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         /**
  42          * @var Content
  43          */
  44         var $mOldContent, $mNewContent;
  45         protected $mDiffLang;
  46
  47         /**
  48          * @var Title
  49          */
  50         var $mOldPage, $mNewPage;
  51         var $mRcidMarkPatrolled;
  52
  53         /**
  54          * @var Revision
  55          */
  56         var $mOldRev, $mNewRev;
  57         private $mRevisionsIdsLoaded = false; // Have the revisions IDs been loaded
  58         var $mRevisionsLoaded = false; // Have the revisions been loaded
  59         var $mTextLoaded = 0; // How many text blobs have been loaded, 0, 1 or 2?
  60         var $mCacheHit = false; // Was the diff fetched from cache?
  61
  62         /**
  63          * Set this to true to add debug info to the HTML output.
  64          * Warning: this may cause RSS readers to spuriously mark articles as "new"
  65          * (bug 20601)
  66          */
  67         var $enableDebugComment = false;
  68
  69         // If true, line X is not displayed when X is 1, for example to increase
  70         // readability and conserve space with many small diffs.
  71         protected $mReducedLineNumbers = false;
  72
  73         // Link to action=markpatrolled
  74         protected $mMarkPatrolledLink = null;
  75
  76         protected $unhide = false; # show rev_deleted content if allowed
  77         /**#@-*/
  78
  79         /**
  80          * Constructor
  81          * @param $context IContextSource context to use, anything else will be ignored
  82          * @param $old Integer old ID we want to show and diff with.
  83          * @param string $new either 'prev' or 'next'.
  84          * @param $rcid Integer ??? FIXME (default 0)
  85          * @param $refreshCache boolean If set, refreshes the diff cache
  86          * @param $unhide boolean If set, allow viewing deleted revs
  87          */
  88         function __construct( $context = null, $old = 0, $new = 0, $rcid = 0,
  89                 $refreshCache = false, $unhide = false )
  90         {
  91                 if ( $context instanceof IContextSource ) {
  92                         $this->setContext( $context );
  93                 }
  94
  95                 wfDebug( "DifferenceEngine old '$old' new '$new' rcid '$rcid'\n" );
  96
  97                 $this->mOldid = $old;
  98                 $this->mNewid = $new;
  99                 $this->mRcidMarkPatrolled = intval( $rcid );  # force it to be an integer
 100                 $this->mRefreshCache = $refreshCache;
 101                 $this->unhide = $unhide;
 102         }
 103
 104         /**
 105          * @param $value bool
 106          */
 107         function setReducedLineNumbers( $value = true ) {
 108                 $this->mReducedLineNumbers = $value;
 109         }
 110
 111         /**
 112          * @return Language
 113          */
 114         function getDiffLang() {
 115                 if ( $this->mDiffLang === null ) {
 116                         # Default language in which the diff text is written.
 117                         $this->mDiffLang = $this->getTitle()->getPageLanguage();
 118                 }
 119                 return $this->mDiffLang;
 120         }
 121
 122         /**
 123          * @return bool
 124          */
 125         function wasCacheHit() {
 126                 return $this->mCacheHit;
 127         }
 128
 129         /**
 130          * @return int
 131          */
 132         function getOldid() {
 133                 $this->loadRevisionIds();
 134                 return $this->mOldid;
 135         }
 136
 137         /**
 138          * @return Bool|int
 139          */
 140         function getNewid() {
 141                 $this->loadRevisionIds();
 142                 return $this->mNewid;
 143         }
 144
 145         /**
 146          * Look up a special:Undelete link to the given deleted revision id,
 147          * as a workaround for being unable to load deleted diffs in currently.
 148          *
 149          * @param int $id revision ID
 150          * @return mixed URL or false
 151          */
 152         function deletedLink( $id ) {
 153                 if ( $this->getUser()->isAllowed( 'deletedhistory' ) ) {
 154                         $dbr = wfGetDB( DB_SLAVE );
 155                         $row = $dbr->selectRow( 'archive', '*',
 156                                 array( 'ar_rev_id' => $id ),
 157                                 __METHOD__ );
 158                         if ( $row ) {
 159                                 $rev = Revision::newFromArchiveRow( $row );
 160                                 $title = Title::makeTitleSafe( $row->ar_namespace, $row->ar_title );
 161                                 return SpecialPage::getTitleFor( 'Undelete' )->getFullURL( array(
 162                                         'target' => $title->getPrefixedText(),
 163                                         'timestamp' => $rev->getTimestamp()
 164                                 ));
 165                         }
 166                 }
 167                 return false;
 168         }
 169
 170         /**
 171          * Build a wikitext link toward a deleted revision, if viewable.
 172          *
 173          * @param int $id revision ID
 174          * @return string wikitext fragment
 175          */
 176         function deletedIdMarker( $id ) {
 177                 $link = $this->deletedLink( $id );
 178                 if ( $link ) {
 179                         return "[$link $id]";
 180                 } else {
 181                         return $id;
 182                 }
 183         }
 184
 185         private function showMissingRevision() {
 186                 $out = $this->getOutput();
 187
 188                 $missing = array();
 189                 if ( $this->mOldRev === null ) {
 190                         $missing[] = $this->deletedIdMarker( $this->mOldid );
 191                 }
 192                 if ( $this->mNewRev === null ) {
 193                         $missing[] = $this->deletedIdMarker( $this->mNewid );
 194                 }
 195
 196                 $out->setPageTitle( $this->msg( 'errorpagetitle' ) );
 197                 $out->addWikiMsg( 'difference-missing-revision',
 198                         $this->getLanguage()->listToText( $missing ), count( $missing ) );
 199         }
 200
 201         function showDiffPage( $diffOnly = false ) {
 202                 wfProfileIn( __METHOD__ );
 203
 204                 # Allow frames except in certain special cases
 205                 $out = $this->getOutput();
 206                 $out->allowClickjacking();
 207                 $out->setRobotPolicy( 'noindex,nofollow' );
 208
 209                 if ( !$this->loadRevisionData() ) {
 210                         $this->showMissingRevision();
 211                         wfProfileOut( __METHOD__ );
 212                         return;
 213                 }
 214
 215                 $user = $this->getUser();
 216                 $permErrors = $this->mNewPage->getUserPermissionsErrors( 'read', $user );
 217                 if ( $this->mOldPage ) { # mOldPage might not be set, see below.
