includes/diff/DifferenceEngine.php

   1 <?php
   2 /**
   3  * User interface for the difference engine.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  * @ingroup DifferenceEngine
  22  */
  23
  24 /**
  25  * Constant to indicate diff cache compatibility.
  26  * Bump this when changing the diff formatting in a way that
  27  * fixes important bugs or such to force cached diff views to
  28  * clear.
  29  */
  30 define( 'MW_DIFF_VERSION', '1.11a' );
  31
  32 /**
  33  * @todo document
  34  * @ingroup DifferenceEngine
  35  */
  36 class DifferenceEngine extends ContextSource {
  37         /**#@+
  38          * @private
  39          */
  40         var $mOldid, $mNewid;
  41         var $mOldTags, $mNewTags;
  42         /**
  43          * @var Content
  44          */
  45         var $mOldContent, $mNewContent;
  46         protected $mDiffLang;
  47
  48         /**
  49          * @var Title
  50          */
  51         var $mOldPage, $mNewPage;
  52
  53         /**
  54          * @var Revision
  55          */
  56         var $mOldRev, $mNewRev;
  57         private $mRevisionsIdsLoaded = false; // Have the revisions IDs been loaded
  58         var $mRevisionsLoaded = false; // Have the revisions been loaded
  59         var $mTextLoaded = 0; // How many text blobs have been loaded, 0, 1 or 2?
  60         var $mCacheHit = false; // Was the diff fetched from cache?
  61
  62         /**
  63          * Set this to true to add debug info to the HTML output.
  64          * Warning: this may cause RSS readers to spuriously mark articles as "new"
  65          * (bug 20601)
  66          */
  67         var $enableDebugComment = false;
  68
  69         // If true, line X is not displayed when X is 1, for example to increase
  70         // readability and conserve space with many small diffs.
  71         protected $mReducedLineNumbers = false;
  72
  73         // Link to action=markpatrolled
  74         protected $mMarkPatrolledLink = null;
  75
  76         protected $unhide = false; # show rev_deleted content if allowed
  77         /**#@-*/
  78
  79         /**
  80          * Constructor
  81          * @param $context IContextSource context to use, anything else will be ignored
  82          * @param $old Integer old ID we want to show and diff with.
  83          * @param $new String either 'prev' or 'next'.
  84          * @param $rcid Integer Deprecated, no longer used!
  85          * @param $refreshCache boolean If set, refreshes the diff cache
  86          * @param $unhide boolean If set, allow viewing deleted revs
  87          */
  88         function __construct( $context = null, $old = 0, $new = 0, $rcid = 0,
  89                 $refreshCache = false, $unhide = false )
  90         {
  91                 if ( $context instanceof IContextSource ) {
  92                         $this->setContext( $context );
  93                 }
  94
  95                 wfDebug( "DifferenceEngine old '$old' new '$new' rcid '$rcid'\n" );
  96
  97                 $this->mOldid = $old;
  98                 $this->mNewid = $new;
  99                 $this->mRefreshCache = $refreshCache;
 100                 $this->unhide = $unhide;
 101         }
 102
 103         /**
 104          * @param $value bool
 105          */
 106         function setReducedLineNumbers( $value = true ) {
 107                 $this->mReducedLineNumbers = $value;
 108         }
 109
 110         /**
 111          * @return Language
 112          */
 113         function getDiffLang() {
 114                 if ( $this->mDiffLang === null ) {
 115                         # Default language in which the diff text is written.
 116                         $this->mDiffLang = $this->getTitle()->getPageLanguage();
 117                 }
 118                 return $this->mDiffLang;
 119         }
 120
 121         /**
 122          * @return bool
 123          */
 124         function wasCacheHit() {
 125                 return $this->mCacheHit;
 126         }
 127
 128         /**
 129          * @return int
 130          */
 131         function getOldid() {
 132                 $this->loadRevisionIds();
 133                 return $this->mOldid;
 134         }
 135
 136         /**
 137          * @return Bool|int
 138          */
 139         function getNewid() {
 140                 $this->loadRevisionIds();
 141                 return $this->mNewid;
 142         }
 143
 144         /**
 145          * Look up a special:Undelete link to the given deleted revision id,
 146          * as a workaround for being unable to load deleted diffs in currently.
 147          *
 148          * @param int $id revision ID
 149          * @return mixed URL or false
 150          */
 151         function deletedLink( $id ) {
 152                 if ( $this->getUser()->isAllowed( 'deletedhistory' ) ) {
 153                         $dbr = wfGetDB( DB_SLAVE );
 154                         $row = $dbr->selectRow( 'archive', '*',
 155                                 array( 'ar_rev_id' => $id ),
 156                                 __METHOD__ );
 157                         if ( $row ) {
 158                                 $rev = Revision::newFromArchiveRow( $row );
 159                                 $title = Title::makeTitleSafe( $row->ar_namespace, $row->ar_title );
 160                                 return SpecialPage::getTitleFor( 'Undelete' )->getFullURL( array(
 161                                         'target' => $title->getPrefixedText(),
 162                                         'timestamp' => $rev->getTimestamp()
 163                                 ));
 164                         }
 165                 }
 166                 return false;
 167         }
 168
 169         /**
 170          * Build a wikitext link toward a deleted revision, if viewable.
 171          *
 172          * @param int $id revision ID
 173          * @return string wikitext fragment
 174          */
 175         function deletedIdMarker( $id ) {
 176                 $link = $this->deletedLink( $id );
 177                 if ( $link ) {
 178                         return "[$link $id]";
 179                 } else {
 180                         return $id;
 181                 }
 182         }
 183
 184         private function showMissingRevision() {
 185                 $out = $this->getOutput();
 186
 187                 $missing = array();
 188                 if ( $this->mOldRev === null ||
 189                         ( $this->mOldRev && $this->mOldContent === null )
 190                 ) {
 191                         $missing[] = $this->deletedIdMarker( $this->mOldid );
 192                 }
 193                 if ( $this->mNewRev === null ||
 194                         ( $this->mNewRev && $this->mNewContent === null )
 195                 ) {
 196                         $missing[] = $this->deletedIdMarker( $this->mNewid );
 197                 }
 198
 199                 $out->setPageTitle( $this->msg( 'errorpagetitle' ) );
 200                 $out->addWikiMsg( 'difference-missing-revision',
 201                         $this->getLanguage()->listToText( $missing ), count( $missing ) );
 202         }
 203
 204         function showDiffPage( $diffOnly = false ) {
 205                 wfProfileIn( __METHOD__ );
 206
 207                 # Allow frames except in certain special cases
 208                 $out = $this->getOutput();
 209                 $out->allowClickjacking();
 210                 $out->setRobotPolicy( 'noindex,nofollow' );
 211
 212                 if ( !$this->loadRevisionData() ) {
 213                         $this->showMissingRevision();
 214                         wfProfileOut( __METHOD__ );
 215                         return;
 216                 }
 217
 218                 $user = $this->getUser();
 219                 $permErrors = $this->mNewPage->getUserPermissionsErrors( 'read', $user );
 220                 if ( $this->mOldPage ) { # mOldPage might not be set, see below.
