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         /** @var int */
  39         public $mOldid;
  40
  41         /** @var int */
  42         public $mNewid;
  43
  44         private $mOldTags;
  45         private $mNewTags;
  46
  47         /** @var Content */
  48         public $mOldContent;
  49
  50         /** @var Content */
  51         public $mNewContent;
  52
  53         /** @var Language */
  54         protected $mDiffLang;
  55
  56         /** @var Title */
  57         public $mOldPage;
  58
  59         /** @var Title */
  60         public $mNewPage;
  61
  62         /** @var Revision */
  63         public $mOldRev;
  64
  65         /** @var Revision */
  66         public $mNewRev;
  67
  68         /** @var bool Have the revisions IDs been loaded */
  69         private $mRevisionsIdsLoaded = false;
  70
  71         /** @var bool Have the revisions been loaded */
  72         public $mRevisionsLoaded = false;
  73
  74         /** @var int How many text blobs have been loaded, 0, 1 or 2? */
  75         public $mTextLoaded = 0;
  76
  77         /** @var bool Was the diff fetched from cache? */
  78         public $mCacheHit = false;
  79
  80         /**
  81          * Set this to true to add debug info to the HTML output.
  82          * Warning: this may cause RSS readers to spuriously mark articles as "new"
  83          * (bug 20601)
  84          */
  85         public $enableDebugComment = false;
  86
  87         /** @var bool If true, line X is not displayed when X is 1, for example
  88          *    to increase readability and conserve space with many small diffs.
  89          */
  90         protected $mReducedLineNumbers = false;
  91
  92         /** @var string Link to action=markpatrolled */
  93         protected $mMarkPatrolledLink = null;
  94
  95         /** @var bool Show rev_deleted content if allowed */
  96         protected $unhide = false;
  97         /**#@-*/
  98
  99         /**
 100          * Constructor
 101          * @param IContextSource $context Context to use, anything else will be ignored
 102          * @param int $old Old ID we want to show and diff with.
 103          * @param string|int $new Either revision ID or 'prev' or 'next'. Default: 0.
 104          * @param int $rcid Deprecated, no longer used!
 105          * @param bool $refreshCache If set, refreshes the diff cache
 106          * @param bool $unhide If set, allow viewing deleted revs
 107          */
 108         public function __construct( $context = null, $old = 0, $new = 0, $rcid = 0,
 109                 $refreshCache = false, $unhide = false
 110         ) {
 111                 if ( $context instanceof IContextSource ) {
 112                         $this->setContext( $context );
 113                 }
 114
 115                 wfDebug( "DifferenceEngine old '$old' new '$new' rcid '$rcid'\n" );
 116
 117                 $this->mOldid = $old;
 118                 $this->mNewid = $new;
 119                 $this->mRefreshCache = $refreshCache;
 120                 $this->unhide = $unhide;
 121         }
 122
 123         /**
 124          * @param bool $value
 125          */
 126         public function setReducedLineNumbers( $value = true ) {
 127                 $this->mReducedLineNumbers = $value;
 128         }
 129
 130         /**
 131          * @return Language
 132          */
 133         public function getDiffLang() {
 134                 if ( $this->mDiffLang === null ) {
 135                         # Default language in which the diff text is written.
 136                         $this->mDiffLang = $this->getTitle()->getPageLanguage();
 137                 }
 138
 139                 return $this->mDiffLang;
 140         }
 141
 142         /**
 143          * @return bool
 144          */
 145         public function wasCacheHit() {
 146                 return $this->mCacheHit;
 147         }
 148
 149         /**
 150          * @return int
 151          */
 152         public function getOldid() {
 153                 $this->loadRevisionIds();
 154
 155                 return $this->mOldid;
 156         }
 157
 158         /**
 159          * @return bool|int
 160          */
 161         public function getNewid() {
 162                 $this->loadRevisionIds();
 163
 164                 return $this->mNewid;
 165         }
 166
 167         /**
 168          * Look up a special:Undelete link to the given deleted revision id,
 169          * as a workaround for being unable to load deleted diffs in currently.
 170          *
 171          * @param int $id Revision ID
 172          *
 173          * @return mixed URL or false
 174          */
 175         public function deletedLink( $id ) {
 176                 if ( $this->getUser()->isAllowed( 'deletedhistory' ) ) {
 177                         $dbr = wfGetDB( DB_SLAVE );
 178                         $row = $dbr->selectRow( 'archive', '*',
 179                                 array( 'ar_rev_id' => $id ),
 180                                 __METHOD__ );
 181                         if ( $row ) {
 182                                 $rev = Revision::newFromArchiveRow( $row );
 183                                 $title = Title::makeTitleSafe( $row->ar_namespace, $row->ar_title );
 184
 185                                 return SpecialPage::getTitleFor( 'Undelete' )->getFullURL( array(
 186                                         'target' => $title->getPrefixedText(),
 187                                         'timestamp' => $rev->getTimestamp()
 188                                 ) );
 189                         }
 190                 }
 191
 192                 return false;
 193         }
 194
 195         /**
 196          * Build a wikitext link toward a deleted revision, if viewable.
 197          *
 198          * @param int $id Revision ID
 199          *
 200          * @return string Wikitext fragment
 201          */
 202         public function deletedIdMarker( $id ) {
 203                 $link = $this->deletedLink( $id );
 204                 if ( $link ) {
 205                         return "[$link $id]";
 206                 } else {
 207                         return $id;
 208                 }
 209         }
 210
 211         private function showMissingRevision() {
 212                 $out = $this->getOutput();
 213
 214                 $missing = array();
 215                 if ( $this->mOldRev === null ||
 216                         ( $this->mOldRev && $this->mOldContent === null )
 217                 ) {
 218                         $missing[] = $this->deletedIdMarker( $this->mOldid );
 219                 }
 220                 if ( $this->mNewRev === null ||
 221                         ( $this->mNewRev && $this->mNewContent === null )
 222                 ) {
 223                         $missing[] = $this->deletedIdMarker( $this->mNewid );
 224                 }
 225
 226                 $out->setPageTitle( $this->msg( 'errorpagetitle' ) );
 227                 $msg = $this->msg( 'difference-missing-revision' )
 228                         ->params( $this->getLanguage()->listToText( $missing ) )
 229                         ->numParams( count( $missing ) )
 230                         ->parseAsBlock();
 231                 $out->addHtml( $msg );
 232         }
 233
 234         public function showDiffPage( $diffOnly = false ) {
 235
 236                 # Allow frames except in certain special cases
 237                 $out = $this->getOutput();
 238                 $out->allowClickjacking();
 239                 $out->setRobotPolicy( 'noindex,nofollow' );
 240
 241                 if ( !$this->loadRevisionData() ) {
 242                         $this->showMissingRevision();
 243
 244                         return;
 245                 }
 246
 247                 $user = $this->getUser();
 248                 $permErrors = $this->mNewPage->getUserPermissionsErrors( 'read', $user );
 249                 if ( $this->mOldPage ) { # mOldPage might not be set, see below.