 218                         $permErrors = wfMergeErrorArrays( $permErrors,
 219                                 $this->mOldPage->getUserPermissionsErrors( 'read', $user ) );
 220                 }
 221                 if ( count( $permErrors ) ) {
 222                         wfProfileOut( __METHOD__ );
 223                         throw new PermissionsError( 'read', $permErrors );
 224                 }
 225
 226                 # If external diffs are enabled both globally and for the user,
 227                 # we'll use the application/x-external-editor interface to call
 228                 # an external diff tool like kompare, kdiff3, etc.
 229                 if ( ExternalEdit::useExternalEngine( $this->getContext(), 'diff' ) ) {
 230                         //TODO: come up with a good solution for non-text content here.
 231                         //      at least, the content format needs to be passed to the client somehow.
 232                         //      Currently, action=raw will just fail for non-text content.
 233
 234                         $urls = array(
 235                                 'File' => array( 'Extension' => 'wiki', 'URL' =>
 236                                         # This should be mOldPage, but it may not be set, see below.
 237                                         $this->mNewPage->getCanonicalURL( array(
 238                                                 'action' => 'raw', 'oldid' => $this->mOldid ) )
 239                                 ),
 240                                 'File2' => array( 'Extension' => 'wiki', 'URL' =>
 241                                         $this->mNewPage->getCanonicalURL( array(
 242                                                 'action' => 'raw', 'oldid' => $this->mNewid ) )
 243                                 ),
 244                         );
 245
 246                         $externalEditor = new ExternalEdit( $this->getContext(), $urls );
 247                         $externalEditor->execute();
 248
 249                         wfProfileOut( __METHOD__ );
 250                         return;
 251                 }
 252
 253                 $rollback = '';
 254                 $undoLink = '';
 255
 256                 $query = array();
 257                 # Carry over 'diffonly' param via navigation links
 258                 if ( $diffOnly != $user->getBoolOption( 'diffonly' ) ) {
 259                         $query['diffonly'] = $diffOnly;
 260                 }
 261                 # Cascade unhide param in links for easy deletion browsing
 262                 if ( $this->unhide ) {
 263                         $query['unhide'] = 1;
 264                 }
 265
 266                 # Check if one of the revisions is deleted/suppressed
 267                 $deleted = $suppressed = false;
 268                 $allowed = $this->mNewRev->userCan( Revision::DELETED_TEXT, $user );
 269
 270                 $revisionTools = array();
 271
 272                 # mOldRev is false if the difference engine is called with a "vague" query for
 273                 # a diff between a version V and its previous version V' AND the version V
 274                 # is the first version of that article. In that case, V' does not exist.
 275                 if ( $this->mOldRev === false ) {
 276                         $out->setPageTitle( $this->msg( 'difference-title', $this->mNewPage->getPrefixedText() ) );
 277                         $samePage = true;
 278                         $oldHeader = '';
 279                 } else {
 280                         wfRunHooks( 'DiffViewHeader', array( $this, $this->mOldRev, $this->mNewRev ) );
 281
 282                         $sk = $this->getSkin();
 283                         if ( method_exists( $sk, 'suppressQuickbar' ) ) {
 284                                 $sk->suppressQuickbar();
 285                         }
 286
 287                         if ( $this->mNewPage->equals( $this->mOldPage ) ) {
 288                                 $out->setPageTitle( $this->msg( 'difference-title', $this->mNewPage->getPrefixedText() ) );
 289                                 $samePage = true;
 290                         } else {
 291                                 $out->setPageTitle( $this->msg( 'difference-title-multipage', $this->mOldPage->getPrefixedText(),
 292                                         $this->mNewPage->getPrefixedText() ) );
 293                                 $out->addSubtitle( $this->msg( 'difference-multipage' ) );
 294                                 $samePage = false;
 295                         }
 296
 297                         if ( $samePage && $this->mNewPage->quickUserCan( 'edit', $user ) ) {
 298                                 if ( $this->mNewRev->isCurrent() && $this->mNewPage->userCan( 'rollback', $user ) ) {
 299                                         $rollbackLink = Linker::generateRollback( $this->mNewRev, $this->getContext() );
 300                                         if ( $rollbackLink ) {
 301                                                 $out->preventClickjacking();
 302                                                 $rollback = '&#160;&#160;&#160;' . $rollbackLink;
 303                                         }
 304                                 }
 305                                 if ( !$this->mOldRev->isDeleted( Revision::DELETED_TEXT ) && !$this->mNewRev->isDeleted( Revision::DELETED_TEXT ) ) {
 306                                         $undoLink = Html::element( 'a', array(
 307                                                         'href' => $this->mNewPage->getLocalUrl( array(
 308                                                                 'action' => 'edit',
 309                                                                 'undoafter' => $this->mOldid,
 310                                                                 'undo' => $this->mNewid ) ),
 311                                                         'title' => Linker::titleAttrib( 'undo' )
 312                                                 ),
 313                                                 $this->msg( 'editundo' )->text()
 314                                         );
 315                                         $revisionTools[] = $undoLink;
 316                                 }
 317                         }
 318
 319                         # Make "previous revision link"
 320                         if ( $samePage && $this->mOldRev->getPrevious() ) {
 321                                 $prevlink = Linker::linkKnown(
 322                                         $this->mOldPage,
 323                                         $this->msg( 'previousdiff' )->escaped(),
 324                                         array( 'id' => 'differences-prevlink' ),
 325                                         array( 'diff' => 'prev', 'oldid' => $this->mOldid ) + $query
 326                                 );
 327                         } else {
 328                                 $prevlink = '&#160;';
 329                         }
 330
 331                         if ( $this->mOldRev->isMinor() ) {
 332                                 $oldminor = ChangesList::flag( 'minor' );
 333                         } else {
 334                                 $oldminor = '';
 335                         }
 336
 337                         $ldel = $this->revisionDeleteLink( $this->mOldRev );
 338                         $oldRevisionHeader = $this->getRevisionHeader( $this->mOldRev, 'complete' );
 339
 340                         $oldHeader = '<div id="mw-diff-otitle1"><strong>' . $oldRevisionHeader . '</strong></div>' .
 341                                 '<div id="mw-diff-otitle2">' .
 342                                         Linker::revUserTools( $this->mOldRev, !$this->unhide ) . '</div>' .
 343                                 '<div id="mw-diff-otitle3">' . $oldminor .
 344                                         Linker::revComment( $this->mOldRev, !$diffOnly, !$this->unhide ) . $ldel . '</div>' .
