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 $mOldContent, $mNewContent;
  42         protected $mDiffLang;
  43
  44         /**
  45          * @var Title
  46          */
  47         var $mOldPage, $mNewPage;
  48         var $mRcidMarkPatrolled;
  49
  50         /**
  51          * @var Revision
  52          */
  53         var $mOldRev, $mNewRev;
  54         private $mRevisionsIdsLoaded = false; // Have the revisions IDs been loaded
  55         var $mRevisionsLoaded = false; // Have the revisions been loaded
  56         var $mTextLoaded = 0; // How many text blobs have been loaded, 0, 1 or 2?
  57         var $mCacheHit = false; // Was the diff fetched from cache?
  58
  59         /**
  60          * Set this to true to add debug info to the HTML output.
  61          * Warning: this may cause RSS readers to spuriously mark articles as "new"
  62          * (bug 20601)
  63          */
  64         var $enableDebugComment = false;
  65
  66         // If true, line X is not displayed when X is 1, for example to increase
  67         // readability and conserve space with many small diffs.
  68         protected $mReducedLineNumbers = false;
  69
  70         // Link to action=markpatrolled
  71         protected $mMarkPatrolledLink = null;
  72
  73         protected $unhide = false; # show rev_deleted content if allowed
  74         /**#@-*/
  75
  76         /**
  77          * Constructor
  78          * @param $context IContextSource context to use, anything else will be ignored
  79          * @param $old Integer old ID we want to show and diff with.
  80          * @param $new String either 'prev' or 'next'.
  81          * @param $rcid Integer ??? FIXME (default 0)
  82          * @param $refreshCache boolean If set, refreshes the diff cache
  83          * @param $unhide boolean If set, allow viewing deleted revs
  84          */
  85         function __construct( $context = null, $old = 0, $new = 0, $rcid = 0,
  86                 $refreshCache = false, $unhide = false )
  87         {
  88                 if ( $context instanceof IContextSource ) {
  89                         $this->setContext( $context );
  90                 }
  91
  92                 wfDebug( "DifferenceEngine old '$old' new '$new' rcid '$rcid'\n" );
  93
  94                 $this->mOldid = $old;
  95                 $this->mNewid = $new;
  96                 $this->mRcidMarkPatrolled = intval( $rcid );  # force it to be an integer
  97                 $this->mRefreshCache = $refreshCache;
  98                 $this->unhide = $unhide;
  99         }
 100
 101         /**
 102          * @param $value bool
 103          */
 104         function setReducedLineNumbers( $value = true ) {
 105                 $this->mReducedLineNumbers = $value;
 106         }
 107
 108         /**
 109          * @return Language
 110          */
 111         function getDiffLang() {
 112                 if ( $this->mDiffLang === null ) {
 113                         # Default language in which the diff text is written.
 114                         $this->mDiffLang = $this->getTitle()->getPageLanguage();
 115                 }
 116                 return $this->mDiffLang;
 117         }
 118
 119         /**
 120          * @return bool
 121          */
 122         function wasCacheHit() {
 123                 return $this->mCacheHit;
 124         }
 125
 126         /**
 127          * @return int
 128          */
 129         function getOldid() {
 130                 $this->loadRevisionIds();
 131                 return $this->mOldid;
 132         }
 133
 134         /**
 135          * @return Bool|int
 136          */
 137         function getNewid() {
 138                 $this->loadRevisionIds();
 139                 return $this->mNewid;
 140         }
 141
 142         /**
 143          * Look up a special:Undelete link to the given deleted revision id,
 144          * as a workaround for being unable to load deleted diffs in currently.
 145          *
 146          * @param int $id revision ID
 147          * @return mixed URL or false
 148          */
 149         function deletedLink( $id ) {
 150                 if ( $this->getUser()->isAllowed( 'deletedhistory' ) ) {
 151                         $dbr = wfGetDB( DB_SLAVE );
 152                         $row = $dbr->selectRow('archive', '*',
 153                                 array( 'ar_rev_id' => $id ),
 154                                 __METHOD__ );
 155                         if ( $row ) {
 156                                 $rev = Revision::newFromArchiveRow( $row );
 157                                 $title = Title::makeTitleSafe( $row->ar_namespace, $row->ar_title );
 158                                 return SpecialPage::getTitleFor( 'Undelete' )->getFullURL( array(
 159                                         'target' => $title->getPrefixedText(),
 160                                         'timestamp' => $rev->getTimestamp()
 161                                 ));
 162                         }
 163                 }
 164                 return false;
 165         }
 166
 167         /**
 168          * Build a wikitext link toward a deleted revision, if viewable.
 169          *
 170          * @param int $id revision ID
 171          * @return string wikitext fragment
 172          */
 173         function deletedIdMarker( $id ) {
 174                 $link = $this->deletedLink( $id );
 175                 if ( $link ) {
 176                         return "[$link $id]";
 177                 } else {
 178                         return $id;
 179                 }
 180         }
 181
 182         private function showMissingRevision() {
 183                 $out = $this->getOutput();
 184
 185                 $missing = array();
 186                 if ( $this->mOldRev === null ) {
 187                         $missing[] = $this->deletedIdMarker( $this->mOldid );
 188                 }
 189                 if ( $this->mNewRev === null ) {
 190                         $missing[] = $this->deletedIdMarker( $this->mNewid );
 191                 }
 192
 193                 $out->setPageTitle( $this->msg( 'errorpagetitle' ) );
 194                 $out->addWikiMsg( 'difference-missing-revision',
 195                         $this->getLanguage()->listToText( $missing ), count( $missing ) );
 196         }
 197
 198         function showDiffPage( $diffOnly = false ) {
 199                 wfProfileIn( __METHOD__ );
 200
 201                 # Allow frames except in certain special cases
 202                 $out = $this->getOutput();
 203                 $out->allowClickjacking();
 204                 $out->setRobotPolicy( 'noindex,nofollow' );
 205
 206                 if ( !$this->loadRevisionData() ) {
 207                         $this->showMissingRevision();
 208                         wfProfileOut( __METHOD__ );
 209                         return;
 210                 }
 211
 212                 $user = $this->getUser();
 213                 $permErrors = $this->mNewPage->getUserPermissionsErrors( 'read', $user );
 214                 if ( $this->mOldPage ) { # mOldPage might not be set, see below.