 221                         $permErrors = wfMergeErrorArrays( $permErrors,
 222                                 $this->mOldPage->getUserPermissionsErrors( 'read', $user ) );
 223                 }
 224                 if ( count( $permErrors ) ) {
 225                         wfProfileOut( __METHOD__ );
 226                         throw new PermissionsError( 'read', $permErrors );
 227                 }
 228
 229                 $rollback = '';
 230                 $undoLink = '';
 231
 232                 $query = array();
 233                 # Carry over 'diffonly' param via navigation links
 234                 if ( $diffOnly != $user->getBoolOption( 'diffonly' ) ) {
 235                         $query['diffonly'] = $diffOnly;
 236                 }
 237                 # Cascade unhide param in links for easy deletion browsing
 238                 if ( $this->unhide ) {
 239                         $query['unhide'] = 1;
 240                 }
 241
 242                 # Check if one of the revisions is deleted/suppressed
 243                 $deleted = $suppressed = false;
 244                 $allowed = $this->mNewRev->userCan( Revision::DELETED_TEXT, $user );
 245
 246                 $revisionTools = array();
 247
 248                 # mOldRev is false if the difference engine is called with a "vague" query for
 249                 # a diff between a version V and its previous version V' AND the version V
 250                 # is the first version of that article. In that case, V' does not exist.
 251                 if ( $this->mOldRev === false ) {
 252                         $out->setPageTitle( $this->msg( 'difference-title', $this->mNewPage->getPrefixedText() ) );
 253                         $samePage = true;
 254                         $oldHeader = '';
 255                 } else {
 256                         wfRunHooks( 'DiffViewHeader', array( $this, $this->mOldRev, $this->mNewRev ) );
 257
 258                         if ( $this->mNewPage->equals( $this->mOldPage ) ) {
 259                                 $out->setPageTitle( $this->msg( 'difference-title', $this->mNewPage->getPrefixedText() ) );
 260                                 $samePage = true;
 261                         } else {
 262                                 $out->setPageTitle( $this->msg( 'difference-title-multipage', $this->mOldPage->getPrefixedText(),
 263                                         $this->mNewPage->getPrefixedText() ) );
 264                                 $out->addSubtitle( $this->msg( 'difference-multipage' ) );
 265                                 $samePage = false;
 266                         }
 267
 268                         if ( $samePage && $this->mNewPage->quickUserCan( 'edit', $user ) ) {
 269                                 if ( $this->mNewRev->isCurrent() && $this->mNewPage->userCan( 'rollback', $user ) ) {
 270                                         $rollbackLink = Linker::generateRollback( $this->mNewRev, $this->getContext() );
 271                                         if ( $rollbackLink ) {
 272                                                 $out->preventClickjacking();
 273                                                 $rollback = '&#160;&#160;&#160;' . $rollbackLink;
 274                                         }
 275                                 }
 276                                 if ( !$this->mOldRev->isDeleted( Revision::DELETED_TEXT ) && !$this->mNewRev->isDeleted( Revision::DELETED_TEXT ) ) {
 277                                         $undoLink = Html::element( 'a', array(
 278                                                         'href' => $this->mNewPage->getLocalURL( array(
 279                                                                 'action' => 'edit',
 280                                                                 'undoafter' => $this->mOldid,
 281                                                                 'undo' => $this->mNewid ) ),
 282                                                         'title' => Linker::titleAttrib( 'undo' )
 283                                                 ),
 284                                                 $this->msg( 'editundo' )->text()
 285                                         );
 286                                         $revisionTools[] = $undoLink;
 287                                 }
 288                         }
 289
 290                         # Make "previous revision link"
 291                         if ( $samePage && $this->mOldRev->getPrevious() ) {
 292                                 $prevlink = Linker::linkKnown(
 293                                         $this->mOldPage,
 294                                         $this->msg( 'previousdiff' )->escaped(),
 295                                         array( 'id' => 'differences-prevlink' ),
 296                                         array( 'diff' => 'prev', 'oldid' => $this->mOldid ) + $query
 297                                 );
 298                         } else {
 299                                 $prevlink = '&#160;';
 300                         }
 301
 302                         if ( $this->mOldRev->isMinor() ) {
 303                                 $oldminor = ChangesList::flag( 'minor' );
 304                         } else {
 305                                 $oldminor = '';
 306                         }
 307
 308                         $ldel = $this->revisionDeleteLink( $this->mOldRev );
 309                         $oldRevisionHeader = $this->getRevisionHeader( $this->mOldRev, 'complete' );
 310                         $oldChangeTags = ChangeTags::formatSummaryRow( $this->mOldTags, 'diff' );
 311
 312                         $oldHeader = '<div id="mw-diff-otitle1"><strong>' . $oldRevisionHeader . '</strong></div>' .
 313                                 '<div id="mw-diff-otitle2">' .
 314                                         Linker::revUserTools( $this->mOldRev, !$this->unhide ) . '</div>' .
 315                                 '<div id="mw-diff-otitle3">' . $oldminor .
 316                                         Linker::revComment( $this->mOldRev, !$diffOnly, !$this->unhide ) . $ldel . '</div>' .
 317                                 '<div id="mw-diff-otitle5">' . $oldChangeTags[0] . '</div>' .
 318                                 '<div id="mw-diff-otitle4">' . $prevlink . '</div>';
 319
 320                         if ( $this->mOldRev->isDeleted( Revision::DELETED_TEXT ) ) {
 321                                 $deleted = true; // old revisions text is hidden
 322                                 if ( $this->mOldRev->isDeleted( Revision::DELETED_RESTRICTED ) ) {
 323                                         $suppressed = true; // also suppressed
 324                                 }
 325                         }
 326
 327                         # Check if this user can see the revisions
 328                         if ( !$this->mOldRev->userCan( Revision::DELETED_TEXT, $user ) ) {
 329                                 $allowed = false;
 330                         }
 331                 }
 332
 333                 # Make "next revision link"
 334                 # Skip next link on the top revision
 335                 if ( $samePage && !$this->mNewRev->isCurrent() ) {
 336                         $nextlink = Linker::linkKnown(
 337                                 $this->mNewPage,
 338                                 $this->msg( 'nextdiff' )->escaped(),
 339                                 array( 'id' => 'differences-nextlink' ),
 340                                 array( 'diff' => 'next', 'oldid' => $this->mNewid ) + $query
 341                         );
 342                 } else {
 343                         $nextlink = '&#160;';
 344                 }
 345
 346                 if ( $this->mNewRev->isMinor() ) {
 347                         $newminor = ChangesList::flag( 'minor' );
 348                 } else {
 349                         $newminor = '';
 350                 }
 351
 352                 # Handle RevisionDelete links...
