includes/diff/DifferenceEngine.php

   1 <?php
   2 /**
   3  * @defgroup DifferenceEngine DifferenceEngine
   4  */
   5
   6 /**
   7  * Constant to indicate diff cache compatibility.
   8  * Bump this when changing the diff formatting in a way that
   9  * fixes important bugs or such to force cached diff views to
  10  * clear.
  11  */
  12 define( 'MW_DIFF_VERSION', '1.11a' );
  13
  14 /**
  15  * @todo document
  16  * @ingroup DifferenceEngine
  17  */
  18 class DifferenceEngine {
  19         /**#@+
  20          * @private
  21          */
  22         var $mOldid, $mNewid, $mTitle;
  23         var $mOldtitle, $mNewtitle, $mPagetitle;
  24         var $mOldtext, $mNewtext;
  25         var $mOldPage, $mNewPage;
  26         var $mRcidMarkPatrolled;
  27         var $mOldRev, $mNewRev;
  28         var $mRevisionsLoaded = false; // Have the revisions been loaded
  29         var $mTextLoaded = 0; // How many text blobs have been loaded, 0, 1 or 2?
  30         var $mCacheHit = false; // Was the diff fetched from cache?
  31         var $htmldiff;
  32
  33         protected $unhide = false;
  34         /**#@-*/
  35
  36         /**
  37          * Constructor
  38          * @param $titleObj Title object that the diff is associated with
  39          * @param $old Integer: old ID we want to show and diff with.
  40          * @param $new String: either 'prev' or 'next'.
  41          * @param $rcid Integer: ??? FIXME (default 0)
  42          * @param $refreshCache boolean If set, refreshes the diff cache
  43          * @param $htmldiff boolean If set, output using HTMLDiff instead of raw wikicode diff
  44          * @param $unhide boolean If set, allow viewing deleted revs
  45          */
  46         function __construct( $titleObj = null, $old = 0, $new = 0, $rcid = 0, $refreshCache = false , $htmldiff = false, $unhide = false ) {
  47                 $this->mTitle = $titleObj;
  48                 wfDebug("DifferenceEngine old '$old' new '$new' rcid '$rcid'\n");
  49
  50                 if ( 'prev' === $new ) {
  51                         # Show diff between revision $old and the previous one.
  52                         # Get previous one from DB.
  53                         $this->mNewid = intval($old);
  54                         $this->mOldid = $this->mTitle->getPreviousRevisionID( $this->mNewid );
  55                 } elseif ( 'next' === $new ) {
  56                         # Show diff between revision $old and the next one.
  57                         # Get next one from DB.
  58                         $this->mOldid = intval($old);
  59                         $this->mNewid = $this->mTitle->getNextRevisionID( $this->mOldid );
  60                         if ( false === $this->mNewid ) {
  61                                 # if no result, NewId points to the newest old revision. The only newer
  62                                 # revision is cur, which is "0".
  63                                 $this->mNewid = 0;
  64                         }
  65                 } else {
  66                         $this->mOldid = intval($old);
  67                         $this->mNewid = intval($new);
  68                         wfRunHooks( 'NewDifferenceEngine', array(&$titleObj, &$this->mOldid, &$this->mNewid, $old, $new) );
  69                 }
  70                 $this->mRcidMarkPatrolled = intval($rcid);  # force it to be an integer
  71                 $this->mRefreshCache = $refreshCache;
  72                 $this->htmldiff = $htmldiff;
  73                 $this->unhide = $unhide;
  74         }
  75
  76         function getTitle() {
  77                 return $this->mTitle;
  78         }
  79
  80         function wasCacheHit() {
  81                 return $this->mCacheHit;
  82         }
  83
  84         function getOldid() {
  85                 return $this->mOldid;
  86         }
  87
  88         function getNewid() {
  89                 return $this->mNewid;
  90         }
  91
  92         function showDiffPage( $diffOnly = false ) {
  93                 global $wgUser, $wgOut, $wgUseExternalEditor, $wgUseRCPatrol, $wgEnableHtmlDiff;
  94                 wfProfileIn( __METHOD__ );
  95
  96
  97                 # If external diffs are enabled both globally and for the user,
  98                 # we'll use the application/x-external-editor interface to call
  99                 # an external diff tool like kompare, kdiff3, etc.
 100                 if($wgUseExternalEditor && $wgUser->getOption('externaldiff')) {
 101                         global $wgInputEncoding,$wgServer,$wgScript,$wgLang;
 102                         $wgOut->disable();
 103                         header ( "Content-type: application/x-external-editor; charset=".$wgInputEncoding );
 104                         $url1=$this->mTitle->getFullURL("action=raw&oldid=".$this->mOldid);
 105                         $url2=$this->mTitle->getFullURL("action=raw&oldid=".$this->mNewid);
 106                         $special=$wgLang->getNsText(NS_SPECIAL);
 107                         $control=<<<CONTROL
 108                         [Process]
 109                         Type=Diff text
 110                         Engine=MediaWiki
 111                         Script={$wgServer}{$wgScript}
 112                         Special namespace={$special}
 113
 114                         [File]
 115                         Extension=wiki
 116                         URL=$url1
 117
 118                         [File 2]
 119                         Extension=wiki
 120                         URL=$url2
 121 CONTROL;
 122                         echo($control);
 123                         return;
 124                 }
 125
 126                 $wgOut->setArticleFlag( false );
 127                 if ( !$this->loadRevisionData() ) {
 128                         $t = $this->mTitle->getPrefixedText();
 129                         $d = wfMsgExt( 'missingarticle-diff', array( 'escape' ), $this->mOldid, $this->mNewid );
 130                         $wgOut->setPagetitle( wfMsg( 'errorpagetitle' ) );
 131                         $wgOut->addWikiMsg( 'missing-article', "<nowiki>$t</nowiki>", $d );
 132                         wfProfileOut( __METHOD__ );
 133                         return;
 134                 }
 135
 136                 wfRunHooks( 'DiffViewHeader', array( $this, $this->mOldRev, $this->mNewRev ) );
 137
 138                 if ( $this->mNewRev->isCurrent() ) {
 139                         $wgOut->setArticleFlag( true );
 140                 }
 141
 142                 # mOldid is false if the difference engine is called with a "vague" query for
 143                 # a diff between a version V and its previous version V' AND the version V
 144                 # is the first version of that article. In that case, V' does not exist.
 145                 if ( $this->mOldid === false ) {
 146                         $this->showFirstRevision();
 147                         $this->renderNewRevision();  // should we respect $diffOnly here or not?
 148                         wfProfileOut( __METHOD__ );
 149                         return;
 150                 }
 151
 152                 $wgOut->suppressQuickbar();
 153
 154                 $oldTitle = $this->mOldPage->getPrefixedText();
 155                 $newTitle = $this->mNewPage->getPrefixedText();
 156                 if( $oldTitle == $newTitle ) {
 157                         $wgOut->setPageTitle( $newTitle );
 158                 } else {
 159                         $wgOut->setPageTitle( $oldTitle . ', ' . $newTitle );
 160                 }
 161                 $wgOut->setSubtitle( wfMsgExt( 'difference', array( 'parseinline' ) ) );
 162                 $wgOut->setRobotPolicy( 'noindex,nofollow' );
 163
 164                 if ( !$this->mOldPage->userCanRead() || !$this->mNewPage->userCanRead() ) {
 165                         $wgOut->loginToUse();
 166                         $wgOut->output();
 167                         $wgOut->disable();
 168                         wfProfileOut( __METHOD__ );
 169                         return;
 170                 }
 171
 172                 $sk = $wgUser->getSkin();
 173
 174                 // Check if page is editable
 175                 $editable = $this->mNewRev->getTitle()->userCan( 'edit' );
 176                 if ( $editable && $this->mNewRev->isCurrent() && $wgUser->isAllowed( 'rollback' ) ) {
 177                         $rollback = '&nbsp;&nbsp;&nbsp;' . $sk->generateRollback( $this->mNewRev );
 178                 } else {
 179                         $rollback = '';
 180                 }
 181
 182                 // Prepare a change patrol link, if applicable
 183                 if( $wgUseRCPatrol && $this->mTitle->userCan('patrol') ) {
 184                         // If we've been given an explicit change identifier, use it; saves time
 185                         if( $this->mRcidMarkPatrolled ) {
 186                                 $rcid = $this->mRcidMarkPatrolled;
 187                                 $rc = RecentChange::newFromId( $rcid );
 188                                 // Already patrolled?
 189                                 $rcid = is_object($rc) && !$rc->getAttribute('rc_patrolled') ? $rcid : 0;
 190                         } else {
 191                                 // Look for an unpatrolled change corresponding to this diff
 192                                 $db = wfGetDB( DB_SLAVE );
 193                                 $change = RecentChange::newFromConds(
 194                                         array(
 195                                         // Add redundant user,timestamp condition so we can use the existing index
 196                                                         'rc_user_text'  => $this->mNewRev->getRawUserText(),
 197                                                         'rc_timestamp'  => $db->timestamp( $this->mNewRev->getTimestamp() ),
 198                                                         'rc_this_oldid' => $this->mNewid,
 199                                                         'rc_last_oldid' => $this->mOldid,
 200                                                         'rc_patrolled'  => 0
 201                                         ),
 202                                         __METHOD__
 203                                 );
 204                                 if( $change instanceof RecentChange ) {
 205                                         $rcid = $change->mAttribs['rc_id'];
 206                                         $this->mRcidMarkPatrolled = $rcid;
 207                                 } else {
 208                                         // None found
 209                                         $rcid = 0;
 210                                 }
 211                         }
 212                         // Build the link
 213                         if( $rcid ) {
 214                                 $patrol = ' <span class="patrollink">[' . $sk->makeKnownLinkObj( $this->mTitle,
 215                                         wfMsgHtml( 'markaspatrolleddiff' ), "action=markpatrolled&rcid={$rcid}" ) . ']</span>';
 216                         } else {
 217                                 $patrol = '';
 218                         }
 219                 } else {
 220                         $patrol = '';
 221                 }
 222
 223                 $diffOnlyArg = '';
 224                 # Carry over 'diffonly' param via navigation links
 225                 if( $diffOnly != $wgUser->getBoolOption('diffonly') ) {
 226                         $diffOnlyArg = '&diffonly='.$diffOnly;
 227                 }
 228                 $htmldiffarg = $this->htmlDiffArgument();
 229                 # Make "previous revision link"
 230                 $prevlink = $sk->makeKnownLinkObj( $this->mTitle, wfMsgHtml( 'previousdiff' ),
 231                         "diff=prev&oldid={$this->mOldid}{$htmldiffarg}{$diffOnlyArg}", '', '', 'id="differences-prevlink"' );
 232                 # Make "next revision link"
 233                 if( $this->mNewRev->isCurrent() ) {
 234                         $nextlink = '&nbsp;';
 235                 } else {
 236                         $nextlink = $sk->makeKnownLinkObj( $this->mTitle, wfMsgHtml( 'nextdiff' ),
 237                                 "diff=next&oldid={$this->mNewid}{$htmldiffarg}{$diffOnlyArg}", '', '', 'id="differences-nextlink"' );
 238                 }
 239
 240                 $oldminor = '';
 241                 $newminor = '';
 242
 243                 if( $this->mOldRev->isMinor() ) {
 244                         $oldminor = Xml::span( wfMsg( 'minoreditletter' ), 'minor' ) . ' ';
 245                 }
 246                 if( $this->mNewRev->isMinor() ) {
 247                         $newminor = Xml::span( wfMsg( 'minoreditletter' ), 'minor' ) . ' ';
 248                 }
 249
 250                 $rdel = ''; $ldel = '';
 251                 if( $wgUser->isAllowed( 'deleterevision' ) ) {
 252                         if( !$this->mOldRev->userCan( Revision::DELETED_RESTRICTED ) ) {
 253                                 // If revision was hidden from sysops
 254                                 $ldel = Xml::tags( 'span', array( 'class'=>'mw-revdelundel-link' ), '('.wfMsgHtml( 'rev-delundel' ).')' );
 255                         } else {
 256                                 $query = array( 'target' => $this->mOldRev->mTitle->getPrefixedDbkey(),
 257                                         'oldid' => $this->mOldRev->getId()
 258                                 );
 259                                 $ldel = $sk->revDeleteLink( $query, $this->mOldRev->isDeleted( Revision::DELETED_RESTRICTED ) );
 260                         }
 261                         $ldel = "&nbsp;&nbsp;&nbsp;$ldel ";
 262                         // We don't currently handle well changing the top revision's settings
 263                         if( $this->mNewRev->isCurrent() ) {
 264                                 $rdel = Xml::tags( 'span', array( 'class'=>'mw-revdelundel-link' ), '('.wfMsgHtml( 'rev-delundel' ).')' );
 265                         } else if( !$this->mNewRev->userCan( Revision::DELETED_RESTRICTED ) ) {
 266                                 // If revision was hidden from sysops
 267                                 $rdel = Xml::tags( 'span', array( 'class'=>'mw-revdelundel-link' ), '('.wfMsgHtml( 'rev-delundel' ).')' );
 268                         } else {
 269                                 $query = array( 'target' =>  $this->mNewRev->mTitle->getPrefixedDbkey(),
 270                                         'oldid' => $this->mNewRev->getId()
 271                                 );
 272                                 $rdel = $sk->revDeleteLink( $query, $this->mNewRev->isDeleted( Revision::DELETED_RESTRICTED ) );
 273                         }
 274                         $rdel = "&nbsp;&nbsp;&nbsp;$rdel ";
 275                 }
 276
 277                 $oldHeader = '<div id="mw-diff-otitle1"><strong>'.$this->mOldtitle.'</strong></div>' .