 215                         $permErrors = wfMergeErrorArrays( $permErrors,
 216                                 $this->mOldPage->getUserPermissionsErrors( 'read', $user ) );
 217                 }
 218                 if ( count( $permErrors ) ) {
 219                         wfProfileOut( __METHOD__ );
 220                         throw new PermissionsError( 'read', $permErrors );
 221                 }
 222
 223                 # If external diffs are enabled both globally and for the user,
 224                 # we'll use the application/x-external-editor interface to call
 225                 # an external diff tool like kompare, kdiff3, etc.
 226                 if ( ExternalEdit::useExternalEngine( $this->getContext(), 'diff' ) ) { #FIXME: how to handle this for non-text content?
 227                         $urls = array(
 228                                 'File' => array( 'Extension' => 'wiki', 'URL' =>
 229                                         # This should be mOldPage, but it may not be set, see below.
 230                                         $this->mNewPage->getCanonicalURL( array(
 231                                                 'action' => 'raw', 'oldid' => $this->mOldid ) )
 232                                 ),
 233                                 'File2' => array( 'Extension' => 'wiki', 'URL' =>
 234                                         $this->mNewPage->getCanonicalURL( array(
 235                                                 'action' => 'raw', 'oldid' => $this->mNewid ) )
 236                                 ),
 237                         );
 238
 239                         $externalEditor = new ExternalEdit( $this->getContext(), $urls );
 240                         $externalEditor->execute();
 241
 242                         wfProfileOut( __METHOD__ );
 243                         return;
 244                 }
 245
 246                 $rollback = '';
 247                 $undoLink = '';
 248
 249                 $query = array();
 250                 # Carry over 'diffonly' param via navigation links
 251                 if ( $diffOnly != $user->getBoolOption( 'diffonly' ) ) {
 252                         $query['diffonly'] = $diffOnly;
 253                 }
 254                 # Cascade unhide param in links for easy deletion browsing
 255                 if ( $this->unhide ) {
 256                         $query['unhide'] = 1;
 257                 }
 258
 259                 # Check if one of the revisions is deleted/suppressed
 260                 $deleted = $suppressed = false;
 261                 $allowed = $this->mNewRev->userCan( Revision::DELETED_TEXT, $user );
 262
 263                 # mOldRev is false if the difference engine is called with a "vague" query for
 264                 # a diff between a version V and its previous version V' AND the version V
 265                 # is the first version of that article. In that case, V' does not exist.
 266                 if ( $this->mOldRev === false ) {
 267                         $out->setPageTitle( $this->msg( 'difference-title', $this->mNewPage->getPrefixedText() ) );
 268                         $samePage = true;
 269                         $oldHeader = '';
 270                 } else {
 271                         wfRunHooks( 'DiffViewHeader', array( $this, $this->mOldRev, $this->mNewRev ) );
 272
 273                         $sk = $this->getSkin();
 274                         if ( method_exists( $sk, 'suppressQuickbar' ) ) {
 275                                 $sk->suppressQuickbar();
 276                         }
 277
 278                         if ( $this->mNewPage->equals( $this->mOldPage ) ) {
 279                                 $out->setPageTitle( $this->msg( 'difference-title', $this->mNewPage->getPrefixedText() ) );
 280                                 $samePage = true;
 281                         } else {
 282                                 $out->setPageTitle( $this->msg( 'difference-title-multipage', $this->mOldPage->getPrefixedText(),
 283                                         $this->mNewPage->getPrefixedText() ) );
 284                                 $out->addSubtitle( $this->msg( 'difference-multipage' ) );
 285                                 $samePage = false;
 286                         }
 287
 288                         if ( $samePage && $this->mNewPage->quickUserCan( 'edit', $user ) ) {
 289                                 if ( $this->mNewRev->isCurrent() && $this->mNewPage->userCan( 'rollback', $user ) ) {
 290                                         $out->preventClickjacking();
 291                                         $rollback = '&#160;&#160;&#160;' . Linker::generateRollback( $this->mNewRev, $this->getContext() );
 292                                 }
 293                                 if ( !$this->mOldRev->isDeleted( Revision::DELETED_TEXT ) && !$this->mNewRev->isDeleted( Revision::DELETED_TEXT ) ) {
 294                                         $undoLink = ' ' . $this->msg( 'parentheses' )->rawParams(
 295                                                 Html::element( 'a', array(
 296                                                         'href' => $this->mNewPage->getLocalUrl( array(
 297                                                                 'action' => 'edit',
 298                                                                 'undoafter' => $this->mOldid,
 299                                                                 'undo' => $this->mNewid ) ),
 300                                                         'title' => Linker::titleAttrib( 'undo' )
 301                                                 ),
 302                                                 $this->msg( 'editundo' )->text()
 303                                         ) )->escaped();
 304                                 }
 305                         }
 306
 307                         # Make "previous revision link"
 308                         if ( $samePage && $this->mOldRev->getPrevious() ) {
 309                                 $prevlink = Linker::linkKnown(
 310                                         $this->mOldPage,
 311                                         $this->msg( 'previousdiff' )->escaped(),
 312                                         array( 'id' => 'differences-prevlink' ),
 313                                         array( 'diff' => 'prev', 'oldid' => $this->mOldid ) + $query
 314                                 );
 315                         } else {
 316                                 $prevlink = '&#160;';
 317                         }
 318
 319                         if ( $this->mOldRev->isMinor() ) {
 320                                 $oldminor = ChangesList::flag( 'minor' );
 321                         } else {
 322                                 $oldminor = '';
 323                         }
 324
 325                         $ldel = $this->revisionDeleteLink( $this->mOldRev );
 326                         $oldRevisionHeader = $this->getRevisionHeader( $this->mOldRev, 'complete' );
 327
 328                         $oldHeader = '<div id="mw-diff-otitle1"><strong>' . $oldRevisionHeader . '</strong></div>' .
 329                                 '<div id="mw-diff-otitle2">' .
 330                                         Linker::revUserTools( $this->mOldRev, !$this->unhide ) . '</div>' .
 331                                 '<div id="mw-diff-otitle3">' . $oldminor .
