From 2a113f6a3a170c8b81338540a20fefd5429c7e9f Mon Sep 17 00:00:00 2001
From: Brion Vibber <brion@users.mediawiki.org>
Date: Thu, 1 Oct 2009 19:32:28 +0000
Subject: [PATCH] fix eol style

---
 includes/diff/DifferenceInterface.php | 2254 ++++++++++++-------------
 1 file changed, 1127 insertions(+), 1127 deletions(-)

diff --git a/includes/diff/DifferenceInterface.php b/includes/diff/DifferenceInterface.php
index 6cfb9717a5..b8478651b5 100644
--- a/includes/diff/DifferenceInterface.php
+++ b/includes/diff/DifferenceInterface.php
@@ -1,1127 +1,1127 @@
-<?php
-/**
- * @defgroup DifferenceEngine DifferenceEngine
- */
- 
-/**
- * Constant to indicate diff cache compatibility.
- * Bump this when changing the diff formatting in a way that
- * fixes important bugs or such to force cached diff views to
- * clear.
- */
-define( 'MW_DIFF_VERSION', '1.11a' );
-
-/**
- * @todo document
- * @ingroup DifferenceEngine
- */
-class DifferenceEngine {
-	/**#@+
-	 * @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?
-	var $mCacheHit = false; // Was the diff fetched from cache?
-	var $htmldiff;
-
-	/**
-	 * Set this to true to add debug info to the HTML output.
-	 * Warning: this may cause RSS readers to spuriously mark articles as "new"
-	 * (bug 20601)
-	 */
-	var $enableDebugComment = false;
-
-	// If true, line X is not displayed when X is 1, for example to increase
-	// readability and conserve space with many small diffs.
-	protected $mReducedLineNumbers = false;
-
-	protected $unhide = false;
-	/**#@-*/
-
-	/**
-	 * 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)
-	 * @param $refreshCache boolean If set, refreshes the diff cache
-	 * @param $htmldiff boolean If set, output using HTMLDiff instead of raw wikicode diff
-	 * @param $unhide boolean If set, allow viewing deleted revs
-	 */
-	function __construct( $titleObj = null, $old = 0, $new = 0, $rcid = 0,
-		$refreshCache = false, $htmldiff = false, $unhide = false )
-	{
-		if ( $titleObj ) {
-			$this->mTitle = $titleObj;
-		} else {
-			global $wgTitle;
-			$this->mTitle = $wgTitle;
-		}
-		wfDebug("DifferenceEngine old '$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);
-			$this->mOldid = $this->mTitle->getPreviousRevisionID( $this->mNewid );
-		} elseif ( 'next' === $new ) {
-			# Show diff between revision $old and the next one.
-			# Get next one from DB.
-			$this->mOldid = intval($old);
-			$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".
-				$this->mNewid = 0;
-			}
-		} else {
-			$this->mOldid = intval($old);
-			$this->mNewid = intval($new);
-			wfRunHooks( 'NewDifferenceEngine', array(&$titleObj, &$this->mOldid, &$this->mNewid, $old, $new) ); 
-		}
-		$this->mRcidMarkPatrolled = intval($rcid);  # force it to be an integer
-		$this->mRefreshCache = $refreshCache;
-		$this->htmldiff = $htmldiff;
-		$this->unhide = $unhide;
-	}
-
-	function setReducedLineNumbers( $value = true ) {
-		$this->mReducedLineNumbers = $value;
-	}
-
-	function getTitle() {
-		return $this->mTitle;
-	}
-	
-	function wasCacheHit() {
-		return $this->mCacheHit;
-	}
-	
-	function getOldid() {
-		return $this->mOldid;
-	}
-	
-	function getNewid() {
-		return $this->mNewid;
-	}
-
-	function showDiffPage( $diffOnly = false ) {
-		global $wgUser, $wgOut, $wgUseExternalEditor, $wgUseRCPatrol, $wgEnableHtmlDiff;
-		wfProfileIn( __METHOD__ );
-
-
-		# If external diffs are enabled both globally and for the user,
-		# we'll use the application/x-external-editor interface to call
-		# an external diff tool like kompare, kdiff3, etc.
-		if($wgUseExternalEditor && $wgUser->getOption('externaldiff')) {
-			global $wgInputEncoding,$wgServer,$wgScript,$wgLang;
-			$wgOut->disable();
-			header ( "Content-type: application/x-external-editor; charset=".$wgInputEncoding );
-			$url1=$this->mTitle->getFullURL( array(
-				'action' => 'raw',
-				'oldid' => $this->mOldid
-			) );
-			$url2=$this->mTitle->getFullURL( array(
-				'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();
-			$d = wfMsgExt( 'missingarticle-diff', array( 'escape' ), $this->mOldid, $this->mNewid );
-			$wgOut->setPagetitle( wfMsg( 'errorpagetitle' ) );
-			$wgOut->addWikiMsg( 'missing-article', "<nowiki>$t</nowiki>", $d );
-			wfProfileOut( __METHOD__ );
-			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( __METHOD__ );
-			return;
-		}
-
-		$wgOut->suppressQuickbar();
-
-		$oldTitle = $this->mOldPage->getPrefixedText();
-		$newTitle = $this->mNewPage->getPrefixedText();
-		if( $oldTitle == $newTitle ) {
-			$wgOut->setPageTitle( $newTitle );
-		} else {
-			$wgOut->setPageTitle( $oldTitle . ', ' . $newTitle );
-		}
-		$wgOut->setSubtitle( wfMsgExt( 'difference', array( 'parseinline' ) ) );
-		$wgOut->setRobotPolicy( 'noindex,nofollow' );
-
-		if ( !$this->mOldPage->userCanRead() || !$this->mNewPage->userCanRead() ) {
-			$wgOut->loginToUse();
-			$wgOut->output();
-			$wgOut->disable();
-			wfProfileOut( __METHOD__ );
-			return;
-		}
-
-		$sk = $wgUser->getSkin();
-
-		// Check if page is editable
-		$editable = $this->mNewRev->getTitle()->userCan( 'edit' );
-		if ( $editable && $this->mNewRev->isCurrent() && $wgUser->isAllowed( 'rollback' ) ) {
-			$rollback = '&nbsp;&nbsp;&nbsp;' . $sk->generateRollback( $this->mNewRev );
-		} else {
-			$rollback = '';
-		}
-
-		// Prepare a change patrol link, if applicable
-		if( $wgUseRCPatrol && $this->mTitle->userCan('patrol') ) {
-			// If we've been given an explicit change identifier, use it; saves time
-			if( $this->mRcidMarkPatrolled ) {
-				$rcid = $this->mRcidMarkPatrolled;
-				$rc = RecentChange::newFromId( $rcid );
-				// Already patrolled?
-				$rcid = is_object($rc) && !$rc->getAttribute('rc_patrolled') ? $rcid : 0;
-			} else {
-				// Look for an unpatrolled change corresponding to this diff
-				$db = wfGetDB( DB_SLAVE );
-				$change = RecentChange::newFromConds(
-					array(
-					// Redundant user,timestamp condition so we can use the existing index
-						'rc_user_text'  => $this->mNewRev->getRawUserText(),
-						'rc_timestamp'  => $db->timestamp( $this->mNewRev->getTimestamp() ),
-						'rc_this_oldid' => $this->mNewid,
-						'rc_last_oldid' => $this->mOldid,
-						'rc_patrolled'  => 0
-					),
-					__METHOD__
-				);
-				if( $change instanceof RecentChange ) {
-					$rcid = $change->mAttribs['rc_id'];
-					$this->mRcidMarkPatrolled = $rcid;
-				} else {
-					// None found
-					$rcid = 0;
-				}
-			}
-			// Build the link
-			if( $rcid ) {
-				$patrol = ' <span class="patrollink">[' . $sk->link(
-					$this->mTitle, 
-					wfMsgHtml( 'markaspatrolleddiff' ),
-					array(),
-					array(
-						'action' => 'markpatrolled',
-						'rcid' => $rcid
-					),
-					array(
-						'known',
-						'noclasses'
-					)
-				) . ']</span>';
-			} else {
-				$patrol = '';
-			}
-		} else {
-			$patrol = '';
-		}
-
-		# Carry over 'diffonly' param via navigation links
-		if( $diffOnly != $wgUser->getBoolOption('diffonly') ) {
-			$query['diffonly'] = $diffOnly;
-		}
-
-		$htmldiffarg = $this->htmlDiffArgument();
-
-		if( $htmldiffarg ) {
-			$query['htmldiff'] = $htmldiffarg['htmldiff'];
-		}
-
-		# Make "previous revision link"
-		$query['diff'] = 'prev';
-		$query['oldid'] = $this->mOldid;
-
-		$prevlink = $sk->link(
-			$this->mTitle,
-			wfMsgHtml( 'previousdiff' ),
-			array(
-				'id' => 'differences-prevlink'
-			),
-			$query,
-			array(
-				'known',
-				'noclasses'
-			)
-		);
-		# Make "next revision link"
-		$query['diff'] = 'next';
-		$query['oldid'] = $this->mNewid;
-
-		if( $this->mNewRev->isCurrent() ) {
-			$nextlink = '&nbsp;';
-		} else {
-			$nextlink = $sk->link(
-				$this->mTitle,
-				wfMsgHtml( 'nextdiff' ),
-				array(
-					'id' => 'differences-nextlink'
-				),
-				$query,
-				array(
-					'known',
-					'noclasses'
-				)
-			);
-		}
-
-		$oldminor = '';
-		$newminor = '';
-
-		if( $this->mOldRev->isMinor() ) {
-			$oldminor = ChangesList::flag( 'minor' );
-		}
-		if( $this->mNewRev->isMinor() ) {
-			$newminor = ChangesList::flag( 'minor' );
-		}
-
-		$rdel = ''; $ldel = '';
-		if( $wgUser->isAllowed( 'deletedhistory' ) ) {
-			// Don't show useless link to people who cannot hide revisions
-			if( $this->mOldRev->getVisibility() || $wgUser->isAllowed( 'deleterevision' ) ) {
-				if( !$this->mOldRev->userCan( Revision::DELETED_RESTRICTED ) ) {
-					// If revision was hidden from sysops
-					$ldel = Xml::tags( 'span', array( 'class' => 'mw-revdelundel-link' ),
-						'(' . wfMsgHtml( 'rev-delundel' ) . ')' );
-				} else {
-					$query = array( 
-						'type' => 'revision',
-						'target' => $this->mOldRev->mTitle->getPrefixedDbkey(),
-						'ids' => $this->mOldRev->getId()
-					);
-					$ldel = $sk->revDeleteLink( $query, $this->mOldRev->isDeleted( Revision::DELETED_RESTRICTED ) );
-				}
-				$ldel = "&nbsp;&nbsp;&nbsp;$ldel ";
-			}
-			// Don't show useless link to people who cannot hide revisions
-			if( $this->mNewRev->getVisibility() || $wgUser->isAllowed( 'deleterevision' ) ) {
-				if( !$this->mNewRev->userCan( Revision::DELETED_RESTRICTED ) ) {
-					// If revision was hidden from sysops
-					$rdel = Xml::tags( 'span', array( 'class'=>'mw-revdelundel-link' ), '('.wfMsgHtml( 'rev-delundel' ).')' );
-				} else {
-					$query = array( 
-						'type' => 'revision',
-						'target' =>  $this->mNewRev->mTitle->getPrefixedDbkey(),
-						'ids' => $this->mNewRev->getId()
-					);
-					$rdel = $sk->revDeleteLink( $query, $this->mNewRev->isDeleted( Revision::DELETED_RESTRICTED ) );
-				}
-				$rdel = "&nbsp;&nbsp;&nbsp;$rdel ";
-			}
-		}
-
-		$oldHeader = '<div id="mw-diff-otitle1"><strong>'.$this->mOldtitle.'</strong></div>' .
