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->mContentObject->getParserOutput();
 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 = ParserOptions::newFromContext( $this->getContext() );
 561                 $parserOptions->enableLimitReport();
 562                 $parserOptions->setTidy( true );
 563
 564                 if ( !$rev->isCurrent() || !$rev->getTitle()->quickUserCan( "edit" ) ) {
 565                         $parserOptions->setEditSection( false );
 566                 }
 567
 568                 $parserOutput = $page->getParserOutput( $parserOptions, $rev->getId() );
 569                 return $parserOutput;
 570         }
 571
 572         /**
 573          * Get the diff text, send it to the OutputPage object
 574          * Returns false if the diff could not be generated, otherwise returns true
 575          *
 576          * @return bool
 577          */
 578         function showDiff( $otitle, $ntitle, $notice = '' ) {
 579                 $diff = $this->getDiff( $otitle, $ntitle, $notice );
 580                 if ( $diff === false ) {
 581                         $this->showMissingRevision();
 582                         return false;
 583                 } else {
 584                         $this->showDiffStyle();
 585                         $this->getOutput()->addHTML( $diff );
 586                         return true;
 587                 }
 588         }
 589
 590         /**
 591          * Add style sheets and supporting JS for diff display.
 592          */
 593         function showDiffStyle() {
 594                 $this->getOutput()->addModuleStyles( 'mediawiki.action.history.diff' );
 595         }
 596
 597         /**
 598          * Get complete diff table, including header
 599          *
 600          * @param $otitle Title: old title
 601          * @param $ntitle Title: new title
 602          * @param $notice String: HTML between diff header and body
 603          * @return mixed
 604          */
 605         function getDiff( $otitle, $ntitle, $notice = '' ) {
 606                 $body = $this->getDiffBody();
 607                 if ( $body === false ) {
 608                         return false;
 609                 } else {
 610                         $multi = $this->getMultiNotice();
 611                         return $this->addHeader( $body, $otitle, $ntitle, $multi, $notice );
 612                 }
 613         }
 614
 615         /**
 616          * Get the diff table body, without header
 617          *
 618          * @return mixed (string/false)
 619          */
 620         public function getDiffBody() {
 621                 global $wgMemc;
 622                 wfProfileIn( __METHOD__ );
 623                 $this->mCacheHit = true;
 624                 // Check if the diff should be hidden from this user
 625                 if ( !$this->loadRevisionData() ) {
 626                         wfProfileOut( __METHOD__ );
 627                         return false;
 628                 } elseif ( $this->mOldRev && !$this->mOldRev->userCan( Revision::DELETED_TEXT, $this->getUser() ) ) {
 629                         wfProfileOut( __METHOD__ );
 630                         return false;
 631                 } elseif ( $this->mNewRev && !$this->mNewRev->userCan( Revision::DELETED_TEXT, $this->getUser() ) ) {
 632                         wfProfileOut( __METHOD__ );
 633                         return false;
 634                 }
 635                 // Short-circuit
 636                 // If mOldRev is false, it means that the
 637                 if ( $this->mOldRev === false || ( $this->mOldRev && $this->mNewRev
 638                         && $this->mOldRev->getID() == $this->mNewRev->getID() ) )
 639                 {
 640                         wfProfileOut( __METHOD__ );
 641                         return '';
 642                 }
 643                 // Cacheable?