 332                                         Linker::revComment( $this->mOldRev, !$diffOnly, !$this->unhide ) . $ldel . '</div>' .
 333                                 '<div id="mw-diff-otitle4">' . $prevlink . '</div>';
 334
 335                         if ( $this->mOldRev->isDeleted( Revision::DELETED_TEXT ) ) {
 336                                 $deleted = true; // old revisions text is hidden
 337                                 if ( $this->mOldRev->isDeleted( Revision::DELETED_RESTRICTED ) ) {
 338                                         $suppressed = true; // also suppressed
 339                                 }
 340                         }
 341
 342                         # Check if this user can see the revisions
 343                         if ( !$this->mOldRev->userCan( Revision::DELETED_TEXT, $user ) ) {
 344                                 $allowed = false;
 345                         }
 346                 }
 347
 348                 # Make "next revision link"
 349                 # Skip next link on the top revision
 350                 if ( $samePage && !$this->mNewRev->isCurrent() ) {
 351                         $nextlink = Linker::linkKnown(
 352                                 $this->mNewPage,
 353                                 $this->msg( 'nextdiff' )->escaped(),
 354                                 array( 'id' => 'differences-nextlink' ),
 355                                 array( 'diff' => 'next', 'oldid' => $this->mNewid ) + $query
 356                         );
 357                 } else {
 358                         $nextlink = '&#160;';
 359                 }
 360
 361                 if ( $this->mNewRev->isMinor() ) {
 362                         $newminor = ChangesList::flag( 'minor' );
 363                 } else {
 364                         $newminor = '';
 365                 }
 366
 367                 # Handle RevisionDelete links...
 368                 $rdel = $this->revisionDeleteLink( $this->mNewRev );
 369                 $newRevisionHeader = $this->getRevisionHeader( $this->mNewRev, 'complete' ) . $undoLink;
 370
 371                 $newHeader = '<div id="mw-diff-ntitle1"><strong>' . $newRevisionHeader . '</strong></div>' .
 372                         '<div id="mw-diff-ntitle2">' . Linker::revUserTools( $this->mNewRev, !$this->unhide ) .
 373                                 " $rollback</div>" .
 374                         '<div id="mw-diff-ntitle3">' . $newminor .
 375                                 Linker::revComment( $this->mNewRev, !$diffOnly, !$this->unhide ) . $rdel . '</div>' .
 376                         '<div id="mw-diff-ntitle4">' . $nextlink . $this->markPatrolledLink() . '</div>';
 377
 378                 if ( $this->mNewRev->isDeleted( Revision::DELETED_TEXT ) ) {
 379                         $deleted = true; // new revisions text is hidden
 380                         if ( $this->mNewRev->isDeleted( Revision::DELETED_RESTRICTED ) )
 381                                 $suppressed = true; // also suppressed
 382                 }
 383
 384                 # If the diff cannot be shown due to a deleted revision, then output
 385                 # the diff header and links to unhide (if available)...
 386                 if ( $deleted && ( !$this->unhide || !$allowed ) ) {
 387                         $this->showDiffStyle();
 388                         $multi = $this->getMultiNotice();
 389                         $out->addHTML( $this->addHeader( '', $oldHeader, $newHeader, $multi ) );
 390                         if ( !$allowed ) {
 391                                 $msg = $suppressed ? 'rev-suppressed-no-diff' : 'rev-deleted-no-diff';
 392                                 # Give explanation for why revision is not visible
 393                                 $out->wrapWikiMsg( "<div id='mw-$msg' class='mw-warning plainlinks'>\n$1\n</div>\n",
 394                                         array( $msg ) );
 395                         } else {
 396                                 # Give explanation and add a link to view the diff...
 397                                 $link = $this->getTitle()->getFullUrl( $this->getRequest()->appendQueryValue( 'unhide', '1', true ) );
 398                                 $msg = $suppressed ? 'rev-suppressed-unhide-diff' : 'rev-deleted-unhide-diff';
 399                                 $out->wrapWikiMsg( "<div id='mw-$msg' class='mw-warning plainlinks'>\n$1\n</div>\n", array( $msg, $link ) );
 400                         }
 401                 # Otherwise, output a regular diff...
 402                 } else {
 403                         # Add deletion notice if the user is viewing deleted content
 404                         $notice = '';
 405                         if ( $deleted ) {
 406                                 $msg = $suppressed ? 'rev-suppressed-diff-view' : 'rev-deleted-diff-view';
 407                                 $notice = "<div id='mw-$msg' class='mw-warning plainlinks'>\n" . $this->msg( $msg )->parse() . "</div>\n";
 408                         }
 409                         $this->showDiff( $oldHeader, $newHeader, $notice );
 410                         if ( !$diffOnly ) {
 411                                 $this->renderNewRevision();
 412                         }
 413                 }
 414                 wfProfileOut( __METHOD__ );
 415         }
 416
 417         /**
 418          * Get a link to mark the change as patrolled, or '' if there's either no
 419          * revision to patrol or the user is not allowed to to it.
 420          * Side effect: this method will call OutputPage::preventClickjacking()
 421          * when a link is builded.
 422          *
 423          * @return String
 424          */
 425         protected function markPatrolledLink() {
 426                 global $wgUseRCPatrol;
 427
 428                 if ( $this->mMarkPatrolledLink === null ) {
 429                         // Prepare a change patrol link, if applicable
 430                         if ( $wgUseRCPatrol && $this->mNewPage->quickUserCan( 'patrol', $this->getUser() ) ) {
 431                                 // If we've been given an explicit change identifier, use it; saves time
 432                                 if ( $this->mRcidMarkPatrolled ) {
 433                                         $rcid = $this->mRcidMarkPatrolled;
 434                                         $rc = RecentChange::newFromId( $rcid );
 435                                         // Already patrolled?
