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' ) ) {
 227                         //TODO: come up with a good solution for non-text content here.
 228                         //      at least, the content format needs to be passed to the client somehow.
 229                         //      Currently, action=raw will just fail for non-text content.
 230
 231                         $urls = array(
 232                                 'File' => array( 'Extension' => 'wiki', 'URL' =>
 233                                         # This should be mOldPage, but it may not be set, see below.
 234                                         $this->mNewPage->getCanonicalURL( array(
 235                                                 'action' => 'raw', 'oldid' => $this->mOldid ) )
 236                                 ),
 237                                 'File2' => array( 'Extension' => 'wiki', 'URL' =>
 238                                         $this->mNewPage->getCanonicalURL( array(
 239                                                 'action' => 'raw', 'oldid' => $this->mNewid ) )
 240                                 ),
 241                         );
 242
 243                         $externalEditor = new ExternalEdit( $this->getContext(), $urls );
 244                         $externalEditor->execute();
 245
 246                         wfProfileOut( __METHOD__ );
 247                         return;
 248                 }
 249
 250                 $rollback = '';
 251                 $undoLink = '';
 252
 253                 $query = array();
 254                 # Carry over 'diffonly' param via navigation links
 255                 if ( $diffOnly != $user->getBoolOption( 'diffonly' ) ) {
 256                         $query['diffonly'] = $diffOnly;
 257                 }
 258                 # Cascade unhide param in links for easy deletion browsing
 259                 if ( $this->unhide ) {
 260                         $query['unhide'] = 1;
 261                 }
 262
 263                 # Check if one of the revisions is deleted/suppressed
 264                 $deleted = $suppressed = false;
 265                 $allowed = $this->mNewRev->userCan( Revision::DELETED_TEXT, $user );
 266
 267                 # mOldRev is false if the difference engine is called with a "vague" query for
 268                 # a diff between a version V and its previous version V' AND the version V
 269                 # is the first version of that article. In that case, V' does not exist.
 270                 if ( $this->mOldRev === false ) {
 271                         $out->setPageTitle( $this->msg( 'difference-title', $this->mNewPage->getPrefixedText() ) );
 272                         $samePage = true;
 273                         $oldHeader = '';
 274                 } else {
 275                         wfRunHooks( 'DiffViewHeader', array( $this, $this->mOldRev, $this->mNewRev ) );
 276
 277                         $sk = $this->getSkin();
 278                         if ( method_exists( $sk, 'suppressQuickbar' ) ) {
 279                                 $sk->suppressQuickbar();
 280                         }
 281
 282                         if ( $this->mNewPage->equals( $this->mOldPage ) ) {
 283                                 $out->setPageTitle( $this->msg( 'difference-title', $this->mNewPage->getPrefixedText() ) );
 284                                 $samePage = true;
 285                         } else {
 286                                 $out->setPageTitle( $this->msg( 'difference-title-multipage', $this->mOldPage->getPrefixedText(),
 287                                         $this->mNewPage->getPrefixedText() ) );
 288                                 $out->addSubtitle( $this->msg( 'difference-multipage' ) );
 289                                 $samePage = false;
 290                         }
 291
 292                         if ( $samePage && $this->mNewPage->quickUserCan( 'edit', $user ) ) {
 293                                 if ( $this->mNewRev->isCurrent() && $this->mNewPage->userCan( 'rollback', $user ) ) {
 294                                         $out->preventClickjacking();
 295                                         $rollback = '&#160;&#160;&#160;' . Linker::generateRollback( $this->mNewRev, $this->getContext() );
 296                                 }
 297                                 if ( !$this->mOldRev->isDeleted( Revision::DELETED_TEXT ) && !$this->mNewRev->isDeleted( Revision::DELETED_TEXT ) ) {
 298                                         $undoLink = ' ' . $this->msg( 'parentheses' )->rawParams(
 299                                                 Html::element( 'a', array(
 300                                                         'href' => $this->mNewPage->getLocalUrl( array(
 301                                                                 'action' => 'edit',
 302                                                                 'undoafter' => $this->mOldid,
 303                                                                 'undo' => $this->mNewid ) ),
 304                                                         'title' => Linker::titleAttrib( 'undo' )
 305                                                 ),
 306                                                 $this->msg( 'editundo' )->text()
 307                                         ) )->escaped();
 308                                 }
 309                         }
 310
 311                         # Make "previous revision link"
 312                         if ( $samePage && $this->mOldRev->getPrevious() ) {
 313                                 $prevlink = Linker::linkKnown(
 314                                         $this->mOldPage,
 315                                         $this->msg( 'previousdiff' )->escaped(),
 316                                         array( 'id' => 'differences-prevlink' ),
 317                                         array( 'diff' => 'prev', 'oldid' => $this->mOldid ) + $query
 318                                 );
 319                         } else {
 320                                 $prevlink = '&#160;';
 321                         }
 322
 323                         if ( $this->mOldRev->isMinor() ) {
 324                                 $oldminor = ChangesList::flag( 'minor' );
 325                         } else {
 326                                 $oldminor = '';
 327                         }
 328
 329                         $ldel = $this->revisionDeleteLink( $this->mOldRev );
 330                         $oldRevisionHeader = $this->getRevisionHeader( $this->mOldRev, 'complete' );
 331
 332                         $oldHeader = '<div id="mw-diff-otitle1"><strong>' . $oldRevisionHeader . '</strong></div>' .
