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                                 if ( $multi !== '' ) {
 616                                         $multi .= '<br />';
 617                                 }
 618                                 $multi .= $this->msg( 'diff-empty' )->parse();
 619                         }
 620                         return $this->addHeader( $body, $otitle, $ntitle, $multi, $notice );
 621                 }
 622         }
 623
 624         /**
 625          * Get the diff table body, without header
 626          *
 627          * @return mixed (string/false)
 628          */
 629         public function getDiffBody() {
 630                 global $wgMemc;
 631                 wfProfileIn( __METHOD__ );
 632                 $this->mCacheHit = true;
 633                 // Check if the diff should be hidden from this user
 634                 if ( !$this->loadRevisionData() ) {
 635                         wfProfileOut( __METHOD__ );
 636                         return false;
 637                 } elseif ( $this->mOldRev && !$this->mOldRev->userCan( Revision::DELETED_TEXT, $this->getUser() ) ) {
 638                         wfProfileOut( __METHOD__ );
 639                         return false;
 640                 } elseif ( $this->mNewRev && !$this->mNewRev->userCan( Revision::DELETED_TEXT, $this->getUser() ) ) {
 641                         wfProfileOut( __METHOD__ );
 642                         return false;
 643                 }
 644                 // Short-circuit
 645                 // If mOldRev is false, it means that the
 646                 if ( $this->mOldRev === false || ( $this->mOldRev && $this->mNewRev
 647                         && $this->mOldRev->getID() == $this->mNewRev->getID() ) )
 648                 {
 649                         wfProfileOut( __METHOD__ );
 650                         return '';
 651                 }
 652                 // Cacheable?
 653                 $key = false;
 654                 if ( $this->mOldid && $this->mNewid ) {
 655                         $key = wfMemcKey( 'diff', 'version', MW_DIFF_VERSION,
 656                                 'oldid', $this->mOldid, 'newid', $this->mNewid );
 657                         // Try cache
 658                         if ( !$this->mRefreshCache ) {
 659                                 $difftext = $wgMemc->get( $key );
 660                                 if ( $difftext ) {
 661                                         wfIncrStats( 'diff_cache_hit' );
 662                                         $difftext = $this->localiseLineNumbers( $difftext );
 663                                         $difftext .= "\n<!-- diff cache key $key -->\n";
 664                                         wfProfileOut( __METHOD__ );
 665                                         return $difftext;
 666                                 }
 667                         } // don't try to load but save the result
 668                 }
 669                 $this->mCacheHit = false;
 670
 671                 // Loadtext is permission safe, this just clears out the diff
 672                 if ( !$this->loadText() ) {
 673                         wfProfileOut( __METHOD__ );
 674                         return false;
 675                 }
 676
 677                 $difftext = $this->generateContentDiffBody( $this->mOldContent, $this->mNewContent );
 678
 679                 // Save to cache for 7 days
 680                 if ( !wfRunHooks( 'AbortDiffCache', array( &$this ) ) ) {
 681                         wfIncrStats( 'diff_uncacheable' );
 682                 } elseif ( $key !== false && $difftext !== false ) {
 683                         wfIncrStats( 'diff_cache_miss' );
 684                         $wgMemc->set( $key, $difftext, 7 * 86400 );
 685                 } else {
 686                         wfIncrStats( 'diff_uncacheable' );
 687                 }
 688                 // Replace line numbers with the text in the user's language
 689                 if ( $difftext !== false ) {
 690                         $difftext = $this->localiseLineNumbers( $difftext );
 691                 }
 692                 wfProfileOut( __METHOD__ );
 693                 return $difftext;
 694         }
 695
 696         /**
 697          * Make sure the proper modules are loaded before we try to
 698          * make the diff
 699          */
 700         private function initDiffEngines() {
 701                 global $wgExternalDiffEngine;
 702                 if ( $wgExternalDiffEngine == 'wikidiff' && !function_exists( 'wikidiff_do_diff' ) ) {
 703                         wfProfileIn( __METHOD__ . '-php_wikidiff.so' );
 704                         wfDl( 'php_wikidiff' );
 705                         wfProfileOut( __METHOD__ . '-php_wikidiff.so' );
 706                 }
 707                 elseif ( $wgExternalDiffEngine == 'wikidiff2' && !function_exists( 'wikidiff2_do_diff' ) ) {
 708                         wfProfileIn( __METHOD__ . '-php_wikidiff2.so' );
 709                         wfDl( 'wikidiff2' );
 710                         wfProfileOut( __METHOD__ . '-php_wikidiff2.so' );
 711                 }
 712         }
 713
 714         /**
 715          * Generate a diff, no caching.