 644                 $key = false;
 645                 if ( $this->mOldid && $this->mNewid ) {
 646                         $key = wfMemcKey( 'diff', 'version', MW_DIFF_VERSION,
 647                                 'oldid', $this->mOldid, 'newid', $this->mNewid );
 648                         // Try cache
 649                         if ( !$this->mRefreshCache ) {
 650                                 $difftext = $wgMemc->get( $key );
 651                                 if ( $difftext ) {
 652                                         wfIncrStats( 'diff_cache_hit' );
 653                                         $difftext = $this->localiseLineNumbers( $difftext );
 654                                         $difftext .= "\n<!-- diff cache key $key -->\n";
 655                                         wfProfileOut( __METHOD__ );
 656                                         return $difftext;
 657                                 }
 658                         } // don't try to load but save the result
 659                 }
 660                 $this->mCacheHit = false;
 661
 662                 // Loadtext is permission safe, this just clears out the diff
 663                 if ( !$this->loadText() ) {
 664                         wfProfileOut( __METHOD__ );
 665                         return false;
 666                 }
 667
 668                 $difftext = $this->generateContentDiffBody( $this->mOldContent, $this->mNewContent );
 669
 670                 // Save to cache for 7 days
 671                 if ( !wfRunHooks( 'AbortDiffCache', array( &$this ) ) ) {
 672                         wfIncrStats( 'diff_uncacheable' );
 673                 } elseif ( $key !== false && $difftext !== false ) {
 674                         wfIncrStats( 'diff_cache_miss' );
 675                         $wgMemc->set( $key, $difftext, 7 * 86400 );
 676                 } else {
 677                         wfIncrStats( 'diff_uncacheable' );
 678                 }
 679                 // Replace line numbers with the text in the user's language
 680                 if ( $difftext !== false ) {
 681                         $difftext = $this->localiseLineNumbers( $difftext );
 682                 }
 683                 wfProfileOut( __METHOD__ );
 684                 return $difftext;
 685         }
 686
 687         /**
 688          * Make sure the proper modules are loaded before we try to
 689          * make the diff
 690          */
 691         private function initDiffEngines() {
 692                 global $wgExternalDiffEngine;
 693                 if ( $wgExternalDiffEngine == 'wikidiff' && !function_exists( 'wikidiff_do_diff' ) ) {
 694                         wfProfileIn( __METHOD__ . '-php_wikidiff.so' );
 695                         wfDl( 'php_wikidiff' );
 696                         wfProfileOut( __METHOD__ . '-php_wikidiff.so' );
 697                 }
 698                 elseif ( $wgExternalDiffEngine == 'wikidiff2' && !function_exists( 'wikidiff2_do_diff' ) ) {
 699                         wfProfileIn( __METHOD__ . '-php_wikidiff2.so' );
 700                         wfDl( 'wikidiff2' );
 701                         wfProfileOut( __METHOD__ . '-php_wikidiff2.so' );
 702                 }
 703         }
 704
 705         /**
 706          * Generate a diff, no caching.
 707          *
 708          * Subclasses may override this to provide a
 709          *
 710          * @param $old Content: old content
 711          * @param $new Content: new content
 712          *
 713          * @since 1.WD
 714          */
 715         function generateContentDiffBody( Content $old, Content $new ) {
 716                 if ( !( $old instanceof TextContent ) ) {
 717                         throw new MWException( "Diff not implemented for " . get_class( $old ) . "; "
 718                                                                 . "override generateContentDiffBody to fix this." );
 719                 }
 720
 721                 if ( !( $new instanceof TextContent ) ) {
 722                         throw new MWException( "Diff not implemented for " . get_class( $new ) . "; "
 723                                 . "override generateContentDiffBody to fix this." );
 724                 }
 725
 726                 $otext = $old->serialize();
 727                 $ntext = $new->serialize();
 728
 729                 return $this->generateTextDiffBody( $otext, $ntext );
 730         }
 731
 732         /**
 733          * Generate a diff, no caching
 734          *
 735          * @param $otext String: old text, must be already segmented
 736          * @param $ntext String: new text, must be already segmented
 737          * @deprecated since 1.WD, use generateContentDiffBody() instead!
 738          */
 739         function generateDiffBody( $otext, $ntext ) {
 740                 wfDeprecated( __METHOD__, "1.WD" );
 741
 742                 return $this->generateTextDiffBody( $otext, $ntext );
 743         }
 744
 745         /**
 746          * Generate a diff, no caching
 747          *
 748          * @todo move this to TextDifferenceEngine, make DifferenceEngine abstract. At some point.
 749          *
 750          * @param $otext String: old text, must be already segmented
 751          * @param $ntext String: new text, must be already segmented
 752          * @return bool|string
 753          */
 754         function generateTextDiffBody( $otext, $ntext ) {
 755                 global $wgExternalDiffEngine, $wgContLang;
 756
 757                 wfProfileIn( __METHOD__ );
 758
 759                 $otext = str_replace( "\r\n", "\n", $otext );
 760                 $ntext = str_replace( "\r\n", "\n", $ntext );
 761
 762                 $this->initDiffEngines();
 763
 764                 if ( $wgExternalDiffEngine == 'wikidiff' && function_exists( 'wikidiff_do_diff' ) ) {
 765                         # For historical reasons, external diff engine expects
 766                         # input text to be HTML-escaped already
 767                         $otext = htmlspecialchars ( $wgContLang->segmentForDiff( $otext ) );
 768                         $ntext = htmlspecialchars ( $wgContLang->segmentForDiff( $ntext ) );
 769                         wfProfileOut( __METHOD__ );
 770                         return $wgContLang->unsegmentForDiff( wikidiff_do_diff( $otext, $ntext, 2 ) ) .
