From dcac5f193e3720c70f5eb086a9905dcda0155baa Mon Sep 17 00:00:00 2001
From: Chad Horohoe <demon@users.mediawiki.org>
Date: Wed, 28 Oct 2009 18:18:05 +0000
Subject: [PATCH] (bug 19859) Remove HTMLDiff. Could possibly be salvaged as an
 extension one day, but not today. DifferenceEngine and friends will need some
 refactoring to allow spinning this off. In the meantime, removing the
 mostly-broken experimental feature. Its always in the logs if anyone wants to
 reuse the code somewhere else one day

---
 RELEASE-NOTES                         |    2 +
 includes/Article.php                  |    3 +-
 includes/AutoLoader.php               |   22 -
 includes/DefaultSettings.php          |    3 -
 includes/HistoryPage.php              |   37 +-
 includes/diff/DifferenceInterface.php |  130 +---
 includes/diff/HTMLDiff.php            | 1009 -------------------------
 includes/diff/Nodes.php               |  439 -----------
 languages/messages/MessagesEn.php     |   60 --
 maintenance/language/messageTypes.inc |    1 -
 maintenance/language/messages.inc     |   62 --
 11 files changed, 13 insertions(+), 1755 deletions(-)
 delete mode 100644 includes/diff/HTMLDiff.php
 delete mode 100644 includes/diff/Nodes.php

diff --git a/RELEASE-NOTES b/RELEASE-NOTES
index e3ca123461..11b6e56461 100644
--- a/RELEASE-NOTES
+++ b/RELEASE-NOTES
@@ -89,6 +89,7 @@ it from source control: http://www.mediawiki.org/wiki/Download_from_SVN
   maintenance
 * $wgCapitalLinkOverrides added to configure per-namespace capitalization
 * (bug 21172) $wgSorbsUrl can now be an array with multiple DNSBL
+* $wgEnableHtmlDiff has been removed
 
 === New features in 1.16 ===
 
@@ -604,6 +605,7 @@ it from source control: http://www.mediawiki.org/wiki/Download_from_SVN
 * User::isValidPassword now only returns boolean results, User::getPasswordValidity
   can be used to get an error message string
 * The error message shown in Special:ChangePassword now parses wiki markup
+* (bug 19859) Removed experimental HTMLDiff feature
 
 == API changes in 1.16 ==
 
diff --git a/includes/Article.php b/includes/Article.php
index 9e6545a18c..50b1c5a4c1 100644
--- a/includes/Article.php
+++ b/includes/Article.php
@@ -943,11 +943,10 @@ class Article {
 		$rcid = $wgRequest->getVal( 'rcid' );
 		$diffOnly = $wgRequest->getBool( 'diffonly', $wgUser->getOption( 'diffonly' ) );
 		$purge = $wgRequest->getVal( 'action' ) == 'purge';
-		$htmldiff = $wgRequest->getBool( 'htmldiff' );
 		$unhide = $wgRequest->getInt('unhide') == 1;
 		$oldid = $this->getOldID();
 
-		$de = new DifferenceEngine( $this->mTitle, $oldid, $diff, $rcid, $purge, $htmldiff, $unhide );
+		$de = new DifferenceEngine( $this->mTitle, $oldid, $diff, $rcid, $purge, $unhide );
 		// DifferenceEngine directly fetched the revision:
 		$this->mRevIdFetched = $de->mNewid;
 		$de->showDiffPage( $diffOnly );
diff --git a/includes/AutoLoader.php b/includes/AutoLoader.php
index 807de081d9..6ca9ee4fb2 100644
--- a/includes/AutoLoader.php
+++ b/includes/AutoLoader.php
@@ -376,13 +376,7 @@ $wgAutoloadLocalClasses = array(
 	'IBM_DB2Field' => 'includes/db/DatabaseIbm_db2.php',
 
 	# includes/diff
-	'AncestorComparator' => 'includes/diff/HTMLDiff.php',
-	'AnchorToString' => 'includes/diff/HTMLDiff.php',
 	'ArrayDiffFormatter' => 'includes/diff/DifferenceEngine.php',
-	'BodyNode' => 'includes/diff/Nodes.php',
-	'ChangeText' => 'includes/diff/HTMLDiff.php',
-	'ChangeTextGenerator' => 'includes/diff/HTMLDiff.php',
-	'DelegatingContentHandler' => 'includes/diff/HTMLDiff.php',
 	'_DiffEngine' => 'includes/diff/DifferenceEngine.php',
 	'DifferenceEngine' => 'includes/diff/DifferenceInterface.php',
 	'DiffFormatter' => 'includes/diff/DifferenceEngine.php',
@@ -392,27 +386,11 @@ $wgAutoloadLocalClasses = array(
 	'_DiffOp_Copy' => 'includes/diff/DifferenceEngine.php',
 	'_DiffOp_Delete' => 'includes/diff/DifferenceEngine.php',
 	'_DiffOp' => 'includes/diff/DifferenceEngine.php',
-	'DomTreeBuilder' => 'includes/diff/HTMLDiff.php',
-	'DummyNode' => 'includes/diff/Nodes.php',
-	'HTMLDiffer' => 'includes/diff/HTMLDiff.php',
-	'HTMLOutput' => 'includes/diff/HTMLDiff.php',
 	'_HWLDF_WordAccumulator' => 'includes/diff/DifferenceEngine.php',
-	'ImageNode' => 'includes/diff/Nodes.php',
-	'LastCommonParentResult' => 'includes/diff/HTMLDiff.php',
 	'MappedDiff' => 'includes/diff/DifferenceEngine.php',
-	'Modification' => 'includes/diff/HTMLDiff.php',
-	'NoContentTagToString' => 'includes/diff/HTMLDiff.php',
-	'Node' => 'includes/diff/Nodes.php',
 	'RangeDifference' => 'includes/diff/Diff.php',
 	'TableDiffFormatter' => 'includes/diff/DifferenceEngine.php',
-	'TagNode' => 'includes/diff/Nodes.php',
-	'TagToString' => 'includes/diff/HTMLDiff.php',
-	'TagToStringFactory' => 'includes/diff/HTMLDiff.php',
-	'TextNode' => 'includes/diff/Nodes.php',
-	'TextNodeDiffer' => 'includes/diff/HTMLDiff.php',
-	'TextOnlyComparator' => 'includes/diff/HTMLDiff.php',
 	'UnifiedDiffFormatter' => 'includes/diff/DifferenceEngine.php',
-	'WhiteSpaceNode' => 'includes/diff/Nodes.php',
 	'WikiDiff3' => 'includes/diff/Diff.php',
 	'WordLevelDiff' => 'includes/diff/DifferenceEngine.php',
 
diff --git a/includes/DefaultSettings.php b/includes/DefaultSettings.php
index 537d52c26e..99c0d887d3 100644
--- a/includes/DefaultSettings.php
+++ b/includes/DefaultSettings.php
@@ -2892,9 +2892,6 @@ $wgMaxTocLevel = 999;
 /** Name of the external diff engine to use */
 $wgExternalDiffEngine = false;
 
-/** Whether to use inline diff */
-$wgEnableHtmlDiff = false;
-
 /** Use RC Patrolling to check for vandalism */
 $wgUseRCPatrol = true;
 
