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         /** @var bool Refresh the diff cache */
  99         protected $mRefreshCache = false;
 100
 101         /**#@-*/
 102
 103         /**
 104          * Constructor
 105          * @param IContextSource $context Context to use, anything else will be ignored
 106          * @param int $old Old ID we want to show and diff with.
 107          * @param string|int $new Either revision ID or 'prev' or 'next'. Default: 0.
 108          * @param int $rcid Deprecated, no longer used!
 109          * @param bool $refreshCache If set, refreshes the diff cache
 110          * @param bool $unhide If set, allow viewing deleted revs
 111          */
 112         public function __construct( $context = null, $old = 0, $new = 0, $rcid = 0,
 113                 $refreshCache = false, $unhide = false
 114         ) {
 115                 if ( $context instanceof IContextSource ) {
 116                         $this->setContext( $context );
 117                 }
 118
 119                 wfDebug( "DifferenceEngine old '$old' new '$new' rcid '$rcid'\n" );
 120
 121                 $this->mOldid = $old;
 122                 $this->mNewid = $new;
 123                 $this->mRefreshCache = $refreshCache;
 124                 $this->unhide = $unhide;
 125         }
 126
 127         /**
 128          * @param bool $value
 129          */
 130         public function setReducedLineNumbers( $value = true ) {
 131                 $this->mReducedLineNumbers = $value;
 132         }
 133
 134         /**
 135          * @return Language
 136          */
 137         public function getDiffLang() {
 138                 if ( $this->mDiffLang === null ) {
 139                         # Default language in which the diff text is written.
 140                         $this->mDiffLang = $this->getTitle()->getPageLanguage();
 141                 }
 142
 143                 return $this->mDiffLang;
 144         }
 145
 146         /**
 147          * @return bool
 148          */
 149         public function wasCacheHit() {
 150                 return $this->mCacheHit;
 151         }
 152
 153         /**
 154          * @return int
 155          */
 156         public function getOldid() {
 157                 $this->loadRevisionIds();
 158
 159                 return $this->mOldid;
 160         }
 161
 162         /**
 163          * @return bool|int
 164          */
 165         public function getNewid() {
 166                 $this->loadRevisionIds();
 167
 168                 return $this->mNewid;
 169         }
 170
 171         /**
 172          * Look up a special:Undelete link to the given deleted revision id,
 173          * as a workaround for being unable to load deleted diffs in currently.
 174          *
 175          * @param int $id Revision ID
 176          *
 177          * @return mixed URL or false
 178          */
 179         public function deletedLink( $id ) {
 180                 if ( $this->getUser()->isAllowed( 'deletedhistory' ) ) {
 181                         $dbr = wfGetDB( DB_SLAVE );
 182                         $row = $dbr->selectRow( 'archive', '*',
 183                                 array( 'ar_rev_id' => $id ),
 184                                 __METHOD__ );
 185                         if ( $row ) {
 186                                 $rev = Revision::newFromArchiveRow( $row );
 187                                 $title = Title::makeTitleSafe( $row->ar_namespace, $row->ar_title );
 188
 189                                 return SpecialPage::getTitleFor( 'Undelete' )->getFullURL( array(
 190                                         'target' => $title->getPrefixedText(),
 191                                         'timestamp' => $rev->getTimestamp()
 192                                 ) );
 193                         }
 194                 }
 195
 196                 return false;
 197         }
 198
 199         /**
 200          * Build a wikitext link toward a deleted revision, if viewable.
 201          *
 202          * @param int $id Revision ID
 203          *
 204          * @return string Wikitext fragment
 205          */
 206         public function deletedIdMarker( $id ) {
 207                 $link = $this->deletedLink( $id );
 208                 if ( $link ) {
 209                         return "[$link $id]";
 210                 } else {
 211                         return $id;
 212                 }
 213         }
 214
 215         private function showMissingRevision() {
 216                 $out = $this->getOutput();
 217
 218                 $missing = array();
 219                 if ( $this->mOldRev === null ||
 220                         ( $this->mOldRev && $this->mOldContent === null )
 221                 ) {
 222                         $missing[] = $this->deletedIdMarker( $this->mOldid );
 223                 }
 224                 if ( $this->mNewRev === null ||
 225                         ( $this->mNewRev && $this->mNewContent === null )
 226                 ) {
 227                         $missing[] = $this->deletedIdMarker( $this->mNewid );
 228                 }
 229
 230                 $out->setPageTitle( $this->msg( 'errorpagetitle' ) );
 231                 $msg = $this->msg( 'difference-missing-revision' )
 232                         ->params( $this->getLanguage()->listToText( $missing ) )
 233                         ->numParams( count( $missing ) )
 234                         ->parseAsBlock();
 235                 $out->addHtml( $msg );
 236         }
 237
 238         public function showDiffPage( $diffOnly = false ) {
 239
 240                 # Allow frames except in certain special cases
 241                 $out = $this->getOutput();
 242                 $out->allowClickjacking();
 243                 $out->setRobotPolicy( 'noindex,nofollow' );
 244
 245                 if ( !$this->loadRevisionData() ) {
 246                         $this->showMissingRevision();
 247
 248                         return;
 249                 }
 250
 251                 $user = $this->getUser();
 252                 $permErrors = $this->mNewPage->getUserPermissionsErrors( 'read', $user );
 253                 if ( $this->mOldPage ) { # mOldPage might not be set, see below.