 436                                         $rcid = is_object( $rc ) && !$rc->getAttribute( 'rc_patrolled' ) ? $rcid : 0;
 437                                 } else {
 438                                         // Look for an unpatrolled change corresponding to this diff
 439                                         $db = wfGetDB( DB_SLAVE );
 440                                         $change = RecentChange::newFromConds(
 441                                                 array(
 442                                                 // Redundant user,timestamp condition so we can use the existing index
 443                                                         'rc_user_text'  => $this->mNewRev->getRawUserText(),
 444                                                         'rc_timestamp'  => $db->timestamp( $this->mNewRev->getTimestamp() ),
 445                                                         'rc_this_oldid' => $this->mNewid,
 446                                                         'rc_last_oldid' => $this->mOldid,
 447                                                         'rc_patrolled'  => 0
 448                                                 ),
 449                                                 __METHOD__
 450                                         );
 451                                         if ( $change instanceof RecentChange ) {
 452                                                 $rcid = $change->mAttribs['rc_id'];
 453                                                 $this->mRcidMarkPatrolled = $rcid;
 454                                         } else {
 455                                                 // None found
 456                                                 $rcid = 0;
 457                                         }
 458                                 }
 459                                 // Build the link
 460                                 if ( $rcid ) {
 461                                         $this->getOutput()->preventClickjacking();
 462                                         $token = $this->getUser()->getEditToken( $rcid );
 463                                         $this->mMarkPatrolledLink = ' <span class="patrollink">[' . Linker::linkKnown(
 464                                                 $this->mNewPage,
 465                                                 $this->msg( 'markaspatrolleddiff' )->escaped(),
 466                                                 array(),
 467                                                 array(
 468                                                         'action' => 'markpatrolled',
 469                                                         'rcid' => $rcid,
 470                                                         'token' => $token,
 471                                                 )
 472                                         ) . ']</span>';
 473                                 } else {
 474                                         $this->mMarkPatrolledLink = '';
 475                                 }
 476                         } else {
 477                                 $this->mMarkPatrolledLink = '';
 478                         }
 479                 }
 480
 481                 return $this->mMarkPatrolledLink;
 482         }
 483
 484         /**
 485          * @param $rev Revision
 486          * @return String
 487          */
 488         protected function revisionDeleteLink( $rev ) {
 489                 $link = Linker::getRevDeleteLink( $this->getUser(), $rev, $rev->getTitle() );
 490                 if ( $link !== '' ) {
 491                         $link = '&#160;&#160;&#160;' . $link . ' ';
 492                 }
 493                 return $link;
 494         }
 495
 496         /**
 497          * Show the new revision of the page.
 498          */
 499         function renderNewRevision() {
 500                 wfProfileIn( __METHOD__ );
 501                 $out = $this->getOutput();
 502                 $revHeader = $this->getRevisionHeader( $this->mNewRev );
 503                 # Add "current version as of X" title
 504                 $out->addHTML( "<hr class='diff-hr' />
 505                 <h2 class='diff-currentversion-title'>{$revHeader}</h2>\n" );
 506                 # Page content may be handled by a hooked call instead...
 507                 if ( wfRunHooks( 'ArticleContentOnDiff', array( $this, $out ) ) ) {
 508                         $this->loadNewText();
 509                         $out->setRevisionId( $this->mNewid );
 510                         $out->setRevisionTimestamp( $this->mNewRev->getTimestamp() );
 511                         $out->setArticleFlag( true );
 512
 513                         #NOTE: only needed for B/C: custom rendering of JS/CSS via hook
 514                         if ( $this->mNewPage->isCssJsSubpage() || $this->mNewPage->isCssOrJsPage() ) {
 515                                 // Stolen from Article::view --AG 2007-10-11
 516                                 // Give hooks a chance to customise the output
 517                                 // @TODO: standardize this crap into one function
 518                                 if ( !Hook::isRegistered( 'ShowRawCssJs' )
 519                                         || wfRunHooks( 'ShowRawCssJs', array( ContentHandler::getContentText( $this->mNewContent ), $this->mNewPage, $out ) ) ) {
 520                                         // NOTE: deprecated hook, B/C only
 521                                         // use the content object's own rendering
 522                                         $po = $this->mContentObject->getParserOutput();
 523                                         $out->addHTML( $po->getText() );
 524                                 }
 525                         } elseif( !wfRunHooks( 'ArticleContentViewCustom', array( $this->mNewContent, $this->mNewPage, $out ) ) ) {
 526                                 // Handled by extension
 527                         } elseif( Hooks::isRegistered( 'ArticleViewCustom' )
 528                                         && !wfRunHooks( 'ArticleViewCustom', array( ContentHandler::getContentText( $this->mNewContent ), $this->mNewPage, $out ) ) ) {
 529                                 // NOTE: deprecated hook, B/C only
 530                                 // Handled by extension
 531                         } else {
 532                                 // Normal page
 533                                 if ( $this->getTitle()->equals( $this->mNewPage ) ) {
 534                                         // If the Title stored in the context is the same as the one
 535                                         // of the new revision, we can use its associated WikiPage
 536                                         // object.
 537                                         $wikiPage = $this->getWikiPage();
 538                                 } else {
 539                                         // Otherwise we need to create our own WikiPage object
 540                                         $wikiPage = WikiPage::factory( $this->mNewPage );
 541                                 }
 542
 543                                 $parserOutput = $this->getParserOutput( $wikiPage, $this->mNewRev );
 544
 545                                 # WikiPage::getParserOutput() should not return false, but just in case
 546                                 if( $parserOutput ) {
 547                                         $out->addParserOutput( $parserOutput );
 548                                 }
 549                         }
 550                 }
 551                 # Add redundant patrol link on bottom...
 552                 $out->addHTML( $this->markPatrolledLink() );
 553
 554                 wfProfileOut( __METHOD__ );
 555         }
 556
 557         protected function getParserOutput( WikiPage $page, Revision $rev ) {
 558                 $parserOptions = ParserOptions::newFromContext( $this->getContext() );
 559                 $parserOptions->enableLimitReport();
 560                 $parserOptions->setTidy( true );
 561
 562                 if ( !$rev->isCurrent() || !$rev->getTitle()->quickUserCan( "edit" ) ) {
 563                         $parserOptions->setEditSection( false );
 564                 }
 565
 566                 $parserOutput = $page->getParserOutput( $parserOptions, $rev->getId() );
 567                 return $parserOutput;
 568         }
 569
 570         /**
 571          * Get the diff text, send it to the OutputPage object
 572          * Returns false if the diff could not be generated, otherwise returns true
 573          *
 574          * @return bool
 575          */
 576         function showDiff( $otitle, $ntitle, $notice = '' ) {
 577                 $diff = $this->getDiff( $otitle, $ntitle, $notice );
 578                 if ( $diff === false ) {
 579                         $this->showMissingRevision();
 580                         return false;
 581                 } else {
 582                         $this->showDiffStyle();
 583                         $this->getOutput()->addHTML( $diff );
 584                         return true;
 585                 }
 586         }
 587
 588         /**
 589          * Add style sheets and supporting JS for diff display.