-			'<div id="mw-diff-otitle2">' . $sk->revUserTools( $this->mOldRev, !$this->unhide ) . "</div>" .
-			'<div id="mw-diff-otitle3">' . $oldminor . $sk->revComment( $this->mOldRev, !$diffOnly, !$this->unhide ).$ldel."</div>" .
-			'<div id="mw-diff-otitle4">' . $prevlink .'</div>';
-		$newHeader = '<div id="mw-diff-ntitle1"><strong>'.$this->mNewtitle.'</strong></div>' .
-			'<div id="mw-diff-ntitle2">' . $sk->revUserTools( $this->mNewRev, !$this->unhide ) . " $rollback</div>" .
-			'<div id="mw-diff-ntitle3">' . $newminor . $sk->revComment( $this->mNewRev, !$diffOnly, !$this->unhide ).$rdel."</div>" .
-			'<div id="mw-diff-ntitle4">' . $nextlink . $patrol . '</div>';
-
-		# Check if this user can see the revisions
-		$allowed = $this->mOldRev->userCan(Revision::DELETED_TEXT)
-			&& $this->mNewRev->userCan(Revision::DELETED_TEXT);
-		# Check if one of the revisions is deleted/suppressed
-		$deleted = $suppressed = false;
-		if( $this->mOldRev->isDeleted(Revision::DELETED_TEXT) ) {
-			$deleted = true; // old revisions text is hidden
-			if( $this->mOldRev->isDeleted(Revision::DELETED_RESTRICTED) )
-				$suppressed = true; // also suppressed
-		}
-		if( $this->mNewRev->isDeleted(Revision::DELETED_TEXT) ) {
-			$deleted = true; // new revisions text is hidden
-			if( $this->mNewRev->isDeleted(Revision::DELETED_RESTRICTED) )
-				$suppressed = true; // also suppressed
-		}
-		# Output the diff if allowed...
-		if( $deleted && (!$this->unhide || !$allowed) ) {
-			$this->showDiffStyle();
-			$multi = $this->getMultiNotice();
-			$wgOut->addHTML( $this->addHeader( '', $oldHeader, $newHeader, $multi ) );
-			if( !$allowed ) {
-				# Give explanation for why revision is not visible
-				$wgOut->wrapWikiMsg( "<div class='mw-warning plainlinks'>\n$1</div>\n",
-					array( 'rev-deleted-no-diff' ) );
-			} else {
-				# Give explanation and add a link to view the diff...
-				$link = $this->mTitle->getFullUrl( array(
-					'diff' => $this->mNewid,
-					'oldid' => $this->mOldid,
-					'unhide' => 1
-				) );
-				$msg = $suppressed ? 'rev-suppressed-unhide-diff' : 'rev-deleted-unhide-diff';
-				$wgOut->wrapWikiMsg( "<div class='mw-warning plainlinks'>\n$1</div>\n", array( $msg, $link ) );
-			}
-		} else if( $wgEnableHtmlDiff && $this->htmldiff ) {
-			$multi = $this->getMultiNotice();
-			$wgOut->addHTML( '<div class="diff-switchtype">' . $sk->link(
-				$this->mTitle,
-				wfMsgHtml( 'wikicodecomparison' ),
-				array(
-					'id' => 'differences-switchtype'
-				),
-				array(
-					'diff' => $this->mNewid,
-					'oldid' => $this->mOldid,
-					'htmldiff' => 0
-				),
-				array(
-					'known',
-					'noclasses'
-				)
-			) . '</div>');
-			$wgOut->addHTML( $this->addHeader( '', $oldHeader, $newHeader, $multi ) );
-			$this->renderHtmlDiff();
-		} else {
-			if( $wgEnableHtmlDiff ) {
-				$wgOut->addHTML( '<div class="diff-switchtype">' . $sk->link(
-					$this->mTitle,
-					wfMsgHtml( 'visualcomparison' ),
-					array(
-						'id' => 'differences-switchtype'
-					),
-					array(
-						'diff' => $this->mNewid,
-						'oldid' => $this->mOldid,
-						'htmldiff' => 1
-					),
-					array(
-						'known',
-						'noclasses'
-					)
-				) . '</div>');
-			}
-			$this->showDiff( $oldHeader, $newHeader );
-			if( !$diffOnly ) {
-				$this->renderNewRevision();
-			}
-		}
-		wfProfileOut( __METHOD__ );
-	}
-
-	/**
-	 * Show the new revision of the page.
-	 */
-	function renderNewRevision() {
-		global $wgOut, $wgUser;
-		wfProfileIn( __METHOD__ );
-
-		$wgOut->addHTML( "<hr /><h2>{$this->mPagetitle}</h2>\n" );
-		# Add deleted rev tag if needed
-		if( !$this->mNewRev->userCan(Revision::DELETED_TEXT) ) {
-			$wgOut->wrapWikiMsg( "<div class='mw-warning plainlinks'>\n$1</div>\n", 'rev-deleted-text-permission' );
-		} else if( $this->mNewRev->isDeleted(Revision::DELETED_TEXT) ) {
-			$wgOut->wrapWikiMsg( "<div class='mw-warning plainlinks'>\n$1</div>\n", 'rev-deleted-text-view' );
-		}
-
-		if( !$this->mNewRev->isCurrent() ) {
-			$oldEditSectionSetting = $wgOut->parserOptions()->setEditSection( false );
-		}
-
-		$this->loadNewText();
-		if( is_object( $this->mNewRev ) ) {
-			$wgOut->setRevisionId( $this->mNewRev->getId() );
-		}
-
-		if( $this->mTitle->isCssJsSubpage() || $this->mTitle->isCssOrJsPage() ) {
-			// Stolen from Article::view --AG 2007-10-11
-			// Give hooks a chance to customise the output
-			if( wfRunHooks( 'ShowRawCssJs', array( $this->mNewtext, $this->mTitle, $wgOut ) ) ) {
-				// Wrap the whole lot in a <pre> and don't parse
-				$m = array();
-				preg_match( '!\.(css|js)$!u', $this->mTitle->getText(), $m );
-				$wgOut->addHTML( "<pre class=\"mw-code mw-{$m[1]}\" dir=\"ltr\">\n" );
-				$wgOut->addHTML( htmlspecialchars( $this->mNewtext ) );
-				$wgOut->addHTML( "\n</pre>\n" );
-			}
-		} else {
-			$wgOut->addWikiTextTidy( $this->mNewtext );
-		}
-
-		if( is_object( $this->mNewRev ) && !$this->mNewRev->isCurrent() ) {
-			$wgOut->parserOptions()->setEditSection( $oldEditSectionSetting );
-		}
-		# Add redundant patrol link on bottom...