 716          *
 717          * This implementation uses generateTextDiffBody() to generate a diff based on the default
 718          * serialization of the given Content objects. This will fail if $old or $new are not
 719          * instances of TextContent.
 720          *
 721          * Subclasses may override this to provide a different rendering for the diff,
 722          * perhaps taking advantage of the content's native form. This is required for all content
 723          * models that are not text based.
 724          *
 725          * @param $old Content: old content
 726          * @param $new Content: new content
 727          *
 728          * @return bool|string
 729          * @since 1.21
 730          * @throws MWException if $old or $new are not instances of TextContent.
 731          */
 732         function generateContentDiffBody( Content $old, Content $new ) {
 733                 if ( !( $old instanceof TextContent ) ) {
 734                         throw new MWException( "Diff not implemented for " . get_class( $old ) . "; "
 735                                         . "override generateContentDiffBody to fix this." );
 736                 }
 737
 738                 if ( !( $new instanceof TextContent ) ) {
 739                         throw new MWException( "Diff not implemented for " . get_class( $new ) . "; "
 740                                 . "override generateContentDiffBody to fix this." );
 741                 }
 742
 743                 $otext = $old->serialize();
 744                 $ntext = $new->serialize();
 745
 746                 return $this->generateTextDiffBody( $otext, $ntext );
 747         }
 748
 749         /**
 750          * Generate a diff, no caching
 751          *
 752          * @param string $otext old text, must be already segmented
 753          * @param string $ntext new text, must be already segmented
 754          * @return bool|string
 755          * @deprecated since 1.21, use generateContentDiffBody() instead!
 756          */
 757         function generateDiffBody( $otext, $ntext ) {
 758                 ContentHandler::deprecated( __METHOD__, "1.21" );
 759
 760                 return $this->generateTextDiffBody( $otext, $ntext );
 761         }
 762
 763         /**
 764          * Generate a diff, no caching
 765          *
 766          * @todo move this to TextDifferenceEngine, make DifferenceEngine abstract. At some point.
 767          *
 768          * @param string $otext old text, must be already segmented
 769          * @param string $ntext new text, must be already segmented
 770          * @return bool|string
 771          */
 772         function generateTextDiffBody( $otext, $ntext ) {
 773                 global $wgExternalDiffEngine, $wgContLang;
 774
 775                 wfProfileIn( __METHOD__ );
 776
 777                 $otext = str_replace( "\r\n", "\n", $otext );
 778                 $ntext = str_replace( "\r\n", "\n", $ntext );
 779
 780                 $this->initDiffEngines();
 781
 782                 if ( $wgExternalDiffEngine == 'wikidiff' && function_exists( 'wikidiff_do_diff' ) ) {
 783                         # For historical reasons, external diff engine expects
 784                         # input text to be HTML-escaped already
 785                         $otext = htmlspecialchars ( $wgContLang->segmentForDiff( $otext ) );
 786                         $ntext = htmlspecialchars ( $wgContLang->segmentForDiff( $ntext ) );
 787                         wfProfileOut( __METHOD__ );
 788                         return $wgContLang->unsegmentForDiff( wikidiff_do_diff( $otext, $ntext, 2 ) ) .