 254                         $permErrors = wfMergeErrorArrays( $permErrors,
 255                                 $this->mOldPage->getUserPermissionsErrors( 'read', $user ) );
 256                 }
 257                 if ( count( $permErrors ) ) {
 258                         throw new PermissionsError( 'read', $permErrors );
 259                 }
 260
 261                 $rollback = '';
 262
 263                 $query = array();
 264                 # Carry over 'diffonly' param via navigation links
 265                 if ( $diffOnly != $user->getBoolOption( 'diffonly' ) ) {
 266                         $query['diffonly'] = $diffOnly;
 267                 }
 268                 # Cascade unhide param in links for easy deletion browsing
 269                 if ( $this->unhide ) {
 270                         $query['unhide'] = 1;
 271                 }
 272
 273                 # Check if one of the revisions is deleted/suppressed
 274                 $deleted = $suppressed = false;
 275                 $allowed = $this->mNewRev->userCan( Revision::DELETED_TEXT, $user );
 276
 277                 $revisionTools = array();
 278
 279                 # mOldRev is false if the difference engine is called with a "vague" query for
 280                 # a diff between a version V and its previous version V' AND the version V
 281                 # is the first version of that article. In that case, V' does not exist.
 282                 if ( $this->mOldRev === false ) {
 283                         $out->setPageTitle( $this->msg( 'difference-title', $this->mNewPage->getPrefixedText() ) );
 284                         $samePage = true;
 285                         $oldHeader = '';
 286                 } else {
 287                         Hooks::run( 'DiffViewHeader', array( $this, $this->mOldRev, $this->mNewRev ) );
 288
 289                         if ( $this->mNewPage->equals( $this->mOldPage ) ) {
 290                                 $out->setPageTitle( $this->msg( 'difference-title', $this->mNewPage->getPrefixedText() ) );
 291                                 $samePage = true;
 292                         } else {
 293                                 $out->setPageTitle( $this->msg( 'difference-title-multipage',
 294                                         $this->mOldPage->getPrefixedText(), $this->mNewPage->getPrefixedText() ) );
 295                                 $out->addSubtitle( $this->msg( 'difference-multipage' ) );
 296                                 $samePage = false;
 297                         }
 298
 299                         if ( $samePage && $this->mNewPage->quickUserCan( 'edit', $user ) ) {
 300                                 if ( $this->mNewRev->isCurrent() && $this->mNewPage->userCan( 'rollback', $user ) ) {
 301                                         $rollbackLink = Linker::generateRollback( $this->mNewRev, $this->getContext() );
 302                                         if ( $rollbackLink ) {
 303                                                 $out->preventClickjacking();
 304                                                 $rollback = '&#160;&#160;&#160;' . $rollbackLink;
 305                                         }
 306                                 }
 307
 308                                 if ( !$this->mOldRev->isDeleted( Revision::DELETED_TEXT ) &&
 309                                         !$this->mNewRev->isDeleted( Revision::DELETED_TEXT )
 310                                 ) {
 311                                         $undoLink = Html::element( 'a', array(
 312                                                         'href' => $this->mNewPage->getLocalURL( array(
 313                                                                 'action' => 'edit',
 314                                                                 'undoafter' => $this->mOldid,
 315                                                                 'undo' => $this->mNewid
 316                                                         ) ),
 317                                                         'title' => Linker::titleAttrib( 'undo' ),
 318                                                 ),
 319                                                 $this->msg( 'editundo' )->text()
 320                                         );
 321                                         $revisionTools['mw-diff-undo'] = $undoLink;
 322                                 }
 323                         }
 324
 325                         # Make "previous revision link"
 326                         if ( $samePage && $this->mOldRev->getPrevious() ) {
 327                                 $prevlink = Linker::linkKnown(
 328                                         $this->mOldPage,
 329                                         $this->msg( 'previousdiff' )->escaped(),
 330                                         array( 'id' => 'differences-prevlink' ),
 331                                         array( 'diff' => 'prev', 'oldid' => $this->mOldid ) + $query
 332                                 );
 333                         } else {
 334                                 $prevlink = '&#160;';
 335                         }
 336
 337                         if ( $this->mOldRev->isMinor() ) {
 338                                 $oldminor = ChangesList::flag( 'minor' );
 339                         } else {
 340                                 $oldminor = '';
 341                         }
 342
 343                         $ldel = $this->revisionDeleteLink( $this->mOldRev );
 344                         $oldRevisionHeader = $this->getRevisionHeader( $this->mOldRev, 'complete' );
 345                         $oldChangeTags = ChangeTags::formatSummaryRow( $this->mOldTags, 'diff' );
 346
 347                         $oldHeader = '<div id="mw-diff-otitle1"><strong>' . $oldRevisionHeader . '</strong></div>' .
 348                                 '<div id="mw-diff-otitle2">' .
 349                                 Linker::revUserTools( $this->mOldRev, !$this->unhide ) . '</div>' .
 350                                 '<div id="mw-diff-otitle3">' . $oldminor .
 351                                 Linker::revComment( $this->mOldRev, !$diffOnly, !$this->unhide ) . $ldel . '</div>' .
 352                                 '<div id="mw-diff-otitle5">' . $oldChangeTags[0] . '</div>' .