-		if( $this->mRcidMarkPatrolled && $this->mTitle->quickUserCan('patrol') ) {
-			$sk = $wgUser->getSkin();
-			$wgOut->addHTML(
-				"<div class='patrollink'>[" . $sk->link(
-					$this->mTitle,
-					wfMsgHtml( 'markaspatrolleddiff' ),
-					array(),
-					array(
-						'action' => 'markpatrolled',
-						'rcid' => $this->mRcidMarkPatrolled
-					)
-				) . ']</div>'
-			 );
-		}
-
-		wfProfileOut( __METHOD__ );
-	}
-
-
-	function renderHtmlDiff() {
-		global $wgOut, $wgParser, $wgDebugComments;
-		wfProfileIn( __METHOD__ );
-
-		$this->showDiffStyle();
-
-		$wgOut->addHTML( '<h2>'.wfMsgHtml( 'visual-comparison' )."</h2>\n" );
-		#add deleted rev tag if needed
-		if( !$this->mNewRev->userCan(Revision::DELETED_TEXT) ) {
-			$wgOut->wrapWikiMsg( "<div class='mw-warning plainlinks'>\n$1</div>\n", 'rev-deleted-text-permission' );
-		} else if( $this->mNewRev->isDeleted(Revision::DELETED_TEXT) ) {
-			$wgOut->wrapWikiMsg( "<div class='mw-warning plainlinks'>\n$1</div>\n", 'rev-deleted-text-view' );
-		}
-
-		if( !$this->mNewRev->isCurrent() ) {
-			$oldEditSectionSetting = $wgOut->parserOptions()->setEditSection( false );
-		}
-
-		$this->loadText();
-
-		// Old revision
-		if( is_object( $this->mOldRev ) ) {
-			$wgOut->setRevisionId( $this->mOldRev->getId() );
-		}
-
-		$popts = $wgOut->parserOptions();
-		$oldTidy = $popts->setTidy( true );
-		$popts->setEditSection( false );
-
-		$parserOutput = $wgParser->parse( $this->mOldtext, $this->getTitle(), $popts, true, true, $wgOut->getRevisionId() );
-		$popts->setTidy( $oldTidy );
-
-		//only for new?
-		//$wgOut->addParserOutputNoText( $parserOutput );
-		$oldHtml = $parserOutput->getText();
-		wfRunHooks( 'OutputPageBeforeHTML', array( &$wgOut, &$oldHtml ) );
-
-		// New revision
-		if( is_object( $this->mNewRev ) ) {
-			$wgOut->setRevisionId( $this->mNewRev->getId() );
-		}
-
-		$popts = $wgOut->parserOptions();
-		$oldTidy = $popts->setTidy( true );
-
-		$parserOutput = $wgParser->parse( $this->mNewtext, $this->getTitle(), $popts, true, true, $wgOut->getRevisionId() );
-		$popts->setTidy( $oldTidy );
-
-		$wgOut->addParserOutputNoText( $parserOutput );
-		$newHtml = $parserOutput->getText();
-		wfRunHooks( 'OutputPageBeforeHTML', array( &$wgOut, &$newHtml ) );
-
-		unset($parserOutput, $popts);
-
-		$differ = new HTMLDiffer(new DelegatingContentHandler($wgOut));
-		$differ->htmlDiff($oldHtml, $newHtml);
-		if ( $wgDebugComments ) {
-			$wgOut->addHTML( "\n<!-- HtmlDiff Debug Output:\n" . HTMLDiffer::getDebugOutput() . " End Debug -->" );
-		}
-
-		wfProfileOut( __METHOD__ );
-	}
-
-	/**
-	 * Show the first revision of an article. Uses normal diff headers in
-	 * contrast to normal "old revision" display style.
-	 */
-	function showFirstRevision() {
-		global $wgOut, $wgUser;
-		wfProfileIn( __METHOD__ );
-
-		# Get article text from the DB
-		#
-		if ( ! $this->loadNewText() ) {
-			$t = $this->mTitle->getPrefixedText();
-			$d = wfMsgExt( 'missingarticle-diff', array( 'escape' ), $this->mOldid, $this->mNewid );
-			$wgOut->setPagetitle( wfMsg( 'errorpagetitle' ) );
-			$wgOut->addWikiMsg( 'missing-article', "<nowiki>$t</nowiki>", $d );
-			wfProfileOut( __METHOD__ );
-			return;
-		}
-		if ( $this->mNewRev->isCurrent() ) {
-			$wgOut->setArticleFlag( true );
-		}
-
-		# Check if user is allowed to look at this page. If not, bail out.
-		#
-		if ( !$this->mTitle->userCanRead() ) {
-			$wgOut->loginToUse();
-			$wgOut->output();
-			wfProfileOut( __METHOD__ );
-			throw new MWException("Permission Error: you do not have access to view this page");
-		}
-
-		# Prepare the header box
-		#
-		$sk = $wgUser->getSkin();
-
-		$next = $this->mTitle->getNextRevisionID( $this->mNewid );
-		if( !$next ) {
-			$nextlink = '';
-		} else {
-			$nextlink = '<br/>' . $sk->link(
-				$this->mTitle,
-				wfMsgHtml( 'nextdiff' ),
-				array(
-					'id' => 'differences-nextlink'
-				),
-				array(
-					'diff' => 'next',
-					'oldid' => $this->mNewid,
-					$this->htmlDiffArgument()
-				),
-				array(
-					'known',
-					'noclasses'
-				)
-			);
-		}
-		$header = "<div class=\"firstrevisionheader\" style=\"text-align: center\">" .
-			$sk->revUserTools( $this->mNewRev ) . "<br/>" . $sk->revComment( $this->mNewRev ) . $nextlink . "</div>\n";
-
-		$wgOut->addHTML( $header );
-
-		$wgOut->setSubtitle( wfMsgExt( 'difference', array( 'parseinline' ) ) );
-		$wgOut->setRobotPolicy( 'noindex,nofollow' );
-
-		wfProfileOut( __METHOD__ );
-	}
-
-	function htmlDiffArgument(){
-		global $wgEnableHtmlDiff;
-		if($wgEnableHtmlDiff){
-			if($this->htmldiff){
-				return array( 'htmldiff' => 1 );
-			}else{
-				return array( 'htmldiff' => 0 );
-			}
-		}else{
-			return array();
-		}
-	}
-
-	/**
-	 * 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->addWikiMsg( 'missing-article', "<nowiki>(fixme, bug)</nowiki>", '' );
-			return false;
-		} else {
-			$this->showDiffStyle();
-			$wgOut->addHTML( $diff );
-			return true;
-		}
-	}
-
-	/**
-	 * Add style sheets and supporting JS for diff display.
-	 */
-	function showDiffStyle() {
-		global $wgStylePath, $wgStyleVersion, $wgOut;
-		$wgOut->addStyle( 'common/diff.css' );
-
-		// JS is needed to detect old versions of Mozilla to work around an annoyance bug.
-		$wgOut->addScript( "<script type=\"text/javascript\" src=\"$wgStylePath/common/diff.js?$wgStyleVersion\"></script>" );
-	}
-
-	/**
-	 * Get complete diff table, including header
-	 *
-	 * @param Title $otitle Old title
-	 * @param Title $ntitle New title
-	 * @return mixed
-	 */
-	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
-	 *
-	 * @return mixed
-	 */
-	function getDiffBody() {
-		global $wgMemc;
-		wfProfileIn( __METHOD__ );
-		$this->mCacheHit = true;
-		// Check if the diff should be hidden from this user
-		if ( !$this->loadRevisionData() )
-			return '';
-		if ( $this->mOldRev && !$this->mOldRev->userCan(Revision::DELETED_TEXT) ) {
-			return '';
-		} else if ( $this->mNewRev && !$this->mNewRev->userCan(Revision::DELETED_TEXT) ) {
-			return '';
-		} else if ( $this->mOldRev && $this->mNewRev && $this->mOldRev->getID() == $this->mNewRev->getID() ) {
-			return '';
-		}
-		// Cacheable?
-		$key = false;
-		if ( $this->mOldid && $this->mNewid ) {
-			$key = wfMemcKey( 'diff', 'version', MW_DIFF_VERSION, 'oldid', $this->mOldid, 'newid', $this->mNewid );
-			// Try cache
-			if ( !$this->mRefreshCache ) {
-				$difftext = $wgMemc->get( $key );
-				if ( $difftext ) {
-					wfIncrStats( 'diff_cache_hit' );
-					$difftext = $this->localiseLineNumbers( $difftext );
-					$difftext .= "\n<!-- diff cache key $key -->\n";
-					wfProfileOut( __METHOD__ );
-					return $difftext;
-				}
-			} // don't try to load but save the result
-		}
-		$this->mCacheHit = false;
-
-		// Loadtext is permission safe, this just clears out the diff
-		if ( !$this->loadText() ) {
-			wfProfileOut( __METHOD__ );
-			return false;
-		}
-
-		$difftext = $this->generateDiffBody( $this->mOldtext, $this->mNewtext );
-
-		// Save to cache for 7 days
-		if ( !wfRunHooks( 'AbortDiffCache', array( &$this ) ) ) {
-			wfIncrStats( 'diff_uncacheable' );
-		} else 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( __METHOD__ );
-		return $difftext;
-	}
-
-	/**
-	 * Make sure the proper modules are loaded before we try to
-	 * make the diff
-	 */
-	private function initDiffEngines() {
-		global $wgExternalDiffEngine;
-		if ( $wgExternalDiffEngine == 'wikidiff' && !function_exists( 'wikidiff_do_diff' ) ) {
-			wfProfileIn( __METHOD__ . '-php_wikidiff.so' );
-			wfSuppressWarnings();
-			dl( 'php_wikidiff.so' );
-			wfRestoreWarnings();
-			wfProfileOut( __METHOD__ . '-php_wikidiff.so' );
-		}
-		else if ( $wgExternalDiffEngine == 'wikidiff2' && !function_exists( 'wikidiff2_do_diff' ) ) {
-			wfProfileIn( __METHOD__ . '-php_wikidiff2.so' );
-			wfSuppressWarnings();
-			dl( 'php_wikidiff2.so' );
-			wfRestoreWarnings();
-			wfProfileOut( __METHOD__ . '-php_wikidiff2.so' );
-		}
-	}
-
-	/**
-	 * Generate a diff, no caching
-	 * $otext and $ntext must be already segmented
-	 */
-	function generateDiffBody( $otext, $ntext ) {
-		global $wgExternalDiffEngine, $wgContLang;
-
-		$otext = str_replace( "\r\n", "\n", $otext );
-		$ntext = str_replace( "\r\n", "\n", $ntext );
-
-		$this->initDiffEngines();
-
-		if ( $wgExternalDiffEngine == 'wikidiff' && function_exists( 'wikidiff_do_diff' ) ) {
-			# For historical reasons, external diff engine expects
-			# input text to be HTML-escaped already
-			$otext = htmlspecialchars ( $wgContLang->segmentForDiff( $otext ) );
-			$ntext = htmlspecialchars ( $wgContLang->segmentForDiff( $ntext ) );
-			return $wgContLang->unsegementForDiff( wikidiff_do_diff( $otext, $ntext, 2 ) ) .