 250                         $permErrors = wfMergeErrorArrays( $permErrors,
 251                                 $this->mOldPage->getUserPermissionsErrors( 'read', $user ) );
 252                 }
 253                 if ( count( $permErrors ) ) {
 254                         throw new PermissionsError( 'read', $permErrors );
 255                 }
 256
 257                 $rollback = '';
 258
 259                 $query = array();
 260                 # Carry over 'diffonly' param via navigation links
 261                 if ( $diffOnly != $user->getBoolOption( 'diffonly' ) ) {
 262                         $query['diffonly'] = $diffOnly;
 263                 }
 264                 # Cascade unhide param in links for easy deletion browsing
 265                 if ( $this->unhide ) {
 266                         $query['unhide'] = 1;
 267                 }
 268
 269                 # Check if one of the revisions is deleted/suppressed
 270                 $deleted = $suppressed = false;
 271                 $allowed = $this->mNewRev->userCan( Revision::DELETED_TEXT, $user );
 272
 273                 $revisionTools = array();
 274
 275                 # mOldRev is false if the difference engine is called with a "vague" query for
 276                 # a diff between a version V and its previous version V' AND the version V
 277                 # is the first version of that article. In that case, V' does not exist.
 278                 if ( $this->mOldRev === false ) {
 279                         $out->setPageTitle( $this->msg( 'difference-title', $this->mNewPage->getPrefixedText() ) );
 280                         $samePage = true;
 281                         $oldHeader = '';
 282                 } else {
 283                         Hooks::run( 'DiffViewHeader', array( $this, $this->mOldRev, $this->mNewRev ) );
 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',
 290                                         $this->mOldPage->getPrefixedText(), $this->mNewPage->getPrefixedText() ) );
 291                                 $out->addSubtitle( $this->msg( 'difference-multipage' ) );
 292                                 $samePage = false;
 293                         }
 294
 295                         if ( $samePage && $this->mNewPage->quickUserCan( 'edit', $user ) ) {
 296                                 if ( $this->mNewRev->isCurrent() && $this->mNewPage->userCan( 'rollback', $user ) ) {
 297                                         $rollbackLink = Linker::generateRollback( $this->mNewRev, $this->getContext() );
 298                                         if ( $rollbackLink ) {
 299                                                 $out->preventClickjacking();
 300                                                 $rollback = '&#160;&#160;&#160;' . $rollbackLink;
 301                                         }
 302                                 }
 303
 304                                 if ( !$this->mOldRev->isDeleted( Revision::DELETED_TEXT ) &&
 305                                         !$this->mNewRev->isDeleted( Revision::DELETED_TEXT )
 306                                 ) {
 307                                         $undoLink = Html::element( 'a', array(
 308                                                         'href' => $this->mNewPage->getLocalURL( array(
 309                                                                 'action' => 'edit',
 310                                                                 'undoafter' => $this->mOldid,
 311                                                                 'undo' => $this->mNewid
 312                                                         ) ),
 313                                                         'title' => Linker::titleAttrib( 'undo' ),
 314                                                 ),
 315                                                 $this->msg( 'editundo' )->text()
 316                                         );
 317                                         $revisionTools['mw-diff-undo'] = $undoLink;
 318                                 }
 319                         }
 320
 321                         # Make "previous revision link"
 322                         if ( $samePage && $this->mOldRev->getPrevious() ) {
 323                                 $prevlink = Linker::linkKnown(
 324                                         $this->mOldPage,
 325                                         $this->msg( 'previousdiff' )->escaped(),
 326                                         array( 'id' => 'differences-prevlink' ),
 327                                         array( 'diff' => 'prev', 'oldid' => $this->mOldid ) + $query
 328                                 );
 329                         } else {
 330                                 $prevlink = '&#160;';
 331                         }
 332
 333                         if ( $this->mOldRev->isMinor() ) {
 334                                 $oldminor = ChangesList::flag( 'minor' );
 335                         } else {
 336                                 $oldminor = '';
 337                         }
 338
 339                         $ldel = $this->revisionDeleteLink( $this->mOldRev );
 340                         $oldRevisionHeader = $this->getRevisionHeader( $this->mOldRev, 'complete' );
 341                         $oldChangeTags = ChangeTags::formatSummaryRow( $this->mOldTags, 'diff' );
 342
 343                         $oldHeader = '<div id="mw-diff-otitle1"><strong>' . $oldRevisionHeader . '</strong></div>' .
 344                                 '<div id="mw-diff-otitle2">' .
 345                                 Linker::revUserTools( $this->mOldRev, !$this->unhide ) . '</div>' .
 346                                 '<div id="mw-diff-otitle3">' . $oldminor .
 347                                 Linker::revComment( $this->mOldRev, !$diffOnly, !$this->unhide ) . $ldel . '</div>' .
 348                                 '<div id="mw-diff-otitle5">' . $oldChangeTags[0] . '</div>' .
 349                                 '<div id="mw-diff-otitle4">' . $prevlink . '</div>';
 350
 351                         if ( $this->mOldRev->isDeleted( Revision::DELETED_TEXT ) ) {
 352                                 $deleted = true; // old revisions text is hidden
 353                                 if ( $this->mOldRev->isDeleted( Revision::DELETED_RESTRICTED ) ) {
 354                                         $suppressed = true; // also suppressed
 355                                 }
 356                         }
 357
 358                         # Check if this user can see the revisions
 359                         if ( !$this->mOldRev->userCan( Revision::DELETED_TEXT, $user ) ) {
 360                                 $allowed = false;
 361                         }
 362                 }
 363
 364                 # Make "next revision link"
 365                 # Skip next link on the top revision
 366                 if ( $samePage && !$this->mNewRev->isCurrent() ) {
 367                         $nextlink = Linker::linkKnown(
 368                                 $this->mNewPage,
 369                                 $this->msg( 'nextdiff' )->escaped(),
 370                                 array( 'id' => 'differences-nextlink' ),
 371                                 array( 'diff' => 'next', 'oldid' => $this->mNewid ) + $query
 372                         );
 373                 } else {
 374                         $nextlink = '&#160;';
 375                 }
 376
 377                 if ( $this->mNewRev->isMinor() ) {
 378                         $newminor = ChangesList::flag( 'minor' );
 379                 } else {
 380                         $newminor = '';
 381                 }
 382
 383                 # Handle RevisionDelete links...