 353                                 '<div id="mw-diff-otitle4">' . $prevlink . '</div>';
 354
 355                         if ( $this->mOldRev->isDeleted( Revision::DELETED_TEXT ) ) {
 356                                 $deleted = true; // old revisions text is hidden
 357                                 if ( $this->mOldRev->isDeleted( Revision::DELETED_RESTRICTED ) ) {
 358                                         $suppressed = true; // also suppressed
 359                                 }
 360                         }
 361
 362                         # Check if this user can see the revisions
 363                         if ( !$this->mOldRev->userCan( Revision::DELETED_TEXT, $user ) ) {
 364                                 $allowed = false;
 365                         }
 366                 }
 367
 368                 # Make "next revision link"
 369                 # Skip next link on the top revision
 370                 if ( $samePage && !$this->mNewRev->isCurrent() ) {
 371                         $nextlink = Linker::linkKnown(
 372                                 $this->mNewPage,
 373                                 $this->msg( 'nextdiff' )->escaped(),
 374                                 array( 'id' => 'differences-nextlink' ),
 375                                 array( 'diff' => 'next', 'oldid' => $this->mNewid ) + $query
 376                         );
 377                 } else {
 378                         $nextlink = '&#160;';
 379                 }
 380
 381                 if ( $this->mNewRev->isMinor() ) {
 382                         $newminor = ChangesList::flag( 'minor' );
 383                 } else {
 384                         $newminor = '';
 385                 }
 386
 387                 # Handle RevisionDelete links...
 388                 $rdel = $this->revisionDeleteLink( $this->mNewRev );
 389
 390                 # Allow extensions to define their own revision tools
 391                 Hooks::run( 'DiffRevisionTools',
 392                         array( $this->mNewRev, &$revisionTools, $this->mOldRev, $user ) );
 393                 $formattedRevisionTools = array();
 394                 // Put each one in parentheses (poor man's button)
 395                 foreach ( $revisionTools as $key => $tool ) {
 396                         $toolClass = is_string( $key ) ? $key : 'mw-diff-tool';
 397                         $element = Html::rawElement(
 398                                 'span',
 399                                 array( 'class' => $toolClass ),
 400                                 $this->msg( 'parentheses' )->rawParams( $tool )->escaped()
 401                         );
 402                         $formattedRevisionTools[] = $element;
 403                 }
 404                 $newRevisionHeader = $this->getRevisionHeader( $this->mNewRev, 'complete' ) .
 405                         ' ' . implode( ' ', $formattedRevisionTools );
 406                 $newChangeTags = ChangeTags::formatSummaryRow( $this->mNewTags, 'diff' );
 407
 408                 $newHeader = '<div id="mw-diff-ntitle1"><strong>' . $newRevisionHeader . '</strong></div>' .
 409                         '<div id="mw-diff-ntitle2">' . Linker::revUserTools( $this->mNewRev, !$this->unhide ) .
 410                         " $rollback</div>" .
 411                         '<div id="mw-diff-ntitle3">' . $newminor .
 412                         Linker::revComment( $this->mNewRev, !$diffOnly, !$this->unhide ) . $rdel . '</div>' .
 413                         '<div id="mw-diff-ntitle5">' . $newChangeTags[0] . '</div>' .
 414                         '<div id="mw-diff-ntitle4">' . $nextlink . $this->markPatrolledLink() . '</div>';
 415
 416                 if ( $this->mNewRev->isDeleted( Revision::DELETED_TEXT ) ) {
 417                         $deleted = true; // new revisions text is hidden
 418                         if ( $this->mNewRev->isDeleted( Revision::DELETED_RESTRICTED ) ) {
 419                                 $suppressed = true; // also suppressed
 420                         }
 421                 }
 422
 423                 # If the diff cannot be shown due to a deleted revision, then output
 424                 # the diff header and links to unhide (if available)...
 425                 if ( $deleted && ( !$this->unhide || !$allowed ) ) {
 426                         $this->showDiffStyle();
 427                         $multi = $this->getMultiNotice();
 428                         $out->addHTML( $this->addHeader( '', $oldHeader, $newHeader, $multi ) );
 429                         if ( !$allowed ) {
 430                                 $msg = $suppressed ? 'rev-suppressed-no-diff' : 'rev-deleted-no-diff';
 431                                 # Give explanation for why revision is not visible
 432                                 $out->wrapWikiMsg( "<div id='mw-$msg' class='mw-warning plainlinks'>\n$1\n</div>\n",
 433                                         array( $msg ) );
 434                         } else {
 435                                 # Give explanation and add a link to view the diff...
 436                                 $query = $this->getRequest()->appendQueryValue( 'unhide', '1', true );
 437                                 $link = $this->getTitle()->getFullURL( $query );
 438                                 $msg = $suppressed ? 'rev-suppressed-unhide-diff' : 'rev-deleted-unhide-diff';
 439                                 $out->wrapWikiMsg(
 440                                         "<div id='mw-$msg' class='mw-warning plainlinks'>\n$1\n</div>\n",
 441                                         array( $msg, $link )
 442                                 );
 443                         }
 444                 # Otherwise, output a regular diff...
 445                 } else {
 446                         # Add deletion notice if the user is viewing deleted content
 447                         $notice = '';
 448                         if ( $deleted ) {
 449                                 $msg = $suppressed ? 'rev-suppressed-diff-view' : 'rev-deleted-diff-view';
 450                                 $notice = "<div id='mw-$msg' class='mw-warning plainlinks'>\n" .