 353                 $rdel = $this->revisionDeleteLink( $this->mNewRev );
 354
 355                 # Allow extensions to define their own revision tools
 356                 wfRunHooks( 'DiffRevisionTools', array( $this->mNewRev, &$revisionTools ) );
 357                 $formattedRevisionTools = array();
 358                 // Put each one in parentheses (poor man's button)
 359                 foreach ( $revisionTools as $tool ) {
 360                         $formattedRevisionTools[] = $this->msg( 'parentheses' )->rawParams( $tool )->escaped();
 361                 }
 362                 $newRevisionHeader = $this->getRevisionHeader( $this->mNewRev, 'complete' ) . ' ' . implode( ' ', $formattedRevisionTools );
 363                 $newChangeTags = ChangeTags::formatSummaryRow( $this->mNewTags, 'diff' );
 364
 365                 $newHeader = '<div id="mw-diff-ntitle1"><strong>' . $newRevisionHeader . '</strong></div>' .
 366                         '<div id="mw-diff-ntitle2">' . Linker::revUserTools( $this->mNewRev, !$this->unhide ) .
 367                                 " $rollback</div>" .
 368                         '<div id="mw-diff-ntitle3">' . $newminor .
 369                                 Linker::revComment( $this->mNewRev, !$diffOnly, !$this->unhide ) . $rdel . '</div>' .
 370                         '<div id="mw-diff-ntitle5">' . $newChangeTags[0] . '</div>' .
 371                         '<div id="mw-diff-ntitle4">' . $nextlink . $this->markPatrolledLink() . '</div>';
 372
 373                 if ( $this->mNewRev->isDeleted( Revision::DELETED_TEXT ) ) {
 374                         $deleted = true; // new revisions text is hidden
 375                         if ( $this->mNewRev->isDeleted( Revision::DELETED_RESTRICTED ) ) {
 376                                 $suppressed = true; // also suppressed
 377                         }
 378                 }
 379
 380                 # If the diff cannot be shown due to a deleted revision, then output
 381                 # the diff header and links to unhide (if available)...
 382                 if ( $deleted && ( !$this->unhide || !$allowed ) ) {
 383                         $this->showDiffStyle();
 384                         $multi = $this->getMultiNotice();
 385                         $out->addHTML( $this->addHeader( '', $oldHeader, $newHeader, $multi ) );
 386                         if ( !$allowed ) {
 387                                 $msg = $suppressed ? 'rev-suppressed-no-diff' : 'rev-deleted-no-diff';
 388                                 # Give explanation for why revision is not visible
 389                                 $out->wrapWikiMsg( "<div id='mw-$msg' class='mw-warning plainlinks'>\n$1\n</div>\n",
 390                                         array( $msg ) );
 391                         } else {
 392                                 # Give explanation and add a link to view the diff...
 393                                 $link = $this->getTitle()->getFullURL( $this->getRequest()->appendQueryValue( 'unhide', '1', true ) );
 394                                 $msg = $suppressed ? 'rev-suppressed-unhide-diff' : 'rev-deleted-unhide-diff';
 395                                 $out->wrapWikiMsg( "<div id='mw-$msg' class='mw-warning plainlinks'>\n$1\n</div>\n", array( $msg, $link ) );
 396                         }
 397                 # Otherwise, output a regular diff...
 398                 } else {
 399                         # Add deletion notice if the user is viewing deleted content
 400                         $notice = '';
 401                         if ( $deleted ) {
 402                                 $msg = $suppressed ? 'rev-suppressed-diff-view' : 'rev-deleted-diff-view';
 403                                 $notice = "<div id='mw-$msg' class='mw-warning plainlinks'>\n" . $this->msg( $msg )->parse() . "</div>\n";
 404                         }
 405                         $this->showDiff( $oldHeader, $newHeader, $notice );
 406                         if ( !$diffOnly ) {
 407                                 $this->renderNewRevision();
 408                         }
 409                 }
 410                 wfProfileOut( __METHOD__ );
 411         }
 412
 413         /**
 414          * Get a link to mark the change as patrolled, or '' if there's either no
 415          * revision to patrol or the user is not allowed to to it.
 416          * Side effect: When the patrol link is build, this method will call
 417          * OutputPage::preventClickjacking() and load mediawiki.page.patrol.ajax.
 418          *
 419          * @return String
 420          */
 421         protected function markPatrolledLink() {
 422                 global $wgUseRCPatrol, $wgEnableAPI, $wgEnableWriteAPI;
 423                 $user = $this->getUser();
 424
 425                 if ( $this->mMarkPatrolledLink === null ) {
 426                         // Prepare a change patrol link, if applicable
 427                         if (
 428                                 // Is patrolling enabled and the user allowed to?
 429                                 $wgUseRCPatrol && $this->mNewPage->quickUserCan( 'patrol', $user ) &&
 430                                 // Only do this if the revision isn't more than 6 hours older
 431                                 // than the Max RC age (6h because the RC might not be cleaned out regularly)
 432                                 RecentChange::isInRCLifespan( $this->mNewRev->getTimestamp(), 21600 )
 433                         ) {
 434                                 // Look for an unpatrolled change corresponding to this diff
 435
 436                                 $db = wfGetDB( DB_SLAVE );
 437                                 $change = RecentChange::newFromConds(
 438                                         array(
 439                                                 'rc_timestamp' => $db->timestamp( $this->mNewRev->getTimestamp() ),
 440                                                 'rc_this_oldid' => $this->mNewid,
 441                                                 'rc_patrolled' => 0
 442                                         ),
 443                                         __METHOD__,
 444                                         array( 'USE INDEX' => 'rc_timestamp' )
 445                                 );
 446
 447                                 if ( $change && $change->getPerformer()->getName() !== $user->getName() ) {
 448                                         $rcid = $change->getAttribute( 'rc_id' );
 449                                 } else {
 450                                         // None found or the page has been created by the current user.