 771                         $this->debug( 'wikidiff1' );
 772                 }
 773
 774                 if ( $wgExternalDiffEngine == 'wikidiff2' && function_exists( 'wikidiff2_do_diff' ) ) {
 775                         # Better external diff engine, the 2 may some day be dropped
 776                         # This one does the escaping and segmenting itself
 777                         wfProfileIn( 'wikidiff2_do_diff' );
 778                         $text = wikidiff2_do_diff( $otext, $ntext, 2 );
 779                         $text .= $this->debug( 'wikidiff2' );
 780                         wfProfileOut( 'wikidiff2_do_diff' );
 781                         wfProfileOut( __METHOD__ );
 782                         return $text;
 783                 }
 784                 if ( $wgExternalDiffEngine != 'wikidiff3' && $wgExternalDiffEngine !== false ) {
 785                         # Diff via the shell
 786                         $tmpDir = wfTempDir();
 787                         $tempName1 = tempnam( $tmpDir, 'diff_' );
 788                         $tempName2 = tempnam( $tmpDir, 'diff_' );
 789
 790                         $tempFile1 = fopen( $tempName1, "w" );
 791                         if ( !$tempFile1 ) {
 792                                 wfProfileOut( __METHOD__ );
 793                                 return false;
 794                         }
 795                         $tempFile2 = fopen( $tempName2, "w" );
 796                         if ( !$tempFile2 ) {
 797                                 wfProfileOut( __METHOD__ );
 798                                 return false;
 799                         }
 800                         fwrite( $tempFile1, $otext );
 801                         fwrite( $tempFile2, $ntext );
 802                         fclose( $tempFile1 );
 803                         fclose( $tempFile2 );
 804                         $cmd = wfEscapeShellArg( $wgExternalDiffEngine, $tempName1, $tempName2 );
 805                         wfProfileIn( __METHOD__ . "-shellexec" );
 806                         $difftext = wfShellExec( $cmd );
 807                         $difftext .= $this->debug( "external $wgExternalDiffEngine" );
 808                         wfProfileOut( __METHOD__ . "-shellexec" );
 809                         unlink( $tempName1 );
 810                         unlink( $tempName2 );
 811                         wfProfileOut( __METHOD__ );
 812                         return $difftext;
 813                 }
 814
 815                 # Native PHP diff
 816                 $ota = explode( "\n", $wgContLang->segmentForDiff( $otext ) );
 817                 $nta = explode( "\n", $wgContLang->segmentForDiff( $ntext ) );
 818                 $diffs = new Diff( $ota, $nta );
 819                 $formatter = new TableDiffFormatter();
 820                 $difftext = $wgContLang->unsegmentForDiff( $formatter->format( $diffs ) ) .
 821                 wfProfileOut( __METHOD__ );
 822                 return $difftext;
 823         }
 824
 825         /**
 826          * Generate a debug comment indicating diff generating time,
 827          * server node, and generator backend.
 828          * @return string
 829          */
 830         protected function debug( $generator = "internal" ) {
 831                 global $wgShowHostnames;
 832                 if ( !$this->enableDebugComment ) {
 833                         return '';
 834                 }
 835                 $data = array( $generator );
 836                 if ( $wgShowHostnames ) {
 837                         $data[] = wfHostname();
 838                 }
 839                 $data[] = wfTimestamp( TS_DB );
 840                 return "<!-- diff generator: " .
 841                 implode( " ",
 842                 array_map(
 843                                         "htmlspecialchars",
 844                 $data ) ) .
 845                         " -->\n";
 846         }
 847
 848         /**
 849          * Replace line numbers with the text in the user's language
 850          * @return mixed
 851          */
 852         function localiseLineNumbers( $text ) {
 853                 return preg_replace_callback( '/<!--LINE (\d+)-->/',
 854                 array( &$this, 'localiseLineNumbersCb' ), $text );
 855         }
 856
 857         function localiseLineNumbersCb( $matches ) {
 858                 if ( $matches[1] === '1' && $this->mReducedLineNumbers ) return '';
 859                 return $this->msg( 'lineno' )->numParams( $matches[1] )->escaped();
 860         }
 861
 862
 863         /**
 864          * If there are revisions between the ones being compared, return a note saying so.