 590          */
 591         function showDiffStyle() {
 592                 $this->getOutput()->addModuleStyles( 'mediawiki.action.history.diff' );
 593         }
 594
 595         /**
 596          * Get complete diff table, including header
 597          *
 598          * @param $otitle Title: old title
 599          * @param $ntitle Title: new title
 600          * @param $notice String: HTML between diff header and body
 601          * @return mixed
 602          */
 603         function getDiff( $otitle, $ntitle, $notice = '' ) {
 604                 $body = $this->getDiffBody();
 605                 if ( $body === false ) {
 606                         return false;
 607                 } else {
 608                         $multi = $this->getMultiNotice();
 609                         return $this->addHeader( $body, $otitle, $ntitle, $multi, $notice );
 610                 }
 611         }
 612
 613         /**
 614          * Get the diff table body, without header
 615          *
 616          * @return mixed (string/false)
 617          */
 618         public function getDiffBody() {
 619                 global $wgMemc;
 620                 wfProfileIn( __METHOD__ );
 621                 $this->mCacheHit = true;
 622                 // Check if the diff should be hidden from this user
 623                 if ( !$this->loadRevisionData() ) {
 624                         wfProfileOut( __METHOD__ );
 625                         return false;
 626                 } elseif ( $this->mOldRev && !$this->mOldRev->userCan( Revision::DELETED_TEXT, $this->getUser() ) ) {
 627                         wfProfileOut( __METHOD__ );
 628                         return false;
 629                 } elseif ( $this->mNewRev && !$this->mNewRev->userCan( Revision::DELETED_TEXT, $this->getUser() ) ) {
 630                         wfProfileOut( __METHOD__ );
 631                         return false;
 632                 }
 633                 // Short-circuit
 634                 // If mOldRev is false, it means that the
 635                 if ( $this->mOldRev === false || ( $this->mOldRev && $this->mNewRev
 636                         && $this->mOldRev->getID() == $this->mNewRev->getID() ) )
 637                 {
 638                         wfProfileOut( __METHOD__ );
 639                         return '';
 640                 }
 641                 // Cacheable?
 642                 $key = false;
 643                 if ( $this->mOldid && $this->mNewid ) {
 644                         $key = wfMemcKey( 'diff', 'version', MW_DIFF_VERSION,
 645                                 'oldid', $this->mOldid, 'newid', $this->mNewid );
 646                         // Try cache
 647                         if ( !$this->mRefreshCache ) {
 648                                 $difftext = $wgMemc->get( $key );
 649                                 if ( $difftext ) {
 650                                         wfIncrStats( 'diff_cache_hit' );
 651                                         $difftext = $this->localiseLineNumbers( $difftext );
 652                                         $difftext .= "\n<!-- diff cache key $key -->\n";
 653                                         wfProfileOut( __METHOD__ );
 654                                         return $difftext;
 655                                 }
 656                         } // don't try to load but save the result
 657                 }
 658                 $this->mCacheHit = false;
 659
 660                 // Loadtext is permission safe, this just clears out the diff
 661                 if ( !$this->loadText() ) {
 662                         wfProfileOut( __METHOD__ );
 663                         return false;
 664                 }
 665
 666                 $difftext = $this->generateContentDiffBody( $this->mOldContent, $this->mNewContent );
 667
 668                 // Save to cache for 7 days
 669                 if ( !wfRunHooks( 'AbortDiffCache', array( &$this ) ) ) {
 670                         wfIncrStats( 'diff_uncacheable' );
 671                 } elseif ( $key !== false && $difftext !== false ) {
 672                         wfIncrStats( 'diff_cache_miss' );
 673                         $wgMemc->set( $key, $difftext, 7 * 86400 );
 674                 } else {
 675                         wfIncrStats( 'diff_uncacheable' );
 676                 }
 677                 // Replace line numbers with the text in the user's language
 678                 if ( $difftext !== false ) {
 679                         $difftext = $this->localiseLineNumbers( $difftext );
 680                 }
 681                 wfProfileOut( __METHOD__ );
 682                 return $difftext;
 683         }
 684
 685         /**
 686          * Make sure the proper modules are loaded before we try to
 687          * make the diff
 688          */
 689         private function initDiffEngines() {
 690                 global $wgExternalDiffEngine;
 691                 if ( $wgExternalDiffEngine == 'wikidiff' && !function_exists( 'wikidiff_do_diff' ) ) {
 692                         wfProfileIn( __METHOD__ . '-php_wikidiff.so' );
 693                         wfDl( 'php_wikidiff' );
 694                         wfProfileOut( __METHOD__ . '-php_wikidiff.so' );
 695                 }
 696                 elseif ( $wgExternalDiffEngine == 'wikidiff2' && !function_exists( 'wikidiff2_do_diff' ) ) {
 697                         wfProfileIn( __METHOD__ . '-php_wikidiff2.so' );
 698                         wfDl( 'wikidiff2' );
 699                         wfProfileOut( __METHOD__ . '-php_wikidiff2.so' );
 700                 }
 701         }
 702
 703         /**
 704          * Generate a diff, no caching.
 705          *
 706          * Subclasses may override this to provide a
 707          *
 708          * @param $old Content: old content
 709          * @param $new Content: new content
 710          *
 711          * @since 1.WD
 712          */
 713         function generateContentDiffBody( Content $old, Content $new ) {
 714                 #XXX: generate a warning if $old or $new are not instances of TextContent?
 715                 #XXX: fail if $old and $new don't have the same content model? or what?
 716
 717                 $otext = $old->serialize();
 718                 $ntext = $new->serialize();
 719
 720                 #XXX: text should be "already segmented". what does that mean?