 451                                         // If the user could patrol this it already would be patrolled
 452                                         $rcid = 0;
 453                                 }
 454                                 // Build the link
 455                                 if ( $rcid ) {
 456                                         $this->getOutput()->preventClickjacking();
 457                                         if ( $wgEnableAPI && $wgEnableWriteAPI
 458                                                 && $user->isAllowed( 'writeapi' )
 459                                         ) {
 460                                                 $this->getOutput()->addModules( 'mediawiki.page.patrol.ajax' );
 461                                         }
 462
 463                                         $token = $user->getEditToken( $rcid );
 464                                         $this->mMarkPatrolledLink = ' <span class="patrollink">[' . Linker::linkKnown(
 465                                                 $this->mNewPage,
 466                                                 $this->msg( 'markaspatrolleddiff' )->escaped(),
 467                                                 array(),
 468                                                 array(
 469                                                         'action' => 'markpatrolled',
 470                                                         'rcid' => $rcid,
 471                                                         'token' => $token,
 472                                                 )
 473                                         ) . ']</span>';
 474                                 } else {
 475                                         $this->mMarkPatrolledLink = '';
 476                                 }
 477                         } else {
 478                                 $this->mMarkPatrolledLink = '';
 479                         }
 480                 }
 481
 482                 return $this->mMarkPatrolledLink;
 483         }
 484
 485         /**
 486          * @param $rev Revision
 487          * @return String
 488          */
 489         protected function revisionDeleteLink( $rev ) {
 490                 $link = Linker::getRevDeleteLink( $this->getUser(), $rev, $rev->getTitle() );
 491                 if ( $link !== '' ) {
 492                         $link = '&#160;&#160;&#160;' . $link . ' ';
 493                 }
 494                 return $link;
 495         }
 496
 497         /**
 498          * Show the new revision of the page.
 499          */
 500         function renderNewRevision() {
 501                 wfProfileIn( __METHOD__ );
 502                 $out = $this->getOutput();
 503                 $revHeader = $this->getRevisionHeader( $this->mNewRev );
 504                 # Add "current version as of X" title
 505                 $out->addHTML( "<hr class='diff-hr' />
 506                 <h2 class='diff-currentversion-title'>{$revHeader}</h2>\n" );
 507                 # Page content may be handled by a hooked call instead...
 508                 if ( wfRunHooks( 'ArticleContentOnDiff', array( $this, $out ) ) ) {
 509                         $this->loadNewText();
 510                         $out->setRevisionId( $this->mNewid );
 511                         $out->setRevisionTimestamp( $this->mNewRev->getTimestamp() );
 512                         $out->setArticleFlag( true );
 513
 514                         // NOTE: only needed for B/C: custom rendering of JS/CSS via hook
 515                         if ( $this->mNewPage->isCssJsSubpage() || $this->mNewPage->isCssOrJsPage() ) {
 516                                 // Stolen from Article::view --AG 2007-10-11
 517                                 // Give hooks a chance to customise the output
 518                                 // @todo standardize this crap into one function
 519                                 if ( ContentHandler::runLegacyHooks( 'ShowRawCssJs', array( $this->mNewContent, $this->mNewPage, $out ) ) ) {
 520                                         // NOTE: deprecated hook, B/C only
 521                                         // use the content object's own rendering
 522                                         $cnt = $this->mNewRev->getContent();
 523                                         $po = $cnt ? $cnt->getParserOutput( $this->mNewRev->getTitle(), $this->mNewRev->getId() ) : null;
 524                                         $txt = $po ? $po->getText() : '';
 525                                         $out->addHTML( $txt );
 526                                 }
 527                         } elseif ( !wfRunHooks( 'ArticleContentViewCustom', array( $this->mNewContent, $this->mNewPage, $out ) ) ) {
 528                                 // Handled by extension
 529                         } elseif ( !ContentHandler::runLegacyHooks( 'ArticleViewCustom', array( $this->mNewContent, $this->mNewPage, $out ) ) ) {
 530                                 // NOTE: deprecated hook, B/C only
 531                                 // Handled by extension
 532                         } else {
 533                                 // Normal page
 534                                 if ( $this->getTitle()->equals( $this->mNewPage ) ) {
 535                                         // If the Title stored in the context is the same as the one
 536                                         // of the new revision, we can use its associated WikiPage
 537                                         // object.
 538                                         $wikiPage = $this->getWikiPage();
 539                                 } else {
 540                                         // Otherwise we need to create our own WikiPage object
 541                                         $wikiPage = WikiPage::factory( $this->mNewPage );
 542                                 }
 543
 544                                 $parserOutput = $this->getParserOutput( $wikiPage, $this->mNewRev );
 545
 546                                 # Also try to load it as a redirect
 547                                 $rt = $this->mNewContent ? $this->mNewContent->getRedirectTarget() : null;
 548
 549                                 if ( $rt ) {
 550                                         $article = Article::newFromTitle( $this->mNewPage, $this->getContext() );
 551                                         $out->addHTML( $article->viewRedirect( $rt ) );
 552
 553                                         # WikiPage::getParserOutput() should not return false, but just in case
 554                                         if ( $parserOutput ) {
 555                                                 # Show categories etc.
 556                                                 $out->addParserOutputNoText( $parserOutput );
 557                                         }
 558                                 } elseif ( $parserOutput ) {
 559                                         $out->addParserOutput( $parserOutput );
 560                                 }
 561                         }
 562                 }
 563                 # Add redundant patrol link on bottom...
 564                 $out->addHTML( $this->markPatrolledLink() );
 565
 566                 wfProfileOut( __METHOD__ );
 567         }
 568
 569         protected function getParserOutput( WikiPage $page, Revision $rev ) {
 570                 $parserOptions = $page->makeParserOptions( $this->getContext() );
 571
 572                 if ( !$rev->isCurrent() || !$rev->getTitle()->quickUserCan( "edit" ) ) {
 573                         $parserOptions->setEditSection( false );
 574                 }
 575
 576                 $parserOutput = $page->getParserOutput( $parserOptions, $rev->getId() );
 577                 return $parserOutput;
 578         }
 579
 580         /**
 581          * Get the diff text, send it to the OutputPage object
 582          * Returns false if the diff could not be generated, otherwise returns true
 583          *
 584          * @return bool
 585          */
 586         function showDiff( $otitle, $ntitle, $notice = '' ) {
 587                 $diff = $this->getDiff( $otitle, $ntitle, $notice );
 588                 if ( $diff === false ) {
 589                         $this->showMissingRevision();
 590                         return false;
 591                 } else {
 592                         $this->showDiffStyle();
 593                         $this->getOutput()->addHTML( $diff );
 594                         return true;
 595                 }
 596         }
 597
 598         /**
 599          * Add style sheets and supporting JS for diff display.