 345                                 '<div id="mw-diff-otitle4">' . $prevlink . '</div>';
 346
 347                         if ( $this->mOldRev->isDeleted( Revision::DELETED_TEXT ) ) {
 348                                 $deleted = true; // old revisions text is hidden
 349                                 if ( $this->mOldRev->isDeleted( Revision::DELETED_RESTRICTED ) ) {
 350                                         $suppressed = true; // also suppressed
 351                                 }
 352                         }
 353
 354                         # Check if this user can see the revisions
 355                         if ( !$this->mOldRev->userCan( Revision::DELETED_TEXT, $user ) ) {
 356                                 $allowed = false;
 357                         }
 358                 }
 359
 360                 # Make "next revision link"
 361                 # Skip next link on the top revision
 362                 if ( $samePage && !$this->mNewRev->isCurrent() ) {
 363                         $nextlink = Linker::linkKnown(
 364                                 $this->mNewPage,
 365                                 $this->msg( 'nextdiff' )->escaped(),
 366                                 array( 'id' => 'differences-nextlink' ),
 367                                 array( 'diff' => 'next', 'oldid' => $this->mNewid ) + $query
 368                         );
 369                 } else {
 370                         $nextlink = '&#160;';
 371                 }
 372
 373                 if ( $this->mNewRev->isMinor() ) {
 374                         $newminor = ChangesList::flag( 'minor' );
 375                 } else {
 376                         $newminor = '';
 377                 }
 378
 379                 # Handle RevisionDelete links...
 380                 $rdel = $this->revisionDeleteLink( $this->mNewRev );
 381
 382                 # Allow extensions to define their own revision tools
 383                 wfRunHooks( 'DiffRevisionTools', array( $this->mNewRev, &$revisionTools ) );
 384                 $formattedRevisionTools = array();
 385                 // Put each one in parentheses (poor man's button)
 386                 foreach ( $revisionTools as $tool ) {
 387                         $formattedRevisionTools[] = $this->msg( 'parentheses' )->rawParams( $tool )->escaped();
 388                 }
 389                 $newRevisionHeader = $this->getRevisionHeader( $this->mNewRev, 'complete' ) . ' ' . implode( ' ', $formattedRevisionTools );
 390
 391                 $newHeader = '<div id="mw-diff-ntitle1"><strong>' . $newRevisionHeader . '</strong></div>' .
 392                         '<div id="mw-diff-ntitle2">' . Linker::revUserTools( $this->mNewRev, !$this->unhide ) .
 393                                 " $rollback</div>" .
 394                         '<div id="mw-diff-ntitle3">' . $newminor .
 395                                 Linker::revComment( $this->mNewRev, !$diffOnly, !$this->unhide ) . $rdel . '</div>' .
 396                         '<div id="mw-diff-ntitle4">' . $nextlink . $this->markPatrolledLink() . '</div>';
 397
 398                 if ( $this->mNewRev->isDeleted( Revision::DELETED_TEXT ) ) {
 399                         $deleted = true; // new revisions text is hidden
 400                         if ( $this->mNewRev->isDeleted( Revision::DELETED_RESTRICTED ) )
 401                                 $suppressed = true; // also suppressed
 402                 }
 403
 404                 # If the diff cannot be shown due to a deleted revision, then output
 405                 # the diff header and links to unhide (if available)...
 406                 if ( $deleted && ( !$this->unhide || !$allowed ) ) {
 407                         $this->showDiffStyle();
 408                         $multi = $this->getMultiNotice();
 409                         $out->addHTML( $this->addHeader( '', $oldHeader, $newHeader, $multi ) );
 410                         if ( !$allowed ) {
 411                                 $msg = $suppressed ? 'rev-suppressed-no-diff' : 'rev-deleted-no-diff';
 412                                 # Give explanation for why revision is not visible
 413                                 $out->wrapWikiMsg( "<div id='mw-$msg' class='mw-warning plainlinks'>\n$1\n</div>\n",
 414                                         array( $msg ) );
 415                         } else {
 416                                 # Give explanation and add a link to view the diff...
 417                                 $link = $this->getTitle()->getFullUrl( $this->getRequest()->appendQueryValue( 'unhide', '1', true ) );
 418                                 $msg = $suppressed ? 'rev-suppressed-unhide-diff' : 'rev-deleted-unhide-diff';
 419                                 $out->wrapWikiMsg( "<div id='mw-$msg' class='mw-warning plainlinks'>\n$1\n</div>\n", array( $msg, $link ) );
 420                         }
 421                 # Otherwise, output a regular diff...
 422                 } else {
 423                         # Add deletion notice if the user is viewing deleted content
 424                         $notice = '';
 425                         if ( $deleted ) {
 426                                 $msg = $suppressed ? 'rev-suppressed-diff-view' : 'rev-deleted-diff-view';
 427                                 $notice = "<div id='mw-$msg' class='mw-warning plainlinks'>\n" . $this->msg( $msg )->parse() . "</div>\n";
 428                         }
 429                         $this->showDiff( $oldHeader, $newHeader, $notice );
 430                         if ( !$diffOnly ) {
 431                                 $this->renderNewRevision();
 432                         }
 433                 }
 434                 wfProfileOut( __METHOD__ );
 435         }
 436
 437         /**
 438          * Get a link to mark the change as patrolled, or '' if there's either no
 439          * revision to patrol or the user is not allowed to to it.
 440          * Side effect: When the patrol link is build, this method will call
 441          * OutputPage::preventClickjacking() and load mediawiki.page.patrol.ajax.
 442          *
 443          * @return String
 444          */
 445         protected function markPatrolledLink() {
 446                 global $wgUseRCPatrol;
 447
 448                 if ( $this->mMarkPatrolledLink === null ) {
 449                         // Prepare a change patrol link, if applicable
 450                         if ( $wgUseRCPatrol && $this->mNewPage->quickUserCan( 'patrol', $this->getUser() ) ) {
 451                                 // If we've been given an explicit change identifier, use it; saves time
 452                                 if ( $this->mRcidMarkPatrolled ) {
 453                                         $rcid = $this->mRcidMarkPatrolled;
 454                                         $rc = RecentChange::newFromId( $rcid );
 455                                         // Already patrolled?