diff --git a/includes/HistoryPage.php b/includes/HistoryPage.php
index b866a257c5..01d95e0d16 100644
--- a/includes/HistoryPage.php
+++ b/includes/HistoryPage.php
@@ -359,7 +359,7 @@ class HistoryPager extends ReverseChronologicalPager {
 	 * @return string HTML output
 	 */
 	function getStartBody() {
-		global $wgScript, $wgEnableHtmlDiff, $wgUser, $wgOut, $wgContLang;
+		global $wgScript, $wgUser, $wgOut, $wgContLang;
 		$this->lastRow = false;
 		$this->counter = 1;
 		$this->oldIdChecked = 0;
@@ -385,34 +385,13 @@ class HistoryPager extends ReverseChronologicalPager {
 				wfMsg( 'showhideselectedversions' )
 			) . "\n";
 		}
-		if( $wgEnableHtmlDiff ) {
-			$this->buttons .= Xml::element( 'button',
-				array(
-					'type'      => 'submit',
-					'name'      => 'htmldiff',
-					'value'     => '1',
-					'class'     => 'historysubmit',
-					'accesskey' => wfMsg( 'accesskey-visualcomparison' ),
-					'title'     => wfMsg( 'tooltip-compareselectedversions' ),
-				),
-				wfMsg( 'visualcomparison')
-			) . "\n";
-			$this->buttons .= $this->submitButton( wfMsg( 'wikicodecomparison'),
-				array(
-					'class'     => 'historysubmit',
-					'accesskey' => wfMsg( 'accesskey-compareselectedversions' ),
-					'title'     => wfMsg( 'tooltip-compareselectedversions' ),
-				)
-			) . "\n";
-		} else {
-			$this->buttons .= $this->submitButton( wfMsg( 'compareselectedversions'),
-				array(
-					'class'     => 'historysubmit',
-					'accesskey' => wfMsg( 'accesskey-compareselectedversions' ),
-					'title'     => wfMsg( 'tooltip-compareselectedversions' ),
-				)
-			) . "\n";
-		}
+		$this->buttons .= $this->submitButton( wfMsg( 'compareselectedversions'),
+			array(
+				'class'     => 'historysubmit',
+				'accesskey' => wfMsg( 'accesskey-compareselectedversions' ),
+				'title'     => wfMsg( 'tooltip-compareselectedversions' ),
+			)
+		) . "\n";
 		$this->buttons .= '</div>';
 		$s .= $this->buttons . '<ul id="pagehistory">' . "\n";
 		return $s;
diff --git a/includes/diff/DifferenceInterface.php b/includes/diff/DifferenceInterface.php
index 35f8542d56..030ade189d 100644
--- a/includes/diff/DifferenceInterface.php
+++ b/includes/diff/DifferenceInterface.php
@@ -28,7 +28,6 @@ class DifferenceEngine {
 	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.
@@ -51,11 +50,10 @@ class DifferenceEngine {
 	 * @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 )
+		$refreshCache = false, $unhide = false )
 	{
 		if ( $titleObj ) {
 			$this->mTitle = $titleObj;
@@ -87,7 +85,6 @@ class DifferenceEngine {
 		}
 		$this->mRcidMarkPatrolled = intval($rcid);  # force it to be an integer
 		$this->mRefreshCache = $refreshCache;
-		$this->htmldiff = $htmldiff;
 		$this->unhide = $unhide;
 	}
 
@@ -112,7 +109,7 @@ class DifferenceEngine {
 	}
 
 	function showDiffPage( $diffOnly = false ) {
-		global $wgUser, $wgOut, $wgUseExternalEditor, $wgUseRCPatrol, $wgEnableHtmlDiff;
+		global $wgUser, $wgOut, $wgUseExternalEditor, $wgUseRCPatrol;
 		wfProfileIn( __METHOD__ );
 