 384                 $rdel = $this->revisionDeleteLink( $this->mNewRev );
 385
 386                 # Allow extensions to define their own revision tools
 387                 Hooks::run( 'DiffRevisionTools', array( $this->mNewRev, &$revisionTools, $this->mOldRev ) );
 388                 $formattedRevisionTools = array();
 389                 // Put each one in parentheses (poor man's button)
 390                 foreach ( $revisionTools as $key => $tool ) {
 391                         $toolClass = is_string( $key ) ? $key : 'mw-diff-tool';
 392                         $element = Html::rawElement(
 393                                 'span',
 394                                 array( 'class' => $toolClass ),
 395                                 $this->msg( 'parentheses' )->rawParams( $tool )->escaped()
 396                         );
 397                         $formattedRevisionTools[] = $element;
 398                 }
 399                 $newRevisionHeader = $this->getRevisionHeader( $this->mNewRev, 'complete' ) .
 400                         ' ' . implode( ' ', $formattedRevisionTools );
 401                 $newChangeTags = ChangeTags::formatSummaryRow( $this->mNewTags, 'diff' );
 402
 403                 $newHeader = '<div id="mw-diff-ntitle1"><strong>' . $newRevisionHeader . '</strong></div>' .
 404                         '<div id="mw-diff-ntitle2">' . Linker::revUserTools( $this->mNewRev, !$this->unhide ) .
 405                         " $rollback</div>" .
 406                         '<div id="mw-diff-ntitle3">' . $newminor .
 407                         Linker::revComment( $this->mNewRev, !$diffOnly, !$this->unhide ) . $rdel . '</div>' .
 408                         '<div id="mw-diff-ntitle5">' . $newChangeTags[0] . '</div>' .
 409                         '<div id="mw-diff-ntitle4">' . $nextlink . $this->markPatrolledLink() . '</div>';
 410
 411                 if ( $this->mNewRev->isDeleted( Revision::DELETED_TEXT ) ) {
 412                         $deleted = true; // new revisions text is hidden
 413                         if ( $this->mNewRev->isDeleted( Revision::DELETED_RESTRICTED ) ) {
 414                                 $suppressed = true; // also suppressed
 415                         }
 416                 }
 417
 418                 # If the diff cannot be shown due to a deleted revision, then output
 419                 # the diff header and links to unhide (if available)...
 420                 if ( $deleted && ( !$this->unhide || !$allowed ) ) {
 421                         $this->showDiffStyle();
 422                         $multi = $this->getMultiNotice();
 423                         $out->addHTML( $this->addHeader( '', $oldHeader, $newHeader, $multi ) );
 424                         if ( !$allowed ) {
 425                                 $msg = $suppressed ? 'rev-suppressed-no-diff' : 'rev-deleted-no-diff';
 426                                 # Give explanation for why revision is not visible
 427                                 $out->wrapWikiMsg( "<div id='mw-$msg' class='mw-warning plainlinks'>\n$1\n</div>\n",
 428                                         array( $msg ) );
 429                         } else {
 430                                 # Give explanation and add a link to view the diff...
 431                                 $query = $this->getRequest()->appendQueryValue( 'unhide', '1', true );
 432                                 $link = $this->getTitle()->getFullURL( $query );
 433                                 $msg = $suppressed ? 'rev-suppressed-unhide-diff' : 'rev-deleted-unhide-diff';
 434                                 $out->wrapWikiMsg(
 435                                         "<div id='mw-$msg' class='mw-warning plainlinks'>\n$1\n</div>\n",
 436                                         array( $msg, $link )
 437                                 );
 438                         }
 439                 # Otherwise, output a regular diff...
 440                 } else {
 441                         # Add deletion notice if the user is viewing deleted content
 442                         $notice = '';
 443                         if ( $deleted ) {
 444                                 $msg = $suppressed ? 'rev-suppressed-diff-view' : 'rev-deleted-diff-view';
 445                                 $notice = "<div id='mw-$msg' class='mw-warning plainlinks'>\n" .
 446                                         $this->msg( $msg )->parse() .
 447                                         "</div>\n";
 448                         }
 449                         $this->showDiff( $oldHeader, $newHeader, $notice );
 450                         if ( !$diffOnly ) {
 451                                 $this->renderNewRevision();
 452                         }
 453                 }
 454         }
 455
 456         /**
 457          * Get a link to mark the change as patrolled, or '' if there's either no
 458          * revision to patrol or the user is not allowed to to it.
 459          * Side effect: When the patrol link is build, this method will call
 460          * OutputPage::preventClickjacking() and load mediawiki.page.patrol.ajax.
 461          *
 462          * @return string
 463          */
 464         protected function markPatrolledLink() {
 465                 global $wgUseRCPatrol, $wgEnableAPI, $wgEnableWriteAPI;
 466                 $user = $this->getUser();
 467
 468                 if ( $this->mMarkPatrolledLink === null ) {
 469                         // Prepare a change patrol link, if applicable
 470                         if (
 471                                 // Is patrolling enabled and the user allowed to?
 472                                 $wgUseRCPatrol && $this->mNewPage->quickUserCan( 'patrol', $user ) &&
 473                                 // Only do this if the revision isn't more than 6 hours older
 474                                 // than the Max RC age (6h because the RC might not be cleaned out regularly)
 475                                 RecentChange::isInRCLifespan( $this->mNewRev->getTimestamp(), 21600 )
 476                         ) {
 477                                 // Look for an unpatrolled change corresponding to this diff
 478
 479                                 $db = wfGetDB( DB_SLAVE );
 480                                 $change = RecentChange::newFromConds(
 481                                         array(
 482                                                 'rc_timestamp' => $db->timestamp( $this->mNewRev->getTimestamp() ),
 483                                                 'rc_this_oldid' => $this->mNewid,
 484                                                 'rc_patrolled' => 0
 485                                         ),
 486                                         __METHOD__,
 487                                         array( 'USE INDEX' => 'rc_timestamp' )
 488                                 );
 489
 490                                 if ( $change && $change->getPerformer()->getName() !== $user->getName() ) {
 491                                         $rcid = $change->getAttribute( 'rc_id' );
 492                                 } else {
 493                                         // None found or the page has been created by the current user.