 278                         '<div id="mw-diff-otitle2">' . $sk->revUserTools( $this->mOldRev, !$this->unhide ) . "</div>" .
 279                         '<div id="mw-diff-otitle3">' . $oldminor . $sk->revComment( $this->mOldRev, !$diffOnly, !$this->unhide ).$ldel."</div>" .
 280                         '<div id="mw-diff-otitle4">' . $prevlink .'</div>';
 281                 $newHeader = '<div id="mw-diff-ntitle1"><strong>'.$this->mNewtitle.'</strong></div>' .
 282                         '<div id="mw-diff-ntitle2">' . $sk->revUserTools( $this->mNewRev, !$this->unhide ) . " $rollback</div>" .
 283                         '<div id="mw-diff-ntitle3">' . $newminor . $sk->revComment( $this->mNewRev, !$diffOnly, !$this->unhide ).$rdel."</div>" .
 284                         '<div id="mw-diff-ntitle4">' . $nextlink . $patrol . '</div>';
 285
 286                 # Check if this user can see the revisions
 287                 $allowed = $this->mOldRev->userCan(Revision::DELETED_TEXT)
 288                         && $this->mNewRev->userCan(Revision::DELETED_TEXT);
 289                 $deleted = $this->mOldRev->isDeleted(Revision::DELETED_TEXT)
 290                         || $this->mNewRev->isDeleted(Revision::DELETED_TEXT);
 291                 # Output the diff if allowed...
 292                 if( $deleted && (!$this->unhide || !$allowed) ) {
 293                         $this->showDiffStyle();
 294                         $multi = $this->getMultiNotice();
 295                         $wgOut->addHTML( $this->addHeader( '', $oldHeader, $newHeader, $multi ) );
 296                         if( !$allowed ) {
 297                                 # Give explanation for why revision is not visible
 298                                 $wgOut->wrapWikiMsg( "<div class='mw-warning plainlinks'>\n$1</div>\n",
 299                                         array( 'rev-deleted-no-diff' ) );
 300                         } else {
 301                                 # Give explanation and add a link to view the diff...
 302                                 $link = $this->mTitle->getFullUrl( "diff={$this->mNewid}&oldid={$this->mOldid}".
 303                                         '&unhide=1&token='.urlencode( $wgUser->editToken($this->mNewid) ) );
 304                                 $wgOut->wrapWikiMsg( "<div class='mw-warning plainlinks'>\n$1</div>\n",
 305                                         array( 'rev-deleted-unhide-diff', $link ) );
 306                         }
 307                 } else if( $wgEnableHtmlDiff && $this->htmldiff ) {
 308                         $multi = $this->getMultiNotice();
 309                         $wgOut->addHTML('<div class="diff-switchtype">'.$sk->makeKnownLinkObj( $this->mTitle, wfMsgHtml( 'wikicodecomparison' ),
 310                                 'diff='.$this->mNewid.'&oldid='.$this->mOldid.'&htmldiff=0', '', '', 'id="differences-switchtype"' ).'</div>');
 311                         $wgOut->addHTML( $this->addHeader( '', $oldHeader, $newHeader, $multi ) );
 312                         $this->renderHtmlDiff();
 313                 } else {
 314                         if( $wgEnableHtmlDiff ) {
 315                                 $wgOut->addHTML('<div class="diff-switchtype">'.$sk->makeKnownLinkObj( $this->mTitle, wfMsgHtml( 'visualcomparison' ),
 316                                         'diff='.$this->mNewid.'&oldid='.$this->mOldid.'&htmldiff=1', '', '', 'id="differences-switchtype"' ).'</div>');
 317                         }
 318                         $this->showDiff( $oldHeader, $newHeader );
 319                         if( !$diffOnly ) {
 320                                 $this->renderNewRevision();
 321                         }
 322                 }
 323                 wfProfileOut( __METHOD__ );
 324         }
 325
 326         /**
 327          * Show the new revision of the page.
 328          */
 329         function renderNewRevision() {
 330                 global $wgOut, $wgUser;
 331                 wfProfileIn( __METHOD__ );
 332
 333                 $wgOut->addHTML( "<hr /><h2>{$this->mPagetitle}</h2>\n" );
 334                 # Add deleted rev tag if needed
 335                 if( !$this->mNewRev->userCan(Revision::DELETED_TEXT) ) {
 336                         $wgOut->wrapWikiMsg( "<div class='mw-warning plainlinks'>\n$1</div>\n", 'rev-deleted-text-permission' );
 337                 } else if( $this->mNewRev->isDeleted(Revision::DELETED_TEXT) ) {
 338                         $wgOut->wrapWikiMsg( "<div class='mw-warning plainlinks'>\n$1</div>\n", 'rev-deleted-text-view' );
 339                 }
 340
 341                 if( !$this->mNewRev->isCurrent() ) {
 342                         $oldEditSectionSetting = $wgOut->parserOptions()->setEditSection( false );
 343                 }
 344
 345                 $this->loadNewText();
 346                 if( is_object( $this->mNewRev ) ) {
 347                         $wgOut->setRevisionId( $this->mNewRev->getId() );
 348                 }
 349
 350                 if( $this->mTitle->isCssJsSubpage() || $this->mTitle->isCssOrJsPage() ) {
 351                         // Stolen from Article::view --AG 2007-10-11
 352                         // Give hooks a chance to customise the output
 353                         if( wfRunHooks( 'ShowRawCssJs', array( $this->mNewtext, $this->mTitle, $wgOut ) ) ) {
 354                                 // Wrap the whole lot in a <pre> and don't parse
 355                                 $m = array();
 356                                 preg_match( '!\.(css|js)$!u', $this->mTitle->getText(), $m );
 357                                 $wgOut->addHTML( "<pre class=\"mw-code mw-{$m[1]}\" dir=\"ltr\">\n" );
 358                                 $wgOut->addHTML( htmlspecialchars( $this->mNewtext ) );
 359                                 $wgOut->addHTML( "\n</pre>\n" );
 360                         }
 361                 } else {
 362                         $wgOut->addWikiTextTidy( $this->mNewtext );
 363                 }
 364
 365                 if( is_object( $this->mNewRev ) && !$this->mNewRev->isCurrent() ) {
 366                         $wgOut->parserOptions()->setEditSection( $oldEditSectionSetting );
 367                 }
 368                 # Add redundant patrol link on bottom...
 369                 if( $this->mRcidMarkPatrolled && $this->mTitle->quickUserCan('patrol') ) {
 370                         $sk = $wgUser->getSkin();
 371                         $wgOut->addHTML(
 372                                 "<div class='patrollink'>[" . $sk->makeKnownLinkObj( $this->mTitle,
 373                                         wfMsgHtml( 'markaspatrolleddiff' ), "action=markpatrolled&rcid={$this->mRcidMarkPatrolled}" ) .
 374                                 ']</div>'
 375                          );
 376                 }
 377
 378                 wfProfileOut( __METHOD__ );
 379         }
 380
 381
 382         function renderHtmlDiff() {
 383                 global $wgOut, $wgTitle, $wgParser, $wgDebugComments;
 384                 wfProfileIn( __METHOD__ );
 385
 386                 $this->showDiffStyle();
 387
 388                 $wgOut->addHTML( '<h2>'.wfMsgHtml( 'visual-comparison' )."</h2>\n" );
 389                 #add deleted rev tag if needed
 390                 if( !$this->mNewRev->userCan(Revision::DELETED_TEXT) ) {
 391                         $wgOut->wrapWikiMsg( "<div class='mw-warning plainlinks'>\n$1</div>\n", 'rev-deleted-text-permission' );
 392                 } else if( $this->mNewRev->isDeleted(Revision::DELETED_TEXT) ) {
 393                         $wgOut->wrapWikiMsg( "<div class='mw-warning plainlinks'>\n$1</div>\n", 'rev-deleted-text-view' );
 394                 }
 395
 396                 if( !$this->mNewRev->isCurrent() ) {
 397                         $oldEditSectionSetting = $wgOut->parserOptions()->setEditSection( false );
 398                 }
 399
 400                 $this->loadText();
 401
 402                 // Old revision
 403                 if( is_object( $this->mOldRev ) ) {
 404                         $wgOut->setRevisionId( $this->mOldRev->getId() );
 405                 }
 406
 407                 $popts = $wgOut->parserOptions();
 408                 $oldTidy = $popts->setTidy( true );
 409                 $popts->setEditSection( false );
 410
 411                 $parserOutput = $wgParser->parse( $this->mOldtext, $wgTitle, $popts, true, true, $wgOut->getRevisionId() );
 412                 $popts->setTidy( $oldTidy );
 413
 414                 //only for new?