 789                         $this->debug( 'wikidiff1' );
 790                 }
 791
 792                 if ( $wgExternalDiffEngine == 'wikidiff2' && function_exists( 'wikidiff2_do_diff' ) ) {
 793                         # Better external diff engine, the 2 may some day be dropped
 794                         # This one does the escaping and segmenting itself
 795                         wfProfileIn( 'wikidiff2_do_diff' );
 796                         $text = wikidiff2_do_diff( $otext, $ntext, 2 );
 797                         $text .= $this->debug( 'wikidiff2' );
 798                         wfProfileOut( 'wikidiff2_do_diff' );
 799                         wfProfileOut( __METHOD__ );
 800                         return $text;
 801                 }
 802                 if ( $wgExternalDiffEngine != 'wikidiff3' && $wgExternalDiffEngine !== false ) {
 803                         # Diff via the shell
 804                         $tmpDir = wfTempDir();
 805                         $tempName1 = tempnam( $tmpDir, 'diff_' );
 806                         $tempName2 = tempnam( $tmpDir, 'diff_' );
 807
 808                         $tempFile1 = fopen( $tempName1, "w" );
 809                         if ( !$tempFile1 ) {
 810                                 wfProfileOut( __METHOD__ );
 811                                 return false;
 812                         }
 813                         $tempFile2 = fopen( $tempName2, "w" );
 814                         if ( !$tempFile2 ) {
 815                                 wfProfileOut( __METHOD__ );
 816                                 return false;
 817                         }
 818                         fwrite( $tempFile1, $otext );
 819                         fwrite( $tempFile2, $ntext );
 820                         fclose( $tempFile1 );
 821                         fclose( $tempFile2 );
 822                         $cmd = wfEscapeShellArg( $wgExternalDiffEngine, $tempName1, $tempName2 );
 823                         wfProfileIn( __METHOD__ . "-shellexec" );
 824                         $difftext = wfShellExec( $cmd );
 825                         $difftext .= $this->debug( "external $wgExternalDiffEngine" );
 826                         wfProfileOut( __METHOD__ . "-shellexec" );
 827                         unlink( $tempName1 );
 828                         unlink( $tempName2 );
 829                         wfProfileOut( __METHOD__ );
 830                         return $difftext;
 831                 }
 832
 833                 # Native PHP diff
 834                 $ota = explode( "\n", $wgContLang->segmentForDiff( $otext ) );
 835                 $nta = explode( "\n", $wgContLang->segmentForDiff( $ntext ) );
 836                 $diffs = new Diff( $ota, $nta );
 837                 $formatter = new TableDiffFormatter();
 838                 $difftext = $wgContLang->unsegmentForDiff( $formatter->format( $diffs ) ) .
 839                 wfProfileOut( __METHOD__ );
 840                 return $difftext;
 841         }
 842
 843         /**
 844          * Generate a debug comment indicating diff generating time,
 845          * server node, and generator backend.
 846          * @return string
 847          */
 848         protected function debug( $generator = "internal" ) {
 849                 global $wgShowHostnames;
 850                 if ( !$this->enableDebugComment ) {
 851                         return '';
 852                 }
 853                 $data = array( $generator );
 854                 if ( $wgShowHostnames ) {
 855                         $data[] = wfHostname();
 856                 }
 857                 $data[] = wfTimestamp( TS_DB );
 858                 return "<!-- diff generator: " .
 859                 implode( " ",
 860                 array_map(
 861                                         "htmlspecialchars",
 862                 $data ) ) .
 863                         " -->\n";
 864         }
 865
 866         /**
 867          * Replace line numbers with the text in the user's language
 868          * @return mixed
 869          */
 870         function localiseLineNumbers( $text ) {
 871                 return preg_replace_callback( '/<!--LINE (\d+)-->/',
 872                 array( &$this, 'localiseLineNumbersCb' ), $text );
 873         }
 874
 875         function localiseLineNumbersCb( $matches ) {
 876                 if ( $matches[1] === '1' && $this->mReducedLineNumbers ) {
 877                         return '';
 878                 }
 879                 return $this->msg( 'lineno' )->numParams( $matches[1] )->escaped();
 880         }
 881
 882         /**
 883          * If there are revisions between the ones being compared, return a note saying so.
 884          * @return string
 885          */
 886         function getMultiNotice() {
 887                 if ( !is_object( $this->mOldRev ) || !is_object( $this->mNewRev ) ) {
 888                         return '';
 889                 } elseif ( !$this->mOldPage->equals( $this->mNewPage ) ) {
 890                         // Comparing two different pages? Count would be meaningless.