 494                                         // If the user could patrol this it already would be patrolled
 495                                         $rcid = 0;
 496                                 }
 497                                 // Build the link
 498                                 if ( $rcid ) {
 499                                         $this->getOutput()->preventClickjacking();
 500                                         if ( $wgEnableAPI && $wgEnableWriteAPI
 501                                                 && $user->isAllowed( 'writeapi' )
 502                                         ) {
 503                                                 $this->getOutput()->addModules( 'mediawiki.page.patrol.ajax' );
 504                                         }
 505
 506                                         $token = $user->getEditToken( $rcid );
 507                                         $this->mMarkPatrolledLink = ' <span class="patrollink">[' . Linker::linkKnown(
 508                                                 $this->mNewPage,
 509                                                 $this->msg( 'markaspatrolleddiff' )->escaped(),
 510                                                 array(),
 511                                                 array(
 512                                                         'action' => 'markpatrolled',
 513                                                         'rcid' => $rcid,
 514                                                         'token' => $token,
 515                                                 )
 516                                         ) . ']</span>';
 517                                 } else {
 518                                         $this->mMarkPatrolledLink = '';
 519                                 }
 520                         } else {
 521                                 $this->mMarkPatrolledLink = '';
 522                         }
 523                 }
 524
 525                 return $this->mMarkPatrolledLink;
 526         }
 527
 528         /**
 529          * @param Revision $rev
 530          *
 531          * @return string
 532          */
 533         protected function revisionDeleteLink( $rev ) {
 534                 $link = Linker::getRevDeleteLink( $this->getUser(), $rev, $rev->getTitle() );
 535                 if ( $link !== '' ) {
 536                         $link = '&#160;&#160;&#160;' . $link . ' ';
 537                 }
 538
 539                 return $link;
 540         }
 541
 542         /**
 543          * Show the new revision of the page.
 544          */
 545         public function renderNewRevision() {
 546                 $out = $this->getOutput();
 547                 $revHeader = $this->getRevisionHeader( $this->mNewRev );
 548                 # Add "current version as of X" title
 549                 $out->addHTML( "<hr class='diff-hr' />
 550                 <h2 class='diff-currentversion-title'>{$revHeader}</h2>\n" );
 551                 # Page content may be handled by a hooked call instead...
 552                 # @codingStandardsIgnoreStart Ignoring long lines.
 553                 if ( Hooks::run( 'ArticleContentOnDiff', array( $this, $out ) ) ) {
 554                         $this->loadNewText();
 555                         $out->setRevisionId( $this->mNewid );
 556                         $out->setRevisionTimestamp( $this->mNewRev->getTimestamp() );
 557                         $out->setArticleFlag( true );
 558
 559                         // NOTE: only needed for B/C: custom rendering of JS/CSS via hook
 560                         if ( $this->mNewPage->isCssJsSubpage() || $this->mNewPage->isCssOrJsPage() ) {
 561                                 // This needs to be synchronised with Article::showCssOrJsPage(), which sucks
 562                                 // Give hooks a chance to customise the output
 563                                 // @todo standardize this crap into one function
 564                                 if ( ContentHandler::runLegacyHooks( 'ShowRawCssJs', array( $this->mNewContent, $this->mNewPage, $out ) ) ) {
 565                                         // NOTE: deprecated hook, B/C only
 566                                         // use the content object's own rendering
 567                                         $cnt = $this->mNewRev->getContent();
 568                                         $po = $cnt ? $cnt->getParserOutput( $this->mNewRev->getTitle(), $this->mNewRev->getId() ) : null;
 569                                         if ( $po ) {
 570                                                 $out->addParserOutputContent( $po );
 571                                         }
 572                                 }
 573                         } elseif ( !Hooks::run( 'ArticleContentViewCustom', array( $this->mNewContent, $this->mNewPage, $out ) ) ) {
 574                                 // Handled by extension
 575                         } elseif ( !ContentHandler::runLegacyHooks( 'ArticleViewCustom', array( $this->mNewContent, $this->mNewPage, $out ) ) ) {
 576                                 // NOTE: deprecated hook, B/C only
 577                                 // Handled by extension
 578                         } else {
 579                                 // Normal page
 580                                 if ( $this->getTitle()->equals( $this->mNewPage ) ) {
 581                                         // If the Title stored in the context is the same as the one
 582                                         // of the new revision, we can use its associated WikiPage
 583                                         // object.
 584                                         $wikiPage = $this->getWikiPage();
 585                                 } else {
 586                                         // Otherwise we need to create our own WikiPage object
 587                                         $wikiPage = WikiPage::factory( $this->mNewPage );
 588                                 }
 589
 590                                 $parserOutput = $this->getParserOutput( $wikiPage, $this->mNewRev );
 591
 592                                 # WikiPage::getParserOutput() should not return false, but just in case
 593                                 if ( $parserOutput ) {
 594                                         $out->addParserOutput( $parserOutput );
 595                                 }
 596                         }
 597                 }
 598                 # @codingStandardsIgnoreEnd
 599
 600                 # Add redundant patrol link on bottom...
 601                 $out->addHTML( $this->markPatrolledLink() );
 602
 603         }
 604
 605         protected function getParserOutput( WikiPage $page, Revision $rev ) {
 606                 $parserOptions = $page->makeParserOptions( $this->getContext() );
 607
 608                 if ( !$rev->isCurrent() || !$rev->getTitle()->quickUserCan( "edit" ) ) {
 609                         $parserOptions->setEditSection( false );
 610                 }
 611
 612                 $parserOutput = $page->getParserOutput( $parserOptions, $rev->getId() );
 613
 614                 return $parserOutput;
 615         }
 616
 617         /**
 618          * Get the diff text, send it to the OutputPage object
 619          * Returns false if the diff could not be generated, otherwise returns true
 620          *
 621          * @param string|bool $otitle Header for old text or false
 622          * @param string|bool $ntitle Header for new text or false
 623          * @param string $notice HTML between diff header and body
 624          *
 625          * @return bool
 626          */
 627         public function showDiff( $otitle, $ntitle, $notice = '' ) {
 628                 $diff = $this->getDiff( $otitle, $ntitle, $notice );
 629                 if ( $diff === false ) {
 630                         $this->showMissingRevision();
 631
 632                         return false;
 633                 } else {
 634                         $this->showDiffStyle();
 635                         $this->getOutput()->addHTML( $diff );
 636
 637                         return true;
 638                 }
 639         }
 640
 641         /**
 642          * Add style sheets and supporting JS for diff display.
 643          */
 644         public function showDiffStyle() {
 645                 $this->getOutput()->addModuleStyles( 'mediawiki.action.history.diff' );
 646         }
 647
 648         /**
 649          * Get complete diff table, including header
 650          *
 651          * @param string|bool $otitle Header for old text or false
 652          * @param string|bool $ntitle Header for new text or false
 653          * @param string $notice HTML between diff header and body
 654          *
 655          * @return mixed
 656          */
 657         public function getDiff( $otitle, $ntitle, $notice = '' ) {
 658                 $body = $this->getDiffBody();
 659                 if ( $body === false ) {
 660                         return false;
 661                 }
 662
 663                 $multi = $this->getMultiNotice();
 664                 // Display a message when the diff is empty
 665                 if ( $body === '' ) {
 666                         $notice .= '<div class="mw-diff-empty">' .