 333                                 '<div id="mw-diff-otitle2">' .
 334                                         Linker::revUserTools( $this->mOldRev, !$this->unhide ) . '</div>' .
 335                                 '<div id="mw-diff-otitle3">' . $oldminor .
 336                                         Linker::revComment( $this->mOldRev, !$diffOnly, !$this->unhide ) . $ldel . '</div>' .
 337                                 '<div id="mw-diff-otitle4">' . $prevlink . '</div>';
 338
 339                         if ( $this->mOldRev->isDeleted( Revision::DELETED_TEXT ) ) {
 340                                 $deleted = true; // old revisions text is hidden
 341                                 if ( $this->mOldRev->isDeleted( Revision::DELETED_RESTRICTED ) ) {
 342                                         $suppressed = true; // also suppressed
 343                                 }
 344                         }
 345
 346                         # Check if this user can see the revisions
 347                         if ( !$this->mOldRev->userCan( Revision::DELETED_TEXT, $user ) ) {
 348                                 $allowed = false;
 349                         }
 350                 }
 351
 352                 # Make "next revision link"
 353                 # Skip next link on the top revision
 354                 if ( $samePage && !$this->mNewRev->isCurrent() ) {
 355                         $nextlink = Linker::linkKnown(
 356                                 $this->mNewPage,
 357                                 $this->msg( 'nextdiff' )->escaped(),
 358                                 array( 'id' => 'differences-nextlink' ),
 359                                 array( 'diff' => 'next', 'oldid' => $this->mNewid ) + $query
 360                         );
 361                 } else {
 362                         $nextlink = '&#160;';
 363                 }
 364
 365                 if ( $this->mNewRev->isMinor() ) {
 366                         $newminor = ChangesList::flag( 'minor' );
 367                 } else {
 368                         $newminor = '';
 369                 }
 370
 371                 # Handle RevisionDelete links...
 372                 $rdel = $this->revisionDeleteLink( $this->mNewRev );
 373                 $newRevisionHeader = $this->getRevisionHeader( $this->mNewRev, 'complete' ) . $undoLink;
 374
 375                 $newHeader = '<div id="mw-diff-ntitle1"><strong>' . $newRevisionHeader . '</strong></div>' .
 376                         '<div id="mw-diff-ntitle2">' . Linker::revUserTools( $this->mNewRev, !$this->unhide ) .
 377                                 " $rollback</div>" .
 378                         '<div id="mw-diff-ntitle3">' . $newminor .
 379                                 Linker::revComment( $this->mNewRev, !$diffOnly, !$this->unhide ) . $rdel . '</div>' .
 380                         '<div id="mw-diff-ntitle4">' . $nextlink . $this->markPatrolledLink() . '</div>';
 381
 382                 if ( $this->mNewRev->isDeleted( Revision::DELETED_TEXT ) ) {
 383                         $deleted = true; // new revisions text is hidden
 384                         if ( $this->mNewRev->isDeleted( Revision::DELETED_RESTRICTED ) )
 385                                 $suppressed = true; // also suppressed
 386                 }
 387
 388                 # If the diff cannot be shown due to a deleted revision, then output
 389                 # the diff header and links to unhide (if available)...
 390                 if ( $deleted && ( !$this->unhide || !$allowed ) ) {
 391                         $this->showDiffStyle();
 392                         $multi = $this->getMultiNotice();
 393                         $out->addHTML( $this->addHeader( '', $oldHeader, $newHeader, $multi ) );
 394                         if ( !$allowed ) {
 395                                 $msg = $suppressed ? 'rev-suppressed-no-diff' : 'rev-deleted-no-diff';
 396                                 # Give explanation for why revision is not visible
 397                                 $out->wrapWikiMsg( "<div id='mw-$msg' class='mw-warning plainlinks'>\n$1\n</div>\n",
 398                                         array( $msg ) );
 399                         } else {
 400                                 # Give explanation and add a link to view the diff...