 721                 return $this->generateTextDiffBody( $otext, $ntext );
 722         }
 723
 724         /**
 725          * Generate a diff, no caching
 726          *
 727          * @param $otext String: old text, must be already segmented
 728          * @param $ntext String: new text, must be already segmented
 729          * @deprecated since 1.WD, use generateContentDiffBody() instead!
 730          */
 731         function generateDiffBody( $otext, $ntext ) {
 732                 wfDeprecated( __METHOD__, "1.WD" );
 733
 734                 return $this->generateTextDiffBody( $otext, $ntext );
 735         }
 736
 737         /**
 738          * Generate a diff, no caching
 739          *
 740          * @todo move this to TextDifferenceEngine, make DifferenceEngine abstract. At some point.
 741          *
 742          * @param $otext String: old text, must be already segmented
 743          * @param $ntext String: new text, must be already segmented
 744          * @return bool|string
 745          */
 746         function generateTextDiffBody( $otext, $ntext ) {
 747                 global $wgExternalDiffEngine, $wgContLang;
 748
 749                 wfProfileIn( __METHOD__ );
 750
 751                 $otext = str_replace( "\r\n", "\n", $otext );
 752                 $ntext = str_replace( "\r\n", "\n", $ntext );
 753
 754                 $this->initDiffEngines();
 755
 756                 if ( $wgExternalDiffEngine == 'wikidiff' && function_exists( 'wikidiff_do_diff' ) ) {
 757                         # For historical reasons, external diff engine expects
 758                         # input text to be HTML-escaped already
 759                         $otext = htmlspecialchars ( $wgContLang->segmentForDiff( $otext ) );
 760                         $ntext = htmlspecialchars ( $wgContLang->segmentForDiff( $ntext ) );
 761                         wfProfileOut( __METHOD__ );
 762                         return $wgContLang->unsegmentForDiff( wikidiff_do_diff( $otext, $ntext, 2 ) ) .
 763                         $this->debug( 'wikidiff1' );
 764                 }
 765
 766                 if ( $wgExternalDiffEngine == 'wikidiff2' && function_exists( 'wikidiff2_do_diff' ) ) {
 767                         # Better external diff engine, the 2 may some day be dropped
 768                         # This one does the escaping and segmenting itself
 769                         wfProfileIn( 'wikidiff2_do_diff' );
 770                         $text = wikidiff2_do_diff( $otext, $ntext, 2 );
 771                         $text .= $this->debug( 'wikidiff2' );
 772                         wfProfileOut( 'wikidiff2_do_diff' );
 773                         wfProfileOut( __METHOD__ );
 774                         return $text;
 775                 }
 776                 if ( $wgExternalDiffEngine != 'wikidiff3' && $wgExternalDiffEngine !== false ) {
 777                         # Diff via the shell
 778                         $tmpDir = wfTempDir();
 779                         $tempName1 = tempnam( $tmpDir, 'diff_' );
 780                         $tempName2 = tempnam( $tmpDir, 'diff_' );
 781
 782                         $tempFile1 = fopen( $tempName1, "w" );
 783                         if ( !$tempFile1 ) {
 784                                 wfProfileOut( __METHOD__ );
 785                                 return false;
 786                         }
 787                         $tempFile2 = fopen( $tempName2, "w" );
 788                         if ( !$tempFile2 ) {
 789                                 wfProfileOut( __METHOD__ );
 790                                 return false;
 791                         }
 792                         fwrite( $tempFile1, $otext );
 793                         fwrite( $tempFile2, $ntext );
 794                         fclose( $tempFile1 );
 795                         fclose( $tempFile2 );
 796                         $cmd = wfEscapeShellArg( $wgExternalDiffEngine, $tempName1, $tempName2 );
 797                         wfProfileIn( __METHOD__ . "-shellexec" );
 798                         $difftext = wfShellExec( $cmd );
 799                         $difftext .= $this->debug( "external $wgExternalDiffEngine" );
 800                         wfProfileOut( __METHOD__ . "-shellexec" );
 801                         unlink( $tempName1 );
 802                         unlink( $tempName2 );
 803                         wfProfileOut( __METHOD__ );
 804                         return $difftext;
 805                 }
 806
 807                 # Native PHP diff
 808                 $ota = explode( "\n", $wgContLang->segmentForDiff( $otext ) );
 809                 $nta = explode( "\n", $wgContLang->segmentForDiff( $ntext ) );
 810                 $diffs = new Diff( $ota, $nta );
 811                 $formatter = new TableDiffFormatter();
 812                 $difftext = $wgContLang->unsegmentForDiff( $formatter->format( $diffs ) ) .
 813                 wfProfileOut( __METHOD__ );
 814                 return $difftext;
 815         }
 816
 817         /**
 818          * Generate a debug comment indicating diff generating time,
 819          * server node, and generator backend.
 820          * @return string
 821          */
 822         protected function debug( $generator = "internal" ) {
 823                 global $wgShowHostnames;
 824                 if ( !$this->enableDebugComment ) {
 825                         return '';
 826                 }
 827                 $data = array( $generator );
 828                 if ( $wgShowHostnames ) {
 829                         $data[] = wfHostname();
 830                 }
 831                 $data[] = wfTimestamp( TS_DB );
 832                 return "<!-- diff generator: " .
 833                 implode( " ",
 834                 array_map(
 835                                         "htmlspecialchars",
 836                 $data ) ) .
 837                         " -->\n";
 838         }
 839
 840         /**
 841          * Replace line numbers with the text in the user's language
 842          * @return mixed
 843          */
 844         function localiseLineNumbers( $text ) {
 845                 return preg_replace_callback( '/<!--LINE (\d+)-->/',
 846                 array( &$this, 'localiseLineNumbersCb' ), $text );
 847         }
 848
 849         function localiseLineNumbersCb( $matches ) {
 850                 if ( $matches[1] === '1' && $this->mReducedLineNumbers ) return '';
 851                 return $this->msg( 'lineno' )->numParams( $matches[1] )->escaped();
 852         }
 853
 854
 855         /**
 856          * If there are revisions between the ones being compared, return a note saying so.
 857          * @return string
 858          */
 859         function getMultiNotice() {
 860                 if ( !is_object( $this->mOldRev ) || !is_object( $this->mNewRev ) ) {
 861                         return '';
 862                 } elseif ( !$this->mOldPage->equals( $this->mNewPage ) ) {
 863                         // Comparing two different pages? Count would be meaningless.