-			$this->debug( 'wikidiff1' );
-		}
-
-		if ( $wgExternalDiffEngine == 'wikidiff2' && function_exists( 'wikidiff2_do_diff' ) ) {
-			# Better external diff engine, the 2 may some day be dropped
-			# This one does the escaping and segmenting itself
-			wfProfileIn( 'wikidiff2_do_diff' );
-			$text = wikidiff2_do_diff( $otext, $ntext, 2 );
-			$text .= $this->debug( 'wikidiff2' );
-			wfProfileOut( 'wikidiff2_do_diff' );
-			return $text;
-		}
-		if ( $wgExternalDiffEngine != 'wikidiff3' && $wgExternalDiffEngine !== false ) {
-			# Diff via the shell
-			global $wgTmpDirectory;
-			$tempName1 = tempnam( $wgTmpDirectory, 'diff_' );
-			$tempName2 = tempnam( $wgTmpDirectory, 'diff_' );
-
-			$tempFile1 = fopen( $tempName1, "w" );
-			if ( !$tempFile1 ) {
-				wfProfileOut( __METHOD__ );
-				return false;
-			}
-			$tempFile2 = fopen( $tempName2, "w" );
-			if ( !$tempFile2 ) {
-				wfProfileOut( __METHOD__ );
-				return false;
-			}
-			fwrite( $tempFile1, $otext );
-			fwrite( $tempFile2, $ntext );
-			fclose( $tempFile1 );
-			fclose( $tempFile2 );
-			$cmd = wfEscapeShellArg( $wgExternalDiffEngine, $tempName1, $tempName2 );
-			wfProfileIn( __METHOD__ . "-shellexec" );
-			$difftext = wfShellExec( $cmd );
-			$difftext .= $this->debug( "external $wgExternalDiffEngine" );
-			wfProfileOut( __METHOD__ . "-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 ) ) .
-		$this->debug();
-	}
-
-	/**
-	 * Generate a debug comment indicating diff generating time,
-	 * server node, and generator backend.
-	 */
-	protected function debug( $generator="internal" ) {
-		global $wgShowHostnames;
-		if ( !$this->enableDebugComment ) {
-			return '';
-		}
-		$data = array( $generator );
-		if( $wgShowHostnames ) {
-			$data[] = wfHostname();
-		}
-		$data[] = wfTimestamp( TS_DB );
-		return "<!-- diff generator: " .
-		implode( " ",
-		array_map(
-					"htmlspecialchars",
-		$data ) ) .
-			" -->\n";
-	}
-
-	/**
-	 * 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;
-		if ( $matches[1] === '1' && $this->mReducedLineNumbers ) return '';
-		return wfMsgExt( 'lineno', 'escape', $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 );
-	}
-
-
-	/**
-	 * Add the header to a diff body
-	 */
-	static function addHeader( $diff, $otitle, $ntitle, $multi = '' ) {
-		$colspan = 1;
-		$header = "<table class='diff'>";
-		if( $diff ) { // Safari/Chrome show broken output if cols not used
-			$header .= "
-			<col class='diff-marker' />
-			<col class='diff-content' />
-			<col class='diff-marker' />
-			<col class='diff-content' />";
-			$colspan = 2;
-		}
-		$header .= "
-		<tr valign='top'>
-		<td colspan='$colspan' class='diff-otitle'>{$otitle}</td>
-		<td colspan='$colspan' class='diff-ntitle'>{$ntitle}</td>
-		</tr>";
-
-		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;
-		$this->mRevisionsLoaded = true;
-	}
-
-	/**
-	 * 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, $wgUser;
-		if ( $this->mRevisionsLoaded ) {
-			return true;
-		} else {
-			// Whether it succeeds or fails, we don't want to try again
-			$this->mRevisionsLoaded = true;
-		}
-
-		// Load the new revision object
-		$this->mNewRev = $this->mNewid
-			? Revision::newFromId( $this->mNewid )
-			: Revision::newFromTitle( $this->mTitle );
-		if( !$this->mNewRev instanceof Revision )
-			return false;
-
-		// Update the new revision ID in case it was 0 (makes life easier doing UI stuff)
-		$this->mNewid = $this->mNewRev->getId();
-
-		// Check if page is editable
-		$editable = $this->mNewRev->getTitle()->userCan( 'edit' );
-
-		// Set assorted variables
-		$timestamp = $wgLang->timeanddate( $this->mNewRev->getTimestamp(), true );
-		$dateofrev = $wgLang->date( $this->mNewRev->getTimestamp(), true );
-		$timeofrev = $wgLang->time( $this->mNewRev->getTimestamp(), true );
-		$this->mNewPage = $this->mNewRev->getTitle();
-		if( $this->mNewRev->isCurrent() ) {
-			$newLink = $this->mNewPage->escapeLocalUrl( array(
-				'oldid' => $this->mNewid
-			) );
-			$this->mPagetitle = htmlspecialchars( wfMsg(
-				'currentrev-asof',
-				$timestamp,
-				$dateofrev,
-				$timeofrev
-			) );
-			$newEdit = $this->mNewPage->escapeLocalUrl( array(
-				'action' => 'edit'
-			) );
-
-			$this->mNewtitle = "<a href='$newLink'>{$this->mPagetitle}</a>";
-			$this->mNewtitle .= " (<a href='$newEdit'>" . wfMsgHtml( $editable ? 'editold' : 'viewsourceold' ) . "</a>)";
-		} else {
-			$newLink = $this->mNewPage->escapeLocalUrl( array(
-				'oldid' => $this->mNewid
-			) );
-			$newEdit = $this->mNewPage->escapeLocalUrl( array(
-				'action' => 'edit',
-				'oldid' => $this->mNewid
-			) );
-			$this->mPagetitle = htmlspecialchars( wfMsg(
-				'revisionasof',
-				$timestamp,
-				$dateofrev,
-				$timeofrev
-			) );
-
-			$this->mNewtitle = "<a href='$newLink'>{$this->mPagetitle}</a>";
-			$this->mNewtitle .= " (<a href='$newEdit'>" . wfMsgHtml( $editable ? 'editold' : 'viewsourceold' ) . "</a>)";
-		}
-		if( !$this->mNewRev->userCan(Revision::DELETED_TEXT) ) {
-			$this->mNewtitle = "<span class='history-deleted'>{$this->mPagetitle}</span>";
-		} else if ( $this->mNewRev->isDeleted(Revision::DELETED_TEXT) ) {
-			$this->mNewtitle = "<span class='history-deleted'>{$this->mNewtitle}</span>";
-		}
-
-		// 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; */
-
-		if( is_null( $this->mOldRev ) ) {
-			return false;
-		}
-
-		if ( $this->mOldRev ) {
-			$this->mOldPage = $this->mOldRev->getTitle();
-
-			$t = $wgLang->timeanddate( $this->mOldRev->getTimestamp(), true );
-			$dateofrev = $wgLang->date( $this->mOldRev->getTimestamp(), true );
-			$timeofrev = $wgLang->time( $this->mOldRev->getTimestamp(), true );
-			$oldLink = $this->mOldPage->escapeLocalUrl( array(
-				'oldid' => $this->mOldid
-			) );
-			$oldEdit = $this->mOldPage->escapeLocalUrl( array(
-				'action' => 'edit',
-				'oldid' => $this->mOldid
-			) );
-			$this->mOldPagetitle = htmlspecialchars( wfMsg( 'revisionasof', $t, $dateofrev, $timeofrev ) );
-
-			$this->mOldtitle = "<a href='$oldLink'>{$this->mOldPagetitle}</a>"
-			. " (<a href='$oldEdit'>" . wfMsgHtml( $editable ? 'editold' : 'viewsourceold' ) . "</a>)";
-			// Add an "undo" link
-			$newUndo = $this->mNewPage->escapeLocalUrl( array(
-				'action' => 'edit',
-				'undoafter' => $this->mOldid,
-				'undo' => $this->mNewid
-			) );
-			$htmlLink = htmlspecialchars( wfMsg( 'editundo' ) );
-			$htmlTitle = $wgUser->getSkin()->tooltip( 'undo' );
-			if( $editable && !$this->mOldRev->isDeleted( Revision::DELETED_TEXT ) && !$this->mNewRev->isDeleted( Revision::DELETED_TEXT ) ) {
-				$this->mNewtitle .= " (<a href='$newUndo' $htmlTitle>" . $htmlLink . "</a>)";
-			}
-
-			if( !$this->mOldRev->userCan( Revision::DELETED_TEXT ) ) {
-				$this->mOldtitle = '<span class="history-deleted">' . $this->mOldPagetitle . '</span>';
-			} else if( $this->mOldRev->isDeleted( Revision::DELETED_TEXT ) ) {
-				$this->mOldtitle = '<span class="history-deleted">' . $this->mOldtitle . '</span>';
-			}
-		}
-
-		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 ) {
-			$this->mOldtext = $this->mOldRev->getText( Revision::FOR_THIS_USER );
-			if ( $this->mOldtext === false ) {
-				return false;
-			}
-		}
-		if ( $this->mNewRev ) {
-			$this->mNewtext = $this->mNewRev->getText( Revision::FOR_THIS_USER );
-			if ( $this->mNewtext === false ) {
-				return false;
-			}
-		}
-		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( Revision::FOR_THIS_USER );
-		return true;
-	}
-}
+<?php
+/**
+ * @defgroup DifferenceEngine DifferenceEngine
+ */
+ 
+/**
+ * Constant to indicate diff cache compatibility.