 401                                 $link = $this->getTitle()->getFullUrl( $this->getRequest()->appendQueryValue( 'unhide', '1', true ) );
 402                                 $msg = $suppressed ? 'rev-suppressed-unhide-diff' : 'rev-deleted-unhide-diff';
 403                                 $out->wrapWikiMsg( "<div id='mw-$msg' class='mw-warning plainlinks'>\n$1\n</div>\n", array( $msg, $link ) );
 404                         }
 405                 # Otherwise, output a regular diff...
 406                 } else {
 407                         # Add deletion notice if the user is viewing deleted content
 408                         $notice = '';
 409                         if ( $deleted ) {
 410                                 $msg = $suppressed ? 'rev-suppressed-diff-view' : 'rev-deleted-diff-view';
 411                                 $notice = "<div id='mw-$msg' class='mw-warning plainlinks'>\n" . $this->msg( $msg )->parse() . "</div>\n";
 412                         }
 413                         $this->showDiff( $oldHeader, $newHeader, $notice );
 414                         if ( !$diffOnly ) {
 415                                 $this->renderNewRevision();
 416                         }
 417                 }
 418                 wfProfileOut( __METHOD__ );
 419         }
 420
 421         /**
 422          * Get a link to mark the change as patrolled, or '' if there's either no
 423          * revision to patrol or the user is not allowed to to it.
 424          * Side effect: this method will call OutputPage::preventClickjacking()
 425          * when a link is builded.
 426          *
 427          * @return String
 428          */
 429         protected function markPatrolledLink() {
 430                 global $wgUseRCPatrol;
 431
 432                 if ( $this->mMarkPatrolledLink === null ) {
 433                         // Prepare a change patrol link, if applicable
 434                         if ( $wgUseRCPatrol && $this->mNewPage->quickUserCan( 'patrol', $this->getUser() ) ) {
 435                                 // If we've been given an explicit change identifier, use it; saves time
 436                                 if ( $this->mRcidMarkPatrolled ) {
 437                                         $rcid = $this->mRcidMarkPatrolled;
 438                                         $rc = RecentChange::newFromId( $rcid );
 439                                         // Already patrolled?
 440                                         $rcid = is_object( $rc ) && !$rc->getAttribute( 'rc_patrolled' ) ? $rcid : 0;
 441                                 } else {
 442                                         // Look for an unpatrolled change corresponding to this diff
 443                                         $db = wfGetDB( DB_SLAVE );
 444                                         $change = RecentChange::newFromConds(
 445                                                 array(
 446                                                 // Redundant user,timestamp condition so we can use the existing index
 447                                                         'rc_user_text'  => $this->mNewRev->getRawUserText(),
 448                                                         'rc_timestamp'  => $db->timestamp( $this->mNewRev->getTimestamp() ),
 449                                                         'rc_this_oldid' => $this->mNewid,
 450                                                         'rc_last_oldid' => $this->mOldid,
 451                                                         'rc_patrolled'  => 0
 452                                                 ),
 453                                                 __METHOD__
 454                                         );
 455                                         if ( $change instanceof RecentChange ) {
 456                                                 $rcid = $change->mAttribs['rc_id'];
 457                                                 $this->mRcidMarkPatrolled = $rcid;
 458                                         } else {
 459                                                 // None found
 460                                                 $rcid = 0;
 461                                         }
 462                                 }
 463                                 // Build the link
 464                                 if ( $rcid ) {
 465                                         $this->getOutput()->preventClickjacking();
 466                                         $token = $this->getUser()->getEditToken( $rcid );
 467                                         $this->mMarkPatrolledLink = ' <span class="patrollink">[' . Linker::linkKnown(
 468                                                 $this->mNewPage,
 469                                                 $this->msg( 'markaspatrolleddiff' )->escaped(),
 470                                                 array(),
 471                                                 array(
 472                                                         'action' => 'markpatrolled',
 473                                                         'rcid' => $rcid,
 474                                                         'token' => $token,
 475                                                 )
 476                                         ) . ']</span>';
 477                                 } else {
 478                                         $this->mMarkPatrolledLink = '';
 479                                 }
 480                         } else {
 481                                 $this->mMarkPatrolledLink = '';
 482                         }
 483                 }
 484
 485                 return $this->mMarkPatrolledLink;
 486         }
 487
 488         /**
 489          * @param $rev Revision
 490          * @return String
 491          */
 492         protected function revisionDeleteLink( $rev ) {
 493                 $link = Linker::getRevDeleteLink( $this->getUser(), $rev, $rev->getTitle() );
 494                 if ( $link !== '' ) {
 495                         $link = '&#160;&#160;&#160;' . $link . ' ';
 496                 }
 497                 return $link;
 498         }
 499
 500         /**
 501          * Show the new revision of the page.