 451                                         $this->msg( $msg )->parse() .
 452                                         "</div>\n";
 453                         }
 454                         $this->showDiff( $oldHeader, $newHeader, $notice );
 455                         if ( !$diffOnly ) {
 456                                 $this->renderNewRevision();
 457                         }
 458                 }
 459         }
 460
 461         /**
 462          * Get a link to mark the change as patrolled, or '' if there's either no
 463          * revision to patrol or the user is not allowed to to it.
 464          * Side effect: When the patrol link is build, this method will call
 465          * OutputPage::preventClickjacking() and load mediawiki.page.patrol.ajax.
 466          *
 467          * @return string
 468          */
 469         protected function markPatrolledLink() {
 470                 global $wgUseRCPatrol, $wgEnableAPI, $wgEnableWriteAPI;
 471                 $user = $this->getUser();
 472
 473                 if ( $this->mMarkPatrolledLink === null ) {
 474                         // Prepare a change patrol link, if applicable
 475                         if (
 476                                 // Is patrolling enabled and the user allowed to?
 477                                 $wgUseRCPatrol && $this->mNewPage->quickUserCan( 'patrol', $user ) &&
 478                                 // Only do this if the revision isn't more than 6 hours older
 479                                 // than the Max RC age (6h because the RC might not be cleaned out regularly)
 480                                 RecentChange::isInRCLifespan( $this->mNewRev->getTimestamp(), 21600 )
 481                         ) {
 482                                 // Look for an unpatrolled change corresponding to this diff
 483
 484                                 $db = wfGetDB( DB_SLAVE );
 485                                 $change = RecentChange::newFromConds(
 486                                         array(
 487                                                 'rc_timestamp' => $db->timestamp( $this->mNewRev->getTimestamp() ),
 488                                                 'rc_this_oldid' => $this->mNewid,
 489                                                 'rc_patrolled' => 0
 490                                         ),
 491                                         __METHOD__
 492                                 );
 493
 494                                 if ( $change && !$change->getPerformer()->equals( $user ) ) {
 495                                         $rcid = $change->getAttribute( 'rc_id' );
 496                                 } else {
 497                                         // None found or the page has been created by the current user.
 498                                         // If the user could patrol this it already would be patrolled
 499                                         $rcid = 0;
 500                                 }
 501                                 // Build the link
 502                                 if ( $rcid ) {
 503                                         $this->getOutput()->preventClickjacking();
 504                                         if ( $wgEnableAPI && $wgEnableWriteAPI
 505                                                 && $user->isAllowed( 'writeapi' )
 506                                         ) {
 507                                                 $this->getOutput()->addModules( 'mediawiki.page.patrol.ajax' );
 508                                         }
 509
 510                                         $token = $user->getEditToken( $rcid );
 511                                         $this->mMarkPatrolledLink = ' <span class="patrollink">[' . Linker::linkKnown(
 512                                                 $this->mNewPage,
 513                                                 $this->msg( 'markaspatrolleddiff' )->escaped(),
 514                                                 array(),
 515                                                 array(
 516                                                         'action' => 'markpatrolled',
 517                                                         'rcid' => $rcid,
 518                                                         'token' => $token,
 519                                                 )
 520                                         ) . ']</span>';
 521                                 } else {
 522                                         $this->mMarkPatrolledLink = '';
 523                                 }
 524                         } else {
 525                                 $this->mMarkPatrolledLink = '';
 526                         }
 527                 }
 528
 529                 return $this->mMarkPatrolledLink;
 530         }
 531
 532         /**
 533          * @param Revision $rev
 534          *
 535          * @return string
 536          */
 537         protected function revisionDeleteLink( $rev ) {
 538                 $link = Linker::getRevDeleteLink( $this->getUser(), $rev, $rev->getTitle() );
 539                 if ( $link !== '' ) {
 540                         $link = '&#160;&#160;&#160;' . $link . ' ';
 541                 }
 542
 543                 return $link;
 544         }
 545
 546         /**
 547          * Show the new revision of the page.
 548          */
 549         public function renderNewRevision() {
 550                 $out = $this->getOutput();
 551                 $revHeader = $this->getRevisionHeader( $this->mNewRev );
 552                 # Add "current version as of X" title
 553                 $out->addHTML( "<hr class='diff-hr' id='mw-oldid' />
 554                 <h2 class='diff-currentversion-title'>{$revHeader}</h2>\n" );
 555                 # Page content may be handled by a hooked call instead...
 556                 # @codingStandardsIgnoreStart Ignoring long lines.