 865          * @return string
 866          */
 867         function getMultiNotice() {
 868                 if ( !is_object( $this->mOldRev ) || !is_object( $this->mNewRev ) ) {
 869                         return '';
 870                 } elseif ( !$this->mOldPage->equals( $this->mNewPage ) ) {
 871                         // Comparing two different pages? Count would be meaningless.
 872                         return '';
 873                 }
 874
 875                 if ( $this->mOldRev->getTimestamp() > $this->mNewRev->getTimestamp() ) {
 876                         $oldRev = $this->mNewRev; // flip
 877                         $newRev = $this->mOldRev; // flip
 878                 } else { // normal case
 879                         $oldRev = $this->mOldRev;
 880                         $newRev = $this->mNewRev;
 881                 }
 882
 883                 $nEdits = $this->mNewPage->countRevisionsBetween( $oldRev, $newRev );
 884                 if ( $nEdits > 0 ) {
 885                         $limit = 100; // use diff-multi-manyusers if too many users
 886                         $numUsers = $this->mNewPage->countAuthorsBetween( $oldRev, $newRev, $limit );
 887                         return self::intermediateEditsMsg( $nEdits, $numUsers, $limit );
 888                 }
 889                 return ''; // nothing
 890         }
 891
 892         /**
 893          * Get a notice about how many intermediate edits and users there are
 894          * @param $numEdits int
 895          * @param $numUsers int
 896          * @param $limit int
 897          * @return string
 898          */
 899         public static function intermediateEditsMsg( $numEdits, $numUsers, $limit ) {
 900                 if ( $numUsers > $limit ) {
 901                         $msg = 'diff-multi-manyusers';
 902                         $numUsers = $limit;
 903                 } else {
 904                         $msg = 'diff-multi';
 905                 }
 906                 return wfMessage( $msg )->numParams( $numEdits, $numUsers )->parse();
 907         }
 908
 909         /**
 910          * Get a header for a specified revision.
 911          *
 912          * @param $rev Revision
 913          * @param $complete String: 'complete' to get the header wrapped depending
 914          *        the visibility of the revision and a link to edit the page.
 915          * @return String HTML fragment
 916          */
 917         protected function getRevisionHeader( Revision $rev, $complete = '' ) {
 918                 $lang = $this->getLanguage();
 919                 $user = $this->getUser();
 920                 $revtimestamp = $rev->getTimestamp();
 921                 $timestamp = $lang->userTimeAndDate( $revtimestamp, $user );
 922                 $dateofrev = $lang->userDate( $revtimestamp, $user );
 923                 $timeofrev = $lang->userTime( $revtimestamp, $user );
 924
 925                 $header = $this->msg(
 926                         $rev->isCurrent() ? 'currentrev-asof' : 'revisionasof',
 927                         $timestamp,
 928                         $dateofrev,
 929                         $timeofrev
 930                 )->escaped();
 931
 932                 if ( $complete !== 'complete' ) {
 933                         return $header;
 934                 }
 935
 936                 $title = $rev->getTitle();
 937
 938                 $header = Linker::linkKnown( $title, $header, array(),
 939                         array( 'oldid' => $rev->getID() ) );
 940
 941                 if ( $rev->userCan( Revision::DELETED_TEXT, $user ) ) {
 942                         $editQuery = array( 'action' => 'edit' );
 943                         if ( !$rev->isCurrent() ) {
 944                                 $editQuery['oldid'] = $rev->getID();
 945                         }
 946
 947                         $msg = $this->msg( $title->quickUserCan( 'edit', $user ) ? 'editold' : 'viewsourceold' )->escaped();
 948                         $header .= ' ' . $this->msg( 'parentheses' )->rawParams(
 949                                 Linker::linkKnown( $title, $msg, array(), $editQuery ) )->plain();
 950                         if ( $rev->isDeleted( Revision::DELETED_TEXT ) ) {
 951                                 $header = Html::rawElement( 'span', array( 'class' => 'history-deleted' ), $header );
 952                         }
 953                 } else {
 954                         $header = Html::rawElement( 'span', array( 'class' => 'history-deleted' ), $header );
 955                 }
 956
 957                 return $header;
 958         }
 959
 960         /**
 961          * Add the header to a diff body
 962          *
 963          * @return string
 964          */
 965         function addHeader( $diff, $otitle, $ntitle, $multi = '', $notice = '' ) {