 600          */
 601         function showDiffStyle() {
 602                 $this->getOutput()->addModuleStyles( 'mediawiki.action.history.diff' );
 603         }
 604
 605         /**
 606          * Get complete diff table, including header
 607          *
 608          * @param string|bool $otitle Header for old text or false
 609          * @param string|bool $ntitle Header for new text or false
 610          * @param string $notice HTML between diff header and body
 611          * @return mixed
 612          */
 613         function getDiff( $otitle, $ntitle, $notice = '' ) {
 614                 $body = $this->getDiffBody();
 615                 if ( $body === false ) {
 616                         return false;
 617                 } else {
 618                         $multi = $this->getMultiNotice();
 619                         // Display a message when the diff is empty
 620                         if ( $body === '' ) {
 621                                 $notice .= '<div class="mw-diff-empty">' . $this->msg( 'diff-empty' )->parse() . "</div>\n";
 622                         }
 623                         return $this->addHeader( $body, $otitle, $ntitle, $multi, $notice );
 624                 }
 625         }
 626
 627         /**
 628          * Get the diff table body, without header
 629          *
 630          * @return mixed (string/false)
 631          */
 632         public function getDiffBody() {
 633                 global $wgMemc;
 634                 wfProfileIn( __METHOD__ );
 635                 $this->mCacheHit = true;
 636                 // Check if the diff should be hidden from this user
 637                 if ( !$this->loadRevisionData() ) {
 638                         wfProfileOut( __METHOD__ );
 639                         return false;
 640                 } elseif ( $this->mOldRev && !$this->mOldRev->userCan( Revision::DELETED_TEXT, $this->getUser() ) ) {
 641                         wfProfileOut( __METHOD__ );
 642                         return false;
 643                 } elseif ( $this->mNewRev && !$this->mNewRev->userCan( Revision::DELETED_TEXT, $this->getUser() ) ) {
 644                         wfProfileOut( __METHOD__ );
 645                         return false;
 646                 }
 647                 // Short-circuit
 648                 if ( $this->mOldRev === false || ( $this->mOldRev && $this->mNewRev
 649                         && $this->mOldRev->getID() == $this->mNewRev->getID() ) )
 650                 {
 651                         wfProfileOut( __METHOD__ );
 652                         return '';
 653                 }
 654                 // Cacheable?
 655                 $key = false;
 656                 if ( $this->mOldid && $this->mNewid ) {
 657                         $key = wfMemcKey( 'diff', 'version', MW_DIFF_VERSION,
 658                                 'oldid', $this->mOldid, 'newid', $this->mNewid );
 659                         // Try cache
 660                         if ( !$this->mRefreshCache ) {
 661                                 $difftext = $wgMemc->get( $key );
 662                                 if ( $difftext ) {
 663                                         wfIncrStats( 'diff_cache_hit' );
 664                                         $difftext = $this->localiseLineNumbers( $difftext );
 665                                         $difftext .= "\n<!-- diff cache key $key -->\n";
 666                                         wfProfileOut( __METHOD__ );
 667                                         return $difftext;
 668                                 }
 669                         } // don't try to load but save the result
 670                 }
 671                 $this->mCacheHit = false;
 672
 673                 // Loadtext is permission safe, this just clears out the diff
 674                 if ( !$this->loadText() ) {
 675                         wfProfileOut( __METHOD__ );
 676                         return false;
 677                 }
 678
 679                 $difftext = $this->generateContentDiffBody( $this->mOldContent, $this->mNewContent );
 680
 681                 // Save to cache for 7 days
 682                 if ( !wfRunHooks( 'AbortDiffCache', array( &$this ) ) ) {
 683                         wfIncrStats( 'diff_uncacheable' );
 684                 } elseif ( $key !== false && $difftext !== false ) {
 685                         wfIncrStats( 'diff_cache_miss' );
 686                         $wgMemc->set( $key, $difftext, 7 * 86400 );
 687                 } else {
 688                         wfIncrStats( 'diff_uncacheable' );
 689                 }
 690                 // Replace line numbers with the text in the user's language
 691                 if ( $difftext !== false ) {
 692                         $difftext = $this->localiseLineNumbers( $difftext );
 693                 }
 694                 wfProfileOut( __METHOD__ );
 695                 return $difftext;
 696         }
 697
 698         /**
 699          * Make sure the proper modules are loaded before we try to
 700          * make the diff
 701          */
 702         private function initDiffEngines() {
 703                 global $wgExternalDiffEngine;
 704                 if ( $wgExternalDiffEngine == 'wikidiff' && !function_exists( 'wikidiff_do_diff' ) ) {
 705                         wfProfileIn( __METHOD__ . '-php_wikidiff.so' );
 706                         wfDl( 'php_wikidiff' );
 707                         wfProfileOut( __METHOD__ . '-php_wikidiff.so' );
 708                 }
 709                 elseif ( $wgExternalDiffEngine == 'wikidiff2' && !function_exists( 'wikidiff2_do_diff' ) ) {
 710                         wfProfileIn( __METHOD__ . '-php_wikidiff2.so' );
 711                         wfDl( 'wikidiff2' );
 712                         wfProfileOut( __METHOD__ . '-php_wikidiff2.so' );
 713                 }
 714         }
 715
 716         /**
 717          * Generate a diff, no caching.
 718          *
 719          * This implementation uses generateTextDiffBody() to generate a diff based on the default
 720          * serialization of the given Content objects. This will fail if $old or $new are not
 721          * instances of TextContent.
 722          *
 723          * Subclasses may override this to provide a different rendering for the diff,
 724          * perhaps taking advantage of the content's native form. This is required for all content
 725          * models that are not text based.
 726          *
 727          * @param $old Content: old content
 728          * @param $new Content: new content
 729          *
 730          * @return bool|string
 731          * @since 1.21
 732          * @throws MWException if $old or $new are not instances of TextContent.