 502          */
 503         function renderNewRevision() {
 504                 wfProfileIn( __METHOD__ );
 505                 $out = $this->getOutput();
 506                 $revHeader = $this->getRevisionHeader( $this->mNewRev );
 507                 # Add "current version as of X" title
 508                 $out->addHTML( "<hr class='diff-hr' />
 509                 <h2 class='diff-currentversion-title'>{$revHeader}</h2>\n" );
 510                 # Page content may be handled by a hooked call instead...
 511                 if ( wfRunHooks( 'ArticleContentOnDiff', array( $this, $out ) ) ) {
 512                         $this->loadNewText();
 513                         $out->setRevisionId( $this->mNewid );
 514                         $out->setRevisionTimestamp( $this->mNewRev->getTimestamp() );
 515                         $out->setArticleFlag( true );
 516
 517                         // NOTE: only needed for B/C: custom rendering of JS/CSS via hook
 518                         if ( $this->mNewPage->isCssJsSubpage() || $this->mNewPage->isCssOrJsPage() ) {
 519                                 // Stolen from Article::view --AG 2007-10-11
 520                                 // Give hooks a chance to customise the output
 521                                 // @TODO: standardize this crap into one function
 522                                 if ( ContentHandler::runLegacyHooks( 'ShowRawCssJs', array( $this->mNewContent, $this->mNewPage, $out ) ) ) {
 523                                         // NOTE: deprecated hook, B/C only
 524                                         // use the content object's own rendering
 525                                         $po = $this->mNewRev->getContent()->getParserOutput( $this->mNewRev->getTitle(), $this->mNewRev->getId() );
 526                                         $out->addHTML( $po->getText() );
 527                                 }
 528                         } elseif( !wfRunHooks( 'ArticleContentViewCustom', array( $this->mNewContent, $this->mNewPage, $out ) ) ) {
 529                                 // Handled by extension
 530                         } elseif( !ContentHandler::runLegacyHooks( 'ArticleViewCustom', array( $this->mNewContent, $this->mNewPage, $out ) ) ) {
 531                                 // NOTE: deprecated hook, B/C only
 532                                 // Handled by extension
 533                         } else {
 534                                 // Normal page
 535                                 if ( $this->getTitle()->equals( $this->mNewPage ) ) {
 536                                         // If the Title stored in the context is the same as the one
 537                                         // of the new revision, we can use its associated WikiPage
 538                                         // object.
 539                                         $wikiPage = $this->getWikiPage();
 540                                 } else {
 541                                         // Otherwise we need to create our own WikiPage object
 542                                         $wikiPage = WikiPage::factory( $this->mNewPage );
 543                                 }
 544
 545                                 $parserOutput = $this->getParserOutput( $wikiPage, $this->mNewRev );
 546
 547                                 # WikiPage::getParserOutput() should not return false, but just in case
 548                                 if( $parserOutput ) {
 549                                         $out->addParserOutput( $parserOutput );
 550                                 }
 551                         }
 552                 }
 553                 # Add redundant patrol link on bottom...
 554                 $out->addHTML( $this->markPatrolledLink() );
 555
 556                 wfProfileOut( __METHOD__ );
 557         }
 558
 559         protected function getParserOutput( WikiPage $page, Revision $rev ) {
 560                 $parserOptions = $page->makeParserOptions( $this->getContext() );
 561
 562                 if ( !$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 1.21
 712          */
 713         function generateContentDiffBody( Content $old, Content $new ) {
 714                 if ( !( $old instanceof TextContent ) ) {
 715                         throw new MWException( "Diff not implemented for " . get_class( $old ) . "; "
 716                                                                 . "override generateContentDiffBody to fix this." );
 717                 }
 718
 719                 if ( !( $new instanceof TextContent ) ) {
 720                         throw new MWException( "Diff not implemented for " . get_class( $new ) . "; "
 721                                 . "override generateContentDiffBody to fix this." );
 722                 }
 723
 724                 $otext = $old->serialize();
 725                 $ntext = $new->serialize();
 726
 727                 return $this->generateTextDiffBody( $otext, $ntext );
 728         }
 729
 730         /**
 731          * Generate a diff, no caching
 732          *
 733          * @param $otext String: old text, must be already segmented
 734          * @param $ntext String: new text, must be already segmented
 735          * @deprecated since 1.21, use generateContentDiffBody() instead!
