=' . $this->mNewid );
+			$this->mPagetitle = htmlspecialchars( wfMsg( 'revisionasof', $timestamp ) );
+
+			$this->mNewtitle = "<a href='$newLink'>{$this->mPagetitle}</a>"
+				. " (<a href='$newEdit'>" . htmlspecialchars( wfMsg( 'editold' ) ) . "</a>)"
+				. " (<a href='$newUndo'>" . htmlspecialchars( wfMsg( 'editundo' ) ) . "</a>)";
+		}
 
-			if ( $s === false ) {
-				wfDebug( "Unable to load old_id {$this->mNewid}\n" );
-				return false;
+		// Load the old revision object
+		$this->mOldRev = false;
+		if( $this->mOldid ) {
+			$this->mOldRev = Revision::newFromId( $this->mOldid );
+		} elseif ( $this->mOldid === 0 ) {
+			$rev = $this->mNewRev->getPrevious();
+			if( $rev ) {
+				$this->mOldid = $rev->getId();
+				$this->mOldRev = $rev;
+			} else {
+				// No previous revision; mark to show as first-version only.
+				$this->mOldid = false;
+				$this->mOldRev = false;
 			}
+		}/* elseif ( $this->mOldid === false ) leave mOldRev 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 );
-			$this->mNewtitle = "<a href='$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 ( $s === false ) {
-				wfDebug( 'Unable to load ' . $this->mNewPage->getPrefixedDBkey . " from old\n" );
+		if( is_null( $this->mOldRev ) ) {
+			return false;
+		}
+
+		if ( $this->mOldRev ) {
+			$this->mOldPage = $this->mOldRev->getTitle();
+
+			$t = $wgLang->timeanddate( $this->mOldRev->getTimestamp(), true );
+			$oldLink = $this->mOldPage->escapeLocalUrl( 'oldid=' . $this->mOldid );
+			$oldEdit = $this->mOldPage->escapeLocalUrl( 'action=edit&oldid=' . $this->mOldid );
+			$this->mOldtitle = "<a href='$oldLink'>" . htmlspecialchars( wfMsg( 'revisionasof', $t ) )
+				. "</a> (<a href='$oldEdit'>" . htmlspecialchars( wfMsg( 'editold' ) ) . "</a>)";
+		}
+
+		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
+			$this->mTextLoaded = 2;
+		}
+
+		if ( !$this->loadRevisionData() ) {
+			return false;
+		}
+		if ( $this->mOldRev ) {
+			// FIXME: permission tests
+			$this->mOldtext = $this->mOldRev->revText();
+			if ( $this->mOldtext === false ) {
 				return false;
 			}
-		} 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
-			);
-			if ( $s === false ) {
-				wfDebug( "Unable to load old_id {$this->mOldid}\n" );
+		}
+		if ( $this->mNewRev ) {
+			$this->mNewtext = $this->mNewRev->revText();
+			if ( $this->mNewtext === false ) {
 				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;
+		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)
@@ -337,7 +655,8 @@ define('USE_ASSERTS', function_exists('assert'));
 
 /**
  * @todo document
- * @package MediaWiki
+ * @private
+ * @addtogroup DifferenceEngine
  */
 class _DiffOp {
 	var $type;
@@ -359,7 +678,8 @@ class _DiffOp {
 
 /**
  * @todo document
- * @package MediaWiki
+ * @private
+ * @addtogroup DifferenceEngine
  */
 class _DiffOp_Copy extends _DiffOp {
 	var $type = 'copy';
@@ -378,7 +698,8 @@ class _DiffOp_Copy extends _DiffOp {
 
 /**
  * @todo document
- * @package MediaWiki
+ * @private
+ * @addtogroup DifferenceEngine
  */
 class _DiffOp_Delete extends _DiffOp {
 	var $type = 'delete';
@@ -395,7 +716,8 @@ class _DiffOp_Delete extends _DiffOp {
 