+ * Bump this when changing the diff formatting in a way that
+ * fixes important bugs or such to force cached diff views to
+ * clear.
+ */
+define( 'MW_DIFF_VERSION', '1.11a' );
+
+/**
+ * @todo document
+ * @ingroup DifferenceEngine
+ */
+class DifferenceEngine {
+	/**#@+
+	 * @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?
+	var $mCacheHit = false; // Was the diff fetched from cache?
+	var $htmldiff;
+
+	/**
+	 * Set this to true to add debug info to the HTML output.
+	 * Warning: this may cause RSS readers to spuriously mark articles as "new"
+	 * (bug 20601)
+	 */
+	var $enableDebugComment = false;
+
+	// If true, line X is not displayed when X is 1, for example to increase
+	// readability and conserve space with many small diffs.
+	protected $mReducedLineNumbers = false;
+
+	protected $unhide = false;
+	/**#@-*/
+
+	/**
+	 * 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)
+	 * @param $refreshCache boolean If set, refreshes the diff cache
+	 * @param $htmldiff boolean If set, output using HTMLDiff instead of raw wikicode diff
+	 * @param $unhide boolean If set, allow viewing deleted revs
+	 */
+	function __construct( $titleObj = null, $old = 0, $new = 0, $rcid = 0,
+		$refreshCache = false, $htmldiff = false, $unhide = false )
+	{
+		if ( $titleObj ) {
+			$this->mTitle = $titleObj;
+		} else {
+			global $wgTitle;
+			$this->mTitle = $wgTitle;
+		}
+		wfDebug("DifferenceEngine old '$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);
+			$this->mOldid = $this->mTitle->getPreviousRevisionID( $this->mNewid );
+		} elseif ( 'next' === $new ) {
+			# Show diff between revision $old and the next one.
+			# Get next one from DB.
+			$this->mOldid = intval($old);
+			$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".
+				$this->mNewid = 0;
+			}
+		} else {
+			$this->mOldid = intval($old);
+			$this->mNewid = intval($new);
+			wfRunHooks( 'NewDifferenceEngine', array(&$titleObj, &$this->mOldid, &$this->mNewid, $old, $new) ); 
+		}
+		$this->mRcidMarkPatrolled = intval($rcid);  # force it to be an integer
+		$this->mRefreshCache = $refreshCache;
+		$this->htmldiff = $htmldiff;
+		$this->unhide = $unhide;
+	}
+
+	function setReducedLineNumbers( $value = true ) {
+		$this->mReducedLineNumbers = $value;
+	}
+
+	function getTitle() {
+		return $this->mTitle;
+	}
+	
+	function wasCacheHit() {
+		return $this->mCacheHit;
+	}
+	
+	function getOldid() {
+		return $this->mOldid;
+	}
+	
+	function getNewid() {
+		return $this->mNewid;
+	}
+
+	function showDiffPage( $diffOnly = false ) {
+		global $wgUser, $wgOut, $wgUseExternalEditor, $wgUseRCPatrol, $wgEnableHtmlDiff;
+		wfProfileIn( __METHOD__ );
+
+
+		# If external diffs are enabled both globally and for the user,
+		# we'll use the application/x-external-editor interface to call
+		# an external diff tool like kompare, kdiff3, etc.
+		if($wgUseExternalEditor && $wgUser->getOption('externaldiff')) {
+			global $wgInputEncoding,$wgServer,$wgScript,$wgLang;
+			$wgOut->disable();
+			header ( "Content-type: application/x-external-editor; charset=".$wgInputEncoding );
+			$url1=$this->mTitle->getFullURL( array(
+				'action' => 'raw',
+				'oldid' => $this->mOldid
+			) );
+			$url2=$this->mTitle->getFullURL( array(
+				'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();
+			$d = wfMsgExt( 'missingarticle-diff', array( 'escape' ), $this->mOldid, $this->mNewid );
+			$wgOut->setPagetitle( wfMsg( 'errorpagetitle' ) );
+			$wgOut->addWikiMsg( 'missing-article', "<nowiki>$t</nowiki>", $d );
+			wfProfileOut( __METHOD__ );
+			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( __METHOD__ );
+			return;
+		}
+
+		$wgOut->suppressQuickbar();
+
+		$oldTitle = $this->mOldPage->getPrefixedText();
+		$newTitle = $this->mNewPage->getPrefixedText();
+		if( $oldTitle == $newTitle ) {
+			$wgOut->setPageTitle( $newTitle );
+		} else {
+			$wgOut->setPageTitle( $oldTitle . ', ' . $newTitle );
+		}
+		$wgOut->setSubtitle( wfMsgExt( 'difference', array( 'parseinline' ) ) );
+		$wgOut->setRobotPolicy( 'noindex,nofollow' );
+
+		if ( !$this->mOldPage->userCanRead() || !$this->mNewPage->userCanRead() ) {
+			$wgOut->loginToUse();
+			$wgOut->output();
+			$wgOut->disable();
+			wfProfileOut( __METHOD__ );
+			return;
+		}
+
+		$sk = $wgUser->getSkin();
+
+		// Check if page is editable
+		$editable = $this->mNewRev->getTitle()->userCan( 'edit' );
+		if ( $editable && $this->mNewRev->isCurrent() && $wgUser->isAllowed( 'rollback' ) ) {
+			$rollback = '&nbsp;&nbsp;&nbsp;' . $sk->generateRollback( $this->mNewRev );
+		} else {
+			$rollback = '';
+		}
+
+		// Prepare a change patrol link, if applicable
+		if( $wgUseRCPatrol && $this->mTitle->userCan('patrol') ) {
+			// If we've been given an explicit change identifier, use it; saves time
+			if( $this->mRcidMarkPatrolled ) {
+				$rcid = $this->mRcidMarkPatrolled;
+				$rc = RecentChange::newFromId( $rcid );
+				// Already patrolled?
+				$rcid = is_object($rc) && !$rc->getAttribute('rc_patrolled') ? $rcid : 0;
+			} else {
+				// Look for an unpatrolled change corresponding to this diff
+				$db = wfGetDB( DB_SLAVE );
+				$change = RecentChange::newFromConds(
+					array(
+					// Redundant user,timestamp condition so we can use the existing index
+						'rc_user_text'  => $this->mNewRev->getRawUserText(),
+						'rc_timestamp'  => $db->timestamp( $this->mNewRev->getTimestamp() ),
+						'rc_this_oldid' => $this->mNewid,
+						'rc_last_oldid' => $this->mOldid,
+						'rc_patrolled'  => 0
+					),
+					__METHOD__
+				);
+				if( $change instanceof RecentChange ) {
+					$rcid = $change->mAttribs['rc_id'];
+					$this->mRcidMarkPatrolled = $rcid;
+				} else {
+					// None found
+					$rcid = 0;
+				}
+			}
+			// Build the link
+			if( $rcid ) {
+				$patrol = ' <span class="patrollink">[' . $sk->link(
+					$this->mTitle, 
+					wfMsgHtml( 'markaspatrolleddiff' ),
+					array(),
+					array(
+						'action' => 'markpatrolled',
+						'rcid' => $rcid
+					),
+					array(
+						'known',
+						'noclasses'
+					)
+				) . ']</span>';
+			} else {
+				$patrol = '';
+			}
+		} else {
+			$patrol = '';
+		}
+
+		# Carry over 'diffonly' param via navigation links
+		if( $diffOnly != $wgUser->getBoolOption('diffonly') ) {
+			$query['diffonly'] = $diffOnly;
+		}
+
+		$htmldiffarg = $this->htmlDiffArgument();
+
+		if( $htmldiffarg ) {
+			$query['htmldiff'] = $htmldiffarg['htmldiff'];
+		}
+
+		# Make "previous revision link"
+		$query['diff'] = 'prev';
+		$query['oldid'] = $this->mOldid;
+
+		$prevlink = $sk->link(
+			$this->mTitle,
+			wfMsgHtml( 'previousdiff' ),
+			array(
+				'id' => 'differences-prevlink'
+			),
+			$query,
+			array(
+				'known',
+				'noclasses'
+			)
+		);
+		# Make "next revision link"
+		$query['diff'] = 'next';
+		$query['oldid'] = $this->mNewid;
+
+		if( $this->mNewRev->isCurrent() ) {
+			$nextlink = '&nbsp;';
+		} else {
+			$nextlink = $sk->link(
+				$this->mTitle,
+				wfMsgHtml( 'nextdiff' ),
+				array(
+					'id' => 'differences-nextlink'
+				),
+				$query,
+				array(
+					'known',
+					'noclasses'
+				)
+			);
+		}
+
+		$oldminor = '';
+		$newminor = '';
+
+		if( $this->mOldRev->isMinor() ) {
+			$oldminor = ChangesList::flag( 'minor' );
+		}
+		if( $this->mNewRev->isMinor() ) {
+			$newminor = ChangesList::flag( 'minor' );
+		}
+
+		$rdel = ''; $ldel = '';
+		if( $wgUser->isAllowed( 'deletedhistory' ) ) {
+			// Don't show useless link to people who cannot hide revisions
+			if( $this->mOldRev->getVisibility() || $wgUser->isAllowed( 'deleterevision' ) ) {
+				if( !$this->mOldRev->userCan( Revision::DELETED_RESTRICTED ) ) {
+					// If revision was hidden from sysops
+					$ldel = Xml::tags( 'span', array( 'class' => 'mw-revdelundel-link' ),
+						'(' . wfMsgHtml( 'rev-delundel' ) . ')' );
+				} else {
+					$query = array( 
+						'type' => 'revision',
+						'target' => $this->mOldRev->mTitle->getPrefixedDbkey(),
+						'ids' => $this->mOldRev->getId()
+					);
+					$ldel = $sk->revDeleteLink( $query, $this->mOldRev->isDeleted( Revision::DELETED_RESTRICTED ) );
+				}
+				$ldel = "&nbsp;&nbsp;&nbsp;$ldel ";
+			}
+			// Don't show useless link to people who cannot hide revisions
+			if( $this->mNewRev->getVisibility() || $wgUser->isAllowed( 'deleterevision' ) ) {
+				if( !$this->mNewRev->userCan( Revision::DELETED_RESTRICTED ) ) {
+					// If revision was hidden from sysops
+					$rdel = Xml::tags( 'span', array( 'class'=>'mw-revdelundel-link' ), '('.wfMsgHtml( 'rev-delundel' ).')' );
+				} else {
+					$query = array( 
+						'type' => 'revision',
+						'target' =>  $this->mNewRev->mTitle->getPrefixedDbkey(),
+						'ids' => $this->mNewRev->getId()
+					);
+					$rdel = $sk->revDeleteLink( $query, $this->mNewRev->isDeleted( Revision::DELETED_RESTRICTED ) );
+				}
+				$rdel = "&nbsp;&nbsp;&nbsp;$rdel ";
+			}
+		}
+
+		$oldHeader = '<div id="mw-diff-otitle1"><strong>'.$this->mOldtitle.'</strong></div>' .