 736          */
 737         function generateDiffBody( $otext, $ntext ) {
 738                 wfDeprecated( __METHOD__, "1.21" );
 739
 740                 return $this->generateTextDiffBody( $otext, $ntext );
 741         }
 742
 743         /**
 744          * Generate a diff, no caching
 745          *
 746          * @todo move this to TextDifferenceEngine, make DifferenceEngine abstract. At some point.
 747          *
 748          * @param $otext String: old text, must be already segmented
 749          * @param $ntext String: new text, must be already segmented
 750          * @return bool|string
 751          */
 752         function generateTextDiffBody( $otext, $ntext ) {
 753                 global $wgExternalDiffEngine, $wgContLang;
 754
 755                 wfProfileIn( __METHOD__ );
 756
 757                 $otext = str_replace( "\r\n", "\n", $otext );
 758                 $ntext = str_replace( "\r\n", "\n", $ntext );
 759
 760                 $this->initDiffEngines();
 761
 762                 if ( $wgExternalDiffEngine == 'wikidiff' && function_exists( 'wikidiff_do_diff' ) ) {
 763                         # For historical reasons, external diff engine expects
 764                         # input text to be HTML-escaped already
 765                         $otext = htmlspecialchars ( $wgContLang->segmentForDiff( $otext ) );
 766                         $ntext = htmlspecialchars ( $wgContLang->segmentForDiff( $ntext ) );
 767                         wfProfileOut( __METHOD__ );
 768                         return $wgContLang->unsegmentForDiff( wikidiff_do_diff( $otext, $ntext, 2 ) ) .
 769                         $this->debug( 'wikidiff1' );
 770                 }
 771
 772                 if ( $wgExternalDiffEngine == 'wikidiff2' && function_exists( 'wikidiff2_do_diff' ) ) {
 773                         # Better external diff engine, the 2 may some day be dropped
 774                         # This one does the escaping and segmenting itself
 775                         wfProfileIn( 'wikidiff2_do_diff' );
 776                         $text = wikidiff2_do_diff( $otext, $ntext, 2 );
 777                         $text .= $this->debug( 'wikidiff2' );
 778                         wfProfileOut( 'wikidiff2_do_diff' );
 779                         wfProfileOut( __METHOD__ );
 780                         return $text;
 781                 }
 782                 if ( $wgExternalDiffEngine != 'wikidiff3' && $wgExternalDiffEngine !== false ) {
 783                         # Diff via the shell
 784                         $tmpDir = wfTempDir();
 785                         $tempName1 = tempnam( $tmpDir, 'diff_' );
 786                         $tempName2 = tempnam( $tmpDir, 'diff_' );
 787
 788                         $tempFile1 = fopen( $tempName1, "w" );
 789                         if ( !$tempFile1 ) {
 790                                 wfProfileOut( __METHOD__ );
 791                                 return false;
 792                         }
 793                         $tempFile2 = fopen( $tempName2, "w" );
 794                         if ( !$tempFile2 ) {
 795                                 wfProfileOut( __METHOD__ );
 796                                 return false;
 797                         }
 798                         fwrite( $tempFile1, $otext );
 799                         fwrite( $tempFile2, $ntext );
 800                         fclose( $tempFile1 );
 801                         fclose( $tempFile2 );
 802                         $cmd = wfEscapeShellArg( $wgExternalDiffEngine, $tempName1, $tempName2 );
 803                         wfProfileIn( __METHOD__ . "-shellexec" );
 804                         $difftext = wfShellExec( $cmd );
 805                         $difftext .= $this->debug( "external $wgExternalDiffEngine" );
 806                         wfProfileOut( __METHOD__ . "-shellexec" );
 807                         unlink( $tempName1 );
 808                         unlink( $tempName2 );
 809                         wfProfileOut( __METHOD__ );
 810                         return $difftext;
 811                 }
 812
 813                 # Native PHP diff
 814                 $ota = explode( "\n", $wgContLang->segmentForDiff( $otext ) );
 815                 $nta = explode( "\n", $wgContLang->segmentForDiff( $ntext ) );
 816                 $diffs = new Diff( $ota, $nta );
 817                 $formatter = new TableDiffFormatter();
 818                 $difftext = $wgContLang->unsegmentForDiff( $formatter->format( $diffs ) ) .
 819                 wfProfileOut( __METHOD__ );
 820                 return $difftext;
 821         }
 822
 823         /**
 824          * Generate a debug comment indicating diff generating time,
 825          * server node, and generator backend.
