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