 456                                         $rcid = is_object( $rc ) && !$rc->getAttribute( 'rc_patrolled' ) ? $rcid : 0;
 457                                 } else {
 458                                         // Look for an unpatrolled change corresponding to this diff
 459                                         $db = wfGetDB( DB_SLAVE );
 460                                         $change = RecentChange::newFromConds(
 461                                                 array(
 462                                                 // Redundant user,timestamp condition so we can use the existing index
 463                                                         'rc_user_text'  => $this->mNewRev->getRawUserText(),
 464                                                         'rc_timestamp'  => $db->timestamp( $this->mNewRev->getTimestamp() ),
 465                                                         'rc_this_oldid' => $this->mNewid,
 466                                                         'rc_last_oldid' => $this->mOldid,
 467                                                         'rc_patrolled'  => 0
 468                                                 ),
 469                                                 __METHOD__
 470                                         );
 471                                         if ( $change instanceof RecentChange ) {
 472                                                 $rcid = $change->mAttribs['rc_id'];
 473                                                 $this->mRcidMarkPatrolled = $rcid;
 474                                         } else {
 475                                                 // None found
 476                                                 $rcid = 0;
 477                                         }
 478                                 }
 479                                 // Build the link
 480                                 if ( $rcid ) {
 481                                         $this->getOutput()->preventClickjacking();
 482                                         $this->getOutput()->addModules( 'mediawiki.page.patrol.ajax' );
 483
 484                                         $token = $this->getUser()->getEditToken( $rcid );
 485                                         $this->mMarkPatrolledLink = ' <span class="patrollink">[' . Linker::linkKnown(
 486                                                 $this->mNewPage,
 487                                                 $this->msg( 'markaspatrolleddiff' )->escaped(),
 488                                                 array(),
 489                                                 array(
 490                                                         'action' => 'markpatrolled',
 491                                                         'rcid' => $rcid,
 492                                                         'token' => $token,
 493                                                 )
 494                                         ) . ']</span>';
 495                                 } else {
 496                                         $this->mMarkPatrolledLink = '';
 497                                 }
 498                         } else {
 499                                 $this->mMarkPatrolledLink = '';
 500                         }
 501                 }
 502
 503                 return $this->mMarkPatrolledLink;
 504         }
 505
 506         /**
 507          * @param $rev Revision
 508          * @return String
 509          */
 510         protected function revisionDeleteLink( $rev ) {
 511                 $link = Linker::getRevDeleteLink( $this->getUser(), $rev, $rev->getTitle() );
 512                 if ( $link !== '' ) {
 513                         $link = '&#160;&#160;&#160;' . $link . ' ';
 514                 }
 515                 return $link;
 516         }
 517
 518         /**
 519          * Show the new revision of the page.
 520          */
 521         function renderNewRevision() {
 522                 wfProfileIn( __METHOD__ );
 523                 $out = $this->getOutput();
 524                 $revHeader = $this->getRevisionHeader( $this->mNewRev );
 525                 # Add "current version as of X" title
 526                 $out->addHTML( "<hr class='diff-hr' />
 527                 <h2 class='diff-currentversion-title'>{$revHeader}</h2>\n" );
 528                 # Page content may be handled by a hooked call instead...
 529                 if ( wfRunHooks( 'ArticleContentOnDiff', array( $this, $out ) ) ) {
 530                         $this->loadNewText();
 531                         $out->setRevisionId( $this->mNewid );
 532                         $out->setRevisionTimestamp( $this->mNewRev->getTimestamp() );
 533                         $out->setArticleFlag( true );
 534
 535                         // NOTE: only needed for B/C: custom rendering of JS/CSS via hook
 536                         if ( $this->mNewPage->isCssJsSubpage() || $this->mNewPage->isCssOrJsPage() ) {
 537                                 // Stolen from Article::view --AG 2007-10-11
 538                                 // Give hooks a chance to customise the output
 539                                 // @TODO: standardize this crap into one function
 540                                 if ( ContentHandler::runLegacyHooks( 'ShowRawCssJs', array( $this->mNewContent, $this->mNewPage, $out ) ) ) {
 541                                         // NOTE: deprecated hook, B/C only
 542                                         // use the content object's own rendering
 543                                         $cnt = $this->mNewRev->getContent();
 544                                         $po = $cnt ? $cnt->getParserOutput( $this->mNewRev->getTitle(), $this->mNewRev->getId() ) : null;
 545                                         $txt = $po ? $po->getText() : '';
 546                                         $out->addHTML( $txt );
 547                                 }
 548                         } elseif( !wfRunHooks( 'ArticleContentViewCustom', array( $this->mNewContent, $this->mNewPage, $out ) ) ) {
 549                                 // Handled by extension
 550                         } elseif( !ContentHandler::runLegacyHooks( 'ArticleViewCustom', array( $this->mNewContent, $this->mNewPage, $out ) ) ) {
 551                                 // NOTE: deprecated hook, B/C only
 552                                 // Handled by extension
 553                         } else {
 554                                 // Normal page
 555                                 if ( $this->getTitle()->equals( $this->mNewPage ) ) {
 556                                         // If the Title stored in the context is the same as the one
 557                                         // of the new revision, we can use its associated WikiPage
 558                                         // object.
 559                                         $wikiPage = $this->getWikiPage();
 560                                 } else {
 561                                         // Otherwise we need to create our own WikiPage object
 562                                         $wikiPage = WikiPage::factory( $this->mNewPage );
 563                                 }
 564
 565                                 $parserOutput = $this->getParserOutput( $wikiPage, $this->mNewRev );
 566
 567                                 # Also try to load it as a redirect
 568                                 $rt = $this->mNewContent ? $this->mNewContent->getRedirectTarget() : null;
 569
 570                                 if ( $rt ) {
 571                                         $article = Article::newFromTitle( $this->mNewPage, $this->getContext() );
 572                                         $out->addHTML( $article->viewRedirect( $rt ) );
 573
 574                                         # WikiPage::getParserOutput() should not return false, but just in case
 575                                         if ( $parserOutput ) {
 576                                                 # Show categories etc.
 577                                                 $out->addParserOutputNoText( $parserOutput );
 578                                         }
 579                                 } else if ( $parserOutput ) {
 580                                         $out->addParserOutput( $parserOutput );
 581                                 }
 582                         }
 583                 }
 584                 # Add redundant patrol link on bottom...