 
@@ -264,12 +261,6 @@ CONTROL;
 			$query['diffonly'] = $diffOnly;
 		}
 
-		$htmldiffarg = $this->htmlDiffArgument();
-
-		if( $htmldiffarg ) {
-			$query['htmldiff'] = $htmldiffarg['htmldiff'];
-		}
-
 		# Make "previous revision link"
 		$query['diff'] = 'prev';
 		$query['oldid'] = $this->mOldid;
@@ -401,47 +392,8 @@ CONTROL;
 				$msg = $suppressed ? 'rev-suppressed-unhide-diff' : 'rev-deleted-unhide-diff';
 				$wgOut->wrapWikiMsg( "<div class='mw-warning plainlinks'>\n$1</div>\n", array( $msg, $link ) );
 			}
-		# Otherwise, output the HTML diff if requested...
-		} 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 ) );
-			# Add deletion notice if the user is viewing deleted content
-			if( $deleted ) {
-				$msg = $suppressed ? 'rev-suppressed-diff-view' : 'rev-deleted-diff-view';
-				$wgOut->wrapWikiMsg( "<div class='mw-warning plainlinks'>\n$1</div>\n", $msg );
-			}
-			$this->renderHtmlDiff();
 		# Otherwise, output a regular diff...
 		} 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>');
-			}
 			# Add deletion notice if the user is viewing deleted content
 			$notice = '';
 			if( $deleted ) {
@@ -517,70 +469,6 @@ CONTROL;
 		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.
@@ -629,7 +517,6 @@ CONTROL;
 				array(
 					'diff' => 'next',
 					'oldid' => $this->mNewid,
-					$this->htmlDiffArgument()
 				),
 				array(
 					'known',
@@ -648,19 +535,6 @@ CONTROL;
 		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
diff --git a/includes/diff/HTMLDiff.php b/includes/diff/HTMLDiff.php
deleted file mode 100644
index df9f4eb81f..0000000000
--- a/includes/diff/HTMLDiff.php
+++ /dev/null
@@ -1,1009 +0,0 @@
-<?php
-
-/** Copyright (C) 2008 Guy Van den Broeck <guy@guyvdb.eu>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
- * or see http://www.gnu.org/
- * 
- * @ingroup DifferenceEngine
- */
-
-/**
- * When detecting the last common parent of two nodes, all results are stored as
- * a LastCommonParentResult.
- */
-class LastCommonParentResult {
-
-	// Parent
-	public $parent;
-
-	// Splitting
-	public $splittingNeeded = false;
-
-	// Depth
-	public $lastCommonParentDepth = -1;
-
-	// Index
-	public $indexInLastCommonParent = -1;
-}
-
-class Modification{
-
-	const NONE = 1;
-	const REMOVED = 2;
-	const ADDED = 4;
-	const CHANGED = 8;
-
-	public $type;
-
-	public $id = -1;
-
-	public $firstOfID = false;
-
-	public $changes;
-
-	function __construct($type) {
-		$this->type = $type;
-	}
-
-	public static function typeToString($type) {
-		switch($type) {
-			case self::NONE: return 'none';
-			case self::REMOVED: return 'removed';
-			case self::ADDED: return 'added';
-			case self::CHANGED: return 'changed';
-		}
-	}
-}
-
-class DomTreeBuilder {
-
-	public $textNodes = array();
-
-	public $bodyNode;
-
-	private $currentParent;
-
-	private $newWord = '';
-
-	protected $bodyStarted = false;
-
-	protected $bodyEnded = false;
-
-	private $whiteSpaceBeforeThis = false;
-
-	private $lastSibling;
-
-	private $notInPre = true;
-
-	function __construct() {
-		$this->bodyNode = $this->currentParent = new BodyNode();
-		$this->lastSibling = new DummyNode();
-	}
-
-	/**
-	 * Must be called manually
-	 */
-	public function endDocument() {
-		$this->endWord();
-		HTMLDiffer::diffDebug( count($this->textNodes) . " text nodes in document.\n" );
-	}
-
-	public function startElement($parser, $name, /*array*/ $attributes) {
-		if (strcasecmp($name, 'body') != 0) {
-			HTMLDiffer::diffDebug( "Starting $name node.\n" );
-			$this->endWord();
-
-			$newNode = new TagNode($this->currentParent, $name, $attributes);
-			$this->currentParent->children[] = $newNode;
-			$this->currentParent = $newNode;
-			$this->lastSibling = new DummyNode();
-			if ($this->whiteSpaceBeforeThis && !in_array(strtolower($this->currentParent->qName),TagNode::$blocks)) {
-				$this->currentParent->whiteBefore = true;
-			}
-			$this->whiteSpaceBeforeThis = false;
-			if(strcasecmp($name, 'pre') == 0) {
-				$this->notInPre = false;
-			}
-		}
-	}
-
-	public function endElement($parser, $name) {
-		if(strcasecmp($name, 'body') != 0) {
-			HTMLDiffer::diffDebug( "Ending $name node.\n");
-			if (0 == strcasecmp($name,'img')) {
-				// Insert a dummy leaf for the image
-				$img = new ImageNode($this->currentParent, $this->currentParent->attributes);
-				$this->currentParent->children[] = $img;
-				$img->whiteBefore = $this->whiteSpaceBeforeThis;
-				$this->lastSibling = $img;
-				$this->textNodes[] = $img;
-			}
-			$this->endWord();
-			if (!in_array(strtolower($this->currentParent->qName),TagNode::$blocks)) {
-				$this->lastSibling = $this->currentParent;
-			} else {
-				$this->lastSibling = new DummyNode();
-			}
-			$this->currentParent = $this->currentParent->parent;
-			$this->whiteSpaceBeforeThis = false;
-			if (!$this->notInPre && strcasecmp($name, 'pre') == 0) {
-				$this->notInPre = true;
-			}
-		} else {
-			$this->endDocument();
-		}
-	}
-
-	const regex = '/([\s\.\,\"\\\'\(\)\?\:\;\!\{\}\-\+\*\=\_\[\]\&\|\$]{1})/';
-	const whitespace = '/^[\s]{1}$/';
-	const delimiter = '/^[\s\.\,\"\\\'\(\)\?\:\;\!\{\}\-\+\*\=\_\[\]\&\|\$]{1}$/';
-
-	public function characters($parser, $data) {
-		$matches = preg_split(self::regex, $data, -1, PREG_SPLIT_DELIM_CAPTURE);
-
-		foreach($matches as &$word) {
-			if (preg_match(self::whitespace, $word) && $this->notInPre) {
-				$this->endWord();
-				$this->lastSibling->whiteAfter = true;
-				$this->whiteSpaceBeforeThis = true;
-			} else if (preg_match(self::delimiter, $word)) {
-				$this->endWord();
-				$textNode = new TextNode($this->currentParent, $word);
-				$this->currentParent->children[] = $textNode;
-				$textNode->whiteBefore = $this->whiteSpaceBeforeThis;
-				$this->whiteSpaceBeforeThis = false;
-				$this->lastSibling = $textNode;
-				$this->textNodes[] = $textNode;
-			} else {
-				$this->newWord .= $word;
-			}
-		}
-	}
-
-	private function endWord() {
-		if ($this->newWord !== '') {
-			$node = new TextNode($this->currentParent, $this->newWord);
-			$this->currentParent->children[] = $node;
-			$node->whiteBefore = $this->whiteSpaceBeforeThis;
-			$this->whiteSpaceBeforeThis = false;
-			$this->lastSibling = $node;
-			$this->textNodes[] = $node;
-			$this->newWord = "";
-		}
-	}
-
-	public function getDiffLines() {
-		return array_map(array('TextNode','toDiffLine'), $this->textNodes);
-	}
-}
-
-class TextNodeDiffer {
-
-	private $textNodes;
-	public $bodyNode;
-
-	private $oldTextNodes;
-	private $oldBodyNode;
-
-	private $newID = 0;
-
-	private $changedID = 0;
-
-	private $changedIDUsed = false;
-
-	// used to remove the whitespace between a red and green block
-	private $whiteAfterLastChangedPart = false;
-
-	private $deletedID = 0;
-
-	function __construct(DomTreeBuilder $tree, DomTreeBuilder $oldTree) {
-		$this->textNodes = $tree->textNodes;
-		$this->bodyNode = $tree->bodyNode;
-		$this->oldTextNodes = $oldTree->textNodes;
-		$this->oldBodyNode = $oldTree->bodyNode;
-	}
-
-	public function markAsNew($start, $end) {
-		if ($end <= $start) {
-			return;
-		}
-
-		if ($this->whiteAfterLastChangedPart) {
-			$this->textNodes[$start]->whiteBefore = false;
-		}
-
-		for ($i = $start; $i < $end; ++$i) {
-			$mod = new Modification(Modification::ADDED);
-			$mod->id = $this->newID;
-			$this->textNodes[$i]->modification = $mod;
-		}
-		if ($start < $end) {
-			$this->textNodes[$start]->modification->firstOfID = true;
-		}
-		++$this->newID;
-	}
-
-	public function handlePossibleChangedPart($leftstart, $leftend,	$rightstart, $rightend) {
-		$i = $rightstart;
-		$j = $leftstart;
-
-		if ($this->changedIDUsed) {
-			++$this->changedID;
-			$this->changedIDUsed = false;
-		}
-
-		$changes;
-		while ($i < $rightend) {
-			$acthis = new AncestorComparator($this->textNodes[$i]->getParentTree());
-			$acother = new AncestorComparator($this->oldTextNodes[$j]->getParentTree());
-			$result = $acthis->getResult($acother);
-			unset($acthis, $acother);
-
-			if ( $result ) {
-				$mod = new Modification(Modification::CHANGED);
-
-				if (!$this->changedIDUsed) {
-					$mod->firstOfID = true;
-				} else if (!is_null( $result ) && $result !== $this->changes) {
-					++$this->changedID;
-					$mod->firstOfID = true;
-				}
-
-				$mod->changes = $result;
-				$mod->id = $this->changedID;
-
-				$this->textNodes[$i]->modification = $mod;
-				$this->changes = $result;
-				$this->changedIDUsed = true;
-			} else if ($this->changedIDUsed) {
-				++$this->changedID;
-				$this->changedIDUsed = false;
-			}
-			++$i;
-			++$j;
-		}
-	}
-
-	public function markAsDeleted($start, $end, $before) {
-
-		if ($end <= $start) {
-			return;
-		}
-
-		if ($before > 0 && $this->textNodes[$before - 1]->whiteAfter) {
-			$this->whiteAfterLastChangedPart = true;
-		} else {
-			$this->whiteAfterLastChangedPart = false;
-		}
-
-		for ($i = $start; $i < $end; ++$i) {
-			$mod = new Modification(Modification::REMOVED);
-			$mod->id = $this->deletedID;
-
-			// oldTextNodes is used here because we're going to move its deleted
-			// elements to this tree!
-			$this->oldTextNodes[$i]->modification = $mod;
