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