 557                 if ( Hooks::run( 'ArticleContentOnDiff', array( $this, $out ) ) ) {
 558                         $this->loadNewText();
 559                         $out->setRevisionId( $this->mNewid );
 560                         $out->setRevisionTimestamp( $this->mNewRev->getTimestamp() );
 561                         $out->setArticleFlag( true );
 562
 563                         // NOTE: only needed for B/C: custom rendering of JS/CSS via hook
 564                         if ( $this->mNewPage->isCssJsSubpage() || $this->mNewPage->isCssOrJsPage() ) {
 565                                 // This needs to be synchronised with Article::showCssOrJsPage(), which sucks
 566                                 // Give hooks a chance to customise the output
 567                                 // @todo standardize this crap into one function
 568                                 if ( ContentHandler::runLegacyHooks( 'ShowRawCssJs', array( $this->mNewContent, $this->mNewPage, $out ) ) ) {
 569                                         // NOTE: deprecated hook, B/C only
 570                                         // use the content object's own rendering
 571                                         $cnt = $this->mNewRev->getContent();
 572                                         $po = $cnt ? $cnt->getParserOutput( $this->mNewRev->getTitle(), $this->mNewRev->getId() ) : null;
 573                                         if ( $po ) {
 574                                                 $out->addParserOutputContent( $po );
 575                                         }
 576                                 }
 577                         } elseif ( !Hooks::run( 'ArticleContentViewCustom', array( $this->mNewContent, $this->mNewPage, $out ) ) ) {
 578                                 // Handled by extension
 579                         } elseif ( !ContentHandler::runLegacyHooks( 'ArticleViewCustom', array( $this->mNewContent, $this->mNewPage, $out ) ) ) {
 580                                 // NOTE: deprecated hook, B/C only
 581                                 // Handled by extension
 582                         } else {
 583                                 // Normal page
 584                                 if ( $this->getTitle()->equals( $this->mNewPage ) ) {
 585                                         // If the Title stored in the context is the same as the one
 586                                         // of the new revision, we can use its associated WikiPage
 587                                         // object.
 588                                         $wikiPage = $this->getWikiPage();
 589                                 } else {
 590                                         // Otherwise we need to create our own WikiPage object
 591                                         $wikiPage = WikiPage::factory( $this->mNewPage );
 592                                 }
 593
 594                                 $parserOutput = $this->getParserOutput( $wikiPage, $this->mNewRev );
 595
 596                                 # WikiPage::getParserOutput() should not return false, but just in case
 597                                 if ( $parserOutput ) {
 598                                         $out->addParserOutput( $parserOutput );
 599                                 }
 600                         }
 601                 }
 602                 # @codingStandardsIgnoreEnd
 603
 604                 # Add redundant patrol link on bottom...
 605                 $out->addHTML( $this->markPatrolledLink() );
 606
 607         }
 608
 609         protected function getParserOutput( WikiPage $page, Revision $rev ) {
 610                 $parserOptions = $page->makeParserOptions( $this->getContext() );
 611
 612                 if ( !$rev->isCurrent() || !$rev->getTitle()->quickUserCan( 'edit', $this->getUser() ) ) {
 613                         $parserOptions->setEditSection( false );
 614                 }
 615
 616                 $parserOutput = $page->getParserOutput( $parserOptions, $rev->getId() );
 617
 618                 return $parserOutput;
 619         }
 620
 621         /**
 622          * Get the diff text, send it to the OutputPage object
 623          * Returns false if the diff could not be generated, otherwise returns true
 624          *
 625          * @param string|bool $otitle Header for old text or false
 626          * @param string|bool $ntitle Header for new text or false
 627          * @param string $notice HTML between diff header and body
 628          *
 629          * @return bool
 630          */
 631         public function showDiff( $otitle, $ntitle, $notice = '' ) {
 632                 $diff = $this->getDiff( $otitle, $ntitle, $notice );
 633                 if ( $diff === false ) {
 634                         $this->showMissingRevision();
 635
 636                         return false;
 637                 } else {
 638                         $this->showDiffStyle();
 639                         $this->getOutput()->addHTML( $diff );
 640
 641                         return true;
 642                 }
 643         }
 644
 645         /**
 646          * Add style sheets and supporting JS for diff display.
 647          */
 648         public function showDiffStyle() {
 649                 $this->getOutput()->addModuleStyles( 'mediawiki.action.history.diff' );
 650         }
 651
 652         /**
 653          * Get complete diff table, including header
 654          *
 655          * @param string|bool $otitle Header for old text or false
 656          * @param string|bool $ntitle Header for new text or false
 657          * @param string $notice HTML between diff header and body
 658          *
 659          * @return mixed
 660          */
 661         public function getDiff( $otitle, $ntitle, $notice = '' ) {
 662                 $body = $this->getDiffBody();
 663                 if ( $body === false ) {
 664                         return false;
 665                 }
 666
 667                 $multi = $this->getMultiNotice();
 668                 // Display a message when the diff is empty
 669                 if ( $body === '' ) {
 670                         $notice .= '<div class="mw-diff-empty">' .
 671                                 $this->msg( 'diff-empty' )->parse() .
 672                                 "</div>\n";
 673                 }
 674
 675                 return $this->addHeader( $body, $otitle, $ntitle, $multi, $notice );
 676         }
 677
 678         /**
 679          * Get the diff table body, without header
 680          *
 681          * @return mixed (string/false)
 682          */
 683         public function getDiffBody() {
 684                 $this->mCacheHit = true;
 685                 // Check if the diff should be hidden from this user
 686                 if ( !$this->loadRevisionData() ) {
 687                         return false;
 688                 } elseif ( $this->mOldRev &&
 689                         !$this->mOldRev->userCan( Revision::DELETED_TEXT, $this->getUser() )
 690                 ) {
 691                         return false;
 692                 } elseif ( $this->mNewRev &&
 693                         !$this->mNewRev->userCan( Revision::DELETED_TEXT, $this->getUser() )
 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                         return '';
 702                 }
 703                 // Cacheable?