 /**
  * @todo document
- * @package MediaWiki
+ * @private
+ * @addtogroup DifferenceEngine
  */
 class _DiffOp_Add extends _DiffOp {
 	var $type = 'add';
@@ -412,7 +734,8 @@ class _DiffOp_Add extends _DiffOp {
 
 /**
  * @todo document
- * @package MediaWiki
+ * @private
+ * @addtogroup DifferenceEngine
  */
 class _DiffOp_Change extends _DiffOp {
 	var $type = 'change';
@@ -445,13 +768,20 @@ class _DiffOp_Change extends _DiffOp {
  * closingly, some ideas (subdivision by NCHUNKS > 2, and some optimizations)
  * are my own.
  *
- * @author Geoffrey T. Dairiki
- * @package MediaWiki
- * @access private
+ * Line length limits for robustness added by Tim Starling, 2005-08-31
+ *
+ * @author Geoffrey T. Dairiki, Tim Starling
+ * @private
+ * @addtogroup DifferenceEngine
  */
 class _DiffEngine
 {
+	const MAX_XREF_LENGTH =  10000;
+
 	function diff ($from_lines, $to_lines) {
+		$fname = '_DiffEngine::diff';
+		wfProfileIn( $fname );
+
 		$n_from = sizeof($from_lines);
 		$n_to = sizeof($to_lines);
 
@@ -464,32 +794,34 @@ class _DiffEngine
 
 		// Skip leading common lines.
 		for ($skip = 0; $skip < $n_from && $skip < $n_to; $skip++) {
-			if ($from_lines[$skip] != $to_lines[$skip])
+			if ($from_lines[$skip] !== $to_lines[$skip])
 				break;
 			$this->xchanged[$skip] = $this->ychanged[$skip] = false;
 		}
 		// Skip trailing common lines.
 		$xi = $n_from; $yi = $n_to;
 		for ($endskip = 0; --$xi > $skip && --$yi > $skip; $endskip++) {
-			if ($from_lines[$xi] != $to_lines[$yi])
+			if ($from_lines[$xi] !== $to_lines[$yi])
 				break;
 			$this->xchanged[$xi] = $this->ychanged[$yi] = false;
 		}
 
 		// Ignore lines which do not exist in both files.
-		for ($xi = $skip; $xi < $n_from - $endskip; $xi++)
-			$xhash[$from_lines[$xi]] = 1;
+		for ($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[] = $xi;
@@ -535,9 +867,21 @@ class _DiffEngine
 			elseif ($add)
 				$edits[] = new _DiffOp_Add($add);
 		}
+		wfProfileOut( $fname );
 		return $edits;
 	}
 
+	/**
+	 * Returns the whole line if it's small enough, or the MD5 hash otherwise
+	 */
+	function _line_hash( $line ) {
+		if ( strlen( $line ) > self::MAX_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
@@ -556,102 +900,111 @@ 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, $xlim);
-		}
-
-	if ($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++) {
+		$fname = '_DiffEngine::_diag';
+		wfProfileIn( $fname );
+		$flip = false;
+
+		if ($xlim - $xoff > $ylim - $yoff) {
+			// Things seems faster (I'm not sure I understand why)
+				// when the shortest sequence in X.
+				$flip = true;
+			list ($xoff, $xlim, $yoff, $ylim)
+			= array( $yoff, $ylim, $xoff, $xlim);
+		}
+
+		if ($flip)
+			for ($i = $ylim - 1; $i >= $yoff; $i--)
+				$ymatches[$this->xv[$i]][] = $i;
+		else
+			for ($i = $ylim - 1; $i >= $yoff; $i--)
+				$ymatches[$this->yv[$i]][] = $i;
+
+		$this->lcs = 0;
+		$this->seq[0]= $yoff - 1;
+		$this->in_seq = array();
+		$ymids[0] = array();
+
+		$numer = $xlim - $xoff + $nchunks - 1;
+		$x = $xoff;
+		for ($chunk = 0; $chunk < $nchunks; $chunk++) {
+			wfProfileIn( "$fname-chunk" );
+			if ($chunk > 0)
+				for ($i = 0; $i <= $this->lcs; $i++)
+					$ymids[$i][$chunk-1] = $this->seq[$i];
+
+			$x1 = $xoff + (int)(($numer + ($xlim-$xoff)*$chunk) / $nchunks);
+			for ( ; $x < $x1; $x++) {
 				$line = $flip ? $this->yv[$x] : $this->xv[$x];
-				if (empty($ymatches[$line]))
-			continue;
-		$matches = $ymatches[$line];
+					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);
+		$seps[] = $flip ? array($ylim, $xlim) : array($xlim, $ylim);
 