 667                                 $this->msg( 'diff-empty' )->parse() .
 668                                 "</div>\n";
 669                 }
 670
 671                 return $this->addHeader( $body, $otitle, $ntitle, $multi, $notice );
 672         }
 673
 674         /**
 675          * Get the diff table body, without header
 676          *
 677          * @return mixed (string/false)
 678          */
 679         public function getDiffBody() {
 680                 global $wgMemc;
 681                 $this->mCacheHit = true;
 682                 // Check if the diff should be hidden from this user
 683                 if ( !$this->loadRevisionData() ) {
 684
 685                         return false;
 686                 } elseif ( $this->mOldRev &&
 687                         !$this->mOldRev->userCan( Revision::DELETED_TEXT, $this->getUser() )
 688                 ) {
 689
 690                         return false;
 691                 } elseif ( $this->mNewRev &&
 692                         !$this->mNewRev->userCan( Revision::DELETED_TEXT, $this->getUser() )
 693                 ) {
 694
 695                         return false;
 696                 }
 697                 // Short-circuit
 698                 if ( $this->mOldRev === false || ( $this->mOldRev && $this->mNewRev
 699                         && $this->mOldRev->getID() == $this->mNewRev->getID() )
 700                 ) {
 701
 702                         return '';
 703                 }
 704                 // Cacheable?
 705                 $key = false;
 706                 if ( $this->mOldid && $this->mNewid ) {
 707                         $key = $this->getDiffBodyCacheKey();
 708
 709                         // Try cache
 710                         if ( !$this->mRefreshCache ) {
 711                                 $difftext = $wgMemc->get( $key );
 712                                 if ( $difftext ) {
 713                                         wfIncrStats( 'diff_cache_hit' );
 714                                         $difftext = $this->localiseLineNumbers( $difftext );
 715                                         $difftext .= "\n<!-- diff cache key $key -->\n";
 716
 717                                         return $difftext;
 718                                 }
 719                         } // don't try to load but save the result
 720                 }
 721                 $this->mCacheHit = false;
 722
 723                 // Loadtext is permission safe, this just clears out the diff
 724                 if ( !$this->loadText() ) {
 725
 726                         return false;
 727                 }
 728
 729                 $difftext = $this->generateContentDiffBody( $this->mOldContent, $this->mNewContent );
 730
 731                 // Save to cache for 7 days
 732                 if ( !Hooks::run( 'AbortDiffCache', array( &$this ) ) ) {
 733                         wfIncrStats( 'diff_uncacheable' );
 734                 } elseif ( $key !== false && $difftext !== false ) {
 735                         wfIncrStats( 'diff_cache_miss' );
 736                         $wgMemc->set( $key, $difftext, 7 * 86400 );
 737                 } else {
 738                         wfIncrStats( 'diff_uncacheable' );
 739                 }
 740                 // Replace line numbers with the text in the user's language
 741                 if ( $difftext !== false ) {
 742                         $difftext = $this->localiseLineNumbers( $difftext );
 743                 }
 744
 745                 return $difftext;
 746         }
 747
 748         /**
 749          * Returns the cache key for diff body text or content.
 750          *
 751          * @since 1.23
 752          *
 753          * @throws MWException
 754          * @return string
 755          */
 756         protected function getDiffBodyCacheKey() {
 757                 if ( !$this->mOldid || !$this->mNewid ) {
 758                         throw new MWException( 'mOldid and mNewid must be set to get diff cache key.' );
 759                 }
 760
 761                 return wfMemcKey( 'diff', 'version', MW_DIFF_VERSION,
 762                         'oldid', $this->mOldid, 'newid', $this->mNewid );
 763         }
 764
 765         /**
 766          * Generate a diff, no caching.
 767          *
 768          * This implementation uses generateTextDiffBody() to generate a diff based on the default
 769          * serialization of the given Content objects. This will fail if $old or $new are not
 770          * instances of TextContent.
 771          *
 772          * Subclasses may override this to provide a different rendering for the diff,
 773          * perhaps taking advantage of the content's native form. This is required for all content
 774          * models that are not text based.
 775          *
 776          * @since 1.21
 777          *
 778          * @param Content $old Old content
 779          * @param Content $new New content
 780          *
 781          * @throws MWException If old or new content is not an instance of TextContent.
 782          * @return bool|string
 783          */
 784         public function generateContentDiffBody( Content $old, Content $new ) {
 785                 if ( !( $old instanceof TextContent ) ) {
 786                         throw new MWException( "Diff not implemented for " . get_class( $old ) . "; " .
 787                                 "override generateContentDiffBody to fix this." );
 788                 }
 789
 790                 if ( !( $new instanceof TextContent ) ) {
 791                         throw new MWException( "Diff not implemented for " . get_class( $new ) . "; "
 792                                 . "override generateContentDiffBody to fix this." );
 793                 }
 794
 795                 $otext = $old->serialize();
 796                 $ntext = $new->serialize();
 797
 798                 return $this->generateTextDiffBody( $otext, $ntext );
 799         }
 800
 801         /**
 802          * Generate a diff, no caching
 803          *
 804          * @param string $otext Old text, must be already segmented
 805          * @param string $ntext New text, must be already segmented
 806          *
 807          * @return bool|string
 808          * @deprecated since 1.21, use generateContentDiffBody() instead!
 809          */
 810         public function generateDiffBody( $otext, $ntext ) {
 811                 ContentHandler::deprecated( __METHOD__, "1.21" );
 812
 813                 return $this->generateTextDiffBody( $otext, $ntext );
 814         }
 815
 816         /**
 817          * Generate a diff, no caching
 818          *
 819          * @todo move this to TextDifferenceEngine, make DifferenceEngine abstract. At some point.
 820          *
 821          * @param string $otext Old text, must be already segmented
 822          * @param string $ntext New text, must be already segmented
 823          *
 824          * @return bool|string
 825          */
 826         public function generateTextDiffBody( $otext, $ntext ) {
 827                 global $wgExternalDiffEngine, $wgContLang;
 828
 829                 $otext = str_replace( "\r\n", "\n", $otext );
 830                 $ntext = str_replace( "\r\n", "\n", $ntext );
 831
 832                 if ( $wgExternalDiffEngine == 'wikidiff' && function_exists( 'wikidiff_do_diff' ) ) {
 833                         # For historical reasons, external diff engine expects
 834                         # input text to be HTML-escaped already
 835                         $otext = htmlspecialchars( $wgContLang->segmentForDiff( $otext ) );
 836                         $ntext = htmlspecialchars( $wgContLang->segmentForDiff( $ntext ) );
 837
 838                         return $wgContLang->unsegmentForDiff( wikidiff_do_diff( $otext, $ntext, 2 ) ) .