 864                         return '';
 865                 }
 866
 867                 if ( $this->mOldRev->getTimestamp() > $this->mNewRev->getTimestamp() ) {
 868                         $oldRev = $this->mNewRev; // flip
 869                         $newRev = $this->mOldRev; // flip
 870                 } else { // normal case
 871                         $oldRev = $this->mOldRev;
 872                         $newRev = $this->mNewRev;
 873                 }
 874
 875                 $nEdits = $this->mNewPage->countRevisionsBetween( $oldRev, $newRev );
 876                 if ( $nEdits > 0 ) {
 877                         $limit = 100; // use diff-multi-manyusers if too many users
 878                         $numUsers = $this->mNewPage->countAuthorsBetween( $oldRev, $newRev, $limit );
 879                         return self::intermediateEditsMsg( $nEdits, $numUsers, $limit );
 880                 }
 881                 return ''; // nothing
 882         }
 883
 884         /**
 885          * Get a notice about how many intermediate edits and users there are
 886          * @param $numEdits int
 887          * @param $numUsers int
 888          * @param $limit int
 889          * @return string
 890          */
 891         public static function intermediateEditsMsg( $numEdits, $numUsers, $limit ) {
 892                 if ( $numUsers > $limit ) {
 893                         $msg = 'diff-multi-manyusers';
 894                         $numUsers = $limit;
 895                 } else {
 896                         $msg = 'diff-multi';
 897                 }
 898                 return wfMessage( $msg )->numParams( $numEdits, $numUsers )->parse();
 899         }
 900
 901         /**
 902          * Get a header for a specified revision.
 903          *
 904          * @param $rev Revision
 905          * @param $complete String: 'complete' to get the header wrapped depending
 906          *        the visibility of the revision and a link to edit the page.
 907          * @return String HTML fragment
 908          */
 909         protected function getRevisionHeader( Revision $rev, $complete = '' ) {
 910                 $lang = $this->getLanguage();
 911                 $user = $this->getUser();
 912                 $revtimestamp = $rev->getTimestamp();
 913                 $timestamp = $lang->userTimeAndDate( $revtimestamp, $user );
 914                 $dateofrev = $lang->userDate( $revtimestamp, $user );
 915                 $timeofrev = $lang->userTime( $revtimestamp, $user );
 916
 917                 $header = $this->msg(
 918                         $rev->isCurrent() ? 'currentrev-asof' : 'revisionasof',
 919                         $timestamp,
 920                         $dateofrev,
 921                         $timeofrev
 922                 )->escaped();
 923
 924                 if ( $complete !== 'complete' ) {
 925                         return $header;
 926                 }
 927
 928                 $title = $rev->getTitle();
 929
 930                 $header = Linker::linkKnown( $title, $header, array(),
 931                         array( 'oldid' => $rev->getID() ) );
 932
 933                 if ( $rev->userCan( Revision::DELETED_TEXT, $user ) ) {
 934                         $editQuery = array( 'action' => 'edit' );
 935                         if ( !$rev->isCurrent() ) {
 936                                 $editQuery['oldid'] = $rev->getID();
 937                         }
 938
 939                         $msg = $this->msg( $title->quickUserCan( 'edit', $user ) ? 'editold' : 'viewsourceold' )->escaped();
 940                         $header .= ' ' . $this->msg( 'parentheses' )->rawParams(
 941                                 Linker::linkKnown( $title, $msg, array(), $editQuery ) )->plain();
 942                         if ( $rev->isDeleted( Revision::DELETED_TEXT ) ) {
 943                                 $header = Html::rawElement( 'span', array( 'class' => 'history-deleted' ), $header );
 944                         }
 945                 } else {
 946                         $header = Html::rawElement( 'span', array( 'class' => 'history-deleted' ), $header );
 947                 }
 948
 949                 return $header;
 950         }
 951
 952         /**
 953          * Add the header to a diff body
 954          *
 955          * @return string
 956          */
 957         function addHeader( $diff, $otitle, $ntitle, $multi = '', $notice = '' ) {
 958                 // shared.css sets diff in interface language/dir, but the actual content
 959                 // is often in a different language, mostly the page content language/dir
 960                 $tableClass = 'diff diff-contentalign-' . htmlspecialchars( $this->getDiffLang()->alignStart() );
 961                 $header = "<table class='$tableClass'>";
 962
 963                 if ( !$diff && !$otitle ) {
 964                         $header .= "
 965                         <tr valign='top'>
 966                         <td class='diff-ntitle'>{$ntitle}</td>
 967                         </tr>";
 968                         $multiColspan = 1;
 969                 } else {
 970                         if ( $diff ) { // Safari/Chrome show broken output if cols not used
 971                                 $header .= "
 972                                 <col class='diff-marker' />
 973                                 <col class='diff-content' />
 974                                 <col class='diff-marker' />
 975                                 <col class='diff-content' />";
 976                                 $colspan = 2;
 977                                 $multiColspan = 4;
 978                         } else {
 979                                 $colspan = 1;
 980                                 $multiColspan = 2;
 981                         }
 982                         $header .= "
 983                         <tr valign='top'>
 984                         <td colspan='$colspan' class='diff-otitle'>{$otitle}</td>
 985                         <td colspan='$colspan' class='diff-ntitle'>{$ntitle}</td>
 986                         </tr>";
 987                 }
 988
 989                 if ( $multi != '' ) {
 990                         $header .= "<tr><td colspan='{$multiColspan}' align='center' class='diff-multi'>{$multi}</td></tr>";
 991                 }
 992                 if ( $notice != '' ) {
 993                         $header .= "<tr><td colspan='{$multiColspan}' align='center'>{$notice}</td></tr>";
 994                 }
 995
 996                 return $header . $diff . "</table>";
 997         }
 998
 999         /**
1000          * Use specified text instead of loading from the database
1001          * @deprecated since 1.WD
1002          */
1003         function setText( $oldText, $newText ) { #FIXME: no longer use this, use setContent()!