 415                 //$wgOut->addParserOutputNoText( $parserOutput );
 416                 $oldHtml = $parserOutput->getText();
 417                 wfRunHooks( 'OutputPageBeforeHTML', array( &$wgOut, &$oldHtml ) );
 418
 419                 // New revision
 420                 if( is_object( $this->mNewRev ) ) {
 421                         $wgOut->setRevisionId( $this->mNewRev->getId() );
 422                 }
 423
 424                 $popts = $wgOut->parserOptions();
 425                 $oldTidy = $popts->setTidy( true );
 426
 427                 $parserOutput = $wgParser->parse( $this->mNewtext, $wgTitle, $popts, true, true, $wgOut->getRevisionId() );
 428                 $popts->setTidy( $oldTidy );
 429
 430                 $wgOut->addParserOutputNoText( $parserOutput );
 431                 $newHtml = $parserOutput->getText();
 432                 wfRunHooks( 'OutputPageBeforeHTML', array( &$wgOut, &$newHtml ) );
 433
 434                 unset($parserOutput, $popts);
 435
 436                 $differ = new HTMLDiffer(new DelegatingContentHandler($wgOut));
 437                 $differ->htmlDiff($oldHtml, $newHtml);
 438                 if ( $wgDebugComments ) {
 439                         $wgOut->addHTML( "\n<!-- HtmlDiff Debug Output:\n" . HTMLDiffer::getDebugOutput() . " End Debug -->" );
 440                 }
 441
 442                 wfProfileOut( __METHOD__ );
 443         }
 444
 445         /**
 446          * Show the first revision of an article. Uses normal diff headers in
 447          * contrast to normal "old revision" display style.
 448          */
 449         function showFirstRevision() {
 450                 global $wgOut, $wgUser;
 451                 wfProfileIn( __METHOD__ );
 452
 453                 # Get article text from the DB
 454                 #
 455                 if ( ! $this->loadNewText() ) {
 456                         $t = $this->mTitle->getPrefixedText();
 457                         $d = wfMsgExt( 'missingarticle-diff', array( 'escape' ), $this->mOldid, $this->mNewid );
 458                         $wgOut->setPagetitle( wfMsg( 'errorpagetitle' ) );
 459                         $wgOut->addWikiMsg( 'missing-article', "<nowiki>$t</nowiki>", $d );
 460                         wfProfileOut( __METHOD__ );
 461                         return;
 462                 }
 463                 if ( $this->mNewRev->isCurrent() ) {
 464                         $wgOut->setArticleFlag( true );
 465                 }
 466
 467                 # Check if user is allowed to look at this page. If not, bail out.
 468                 #
 469                 if ( !$this->mTitle->userCanRead() ) {
 470                         $wgOut->loginToUse();
 471                         $wgOut->output();
 472                         wfProfileOut( __METHOD__ );
 473                         throw new MWException("Permission Error: you do not have access to view this page");
 474                 }
 475
 476                 # Prepare the header box
 477                 #
 478                 $sk = $wgUser->getSkin();
 479
 480                 $next = $this->mTitle->getNextRevisionID( $this->mNewid );
 481                 if( !$next ) {
 482                         $nextlink = '';
 483                 } else {
 484                         $nextlink = '<br/>' . $sk->makeKnownLinkObj( $this->mTitle, wfMsgHtml( 'nextdiff' ),
 485                                 'diff=next&oldid=' . $this->mNewid.$this->htmlDiffArgument(), '', '', 'id="differences-nextlink"' );
 486                 }
 487                 $header = "<div class=\"firstrevisionheader\" style=\"text-align: center\">" .
 488                         $sk->revUserTools( $this->mNewRev ) . "<br/>" . $sk->revComment( $this->mNewRev ) . $nextlink . "</div>\n";
 489
 490                 $wgOut->addHTML( $header );
 491
 492                 $wgOut->setSubtitle( wfMsgExt( 'difference', array( 'parseinline' ) ) );
 493                 $wgOut->setRobotPolicy( 'noindex,nofollow' );
 494
 495                 wfProfileOut( __METHOD__ );
 496         }
 497
 498         function htmlDiffArgument(){
 499                 global $wgEnableHtmlDiff;
 500                 if($wgEnableHtmlDiff){
 501                         if($this->htmldiff){
 502                                 return '&htmldiff=1';
 503                         }else{
 504                                 return '&htmldiff=0';
 505                         }
 506                 }else{
 507                         return '';
 508                 }
 509         }
 510
 511         /**
 512          * Get the diff text, send it to $wgOut
 513          * Returns false if the diff could not be generated, otherwise returns true
 514          */
 515         function showDiff( $otitle, $ntitle ) {
 516                 global $wgOut;
 517                 $diff = $this->getDiff( $otitle, $ntitle );
 518                 if ( $diff === false ) {
 519                         $wgOut->addWikiMsg( 'missing-article', "<nowiki>(fixme, bug)</nowiki>", '' );
 520                         return false;
 521                 } else {
 522                         $this->showDiffStyle();
 523                         $wgOut->addHTML( $diff );
 524                         return true;
 525                 }
 526         }
 527
 528         /**
 529          * Add style sheets and supporting JS for diff display.
 530          */
 531         function showDiffStyle() {
 532                 global $wgStylePath, $wgStyleVersion, $wgOut;
 533                 $wgOut->addStyle( 'common/diff.css' );
 534
 535                 // JS is needed to detect old versions of Mozilla to work around an annoyance bug.
 536                 $wgOut->addScript( "<script type=\"text/javascript\" src=\"$wgStylePath/common/diff.js?$wgStyleVersion\"></script>" );
 537         }
 538
 539         /**
 540          * Get complete diff table, including header
 541          *
 542          * @param Title $otitle Old title
 543          * @param Title $ntitle New title
 544          * @return mixed
 545          */
 546         function getDiff( $otitle, $ntitle ) {
 547                 $body = $this->getDiffBody();
 548                 if ( $body === false ) {
 549                         return false;
 550                 } else {
 551                         $multi = $this->getMultiNotice();
 552                         return $this->addHeader( $body, $otitle, $ntitle, $multi );
 553                 }
 554         }
 555
 556         /**
 557          * Get the diff table body, without header
 558          *
 559          * @return mixed
 560          */
 561         function getDiffBody() {
 562                 global $wgMemc;
 563                 wfProfileIn( __METHOD__ );
 564                 $this->mCacheHit = true;
 565                 // Check if the diff should be hidden from this user
 566                 if ( !$this->loadRevisionData() )
 567                         return '';
 568                 if ( $this->mOldRev && !$this->mOldRev->userCan(Revision::DELETED_TEXT) ) {
 569                         return '';
 570                 } else if ( $this->mNewRev && !$this->mNewRev->userCan(Revision::DELETED_TEXT) ) {
 571                         return '';
 572                 } else if ( $this->mOldRev && $this->mNewRev && $this->mOldRev->getID() == $this->mNewRev->getID() ) {
 573                         return '';
 574                 }
 575                 // Cacheable?
 576                 $key = false;
 577                 if ( $this->mOldid && $this->mNewid ) {
 578                         $key = wfMemcKey( 'diff', 'version', MW_DIFF_VERSION, 'oldid', $this->mOldid, 'newid', $this->mNewid );
 579                         // Try cache
 580                         if ( !$this->mRefreshCache ) {
 581                                 $difftext = $wgMemc->get( $key );
 582                                 if ( $difftext ) {
 583                                         wfIncrStats( 'diff_cache_hit' );
 584                                         $difftext = $this->localiseLineNumbers( $difftext );
 585                                         $difftext .= "\n<!-- diff cache key $key -->\n";
 586                                         wfProfileOut( __METHOD__ );
 587                                         return $difftext;
 588                                 }
 589                         } // don't try to load but save the result
 590                 }
 591                 $this->mCacheHit = false;
 592
 593                 // Loadtext is permission safe, this just clears out the diff
 594                 if ( !$this->loadText() ) {
 595                         wfProfileOut( __METHOD__ );
 596                         return false;
 597                 }
 598
 599                 $difftext = $this->generateDiffBody( $this->mOldtext, $this->mNewtext );
 600
 601                 // Save to cache for 7 days
 602                 if ( !wfRunHooks( 'AbortDiffCache', array( &$this ) ) ) {
 603                         wfIncrStats( 'diff_uncacheable' );
 604                 } else if ( $key !== false && $difftext !== false ) {
 605                         wfIncrStats( 'diff_cache_miss' );
 606                         $wgMemc->set( $key, $difftext, 7*86400 );
 607                 } else {
 608                         wfIncrStats( 'diff_uncacheable' );
 609                 }
 610                 // Replace line numbers with the text in the user's language
 611                 if ( $difftext !== false ) {
 612                         $difftext = $this->localiseLineNumbers( $difftext );
 613                 }
 614                 wfProfileOut( __METHOD__ );
 615                 return $difftext;
 616         }
 617
 618         /**
 619          * Generate a diff, no caching
 620          * $otext and $ntext must be already segmented
 621          */
 622         function generateDiffBody( $otext, $ntext ) {
 623                 global $wgExternalDiffEngine, $wgContLang;
 624
 625                 $otext = str_replace( "\r\n", "\n", $otext );
 626                 $ntext = str_replace( "\r\n", "\n", $ntext );
 627
 628                 if ( $wgExternalDiffEngine == 'wikidiff' ) {
 629                         # For historical reasons, external diff engine expects
 630                         # input text to be HTML-escaped already
 631                         $otext = htmlspecialchars ( $wgContLang->segmentForDiff( $otext ) );
 632                         $ntext = htmlspecialchars ( $wgContLang->segmentForDiff( $ntext ) );
 633                         if( !function_exists( 'wikidiff_do_diff' ) ) {
 634                                 dl('php_wikidiff.so');
 635                         }
 636                         return $wgContLang->unsegementForDiff( wikidiff_do_diff( $otext, $ntext, 2 ) ) .
 637                         $this->debug( 'wikidiff1' );
 638                 }
 639
 640                 if ( $wgExternalDiffEngine == 'wikidiff2' ) {
 641                         # Better external diff engine, the 2 may some day be dropped
 642                         # This one does the escaping and segmenting itself
 643                         if ( !function_exists( 'wikidiff2_do_diff' ) ) {
 644                                 wfProfileIn( __METHOD__ . "-dl" );
 645                                 @dl('php_wikidiff2.so');
 646                                 wfProfileOut( __METHOD__ . "-dl" );
 647                         }
 648                         if ( function_exists( 'wikidiff2_do_diff' ) ) {
 649                                 wfProfileIn( 'wikidiff2_do_diff' );
 650                                 $text = wikidiff2_do_diff( $otext, $ntext, 2 );
 651                                 $text .= $this->debug( 'wikidiff2' );
 652                                 wfProfileOut( 'wikidiff2_do_diff' );
 653                                 return $text;
 654                         }
 655                 }
 656                 if ( $wgExternalDiffEngine != 'wikidiff3' && $wgExternalDiffEngine !== false ) {
 657                         # Diff via the shell
 658                         global $wgTmpDirectory;
 659                         $tempName1 = tempnam( $wgTmpDirectory, 'diff_' );
 660                         $tempName2 = tempnam( $wgTmpDirectory, 'diff_' );
 661
 662                         $tempFile1 = fopen( $tempName1, "w" );
 663                         if ( !$tempFile1 ) {
 664                                 wfProfileOut( __METHOD__ );
 665                                 return false;
 666                         }
 667                         $tempFile2 = fopen( $tempName2, "w" );
 668                         if ( !$tempFile2 ) {
 669                                 wfProfileOut( __METHOD__ );
 670                                 return false;
 671                         }
 672                         fwrite( $tempFile1, $otext );
 673                         fwrite( $tempFile2, $ntext );
 674                         fclose( $tempFile1 );
 675                         fclose( $tempFile2 );
 676                         $cmd = wfEscapeShellArg( $wgExternalDiffEngine, $tempName1, $tempName2 );
 677                         wfProfileIn( __METHOD__ . "-shellexec" );
 678                         $difftext = wfShellExec( $cmd );
 679                         $difftext .= $this->debug( "external $wgExternalDiffEngine" );
 680                         wfProfileOut( __METHOD__ . "-shellexec" );
 681                         unlink( $tempName1 );
 682                         unlink( $tempName2 );
 683                         return $difftext;
 684                 }
 685
 686                 # Native PHP diff
 687                 $ota = explode( "\n", $wgContLang->segmentForDiff( $otext ) );
 688                 $nta = explode( "\n", $wgContLang->segmentForDiff( $ntext ) );
 689                 $diffs = new Diff( $ota, $nta );
 690                 $formatter = new TableDiffFormatter();
 691                 return $wgContLang->unsegmentForDiff( $formatter->format( $diffs ) ) .