-	return array($this->lcs, $seps);
+		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]);
+		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;
+		$this->in_seq[$this->seq[$end]] = false;
+		$this->seq[$end] = $ypos;
+		$this->in_seq[$ypos] = 1;
+		wfProfileOut( $fname );
+		return $end;
 	}
 
 	/* Find LCS of two sequences.
@@ -666,48 +1019,51 @@ 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 ($lcs == 0) {
-		// X and Y sequences have no common subsequence:
-		// mark all changed.
-		while ($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 = $pt2;
+		if ($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;
 			}
 		}
+		wfProfileOut( $fname );
 	}
 
 	/* Adjust inserts/deletes of identical lines to join changes
@@ -723,117 +1079,121 @@ 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++;
+		$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[$j]');
+			if ($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++;
+				/*
+				 * 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
- * @package MediaWiki
+ * @private
+ * @addtogroup DifferenceEngine
  */
 class Diff
 {
@@ -864,12 +1224,12 @@ 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 +1253,12 @@ 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 +1303,8 @@ 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()))
@@ -964,13 +1326,15 @@ class Diff
 
 		$lcs = $this->lcs();
 		trigger_error('Diff okay: LCS = '.$lcs, E_USER_NOTICE);
+		wfProfileOut( $fname );
 	}
 }
 
 /**
  * FIXME: bad name.
  * @todo document
- * @package MediaWiki
+ * @private
+ * @addtogroup DifferenceEngine
  */
 class MappedDiff extends Diff
 {
@@ -999,6 +1363,8 @@ 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 +1385,7 @@ class MappedDiff extends Diff
 				$yi += sizeof($closing);
 			}
 		}
+		wfProfileOut( $fname );
 	}
 }
 
@@ -1029,7 +1396,8 @@ class MappedDiff extends Diff
  * It is intended that this class be customized via inheritance,
  * to obtain fancier outputs.
  * @todo document
- * @package MediaWiki
+ * @private
+ * @addtogroup DifferenceEngine
  */
 class DiffFormatter
 {
@@ -1056,6 +1424,8 @@ class DiffFormatter
 	 * @return string The formatted output.
 	 */
 	function format($diff) {
+		$fname = 'DiffFormatter::format';
+		wfProfileIn( $fname );
 
 		$xi = $yi = 1;
 		$block = false;
@@ -1108,10 +1478,14 @@ 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 +1500,7 @@ class DiffFormatter
 				trigger_error('Unknown edit type', E_USER_ERROR);
 		}
 		$this->_end_block();
+		wfProfileOut( $fname );
 	}
 
 	function _start_diff() {
@@ -1187,7 +1562,8 @@ define('NBSP', '&#160;');			// iso-8859-x non-breaking space.
 
 /**
  * @todo document
- * @package MediaWiki
+ * @private
+ * @addtogroup DifferenceEngine
  */
 class _HWLDF_WordAccumulator {
 	function _HWLDF_WordAccumulator () {
@@ -1199,9 +1575,12 @@ class _HWLDF_WordAccumulator {
 
 	function _flushGroup ($new_tag) {
 		if ($this->_group !== '') {
-			if ($this->_tag == 'mark')
-				$this->_line .= '<span class="diffchange">' .
-					htmlspecialchars ( $this->_group ) . '</span>';
+			if ($this->_tag == 'ins')
+				$this->_line .= '<ins class="diffchange">' .
+					htmlspecialchars ( $this->_group ) . '</ins>';
+			elseif ($this->_tag == 'del')
+				$this->_line .= '<del class="diffchange">' .
+					htmlspecialchars ( $this->_group ) . '</del>';
 			else
 				$this->_line .= htmlspecialchars ( $this->_group );
 		}
@@ -1244,57 +1623,96 @@ class _HWLDF_WordAccumulator {
 