+			'<div id="mw-diff-otitle2">' . $sk->revUserTools( $this->mOldRev, !$this->unhide ) . "</div>" .
+			'<div id="mw-diff-otitle3">' . $oldminor . $sk->revComment( $this->mOldRev, !$diffOnly, !$this->unhide ).$ldel."</div>" .
+			'<div id="mw-diff-otitle4">' . $prevlink .'</div>';
+		$newHeader = '<div id="mw-diff-ntitle1"><strong>'.$this->mNewtitle.'</strong></div>' .
+			'<div id="mw-diff-ntitle2">' . $sk->revUserTools( $this->mNewRev, !$this->unhide ) . " $rollback</div>" .
+			'<div id="mw-diff-ntitle3">' . $newminor . $sk->revComment( $this->mNewRev, !$diffOnly, !$this->unhide ).$rdel."</div>" .
+			'<div id="mw-diff-ntitle4">' . $nextlink . $patrol . '</div>';
+
+		# Check if this user can see the revisions
+		$allowed = $this->mOldRev->userCan(Revision::DELETED_TEXT)
+			&& $this->mNewRev->userCan(Revision::DELETED_TEXT);
+		# Check if one of the revisions is deleted/suppressed
+		$deleted = $suppressed = false;
+		if( $this->mOldRev->isDeleted(Revision::DELETED_TEXT) ) {
+			$deleted = true; // old revisions text is hidden
+			if( $this->mOldRev->isDeleted(Revision::DELETED_RESTRICTED) )
+				$suppressed = true; // also suppressed
+		}
+		if( $this->mNewRev->isDeleted(Revision::DELETED_TEXT) ) {
+			$deleted = true; // new revisions text is hidden
+			if( $this->mNewRev->isDeleted(Revision::DELETED_RESTRICTED) )
+				$suppressed = true; // also suppressed
+		}
+		# Output the diff if allowed...
+		if( $deleted && (!$this->unhide || !$allowed) ) {
+			$this->showDiffStyle();
+			$multi = $this->getMultiNotice();
+			$wgOut->addHTML( $this->addHeader( '', $oldHeader, $newHeader, $multi ) );
+			if( !$allowed ) {
+				# Give explanation for why revision is not visible
+				$wgOut->wrapWikiMsg( "<div class='mw-warning plainlinks'>\n$1</div>\n",
+					array( 'rev-deleted-no-diff' ) );
+			} else {
+				# Give explanation and add a link to view the diff...
+				$link = $this->mTitle->getFullUrl( array(
+					'diff' => $this->mNewid,
+					'oldid' => $this->mOldid,
+					'unhide' => 1
+				) );
+				$msg = $suppressed ? 'rev-suppressed-unhide-diff' : 'rev-deleted-unhide-diff';
+				$wgOut->wrapWikiMsg( "<div class='mw-warning plainlinks'>\n$1</div>\n", array( $msg, $link ) );
+			}
+		} else if( $wgEnableHtmlDiff && $this->htmldiff ) {
+			$multi = $this->getMultiNotice();
+			$wgOut->addHTML( '<div class="diff-switchtype">' . $sk->link(
+				$this->mTitle,
+				wfMsgHtml( 'wikicodecomparison' ),
+				array(
+					'id' => 'differences-switchtype'
+				),
+				array(
+					'diff' => $this->mNewid,
+					'oldid' => $this->mOldid,
+					'htmldiff' => 0
+				),
+				array(
+					'known',
+					'noclasses'
+				)
+			) . '</div>');
+			$wgOut->addHTML( $this->addHeader( '', $oldHeader, $newHeader, $multi ) );
+			$this->renderHtmlDiff();
+		} else {
+			if( $wgEnableHtmlDiff ) {
+				$wgOut->addHTML( '<div class="diff-switchtype">' . $sk->link(
+					$this->mTitle,
+					wfMsgHtml( 'visualcomparison' ),
+					array(
+						'id' => 'differences-switchtype'
+					),
+					array(
+						'diff' => $this->mNewid,
+						'oldid' => $this->mOldid,
+						'htmldiff' => 1
+					),
+					array(
+						'known',
+						'noclasses'
+					)
+				) . '</div>');
+			}
+			$this->showDiff( $oldHeader, $newHeader );
+			if( !$diffOnly ) {
+				$this->renderNewRevision();
+			}
+		}
+		wfProfileOut( __METHOD__ );
+	}
+
+	/**
+	 * Show the new revision of the page.
+	 */
+	function renderNewRevision() {
+		global $wgOut, $wgUser;
+		wfProfileIn( __METHOD__ );
+
+		$wgOut->addHTML( "<hr /><h2>{$this->mPagetitle}</h2>\n" );
+		# Add deleted rev tag if needed
+		if( !$this->mNewRev->userCan(Revision::DELETED_TEXT) ) {
+			$wgOut->wrapWikiMsg( "<div class='mw-warning plainlinks'>\n$1</div>\n", 'rev-deleted-text-permission' );
+		} else if( $this->mNewRev->isDeleted(Revision::DELETED_TEXT) ) {
+			$wgOut->wrapWikiMsg( "<div class='mw-warning plainlinks'>\n$1</div>\n", 'rev-deleted-text-view' );
+		}
+
+		if( !$this->mNewRev->isCurrent() ) {
+			$oldEditSectionSetting = $wgOut->parserOptions()->setEditSection( false );
+		}
+
+		$this->loadNewText();
+		if( is_object( $this->mNewRev ) ) {
+			$wgOut->setRevisionId( $this->mNewRev->getId() );
+		}
+
+		if( $this->mTitle->isCssJsSubpage() || $this->mTitle->isCssOrJsPage() ) {
+			// Stolen from Article::view --AG 2007-10-11
+			// Give hooks a chance to customise the output
+			if( wfRunHooks( 'ShowRawCssJs', array( $this->mNewtext, $this->mTitle, $wgOut ) ) ) {
+				// Wrap the whole lot in a <pre> and don't parse
+				$m = array();
+				preg_match( '!\.(css|js)$!u', $this->mTitle->getText(), $m );
+				$wgOut->addHTML( "<pre class=\"mw-code mw-{$m[1]}\" dir=\"ltr\">\n" );
+				$wgOut->addHTML( htmlspecialchars( $this->mNewtext ) );
+				$wgOut->addHTML( "\n</pre>\n" );
+			}
+		} else {
+			$wgOut->addWikiTextTidy( $this->mNewtext );
+		}
+
+		if( is_object( $this->mNewRev ) && !$this->mNewRev->isCurrent() ) {
+			$wgOut->parserOptions()->setEditSection( $oldEditSectionSetting );
+		}
+		# Add redundant patrol link on bottom...
+		if( $this->mRcidMarkPatrolled && $this->mTitle->quickUserCan('patrol') ) {
+			$sk = $wgUser->getSkin();
+			$wgOut->addHTML(
+				"<div class='patrollink'>[" . $sk->link(
+					$this->mTitle,
+					wfMsgHtml( 'markaspatrolleddiff' ),
+					array(),
+					array(
+						'action' => 'markpatrolled',
+						'rcid' => $this->mRcidMarkPatrolled
+					)
+				) . ']</div>'
+			 );
+		}
+
+		wfProfileOut( __METHOD__ );
+	}
+
+
+	function renderHtmlDiff() {
+		global $wgOut, $wgParser, $wgDebugComments;
+		wfProfileIn( __METHOD__ );
+
+		$this->showDiffStyle();
+
+		$wgOut->addHTML( '<h2>'.wfMsgHtml( 'visual-comparison' )."</h2>\n" );
+		#add deleted rev tag if needed
+		if( !$this->mNewRev->userCan(Revision::DELETED_TEXT) ) {
+			$wgOut->wrapWikiMsg( "<div class='mw-warning plainlinks'>\n$1</div>\n", 'rev-deleted-text-permission' );
+		} else if( $this->mNewRev->isDeleted(Revision::DELETED_TEXT) ) {
+			$wgOut->wrapWikiMsg( "<div class='mw-warning plainlinks'>\n$1</div>\n", 'rev-deleted-text-view' );
+		}
+
+		if( !$this->mNewRev->isCurrent() ) {
+			$oldEditSectionSetting = $wgOut->parserOptions()->setEditSection( false );
+		}
+
+		$this->loadText();
+
+		// Old revision
+		if( is_object( $this->mOldRev ) ) {
+			$wgOut->setRevisionId( $this->mOldRev->getId() );
+		}
+
+		$popts = $wgOut->parserOptions();
+		$oldTidy = $popts->setTidy( true );
+		$popts->setEditSection( false );
+
+		$parserOutput = $wgParser->parse( $this->mOldtext, $this->getTitle(), $popts, true, true, $wgOut->getRevisionId() );
+		$popts->setTidy( $oldTidy );
+
+		//only for new?