-		}
-		$this->oldTextNodes[$start]->modification->firstOfID = true;
-
-		$root = $this->oldTextNodes[$start]->getLastCommonParent($this->oldTextNodes[$end-1])->parent;
-
-		$junk1 = $junk2 = null;
-		$deletedNodes = $root->getMinimalDeletedSet($this->deletedID, $junk1, $junk2);
-
-		HTMLDiffer::diffDebug( "Minimal set of deleted nodes of size " . count($deletedNodes) . "\n" );
-
-		// Set prevLeaf to the leaf after which the old HTML needs to be
-		// inserted
-		if ($before > 0) {
-			$prevLeaf = $this->textNodes[$before - 1];
-		}
-		// Set nextLeaf to the leaf before which the old HTML needs to be
-		// inserted
-		if ($before < count($this->textNodes)) {
-			$nextLeaf = $this->textNodes[$before];
-		}
-
-		while (count($deletedNodes) > 0) {
-			if (isset($prevLeaf)) {
-				$prevResult = $prevLeaf->getLastCommonParent($deletedNodes[0]);
-			} else {
-				$prevResult = new LastCommonParentResult();
-				$prevResult->parent = $this->bodyNode;
-				$prevResult->indexInLastCommonParent = -1;
-			}
-			if (isset($nextleaf)) {
-				$nextResult = $nextLeaf->getLastCommonParent($deletedNodes[count($deletedNodes) - 1]);
-			} else {
-				$nextResult = new LastCommonParentResult();
-				$nextResult->parent = $this->bodyNode;
-				$nextResult->indexInLastCommonParent = $this->bodyNode->getNbChildren();
-			}
-
-			if ($prevResult->lastCommonParentDepth == $nextResult->lastCommonParentDepth) {
-				// We need some metric to choose which way to add-...
-				if ($deletedNodes[0]->parent === $deletedNodes[count($deletedNodes) - 1]->parent
-						&& $prevResult->parent === $nextResult->parent) {
-					// The difference is not in the parent
-					$prevResult->lastCommonParentDepth = $prevResult->lastCommonParentDepth + 1;
-				} else {
-					// The difference is in the parent, so compare them
-					// now THIS is tricky
-					$distancePrev = $deletedNodes[0]->parent->getMatchRatio($prevResult->parent);
-					$distanceNext = $deletedNodes[count($deletedNodes) - 1]->parent->getMatchRatio($nextResult->parent);
-
-					if ($distancePrev <= $distanceNext) {
-						$prevResult->lastCommonParentDepth = $prevResult->lastCommonParentDepth + 1;
-					} else {
-						$nextResult->lastCommonParentDepth = $nextResult->lastCommonParentDepth + 1;
-					}
-				}
-
-			}
-
-			if ($prevResult->lastCommonParentDepth > $nextResult->lastCommonParentDepth) {
-				// Inserting at the front
-				if ($prevResult->splittingNeeded) {
-					$prevLeaf->parent->splitUntil($prevResult->parent, $prevLeaf, true);
-				}
-				$prevLeaf = $deletedNodes[0]->copyTree();
-				unset($deletedNodes[0]);
-				$deletedNodes = array_values($deletedNodes);
-				$prevLeaf->setParent($prevResult->parent);
-				$prevResult->parent->addChildAbsolute($prevLeaf,$prevResult->indexInLastCommonParent + 1);
-			} else if ($prevResult->lastCommonParentDepth < $nextResult->lastCommonParentDepth) {
-				// Inserting at the back
-				if ($nextResult->splittingNeeded) {
-					$splitOccured = $nextLeaf->parent->splitUntil($nextResult->parent, $nextLeaf, false);
-					if ($splitOccured) {
-						// The place where to insert is shifted one place to the
-						// right
-						$nextResult->indexInLastCommonParent = $nextResult->indexInLastCommonParent + 1;
-					}
-				}
-				$nextLeaf = $deletedNodes[count(deletedNodes) - 1]->copyTree();
-				unset($deletedNodes[count(deletedNodes) - 1]);
-				$deletedNodes = array_values($deletedNodes);
-				$nextLeaf->setParent($nextResult->parent);
-				$nextResult->parent->addChildAbsolute($nextLeaf,$nextResult->indexInLastCommonParent);
-			}
-		}
-		++$this->deletedID;
-	}
-
-	public function expandWhiteSpace() {
-		$this->bodyNode->expandWhiteSpace();
-	}
-
-	public function lengthNew(){
-		return count($this->textNodes);
-	}
-
-	public function lengthOld(){
-		return count($this->oldTextNodes);
-	}
-}
-
-class HTMLDiffer {
-
-	private $output;
-	private static $debug = '';
-
-	function __construct($output) {
-		$this->output = $output;
-	}
-
-	function htmlDiff($from, $to) {
-		wfProfileIn( __METHOD__ );
-		// Create an XML parser
-		$xml_parser = xml_parser_create('');
-
-		$domfrom = new DomTreeBuilder();
-
-		// Set the functions to handle opening and closing tags
-		xml_set_element_handler($xml_parser, array($domfrom, "startElement"), array($domfrom, "endElement"));
-
-		// Set the function to handle blocks of character data
-		xml_set_character_data_handler($xml_parser, array($domfrom, "characters"));
-
-		HTMLDiffer::diffDebug( "Parsing " . strlen($from) . " characters worth of HTML\n" );
-		if (!xml_parse($xml_parser, '<?xml version="1.0" encoding="UTF-8"?>'.Sanitizer::hackDocType().'<body>', false)
-					|| !xml_parse($xml_parser, $from, false)
-					|| !xml_parse($xml_parser, '</body>', true)){
-			$error = xml_error_string(xml_get_error_code($xml_parser));
-			$line = xml_get_current_line_number($xml_parser);
-			HTMLDiffer::diffDebug( "XML error: $error at line $line\n" );
-		}
-		xml_parser_free($xml_parser);
-		unset($from);
-
-		$xml_parser = xml_parser_create('');
-
-		$domto = new DomTreeBuilder();
-
-		// Set the functions to handle opening and closing tags
-		xml_set_element_handler($xml_parser, array($domto, "startElement"), array($domto, "endElement"));
-
-		// Set the function to handle blocks of character data
-		xml_set_character_data_handler($xml_parser, array($domto, "characters"));
-
-		HTMLDiffer::diffDebug( "Parsing " . strlen($to) . " characters worth of HTML\n" );
-		if (!xml_parse($xml_parser, '<?xml version="1.0" encoding="UTF-8"?>'.Sanitizer::hackDocType().'<body>', false)
-		|| !xml_parse($xml_parser, $to, false)
-		|| !xml_parse($xml_parser, '</body>', true)){
-			$error = xml_error_string(xml_get_error_code($xml_parser));
-			$line = xml_get_current_line_number($xml_parser);
-			HTMLDiffer::diffDebug( "XML error: $error at line $line\n" );
-		}
-		xml_parser_free($xml_parser);
-		unset($to);
-
-		$diffengine = new WikiDiff3();
-		$differences = $this->preProcess($diffengine->diff_range($domfrom->getDiffLines(), $domto->getDiffLines()));
-		unset($xml_parser, $diffengine);
-
-		$domdiffer = new TextNodeDiffer($domto, $domfrom);
-
-		$currentIndexLeft = 0;
-		$currentIndexRight = 0;
-		foreach ($differences as &$d) {
-			if ($d->leftstart > $currentIndexLeft) {
-				$domdiffer->handlePossibleChangedPart($currentIndexLeft, $d->leftstart,
-					$currentIndexRight, $d->rightstart);
-			}
-			if ($d->leftlength > 0) {
-				$domdiffer->markAsDeleted($d->leftstart, $d->leftend, $d->rightstart);
-			}
-			$domdiffer->markAsNew($d->rightstart, $d->rightend);
-
-			$currentIndexLeft = $d->leftend;
-			$currentIndexRight = $d->rightend;
-		}
-		$oldLength = $domdiffer->lengthOld();
-		if ($currentIndexLeft < $oldLength) {
-			$domdiffer->handlePossibleChangedPart($currentIndexLeft, $oldLength, $currentIndexRight, $domdiffer->lengthNew());
-		}
-		$domdiffer->expandWhiteSpace();
-		$output = new HTMLOutput('htmldiff', $this->output);
-		$output->parse($domdiffer->bodyNode);
-		wfProfileOut( __METHOD__ );
-	}
-
-	private function preProcess(/*array*/ $differences) {
-		$newRanges = array();
-
-		$nbDifferences = count($differences);
-		for ($i = 0; $i < $nbDifferences; ++$i) {
-			$leftStart = $differences[$i]->leftstart;
-			$leftEnd = $differences[$i]->leftend;
-			$rightStart = $differences[$i]->rightstart;
-			$rightEnd = $differences[$i]->rightend;
-
-			$leftLength = $leftEnd - $leftStart;
-			$rightLength = $rightEnd - $rightStart;
-
-			while ($i + 1 < $nbDifferences && self::score($leftLength,
-						$differences[$i + 1]->leftlength,
-						$rightLength,
-						$differences[$i + 1]->rightlength)
-					> ($differences[$i + 1]->leftstart - $leftEnd)) {
-				$leftEnd = $differences[$i + 1]->leftend;
-				$rightEnd = $differences[$i + 1]->rightend;
-				$leftLength = $leftEnd - $leftStart;
-				$rightLength = $rightEnd - $rightStart;
-				++$i;
-			}
-			$newRanges[] = new RangeDifference($leftStart, $leftEnd, $rightStart, $rightEnd);
-		}
-		return $newRanges;
-	}
-
-	/**
-	 * Heuristic to merge differences for readability.
-	 */
-	public static function score($ll, $nll, $rl, $nrl) {
-		if (($ll == 0 && $nll == 0)
-				|| ($rl == 0 && $nrl == 0)) {
-			return 0;
-		}
-		$numbers = array($ll, $nll, $rl, $nrl);
-		$d = 0;
-		foreach ($numbers as &$number) {
-			while ($number > 3) {
-				$d += 3;
-				$number -= 3;
-				$number *= 0.5;
-			}
-			$d += $number;
-
-		}
-		return $d / (1.5 * count($numbers));
-	}
-
-	/**
-	 * Add to debug output
-	 * @param string $str Debug output
-	 */
-	public static function diffDebug( $str ) {
-		self :: $debug .= $str;
-	}
-	
-	/**
-	 * Get debug output
-	 * @return string
-	 */
-	public static function getDebugOutput() {
-		return self :: $debug;
-	}
-
-}
-
-class TextOnlyComparator {
-
-	public $leafs = array();
-
-	function _construct(TagNode $tree) {
-		$this->addRecursive($tree);
-		$this->leafs = array_map(array('TextNode','toDiffLine'), $this->leafs);
-	}
-
-	private function addRecursive(TagNode $tree) {
-		foreach ($tree->children as &$child) {
-			if ($child instanceof TagNode) {