 704                 $key = false;
 705                 $cache = ObjectCache::getMainWANInstance();
 706                 if ( $this->mOldid && $this->mNewid ) {
 707                         $key = $this->getDiffBodyCacheKey();
 708
 709                         // Try cache
 710                         if ( !$this->mRefreshCache ) {
 711                                 $difftext = $cache->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                         return false;
 726                 }
 727
 728                 $difftext = $this->generateContentDiffBody( $this->mOldContent, $this->mNewContent );
 729
 730                 // Save to cache for 7 days
 731                 if ( !Hooks::run( 'AbortDiffCache', array( &$this ) ) ) {
 732                         wfIncrStats( 'diff_cache.uncacheable' );
 733                 } elseif ( $key !== false && $difftext !== false ) {
 734                         wfIncrStats( 'diff_cache.miss' );
 735                         $cache->set( $key, $difftext, 7 * 86400 );
 736                 } else {
 737                         wfIncrStats( 'diff_cache.uncacheable' );
 738                 }
 739                 // Replace line numbers with the text in the user's language
 740                 if ( $difftext !== false ) {
 741                         $difftext = $this->localiseLineNumbers( $difftext );
 742                 }
 743
 744                 return $difftext;
 745         }
 746
 747         /**
 748          * Returns the cache key for diff body text or content.
 749          *
 750          * @since 1.23
 751          *
 752          * @throws MWException
 753          * @return string
 754          */
 755         protected function getDiffBodyCacheKey() {
 756                 if ( !$this->mOldid || !$this->mNewid ) {
 757                         throw new MWException( 'mOldid and mNewid must be set to get diff cache key.' );
 758                 }
 759
 760                 return wfMemcKey( 'diff', 'version', MW_DIFF_VERSION,
 761                         'oldid', $this->mOldid, 'newid', $this->mNewid );
 762         }
 763
 764         /**
 765          * Generate a diff, no caching.
 766          *
 767          * This implementation uses generateTextDiffBody() to generate a diff based on the default
 768          * serialization of the given Content objects. This will fail if $old or $new are not
 769          * instances of TextContent.
 770          *
 771          * Subclasses may override this to provide a different rendering for the diff,
 772          * perhaps taking advantage of the content's native form. This is required for all content
 773          * models that are not text based.
 774          *
 775          * @since 1.21
 776          *
 777          * @param Content $old Old content
 778          * @param Content $new New content
 779          *
 780          * @throws MWException If old or new content is not an instance of TextContent.
 781          * @return bool|string
 782          */
 783         public function generateContentDiffBody( Content $old, Content $new ) {
 784                 if ( !( $old instanceof TextContent ) ) {
 785                         throw new MWException( "Diff not implemented for " . get_class( $old ) . "; " .
 786                                 "override generateContentDiffBody to fix this." );
 787                 }
 788
 789                 if ( !( $new instanceof TextContent ) ) {
 790                         throw new MWException( "Diff not implemented for " . get_class( $new ) . "; "
 791                                 . "override generateContentDiffBody to fix this." );
 792                 }
 793
 794                 $otext = $old->serialize();
 795                 $ntext = $new->serialize();
 796
 797                 return $this->generateTextDiffBody( $otext, $ntext );
 798         }
 799
 800         /**
 801          * Generate a diff, no caching
 802          *
 803          * @param string $otext Old text, must be already segmented
 804          * @param string $ntext New text, must be already segmented
 805          *
 806          * @return bool|string
 807          * @deprecated since 1.21, use generateContentDiffBody() instead!
 808          */
 809         public function generateDiffBody( $otext, $ntext ) {
 810                 ContentHandler::deprecated( __METHOD__, "1.21" );
 811
 812                 return $this->generateTextDiffBody( $otext, $ntext );
 813         }
 814
 815         /**
 816          * Generate a diff, no caching
 817          *
 818          * @todo move this to TextDifferenceEngine, make DifferenceEngine abstract. At some point.
 819          *
 820          * @param string $otext Old text, must be already segmented
 821          * @param string $ntext New text, must be already segmented
 822          *
 823          * @return bool|string
 824          */
 825         public function generateTextDiffBody( $otext, $ntext ) {
 826                 global $wgExternalDiffEngine, $wgContLang;
 827
 828                 $otext = str_replace( "\r\n", "\n", $otext );
 829                 $ntext = str_replace( "\r\n", "\n", $ntext );
 830
 831                 if ( $wgExternalDiffEngine == 'wikidiff' && function_exists( 'wikidiff_do_diff' ) ) {
 832                         # For historical reasons, external diff engine expects
 833                         # input text to be HTML-escaped already
 834                         $otext = htmlspecialchars( $wgContLang->segmentForDiff( $otext ) );
 835                         $ntext = htmlspecialchars( $wgContLang->segmentForDiff( $ntext ) );
 836
 837                         return $wgContLang->unsegmentForDiff( wikidiff_do_diff( $otext, $ntext, 2 ) ) .