+		//$wgOut->addParserOutputNoText( $parserOutput );
+		$oldHtml = $parserOutput->getText();
+		wfRunHooks( 'OutputPageBeforeHTML', array( &$wgOut, &$oldHtml ) );
+
+		// New revision
+		if( is_object( $this->mNewRev ) ) {
+			$wgOut->setRevisionId( $this->mNewRev->getId() );
+		}
+
+		$popts = $wgOut->parserOptions();
+		$oldTidy = $popts->setTidy( true );
+
+		$parserOutput = $wgParser->parse( $this->mNewtext, $this->getTitle(), $popts, true, true, $wgOut->getRevisionId() );
+		$popts->setTidy( $oldTidy );
+
+		$wgOut->addParserOutputNoText( $parserOutput );
+		$newHtml = $parserOutput->getText();
+		wfRunHooks( 'OutputPageBeforeHTML', array( &$wgOut, &$newHtml ) );
+
+		unset($parserOutput, $popts);
+
+		$differ = new HTMLDiffer(new DelegatingContentHandler($wgOut));
+		$differ->htmlDiff($oldHtml, $newHtml);
+		if ( $wgDebugComments ) {
+			$wgOut->addHTML( "\n<!-- HtmlDiff Debug Output:\n" . HTMLDiffer::getDebugOutput() . " End Debug -->" );
+		}
+
+		wfProfileOut( __METHOD__ );
+	}
+
+	/**
+	 * Show the first revision of an article. Uses normal diff headers in
+	 * contrast to normal "old revision" display style.
+	 */
+	function showFirstRevision() {
+		global $wgOut, $wgUser;
+		wfProfileIn( __METHOD__ );
+
+		# Get article text from the DB
+		#
+		if ( ! $this->loadNewText() ) {
+			$t = $this->mTitle->getPrefixedText();
+			$d = wfMsgExt( 'missingarticle-diff', array( 'escape' ), $this->mOldid, $this->mNewid );
+			$wgOut->setPagetitle( wfMsg( 'errorpagetitle' ) );
+			$wgOut->addWikiMsg( 'missing-article', "<nowiki>$t</nowiki>", $d );
+			wfProfileOut( __METHOD__ );
+			return;
+		}
+		if ( $this->mNewRev->isCurrent() ) {
+			$wgOut->setArticleFlag( true );
+		}
+
+		# Check if user is allowed to look at this page. If not, bail out.
+		#
+		if ( !$this->mTitle->userCanRead() ) {
+			$wgOut->loginToUse();
+			$wgOut->output();
+			wfProfileOut( __METHOD__ );
+			throw new MWException("Permission Error: you do not have access to view this page");
+		}
+
+		# Prepare the header box
+		#
+		$sk = $wgUser->getSkin();
+
+		$next = $this->mTitle->getNextRevisionID( $this->mNewid );
+		if( !$next ) {
+			$nextlink = '';
+		} else {
+			$nextlink = '<br/>' . $sk->link(
+				$this->mTitle,
+				wfMsgHtml( 'nextdiff' ),
+				array(
+					'id' => 'differences-nextlink'
+				),
+				array(
+					'diff' => 'next',
+					'oldid' => $this->mNewid,
+					$this->htmlDiffArgument()
+				),
+				array(
+					'known',
+					'noclasses'
+				)
+			);
+		}
+		$header = "<div class=\"firstrevisionheader\" style=\"text-align: center\">" .
+			$sk->revUserTools( $this->mNewRev ) . "<br/>" . $sk->revComment( $this->mNewRev ) . $nextlink . "</div>\n";
+
+		$wgOut->addHTML( $header );
+
+		$wgOut->setSubtitle( wfMsgExt( 'difference', array( 'parseinline' ) ) );
+		$wgOut->setRobotPolicy( 'noindex,nofollow' );
+
+		wfProfileOut( __METHOD__ );
+	}
+
+	function htmlDiffArgument(){
+		global $wgEnableHtmlDiff;
+		if($wgEnableHtmlDiff){
+			if($this->htmldiff){
+				return array( 'htmldiff' => 1 );
+			}else{
+				return array( 'htmldiff' => 0 );
+			}
+		}else{
+			return array();
+		}
+	}
+
+	/**
+	 * 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->addWikiMsg( 'missing-article', "<nowiki>(fixme, bug)</nowiki>", '' );
+			return false;
+		} else {
+			$this->showDiffStyle();
+			$wgOut->addHTML( $diff );
+			return true;
+		}
+	}
+
+	/**
+	 * Add style sheets and supporting JS for diff display.
+	 */
+	function showDiffStyle() {
+		global $wgStylePath, $wgStyleVersion, $wgOut;
+		$wgOut->addStyle( 'common/diff.css' );
+
+		// JS is needed to detect old versions of Mozilla to work around an annoyance bug.
+		$wgOut->addScript( "<script type=\"text/javascript\" src=\"$wgStylePath/common/diff.js?$wgStyleVersion\"></script>" );
+	}
+
+	/**
+	 * Get complete diff table, including header
+	 *
+	 * @param Title $otitle Old title
+	 * @param Title $ntitle New title
+	 * @return mixed
+	 */
+	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
+	 *
+	 * @return mixed
+	 */
+	function getDiffBody() {
+		global $wgMemc;
+		wfProfileIn( __METHOD__ );
+		$this->mCacheHit = true;
+		// Check if the diff should be hidden from this user
+		if ( !$this->loadRevisionData() )
+			return '';
+		if ( $this->mOldRev && !$this->mOldRev->userCan(Revision::DELETED_TEXT) ) {
+			return '';
+		} else if ( $this->mNewRev && !$this->mNewRev->userCan(Revision::DELETED_TEXT) ) {
+			return '';
+		} else if ( $this->mOldRev && $this->mNewRev && $this->mOldRev->getID() == $this->mNewRev->getID() ) {
+			return '';
+		}
+		// Cacheable?
+		$key = false;
+		if ( $this->mOldid && $this->mNewid ) {
+			$key = wfMemcKey( 'diff', 'version', MW_DIFF_VERSION, 'oldid', $this->mOldid, 'newid', $this->mNewid );
+			// Try cache
+			if ( !$this->mRefreshCache ) {
+				$difftext = $wgMemc->get( $key );
+				if ( $difftext ) {
+					wfIncrStats( 'diff_cache_hit' );
+					$difftext = $this->localiseLineNumbers( $difftext );
+					$difftext .= "\n<!-- diff cache key $key -->\n";
+					wfProfileOut( __METHOD__ );
+					return $difftext;
+				}
+			} // don't try to load but save the result
+		}
+		$this->mCacheHit = false;
+
+		// Loadtext is permission safe, this just clears out the diff
+		if ( !$this->loadText() ) {
+			wfProfileOut( __METHOD__ );
+			return false;
+		}
+
+		$difftext = $this->generateDiffBody( $this->mOldtext, $this->mNewtext );
+
+		// Save to cache for 7 days
+		if ( !wfRunHooks( 'AbortDiffCache', array( &$this ) ) ) {
+			wfIncrStats( 'diff_uncacheable' );
+		} else 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( __METHOD__ );
+		return $difftext;
+	}
+
+	/**
+	 * Make sure the proper modules are loaded before we try to
+	 * make the diff
+	 */
+	private function initDiffEngines() {
+		global $wgExternalDiffEngine;
+		if ( $wgExternalDiffEngine == 'wikidiff' && !function_exists( 'wikidiff_do_diff' ) ) {
+			wfProfileIn( __METHOD__ . '-php_wikidiff.so' );
+			wfSuppressWarnings();
+			dl( 'php_wikidiff.so' );
+			wfRestoreWarnings();
+			wfProfileOut( __METHOD__ . '-php_wikidiff.so' );
+		}
+		else if ( $wgExternalDiffEngine == 'wikidiff2' && !function_exists( 'wikidiff2_do_diff' ) ) {
+			wfProfileIn( __METHOD__ . '-php_wikidiff2.so' );
+			wfSuppressWarnings();
+			dl( 'php_wikidiff2.so' );
+			wfRestoreWarnings();
+			wfProfileOut( __METHOD__ . '-php_wikidiff2.so' );
+		}
+	}
+
+	/**
+	 * Generate a diff, no caching
+	 * $otext and $ntext must be already segmented
+	 */
+	function generateDiffBody( $otext, $ntext ) {
+		global $wgExternalDiffEngine, $wgContLang;
+
+		$otext = str_replace( "\r\n", "\n", $otext );
+		$ntext = str_replace( "\r\n", "\n", $ntext );
+
+		$this->initDiffEngines();
+
+		if ( $wgExternalDiffEngine == 'wikidiff' && function_exists( 'wikidiff_do_diff' ) ) {
+			# For historical reasons, external diff engine expects
+			# input text to be HTML-escaped already
+			$otext = htmlspecialchars ( $wgContLang->segmentForDiff( $otext ) );
+			$ntext = htmlspecialchars ( $wgContLang->segmentForDiff( $ntext ) );
+			return $wgContLang->unsegementForDiff( wikidiff_do_diff( $otext, $ntext, 2 ) ) .