 891                         return '';
 892                 }
 893
 894                 if ( $this->mOldRev->getTimestamp() > $this->mNewRev->getTimestamp() ) {
 895                         $oldRev = $this->mNewRev; // flip
 896                         $newRev = $this->mOldRev; // flip
 897                 } else { // normal case
 898                         $oldRev = $this->mOldRev;
 899                         $newRev = $this->mNewRev;
 900                 }
 901
 902                 $nEdits = $this->mNewPage->countRevisionsBetween( $oldRev, $newRev );
 903                 if ( $nEdits > 0 ) {
 904                         $limit = 100; // use diff-multi-manyusers if too many users
 905                         $numUsers = $this->mNewPage->countAuthorsBetween( $oldRev, $newRev, $limit );
 906                         return self::intermediateEditsMsg( $nEdits, $numUsers, $limit );
 907                 }
 908                 return ''; // nothing
 909         }
 910
 911         /**
 912          * Get a notice about how many intermediate edits and users there are
 913          * @param $numEdits int
 914          * @param $numUsers int
 915          * @param $limit int
 916          * @return string
 917          */
 918         public static function intermediateEditsMsg( $numEdits, $numUsers, $limit ) {
 919                 if ( $numUsers > $limit ) {
 920                         $msg = 'diff-multi-manyusers';
 921                         $numUsers = $limit;
 922                 } else {
 923                         $msg = 'diff-multi';
 924                 }
 925                 return wfMessage( $msg )->numParams( $numEdits, $numUsers )->parse();
 926         }
 927
 928         /**
 929          * Get a header for a specified revision.
 930          *
 931          * @param $rev Revision
 932          * @param string $complete 'complete' to get the header wrapped depending
 933          *        the visibility of the revision and a link to edit the page.
 934          * @return String HTML fragment
 935          */
 936         protected function getRevisionHeader( Revision $rev, $complete = '' ) {
 937                 $lang = $this->getLanguage();
 938                 $user = $this->getUser();
 939                 $revtimestamp = $rev->getTimestamp();
 940                 $timestamp = $lang->userTimeAndDate( $revtimestamp, $user );
 941                 $dateofrev = $lang->userDate( $revtimestamp, $user );
 942                 $timeofrev = $lang->userTime( $revtimestamp, $user );
 943
 944                 $header = $this->msg(
 945                         $rev->isCurrent() ? 'currentrev-asof' : 'revisionasof',
 946                         $timestamp,
 947                         $dateofrev,
 948                         $timeofrev
 949                 )->escaped();
 950
 951                 if ( $complete !== 'complete' ) {
 952                         return $header;
 953                 }
 954
 955                 $title = $rev->getTitle();
 956
 957                 $header = Linker::linkKnown( $title, $header, array(),
 958                         array( 'oldid' => $rev->getID() ) );
 959
 960                 if ( $rev->userCan( Revision::DELETED_TEXT, $user ) ) {
 961                         $editQuery = array( 'action' => 'edit' );
 962                         if ( !$rev->isCurrent() ) {
 963                                 $editQuery['oldid'] = $rev->getID();
 964                         }
 965
 966                         $msg = $this->msg( $title->quickUserCan( 'edit', $user ) ? 'editold' : 'viewsourceold' )->escaped();
 967                         $header .= ' ' . $this->msg( 'parentheses' )->rawParams(
 968                                 Linker::linkKnown( $title, $msg, array(), $editQuery ) )->plain();
 969                         if ( $rev->isDeleted( Revision::DELETED_TEXT ) ) {
 970                                 $header = Html::rawElement( 'span', array( 'class' => 'history-deleted' ), $header );
 971                         }
 972                 } else {
 973                         $header = Html::rawElement( 'span', array( 'class' => 'history-deleted' ), $header );
 974                 }
 975
 976                 return $header;
 977         }
 978
 979         /**
 980          * Add the header to a diff body
 981          *
 982          * @return string
 983          */
 984         function addHeader( $diff, $otitle, $ntitle, $multi = '', $notice = '' ) {
 985                 // shared.css sets diff in interface language/dir, but the actual content
 986                 // is often in a different language, mostly the page content language/dir
 987                 $tableClass = 'diff diff-contentalign-' . htmlspecialchars( $this->getDiffLang()->alignStart() );
 988                 $header = "<table class='$tableClass'>";
 989
 990                 if ( !$diff && !$otitle ) {
 991                         $header .= "
 992                         <tr style='vertical-align: top;'>
 993                         <td class='diff-ntitle'>{$ntitle}</td>
 994                         </tr>";