 966                 // shared.css sets diff in interface language/dir, but the actual content
 967                 // is often in a different language, mostly the page content language/dir
 968                 $tableClass = 'diff diff-contentalign-' . htmlspecialchars( $this->getDiffLang()->alignStart() );
 969                 $header = "<table class='$tableClass'>";
 970
 971                 if ( !$diff && !$otitle ) {
 972                         $header .= "
 973                         <tr style='vertical-align: top;'>
 974                         <td class='diff-ntitle'>{$ntitle}</td>
 975                         </tr>";
 976                         $multiColspan = 1;
 977                 } else {
 978                         if ( $diff ) { // Safari/Chrome show broken output if cols not used
 979                                 $header .= "
 980                                 <col class='diff-marker' />
 981                                 <col class='diff-content' />
 982                                 <col class='diff-marker' />
 983                                 <col class='diff-content' />";
 984                                 $colspan = 2;
 985                                 $multiColspan = 4;
 986                         } else {
 987                                 $colspan = 1;
 988                                 $multiColspan = 2;
 989                         }
 990                         $header .= "
 991                         <tr style='vertical-align: top;'>
 992                         <td colspan='$colspan' class='diff-otitle'>{$otitle}</td>
 993                         <td colspan='$colspan' class='diff-ntitle'>{$ntitle}</td>
 994                         </tr>";
 995                 }
 996
 997                 if ( $multi != '' ) {
 998                         $header .= "<tr><td colspan='{$multiColspan}' style='text-align: center;' class='diff-multi'>{$multi}</td></tr>";
 999                 }
1000                 if ( $notice != '' ) {
1001                         $header .= "<tr><td colspan='{$multiColspan}' style='text-align: center;'>{$notice}</td></tr>";
1002                 }
1003
1004                 return $header . $diff . "</table>";
1005         }
1006
1007         /**
1008          * Use specified text instead of loading from the database
1009          * @deprecated since 1.WD, use setContent() instead.
1010          */
1011         function setText( $oldText, $newText ) {
1012                 wfDeprecated( __METHOD__, "1.WD" );
1013
1014                 $oldContent = ContentHandler::makeContent( $oldText, $this->getTitle() );
1015                 $newContent = ContentHandler::makeContent( $newText, $this->getTitle() );
1016
1017                 $this->setContent( $oldContent, $newContent );
1018         }
1019
1020         /**
1021          * Use specified text instead of loading from the database
1022          * @since 1.WD
1023          */
1024         function setContent( Content $oldContent, Content $newContent ) {
1025                 $this->mOldContent = $oldContent;
1026                 $this->mNewContent = $newContent;
1027
1028                 $this->mTextLoaded = 2;
1029                 $this->mRevisionsLoaded = true;
1030         }
1031
1032         /**
1033          * Set the language in which the diff text is written
1034          * (Defaults to page content language).
1035          * @since 1.19
1036          */
1037         function setTextLanguage( $lang ) {
1038                 $this->mDiffLang = wfGetLangObj( $lang );
1039         }
1040
1041         /**
1042          * Load revision IDs
1043          */
1044         private function loadRevisionIds() {
1045                 if ( $this->mRevisionsIdsLoaded ) {
1046                         return;
1047                 }
1048
1049                 $this->mRevisionsIdsLoaded = true;
1050
1051                 $old = $this->mOldid;
1052                 $new = $this->mNewid;
1053
1054                 if ( $new === 'prev' ) {
1055                         # Show diff between revision $old and the previous one.
1056                         # Get previous one from DB.
1057                         $this->mNewid = intval( $old );
1058                         $this->mOldid = $this->getTitle()->getPreviousRevisionID( $this->mNewid );
1059                 } elseif ( $new === 'next' ) {
1060                         # Show diff between revision $old and the next one.
1061                         # Get next one from DB.
1062                         $this->mOldid = intval( $old );
1063                         $this->mNewid = $this->getTitle()->getNextRevisionID( $this->mOldid );
1064                         if ( $this->mNewid === false ) {
1065                                 # if no result, NewId points to the newest old revision. The only newer
1066                                 # revision is cur, which is "0".