 585                 $out->addHTML( $this->markPatrolledLink() );
 586
 587                 wfProfileOut( __METHOD__ );
 588         }
 589
 590         protected function getParserOutput( WikiPage $page, Revision $rev ) {
 591                 $parserOptions = $page->makeParserOptions( $this->getContext() );
 592
 593                 if ( !$rev->isCurrent() || !$rev->getTitle()->quickUserCan( "edit" ) ) {
 594                         $parserOptions->setEditSection( false );
 595                 }
 596
 597                 $parserOutput = $page->getParserOutput( $parserOptions, $rev->getId() );
 598                 return $parserOutput;
 599         }
 600
 601         /**
 602          * Get the diff text, send it to the OutputPage object
 603          * Returns false if the diff could not be generated, otherwise returns true
 604          *
 605          * @return bool
 606          */
 607         function showDiff( $otitle, $ntitle, $notice = '' ) {
 608                 $diff = $this->getDiff( $otitle, $ntitle, $notice );
 609                 if ( $diff === false ) {
 610                         $this->showMissingRevision();
 611                         return false;
 612                 } else {
 613                         $this->showDiffStyle();
 614                         $this->getOutput()->addHTML( $diff );
 615                         return true;
 616                 }
 617         }
 618
 619         /**
 620          * Add style sheets and supporting JS for diff display.
 621          */
 622         function showDiffStyle() {
 623                 $this->getOutput()->addModuleStyles( 'mediawiki.action.history.diff' );
 624         }
 625
 626         /**
 627          * Get complete diff table, including header
 628          *
 629          * @param string|bool $otitle Header for old text or false
 630          * @param string|bool $ntitle Header for new text or false
 631          * @param string $notice HTML between diff header and body
 632          * @return mixed
 633          */
 634         function getDiff( $otitle, $ntitle, $notice = '' ) {
 635                 $body = $this->getDiffBody();
 636                 if ( $body === false ) {
 637                         return false;
 638                 } else {
 639                         $multi = $this->getMultiNotice();
 640                         return $this->addHeader( $body, $otitle, $ntitle, $multi, $notice );
 641                 }
 642         }
 643
 644         /**
 645          * Get the diff table body, without header
 646          *
 647          * @return mixed (string/false)
 648          */
 649         public function getDiffBody() {
 650                 global $wgMemc;
 651                 wfProfileIn( __METHOD__ );
 652                 $this->mCacheHit = true;
 653                 // Check if the diff should be hidden from this user
 654                 if ( !$this->loadRevisionData() ) {
 655                         wfProfileOut( __METHOD__ );
 656                         return false;
 657                 } elseif ( $this->mOldRev && !$this->mOldRev->userCan( Revision::DELETED_TEXT, $this->getUser() ) ) {
 658                         wfProfileOut( __METHOD__ );
 659                         return false;
 660                 } elseif ( $this->mNewRev && !$this->mNewRev->userCan( Revision::DELETED_TEXT, $this->getUser() ) ) {
 661                         wfProfileOut( __METHOD__ );
 662                         return false;
 663                 }
 664                 // Short-circuit
 665                 // If mOldRev is false, it means that the
 666                 if ( $this->mOldRev === false || ( $this->mOldRev && $this->mNewRev
 667                         && $this->mOldRev->getID() == $this->mNewRev->getID() ) )
 668                 {
 669                         wfProfileOut( __METHOD__ );
 670                         return '';
 671                 }
 672                 // Cacheable?
 673                 $key = false;
 674                 if ( $this->mOldid && $this->mNewid ) {
 675                         $key = wfMemcKey( 'diff', 'version', MW_DIFF_VERSION,
 676                                 'oldid', $this->mOldid, 'newid', $this->mNewid );
 677                         // Try cache
 678                         if ( !$this->mRefreshCache ) {
 679                                 $difftext = $wgMemc->get( $key );
 680                                 if ( $difftext ) {
 681                                         wfIncrStats( 'diff_cache_hit' );
 682                                         $difftext = $this->localiseLineNumbers( $difftext );
 683                                         $difftext .= "\n<!-- diff cache key $key -->\n";
 684                                         wfProfileOut( __METHOD__ );
 685                                         return $difftext;
 686                                 }
 687                         } // don't try to load but save the result
 688                 }
 689                 $this->mCacheHit = false;
 690
 691                 // Loadtext is permission safe, this just clears out the diff
 692                 if ( !$this->loadText() ) {
 693                         wfProfileOut( __METHOD__ );
 694                         return false;
 695                 }
 696
 697                 $difftext = $this->generateContentDiffBody( $this->mOldContent, $this->mNewContent );
 698
 699                 // Save to cache for 7 days
 700                 if ( !wfRunHooks( 'AbortDiffCache', array( &$this ) ) ) {
 701                         wfIncrStats( 'diff_uncacheable' );
 702                 } elseif ( $key !== false && $difftext !== false ) {
 703                         wfIncrStats( 'diff_cache_miss' );
 704                         $wgMemc->set( $key, $difftext, 7 * 86400 );
 705                 } else {
 706                         wfIncrStats( 'diff_uncacheable' );
 707                 }
 708                 // Replace line numbers with the text in the user's language
 709                 if ( $difftext !== false ) {
 710                         $difftext = $this->localiseLineNumbers( $difftext );
 711                 }
 712                 wfProfileOut( __METHOD__ );
 713                 return $difftext;
 714         }
 715
 716         /**
 717          * Make sure the proper modules are loaded before we try to
 718          * make the diff
 719          */
 720         private function initDiffEngines() {
 721                 global $wgExternalDiffEngine;
 722                 if ( $wgExternalDiffEngine == 'wikidiff' && !function_exists( 'wikidiff_do_diff' ) ) {
 723                         wfProfileIn( __METHOD__ . '-php_wikidiff.so' );
 724                         wfDl( 'php_wikidiff' );
 725                         wfProfileOut( __METHOD__ . '-php_wikidiff.so' );
 726                 }
 727                 elseif ( $wgExternalDiffEngine == 'wikidiff2' && !function_exists( 'wikidiff2_do_diff' ) ) {
 728                         wfProfileIn( __METHOD__ . '-php_wikidiff2.so' );
 729                         wfDl( 'wikidiff2' );
 730                         wfProfileOut( __METHOD__ . '-php_wikidiff2.so' );
 731                 }
 732         }
 733
 734         /**
 735          * Generate a diff, no caching.
 736          *
 737          * This implementation uses generateTextDiffBody() to generate a diff based on the default
 738          * serialization of the given Content objects. This will fail if $old or $new are not
 739          * instances of TextContent.
 740          *
 741          * Subclasses may override this to provide a different rendering for the diff,
 742          * perhaps taking advantage of the content's native form. This is required for all content
 743          * models that are not text based.
 744          *
 745          * @param $old Content: old content
 746          * @param $new Content: new content
 747          *
 748          * @return bool|string
 749          * @since 1.21
 750          * @throws MWException if $old or $new are not instances of TextContent.