-				$this->addRecursive($child);
-			} else if ($child instanceof TextNode) {
-				$this->leafs[] = $node;
-			}
-		}
-	}
-
-	public function getMatchRatio(TextOnlyComparator $other) {
-		$nbOthers = count($other->leafs);
-		$nbThis = count($this->leafs);
-		if($nbOthers == 0 || $nbThis == 0){
-			return -log(0);
-		}
-
-		$diffengine = new WikiDiff3(25000, 1.35);
-		$diffengine->diff($this->leafs, $other->leafs);
-
-		$lcsLength = $diffengine->getLcsLength();
-
-		$distanceThis = $nbThis-$lcsLength;
-
-		return (2.0 - $lcsLength/$nbOthers - $lcsLength/$nbThis) / 2.0;
-	}
-}
-
-/**
- * A comparator used when calculating the difference in ancestry of two Nodes.
- */
-class AncestorComparator {
-
-	public $ancestors;
-	public $ancestorsText;
-
-	function __construct(/*array*/ $ancestors) {
-		$this->ancestors = $ancestors;
-		$this->ancestorsText = array_map(array('TagNode','toDiffLine'), $ancestors);
-	}
-
-	public $compareTxt = "";
-
-	public function getResult(AncestorComparator $other) {
-
-		$diffengine = new WikiDiff3(10000, 1.35);
-		$differences = $diffengine->diff_range($other->ancestorsText,$this->ancestorsText);
-
-		if (count($differences) == 0){
-			return null;
-		}
-		$changeTxt = new ChangeTextGenerator($this, $other);
-
-		return $changeTxt->getChanged($differences)->toString();;
-	}
-}
-
-class ChangeTextGenerator {
-
-	private $ancestorComparator;
-	private $other;
-
-	private $factory;
-
-	function __construct(AncestorComparator $ancestorComparator, AncestorComparator $other) {
-		$this->ancestorComparator = $ancestorComparator;
-		$this->other = $other;
-		$this->factory = new TagToStringFactory();
-	}
-
-	public function getChanged(/*array*/ $differences) {
-		$txt = new ChangeText;
-		$rootlistopened = false;
-		if (count($differences) > 1) {
-			$txt->addHtml('<ul class="changelist">');
-			$rootlistopened = true;
-		}
-		$nbDifferences = count($differences);
-		for ($j = 0; $j < $nbDifferences; ++$j) {
-			$d = $differences[$j];
-			$lvl1listopened = false;
-			if ($rootlistopened) {
-				$txt->addHtml('<li>');
-			}
-			if ($d->leftlength + $d->rightlength > 1) {
-				$txt->addHtml('<ul class="changelist">');
-				$lvl1listopened = true;
-			}
-			// left are the old ones
-			for ($i = $d->leftstart; $i < $d->leftend; ++$i) {
-				if ($lvl1listopened){
-					$txt->addHtml('<li>');
-				}
-				// add a bullet for a old tag
-				$this->addTagOld($txt, $this->other->ancestors[$i]);
-				if ($lvl1listopened){
-					$txt->addHtml('</li>');
-				}
-			}
-			// right are the new ones
-			for ($i = $d->rightstart; $i < $d->rightend; ++$i) {
-				if ($lvl1listopened){
-					$txt->addHtml('<li>');
-				}
-				// add a bullet for a new tag
-				$this->addTagNew($txt, $this->ancestorComparator->ancestors[$i]);
-
-				if ($lvl1listopened){
-					$txt->addHtml('</li>');
-				}
-			}
-			if ($lvl1listopened) {
-				$txt->addHtml('</ul>');
-			}
-			if ($rootlistopened) {
-				$txt->addHtml('</li>');
-			}
-		}
-		if ($rootlistopened) {
-			$txt->addHtml('</ul>');
-		}
-		return $txt;
-	}
-
-	private function addTagOld(ChangeText $txt, TagNode $ancestor) {
-		$this->factory->create($ancestor)->getRemovedDescription($txt);
-	}
-
-	private function addTagNew(ChangeText $txt, TagNode $ancestor) {
-		$this->factory->create($ancestor)->getAddedDescription($txt);
-	}
-}
-
-class ChangeText {
-
-	private $txt = "";
-
-	public function addHtml($s) {
-		$this->txt .= $s;
-	}
-
-	public function toString() {
-		return $this->txt;
-	}
-}
-
-class TagToStringFactory {
-
-	private static $containerTags = array('html', 'body', 'p', 'blockquote',
-		'h1', 'h2', 'h3', 'h4', 'h5', 'pre', 'div', 'ul', 'ol', 'li',
-		'table', 'tbody', 'tr', 'td', 'th', 'br', 'hr', 'code', 'dl',
-		'dt', 'dd', 'input', 'form', 'img', 'span', 'a');
-
-	private static $styleTags = array('i', 'b', 'strong', 'em', 'font',
-		'big', 'del', 'tt', 'sub', 'sup', 'strike');
-
-	const MOVED = 1;
-	const STYLE = 2;
-	const UNKNOWN = 4;
-
-	public function create(TagNode $node) {
-		$sem = $this->getChangeSemantic($node->qName);
-		if (strcasecmp($node->qName,'a') == 0) {
-			return new AnchorToString($node, $sem);
-		}
-		if (strcasecmp($node->qName,'img') == 0) {
-			return new NoContentTagToString($node, $sem);
-		}
-		return new TagToString($node, $sem);
-	}
-
-	protected function getChangeSemantic($qname) {
-		if (in_array(strtolower($qname),self::$containerTags)) {
-			return self::MOVED;
-		}
-		if (in_array(strtolower($qname),self::$styleTags)) {
-			return self::STYLE;
-		}
-		return self::UNKNOWN;
-	}
-}
-
-class TagToString {
-
-	protected $node;
-
-	protected $sem;
-
-	function __construct(TagNode $node, $sem) {
-		$this->node = $node;
-		$this->sem = $sem;
-	}
-
-	public function getRemovedDescription(ChangeText $txt) {
-		$tagDescription = wfMsgExt('diff-' . $this->node->qName, 'parseinline' );
-		if( wfEmptyMsg( 'diff-' . $this->node->qName, $tagDescription ) ){
-			$tagDescription = "&lt;" . $this->node->qName . "&gt;";
-		}
-		if ($this->sem == TagToStringFactory::MOVED) {
-			$txt->addHtml( wfMsgExt( 'diff-movedoutof', 'parseinline', $tagDescription ) );
-		} else if ($this->sem == TagToStringFactory::STYLE) {
-			$txt->addHtml( wfMsgExt( 'diff-styleremoved' , 'parseinline', $tagDescription ) );
-		} else {
-			$txt->addHtml( wfMsgExt( 'diff-removed' , 'parseinline', $tagDescription ) );
-		}
-		$this->addAttributes($txt, $this->node->attributes);
-		$txt->addHtml('.');
-	}
-
-	public function getAddedDescription(ChangeText $txt) {
-		$tagDescription = wfMsgExt('diff-' . $this->node->qName, 'parseinline' );
-		if( wfEmptyMsg( 'diff-' . $this->node->qName, $tagDescription ) ){
-			$tagDescription = "&lt;" . $this->node->qName . "&gt;";
-		}
-		if ($this->sem == TagToStringFactory::MOVED) {
-			$txt->addHtml( wfMsgExt( 'diff-movedto' , 'parseinline', $tagDescription) );
-		} else if ($this->sem == TagToStringFactory::STYLE) {
-			$txt->addHtml( wfMsgExt( 'diff-styleadded', 'parseinline', $tagDescription ) );
-		} else {
-			$txt->addHtml( wfMsgExt( 'diff-added', 'parseinline', $tagDescription ) );
-		}
-		$this->addAttributes($txt, $this->node->attributes);
-		$txt->addHtml('.');
-	}
-
-	protected function addAttributes(ChangeText $txt, array $attributes) {
-		if (count($attributes) < 1) {
-			return;
-		}
-		$firstOne = true;
-		$nbAttributes_min_1 = count($attributes)-1;
-		$keys = array_keys($attributes);
-		for ($i=0;$i<$nbAttributes_min_1;$i++) {
-			$key = $keys[$i];
-			$attr = $attributes[$key];
-			if($firstOne) {
-				$firstOne = false;
-				$txt->addHtml( wfMsgExt('diff-with', 'escapenoentities', $this->translateArgument($key), htmlspecialchars($attr) ) );
-				continue;
-			}
-			$txt->addHtml( wfMsgExt( 'comma-separator', 'escapenoentities' ) .
-				wfMsgExt( 'diff-with-additional', 'escapenoentities',
-				$this->translateArgument( $key ), htmlspecialchars( $attr ) )
-			);
-		}
-
-		if ($nbAttributes_min_1 > 0) {
-			$txt->addHtml( wfMsgExt( 'diff-with-final', 'escapenoentities',
-			$this->translateArgument($keys[$nbAttributes_min_1]),
-			htmlspecialchars($attributes[$keys[$nbAttributes_min_1]]) ) );
-		}
-	}
-
-	protected function translateArgument($name) {
-		$translation = wfMsgExt('diff-' . $name, 'parseinline' );
-		if ( wfEmptyMsg( 'diff-' . $name, $translation ) ) {
-			$translation = "&lt;" . $name . "&gt;";;
-		}
-		return htmlspecialchars( $translation );
-	}
-}
-
-class NoContentTagToString extends TagToString {
-
-	function __construct(TagNode $node, $sem) {
-		parent::__construct($node, $sem);
-	}
-
-	public function getAddedDescription(ChangeText $txt) {
-		$tagDescription = wfMsgExt('diff-' . $this->node->qName, 'parseinline' );
-		if( wfEmptyMsg( 'diff-' . $this->node->qName, $tagDescription ) ){
-			$tagDescription = "&lt;" . $this->node->qName . "&gt;";
-		}
-		$txt->addHtml( wfMsgExt('diff-changedto', 'parseinline', $tagDescription ) );
-		$this->addAttributes($txt, $this->node->attributes);
-		$txt->addHtml('.');
-	}
-
-	public function getRemovedDescription(ChangeText $txt) {
-		$tagDescription = wfMsgExt('diff-' . $this->node->qName, 'parseinline' );
-		if( wfEmptyMsg( 'diff-' . $this->node->qName, $tagDescription ) ){
-			$tagDescription = "&lt;" . $this->node->qName . "&gt;";
-		}
-		$txt->addHtml( wfMsgExt('diff-changedfrom', 'parseinline', $tagDescription ) );
-		$this->addAttributes($txt, $this->node->attributes);
-		$txt->addHtml('.');
-	}
-}
-
-class AnchorToString extends TagToString {
-
-	function __construct(TagNode $node, $sem) {
-		parent::__construct($node, $sem);
-	}
-
-	protected function addAttributes(ChangeText $txt, array $attributes) {
-		if (array_key_exists('href', $attributes)) {
-			$txt->addHtml(' ' . wfMsgExt( 'diff-withdestination', 'parseinline', htmlspecialchars($attributes['href']) ) );
-			unset($attributes['href']);
-		}
-		parent::addAttributes($txt, $attributes);
-	}
-}
-
-/**
- * Takes a branch root and creates an HTML file for it.
- */
-class HTMLOutput{
-
-	private $prefix;
-	private $handler;
-
-	function __construct($prefix, $handler) {
-		$this->prefix = $prefix;