 838                         $this->debug( 'wikidiff1' );
 839                 }
 840
 841                 if ( $wgExternalDiffEngine == 'wikidiff2' && function_exists( 'wikidiff2_do_diff' ) ) {
 842                         # Better external diff engine, the 2 may some day be dropped
 843                         # This one does the escaping and segmenting itself
 844                         $text = wikidiff2_do_diff( $otext, $ntext, 2 );
 845                         $text .= $this->debug( 'wikidiff2' );
 846
 847                         return $text;
 848                 }
 849                 if ( $wgExternalDiffEngine != 'wikidiff3' && $wgExternalDiffEngine !== false ) {
 850                         # Diff via the shell
 851                         $tmpDir = wfTempDir();
 852                         $tempName1 = tempnam( $tmpDir, 'diff_' );
 853                         $tempName2 = tempnam( $tmpDir, 'diff_' );
 854
 855                         $tempFile1 = fopen( $tempName1, "w" );
 856                         if ( !$tempFile1 ) {
 857                                 return false;
 858                         }
 859                         $tempFile2 = fopen( $tempName2, "w" );
 860                         if ( !$tempFile2 ) {
 861                                 return false;
 862                         }
 863                         fwrite( $tempFile1, $otext );
 864                         fwrite( $tempFile2, $ntext );
 865                         fclose( $tempFile1 );
 866                         fclose( $tempFile2 );
 867                         $cmd = wfEscapeShellArg( $wgExternalDiffEngine, $tempName1, $tempName2 );
 868                         $difftext = wfShellExec( $cmd );
 869                         $difftext .= $this->debug( "external $wgExternalDiffEngine" );
 870                         unlink( $tempName1 );
 871                         unlink( $tempName2 );
 872
 873                         return $difftext;
 874                 }
 875
 876                 # Native PHP diff
 877                 $ota = explode( "\n", $wgContLang->segmentForDiff( $otext ) );
 878                 $nta = explode( "\n", $wgContLang->segmentForDiff( $ntext ) );
 879                 $diffs = new Diff( $ota, $nta );
 880                 $formatter = new TableDiffFormatter();
 881                 $difftext = $wgContLang->unsegmentForDiff( $formatter->format( $diffs ) );
 882
 883                 return $difftext;
 884         }
 885
 886         /**
 887          * Generate a debug comment indicating diff generating time,
 888          * server node, and generator backend.
 889          *
 890          * @param string $generator : What diff engine was used
 891          *
 892          * @return string
 893          */
 894         protected function debug( $generator = "internal" ) {
 895                 global $wgShowHostnames;
 896                 if ( !$this->enableDebugComment ) {
 897                         return '';
 898                 }
 899                 $data = array( $generator );
 900                 if ( $wgShowHostnames ) {
 901                         $data[] = wfHostname();
 902                 }
 903                 $data[] = wfTimestamp( TS_DB );
 904
 905                 return "<!-- diff generator: " .
 906                         implode( " ", array_map( "htmlspecialchars", $data ) ) .
 907                         " -->\n";
 908         }
 909
 910         /**
 911          * Replace line numbers with the text in the user's language
 912          *
 913          * @param string $text
 914          *
 915          * @return mixed
 916          */
 917         public function localiseLineNumbers( $text ) {
 918                 return preg_replace_callback(
 919                         '/<!--LINE (\d+)-->/',
 920                         array( &$this, 'localiseLineNumbersCb' ),
 921                         $text
 922                 );
 923         }
 924
 925         public function localiseLineNumbersCb( $matches ) {
 926                 if ( $matches[1] === '1' && $this->mReducedLineNumbers ) {
 927                         return '';
 928                 }
 929
 930                 return $this->msg( 'lineno' )->numParams( $matches[1] )->escaped();
 931         }
 932
 933         /**
 934          * If there are revisions between the ones being compared, return a note saying so.
 935          *
 936          * @return string
 937          */
 938         public function getMultiNotice() {
 939                 if ( !is_object( $this->mOldRev ) || !is_object( $this->mNewRev ) ) {
 940                         return '';
 941                 } elseif ( !$this->mOldPage->equals( $this->mNewPage ) ) {
 942                         // Comparing two different pages? Count would be meaningless.
 943                         return '';
 944                 }
 945
 946                 if ( $this->mOldRev->getTimestamp() > $this->mNewRev->getTimestamp() ) {
 947                         $oldRev = $this->mNewRev; // flip
 948                         $newRev = $this->mOldRev; // flip
 949                 } else { // normal case
 950                         $oldRev = $this->mOldRev;
 951                         $newRev = $this->mNewRev;
 952                 }
 953
 954                 // Sanity: don't show the notice if too many rows must be scanned
 955                 // @todo show some special message for that case
 956                 $nEdits = $this->mNewPage->countRevisionsBetween( $oldRev, $newRev, 1000 );
 957                 if ( $nEdits > 0 && $nEdits <= 1000 ) {
 958                         $limit = 100; // use diff-multi-manyusers if too many users
 959                         $users = $this->mNewPage->getAuthorsBetween( $oldRev, $newRev, $limit );
 960                         $numUsers = count( $users );
 961
 962                         if ( $numUsers == 1 && $users[0] == $newRev->getUserText( Revision::RAW ) ) {
 963                                 $numUsers = 0; // special case to say "by the same user" instead of "by one other user"
 964                         }
 965
 966                         return self::intermediateEditsMsg( $nEdits, $numUsers, $limit );
 967                 }
 968
 969                 return ''; // nothing
 970         }
 971
 972         /**
 973          * Get a notice about how many intermediate edits and users there are
 974          *
 975          * @param int $numEdits
 976          * @param int $numUsers
 977          * @param int $limit
 978          *
 979          * @return string
 980          */
 981         public static function intermediateEditsMsg( $numEdits, $numUsers, $limit ) {
 982                 if ( $numUsers === 0 ) {
 983                         $msg = 'diff-multi-sameuser';
 984                 } elseif ( $numUsers > $limit ) {
 985                         $msg = 'diff-multi-manyusers';
 986                         $numUsers = $limit;
 987                 } else {
 988                         $msg = 'diff-multi-otherusers';
 989                 }
 990
 991                 return wfMessage( $msg )->numParams( $numEdits, $numUsers )->parse();
 992         }
 993
 994         /**
 995          * Get a header for a specified revision.