 826          * @return string
 827          */
 828         protected function debug( $generator = "internal" ) {
 829                 global $wgShowHostnames;
 830                 if ( !$this->enableDebugComment ) {
 831                         return '';
 832                 }
 833                 $data = array( $generator );
 834                 if ( $wgShowHostnames ) {
 835                         $data[] = wfHostname();
 836                 }
 837                 $data[] = wfTimestamp( TS_DB );
 838                 return "<!-- diff generator: " .
 839                 implode( " ",
 840                 array_map(
 841                                         "htmlspecialchars",
 842                 $data ) ) .
 843                         " -->\n";
 844         }
 845
 846         /**
 847          * Replace line numbers with the text in the user's language
 848          * @return mixed
 849          */
 850         function localiseLineNumbers( $text ) {
 851                 return preg_replace_callback( '/<!--LINE (\d+)-->/',
 852                 array( &$this, 'localiseLineNumbersCb' ), $text );
 853         }
 854
 855         function localiseLineNumbersCb( $matches ) {
 856                 if ( $matches[1] === '1' && $this->mReducedLineNumbers ) return '';
 857                 return $this->msg( 'lineno' )->numParams( $matches[1] )->escaped();
 858         }
 859
 860
 861         /**
 862          * If there are revisions between the ones being compared, return a note saying so.
 863          * @return string
 864          */
 865         function getMultiNotice() {
 866                 if ( !is_object( $this->mOldRev ) || !is_object( $this->mNewRev ) ) {
 867                         return '';
 868                 } elseif ( !$this->mOldPage->equals( $this->mNewPage ) ) {
 869                         // Comparing two different pages? Count would be meaningless.
 870                         return '';
 871                 }
 872
 873                 if ( $this->mOldRev->getTimestamp() > $this->mNewRev->getTimestamp() ) {
 874                         $oldRev = $this->mNewRev; // flip
 875                         $newRev = $this->mOldRev; // flip
 876                 } else { // normal case
 877                         $oldRev = $this->mOldRev;
 878                         $newRev = $this->mNewRev;
 879                 }
 880
 881                 $nEdits = $this->mNewPage->countRevisionsBetween( $oldRev, $newRev );
 882                 if ( $nEdits > 0 ) {
 883                         $limit = 100; // use diff-multi-manyusers if too many users
 884                         $numUsers = $this->mNewPage->countAuthorsBetween( $oldRev, $newRev, $limit );
 885                         return self::intermediateEditsMsg( $nEdits, $numUsers, $limit );
 886                 }
 887                 return ''; // nothing
 888         }
 889
 890         /**
 891          * Get a notice about how many intermediate edits and users there are
 892          * @param $numEdits int
 893          * @param $numUsers int
 894          * @param $limit int
 895          * @return string
 896          */
 897         public static function intermediateEditsMsg( $numEdits, $numUsers, $limit ) {
 898                 if ( $numUsers > $limit ) {
 899                         $msg = 'diff-multi-manyusers';
 900                         $numUsers = $limit;
 901                 } else {
 902                         $msg = 'diff-multi';
 903                 }
 904                 return wfMessage( $msg )->numParams( $numEdits, $numUsers )->parse();
 905         }
 906
 907         /**
 908          * Get a header for a specified revision.
 909          *
 910          * @param $rev Revision
 911          * @param $complete String: 'complete' to get the header wrapped depending
 912          *        the visibility of the revision and a link to edit the page.