-		$this->handler = $handler;
-	}
-
-	public function parse(TagNode $node) {
-		$handler = &$this->handler;
-
-		if (strcasecmp($node->qName, 'img') != 0 && strcasecmp($node->qName, 'body') != 0) {
-			$handler->startElement($node->qName, $node->attributes);
-		}
-
-		$newStarted = false;
-		$remStarted = false;
-		$changeStarted = false;
-		$changeTXT = '';
-
-		foreach ($node->children as &$child) {
-			if ($child instanceof TagNode) {
-				if ($newStarted) {
-					$handler->endElement('span');
-					$newStarted = false;
-				} else if ($changeStarted) {
-					$handler->endElement('span');
-					$changeStarted = false;
-				} else if ($remStarted) {
-					$handler->endElement('span');
-					$remStarted = false;
-				}
-				$this->parse($child);
-			} else if ($child instanceof TextNode) {
-				$mod = $child->modification;
-
-				if ($newStarted && ($mod->type != Modification::ADDED || $mod->firstOfID)) {
-					$handler->endElement('span');
-					$newStarted = false;
-				} else if ($changeStarted && ($mod->type != Modification::CHANGED
-						|| $mod->changes != $changeTXT || $mod->firstOfID)) {
-					$handler->endElement('span');
-					$changeStarted = false;
-				} else if ($remStarted && ($mod->type != Modification::REMOVED || $mod ->firstOfID)) {
-					$handler->endElement('span');
-					$remStarted = false;
-				}
-
-				// no else because a removed part can just be closed and a new
-				// part can start
-				if (!$newStarted && $mod->type == Modification::ADDED) {
-					$attrs = array('class' => 'diff-html-added');
-					if ($mod->firstOfID) {
-						$attrs['id'] = "added-{$this->prefix}-{$mod->id}";
-					}
-					$handler->startElement('span', $attrs);
-					$newStarted = true;
-				} else if (!$changeStarted && $mod->type == Modification::CHANGED) {
-					$attrs = array('class' => 'diff-html-changed');
-					if ($mod->firstOfID) {
-						$attrs['id'] = "changed-{$this->prefix}-{$mod->id}";
-					}
-					$handler->startElement('span', $attrs);
-
-					//tooltip
-					$handler->startElement('span', array('class' => 'tip'));
-					$handler->html($mod->changes);
-					$handler->endElement('span');
-
-					$changeStarted = true;
-					$changeTXT = $mod->changes;
-				} else if (!$remStarted && $mod->type == Modification::REMOVED) {
-					$attrs = array('class'=>'diff-html-removed');
-					if ($mod->firstOfID) {
-						$attrs['id'] = "removed-{$this->prefix}-{$mod->id}";
-					}
-					$handler->startElement('span', $attrs);
-					$remStarted = true;
-				}
-
-				$chars = $child->text;
-
-				if ($child instanceof ImageNode) {
-					$this->writeImage($child);
-				} else {
-					$handler->characters($chars);
-				}
-			}
-		}
-
-		if ($newStarted) {
-			$handler->endElement('span');
-			$newStarted = false;
-		} else if ($changeStarted) {
-			$handler->endElement('span');
-			$changeStarted = false;
-		} else if ($remStarted) {
-			$handler->endElement('span');
-			$remStarted = false;
-		}
-
-		if (strcasecmp($node->qName, 'img') != 0
-				&& strcasecmp($node->qName, 'body') != 0) {
-			$handler->endElement($node->qName);
-		}
-	}
-
-	private function writeImage(ImageNode  $imgNode) {
-		$attrs = $imgNode->attributes;
-		$this->handler->startElement('img', $attrs);
-		$this->handler->endElement('img');
-	}
-}
-
-class DelegatingContentHandler {
-
-	private $delegate;
-
-	function __construct($delegate) {
-		$this->delegate = $delegate;
-	}
-
-	function startElement($qname, /*array*/ $arguments) {
-		$this->delegate->addHtml(Xml::openElement($qname, $arguments));
-	}
-
-	function endElement($qname){
-		$this->delegate->addHtml(Xml::closeElement($qname));
-	}
-
-	function characters($chars){
-		$this->delegate->addHtml(htmlspecialchars($chars));
-	}
-
-	function html($html){
-		$this->delegate->addHtml($html);
-	}
-}
diff --git a/includes/diff/Nodes.php b/includes/diff/Nodes.php
deleted file mode 100644
index 1b1363d49f..0000000000
--- a/includes/diff/Nodes.php
+++ /dev/null
@@ -1,439 +0,0 @@
-<?php
-
-/** Copyright (C) 2008 Guy Van den Broeck <guy@guyvdb.eu>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
- * or see http://www.gnu.org/
- * 
- */
- 
-/**
- * Any element in the DOM tree of an HTML document.
- * @ingroup DifferenceEngine
- */
-class Node {
-
-	public $parent;
-
-	protected $parentTree;
-
-	public $whiteBefore = false;
-
-	public $whiteAfter = false;
-
-	function __construct($parent) {
-		$this->parent = $parent;
-	}
-
-	public function getParentTree() {
-		if (!isset($this->parentTree)) {
-			if (!is_null($this->parent)) {
-				$this->parentTree = $this->parent->getParentTree();
-				$this->parentTree[] = $this->parent;
-			} else {
-				$this->parentTree = array();
-			}
-		}
-		return $this->parentTree;
-	}
-
-	public function getLastCommonParent(Node $other) {
-		$result = new LastCommonParentResult();
-
-		$myParents = $this->getParentTree();
-		$otherParents = $other->getParentTree();
-
-		$i = 1;
-		$isSame = true;
-		$nbMyParents = count($myParents);
-		$nbOtherParents = count($otherParents);
-		while ($isSame && $i < $nbMyParents && $i < $nbOtherParents) {
-			if (!$myParents[$i]->openingTag === $otherParents[$i]->openingTag) {
-				$isSame = false;
-			} else {
-				// After a while, the index i-1 must be the last common parent
-				$i++;
-			}
-		}
-
-		$result->lastCommonParentDepth = $i - 1;
-		$result->parent = $myParents[$i - 1];
-
-		if (!$isSame || $nbMyParents > $nbOtherParents) {
-			// Not all tags matched, or all tags matched but
-			// there are tags left in this tree
-			$result->indexInLastCommonParent = $myParents[$i - 1]->getIndexOf($myParents[$i]);
-			$result->splittingNeeded = true;
-		} else if ($nbMyParents <= $nbOtherParents) {
-			$result->indexInLastCommonParent = $myParents[$i - 1]->getIndexOf($this);
-		}
-		return $result;
-	}
-
-	public function setParent($parent) {
-		$this->parent = $parent;
-		unset($this->parentTree);
-	}
-
-	public function inPre() {
-		$tree = $this->getParentTree();
-		foreach ($tree as &$ancestor) {
-			if ($ancestor->isPre()) {
-				return true;
-			}
-		}
-		return false;
-	}
-}
-
-/**
- * Node that can contain other nodes. Represents an HTML tag.
- * @ingroup DifferenceEngine
- */
-class TagNode extends Node {
-
-	public $children = array();
-
-	public $qName;
-
-	public $attributes = array();
-
-	public $openingTag;
-
-	function __construct($parent, $qName, /*array*/ $attributes) {
-		parent::__construct($parent);
-		$this->qName = strtolower($qName);
-		foreach($attributes as $key => &$value){
-			$this->attributes[strtolower($key)] = $value;
-		}
-		return $this->openingTag = Xml::openElement($this->qName, $this->attributes);
-	}
-
-	public function addChildAbsolute(Node $node, $index) {
-		array_splice($this->children, $index, 0, array($node));
-	}
-
-	public function getIndexOf(Node $child) {
-		// don't trust array_search with objects
-		foreach ($this->children as $key => &$value){
-			if ($value === $child) {
-				return $key;
-			}
-		}
-		return null;
-	}
-
-	public function getNbChildren() {
-		return count($this->children);
-	}
-
-	public function getMinimalDeletedSet($id, &$allDeleted, &$somethingDeleted) {
-		$nodes = array();
-
-		$allDeleted = false;
-		$somethingDeleted = false;
-		$hasNonDeletedDescendant = false;
-
-		if (empty($this->children)) {
-			return $nodes;
-		}
-
-		foreach ($this->children as &$child) {
-			$allDeleted_local = false;
-			$somethingDeleted_local = false;
-			$childrenChildren = $child->getMinimalDeletedSet($id, $allDeleted_local, $somethingDeleted_local);
-			if ($somethingDeleted_local) {
-				$nodes = array_merge($nodes, $childrenChildren);
-				$somethingDeleted = true;
-			}
-			if (!$allDeleted_local) {
-				$hasNonDeletedDescendant = true;
-			}
-		}
-		if (!$hasNonDeletedDescendant) {
-			$nodes = array($this);
-			$allDeleted = true;
-		}
-		return $nodes;
-	}
-
-	public function splitUntil(TagNode $parent, Node $split, $includeLeft) {
-		$splitOccured = false;
-		if ($parent !== $this) {
-			$part1 = new TagNode(null, $this->qName, $this->attributes);
-			$part2 = new TagNode(null, $this->qName, $this->attributes);
-			$part1->setParent($this->parent);
-			$part2->setParent($this->parent);
-
-			$onSplit = false;
-			$pastSplit = false;
-			foreach ($this->children as &$child)
-			{
-				if ($child === $split) {
-					$onSplit = true;
-				}
-				if(!$pastSplit || ($onSplit && $includeLeft)) {
-					$child->setParent($part1);
-					$part1->children[] = $child;
-				} else {
-					$child->setParent($part2);
-					$part2->children[] = $child;
-				}
-				if ($onSplit) {
-					$onSplit = false;
-					$pastSplit = true;
-				}
-			}
-			$myindexinparent = $this->parent->getIndexOf($this);
-			if (!empty($part1->children)) {
-				$this->parent->addChildAbsolute($part1, $myindexinparent);
-			}
-			if (!empty($part2->children)) {
-				$this->parent->addChildAbsolute($part2, $myindexinparent);
-			}
-			if (!empty($part1->children) && !empty($part2->children)) {
-				$splitOccured = true;
-			}
-
-			$this->parent->removeChild($myindexinparent);
-
-			if ($includeLeft) {