 692                 $this->debug();
 693         }
 694
 695         /**
 696          * Generate a debug comment indicating diff generating time,
 697          * server node, and generator backend.
 698          */
 699         protected function debug( $generator="internal" ) {
 700                 global $wgShowHostnames;
 701                 $data = array( $generator );
 702                 if( $wgShowHostnames ) {
 703                         $data[] = wfHostname();
 704                 }
 705                 $data[] = wfTimestamp( TS_DB );
 706                 return "<!-- diff generator: " .
 707                 implode( " ",
 708                 array_map(
 709                                         "htmlspecialchars",
 710                 $data ) ) .
 711                         " -->\n";
 712         }
 713
 714         /**
 715          * Replace line numbers with the text in the user's language
 716          */
 717         function localiseLineNumbers( $text ) {
 718                 return preg_replace_callback( '/<!--LINE (\d+)-->/',
 719                 array( &$this, 'localiseLineNumbersCb' ), $text );
 720         }
 721
 722         function localiseLineNumbersCb( $matches ) {
 723                 global $wgLang;
 724                 return wfMsgExt( 'lineno', array (), $wgLang->formatNum( $matches[1] ) );
 725         }
 726
 727
 728         /**
 729          * If there are revisions between the ones being compared, return a note saying so.
 730          */
 731         function getMultiNotice() {
 732                 if ( !is_object($this->mOldRev) || !is_object($this->mNewRev) )
 733                 return '';
 734
 735                 if( !$this->mOldPage->equals( $this->mNewPage ) ) {
 736                         // Comparing two different pages? Count would be meaningless.
 737                         return '';
 738                 }
 739
 740                 $oldid = $this->mOldRev->getId();
 741                 $newid = $this->mNewRev->getId();
 742                 if ( $oldid > $newid ) {
 743                         $tmp = $oldid; $oldid = $newid; $newid = $tmp;
 744                 }
 745
 746                 $n = $this->mTitle->countRevisionsBetween( $oldid, $newid );
 747                 if ( !$n )
 748                 return '';
 749
 750                 return wfMsgExt( 'diff-multi', array( 'parseinline' ), $n );
 751         }
 752
 753
 754         /**
 755          * Add the header to a diff body
 756          */
 757         static function addHeader( $diff, $otitle, $ntitle, $multi = '' ) {
 758                 $header = "
 759                 <table class='diff'>
 760                 <col class='diff-marker' />
 761                 <col class='diff-content' />
 762                 <col class='diff-marker' />
 763                 <col class='diff-content' />
 764                 <tr valign='top'>
 765                 <td colspan='2' class='diff-otitle'>{$otitle}</td>
 766                 <td colspan='2' class='diff-ntitle'>{$ntitle}</td>
 767                 </tr>
 768                 ";
 769
 770                 if ( $multi != '' )
 771                 $header .= "<tr><td colspan='4' align='center' class='diff-multi'>{$multi}</td></tr>";
 772
 773                 return $header . $diff . "</table>";
 774         }
 775
 776         /**
 777          * Use specified text instead of loading from the database
 778          */
 779         function setText( $oldText, $newText ) {
 780                 $this->mOldtext = $oldText;
 781                 $this->mNewtext = $newText;
 782                 $this->mTextLoaded = 2;
 783                 $this->mRevisionsLoaded = true;
 784         }
 785
 786         /**
 787          * Load revision metadata for the specified articles. If newid is 0, then compare
 788          * the old article in oldid to the current article; if oldid is 0, then
 789          * compare the current article to the immediately previous one (ignoring the
 790          * value of newid).
 791          *
 792          * If oldid is false, leave the corresponding revision object set
 793          * to false. This is impossible via ordinary user input, and is provided for
 794          * API convenience.
 795          */
 796         function loadRevisionData() {
 797                 global $wgLang, $wgUser;
 798                 if ( $this->mRevisionsLoaded ) {
 799                         return true;
 800                 } else {
 801                         // Whether it succeeds or fails, we don't want to try again
 802                         $this->mRevisionsLoaded = true;
 803                 }
 804
 805                 // Load the new revision object
 806                 $this->mNewRev = $this->mNewid
 807                         ? Revision::newFromId( $this->mNewid )
 808                         : Revision::newFromTitle( $this->mTitle );
 809                 if( !$this->mNewRev instanceof Revision )
 810                         return false;
 811
 812                 // Update the new revision ID in case it was 0 (makes life easier doing UI stuff)
 813                 $this->mNewid = $this->mNewRev->getId();
 814
 815                 // Check if page is editable
 816                 $editable = $this->mNewRev->getTitle()->userCan( 'edit' );
 817
 818                 // Set assorted variables
 819                 $timestamp = $wgLang->timeanddate( $this->mNewRev->getTimestamp(), true );
 820                 $this->mNewPage = $this->mNewRev->getTitle();
 821                 if( $this->mNewRev->isCurrent() ) {
 822                         $newLink = $this->mNewPage->escapeLocalUrl( 'oldid=' . $this->mNewid );
 823                         $this->mPagetitle = wfMsgHTML( 'currentrev-asof', $timestamp );
 824                         $newEdit = $this->mNewPage->escapeLocalUrl( 'action=edit' );
 825
 826                         $this->mNewtitle = "<a href='$newLink'>{$this->mPagetitle}</a>";
 827                         $this->mNewtitle .= " (<a href='$newEdit'>" . wfMsgHtml( $editable ? 'editold' : 'viewsourceold' ) . "</a>)";
 828
 829                 } else {
 830                         $newLink = $this->mNewPage->escapeLocalUrl( 'oldid=' . $this->mNewid );
 831                         $newEdit = $this->mNewPage->escapeLocalUrl( 'action=edit&oldid=' . $this->mNewid );
 832                         $this->mPagetitle = wfMsgHTML( 'revisionasof', $timestamp );
 833
 834                         $this->mNewtitle = "<a href='$newLink'>{$this->mPagetitle}</a>";
 835                         $this->mNewtitle .= " (<a href='$newEdit'>" . wfMsgHtml( $editable ? 'editold' : 'viewsourceold' ) . "</a>)";
 836                 }
 837                 if ( !$this->mNewRev->userCan(Revision::DELETED_TEXT) ) {
 838                         $this->mNewtitle = "<span class='history-deleted'>{$this->mPagetitle}</span>";
 839                 } else if ( $this->mNewRev->isDeleted(Revision::DELETED_TEXT) ) {
 840                         $this->mNewtitle = '<span class="history-deleted">'.$this->mNewtitle.'</span>';
 841                 }
 842
 843                 // Load the old revision object
 844                 $this->mOldRev = false;
 845                 if( $this->mOldid ) {
 846                         $this->mOldRev = Revision::newFromId( $this->mOldid );
 847                 } elseif ( $this->mOldid === 0 ) {
 848                         $rev = $this->mNewRev->getPrevious();
 849                         if( $rev ) {
 850                                 $this->mOldid = $rev->getId();
 851                                 $this->mOldRev = $rev;
 852                         } else {
 853                                 // No previous revision; mark to show as first-version only.
 854                                 $this->mOldid = false;
 855                                 $this->mOldRev = false;
 856                         }
 857                 }/* elseif ( $this->mOldid === false ) leave mOldRev false; */
 858
 859                 if( is_null( $this->mOldRev ) ) {
 860                         return false;
 861                 }
 862
 863                 if ( $this->mOldRev ) {
 864                         $this->mOldPage = $this->mOldRev->getTitle();
 865
 866                         $t = $wgLang->timeanddate( $this->mOldRev->getTimestamp(), true );
 867                         $oldLink = $this->mOldPage->escapeLocalUrl( 'oldid=' . $this->mOldid );
 868                         $oldEdit = $this->mOldPage->escapeLocalUrl( 'action=edit&oldid=' . $this->mOldid );
 869                         $this->mOldPagetitle = htmlspecialchars( wfMsg( 'revisionasof', $t ) );
 870
 871                         $this->mOldtitle = "<a href='$oldLink'>{$this->mOldPagetitle}</a>"
 872                         . " (<a href='$oldEdit'>" . wfMsgHtml( $editable ? 'editold' : 'viewsourceold' ) . "</a>)";
 873                         // Add an "undo" link
 874                         $newUndo = $this->mNewPage->escapeLocalUrl( 'action=edit&undoafter=' . $this->mOldid . '&undo=' . $this->mNewid);
 875                         $htmlLink = htmlspecialchars( wfMsg( 'editundo' ) );
 876                         $htmlTitle = $wgUser->getSkin()->tooltip( 'undo' );
 877                         if( $editable && !$this->mOldRev->isDeleted( Revision::DELETED_TEXT ) && !$this->mNewRev->isDeleted( Revision::DELETED_TEXT ) ) {
 878                                 $this->mNewtitle .= " (<a href='$newUndo' $htmlTitle>" . $htmlLink . "</a>)";
 879                         }
 880
 881                         if( !$this->mOldRev->userCan( Revision::DELETED_TEXT ) ) {
 882                                 $this->mOldtitle = '<span class="history-deleted">' . $this->mOldPagetitle . '</span>';
 883                         } else if( $this->mOldRev->isDeleted( Revision::DELETED_TEXT ) ) {
 884                                 $this->mOldtitle = '<span class="history-deleted">' . $this->mOldtitle . '</span>';
 885                         }
 886                 }
 887
 888                 return true;
 889         }
 890
 891         /**
 892          * Load the text of the revisions, as well as revision data.
 893          */
 894         function loadText() {
 895                 if ( $this->mTextLoaded == 2 ) {
 896                         return true;
 897                 } else {
 898                         // Whether it succeeds or fails, we don't want to try again
 899                         $this->mTextLoaded = 2;
 900                 }
 901
 902                 if ( !$this->loadRevisionData() ) {
 903                         return false;
 904                 }
 905                 if ( $this->mOldRev ) {
 906                         $this->mOldtext = $this->mOldRev->getText( Revision::FOR_THIS_USER );
 907                         if ( $this->mOldtext === false ) {
 908                                 return false;
 909                         }
 910                 }
 911                 if ( $this->mNewRev ) {
 912                         $this->mNewtext = $this->mNewRev->getText( Revision::FOR_THIS_USER );
 913                         if ( $this->mNewtext === false ) {
 914                                 return false;
 915                         }
 916                 }
 917                 return true;
 918         }
 919
 920         /**
 921          * Load the text of the new revision, not the old one
 922          */
 923         function loadNewText() {
 924                 if ( $this->mTextLoaded >= 1 ) {
 925                         return true;
 926                 } else {
 927                         $this->mTextLoaded = 1;
 928                 }
 929                 if ( !$this->loadRevisionData() ) {
 930                         return false;
 931                 }
 932                 $this->mNewtext = $this->mNewRev->getText( Revision::FOR_THIS_USER );
 933                 return true;
 934         }
 935
 936
 937 }
 938
 939 // A PHP diff engine for phpwiki. (Taken from phpwiki-1.3.3)
 940 //
 941 // Copyright (C) 2000, 2001 Geoffrey T. Dairiki <dairiki@dairiki.org>
 942 // You may copy this code freely under the conditions of the GPL.