 751          */
 752         function generateContentDiffBody( Content $old, Content $new ) {
 753                 if ( !( $old instanceof TextContent ) ) {
 754                         throw new MWException( "Diff not implemented for " . get_class( $old ) . "; "
 755                                         . "override generateContentDiffBody to fix this." );
 756                 }
 757
 758                 if ( !( $new instanceof TextContent ) ) {
 759                         throw new MWException( "Diff not implemented for " . get_class( $new ) . "; "
 760                                 . "override generateContentDiffBody to fix this." );
 761                 }
 762
 763                 $otext = $old->serialize();
 764                 $ntext = $new->serialize();
 765
 766                 return $this->generateTextDiffBody( $otext, $ntext );
 767         }
 768
 769         /**
 770          * Generate a diff, no caching
 771          *
 772          * @param string $otext old text, must be already segmented
 773          * @param string $ntext new text, must be already segmented
 774          * @return bool|string
 775          * @deprecated since 1.21, use generateContentDiffBody() instead!
 776          */
 777         function generateDiffBody( $otext, $ntext ) {
 778                 ContentHandler::deprecated( __METHOD__, "1.21" );
 779
 780                 return $this->generateTextDiffBody( $otext, $ntext );
 781         }
 782
 783         /**
 784          * Generate a diff, no caching
 785          *
 786          * @todo move this to TextDifferenceEngine, make DifferenceEngine abstract. At some point.
 787          *
 788          * @param string $otext old text, must be already segmented
 789          * @param string $ntext new text, must be already segmented
 790          * @return bool|string
 791          */
 792         function generateTextDiffBody( $otext, $ntext ) {
 793                 global $wgExternalDiffEngine, $wgContLang;
 794
 795                 wfProfileIn( __METHOD__ );
 796
 797                 $otext = str_replace( "\r\n", "\n", $otext );
 798                 $ntext = str_replace( "\r\n", "\n", $ntext );
 799
 800                 $this->initDiffEngines();
 801
 802                 if ( $wgExternalDiffEngine == 'wikidiff' && function_exists( 'wikidiff_do_diff' ) ) {
 803                         # For historical reasons, external diff engine expects
 804                         # input text to be HTML-escaped already
 805                         $otext = htmlspecialchars ( $wgContLang->segmentForDiff( $otext ) );
 806                         $ntext = htmlspecialchars ( $wgContLang->segmentForDiff( $ntext ) );
 807                         wfProfileOut( __METHOD__ );
 808                         return $wgContLang->unsegmentForDiff( wikidiff_do_diff( $otext, $ntext, 2 ) ) .
 809                         $this->debug( 'wikidiff1' );
 810                 }
 811
 812                 if ( $wgExternalDiffEngine == 'wikidiff2' && function_exists( 'wikidiff2_do_diff' ) ) {
 813                         # Better external diff engine, the 2 may some day be dropped
 814                         # This one does the escaping and segmenting itself
 815                         wfProfileIn( 'wikidiff2_do_diff' );
 816                         $text = wikidiff2_do_diff( $otext, $ntext, 2 );
 817                         $text .= $this->debug( 'wikidiff2' );
 818                         wfProfileOut( 'wikidiff2_do_diff' );
 819                         wfProfileOut( __METHOD__ );
 820                         return $text;
 821                 }
 822                 if ( $wgExternalDiffEngine != 'wikidiff3' && $wgExternalDiffEngine !== false ) {
 823                         # Diff via the shell
 824                         $tmpDir = wfTempDir();
 825                         $tempName1 = tempnam( $tmpDir, 'diff_' );
 826                         $tempName2 = tempnam( $tmpDir, 'diff_' );
 827
 828                         $tempFile1 = fopen( $tempName1, "w" );
 829                         if ( !$tempFile1 ) {
 830                                 wfProfileOut( __METHOD__ );
 831                                 return false;
 832                         }
 833                         $tempFile2 = fopen( $tempName2, "w" );
 834                         if ( !$tempFile2 ) {
 835                                 wfProfileOut( __METHOD__ );
 836                                 return false;
 837                         }
 838                         fwrite( $tempFile1, $otext );
 839                         fwrite( $tempFile2, $ntext );
 840                         fclose( $tempFile1 );
 841                         fclose( $tempFile2 );
 842                         $cmd = wfEscapeShellArg( $wgExternalDiffEngine, $tempName1, $tempName2 );
 843                         wfProfileIn( __METHOD__ . "-shellexec" );
 844                         $difftext = wfShellExec( $cmd );
 845                         $difftext .= $this->debug( "external $wgExternalDiffEngine" );
 846                         wfProfileOut( __METHOD__ . "-shellexec" );
 847                         unlink( $tempName1 );
 848                         unlink( $tempName2 );
 849                         wfProfileOut( __METHOD__ );
 850                         return $difftext;
 851                 }
 852
 853                 # Native PHP diff
 854                 $ota = explode( "\n", $wgContLang->segmentForDiff( $otext ) );
 855                 $nta = explode( "\n", $wgContLang->segmentForDiff( $ntext ) );
 856                 $diffs = new Diff( $ota, $nta );
 857                 $formatter = new TableDiffFormatter();
 858                 $difftext = $wgContLang->unsegmentForDiff( $formatter->format( $diffs ) ) .
 859                 wfProfileOut( __METHOD__ );
 860                 return $difftext;
 861         }
 862
 863         /**
 864          * Generate a debug comment indicating diff generating time,
 865          * server node, and generator backend.
 866          * @return string
 867          */
 868         protected function debug( $generator = "internal" ) {
 869                 global $wgShowHostnames;
 870                 if ( !$this->enableDebugComment ) {
 871                         return '';
 872                 }
 873                 $data = array( $generator );
 874                 if ( $wgShowHostnames ) {
 875                         $data[] = wfHostname();
 876                 }
 877                 $data[] = wfTimestamp( TS_DB );
 878                 return "<!-- diff generator: " .
 879                 implode( " ",
 880                 array_map(
 881                                         "htmlspecialchars",
 882                 $data ) ) .