 839                         $this->debug( 'wikidiff1' );
 840                 }
 841
 842                 if ( $wgExternalDiffEngine == 'wikidiff2' && function_exists( 'wikidiff2_do_diff' ) ) {
 843                         # Better external diff engine, the 2 may some day be dropped
 844                         # This one does the escaping and segmenting itself
 845                         wfProfileIn( 'wikidiff2_do_diff' );
 846                         $text = wikidiff2_do_diff( $otext, $ntext, 2 );
 847                         $text .= $this->debug( 'wikidiff2' );
 848                         wfProfileOut( 'wikidiff2_do_diff' );
 849
 850                         return $text;
 851                 }
 852                 if ( $wgExternalDiffEngine != 'wikidiff3' && $wgExternalDiffEngine !== false ) {
 853                         # Diff via the shell
 854                         $tmpDir = wfTempDir();
 855                         $tempName1 = tempnam( $tmpDir, 'diff_' );
 856                         $tempName2 = tempnam( $tmpDir, 'diff_' );
 857
 858                         $tempFile1 = fopen( $tempName1, "w" );
 859                         if ( !$tempFile1 ) {
 860
 861                                 return false;
 862                         }
 863                         $tempFile2 = fopen( $tempName2, "w" );
 864                         if ( !$tempFile2 ) {
 865
 866                                 return false;
 867                         }
 868                         fwrite( $tempFile1, $otext );
 869                         fwrite( $tempFile2, $ntext );
 870                         fclose( $tempFile1 );
 871                         fclose( $tempFile2 );
 872                         $cmd = wfEscapeShellArg( $wgExternalDiffEngine, $tempName1, $tempName2 );
 873                         wfProfileIn( __METHOD__ . "-shellexec" );
 874                         $difftext = wfShellExec( $cmd );
 875                         $difftext .= $this->debug( "external $wgExternalDiffEngine" );
 876                         wfProfileOut( __METHOD__ . "-shellexec" );
 877                         unlink( $tempName1 );
 878                         unlink( $tempName2 );
 879
 880                         return $difftext;
 881                 }
 882
 883                 # Native PHP diff
 884                 $ota = explode( "\n", $wgContLang->segmentForDiff( $otext ) );
 885                 $nta = explode( "\n", $wgContLang->segmentForDiff( $ntext ) );
 886                 $diffs = new Diff( $ota, $nta );
 887                 $formatter = new TableDiffFormatter();
 888                 $difftext = $wgContLang->unsegmentForDiff( $formatter->format( $diffs ) );
 889
 890                 return $difftext;
 891         }
 892
 893         /**
 894          * Generate a debug comment indicating diff generating time,
 895          * server node, and generator backend.
 896          *
 897          * @param string $generator : What diff engine was used
 898          *
 899          * @return string
 900          */
 901         protected function debug( $generator = "internal" ) {
 902                 global $wgShowHostnames;
 903                 if ( !$this->enableDebugComment ) {
 904                         return '';
 905                 }
 906                 $data = array( $generator );
 907                 if ( $wgShowHostnames ) {
 908                         $data[] = wfHostname();
 909                 }
 910                 $data[] = wfTimestamp( TS_DB );
 911
 912                 return "<!-- diff generator: " .
 913                         implode( " ", array_map( "htmlspecialchars", $data ) ) .
 914                         " -->\n";
 915         }
 916
 917         /**
 918          * Replace line numbers with the text in the user's language
 919          *
 920          * @param string $text
 921          *
 922          * @return mixed
 923          */
 924         public function localiseLineNumbers( $text ) {
 925                 return preg_replace_callback(
 926                         '/<!--LINE (\d+)-->/',
 927                         array( &$this, 'localiseLineNumbersCb' ),
 928                         $text
 929                 );
 930         }
 931
 932         public function localiseLineNumbersCb( $matches ) {
 933                 if ( $matches[1] === '1' && $this->mReducedLineNumbers ) {
 934                         return '';
 935                 }
 936
 937                 return $this->msg( 'lineno' )->numParams( $matches[1] )->escaped();
 938         }
 939
 940         /**
 941          * If there are revisions between the ones being compared, return a note saying so.
 942          *
 943          * @return string
 944          */
 945         public function getMultiNotice() {
 946                 if ( !is_object( $this->mOldRev ) || !is_object( $this->mNewRev ) ) {
 947                         return '';
 948                 } elseif ( !$this->mOldPage->equals( $this->mNewPage ) ) {
 949                         // Comparing two different pages? Count would be meaningless.
 950                         return '';
 951                 }
 952
 953                 if ( $this->mOldRev->getTimestamp() > $this->mNewRev->getTimestamp() ) {
 954                         $oldRev = $this->mNewRev; // flip
 955                         $newRev = $this->mOldRev; // flip
 956                 } else { // normal case
 957                         $oldRev = $this->mOldRev;
 958                         $newRev = $this->mNewRev;
 959                 }
 960
 961                 // Sanity: don't show the notice if too many rows must be scanned
 962                 // @todo show some special message for that case
 963                 $nEdits = $this->mNewPage->countRevisionsBetween( $oldRev, $newRev, 1000 );
 964                 if ( $nEdits > 0 && $nEdits <= 1000 ) {
 965                         $limit = 100; // use diff-multi-manyusers if too many users
 966                         $users = $this->mNewPage->getAuthorsBetween( $oldRev, $newRev, $limit );
 967                         $numUsers = count( $users );
 968
 969                         if ( $numUsers == 1 && $users[0] == $newRev->getRawUserText() ) {
 970                                 $numUsers = 0; // special case to say "by the same user" instead of "by one other user"
 971                         }
 972
 973                         return self::intermediateEditsMsg( $nEdits, $numUsers, $limit );
 974                 }
 975
 976                 return ''; // nothing
 977         }
 978
 979         /**
 980          * Get a notice about how many intermediate edits and users there are
 981          *
 982          * @param int $numEdits
 983          * @param int $numUsers
 984          * @param int $limit
 985          *
 986          * @return string
 987          */
 988         public static function intermediateEditsMsg( $numEdits, $numUsers, $limit ) {
 989                 if ( $numUsers === 0 ) {
 990                         $msg = 'diff-multi-sameuser';
 991                 } elseif ( $numUsers > $limit ) {
 992                         $msg = 'diff-multi-manyusers';
 993                         $numUsers = $limit;
 994                 } else {
 995                         $msg = 'diff-multi-otherusers';
 996                 }
 997
 998                 return wfMessage( $msg )->numParams( $numEdits, $numUsers )->parse();
 999         }
1000
1001         /**
1002          * Get a header for a specified revision.