 943 //
 944
 945 define('USE_ASSERTS', function_exists('assert'));
 946
 947 /**
 948  * @todo document
 949  * @private
 950  * @ingroup DifferenceEngine
 951  */
 952 class _DiffOp {
 953         var $type;
 954         var $orig;
 955         var $closing;
 956
 957         function reverse() {
 958                 trigger_error('pure virtual', E_USER_ERROR);
 959         }
 960
 961         function norig() {
 962                 return $this->orig ? sizeof($this->orig) : 0;
 963         }
 964
 965         function nclosing() {
 966                 return $this->closing ? sizeof($this->closing) : 0;
 967         }
 968 }
 969
 970 /**
 971  * @todo document
 972  * @private
 973  * @ingroup DifferenceEngine
 974  */
 975 class _DiffOp_Copy extends _DiffOp {
 976         var $type = 'copy';
 977
 978         function _DiffOp_Copy ($orig, $closing = false) {
 979                 if (!is_array($closing))
 980                 $closing = $orig;
 981                 $this->orig = $orig;
 982                 $this->closing = $closing;
 983         }
 984
 985         function reverse() {
 986                 return new _DiffOp_Copy($this->closing, $this->orig);
 987         }
 988 }
 989
 990 /**
 991  * @todo document
 992  * @private
 993  * @ingroup DifferenceEngine
 994  */
 995 class _DiffOp_Delete extends _DiffOp {
 996         var $type = 'delete';
 997
 998         function _DiffOp_Delete ($lines) {
 999                 $this->orig = $lines;
1000                 $this->closing = false;
1001         }
1002
1003         function reverse() {
1004                 return new _DiffOp_Add($this->orig);
1005         }
1006 }
1007
1008 /**
1009  * @todo document
1010  * @private
1011  * @ingroup DifferenceEngine
1012  */
1013 class _DiffOp_Add extends _DiffOp {
1014         var $type = 'add';
1015
1016         function _DiffOp_Add ($lines) {
1017                 $this->closing = $lines;
1018                 $this->orig = false;
1019         }
1020
1021         function reverse() {
1022                 return new _DiffOp_Delete($this->closing);
1023         }
1024 }
1025
1026 /**
1027  * @todo document
1028  * @private
1029  * @ingroup DifferenceEngine
1030  */
1031 class _DiffOp_Change extends _DiffOp {
1032         var $type = 'change';
1033
1034         function _DiffOp_Change ($orig, $closing) {
1035                 $this->orig = $orig;
1036                 $this->closing = $closing;
1037         }
1038
1039         function reverse() {
1040                 return new _DiffOp_Change($this->closing, $this->orig);
1041         }
1042 }
1043
1044 /**
1045  * Class used internally by Diff to actually compute the diffs.
1046  *
1047  * The algorithm used here is mostly lifted from the perl module
1048  * Algorithm::Diff (version 1.06) by Ned Konz, which is available at:
1049  *       http://www.perl.com/CPAN/authors/id/N/NE/NEDKONZ/Algorithm-Diff-1.06.zip
1050  *
1051  * More ideas are taken from:
1052  *       http://www.ics.uci.edu/~eppstein/161/960229.html
1053  *
1054  * Some ideas are (and a bit of code) are from from analyze.c, from GNU
1055  * diffutils-2.7, which can be found at:
1056  *       ftp://gnudist.gnu.org/pub/gnu/diffutils/diffutils-2.7.tar.gz
1057  *
1058  * closingly, some ideas (subdivision by NCHUNKS > 2, and some optimizations)
1059  * are my own.
1060  *
1061  * Line length limits for robustness added by Tim Starling, 2005-08-31
1062  * Alternative implementation added by Guy Van den Broeck, 2008-07-30
1063  *
1064  * @author Geoffrey T. Dairiki, Tim Starling, Guy Van den Broeck
1065  * @private
1066  * @ingroup DifferenceEngine
1067  */
1068 class _DiffEngine {
1069
1070         const MAX_XREF_LENGTH =  10000;
1071
1072         function diff ($from_lines, $to_lines){
1073                 wfProfileIn( __METHOD__ );
1074
1075                 // Diff and store locally
1076                 $this->diff_local($from_lines, $to_lines);
1077
1078                 // Merge edits when possible
1079                 $this->_shift_boundaries($from_lines, $this->xchanged, $this->ychanged);
1080                 $this->_shift_boundaries($to_lines, $this->ychanged, $this->xchanged);
1081
1082                 // Compute the edit operations.
1083                 $n_from = sizeof($from_lines);
1084                 $n_to = sizeof($to_lines);
1085
1086                 $edits = array();
1087                 $xi = $yi = 0;
1088                 while ($xi < $n_from || $yi < $n_to) {
1089                         USE_ASSERTS && assert($yi < $n_to || $this->xchanged[$xi]);
1090                         USE_ASSERTS && assert($xi < $n_from || $this->ychanged[$yi]);
1091
1092                         // Skip matching "snake".
1093                         $copy = array();
1094                         while ( $xi < $n_from && $yi < $n_to
1095                         && !$this->xchanged[$xi] && !$this->ychanged[$yi]) {
1096                                 $copy[] = $from_lines[$xi++];
1097                                 ++$yi;
1098                         }
1099                         if ($copy)
1100                         $edits[] = new _DiffOp_Copy($copy);
1101
1102                         // Find deletes & adds.
1103                         $delete = array();
1104                         while ($xi < $n_from && $this->xchanged[$xi])
1105                         $delete[] = $from_lines[$xi++];
1106
1107                         $add = array();
1108                         while ($yi < $n_to && $this->ychanged[$yi])
1109                         $add[] = $to_lines[$yi++];
1110
1111                         if ($delete && $add)
1112                         $edits[] = new _DiffOp_Change($delete, $add);
1113                         elseif ($delete)
1114                         $edits[] = new _DiffOp_Delete($delete);
1115                         elseif ($add)
1116                         $edits[] = new _DiffOp_Add($add);
1117                 }
1118                 wfProfileOut( __METHOD__ );
1119                 return $edits;
1120         }
1121
1122         function diff_local ($from_lines, $to_lines) {
1123                 global $wgExternalDiffEngine;
1124                 wfProfileIn( __METHOD__);
1125
1126                 if($wgExternalDiffEngine == 'wikidiff3'){
1127                         // wikidiff3
1128                         $wikidiff3 = new WikiDiff3();
1129                         $wikidiff3->diff($from_lines, $to_lines);
1130                         $this->xchanged = $wikidiff3->removed;
1131                         $this->ychanged = $wikidiff3->added;
1132                         unset($wikidiff3);
1133                 }else{
1134                         // old diff
1135                         $n_from = sizeof($from_lines);
1136                         $n_to = sizeof($to_lines);
1137                         $this->xchanged = $this->ychanged = array();
1138                         $this->xv = $this->yv = array();
1139                         $this->xind = $this->yind = array();
1140                         unset($this->seq);
1141                         unset($this->in_seq);
1142                         unset($this->lcs);
1143
1144                         // Skip leading common lines.
1145                         for ($skip = 0; $skip < $n_from && $skip < $n_to; $skip++) {
1146                                 if ($from_lines[$skip] !== $to_lines[$skip])
1147                                 break;
1148                                 $this->xchanged[$skip] = $this->ychanged[$skip] = false;
1149                         }
1150                         // Skip trailing common lines.
1151                         $xi = $n_from; $yi = $n_to;
1152                         for ($endskip = 0; --$xi > $skip && --$yi > $skip; $endskip++) {
1153                                 if ($from_lines[$xi] !== $to_lines[$yi])
1154                                 break;
1155                                 $this->xchanged[$xi] = $this->ychanged[$yi] = false;
1156                         }
1157
1158                         // Ignore lines which do not exist in both files.
1159                         for ($xi = $skip; $xi < $n_from - $endskip; $xi++) {
1160                                 $xhash[$this->_line_hash($from_lines[$xi])] = 1;
1161                         }
1162
1163                         for ($yi = $skip; $yi < $n_to - $endskip; $yi++) {
1164                                 $line = $to_lines[$yi];
1165                                 if ( ($this->ychanged[$yi] = empty($xhash[$this->_line_hash($line)])) )
1166                                 continue;
1167                                 $yhash[$this->_line_hash($line)] = 1;
1168                                 $this->yv[] = $line;
1169                                 $this->yind[] = $yi;
1170                         }
1171                         for ($xi = $skip; $xi < $n_from - $endskip; $xi++) {
1172                                 $line = $from_lines[$xi];
1173                                 if ( ($this->xchanged[$xi] = empty($yhash[$this->_line_hash($line)])) )
1174                                 continue;
1175                                 $this->xv[] = $line;
1176                                 $this->xind[] = $xi;
1177                         }
1178
1179                         // Find the LCS.
1180                         $this->_compareseq(0, sizeof($this->xv), 0, sizeof($this->yv));
1181                 }
1182                 wfProfileOut( __METHOD__ );
1183         }
1184
1185         /**
1186          * Returns the whole line if it's small enough, or the MD5 hash otherwise
1187          */
1188         function _line_hash( $line ) {
1189                 if ( strlen( $line ) > self::MAX_XREF_LENGTH ) {
1190                         return md5( $line );
1191                 } else {
1192                         return $line;
1193                 }
1194         }
1195
1196         /* Divide the Largest Common Subsequence (LCS) of the sequences
1197          * [XOFF, XLIM) and [YOFF, YLIM) into NCHUNKS approximately equally
1198          * sized segments.
1199          *
1200          * Returns (LCS, PTS).  LCS is the length of the LCS. PTS is an
1201          * array of NCHUNKS+1 (X, Y) indexes giving the diving points between
1202          * sub sequences.  The first sub-sequence is contained in [X0, X1),
1203          * [Y0, Y1), the second in [X1, X2), [Y1, Y2) and so on.  Note
1204          * that (X0, Y0) == (XOFF, YOFF) and
1205          * (X[NCHUNKS], Y[NCHUNKS]) == (XLIM, YLIM).
1206          *
1207          * This function assumes that the first lines of the specified portions
1208          * of the two files do not match, and likewise that the last lines do not
1209          * match.  The caller must trim matching lines from the beginning and end
1210          * of the portions it is going to specify.
1211          */
1212         function _diag ($xoff, $xlim, $yoff, $ylim, $nchunks) {
1213                 $flip = false;
1214
1215                 if ($xlim - $xoff > $ylim - $yoff) {
1216                         // Things seems faster (I'm not sure I understand why)
1217                         // when the shortest sequence in X.
