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