1003          *
1004          * @param Revision $rev
1005          * @param string $complete 'complete' to get the header wrapped depending
1006          *        the visibility of the revision and a link to edit the page.
1007          *
1008          * @return string HTML fragment
1009          */
1010         protected function getRevisionHeader( Revision $rev, $complete = '' ) {
1011                 $lang = $this->getLanguage();
1012                 $user = $this->getUser();
1013                 $revtimestamp = $rev->getTimestamp();
1014                 $timestamp = $lang->userTimeAndDate( $revtimestamp, $user );
1015                 $dateofrev = $lang->userDate( $revtimestamp, $user );
1016                 $timeofrev = $lang->userTime( $revtimestamp, $user );
1017
1018                 $header = $this->msg(
1019                         $rev->isCurrent() ? 'currentrev-asof' : 'revisionasof',
1020                         $timestamp,
1021                         $dateofrev,
1022                         $timeofrev
1023                 )->escaped();
1024
1025                 if ( $complete !== 'complete' ) {
1026                         return $header;
1027                 }
1028
1029                 $title = $rev->getTitle();
1030
1031                 $header = Linker::linkKnown( $title, $header, array(),
1032                         array( 'oldid' => $rev->getID() ) );
1033
1034                 if ( $rev->userCan( Revision::DELETED_TEXT, $user ) ) {
1035                         $editQuery = array( 'action' => 'edit' );
1036                         if ( !$rev->isCurrent() ) {
1037                                 $editQuery['oldid'] = $rev->getID();
1038                         }
1039
1040                         $key = $title->quickUserCan( 'edit', $user ) ? 'editold' : 'viewsourceold';
1041                         $msg = $this->msg( $key )->escaped();
1042                         $editLink = $this->msg( 'parentheses' )->rawParams(
1043                                 Linker::linkKnown( $title, $msg, array( ), $editQuery ) )->escaped();
1044                         $header .= ' ' . Html::rawElement(
1045                                 'span',
1046                                 array( 'class' => 'mw-diff-edit' ),
1047                                 $editLink
1048                         );
1049                         if ( $rev->isDeleted( Revision::DELETED_TEXT ) ) {
1050                                 $header = Html::rawElement(
1051                                         'span',
1052                                         array( 'class' => 'history-deleted' ),
1053                                         $header
1054                                 );
1055                         }
1056                 } else {
1057                         $header = Html::rawElement( 'span', array( 'class' => 'history-deleted' ), $header );
1058                 }
1059
1060                 return $header;
1061         }
1062
1063         /**
1064          * Add the header to a diff body
1065          *
1066          * @param string $diff Diff body
1067          * @param string $otitle Old revision header
1068          * @param string $ntitle New revision header
1069          * @param string $multi Notice telling user that there are intermediate
1070          *   revisions between the ones being compared
1071          * @param string $notice Other notices, e.g. that user is viewing deleted content
1072          *
1073          * @return string
1074          */
1075         public function addHeader( $diff, $otitle, $ntitle, $multi = '', $notice = '' ) {
1076                 // shared.css sets diff in interface language/dir, but the actual content
1077                 // is often in a different language, mostly the page content language/dir
1078                 $tableClass = 'diff diff-contentalign-' . htmlspecialchars( $this->getDiffLang()->alignStart() );
1079                 $header = "<table class='$tableClass'>";
1080
1081                 if ( !$diff && !$otitle ) {
1082                         $header .= "
1083                         <tr style='vertical-align: top;'>
1084                         <td class='diff-ntitle'>{$ntitle}</td>
1085                         </tr>";
1086                         $multiColspan = 1;
1087                 } else {
1088                         if ( $diff ) { // Safari/Chrome show broken output if cols not used
1089                                 $header .= "
1090                                 <col class='diff-marker' />
1091                                 <col class='diff-content' />
1092                                 <col class='diff-marker' />
1093                                 <col class='diff-content' />";
1094                                 $colspan = 2;
1095                                 $multiColspan = 4;
1096                         } else {
1097                                 $colspan = 1;
1098                                 $multiColspan = 2;
1099                         }
1100                         if ( $otitle || $ntitle ) {
1101                                 $header .= "
1102                                 <tr style='vertical-align: top;'>
1103                                 <td colspan='$colspan' class='diff-otitle'>{$otitle}</td>
1104                                 <td colspan='$colspan' class='diff-ntitle'>{$ntitle}</td>
1105                                 </tr>";
1106                         }
1107                 }
1108
1109                 if ( $multi != '' ) {
1110                         $header .= "<tr><td colspan='{$multiColspan}' style='text-align: center;' " .
1111                                 "class='diff-multi'>{$multi}</td></tr>";
1112                 }
1113                 if ( $notice != '' ) {
1114                         $header .= "<tr><td colspan='{$multiColspan}' style='text-align: center;'>{$notice}</td></tr>";
1115                 }
1116
1117                 return $header . $diff . "</table>";
1118         }
1119
1120         /**
1121          * Use specified text instead of loading from the database
1122          * @deprecated since 1.21, use setContent() instead.
1123          */
1124         public function setText( $oldText, $newText ) {
1125                 ContentHandler::deprecated( __METHOD__, "1.21" );
1126
1127                 $oldContent = ContentHandler::makeContent( $oldText, $this->getTitle() );
1128                 $newContent = ContentHandler::makeContent( $newText, $this->getTitle() );
1129
1130                 $this->setContent( $oldContent, $newContent );
1131         }
1132
1133         /**
1134          * Use specified text instead of loading from the database
1135          * @param Content $oldContent
1136          * @param Content $newContent
1137          * @since 1.21
1138          */
1139         public function setContent( Content $oldContent, Content $newContent ) {
1140                 $this->mOldContent = $oldContent;
1141                 $this->mNewContent = $newContent;
1142
1143                 $this->mTextLoaded = 2;
1144                 $this->mRevisionsLoaded = true;
1145         }
1146
1147         /**
1148          * Set the language in which the diff text is written
1149          * (Defaults to page content language).
1150          * @param Language|string $lang
1151          * @since 1.19
1152          */
1153         public function setTextLanguage( $lang ) {
1154                 $this->mDiffLang = wfGetLangObj( $lang );
1155         }
1156
1157         /**
1158          * Maps a revision pair definition as accepted by DifferenceEngine constructor
1159          * to a pair of actual integers representing revision ids.