1004                 wfDeprecated( __METHOD__, "1.WD" );
1005
1006                 $oldContent = ContentHandler::makeContent( $oldText, $this->getTitle() );
1007                 $newContent = ContentHandler::makeContent( $newText, $this->getTitle() );
1008
1009                 $this->setContent( $oldContent, $newContent );
1010         }
1011
1012         /**
1013          * Use specified text instead of loading from the database
1014          * @since 1.WD
1015          */
1016         function setContent( Content $oldContent, Content $newContent ) {
1017                 $this->mOldContent = $oldContent;
1018                 $this->mNewContent = $newContent;
1019
1020                 $this->mTextLoaded = 2;
1021                 $this->mRevisionsLoaded = true;
1022         }
1023
1024         /**
1025          * Set the language in which the diff text is written
1026          * (Defaults to page content language).
1027          * @since 1.19
1028          */
1029         function setTextLanguage( $lang ) {
1030                 $this->mDiffLang = wfGetLangObj( $lang );
1031         }
1032
1033         /**
1034          * Load revision IDs
1035          */
1036         private function loadRevisionIds() {
1037                 if ( $this->mRevisionsIdsLoaded ) {
1038                         return;
1039                 }
1040
1041                 $this->mRevisionsIdsLoaded = true;
1042
1043                 $old = $this->mOldid;
1044                 $new = $this->mNewid;
1045
1046                 if ( $new === 'prev' ) {
1047                         # Show diff between revision $old and the previous one.
1048                         # Get previous one from DB.
1049                         $this->mNewid = intval( $old );
1050                         $this->mOldid = $this->getTitle()->getPreviousRevisionID( $this->mNewid );
1051                 } elseif ( $new === 'next' ) {
1052                         # Show diff between revision $old and the next one.
1053                         # Get next one from DB.
1054                         $this->mOldid = intval( $old );
1055                         $this->mNewid = $this->getTitle()->getNextRevisionID( $this->mOldid );
1056                         if ( $this->mNewid === false ) {
1057                                 # if no result, NewId points to the newest old revision. The only newer
1058                                 # revision is cur, which is "0".
1059                                 $this->mNewid = 0;
1060                         }
1061                 } else {
1062                         $this->mOldid = intval( $old );
1063                         $this->mNewid = intval( $new );
1064                         wfRunHooks( 'NewDifferenceEngine', array( $this->getTitle(), &$this->mOldid, &$this->mNewid, $old, $new ) );
1065                 }
1066         }
1067
1068         /**
1069          * Load revision metadata for the specified articles. If newid is 0, then compare
1070          * the old article in oldid to the current article; if oldid is 0, then
1071          * compare the current article to the immediately previous one (ignoring the
1072          * value of newid).
1073          *
1074          * If oldid is false, leave the corresponding revision object set
1075          * to false. This is impossible via ordinary user input, and is provided for
1076          * API convenience.
1077          *
1078          * @return bool
1079          */
1080         function loadRevisionData() {
1081                 if ( $this->mRevisionsLoaded ) {
1082                         return true;
1083                 }
1084
1085                 // Whether it succeeds or fails, we don't want to try again
1086                 $this->mRevisionsLoaded = true;
1087
1088                 $this->loadRevisionIds();
1089
1090                 // Load the new revision object
1091                 $this->mNewRev = $this->mNewid
1092                         ? Revision::newFromId( $this->mNewid )
1093                         : Revision::newFromTitle( $this->getTitle(), false, Revision::READ_NORMAL );
1094
1095                 if ( !$this->mNewRev instanceof Revision ) {
1096                         return false;
1097                 }
1098
1099                 // Update the new revision ID in case it was 0 (makes life easier doing UI stuff)
1100                 $this->mNewid = $this->mNewRev->getId();
1101                 $this->mNewPage = $this->mNewRev->getTitle();
1102
1103                 // Load the old revision object
1104                 $this->mOldRev = false;
1105                 if ( $this->mOldid ) {
1106                         $this->mOldRev = Revision::newFromId( $this->mOldid );
1107                 } elseif ( $this->mOldid === 0 ) {
1108                         $rev = $this->mNewRev->getPrevious();
1109                         if ( $rev ) {
1110                                 $this->mOldid = $rev->getId();
1111                                 $this->mOldRev = $rev;
1112                         } else {
1113                                 // No previous revision; mark to show as first-version only.
1114                                 $this->mOldid = false;
1115                                 $this->mOldRev = false;
1116                         }
1117                 } /* elseif ( $this->mOldid === false ) leave mOldRev false; */
1118
1119                 if ( is_null( $this->mOldRev ) ) {
1120                         return false;
1121                 }
1122
1123                 if ( $this->mOldRev ) {
1124                         $this->mOldPage = $this->mOldRev->getTitle();
1125                 }
1126
1127                 return true;
1128         }
1129
1130         /**
1131          * Load the text of the revisions, as well as revision data.
1132          *
1133          * @return bool
1134          */
1135         function loadText() {
1136                 if ( $this->mTextLoaded == 2 ) {
1137                         return true;
1138                 } else {
1139                         // Whether it succeeds or fails, we don't want to try again
1140                         $this->mTextLoaded = 2;
1141                 }
1142
1143                 if ( !$this->loadRevisionData() ) {
1144                         return false;
1145                 }
1146                 if ( $this->mOldRev ) {
1147                         $this->mOldContent = $this->mOldRev->getContent( Revision::FOR_THIS_USER );
1148                         if ( $this->mOldContent === false ) {
1149                                 return false;
1150                         }
1151                 }
1152                 if ( $this->mNewRev ) {
1153                         $this->mNewContent = $this->mNewRev->getContent( Revision::FOR_THIS_USER );
1154                         if ( $this->mNewContent === false ) {
1155                                 return false;
1156                         }
1157                 }
1158                 return true;
1159         }
1160
1161         /**
1162          * Load the text of the new revision, not the old one
1163          *
1164          * @return bool
1165          */
1166         function loadNewText() {
1167                 if ( $this->mTextLoaded >= 1 ) {
1168                         return true;
1169                 } else {
1170                         $this->mTextLoaded = 1;
1171                 }
1172                 if ( !$this->loadRevisionData() ) {
1173                         return false;
1174                 }
1175                 $this->mNewContent = $this->mNewRev->getContent( Revision::FOR_THIS_USER );
1176                 return true;
1177         }
1178 }