1218                         $flip = true;
1219                         list ($xoff, $xlim, $yoff, $ylim)
1220                         = array( $yoff, $ylim, $xoff, $xlim);
1221                 }
1222
1223                 if ($flip)
1224                 for ($i = $ylim - 1; $i >= $yoff; $i--)
1225                 $ymatches[$this->xv[$i]][] = $i;
1226                 else
1227                 for ($i = $ylim - 1; $i >= $yoff; $i--)
1228                 $ymatches[$this->yv[$i]][] = $i;
1229
1230                 $this->lcs = 0;
1231                 $this->seq[0]= $yoff - 1;
1232                 $this->in_seq = array();
1233                 $ymids[0] = array();
1234
1235                 $numer = $xlim - $xoff + $nchunks - 1;
1236                 $x = $xoff;
1237                 for ($chunk = 0; $chunk < $nchunks; $chunk++) {
1238                         if ($chunk > 0)
1239                         for ($i = 0; $i <= $this->lcs; $i++)
1240                         $ymids[$i][$chunk-1] = $this->seq[$i];
1241
1242                         $x1 = $xoff + (int)(($numer + ($xlim-$xoff)*$chunk) / $nchunks);
1243                         for ( ; $x < $x1; $x++) {
1244                                 $line = $flip ? $this->yv[$x] : $this->xv[$x];
1245                                 if (empty($ymatches[$line]))
1246                                 continue;
1247                                 $matches = $ymatches[$line];
1248                                 reset($matches);
1249                                 while (list ($junk, $y) = each($matches))
1250                                 if (empty($this->in_seq[$y])) {
1251                                         $k = $this->_lcs_pos($y);
1252                                         USE_ASSERTS && assert($k > 0);
1253                                         $ymids[$k] = $ymids[$k-1];
1254                                         break;
1255                                 }
1256                                 while (list ( /* $junk */, $y) = each($matches)) {
1257                                         if ($y > $this->seq[$k-1]) {
1258                                                 USE_ASSERTS && assert($y < $this->seq[$k]);
1259                                                 // Optimization: this is a common case:
1260                                                 //      next match is just replacing previous match.
1261                                                 $this->in_seq[$this->seq[$k]] = false;
1262                                                 $this->seq[$k] = $y;
1263                                                 $this->in_seq[$y] = 1;
1264                                         } else if (empty($this->in_seq[$y])) {
1265                                                 $k = $this->_lcs_pos($y);
1266                                                 USE_ASSERTS && assert($k > 0);
1267                                                 $ymids[$k] = $ymids[$k-1];
1268                                         }
1269                                 }
1270                         }
1271                 }
1272
1273                 $seps[] = $flip ? array($yoff, $xoff) : array($xoff, $yoff);
1274                 $ymid = $ymids[$this->lcs];
1275                 for ($n = 0; $n < $nchunks - 1; $n++) {
1276                         $x1 = $xoff + (int)(($numer + ($xlim - $xoff) * $n) / $nchunks);
1277                         $y1 = $ymid[$n] + 1;
1278                         $seps[] = $flip ? array($y1, $x1) : array($x1, $y1);
1279                 }
1280                 $seps[] = $flip ? array($ylim, $xlim) : array($xlim, $ylim);
1281
1282                 return array($this->lcs, $seps);
1283         }
1284
1285         function _lcs_pos ($ypos) {
1286                 $end = $this->lcs;
1287                 if ($end == 0 || $ypos > $this->seq[$end]) {
1288                         $this->seq[++$this->lcs] = $ypos;
1289                         $this->in_seq[$ypos] = 1;
1290                         return $this->lcs;
1291                 }
1292
1293                 $beg = 1;
1294                 while ($beg < $end) {
1295                         $mid = (int)(($beg + $end) / 2);
1296                         if ( $ypos > $this->seq[$mid] )
1297                         $beg = $mid + 1;
1298                         else
1299                         $end = $mid;
1300                 }
1301
1302                 USE_ASSERTS && assert($ypos != $this->seq[$end]);
1303
1304                 $this->in_seq[$this->seq[$end]] = false;
1305                 $this->seq[$end] = $ypos;
1306                 $this->in_seq[$ypos] = 1;
1307                 return $end;
1308         }
1309
1310         /* Find LCS of two sequences.
1311          *
1312          * The results are recorded in the vectors $this->{x,y}changed[], by
1313          * storing a 1 in the element for each line that is an insertion
1314          * or deletion (ie. is not in the LCS).
1315          *
1316          * The subsequence of file 0 is [XOFF, XLIM) and likewise for file 1.
1317          *
1318          * Note that XLIM, YLIM are exclusive bounds.
1319          * All line numbers are origin-0 and discarded lines are not counted.
1320          */
1321         function _compareseq ($xoff, $xlim, $yoff, $ylim) {
1322                 // Slide down the bottom initial diagonal.
1323                 while ($xoff < $xlim && $yoff < $ylim
1324                 && $this->xv[$xoff] == $this->yv[$yoff]) {
1325                         ++$xoff;
1326                         ++$yoff;
1327                 }
1328
1329                 // Slide up the top initial diagonal.
1330                 while ($xlim > $xoff && $ylim > $yoff
1331                 && $this->xv[$xlim - 1] == $this->yv[$ylim - 1]) {
1332                         --$xlim;
1333                         --$ylim;
1334                 }
1335
1336                 if ($xoff == $xlim || $yoff == $ylim)
1337                 $lcs = 0;
1338                 else {
1339                         // This is ad hoc but seems to work well.
1340                         //$nchunks = sqrt(min($xlim - $xoff, $ylim - $yoff) / 2.5);
1341                         //$nchunks = max(2,min(8,(int)$nchunks));
1342                         $nchunks = min(7, $xlim - $xoff, $ylim - $yoff) + 1;
1343                         list ($lcs, $seps)
1344                         = $this->_diag($xoff,$xlim,$yoff, $ylim,$nchunks);
1345                 }
1346
1347                 if ($lcs == 0) {
1348                         // X and Y sequences have no common subsequence:
1349                         // mark all changed.
1350                         while ($yoff < $ylim)
1351                         $this->ychanged[$this->yind[$yoff++]] = 1;
1352                         while ($xoff < $xlim)
1353                         $this->xchanged[$this->xind[$xoff++]] = 1;
1354                 } else {
1355                         // Use the partitions to split this problem into subproblems.
1356                         reset($seps);
1357                         $pt1 = $seps[0];
1358                         while ($pt2 = next($seps)) {
1359                                 $this->_compareseq ($pt1[0], $pt2[0], $pt1[1], $pt2[1]);
1360                                 $pt1 = $pt2;
1361                         }
1362                 }
1363         }
1364
1365         /* Adjust inserts/deletes of identical lines to join changes
1366          * as much as possible.
1367          *
1368          * We do something when a run of changed lines include a
1369          * line at one end and has an excluded, identical line at the other.
1370          * We are free to choose which identical line is included.
1371          * `compareseq' usually chooses the one at the beginning,
1372          * but usually it is cleaner to consider the following identical line
1373          * to be the "change".
1374          *
1375          * This is extracted verbatim from analyze.c (GNU diffutils-2.7).
1376          */
1377         function _shift_boundaries ($lines, &$changed, $other_changed) {
1378                 wfProfileIn( __METHOD__ );
1379                 $i = 0;
1380                 $j = 0;
1381
1382                 USE_ASSERTS && assert('sizeof($lines) == sizeof($changed)');
1383                 $len = sizeof($lines);
1384                 $other_len = sizeof($other_changed);
1385
1386                 while (1) {
1387                         /*
1388                          * Scan forwards to find beginning of another run of changes.
1389                          * Also keep track of the corresponding point in the other file.
1390                          *
1391                          * Throughout this code, $i and $j are adjusted together so that
1392                          * the first $i elements of $changed and the first $j elements
1393                          * of $other_changed both contain the same number of zeros
1394                          * (unchanged lines).
1395                          * Furthermore, $j is always kept so that $j == $other_len or
1396                          * $other_changed[$j] == false.
1397                          */
1398                         while ($j < $other_len && $other_changed[$j])
1399                         $j++;
1400
1401                         while ($i < $len && ! $changed[$i]) {
1402                                 USE_ASSERTS && assert('$j < $other_len && ! $other_changed[$j]');
1403                                 $i++; $j++;
1404                                 while ($j < $other_len && $other_changed[$j])
1405                                 $j++;
1406                         }
1407
1408                         if ($i == $len)
1409                         break;
1410
1411                         $start = $i;
1412
1413                         // Find the end of this run of changes.
1414                         while (++$i < $len && $changed[$i])
1415                         continue;
1416
1417                         do {
1418                                 /*
1419                                  * Record the length of this run of changes, so that
1420                                  * we can later determine whether the run has grown.
1421                                  */
1422                                 $runlength = $i - $start;
1423
1424                                 /*
1425                                  * Move the changed region back, so long as the
1426                                  * previous unchanged line matches the last changed one.
1427                                  * This merges with previous changed regions.
1428                                  */
1429                                 while ($start > 0 && $lines[$start - 1] == $lines[$i - 1]) {
1430                                         $changed[--$start] = 1;
1431                                         $changed[--$i] = false;
1432                                         while ($start > 0 && $changed[$start - 1])
1433                                         $start--;
1434                                         USE_ASSERTS && assert('$j > 0');
1435                                         while ($other_changed[--$j])
1436                                         continue;
1437                                         USE_ASSERTS && assert('$j >= 0 && !$other_changed[$j]');
1438                                 }
1439
1440                                 /*
1441                                  * Set CORRESPONDING to the end of the changed run, at the last
1442                                  * point where it corresponds to a changed run in the other file.
1443                                  * CORRESPONDING == LEN means no such point has been found.
1444                                  */
1445                                 $corresponding = $j < $other_len ? $i : $len;
1446
1447                                 /*
1448                                  * Move the changed region forward, so long as the
1449                                  * first changed line matches the following unchanged one.
1450                                  * This merges with following changed regions.
1451                                  * Do this second, so that if there are no merges,
1452                                  * the changed region is moved forward as far as possible.
1453                                  */
1454                                 while ($i < $len && $lines[$start] == $lines[$i]) {
1455                                         $changed[$start++] = false;
1456                                         $changed[$i++] = 1;
1457                                         while ($i < $len && $changed[$i])
1458                                         $i++;
1459
1460                                         USE_ASSERTS && assert('$j < $other_len && ! $other_changed[$j]');
1461                                         $j++;
1462                                         if ($j < $other_len && $other_changed[$j]) {
1463                                                 $corresponding = $i;
1464                                                 while ($j < $other_len && $other_changed[$j])
1465                                                 $j++;
1466                                         }
1467                                 }
1468                         } while ($runlength != $i - $start);
1469
1470                         /*
1471                          * If possible, move the fully-merged run of changes
1472                          * back to a corresponding run in the other file.
1473                          */
1474                         while ($corresponding < $i) {
1475                                 $changed[--$start] = 1;
1476                                 $changed[--$i] = 0;
1477                                 USE_ASSERTS && assert('$j > 0');
1478                                 while ($other_changed[--$j])
1479                                 continue;
1480                                 USE_ASSERTS && assert('$j >= 0 && !$other_changed[$j]');
1481                         }
1482                 }
1483                 wfProfileOut( __METHOD__ );
1484         }
1485 }
1486
1487 /**
1488  * Class representing a 'diff' between two sequences of strings.
1489  * @todo document
1490  * @private
1491  * @ingroup DifferenceEngine
1492  */
1493 class Diff
1494 {
1495         var $edits;
1496
1497         /**
1498          * Constructor.
1499          * Computes diff between sequences of strings.
1500          *
1501          * @param $from_lines array An array of strings.
1502          *                (Typically these are lines from a file.)
1503          * @param $to_lines array An array of strings.
1504          */
1505         function Diff($from_lines, $to_lines) {
1506                 $eng = new _DiffEngine;
1507                 $this->edits = $eng->diff($from_lines, $to_lines);
1508                 //$this->_check($from_lines, $to_lines);
1509         }
1510
1511         /**
1512          * Compute reversed Diff.