 913          * @return String HTML fragment
 914          */
 915         protected function getRevisionHeader( Revision $rev, $complete = '' ) {
 916                 $lang = $this->getLanguage();
 917                 $user = $this->getUser();
 918                 $revtimestamp = $rev->getTimestamp();
 919                 $timestamp = $lang->userTimeAndDate( $revtimestamp, $user );
 920                 $dateofrev = $lang->userDate( $revtimestamp, $user );
 921                 $timeofrev = $lang->userTime( $revtimestamp, $user );
 922
 923                 $header = $this->msg(
 924                         $rev->isCurrent() ? 'currentrev-asof' : 'revisionasof',
 925                         $timestamp,
 926                         $dateofrev,
 927                         $timeofrev
 928                 )->escaped();
 929
 930                 if ( $complete !== 'complete' ) {
 931                         return $header;
 932                 }
 933
 934                 $title = $rev->getTitle();
 935
 936                 $header = Linker::linkKnown( $title, $header, array(),
 937                         array( 'oldid' => $rev->getID() ) );
 938
 939                 if ( $rev->userCan( Revision::DELETED_TEXT, $user ) ) {
 940                         $editQuery = array( 'action' => 'edit' );
 941                         if ( !$rev->isCurrent() ) {
 942                                 $editQuery['oldid'] = $rev->getID();
 943                         }
 944
 945                         $msg = $this->msg( $title->quickUserCan( 'edit', $user ) ? 'editold' : 'viewsourceold' )->escaped();
 946                         $header .= ' ' . $this->msg( 'parentheses' )->rawParams(
 947                                 Linker::linkKnown( $title, $msg, array(), $editQuery ) )->plain();
 948                         if ( $rev->isDeleted( Revision::DELETED_TEXT ) ) {
 949                                 $header = Html::rawElement( 'span', array( 'class' => 'history-deleted' ), $header );
 950                         }
 951                 } else {
 952                         $header = Html::rawElement( 'span', array( 'class' => 'history-deleted' ), $header );
 953                 }
 954
 955                 return $header;
 956         }
 957
 958         /**
 959          * Add the header to a diff body
 960          *
 961          * @return string
 962          */
 963         function addHeader( $diff, $otitle, $ntitle, $multi = '', $notice = '' ) {
 964                 // shared.css sets diff in interface language/dir, but the actual content
 965                 // is often in a different language, mostly the page content language/dir
 966                 $tableClass = 'diff diff-contentalign-' . htmlspecialchars( $this->getDiffLang()->alignStart() );
 967                 $header = "<table class='$tableClass'>";
 968
 969                 if ( !$diff && !$otitle ) {
 970                         $header .= "
 971                         <tr style='vertical-align: top;'>
 972                         <td class='diff-ntitle'>{$ntitle}</td>
 973                         </tr>";
 974                         $multiColspan = 1;
 975                 } else {
 976                         if ( $diff ) { // Safari/Chrome show broken output if cols not used
 977                                 $header .= "
 978                                 <col class='diff-marker' />
 979                                 <col class='diff-content' />
 980                                 <col class='diff-marker' />
 981                                 <col class='diff-content' />";
 982                                 $colspan = 2;
 983                                 $multiColspan = 4;
 984                         } else {
 985                                 $colspan = 1;
 986                                 $multiColspan = 2;
 987                         }
 988                         $header .= "
 989                         <tr style='vertical-align: top;'>
 990                         <td colspan='$colspan' class='diff-otitle'>{$otitle}</td>
 991                         <td colspan='$colspan' class='diff-ntitle'>{$ntitle}</td>
 992                         </tr>";
 993                 }
 994
 995                 if ( $multi != '' ) {
 996                         $header .= "<tr><td colspan='{$multiColspan}' style='text-align: center;' class='diff-multi'>{$multi}</td></tr>";
 997                 }
 998                 if ( $notice != '' ) {
 999                         $header .= "<tr><td colspan='{$multiColspan}' style='text-align: center;'>{$notice}</td></tr>";
1000                 }
1001
1002                 return $header . $diff . "</table>";
1003         }
1004
1005         /**
1006          * Use specified text instead of loading from the database
1007          * @deprecated since 1.21, use setContent() instead.
1008          */
1009         function setText( $oldText, $newText ) {
1010                 wfDeprecated( __METHOD__, "1.21" );
1011
1012                 $oldContent = ContentHandler::makeContent( $oldText, $this->getTitle() );
1013                 $newContent = ContentHandler::makeContent( $newText, $this->getTitle() );
1014
1015                 $this->setContent( $oldContent, $newContent );
1016         }
1017
1018         /**
1019          * Use specified text instead of loading from the database
1020          * @since 1.21
1021          */
1022         function setContent( Content $oldContent, Content $newContent ) {
1023                 $this->mOldContent = $oldContent;
1024                 $this->mNewContent = $newContent;
1025
1026                 $this->mTextLoaded = 2;
1027                 $this->mRevisionsLoaded = true;
1028         }
1029
1030         /**
1031          * Set the language in which the diff text is written
1032          * (Defaults to page content language).
1033          * @since 1.19
1034          */
1035         function setTextLanguage( $lang ) {
1036                 $this->mDiffLang = wfGetLangObj( $lang );
1037         }
1038
1039         /**
1040          * Load revision IDs
1041          */
1042         private function loadRevisionIds() {
1043                 if ( $this->mRevisionsIdsLoaded ) {
1044                         return;
1045                 }
1046
1047                 $this->mRevisionsIdsLoaded = true;
1048
1049                 $old = $this->mOldid;
1050                 $new = $this->mNewid;
1051
1052                 if ( $new === 'prev' ) {
1053                         # Show diff between revision $old and the previous one.
1054                         # Get previous one from DB.
1055                         $this->mNewid = intval( $old );
1056                         $this->mOldid = $this->getTitle()->getPreviousRevisionID( $this->mNewid );
1057                 } elseif ( $new === 'next' ) {
1058                         # Show diff between revision $old and the next one.