 883                         " -->\n";
 884         }
 885
 886         /**
 887          * Replace line numbers with the text in the user's language
 888          * @return mixed
 889          */
 890         function localiseLineNumbers( $text ) {
 891                 return preg_replace_callback( '/<!--LINE (\d+)-->/',
 892                 array( &$this, 'localiseLineNumbersCb' ), $text );
 893         }
 894
 895         function localiseLineNumbersCb( $matches ) {
 896                 if ( $matches[1] === '1' && $this->mReducedLineNumbers ) return '';
 897                 return $this->msg( 'lineno' )->numParams( $matches[1] )->escaped();
 898         }
 899
 900         /**
 901          * If there are revisions between the ones being compared, return a note saying so.
 902          * @return string
 903          */
 904         function getMultiNotice() {
 905                 if ( !is_object( $this->mOldRev ) || !is_object( $this->mNewRev ) ) {
 906                         return '';
 907                 } elseif ( !$this->mOldPage->equals( $this->mNewPage ) ) {
 908                         // Comparing two different pages? Count would be meaningless.
 909                         return '';
 910                 }
 911
 912                 if ( $this->mOldRev->getTimestamp() > $this->mNewRev->getTimestamp() ) {
 913                         $oldRev = $this->mNewRev; // flip
 914                         $newRev = $this->mOldRev; // flip
 915                 } else { // normal case
 916                         $oldRev = $this->mOldRev;
 917                         $newRev = $this->mNewRev;
 918                 }
 919
 920                 $nEdits = $this->mNewPage->countRevisionsBetween( $oldRev, $newRev );
 921                 if ( $nEdits > 0 ) {
 922                         $limit = 100; // use diff-multi-manyusers if too many users
 923                         $numUsers = $this->mNewPage->countAuthorsBetween( $oldRev, $newRev, $limit );
 924                         return self::intermediateEditsMsg( $nEdits, $numUsers, $limit );
 925                 }
 926                 return ''; // nothing
 927         }
 928
 929         /**
 930          * Get a notice about how many intermediate edits and users there are
 931          * @param $numEdits int
 932          * @param $numUsers int
 933          * @param $limit int
 934          * @return string
 935          */
 936         public static function intermediateEditsMsg( $numEdits, $numUsers, $limit ) {
 937                 if ( $numUsers > $limit ) {
 938                         $msg = 'diff-multi-manyusers';
 939                         $numUsers = $limit;
 940                 } else {
 941                         $msg = 'diff-multi';
 942                 }
 943                 return wfMessage( $msg )->numParams( $numEdits, $numUsers )->parse();
 944         }
 945
 946         /**
 947          * Get a header for a specified revision.
 948          *
 949          * @param $rev Revision
 950          * @param string $complete 'complete' to get the header wrapped depending
 951          *        the visibility of the revision and a link to edit the page.
 952          * @return String HTML fragment
 953          */
 954         protected function getRevisionHeader( Revision $rev, $complete = '' ) {
 955                 $lang = $this->getLanguage();
 956                 $user = $this->getUser();
 957                 $revtimestamp = $rev->getTimestamp();
 958                 $timestamp = $lang->userTimeAndDate( $revtimestamp, $user );
 959                 $dateofrev = $lang->userDate( $revtimestamp, $user );
 960                 $timeofrev = $lang->userTime( $revtimestamp, $user );
 961
 962                 $header = $this->msg(
 963                         $rev->isCurrent() ? 'currentrev-asof' : 'revisionasof',
 964                         $timestamp,
 965                         $dateofrev,
 966                         $timeofrev
 967                 )->escaped();
 968
 969                 if ( $complete !== 'complete' ) {
 970                         return $header;
 971                 }
 972
 973                 $title = $rev->getTitle();
 974
 975                 $header = Linker::linkKnown( $title, $header, array(),
 976                         array( 'oldid' => $rev->getID() ) );
 977
 978                 if ( $rev->userCan( Revision::DELETED_TEXT, $user ) ) {
 979                         $editQuery = array( 'action' => 'edit' );
 980                         if ( !$rev->isCurrent() ) {
 981                                 $editQuery['oldid'] = $rev->getID();
 982                         }
 983
 984                         $msg = $this->msg( $title->quickUserCan( 'edit', $user ) ? 'editold' : 'viewsourceold' )->escaped();
 985                         $header .= ' ' . $this->msg( 'parentheses' )->rawParams(
 986                                 Linker::linkKnown( $title, $msg, array(), $editQuery ) )->plain();
 987                         if ( $rev->isDeleted( Revision::DELETED_TEXT ) ) {
 988                                 $header = Html::rawElement( 'span', array( 'class' => 'history-deleted' ), $header );
 989                         }
 990                 } else {
 991                         $header = Html::rawElement( 'span', array( 'class' => 'history-deleted' ), $header );
 992                 }
 993
 994                 return $header;
 995         }
 996
 997         /**
 998          * Add the header to a diff body
 999          *
1000          * @return string
1001          */
1002         function addHeader( $diff, $otitle, $ntitle, $multi = '', $notice = '' ) {
1003                 // shared.css sets diff in interface language/dir, but the actual content
1004                 // is often in a different language, mostly the page content language/dir
1005                 $tableClass = 'diff diff-contentalign-' . htmlspecialchars( $this->getDiffLang()->alignStart() );
1006                 $header = "<table class='$tableClass'>";
1007
1008                 if ( !$diff && !$otitle ) {
1009                         $header .= "
1010                         <tr style='vertical-align: top;'>
1011                         <td class='diff-ntitle'>{$ntitle}</td>
1012                         </tr>";
1013                         $multiColspan = 1;
1014                 } else {
1015                         if ( $diff ) { // Safari/Chrome show broken output if cols not used
1016                                 $header .= "
1017                                 <col class='diff-marker' />
1018                                 <col class='diff-content' />
1019                                 <col class='diff-marker' />
1020                                 <col class='diff-content' />";
1021                                 $colspan = 2;
1022                                 $multiColspan = 4;
1023                         } else {
1024                                 $colspan = 1;
1025                                 $multiColspan = 2;
1026                         }
1027                         $header .= "
1028                         <tr style='vertical-align: top;'>
1029                         <td colspan='$colspan' class='diff-otitle'>{$otitle}</td>
1030                         <td colspan='$colspan' class='diff-ntitle'>{$ntitle}</td>
1031                         </tr>";
1032                 }
1033
1034                 if ( $multi != '' ) {
1035                         $header .= "<tr><td colspan='{$multiColspan}' style='text-align: center;' class='diff-multi'>{$multi}</td></tr>";
1036                 }
1037                 if ( $notice != '' ) {
1038                         $header .= "<tr><td colspan='{$multiColspan}' style='text-align: center;'>{$notice}</td></tr>";
1039                 }
1040
1041                 return $header . $diff . "</table>";
1042         }
1043
1044         /**
1045          * Use specified text instead of loading from the database
1046          * @deprecated since 1.21, use setContent() instead.