 /**
  * @todo document
- * @package MediaWiki
+ * @private
+ * @addtogroup DifferenceEngine
  */
 class WordLevelDiff extends MappedDiff
 {
+	const MAX_LINE_LENGTH = 10000;
+
 	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) {
-		if (!preg_match_all('/ ( [^\S\n]+ | [0-9_A-Za-z\x80-\xff]+ | . ) (?: (?!< \n) [^\S\n])? /xs',
-							implode("\n", $lines),
-							$m)) {
-			return array(array(''), array(''));
+		$fname = 'WordLevelDiff::_split';
+		wfProfileIn( $fname );
+
+		$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 ) > self::MAX_LINE_LENGTH ) {
+				$words[] = $line;
+				$stripped[] = $line;
+			} else {
+				$m = array();
+				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, $m[1] );
+				}
+			}
 		}
-		return array($m[0], $m[1]);
+		wfProfileOut( $fname );
+		return array($words, $stripped);
 	}
 
 	function orig () {
+		$fname = 'WordLevelDiff::orig';
+		wfProfileIn( $fname );
 		$orig = new _HWLDF_WordAccumulator;
 
 		foreach ($this->edits as $edit) {
 			if ($edit->type == 'copy')
 				$orig->addWords($edit->orig);
 			elseif ($edit->orig)
-				$orig->addWords($edit->orig, 'mark');
+				$orig->addWords($edit->orig, 'del');
 		}
-		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 $edit) {
 			if ($edit->type == 'copy')
 				$closing->addWords($edit->closing);
 			elseif ($edit->closing)
-				$closing->addWords($edit->closing, 'mark');
+				$closing->addWords($edit->closing, 'ins');
 		}
-		return $closing->getLines();
+		$lines = $closing->getLines();
+		wfProfileOut( $fname );
+		return $lines;
 	}
 }
 
 /**
  *	Wikipedia Table style diff formatter.
  * @todo document
- * @package MediaWiki
+ * @private
+ * @addtogroup DifferenceEngine
  */
 class TableDiffFormatter extends DiffFormatter
 {
@@ -1304,17 +1722,13 @@ class TableDiffFormatter extends DiffFormatter
 	}
 
 	function _block_header( $xbeg, $xlen, $ybeg, $ylen ) {
-		$l1 = wfMsg( 'lineno', $xbeg );
-		$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";
+		$r = '<tr><td colspan="2" align="left"><strong><!--LINE '.$xbeg."--></strong></td>\n" .
+		  '<td colspan="2" align="left"><strong><!--LINE '.$ybeg."--></strong></td></tr>\n";
 		return $r;
 	}
 
 	function _start_block( $header ) {
-		global $wgOut;
-		$wgOut->addHTML( $header );
+		echo $header;
 	}
 
 	function _end_block() {
@@ -1343,32 +1757,31 @@ class TableDiffFormatter extends DiffFormatter
 	}
 
 	function _added( $lines ) {
-		global $wgOut;
 		foreach ($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>' .
+			echo '<tr>' .
 				$this->contextLine( htmlspecialchars ( $line ) ) .
-				$this->contextLine( htmlspecialchars ( $line ) ) . "</tr>\n" );
+				$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();
@@ -1378,13 +1791,14 @@ class TableDiffFormatter extends DiffFormatter
 
 		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( $aline ) . "</tr>\n";
 		}
 		foreach ($add as $line) {	# If any leftovers
-			$wgOut->addHTML( '<tr>' . $this->emptyLine() .
-				$this->addedLine( $line ) . "</tr>\n" );
+			echo '<tr>' . $this->emptyLine() .
+				$this->addedLine( $line ) . "</tr>\n";
 		}
+		wfProfileOut( $fname );
 	}
 }