+			$this->debug( 'wikidiff1' );
+		}
+
+		if ( $wgExternalDiffEngine == 'wikidiff2' && function_exists( 'wikidiff2_do_diff' ) ) {
+			# Better external diff engine, the 2 may some day be dropped
+			# This one does the escaping and segmenting itself
+			wfProfileIn( 'wikidiff2_do_diff' );
+			$text = wikidiff2_do_diff( $otext, $ntext, 2 );
+			$text .= $this->debug( 'wikidiff2' );
+			wfProfileOut( 'wikidiff2_do_diff' );
+			return $text;
+		}
+		if ( $wgExternalDiffEngine != 'wikidiff3' && $wgExternalDiffEngine !== false ) {
+			# Diff via the shell
+			global $wgTmpDirectory;
+			$tempName1 = tempnam( $wgTmpDirectory, 'diff_' );
+			$tempName2 = tempnam( $wgTmpDirectory, 'diff_' );
+
+			$tempFile1 = fopen( $tempName1, "w" );
+			if ( !$tempFile1 ) {
+				wfProfileOut( __METHOD__ );
+				return false;
+			}
+			$tempFile2 = fopen( $tempName2, "w" );
+			if ( !$tempFile2 ) {
+				wfProfileOut( __METHOD__ );
+				return false;
+			}
+			fwrite( $tempFile1, $otext );
+			fwrite( $tempFile2, $ntext );
+			fclose( $tempFile1 );
+			fclose( $tempFile2 );
+			$cmd = wfEscapeShellArg( $wgExternalDiffEngine, $tempName1, $tempName2 );
+			wfProfileIn( __METHOD__ . "-shellexec" );
+			$difftext = wfShellExec( $cmd );
+			$difftext .= $this->debug( "external $wgExternalDiffEngine" );
+			wfProfileOut( __METHOD__ . "-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 ) ) .
+		$this->debug();
+	}
+
+	/**
+	 * Generate a debug comment indicating diff generating time,
+	 * server node, and generator backend.
+	 */
+	protected function debug( $generator="internal" ) {
+		global $wgShowHostnames;
+		if ( !$this->enableDebugComment ) {
+			return '';
+		}
+		$data = array( $generator );
+		if( $wgShowHostnames ) {
+			$data[] = wfHostname();
+		}
+		$data[] = wfTimestamp( TS_DB );
+		return "<!-- diff generator: " .
+		implode( " ",
+		array_map(
+					"htmlspecialchars",
+		$data ) ) .
+			" -->\n";
+	}
+
+	/**
+	 * 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;
+		if ( $matches[1] === '1' && $this->mReducedLineNumbers ) return '';
+		return wfMsgExt( 'lineno', 'escape', $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 );
+	}
+
+
+	/**
+	 * Add the header to a diff body
+	 */
+	static function addHeader( $diff, $otitle, $ntitle, $multi = '' ) {
+		$colspan = 1;
+		$header = "<table class='diff'>";
+		if( $diff ) { // Safari/Chrome show broken output if cols not used
+			$header .= "
+			<col class='diff-marker' />
+			<col class='diff-content' />
+			<col class='diff-marker' />
+			<col class='diff-content' />";
+			$colspan = 2;
+		}
+		$header .= "
+		<tr valign='top'>
+		<td colspan='$colspan' class='diff-otitle'>{$otitle}</td>
+		<td colspan='$colspan' class='diff-ntitle'>{$ntitle}</td>
+		</tr>";
+
+		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;
+		$this->mRevisionsLoaded = true;
+	}
+
+	/**
+	 * 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, $wgUser;
+		if ( $this->mRevisionsLoaded ) {
+			return true;
+		} else {
+			// Whether it succeeds or fails, we don't want to try again
+			$this->mRevisionsLoaded = true;
+		}
+
+		// Load the new revision object
+		$this->mNewRev = $this->mNewid
+			? Revision::newFromId( $this->mNewid )
+			: Revision::newFromTitle( $this->mTitle );
+		if( !$this->mNewRev instanceof Revision )
+			return false;
+
+		// Update the new revision ID in case it was 0 (makes life easier doing UI stuff)
+		$this->mNewid = $this->mNewRev->getId();
+
+		// Check if page is editable
+		$editable = $this->mNewRev->getTitle()->userCan( 'edit' );
+
+		// Set assorted variables
+		$timestamp = $wgLang->timeanddate( $this->mNewRev->getTimestamp(), true );
+		$dateofrev = $wgLang->date( $this->mNewRev->getTimestamp(), true );
+		$timeofrev = $wgLang->time( $this->mNewRev->getTimestamp(), true );
+		$this->mNewPage = $this->mNewRev->getTitle();
+		if( $this->mNewRev->isCurrent() ) {
+			$newLink = $this->mNewPage->escapeLocalUrl( array(
+				'oldid' => $this->mNewid
+			) );
+			$this->mPagetitle = htmlspecialchars( wfMsg(
+				'currentrev-asof',
+				$timestamp,
+				$dateofrev,
+				$timeofrev
+			) );
+			$newEdit = $this->mNewPage->escapeLocalUrl( array(
+				'action' => 'edit'
+			) );
+
+			$this->mNewtitle = "<a href='$newLink'>{$this->mPagetitle}</a>";
+			$this->mNewtitle .= " (<a href='$newEdit'>" . wfMsgHtml( $editable ? 'editold' : 'viewsourceold' ) . "</a>)";
+		} else {
+			$newLink = $this->mNewPage->escapeLocalUrl( array(
+				'oldid' => $this->mNewid
+			) );
+			$newEdit = $this->mNewPage->escapeLocalUrl( array(
+				'action' => 'edit',
+				'oldid' => $this->mNewid
+			) );
+			$this->mPagetitle = htmlspecialchars( wfMsg(
+				'revisionasof',
+				$timestamp,
+				$dateofrev,
+				$timeofrev
+			) );
+
+			$this->mNewtitle = "<a href='$newLink'>{$this->mPagetitle}</a>";
+			$this->mNewtitle .= " (<a href='$newEdit'>" . wfMsgHtml( $editable ? 'editold' : 'viewsourceold' ) . "</a>)";
+		}
+		if( !$this->mNewRev->userCan(Revision::DELETED_TEXT) ) {
+			$this->mNewtitle = "<span class='history-deleted'>{$this->mPagetitle}</span>";
+		} else if ( $this->mNewRev->isDeleted(Revision::DELETED_TEXT) ) {
+			$this->mNewtitle = "<span class='history-deleted'>{$this->mNewtitle}</span>";
+		}
+
+		// 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; */
+
+		if( is_null( $this->mOldRev ) ) {
+			return false;
+		}
+
+		if ( $this->mOldRev ) {
+			$this->mOldPage = $this->mOldRev->getTitle();
+
+			$t = $wgLang->timeanddate( $this->mOldRev->getTimestamp(), true );
+			$dateofrev = $wgLang->date( $this->mOldRev->getTimestamp(), true );
+			$timeofrev = $wgLang->time( $this->mOldRev->getTimestamp(), true );
+			$oldLink = $this->mOldPage->escapeLocalUrl( array(
+				'oldid' => $this->mOldid
+			) );
+			$oldEdit = $this->mOldPage->escapeLocalUrl( array(
+				'action' => 'edit',
+				'oldid' => $this->mOldid
+			) );
+			$this->mOldPagetitle = htmlspecialchars( wfMsg( 'revisionasof', $t, $dateofrev, $timeofrev ) );
+
+			$this->mOldtitle = "<a href='$oldLink'>{$this->mOldPagetitle}</a>"
+			. " (<a href='$oldEdit'>" . wfMsgHtml( $editable ? 'editold' : 'viewsourceold' ) . "</a>)";
+			// Add an "undo" link
+			$newUndo = $this->mNewPage->escapeLocalUrl( array(
+				'action' => 'edit',
+				'undoafter' => $this->mOldid,
+				'undo' => $this->mNewid
+			) );
+			$htmlLink = htmlspecialchars( wfMsg( 'editundo' ) );
+			$htmlTitle = $wgUser->getSkin()->tooltip( 'undo' );
+			if( $editable && !$this->mOldRev->isDeleted( Revision::DELETED_TEXT ) && !$this->mNewRev->isDeleted( Revision::DELETED_TEXT ) ) {
+				$this->mNewtitle .= " (<a href='$newUndo' $htmlTitle>" . $htmlLink . "</a>)";
+			}
+
+			if( !$this->mOldRev->userCan( Revision::DELETED_TEXT ) ) {
+				$this->mOldtitle = '<span class="history-deleted">' . $this->mOldPagetitle . '</span>';
+			} else if( $this->mOldRev->isDeleted( Revision::DELETED_TEXT ) ) {
+				$this->mOldtitle = '<span class="history-deleted">' . $this->mOldtitle . '</span>';
+			}
+		}
+
+		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 ) {
+			$this->mOldtext = $this->mOldRev->getText( Revision::FOR_THIS_USER );
+			if ( $this->mOldtext === false ) {
+				return false;
+			}
+		}
+		if ( $this->mNewRev ) {
+			$this->mNewtext = $this->mNewRev->getText( Revision::FOR_THIS_USER );
+			if ( $this->mNewtext === false ) {
+				return false;
+			}
+		}
+		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( Revision::FOR_THIS_USER );
+		return true;
+	}
+}
-- 
2.20.1