-				$this->parent->splitUntil($parent, $part1, $includeLeft);
-			} else {
-				$this->parent->splitUntil($parent, $part2, $includeLeft);
-			}
-		}
-		return $splitOccured;
-
-	}
-
-	private function removeChild($index) {
-		unset($this->children[$index]);
-		$this->children = array_values($this->children);
-	}
-
-	public static $blocks = array('html', 'body','p','blockquote', 'h1',
-		'h2', 'h3', 'h4', 'h5', 'pre', 'div', 'ul', 'ol', 'li', 'table',
-		'tbody', 'tr', 'td', 'th', 'br');
-
-	public function copyTree() {
-		$newThis = new TagNode(null, $this->qName, $this->attributes);
-		$newThis->whiteBefore = $this->whiteBefore;
-		$newThis->whiteAfter = $this->whiteAfter;
-		foreach ($this->children as &$child) {
-			$newChild = $child->copyTree();
-			$newChild->setParent($newThis);
-			$newThis->children[] = $newChild;
-		}
-		return $newThis;
-	}
-
-	public function getMatchRatio(TagNode $other) {
-		$txtComp = new TextOnlyComparator($other);
-		return $txtComp->getMatchRatio(new TextOnlyComparator($this));
-	}
-
-	public function expandWhiteSpace() {
-		$shift = 0;
-		$spaceAdded = false;
-
-		$nbOriginalChildren = $this->getNbChildren();
-		for ($i = 0; $i < $nbOriginalChildren; ++$i) {
-			$child = $this->children[$i + $shift];
-
-			if ($child instanceof TagNode) {
-				if (!$child->isPre()) {
-					$child->expandWhiteSpace();
-				}
-			}
-			if (!$spaceAdded && $child->whiteBefore) {
-				$ws = new WhiteSpaceNode(null, ' ', $child->getLeftMostChild());
-				$ws->setParent($this);
-				$this->addChildAbsolute($ws,$i + ($shift++));
-			}
-			if ($child->whiteAfter) {
-				$ws = new WhiteSpaceNode(null, ' ', $child->getRightMostChild());
-				$ws->setParent($this);
-				$this->addChildAbsolute($ws,$i + 1 + ($shift++));
-				$spaceAdded = true;
-			} else {
-				$spaceAdded = false;
-			}
-
-		}
-	}
-
-	public function getLeftMostChild() {
-		if (empty($this->children)) {
-			return $this;
-		}
-		return $this->children[0]->getLeftMostChild();
-	}
-
-	public function getRightMostChild() {
-		if (empty($this->children)) {
-			return $this;
-		}
-		return $this->children[$this->getNbChildren() - 1]->getRightMostChild();
-	}
-
-	public function isPre() {
-		return 0 == strcasecmp($this->qName,'pre');
-	}
-
-	public static function toDiffLine(TagNode $node) {
-		return $node->openingTag;
-	}
-}
-
-/**
- * Represents a piece of text in the HTML file.
- * @ingroup DifferenceEngine
- */
-class TextNode extends Node {
-
-	public $text;
-
-	public $modification;
-
-	function __construct($parent, $text) {
-		parent::__construct($parent);
-		$this->modification = new Modification(Modification::NONE);
-		$this->text = $text;
-	}
-
-	public function copyTree() {
-		$clone = clone $this;
-		$clone->setParent(null);
-		return $clone;
-	}
-
-	public function getLeftMostChild() {
-		return $this;
-	}
-
-	public function getRightMostChild() {
-		return $this;
-	}
-
-	public function getMinimalDeletedSet($id, &$allDeleted, &$somethingDeleted) {
-		if ($this->modification->type == Modification::REMOVED
-					&& $this->modification->id == $id){
-			$somethingDeleted = true;
-			$allDeleted = true;
-			return array($this);
-		}
-		return array();
-	}
-
-	public function isSameText($other) {
-		if (is_null($other) || ! $other instanceof TextNode) {
-			return false;
-		}
-		return str_replace('\n', ' ',$this->text) === str_replace('\n', ' ',$other->text);
-	}
-
-	public static function toDiffLine(TextNode $node) {
-		return str_replace('\n', ' ',$node->text);
-	}
-}
-
-/**
- * @todo Document
- * @ingroup DifferenceEngine
- */
-class WhiteSpaceNode extends TextNode {
-
-	function __construct($parent, $s, Node $like = null) {
-		parent::__construct($parent, $s);
-		if(!is_null($like) && $like instanceof TextNode) {
-			$newModification = clone $like->modification;
-			$newModification->firstOfID = false;
-			$this->modification = $newModification;
-		}
-	}
-}
-
-/**
- * Represents the root of a HTML document.
- * @ingroup DifferenceEngine
- */
-class BodyNode extends TagNode {
-
-	function __construct() {
-		parent::__construct(null, 'body', array());
-	}
-
-	public function copyTree() {
-		$newThis = new BodyNode();
-		foreach ($this->children as &$child) {
-			$newChild = $child->copyTree();
-			$newChild->setParent($newThis);
-			$newThis->children[] = $newChild;
-		}
-		return $newThis;
-	}
-
-	public function getMinimalDeletedSet($id, &$allDeleted, &$somethingDeleted) {
-		$nodes = array();
-		foreach ($this->children as &$child) {
-			$childrenChildren = $child->getMinimalDeletedSet($id,
-						$allDeleted, $somethingDeleted);
-			$nodes = array_merge($nodes, $childrenChildren);
-		}
-		return $nodes;
-	}
-
-}
-
-/**
- * Represents an image in HTML. Even though images do not contain any text they
- * are independent visible objects on the page. They are logically a TextNode.
- * @ingroup DifferenceEngine
- */
-class ImageNode extends TextNode {
-
-	public $attributes;
-
-	function __construct(TagNode $parent, /*array*/ $attrs) {
-		if(!array_key_exists('src', $attrs)) {
-			HTMLDiffer::diffDebug( "Image without a source\n" );
-			parent::__construct($parent, '<img></img>');
-		}else{
-			parent::__construct($parent, '<img>' . strtolower($attrs['src']) . '</img>');
-		}
-		$this->attributes = $attrs;
-	}
-
-	public function isSameText($other) {
-		if (is_null($other) || ! $other instanceof ImageNode) {
-			return false;
-		}
-		return $this->text === $other->text;
-	}
-
-}
-
-/**
- * No-op node
- * @ingroup DifferenceEngine
- */
-class DummyNode extends Node {
-
-	function __construct() {
-		// no op
-	}
-
-}
diff --git a/languages/messages/MessagesEn.php b/languages/messages/MessagesEn.php
index b3eaebb3f8..9af8891e63 100644
--- a/languages/messages/MessagesEn.php
+++ b/languages/messages/MessagesEn.php
@@ -1563,64 +1563,8 @@ Note that using the navigation links will reset this column.',
 'lineno'                   => 'Line $1:',
 'compareselectedversions'  => 'Compare selected revisions',
 'showhideselectedversions' => 'Show/hide selected revisions',
-'visualcomparison'         => 'Visual comparison',
-'wikicodecomparison'       => 'Wikitext comparison',
 'editundo'                 => 'undo',
 'diff-multi'               => '({{PLURAL:$1|One intermediate revision|$1 intermediate revisions}} not shown)',
-'diff-movedto'             => 'moved to $1',
-'diff-styleadded'          => '$1 style added',
-'diff-added'               => '$1 added',
-'diff-changedto'           => 'changed to $1',
-'diff-movedoutof'          => 'moved out of $1',
-'diff-styleremoved'        => '$1 style removed',
-'diff-removed'             => '$1 removed',
-'diff-changedfrom'         => 'changed from $1',
-'diff-src'                 => 'source',
-'diff-withdestination'     => 'with destination $1',
-'diff-with'                => '&#32;with $1 $2',
-'diff-with-additional'     => '$1 $2', # only translate this message to other languages if you have to change it
-'diff-with-final'          => '&#32;and $1 $2',
-'diff-width'               => 'width',
-'diff-height'              => 'height',
-'diff-p'                   => "a '''paragraph'''",
-'diff-blockquote'          => "a '''quote'''",
-'diff-h1'                  => "a '''heading (level 1)'''",
-'diff-h2'                  => "a '''heading (level 2)'''",
-'diff-h3'                  => "a '''heading (level 3)'''",
-'diff-h4'                  => "a '''heading (level 4)'''",
-'diff-h5'                  => "a '''heading (level 5)'''",
-'diff-pre'                 => "a '''preformatted block'''",
-'diff-div'                 => "a '''division'''",
-'diff-ul'                  => "an '''unordered list'''",
-'diff-ol'                  => "an '''ordered list'''",
-'diff-li'                  => "a '''list item'''",
-'diff-table'               => "a '''table'''",
-'diff-tbody'               => "a '''table's content'''",
-'diff-tr'                  => "a '''row'''",
-'diff-td'                  => "a '''cell'''",
-'diff-th'                  => "a '''header'''",
-'diff-br'                  => "a '''break'''",
-'diff-hr'                  => "a '''horizontal rule'''",
-'diff-code'                => "a '''computer code block'''",
-'diff-dl'                  => "a '''definition list'''",
-'diff-dt'                  => "a '''definition term'''",
-'diff-dd'                  => "a '''definition'''",
-'diff-input'               => "an '''input'''",
-'diff-form'                => "a '''form'''",
-'diff-img'                 => "an '''image'''",
-'diff-span'                => "a '''span'''",
-'diff-a'                   => "a '''link'''",
-'diff-i'                   => "'''italics'''",
-'diff-b'                   => "'''bold'''",
-'diff-strong'              => "'''strong'''",
-'diff-em'                  => "'''emphasis'''",
-'diff-font'                => "'''font'''",
-'diff-big'                 => "'''big'''",
-'diff-del'                 => "'''deleted'''",
-'diff-tt'                  => "'''fixed width'''",
-'diff-sub'                 => "'''subscript'''",
-'diff-sup'                 => "'''superscript'''",
-'diff-strike'              => "'''strikethrough'''",
 