1513          *
1514          * SYNOPSIS:
1515          *
1516          *      $diff = new Diff($lines1, $lines2);
1517          *      $rev = $diff->reverse();
1518          * @return object A Diff object representing the inverse of the
1519          *                                original diff.
1520          */
1521         function reverse () {
1522                 $rev = $this;
1523                 $rev->edits = array();
1524                 foreach ($this->edits as $edit) {
1525                         $rev->edits[] = $edit->reverse();
1526                 }
1527                 return $rev;
1528         }
1529
1530         /**
1531          * Check for empty diff.
1532          *
1533          * @return bool True iff two sequences were identical.
1534          */
1535         function isEmpty () {
1536                 foreach ($this->edits as $edit) {
1537                         if ($edit->type != 'copy')
1538                         return false;
1539                 }
1540                 return true;
1541         }
1542
1543         /**
1544          * Compute the length of the Longest Common Subsequence (LCS).
1545          *
1546          * This is mostly for diagnostic purposed.
1547          *
1548          * @return int The length of the LCS.
1549          */
1550         function lcs () {
1551                 $lcs = 0;
1552                 foreach ($this->edits as $edit) {
1553                         if ($edit->type == 'copy')
1554                         $lcs += sizeof($edit->orig);
1555                 }
1556                 return $lcs;
1557         }
1558
1559         /**
1560          * Get the original set of lines.
1561          *
1562          * This reconstructs the $from_lines parameter passed to the
1563          * constructor.
1564          *
1565          * @return array The original sequence of strings.
1566          */
1567         function orig() {
1568                 $lines = array();
1569
1570                 foreach ($this->edits as $edit) {
1571                         if ($edit->orig)
1572                         array_splice($lines, sizeof($lines), 0, $edit->orig);
1573                 }
1574                 return $lines;
1575         }
1576
1577         /**
1578          * Get the closing set of lines.
1579          *
1580          * This reconstructs the $to_lines parameter passed to the
1581          * constructor.
1582          *
1583          * @return array The sequence of strings.
1584          */
1585         function closing() {
1586                 $lines = array();
1587
1588                 foreach ($this->edits as $edit) {
1589                         if ($edit->closing)
1590                         array_splice($lines, sizeof($lines), 0, $edit->closing);
1591                 }
1592                 return $lines;
1593         }
1594
1595         /**
1596          * Check a Diff for validity.
1597          *
1598          * This is here only for debugging purposes.
1599          */
1600         function _check ($from_lines, $to_lines) {
1601                 wfProfileIn( __METHOD__ );
1602                 if (serialize($from_lines) != serialize($this->orig()))
1603                 trigger_error("Reconstructed original doesn't match", E_USER_ERROR);
1604                 if (serialize($to_lines) != serialize($this->closing()))
1605                 trigger_error("Reconstructed closing doesn't match", E_USER_ERROR);
1606
1607                 $rev = $this->reverse();
1608                 if (serialize($to_lines) != serialize($rev->orig()))
1609                 trigger_error("Reversed original doesn't match", E_USER_ERROR);
1610                 if (serialize($from_lines) != serialize($rev->closing()))
1611                 trigger_error("Reversed closing doesn't match", E_USER_ERROR);
1612
1613
1614                 $prevtype = 'none';
1615                 foreach ($this->edits as $edit) {
1616                         if ( $prevtype == $edit->type )
1617                         trigger_error("Edit sequence is non-optimal", E_USER_ERROR);
1618                         $prevtype = $edit->type;
1619                 }
1620
1621                 $lcs = $this->lcs();
1622                 trigger_error('Diff okay: LCS = '.$lcs, E_USER_NOTICE);
1623                 wfProfileOut( __METHOD__ );
1624         }
1625 }
1626
1627 /**
1628  * @todo document, bad name.
1629  * @private
1630  * @ingroup DifferenceEngine
1631  */
1632 class MappedDiff extends Diff
1633 {
1634         /**
1635          * Constructor.
1636          *
1637          * Computes diff between sequences of strings.
1638          *
1639          * This can be used to compute things like
1640          * case-insensitve diffs, or diffs which ignore
1641          * changes in white-space.
1642          *
1643          * @param $from_lines array An array of strings.
1644          *      (Typically these are lines from a file.)
1645          *
1646          * @param $to_lines array An array of strings.
1647          *
1648          * @param $mapped_from_lines array This array should
1649          *      have the same size number of elements as $from_lines.
1650          *      The elements in $mapped_from_lines and
1651          *      $mapped_to_lines are what is actually compared
1652          *      when computing the diff.
1653          *
1654          * @param $mapped_to_lines array This array should
1655          *      have the same number of elements as $to_lines.
1656          */
1657         function MappedDiff($from_lines, $to_lines,
1658         $mapped_from_lines, $mapped_to_lines) {
1659                 wfProfileIn( __METHOD__ );
1660
1661                 assert(sizeof($from_lines) == sizeof($mapped_from_lines));
1662                 assert(sizeof($to_lines) == sizeof($mapped_to_lines));
1663
1664                 $this->Diff($mapped_from_lines, $mapped_to_lines);
1665
1666                 $xi = $yi = 0;
1667                 for ($i = 0; $i < sizeof($this->edits); $i++) {
1668                         $orig = &$this->edits[$i]->orig;
1669                         if (is_array($orig)) {
1670                                 $orig = array_slice($from_lines, $xi, sizeof($orig));
1671                                 $xi += sizeof($orig);
1672                         }
1673
1674                         $closing = &$this->edits[$i]->closing;
1675                         if (is_array($closing)) {
1676                                 $closing = array_slice($to_lines, $yi, sizeof($closing));
1677                                 $yi += sizeof($closing);
1678                         }
1679                 }
1680                 wfProfileOut( __METHOD__ );
1681         }
1682 }
1683
1684 /**
1685  * A class to format Diffs
1686  *
1687  * This class formats the diff in classic diff format.
1688  * It is intended that this class be customized via inheritance,
1689  * to obtain fancier outputs.
1690  * @todo document
1691  * @private
1692  * @ingroup DifferenceEngine
1693  */
1694 class DiffFormatter {
1695         /**
1696          * Number of leading context "lines" to preserve.
1697          *
1698          * This should be left at zero for this class, but subclasses
1699          * may want to set this to other values.
1700          */
1701         var $leading_context_lines = 0;
1702
1703         /**
1704          * Number of trailing context "lines" to preserve.
1705          *
1706          * This should be left at zero for this class, but subclasses
1707          * may want to set this to other values.
1708          */
1709         var $trailing_context_lines = 0;
1710
1711         /**
1712          * Format a diff.
1713          *
1714          * @param $diff object A Diff object.
1715          * @return string The formatted output.
1716          */
1717         function format($diff) {
1718                 wfProfileIn( __METHOD__ );
1719
1720                 $xi = $yi = 1;
1721                 $block = false;
1722                 $context = array();
1723
1724                 $nlead = $this->leading_context_lines;
1725                 $ntrail = $this->trailing_context_lines;
1726
1727                 $this->_start_diff();
1728
1729                 foreach ($diff->edits as $edit) {
1730                         if ($edit->type == 'copy') {
1731                                 if (is_array($block)) {
1732                                         if (sizeof($edit->orig) <= $nlead + $ntrail) {
1733                                                 $block[] = $edit;
1734                                         }
1735                                         else{
1736                                                 if ($ntrail) {
1737                                                         $context = array_slice($edit->orig, 0, $ntrail);
1738                                                         $block[] = new _DiffOp_Copy($context);
1739                                                 }
1740                                                 $this->_block($x0, $ntrail + $xi - $x0,
1741                                                 $y0, $ntrail + $yi - $y0,
1742                                                 $block);
1743                                                 $block = false;
1744                                         }
1745                                 }
1746                                 $context = $edit->orig;
1747                         }
1748                         else {
1749                                 if (! is_array($block)) {
1750                                         $context = array_slice($context, sizeof($context) - $nlead);
1751                                         $x0 = $xi - sizeof($context);
1752                                         $y0 = $yi - sizeof($context);
1753                                         $block = array();
1754                                         if ($context)
1755                                         $block[] = new _DiffOp_Copy($context);
1756                                 }
1757                                 $block[] = $edit;
1758                         }
1759
1760                         if ($edit->orig)
1761                         $xi += sizeof($edit->orig);
1762                         if ($edit->closing)
1763                         $yi += sizeof($edit->closing);
1764                 }
1765
1766                 if (is_array($block))
1767                 $this->_block($x0, $xi - $x0,
1768                 $y0, $yi - $y0,
1769                 $block);
1770
1771                 $end = $this->_end_diff();
1772                 wfProfileOut( __METHOD__ );
1773                 return $end;
1774         }
1775
1776         function _block($xbeg, $xlen, $ybeg, $ylen, &$edits) {
1777                 wfProfileIn( __METHOD__ );
1778                 $this->_start_block($this->_block_header($xbeg, $xlen, $ybeg, $ylen));
1779                 foreach ($edits as $edit) {
1780                         if ($edit->type == 'copy')
1781                         $this->_context($edit->orig);
1782                         elseif ($edit->type == 'add')
1783                         $this->_added($edit->closing);
1784                         elseif ($edit->type == 'delete')
1785                         $this->_deleted($edit->orig);
1786                         elseif ($edit->type == 'change')
1787                         $this->_changed($edit->orig, $edit->closing);
1788                         else
1789                         trigger_error('Unknown edit type', E_USER_ERROR);
1790                 }
1791                 $this->_end_block();
1792                 wfProfileOut( __METHOD__ );
1793         }
1794
1795         function _start_diff() {
1796                 ob_start();
1797         }
1798
1799         function _end_diff() {
1800                 $val = ob_get_contents();
1801                 ob_end_clean();
1802                 return $val;
1803         }
1804
1805         function _block_header($xbeg, $xlen, $ybeg, $ylen) {
1806                 if ($xlen > 1)
1807                 $xbeg .= "," . ($xbeg + $xlen - 1);
1808                 if ($ylen > 1)
1809                 $ybeg .= "," . ($ybeg + $ylen - 1);
1810
1811                 return $xbeg . ($xlen ? ($ylen ? 'c' : 'd') : 'a') . $ybeg;
1812         }
1813
1814         function _start_block($header) {
1815                 echo $header . "\n";
1816         }
1817
1818         function _end_block() {
1819         }
1820
1821         function _lines($lines, $prefix = ' ') {
1822                 foreach ($lines as $line)
1823                 echo "$prefix $line\n";
1824         }
1825
1826         function _context($lines) {
1827                 $this->_lines($lines);
1828         }
1829
1830         function _added($lines) {
1831                 $this->_lines($lines, '>');
1832         }
1833         function _deleted($lines) {
1834                 $this->_lines($lines, '<');
1835         }
1836
1837         function _changed($orig, $closing) {
1838                 $this->_deleted($orig);
1839                 echo "---\n";
1840                 $this->_added($closing);
1841         }
1842 }
1843
1844 /**
1845  * A formatter that outputs unified diffs
1846  * @ingroup DifferenceEngine
1847  */
1848
1849 class UnifiedDiffFormatter extends DiffFormatter {
1850         var $leading_context_lines = 2;
1851         var $trailing_context_lines = 2;
1852
1853         function _added($lines) {
1854                 $this->_lines($lines, '+');
1855         }
1856         function _deleted($lines) {
1857                 $this->_lines($lines, '-');
1858         }
1859         function _changed($orig, $closing) {
1860                 $this->_deleted($orig);
1861                 $this->_added($closing);
1862         }
1863         function _block_header($xbeg, $xlen, $ybeg, $ylen) {
1864                 return "@@ -$xbeg,$xlen +$ybeg,$ylen @@";
1865         }
1866 }
1867
1868 /**
1869  * A pseudo-formatter that just passes along the Diff::$edits array
1870  * @ingroup DifferenceEngine
1871  */
1872 class ArrayDiffFormatter extends DiffFormatter {
1873         function format($diff) {
1874                 $oldline = 1;
1875                 $newline = 1;
1876                 $retval = array();
1877                 foreach($diff->edits as $edit)
1878                 switch($edit->type) {
1879                         case 'add':
1880                                 foreach($edit->closing as $l) {
1881                                         $retval[] = array(
1882                                                         'action' => 'add',
1883                                                         'new'=> $l,
1884                                                         'newline' => $newline++
1885                                         );
1886                                 }
1887                                 break;
1888                         case 'delete':
1889                                 foreach($edit->orig as $l) {
1890                                         $retval[] = array(
1891                                                         'action' => 'delete',
1892                                                         'old' => $l,
1893                                                         'oldline' => $oldline++,
1894                                         );
1895                                 }
1896                                 break;
1897                         case 'change':
1898                                 foreach($edit->orig as $i => $l) {
1899                                         $retval[] = array(
1900                                                         'action' => 'change',
1901                                                         'old' => $l,
1902                                                         'new' => @$edit->closing[$i],
1903                                                         'oldline' => $oldline++,
1904                                                         'newline' => $newline++,
1905                                         );
1906                                 }
1907                                 break;
1908                         case 'copy':
1909                                 $oldline += count($edit->orig);
1910                                 $newline += count($edit->orig);
1911                 }
1912                 return $retval;
1913         }
1914 }
1915
1916 /**
1917  *      Additions by Axel Boldt follow, partly taken from diff.php, phpwiki-1.3.3
1918  *
1919  */
1920
1921 define('NBSP', '&#160;'); // iso-8859-x non-breaking space.