 995                         $multiColspan = 1;
 996                 } else {
 997                         if ( $diff ) { // Safari/Chrome show broken output if cols not used
 998                                 $header .= "
 999                                 <col class='diff-marker' />
1000                                 <col class='diff-content' />
1001                                 <col class='diff-marker' />
1002                                 <col class='diff-content' />";
1003                                 $colspan = 2;
1004                                 $multiColspan = 4;
1005                         } else {
1006                                 $colspan = 1;
1007                                 $multiColspan = 2;
1008                         }
1009                         if ( $otitle || $ntitle ) {
1010                                 $header .= "
1011                                 <tr style='vertical-align: top;'>
1012                                 <td colspan='$colspan' class='diff-otitle'>{$otitle}</td>
1013                                 <td colspan='$colspan' class='diff-ntitle'>{$ntitle}</td>
1014                                 </tr>";
1015                         }
1016                 }
1017
1018                 if ( $multi != '' ) {
1019                         $header .= "<tr><td colspan='{$multiColspan}' style='text-align: center;' class='diff-multi'>{$multi}</td></tr>";
1020                 }
1021                 if ( $notice != '' ) {
1022                         $header .= "<tr><td colspan='{$multiColspan}' style='text-align: center;'>{$notice}</td></tr>";
1023                 }
1024
1025                 return $header . $diff . "</table>";
1026         }
1027
1028         /**
1029          * Use specified text instead of loading from the database
1030          * @deprecated since 1.21, use setContent() instead.
1031          */
1032         function setText( $oldText, $newText ) {
1033                 ContentHandler::deprecated( __METHOD__, "1.21" );
1034
1035                 $oldContent = ContentHandler::makeContent( $oldText, $this->getTitle() );
1036                 $newContent = ContentHandler::makeContent( $newText, $this->getTitle() );
1037
1038                 $this->setContent( $oldContent, $newContent );
1039         }
1040
1041         /**
1042          * Use specified text instead of loading from the database
1043          * @since 1.21
1044          */
1045         function setContent( Content $oldContent, Content $newContent ) {
1046                 $this->mOldContent = $oldContent;
1047                 $this->mNewContent = $newContent;
1048
1049                 $this->mTextLoaded = 2;
1050                 $this->mRevisionsLoaded = true;
1051         }
1052
1053         /**
1054          * Set the language in which the diff text is written
1055          * (Defaults to page content language).
1056          * @since 1.19
1057          */
1058         function setTextLanguage( $lang ) {
1059                 $this->mDiffLang = wfGetLangObj( $lang );
1060         }
1061
1062         /**
1063          * Load revision IDs
1064          */
1065         private function loadRevisionIds() {
1066                 if ( $this->mRevisionsIdsLoaded ) {
1067                         return;
1068                 }
1069
1070                 $this->mRevisionsIdsLoaded = true;
1071
1072                 $old = $this->mOldid;
1073                 $new = $this->mNewid;
1074
1075                 if ( $new === 'prev' ) {
1076                         # Show diff between revision $old and the previous one.
1077                         # Get previous one from DB.
1078                         $this->mNewid = intval( $old );
1079                         $this->mOldid = $this->getTitle()->getPreviousRevisionID( $this->mNewid );
1080                 } elseif ( $new === 'next' ) {
1081                         # Show diff between revision $old and the next one.
1082                         # Get next one from DB.
1083                         $this->mOldid = intval( $old );
1084                         $this->mNewid = $this->getTitle()->getNextRevisionID( $this->mOldid );
1085                         if ( $this->mNewid === false ) {
1086                                 # if no result, NewId points to the newest old revision. The only newer
1087                                 # revision is cur, which is "0".
1088                                 $this->mNewid = 0;
1089                         }
1090                 } else {
1091                         $this->mOldid = intval( $old );
1092                         $this->mNewid = intval( $new );
1093                         wfRunHooks( 'NewDifferenceEngine', array( $this->getTitle(), &$this->mOldid, &$this->mNewid, $old, $new ) );
1094                 }
1095         }
1096
1097         /**
1098          * Load revision metadata for the specified articles. If newid is 0, then compare
1099          * the old article in oldid to the current article; if oldid is 0, then
1100          * compare the current article to the immediately previous one (ignoring the
1101          * value of newid).