 # Search results
 'searchresults'                    => 'Search results',
@@ -3276,7 +3220,6 @@ Please try again.',
 'accesskey-preview'                 => 'p', # do not translate or duplicate this message to other languages
 'accesskey-diff'                    => 'v', # do not translate or duplicate this message to other languages
 'accesskey-compareselectedversions' => 'v', # do not translate or duplicate this message to other languages
-'accesskey-visualcomparison'        => 'b', # do not translate or duplicate this message to other languages
 'accesskey-watch'                   => 'w', # do not translate or duplicate this message to other languages
 'accesskey-upload'                  => 's', # do not translate or duplicate this message to other languages
 
@@ -3475,9 +3418,6 @@ $1',
 'previousdiff' => '← Older edit',
 'nextdiff'     => 'Newer edit →',
 
-# Visual comparison
-'visual-comparison' => 'Visual comparison',
-
 # Media information
 'mediawarning'         => "'''Warning''': This file may contain malicious code, by executing it your system may be compromised.<hr />",
 'imagemaxsize'         => "Image size limit:<br />''(for file description pages)''",
diff --git a/maintenance/language/messageTypes.inc b/maintenance/language/messageTypes.inc
index 11fdca71f2..6f3bcc67d0 100644
--- a/maintenance/language/messageTypes.inc
+++ b/maintenance/language/messageTypes.inc
@@ -67,7 +67,6 @@ $wgIgnoredMessages = array(
 	'accesskey-preview',
 	'accesskey-diff',
 	'accesskey-compareselectedversions',
-	'accesskey-visualcomparison',
 	'accesskey-watch',
 	'accesskey-upload',
 	'addsection',
diff --git a/maintenance/language/messages.inc b/maintenance/language/messages.inc
index 9dbaefdb3d..fdff4addc6 100644
--- a/maintenance/language/messages.inc
+++ b/maintenance/language/messages.inc
@@ -766,64 +766,7 @@ $wgMessageStructure = array(
 		'lineno',
 		'compareselectedversions',
 		'showhideselectedversions',
-		'visualcomparison',
-		'wikicodecomparison',
 		'editundo',
-		'diff-multi',
-		'diff-movedto',
-		'diff-styleadded',
-		'diff-added',
-		'diff-changedto',
-		'diff-movedoutof',
-		'diff-styleremoved',
-		'diff-removed',
-		'diff-changedfrom',
-		'diff-src',
-		'diff-withdestination',
-		'diff-with',
-		'diff-with-additional',
-		'diff-with-final',
-		'diff-width',
-		'diff-height',
-		'diff-p',
-		'diff-blockquote',
-		'diff-h1',
-		'diff-h2',
-		'diff-h3',
-		'diff-h4',
-		'diff-h5',
-		'diff-pre',
-		'diff-div',
-		'diff-ul',
-		'diff-ol',
-		'diff-li',
-		'diff-table',
-		'diff-tbody',
-		'diff-tr',
-		'diff-td',
-		'diff-th',
-		'diff-br',
-		'diff-hr',
-		'diff-code',
-		'diff-dl',
-		'diff-dt',
-		'diff-dd',
-		'diff-input',
-		'diff-form',
-		'diff-img',
-		'diff-span',
-		'diff-a',
-		'diff-i',
-		'diff-b',
-		'diff-strong',
-		'diff-em',
-		'diff-font',
-		'diff-big',
-		'diff-del',
-		'diff-tt',
-		'diff-sub',
-		'diff-sup',
-		'diff-strike',
 	),
 	'search' => array(
 		'searchresults',
@@ -2262,7 +2205,6 @@ $wgMessageStructure = array(
 		'accesskey-preview',
 		'accesskey-diff',
 		'accesskey-compareselectedversions',
-		'accesskey-visualcomparison',
 		'accesskey-watch',
 		'accesskey-upload',
 	),
@@ -2454,9 +2396,6 @@ $wgMessageStructure = array(
 		'previousdiff',
 		'nextdiff',
 	),
-	'visual-comparison' => array(
-		'visual-comparison',
-	),
 	'media-info' => array(
 		'mediawarning',
 		'imagemaxsize',
@@ -3304,7 +3243,6 @@ Variants for Chinese language",
 	'variantname-kk'      => 'Variants for Kazakh language',
 	'variantname-ku'      => 'Variants for Kurdish language',
 	'variantname-tg'      => 'Variants for Tajiki language',
-	'visual-comparison'   => 'Visual comparison',
 	'media-info'          => 'Media information',
 	'metadata'            => 'Metadata',
 	'exif'                           => 'EXIF tags',
-- 
2.20.1