1047          */
1048         function setText( $oldText, $newText ) {
1049                 ContentHandler::deprecated( __METHOD__, "1.21" );
1050
1051                 $oldContent = ContentHandler::makeContent( $oldText, $this->getTitle() );
1052                 $newContent = ContentHandler::makeContent( $newText, $this->getTitle() );
1053
1054                 $this->setContent( $oldContent, $newContent );
1055         }
1056
1057         /**
1058          * Use specified text instead of loading from the database
1059          * @since 1.21
1060          */
1061         function setContent( Content $oldContent, Content $newContent ) {
1062                 $this->mOldContent = $oldContent;
1063                 $this->mNewContent = $newContent;
1064
1065                 $this->mTextLoaded = 2;
1066                 $this->mRevisionsLoaded = true;
1067         }
1068
1069         /**
1070          * Set the language in which the diff text is written
1071          * (Defaults to page content language).
1072          * @since 1.19
1073          */
1074         function setTextLanguage( $lang ) {
1075                 $this->mDiffLang = wfGetLangObj( $lang );
1076         }
1077
1078         /**
1079          * Load revision IDs
1080          */
1081         private function loadRevisionIds() {
1082                 if ( $this->mRevisionsIdsLoaded ) {
1083                         return;
1084                 }
1085
1086                 $this->mRevisionsIdsLoaded = true;
1087
1088                 $old = $this->mOldid;
1089                 $new = $this->mNewid;
1090
1091                 if ( $new === 'prev' ) {
1092                         # Show diff between revision $old and the previous one.
1093                         # Get previous one from DB.
1094                         $this->mNewid = intval( $old );
1095                         $this->mOldid = $this->getTitle()->getPreviousRevisionID( $this->mNewid );
1096                 } elseif ( $new === 'next' ) {
1097                         # Show diff between revision $old and the next one.
1098                         # Get next one from DB.
1099                         $this->mOldid = intval( $old );
1100                         $this->mNewid = $this->getTitle()->getNextRevisionID( $this->mOldid );
1101                         if ( $this->mNewid === false ) {
1102                                 # if no result, NewId points to the newest old revision. The only newer
1103                                 # revision is cur, which is "0".
1104                                 $this->mNewid = 0;
1105                         }
1106                 } else {
1107                         $this->mOldid = intval( $old );
1108                         $this->mNewid = intval( $new );
1109                         wfRunHooks( 'NewDifferenceEngine', array( $this->getTitle(), &$this->mOldid, &$this->mNewid, $old, $new ) );
1110                 }
1111         }
1112
1113         /**
1114          * Load revision metadata for the specified articles. If newid is 0, then compare
1115          * the old article in oldid to the current article; if oldid is 0, then
1116          * compare the current article to the immediately previous one (ignoring the
1117          * value of newid).
1118          *
1119          * If oldid is false, leave the corresponding revision object set
1120          * to false. This is impossible via ordinary user input, and is provided for
1121          * API convenience.
1122          *
1123          * @return bool
1124          */
1125         function loadRevisionData() {
1126                 if ( $this->mRevisionsLoaded ) {
1127                         return true;
1128                 }
1129
1130                 // Whether it succeeds or fails, we don't want to try again
1131                 $this->mRevisionsLoaded = true;
1132
1133                 $this->loadRevisionIds();
1134
1135                 // Load the new revision object
1136                 $this->mNewRev = $this->mNewid
1137                         ? Revision::newFromId( $this->mNewid )
1138                         : Revision::newFromTitle( $this->getTitle(), false, Revision::READ_NORMAL );
1139
1140                 if ( !$this->mNewRev instanceof Revision ) {
1141                         return false;
1142                 }
1143
1144                 // Update the new revision ID in case it was 0 (makes life easier doing UI stuff)
1145                 $this->mNewid = $this->mNewRev->getId();
1146                 $this->mNewPage = $this->mNewRev->getTitle();
1147
1148                 // Load the old revision object
1149                 $this->mOldRev = false;
1150                 if ( $this->mOldid ) {
1151                         $this->mOldRev = Revision::newFromId( $this->mOldid );
1152                 } elseif ( $this->mOldid === 0 ) {
1153                         $rev = $this->mNewRev->getPrevious();
1154                         if ( $rev ) {
1155                                 $this->mOldid = $rev->getId();
1156                                 $this->mOldRev = $rev;
1157                         } else {
1158                                 // No previous revision; mark to show as first-version only.
1159                                 $this->mOldid = false;
1160                                 $this->mOldRev = false;
1161                         }
1162                 } /* elseif ( $this->mOldid === false ) leave mOldRev false; */
1163
1164                 if ( is_null( $this->mOldRev ) ) {
1165                         return false;
1166                 }
1167
1168                 if ( $this->mOldRev ) {
1169                         $this->mOldPage = $this->mOldRev->getTitle();
1170                 }
1171
1172                 return true;
1173         }
1174
1175         /**
1176          * Load the text of the revisions, as well as revision data.
1177          *
1178          * @return bool
1179          */
1180         function loadText() {
1181                 if ( $this->mTextLoaded == 2 ) {
1182                         return true;
1183                 } else {
1184                         // Whether it succeeds or fails, we don't want to try again
1185                         $this->mTextLoaded = 2;
1186                 }
1187
1188                 if ( !$this->loadRevisionData() ) {
1189                         return false;
1190                 }
1191                 if ( $this->mOldRev ) {
1192                         $this->mOldContent = $this->mOldRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1193                         if ( $this->mOldContent === null ) {
1194                                 return false;
1195                         }
1196                 }
1197                 if ( $this->mNewRev ) {
1198                         $this->mNewContent = $this->mNewRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1199                         if ( $this->mNewContent === null ) {
1200                                 return false;
1201                         }
1202                 }
1203                 return true;
1204         }
1205
1206         /**
1207          * Load the text of the new revision, not the old one
1208          *
1209          * @return bool
1210          */
1211         function loadNewText() {
1212                 if ( $this->mTextLoaded >= 1 ) {
1213                         return true;
1214                 } else {
1215                         $this->mTextLoaded = 1;
1216                 }
1217                 if ( !$this->loadRevisionData() ) {
1218                         return false;
1219                 }
1220                 $this->mNewContent = $this->mNewRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1221                 return true;
1222         }
1223 }