1922
1923 /**
1924  * @todo document
1925  * @private
1926  * @ingroup DifferenceEngine
1927  */
1928 class _HWLDF_WordAccumulator {
1929         function _HWLDF_WordAccumulator () {
1930                 $this->_lines = array();
1931                 $this->_line = '';
1932                 $this->_group = '';
1933                 $this->_tag = '';
1934         }
1935
1936         function _flushGroup ($new_tag) {
1937                 if ($this->_group !== '') {
1938                         if ($this->_tag == 'ins')
1939                         $this->_line .= '<ins class="diffchange diffchange-inline">' .
1940                         htmlspecialchars ( $this->_group ) . '</ins>';
1941                         elseif ($this->_tag == 'del')
1942                         $this->_line .= '<del class="diffchange diffchange-inline">' .
1943                         htmlspecialchars ( $this->_group ) . '</del>';
1944                         else
1945                         $this->_line .= htmlspecialchars ( $this->_group );
1946                 }
1947                 $this->_group = '';
1948                 $this->_tag = $new_tag;
1949         }
1950
1951         function _flushLine ($new_tag) {
1952                 $this->_flushGroup($new_tag);
1953                 if ($this->_line != '')
1954                 array_push ( $this->_lines, $this->_line );
1955                 else
1956                 # make empty lines visible by inserting an NBSP
1957                 array_push ( $this->_lines, NBSP );
1958                 $this->_line = '';
1959         }
1960
1961         function addWords ($words, $tag = '') {
1962                 if ($tag != $this->_tag)
1963                 $this->_flushGroup($tag);
1964
1965                 foreach ($words as $word) {
1966                         // new-line should only come as first char of word.
1967                         if ($word == '')
1968                         continue;
1969                         if ($word[0] == "\n") {
1970                                 $this->_flushLine($tag);
1971                                 $word = substr($word, 1);
1972                         }
1973                         assert(!strstr($word, "\n"));
1974                         $this->_group .= $word;
1975                 }
1976         }
1977
1978         function getLines() {
1979                 $this->_flushLine('~done');
1980                 return $this->_lines;
1981         }
1982 }
1983
1984 /**
1985  * @todo document
1986  * @private
1987  * @ingroup DifferenceEngine
1988  */
1989 class WordLevelDiff extends MappedDiff {
1990         const MAX_LINE_LENGTH = 10000;
1991
1992         function WordLevelDiff ($orig_lines, $closing_lines) {
1993                 wfProfileIn( __METHOD__ );
1994
1995                 list ($orig_words, $orig_stripped) = $this->_split($orig_lines);
1996                 list ($closing_words, $closing_stripped) = $this->_split($closing_lines);
1997
1998                 $this->MappedDiff($orig_words, $closing_words,
1999                 $orig_stripped, $closing_stripped);
2000                 wfProfileOut( __METHOD__ );
2001         }
2002
2003         function _split($lines) {
2004                 wfProfileIn( __METHOD__ );
2005
2006                 $words = array();
2007                 $stripped = array();
2008                 $first = true;
2009                 foreach ( $lines as $line ) {
2010                         # If the line is too long, just pretend the entire line is one big word
2011                         # This prevents resource exhaustion problems
2012                         if ( $first ) {
2013                                 $first = false;
2014                         } else {
2015                                 $words[] = "\n";
2016                                 $stripped[] = "\n";
2017                         }
2018                         if ( strlen( $line ) > self::MAX_LINE_LENGTH ) {
2019                                 $words[] = $line;
2020                                 $stripped[] = $line;
2021                         } else {
2022                                 $m = array();
2023                                 if (preg_match_all('/ ( [^\S\n]+ | [0-9_A-Za-z\x80-\xff]+ | . ) (?: (?!< \n) [^\S\n])? /xs',
2024                                 $line, $m))
2025                                 {
2026                                         $words = array_merge( $words, $m[0] );
2027                                         $stripped = array_merge( $stripped, $m[1] );
2028                                 }
2029                         }
2030                 }
2031                 wfProfileOut( __METHOD__ );
2032                 return array($words, $stripped);
2033         }
2034
2035         function orig () {
2036                 wfProfileIn( __METHOD__ );
2037                 $orig = new _HWLDF_WordAccumulator;
2038
2039                 foreach ($this->edits as $edit) {
2040                         if ($edit->type == 'copy')
2041                         $orig->addWords($edit->orig);
2042                         elseif ($edit->orig)
2043                         $orig->addWords($edit->orig, 'del');
2044                 }
2045                 $lines = $orig->getLines();
2046                 wfProfileOut( __METHOD__ );
2047                 return $lines;
2048         }
2049
2050         function closing () {
2051                 wfProfileIn( __METHOD__ );
2052                 $closing = new _HWLDF_WordAccumulator;
2053
2054                 foreach ($this->edits as $edit) {
2055                         if ($edit->type == 'copy')
2056                         $closing->addWords($edit->closing);
2057                         elseif ($edit->closing)
2058                         $closing->addWords($edit->closing, 'ins');
2059                 }
2060                 $lines = $closing->getLines();
2061                 wfProfileOut( __METHOD__ );
2062                 return $lines;
2063         }
2064 }
2065
2066 /**
2067  * Wikipedia Table style diff formatter.
2068  * @todo document
2069  * @private
2070  * @ingroup DifferenceEngine
2071  */
2072 class TableDiffFormatter extends DiffFormatter {
2073         function TableDiffFormatter() {
2074                 $this->leading_context_lines = 2;
2075                 $this->trailing_context_lines = 2;
2076         }
2077
2078         public static function escapeWhiteSpace( $msg ) {
2079                 $msg = preg_replace( '/^ /m', '&nbsp; ', $msg );
2080                 $msg = preg_replace( '/ $/m', ' &nbsp;', $msg );
2081                 $msg = preg_replace( '/  /', '&nbsp; ', $msg );
2082                 return $msg;
2083         }
2084
2085         function _block_header( $xbeg, $xlen, $ybeg, $ylen ) {
2086                 $r = '<tr><td colspan="2" class="diff-lineno"><!--LINE '.$xbeg."--></td>\n" .
2087                   '<td colspan="2" class="diff-lineno"><!--LINE '.$ybeg."--></td></tr>\n";
2088                 return $r;
2089         }
2090
2091         function _start_block( $header ) {
2092                 echo $header;
2093         }
2094
2095         function _end_block() {
2096         }
2097
2098         function _lines( $lines, $prefix=' ', $color='white' ) {
2099         }
2100
2101         # HTML-escape parameter before calling this
2102         function addedLine( $line ) {
2103                 return $this->wrapLine( '+', 'diff-addedline', $line );
2104         }
2105
2106         # HTML-escape parameter before calling this
2107         function deletedLine( $line ) {
2108                 return $this->wrapLine( '-', 'diff-deletedline', $line );
2109         }
2110
2111         # HTML-escape parameter before calling this
2112         function contextLine( $line ) {
2113                 return $this->wrapLine( ' ', 'diff-context', $line );
2114         }
2115
2116         private function wrapLine( $marker, $class, $line ) {
2117                 if( $line !== '' ) {
2118                         // The <div> wrapper is needed for 'overflow: auto' style to scroll properly
2119                         $line = Xml::tags( 'div', null, $this->escapeWhiteSpace( $line ) );
2120                 }
2121                 return "<td class='diff-marker'>$marker</td><td class='$class'>$line</td>";
2122         }
2123
2124         function emptyLine() {
2125                 return '<td colspan="2">&nbsp;</td>';
2126         }
2127
2128         function _added( $lines ) {
2129                 foreach ($lines as $line) {
2130                         echo '<tr>' . $this->emptyLine() .
2131                         $this->addedLine( '<ins class="diffchange">' .
2132                         htmlspecialchars ( $line ) . '</ins>' ) . "</tr>\n";
2133                 }
2134         }
2135
2136         function _deleted($lines) {
2137                 foreach ($lines as $line) {
2138                         echo '<tr>' . $this->deletedLine( '<del class="diffchange">' .
2139                         htmlspecialchars ( $line ) . '</del>' ) .
2140                         $this->emptyLine() . "</tr>\n";
2141                 }
2142         }
2143
2144         function _context( $lines ) {
2145                 foreach ($lines as $line) {
2146                         echo '<tr>' .
2147                         $this->contextLine( htmlspecialchars ( $line ) ) .
2148                         $this->contextLine( htmlspecialchars ( $line ) ) . "</tr>\n";
2149                 }
2150         }
2151
2152         function _changed( $orig, $closing ) {
2153                 wfProfileIn( __METHOD__ );
2154
2155                 $diff = new WordLevelDiff( $orig, $closing );
2156                 $del = $diff->orig();
2157                 $add = $diff->closing();
2158
2159                 # Notice that WordLevelDiff returns HTML-escaped output.
2160                 # Hence, we will be calling addedLine/deletedLine without HTML-escaping.
2161
2162                 while ( $line = array_shift( $del ) ) {
2163                         $aline = array_shift( $add );
2164                         echo '<tr>' . $this->deletedLine( $line ) .
2165                         $this->addedLine( $aline ) . "</tr>\n";
2166                 }
2167                 foreach ($add as $line) {       # If any leftovers
2168                         echo '<tr>' . $this->emptyLine() .
2169                         $this->addedLine( $line ) . "</tr>\n";
2170                 }
2171                 wfProfileOut( __METHOD__ );
2172         }
2173 }