 733          */
 734         function generateContentDiffBody( Content $old, Content $new ) {
 735                 if ( !( $old instanceof TextContent ) ) {
 736                         throw new MWException( "Diff not implemented for " . get_class( $old ) . "; "
 737                                         . "override generateContentDiffBody to fix this." );
 738                 }
 739
 740                 if ( !( $new instanceof TextContent ) ) {
 741                         throw new MWException( "Diff not implemented for " . get_class( $new ) . "; "
 742                                 . "override generateContentDiffBody to fix this." );
 743                 }
 744
 745                 $otext = $old->serialize();
 746                 $ntext = $new->serialize();
 747
 748                 return $this->generateTextDiffBody( $otext, $ntext );
 749         }
 750
 751         /**
 752          * Generate a diff, no caching
 753          *
 754          * @param string $otext old text, must be already segmented
 755          * @param string $ntext new text, must be already segmented
 756          * @return bool|string
 757          * @deprecated since 1.21, use generateContentDiffBody() instead!
 758          */
 759         function generateDiffBody( $otext, $ntext ) {
 760                 ContentHandler::deprecated( __METHOD__, "1.21" );
 761
 762                 return $this->generateTextDiffBody( $otext, $ntext );
 763         }
 764
 765         /**
 766          * Generate a diff, no caching
 767          *
 768          * @todo move this to TextDifferenceEngine, make DifferenceEngine abstract. At some point.
 769          *
 770          * @param string $otext old text, must be already segmented
 771          * @param string $ntext new text, must be already segmented
 772          * @return bool|string
 773          */
 774         function generateTextDiffBody( $otext, $ntext ) {
 775                 global $wgExternalDiffEngine, $wgContLang;
 776
 777                 wfProfileIn( __METHOD__ );
 778
 779                 $otext = str_replace( "\r\n", "\n", $otext );
 780                 $ntext = str_replace( "\r\n", "\n", $ntext );
 781
 782                 $this->initDiffEngines();
 783
 784                 if ( $wgExternalDiffEngine == 'wikidiff' && function_exists( 'wikidiff_do_diff' ) ) {
 785                         # For historical reasons, external diff engine expects
 786                         # input text to be HTML-escaped already
 787                         $otext = htmlspecialchars ( $wgContLang->segmentForDiff( $otext ) );
 788                         $ntext = htmlspecialchars ( $wgContLang->segmentForDiff( $ntext ) );
 789                         wfProfileOut( __METHOD__ );
 790                         return $wgContLang->unsegmentForDiff( wikidiff_do_diff( $otext, $ntext, 2 ) ) .
 791                         $this->debug( 'wikidiff1' );
 792                 }
 793
 794                 if ( $wgExternalDiffEngine == 'wikidiff2' && function_exists( 'wikidiff2_do_diff' ) ) {
 795                         # Better external diff engine, the 2 may some day be dropped
 796                         # This one does the escaping and segmenting itself
 797                         wfProfileIn( 'wikidiff2_do_diff' );
 798                         $text = wikidiff2_do_diff( $otext, $ntext, 2 );
 799                         $text .= $this->debug( 'wikidiff2' );
 800                         wfProfileOut( 'wikidiff2_do_diff' );
 801                         wfProfileOut( __METHOD__ );
 802                         return $text;
 803                 }
 804                 if ( $wgExternalDiffEngine != 'wikidiff3' && $wgExternalDiffEngine !== false ) {
 805                         # Diff via the shell
 806                         $tmpDir = wfTempDir();
 807                         $tempName1 = tempnam( $tmpDir, 'diff_' );
 808                         $tempName2 = tempnam( $tmpDir, 'diff_' );
 809
 810                         $tempFile1 = fopen( $tempName1, "w" );
 811                         if ( !$tempFile1 ) {
 812                                 wfProfileOut( __METHOD__ );
 813                                 return false;
 814                         }
 815                         $tempFile2 = fopen( $tempName2, "w" );
 816                         if ( !$tempFile2 ) {
 817                                 wfProfileOut( __METHOD__ );
 818                                 return false;
 819                         }
 820                         fwrite( $tempFile1, $otext );
 821                         fwrite( $tempFile2, $ntext );
 822                         fclose( $tempFile1 );
 823                         fclose( $tempFile2 );
 824                         $cmd = wfEscapeShellArg( $wgExternalDiffEngine, $tempName1, $tempName2 );
 825                         wfProfileIn( __METHOD__ . "-shellexec" );
 826                         $difftext = wfShellExec( $cmd );
 827                         $difftext .= $this->debug( "external $wgExternalDiffEngine" );
 828                         wfProfileOut( __METHOD__ . "-shellexec" );
 829                         unlink( $tempName1 );
 830                         unlink( $tempName2 );
 831                         wfProfileOut( __METHOD__ );
 832                         return $difftext;
 833                 }
 834
 835                 # Native PHP diff
 836                 $ota = explode( "\n", $wgContLang->segmentForDiff( $otext ) );
 837                 $nta = explode( "\n", $wgContLang->segmentForDiff( $ntext ) );
 838                 $diffs = new Diff( $ota, $nta );
 839                 $formatter = new TableDiffFormatter();
 840                 $difftext = $wgContLang->unsegmentForDiff( $formatter->format( $diffs ) ) .
 841                 wfProfileOut( __METHOD__ );
 842                 return $difftext;
 843         }
 844
 845         /**
 846          * Generate a debug comment indicating diff generating time,
 847          * server node, and generator backend.
 848          * @return string
 849          */
 850         protected function debug( $generator = "internal" ) {
 851                 global $wgShowHostnames;
 852                 if ( !$this->enableDebugComment ) {
 853                         return '';
 854                 }
 855                 $data = array( $generator );
 856                 if ( $wgShowHostnames ) {
 857                         $data[] = wfHostname();
 858                 }
 859                 $data[] = wfTimestamp( TS_DB );
 860                 return "<!-- diff generator: " .
 861                 implode( " ",
 862                 array_map(
 863                                         "htmlspecialchars",
 864                 $data ) ) .
 865                         " -->\n";
 866         }
 867
 868         /**
 869          * Replace line numbers with the text in the user's language
 870          * @return mixed
 871          */
 872         function localiseLineNumbers( $text ) {
 873                 return preg_replace_callback( '/<!--LINE (\d+)-->/',
 874                 array( &$this, 'localiseLineNumbersCb' ), $text );
 875         }
 876
 877         function localiseLineNumbersCb( $matches ) {
 878                 if ( $matches[1] === '1' && $this->mReducedLineNumbers ) {
 879                         return '';
 880                 }
 881                 return $this->msg( 'lineno' )->numParams( $matches[1] )->escaped();
 882         }
 883
 884         /**
 885          * If there are revisions between the ones being compared, return a note saying so.
 886          * @return string
 887          */
 888         function getMultiNotice() {
 889                 if ( !is_object( $this->mOldRev ) || !is_object( $this->mNewRev ) ) {
 890                         return '';
 891                 } elseif ( !$this->mOldPage->equals( $this->mNewPage ) ) {
 892                         // Comparing two different pages? Count would be meaningless.