1160          *
1161          * @param int $old Revision id, e.g. from URL parameter 'oldid'
1162          * @param int|string $new Revision id or strings 'next' or 'prev', e.g. from URL parameter 'diff'
1163          *
1164          * @return int[] List of two revision ids, older first, later second.
1165          *     Zero signifies invalid argument passed.
1166          *     false signifies that there is no previous/next revision ($old is the oldest/newest one).
1167          */
1168         public function mapDiffPrevNext( $old, $new ) {
1169                 if ( $new === 'prev' ) {
1170                         // Show diff between revision $old and the previous one. Get previous one from DB.
1171                         $newid = intval( $old );
1172                         $oldid = $this->getTitle()->getPreviousRevisionID( $newid );
1173                 } elseif ( $new === 'next' ) {
1174                         // Show diff between revision $old and the next one. Get next one from DB.
1175                         $oldid = intval( $old );
1176                         $newid = $this->getTitle()->getNextRevisionID( $oldid );
1177                 } else {
1178                         $oldid = intval( $old );
1179                         $newid = intval( $new );
1180                 }
1181
1182                 return array( $oldid, $newid );
1183         }
1184
1185         /**
1186          * Load revision IDs
1187          */
1188         private function loadRevisionIds() {
1189                 if ( $this->mRevisionsIdsLoaded ) {
1190                         return;
1191                 }
1192
1193                 $this->mRevisionsIdsLoaded = true;
1194
1195                 $old = $this->mOldid;
1196                 $new = $this->mNewid;
1197
1198                 list( $this->mOldid, $this->mNewid ) = self::mapDiffPrevNext( $old, $new );
1199                 if ( $new === 'next' && $this->mNewid === false ) {
1200                         # if no result, NewId points to the newest old revision. The only newer
1201                         # revision is cur, which is "0".
1202                         $this->mNewid = 0;
1203                 }
1204
1205                 Hooks::run(
1206                         'NewDifferenceEngine',
1207                         array( $this->getTitle(), &$this->mOldid, &$this->mNewid, $old, $new )
1208                 );
1209         }
1210
1211         /**
1212          * Load revision metadata for the specified articles. If newid is 0, then compare
1213          * the old article in oldid to the current article; if oldid is 0, then
1214          * compare the current article to the immediately previous one (ignoring the
1215          * value of newid).
1216          *
1217          * If oldid is false, leave the corresponding revision object set
1218          * to false. This is impossible via ordinary user input, and is provided for
1219          * API convenience.
1220          *
1221          * @return bool
1222          */
1223         public function loadRevisionData() {
1224                 if ( $this->mRevisionsLoaded ) {
1225                         return true;
1226                 }
1227
1228                 // Whether it succeeds or fails, we don't want to try again
1229                 $this->mRevisionsLoaded = true;
1230
1231                 $this->loadRevisionIds();
1232
1233                 // Load the new revision object
1234                 if ( $this->mNewid ) {
1235                         $this->mNewRev = Revision::newFromId( $this->mNewid );
1236                 } else {
1237                         $this->mNewRev = Revision::newFromTitle(
1238                                 $this->getTitle(),
1239                                 false,
1240                                 Revision::READ_NORMAL
1241                         );
1242                 }
1243
1244                 if ( !$this->mNewRev instanceof Revision ) {
1245                         return false;
1246                 }
1247
1248                 // Update the new revision ID in case it was 0 (makes life easier doing UI stuff)
1249                 $this->mNewid = $this->mNewRev->getId();
1250                 $this->mNewPage = $this->mNewRev->getTitle();
1251
1252                 // Load the old revision object
1253                 $this->mOldRev = false;
1254                 if ( $this->mOldid ) {
1255                         $this->mOldRev = Revision::newFromId( $this->mOldid );
1256                 } elseif ( $this->mOldid === 0 ) {
1257                         $rev = $this->mNewRev->getPrevious();
1258                         if ( $rev ) {
1259                                 $this->mOldid = $rev->getId();
1260                                 $this->mOldRev = $rev;
1261                         } else {
1262                                 // No previous revision; mark to show as first-version only.
1263                                 $this->mOldid = false;
1264                                 $this->mOldRev = false;
1265                         }
1266                 } /* elseif ( $this->mOldid === false ) leave mOldRev false; */
1267
1268                 if ( is_null( $this->mOldRev ) ) {
1269                         return false;
1270                 }
1271
1272                 if ( $this->mOldRev ) {
1273                         $this->mOldPage = $this->mOldRev->getTitle();
1274                 }
1275
1276                 // Load tags information for both revisions
1277                 $dbr = wfGetDB( DB_SLAVE );
1278                 if ( $this->mOldid !== false ) {
1279                         $this->mOldTags = $dbr->selectField(
1280                                 'tag_summary',
1281                                 'ts_tags',
1282                                 array( 'ts_rev_id' => $this->mOldid ),
1283                                 __METHOD__
1284                         );
1285                 } else {
1286                         $this->mOldTags = false;
1287                 }
1288                 $this->mNewTags = $dbr->selectField(
1289                         'tag_summary',
1290                         'ts_tags',
1291                         array( 'ts_rev_id' => $this->mNewid ),
1292                         __METHOD__
1293                 );
1294
1295                 return true;
1296         }
1297
1298         /**
1299          * Load the text of the revisions, as well as revision data.
1300          *
1301          * @return bool
1302          */
1303         public function loadText() {
1304                 if ( $this->mTextLoaded == 2 ) {
1305                         return true;
1306                 }
1307
1308                 // Whether it succeeds or fails, we don't want to try again
1309                 $this->mTextLoaded = 2;
1310
1311                 if ( !$this->loadRevisionData() ) {
1312                         return false;
1313                 }
1314
1315                 if ( $this->mOldRev ) {
1316                         $this->mOldContent = $this->mOldRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1317                         if ( $this->mOldContent === null ) {
1318                                 return false;
1319                         }
1320                 }
1321
1322                 if ( $this->mNewRev ) {
1323                         $this->mNewContent = $this->mNewRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1324                         if ( $this->mNewContent === null ) {
1325                                 return false;
1326                         }
1327                 }
1328
1329                 return true;
1330         }
1331
1332         /**
1333          * Load the text of the new revision, not the old one
1334          *
1335          * @return bool
1336          */
1337         public function loadNewText() {
1338                 if ( $this->mTextLoaded >= 1 ) {
1339                         return true;
1340                 }
1341
1342                 $this->mTextLoaded = 1;
1343
1344                 if ( !$this->loadRevisionData() ) {
1345                         return false;
1346                 }
1347
1348                 $this->mNewContent = $this->mNewRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1349
1350                 return true;
1351         }
1352
1353 }