1102          *
1103          * If oldid is false, leave the corresponding revision object set
1104          * to false. This is impossible via ordinary user input, and is provided for
1105          * API convenience.
1106          *
1107          * @return bool
1108          */
1109         function loadRevisionData() {
1110                 if ( $this->mRevisionsLoaded ) {
1111                         return true;
1112                 }
1113
1114                 // Whether it succeeds or fails, we don't want to try again
1115                 $this->mRevisionsLoaded = true;
1116
1117                 $this->loadRevisionIds();
1118
1119                 // Load the new revision object
1120                 $this->mNewRev = $this->mNewid
1121                         ? Revision::newFromId( $this->mNewid )
1122                         : Revision::newFromTitle( $this->getTitle(), false, Revision::READ_NORMAL );
1123
1124                 if ( !$this->mNewRev instanceof Revision ) {
1125                         return false;
1126                 }
1127
1128                 // Update the new revision ID in case it was 0 (makes life easier doing UI stuff)
1129                 $this->mNewid = $this->mNewRev->getId();
1130                 $this->mNewPage = $this->mNewRev->getTitle();
1131
1132                 // Load the old revision object
1133                 $this->mOldRev = false;
1134                 if ( $this->mOldid ) {
1135                         $this->mOldRev = Revision::newFromId( $this->mOldid );
1136                 } elseif ( $this->mOldid === 0 ) {
1137                         $rev = $this->mNewRev->getPrevious();
1138                         if ( $rev ) {
1139                                 $this->mOldid = $rev->getId();
1140                                 $this->mOldRev = $rev;
1141                         } else {
1142                                 // No previous revision; mark to show as first-version only.
1143                                 $this->mOldid = false;
1144                                 $this->mOldRev = false;
1145                         }
1146                 } /* elseif ( $this->mOldid === false ) leave mOldRev false; */
1147
1148                 if ( is_null( $this->mOldRev ) ) {
1149                         return false;
1150                 }
1151
1152                 if ( $this->mOldRev ) {
1153                         $this->mOldPage = $this->mOldRev->getTitle();
1154                 }
1155
1156                 // Load tags information for both revisions
1157                 $dbr = wfGetDB( DB_SLAVE );
1158                 if ( $this->mOldid !== false ) {
1159                         $this->mOldTags = $dbr->selectField(
1160                                 'tag_summary',
1161                                 'ts_tags',
1162                                 array( 'ts_rev_id' => $this->mOldid ),
1163                                 __METHOD__
1164                         );
1165                 } else {
1166                         $this->mOldTags = false;
1167                 }
1168                 $this->mNewTags = $dbr->selectField(
1169                         'tag_summary',
1170                         'ts_tags',
1171                         array( 'ts_rev_id' => $this->mNewid ),
1172                         __METHOD__
1173                 );
1174
1175                 return true;
1176         }
1177
1178         /**
1179          * Load the text of the revisions, as well as revision data.
1180          *
1181          * @return bool
1182          */
1183         function loadText() {
1184                 if ( $this->mTextLoaded == 2 ) {
1185                         return true;
1186                 } else {
1187                         // Whether it succeeds or fails, we don't want to try again
1188                         $this->mTextLoaded = 2;
1189                 }
1190
1191                 if ( !$this->loadRevisionData() ) {
1192                         return false;
1193                 }
1194                 if ( $this->mOldRev ) {
1195                         $this->mOldContent = $this->mOldRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1196                         if ( $this->mOldContent === null ) {
1197                                 return false;
1198                         }
1199                 }
1200                 if ( $this->mNewRev ) {
1201                         $this->mNewContent = $this->mNewRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1202                         if ( $this->mNewContent === null ) {
1203                                 return false;
1204                         }
1205                 }
1206                 return true;
1207         }
1208
1209         /**
1210          * Load the text of the new revision, not the old one
1211          *
1212          * @return bool
1213          */
1214         function loadNewText() {
1215                 if ( $this->mTextLoaded >= 1 ) {
1216                         return true;
1217                 } else {
1218                         $this->mTextLoaded = 1;
1219                 }
1220                 if ( !$this->loadRevisionData() ) {
1221                         return false;
1222                 }
1223                 $this->mNewContent = $this->mNewRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1224                 return true;
1225         }
1226 }