 893                         return '';
 894                 }
 895
 896                 if ( $this->mOldRev->getTimestamp() > $this->mNewRev->getTimestamp() ) {
 897                         $oldRev = $this->mNewRev; // flip
 898                         $newRev = $this->mOldRev; // flip
 899                 } else { // normal case
 900                         $oldRev = $this->mOldRev;
 901                         $newRev = $this->mNewRev;
 902                 }
 903
 904                 $nEdits = $this->mNewPage->countRevisionsBetween( $oldRev, $newRev );
 905                 if ( $nEdits > 0 ) {
 906                         $limit = 100; // use diff-multi-manyusers if too many users
 907                         $numUsers = $this->mNewPage->countAuthorsBetween( $oldRev, $newRev, $limit );
 908                         return self::intermediateEditsMsg( $nEdits, $numUsers, $limit );
 909                 }
 910                 return ''; // nothing
 911         }
 912
 913         /**
 914          * Get a notice about how many intermediate edits and users there are
 915          * @param $numEdits int
 916          * @param $numUsers int
 917          * @param $limit int
 918          * @return string
 919          */
 920         public static function intermediateEditsMsg( $numEdits, $numUsers, $limit ) {
 921                 if ( $numUsers > $limit ) {
 922                         $msg = 'diff-multi-manyusers';
 923                         $numUsers = $limit;
 924                 } else {
 925                         $msg = 'diff-multi';
 926                 }
 927                 return wfMessage( $msg )->numParams( $numEdits, $numUsers )->parse();
 928         }
 929
 930         /**
 931          * Get a header for a specified revision.
 932          *
 933          * @param $rev Revision
 934          * @param string $complete 'complete' to get the header wrapped depending
 935          *        the visibility of the revision and a link to edit the page.
 936          * @return String HTML fragment
 937          */
 938         protected function getRevisionHeader( Revision $rev, $complete = '' ) {
 939                 $lang = $this->getLanguage();
 940                 $user = $this->getUser();
 941                 $revtimestamp = $rev->getTimestamp();
 942                 $timestamp = $lang->userTimeAndDate( $revtimestamp, $user );
 943                 $dateofrev = $lang->userDate( $revtimestamp, $user );
 944                 $timeofrev = $lang->userTime( $revtimestamp, $user );
 945
 946                 $header = $this->msg(
 947                         $rev->isCurrent() ? 'currentrev-asof' : 'revisionasof',
 948                         $timestamp,
 949                         $dateofrev,
 950                         $timeofrev
 951                 )->escaped();
 952
 953                 if ( $complete !== 'complete' ) {
 954                         return $header;
 955                 }
 956
 957                 $title = $rev->getTitle();
 958
 959                 $header = Linker::linkKnown( $title, $header, array(),
 960                         array( 'oldid' => $rev->getID() ) );
 961
 962                 if ( $rev->userCan( Revision::DELETED_TEXT, $user ) ) {
 963                         $editQuery = array( 'action' => 'edit' );
 964                         if ( !$rev->isCurrent() ) {
 965                                 $editQuery['oldid'] = $rev->getID();
 966                         }
 967
 968                         $msg = $this->msg( $title->quickUserCan( 'edit', $user ) ? 'editold' : 'viewsourceold' )->escaped();
 969                         $header .= ' ' . $this->msg( 'parentheses' )->rawParams(
 970                                 Linker::linkKnown( $title, $msg, array(), $editQuery ) )->plain();
 971                         if ( $rev->isDeleted( Revision::DELETED_TEXT ) ) {
 972                                 $header = Html::rawElement( 'span', array( 'class' => 'history-deleted' ), $header );
 973                         }
 974                 } else {
 975                         $header = Html::rawElement( 'span', array( 'class' => 'history-deleted' ), $header );
 976                 }
 977
 978                 return $header;
 979         }
 980
 981         /**
 982          * Add the header to a diff body
 983          *
 984          * @return string
 985          */
 986         function addHeader( $diff, $otitle, $ntitle, $multi = '', $notice = '' ) {
 987                 // shared.css sets diff in interface language/dir, but the actual content
 988                 // is often in a different language, mostly the page content language/dir
 989                 $tableClass = 'diff diff-contentalign-' . htmlspecialchars( $this->getDiffLang()->alignStart() );
 990                 $header = "<table class='$tableClass'>";
 991
 992                 if ( !$diff && !$otitle ) {
 993                         $header .= "
 994                         <tr style='vertical-align: top;'>
 995                         <td class='diff-ntitle'>{$ntitle}</td>
 996                         </tr>";
 997                         $multiColspan = 1;
 998                 } else {
 999                         if ( $diff ) { // Safari/Chrome show broken output if cols not used
1000                                 $header .= "
1001                                 <col class='diff-marker' />
1002                                 <col class='diff-content' />
1003                                 <col class='diff-marker' />
1004                                 <col class='diff-content' />";
1005                                 $colspan = 2;
1006                                 $multiColspan = 4;
1007                         } else {
1008                                 $colspan = 1;
1009                                 $multiColspan = 2;
1010                         }
1011                         if ( $otitle || $ntitle ) {
1012                                 $header .= "
1013                                 <tr style='vertical-align: top;'>
1014                                 <td colspan='$colspan' class='diff-otitle'>{$otitle}</td>
1015                                 <td colspan='$colspan' class='diff-ntitle'>{$ntitle}</td>
1016                                 </tr>";
1017                         }
1018                 }
1019
1020                 if ( $multi != '' ) {
1021                         $header .= "<tr><td colspan='{$multiColspan}' style='text-align: center;' class='diff-multi'>{$multi}</td></tr>";
1022                 }
1023                 if ( $notice != '' ) {
1024                         $header .= "<tr><td colspan='{$multiColspan}' style='text-align: center;'>{$notice}</td></tr>";
1025                 }
1026
1027                 return $header . $diff . "</table>";
1028         }
1029
1030         /**
1031          * Use specified text instead of loading from the database
1032          * @deprecated since 1.21, use setContent() instead.