1067                                 $this->mNewid = 0;
1068                         }
1069                 } else {
1070                         $this->mOldid = intval( $old );
1071                         $this->mNewid = intval( $new );
1072                         wfRunHooks( 'NewDifferenceEngine', array( $this->getTitle(), &$this->mOldid, &$this->mNewid, $old, $new ) );
1073                 }
1074         }
1075
1076         /**
1077          * Load revision metadata for the specified articles. If newid is 0, then compare
1078          * the old article in oldid to the current article; if oldid is 0, then
1079          * compare the current article to the immediately previous one (ignoring the
1080          * value of newid).
1081          *
1082          * If oldid is false, leave the corresponding revision object set
1083          * to false. This is impossible via ordinary user input, and is provided for
1084          * API convenience.
1085          *
1086          * @return bool
1087          */
1088         function loadRevisionData() {
1089                 if ( $this->mRevisionsLoaded ) {
1090                         return true;
1091                 }
1092
1093                 // Whether it succeeds or fails, we don't want to try again
1094                 $this->mRevisionsLoaded = true;
1095
1096                 $this->loadRevisionIds();
1097
1098                 // Load the new revision object
1099                 $this->mNewRev = $this->mNewid
1100                         ? Revision::newFromId( $this->mNewid )
1101                         : Revision::newFromTitle( $this->getTitle(), false, Revision::READ_NORMAL );
1102
1103                 if ( !$this->mNewRev instanceof Revision ) {
1104                         return false;
1105                 }
1106
1107                 // Update the new revision ID in case it was 0 (makes life easier doing UI stuff)
1108                 $this->mNewid = $this->mNewRev->getId();
1109                 $this->mNewPage = $this->mNewRev->getTitle();
1110
1111                 // Load the old revision object
1112                 $this->mOldRev = false;
1113                 if ( $this->mOldid ) {
1114                         $this->mOldRev = Revision::newFromId( $this->mOldid );
1115                 } elseif ( $this->mOldid === 0 ) {
1116                         $rev = $this->mNewRev->getPrevious();
1117                         if ( $rev ) {
1118                                 $this->mOldid = $rev->getId();
1119                                 $this->mOldRev = $rev;
1120                         } else {
1121                                 // No previous revision; mark to show as first-version only.
1122                                 $this->mOldid = false;
1123                                 $this->mOldRev = false;
1124                         }
1125                 } /* elseif ( $this->mOldid === false ) leave mOldRev false; */
1126
1127                 if ( is_null( $this->mOldRev ) ) {
1128                         return false;
1129                 }
1130
1131                 if ( $this->mOldRev ) {
1132                         $this->mOldPage = $this->mOldRev->getTitle();
1133                 }
1134
1135                 return true;
1136         }
1137
1138         /**
1139          * Load the text of the revisions, as well as revision data.
1140          *
1141          * @return bool
1142          */
1143         function loadText() {
1144                 if ( $this->mTextLoaded == 2 ) {
1145                         return true;
1146                 } else {
1147                         // Whether it succeeds or fails, we don't want to try again
1148                         $this->mTextLoaded = 2;
1149                 }
1150
1151                 if ( !$this->loadRevisionData() ) {
1152                         return false;
1153                 }
1154                 if ( $this->mOldRev ) {
1155                         $this->mOldContent = $this->mOldRev->getContent( Revision::FOR_THIS_USER );
1156                         if ( $this->mOldContent === false ) {
1157                                 return false;
1158                         }
1159                 }
1160                 if ( $this->mNewRev ) {
1161                         $this->mNewContent = $this->mNewRev->getContent( Revision::FOR_THIS_USER );
1162                         if ( $this->mNewContent === false ) {
1163                                 return false;
1164                         }
1165                 }
1166                 return true;
1167         }
1168
1169         /**
1170          * Load the text of the new revision, not the old one
1171          *
1172          * @return bool
1173          */
1174         function loadNewText() {
1175                 if ( $this->mTextLoaded >= 1 ) {
1176                         return true;
1177                 } else {
1178                         $this->mTextLoaded = 1;
1179                 }
1180                 if ( !$this->loadRevisionData() ) {
1181                         return false;
1182                 }
1183                 $this->mNewContent = $this->mNewRev->getContent( Revision::FOR_THIS_USER );
1184                 return true;
1185         }
1186 }