1059                         # Get next one from DB.
1060                         $this->mOldid = intval( $old );
1061                         $this->mNewid = $this->getTitle()->getNextRevisionID( $this->mOldid );
1062                         if ( $this->mNewid === false ) {
1063                                 # if no result, NewId points to the newest old revision. The only newer
1064                                 # revision is cur, which is "0".
1065                                 $this->mNewid = 0;
1066                         }
1067                 } else {
1068                         $this->mOldid = intval( $old );
1069                         $this->mNewid = intval( $new );
1070                         wfRunHooks( 'NewDifferenceEngine', array( $this->getTitle(), &$this->mOldid, &$this->mNewid, $old, $new ) );
1071                 }
1072         }
1073
1074         /**
1075          * Load revision metadata for the specified articles. If newid is 0, then compare
1076          * the old article in oldid to the current article; if oldid is 0, then
1077          * compare the current article to the immediately previous one (ignoring the
1078          * value of newid).
1079          *
1080          * If oldid is false, leave the corresponding revision object set
1081          * to false. This is impossible via ordinary user input, and is provided for
1082          * API convenience.
1083          *
1084          * @return bool
1085          */
1086         function loadRevisionData() {
1087                 if ( $this->mRevisionsLoaded ) {
1088                         return true;
1089                 }
1090
1091                 // Whether it succeeds or fails, we don't want to try again
1092                 $this->mRevisionsLoaded = true;
1093
1094                 $this->loadRevisionIds();
1095
1096                 // Load the new revision object
1097                 $this->mNewRev = $this->mNewid
1098                         ? Revision::newFromId( $this->mNewid )
1099                         : Revision::newFromTitle( $this->getTitle(), false, Revision::READ_NORMAL );
1100
1101                 if ( !$this->mNewRev instanceof Revision ) {
1102                         return false;
1103                 }
1104
1105                 // Update the new revision ID in case it was 0 (makes life easier doing UI stuff)
1106                 $this->mNewid = $this->mNewRev->getId();
1107                 $this->mNewPage = $this->mNewRev->getTitle();
1108
1109                 // Load the old revision object
1110                 $this->mOldRev = false;
1111                 if ( $this->mOldid ) {
1112                         $this->mOldRev = Revision::newFromId( $this->mOldid );
1113                 } elseif ( $this->mOldid === 0 ) {
1114                         $rev = $this->mNewRev->getPrevious();
1115                         if ( $rev ) {
1116                                 $this->mOldid = $rev->getId();
1117                                 $this->mOldRev = $rev;
1118                         } else {
1119                                 // No previous revision; mark to show as first-version only.
1120                                 $this->mOldid = false;
1121                                 $this->mOldRev = false;
1122                         }
1123                 } /* elseif ( $this->mOldid === false ) leave mOldRev false; */
1124
1125                 if ( is_null( $this->mOldRev ) ) {
1126                         return false;
1127                 }
1128
1129                 if ( $this->mOldRev ) {
1130                         $this->mOldPage = $this->mOldRev->getTitle();
1131                 }
1132
1133                 return true;
1134         }
1135
1136         /**
1137          * Load the text of the revisions, as well as revision data.
1138          *
1139          * @return bool
1140          */
1141         function loadText() {
1142                 if ( $this->mTextLoaded == 2 ) {
1143                         return true;
1144                 } else {
1145                         // Whether it succeeds or fails, we don't want to try again
1146                         $this->mTextLoaded = 2;
1147                 }
1148
1149                 if ( !$this->loadRevisionData() ) {
1150                         return false;
1151                 }
1152                 if ( $this->mOldRev ) {
1153                         $this->mOldContent = $this->mOldRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1154                         if ( $this->mOldContent === false ) {
1155                                 return false;
1156                         }
1157                 }
1158                 if ( $this->mNewRev ) {
1159                         $this->mNewContent = $this->mNewRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1160                         if ( $this->mNewContent === false ) {
1161                                 return false;
1162                         }
1163                 }
1164                 return true;
1165         }
1166
1167         /**
1168          * Load the text of the new revision, not the old one
1169          *
1170          * @return bool
1171          */
1172         function loadNewText() {
1173                 if ( $this->mTextLoaded >= 1 ) {
1174                         return true;
1175                 } else {
1176                         $this->mTextLoaded = 1;
1177                 }
1178                 if ( !$this->loadRevisionData() ) {
1179                         return false;
1180                 }
1181                 $this->mNewContent = $this->mNewRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1182                 return true;
1183         }
1184 }