1033          */
1034         function setText( $oldText, $newText ) {
1035                 ContentHandler::deprecated( __METHOD__, "1.21" );
1036
1037                 $oldContent = ContentHandler::makeContent( $oldText, $this->getTitle() );
1038                 $newContent = ContentHandler::makeContent( $newText, $this->getTitle() );
1039
1040                 $this->setContent( $oldContent, $newContent );
1041         }
1042
1043         /**
1044          * Use specified text instead of loading from the database
1045          * @since 1.21
1046          */
1047         function setContent( Content $oldContent, Content $newContent ) {
1048                 $this->mOldContent = $oldContent;
1049                 $this->mNewContent = $newContent;
1050
1051                 $this->mTextLoaded = 2;
1052                 $this->mRevisionsLoaded = true;
1053         }
1054
1055         /**
1056          * Set the language in which the diff text is written
1057          * (Defaults to page content language).
1058          * @since 1.19
1059          */
1060         function setTextLanguage( $lang ) {
1061                 $this->mDiffLang = wfGetLangObj( $lang );
1062         }
1063
1064         /**
1065          * Load revision IDs
1066          */
1067         private function loadRevisionIds() {
1068                 if ( $this->mRevisionsIdsLoaded ) {
1069                         return;
1070                 }
1071
1072                 $this->mRevisionsIdsLoaded = true;
1073
1074                 $old = $this->mOldid;
1075                 $new = $this->mNewid;
1076
1077                 if ( $new === 'prev' ) {
1078                         # Show diff between revision $old and the previous one.
1079                         # Get previous one from DB.
1080                         $this->mNewid = intval( $old );
1081                         $this->mOldid = $this->getTitle()->getPreviousRevisionID( $this->mNewid );
1082                 } elseif ( $new === 'next' ) {
1083                         # Show diff between revision $old and the next one.
1084                         # Get next one from DB.
1085                         $this->mOldid = intval( $old );
1086                         $this->mNewid = $this->getTitle()->getNextRevisionID( $this->mOldid );
1087                         if ( $this->mNewid === false ) {
1088                                 # if no result, NewId points to the newest old revision. The only newer
1089                                 # revision is cur, which is "0".
1090                                 $this->mNewid = 0;
1091                         }
1092                 } else {
1093                         $this->mOldid = intval( $old );
1094                         $this->mNewid = intval( $new );
1095                         wfRunHooks( 'NewDifferenceEngine', array( $this->getTitle(), &$this->mOldid, &$this->mNewid, $old, $new ) );
1096                 }
1097         }
1098
1099         /**
1100          * Load revision metadata for the specified articles. If newid is 0, then compare
1101          * the old article in oldid to the current article; if oldid is 0, then
1102          * compare the current article to the immediately previous one (ignoring the
1103          * value of newid).
1104          *
1105          * If oldid is false, leave the corresponding revision object set
1106          * to false. This is impossible via ordinary user input, and is provided for
1107          * API convenience.
1108          *
1109          * @return bool
1110          */
1111         function loadRevisionData() {
1112                 if ( $this->mRevisionsLoaded ) {
1113                         return true;
1114                 }
1115
1116                 // Whether it succeeds or fails, we don't want to try again
1117                 $this->mRevisionsLoaded = true;
1118
1119                 $this->loadRevisionIds();
1120
1121                 // Load the new revision object
1122                 $this->mNewRev = $this->mNewid
1123                         ? Revision::newFromId( $this->mNewid )
1124                         : Revision::newFromTitle( $this->getTitle(), false, Revision::READ_NORMAL );
1125
1126                 if ( !$this->mNewRev instanceof Revision ) {
1127                         return false;
1128                 }
1129
1130                 // Update the new revision ID in case it was 0 (makes life easier doing UI stuff)
1131                 $this->mNewid = $this->mNewRev->getId();
1132                 $this->mNewPage = $this->mNewRev->getTitle();
1133
1134                 // Load the old revision object
1135                 $this->mOldRev = false;
1136                 if ( $this->mOldid ) {
1137                         $this->mOldRev = Revision::newFromId( $this->mOldid );
1138                 } elseif ( $this->mOldid === 0 ) {
1139                         $rev = $this->mNewRev->getPrevious();
1140                         if ( $rev ) {
1141                                 $this->mOldid = $rev->getId();
1142                                 $this->mOldRev = $rev;
1143                         } else {
1144                                 // No previous revision; mark to show as first-version only.
1145                                 $this->mOldid = false;
1146                                 $this->mOldRev = false;
1147                         }
1148                 } /* elseif ( $this->mOldid === false ) leave mOldRev false; */
1149
1150                 if ( is_null( $this->mOldRev ) ) {
1151                         return false;
1152                 }
1153
1154                 if ( $this->mOldRev ) {
1155                         $this->mOldPage = $this->mOldRev->getTitle();
1156                 }
1157
1158                 // Load tags information for both revisions
1159                 $dbr = wfGetDB( DB_SLAVE );
1160                 if ( $this->mOldid !== false ) {
1161                         $this->mOldTags = $dbr->selectField(
1162                                 'tag_summary',
1163                                 'ts_tags',
1164                                 array( 'ts_rev_id' => $this->mOldid ),
1165                                 __METHOD__
1166                         );
1167                 } else {
1168                         $this->mOldTags = false;
1169                 }
1170                 $this->mNewTags = $dbr->selectField(
1171                         'tag_summary',
1172                         'ts_tags',
1173                         array( 'ts_rev_id' => $this->mNewid ),
1174                         __METHOD__
1175                 );
1176
1177                 return true;
1178         }
1179
1180         /**
1181          * Load the text of the revisions, as well as revision data.
1182          *
1183          * @return bool
1184          */
1185         function loadText() {
1186                 if ( $this->mTextLoaded == 2 ) {
1187                         return true;
1188                 }
1189
1190                 // Whether it succeeds or fails, we don't want to try again
1191                 $this->mTextLoaded = 2;
1192
1193                 if ( !$this->loadRevisionData() ) {
1194                         return false;
1195                 }
1196
1197                 if ( $this->mOldRev ) {
1198                         $this->mOldContent = $this->mOldRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1199                         if ( $this->mOldContent === null ) {
1200                                 return false;
1201                         }
1202                 }
1203
1204                 if ( $this->mNewRev ) {
1205                         $this->mNewContent = $this->mNewRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1206                         if ( $this->mNewContent === null ) {
1207                                 return false;
1208                         }
1209                 }
1210
1211                 return true;
1212         }
1213
1214         /**
1215          * Load the text of the new revision, not the old one
1216          *
1217          * @return bool
1218          */
1219         function loadNewText() {
1220                 if ( $this->mTextLoaded >= 1 ) {
1221                         return true;
1222                 }
1223
1224                 $this->mTextLoaded = 1;
1225
1226                 if ( !$this->loadRevisionData() ) {
1227                         return false;
1228                 }
1229
1230                 $this->mNewContent = $this->mNewRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1231
1232                 return true;
1233         }
1234 }