 996          *
 997          * @param Revision $rev
 998          * @param string $complete 'complete' to get the header wrapped depending
 999          *        the visibility of the revision and a link to edit the page.
1000          *
1001          * @return string HTML fragment
1002          */
1003         protected function getRevisionHeader( Revision $rev, $complete = '' ) {
1004                 $lang = $this->getLanguage();
1005                 $user = $this->getUser();
1006                 $revtimestamp = $rev->getTimestamp();
1007                 $timestamp = $lang->userTimeAndDate( $revtimestamp, $user );
1008                 $dateofrev = $lang->userDate( $revtimestamp, $user );
1009                 $timeofrev = $lang->userTime( $revtimestamp, $user );
1010
1011                 $header = $this->msg(
1012                         $rev->isCurrent() ? 'currentrev-asof' : 'revisionasof',
1013                         $timestamp,
1014                         $dateofrev,
1015                         $timeofrev
1016                 )->escaped();
1017
1018                 if ( $complete !== 'complete' ) {
1019                         return $header;
1020                 }
1021
1022                 $title = $rev->getTitle();
1023
1024                 $header = Linker::linkKnown( $title, $header, array(),
1025                         array( 'oldid' => $rev->getID() ) );
1026
1027                 if ( $rev->userCan( Revision::DELETED_TEXT, $user ) ) {
1028                         $editQuery = array( 'action' => 'edit' );
1029                         if ( !$rev->isCurrent() ) {
1030                                 $editQuery['oldid'] = $rev->getID();
1031                         }
1032
1033                         $key = $title->quickUserCan( 'edit', $user ) ? 'editold' : 'viewsourceold';
1034                         $msg = $this->msg( $key )->escaped();
1035                         $editLink = $this->msg( 'parentheses' )->rawParams(
1036                                 Linker::linkKnown( $title, $msg, array(), $editQuery ) )->escaped();
1037                         $header .= ' ' . Html::rawElement(
1038                                 'span',
1039                                 array( 'class' => 'mw-diff-edit' ),
1040                                 $editLink
1041                         );
1042                         if ( $rev->isDeleted( Revision::DELETED_TEXT ) ) {
1043                                 $header = Html::rawElement(
1044                                         'span',
1045                                         array( 'class' => 'history-deleted' ),
1046                                         $header
1047                                 );
1048                         }
1049                 } else {
1050                         $header = Html::rawElement( 'span', array( 'class' => 'history-deleted' ), $header );
1051                 }
1052
1053                 return $header;
1054         }
1055
1056         /**
1057          * Add the header to a diff body
1058          *
1059          * @param string $diff Diff body
1060          * @param string $otitle Old revision header
1061          * @param string $ntitle New revision header
1062          * @param string $multi Notice telling user that there are intermediate
1063          *   revisions between the ones being compared
1064          * @param string $notice Other notices, e.g. that user is viewing deleted content
1065          *
1066          * @return string
1067          */
1068         public function addHeader( $diff, $otitle, $ntitle, $multi = '', $notice = '' ) {
1069                 // shared.css sets diff in interface language/dir, but the actual content
1070                 // is often in a different language, mostly the page content language/dir
1071                 $tableClass = 'diff diff-contentalign-' . htmlspecialchars( $this->getDiffLang()->alignStart() );
1072                 $header = "<table class='$tableClass'>";
1073                 $userLang = htmlspecialchars( $this->getLanguage()->getHtmlCode() );
1074
1075                 if ( !$diff && !$otitle ) {
1076                         $header .= "
1077                         <tr style='vertical-align: top;' lang='{$userLang}'>
1078                         <td class='diff-ntitle'>{$ntitle}</td>
1079                         </tr>";
1080                         $multiColspan = 1;
1081                 } else {
1082                         if ( $diff ) { // Safari/Chrome show broken output if cols not used
1083                                 $header .= "
1084                                 <col class='diff-marker' />
1085                                 <col class='diff-content' />
1086                                 <col class='diff-marker' />
1087                                 <col class='diff-content' />";
1088                                 $colspan = 2;
1089                                 $multiColspan = 4;
1090                         } else {
1091                                 $colspan = 1;
1092                                 $multiColspan = 2;
1093                         }
1094                         if ( $otitle || $ntitle ) {
1095                                 $header .= "
1096                                 <tr style='vertical-align: top;' lang='{$userLang}'>
1097                                 <td colspan='$colspan' class='diff-otitle'>{$otitle}</td>
1098                                 <td colspan='$colspan' class='diff-ntitle'>{$ntitle}</td>
1099                                 </tr>";
1100                         }
1101                 }
1102
1103                 if ( $multi != '' ) {
1104                         $header .= "<tr><td colspan='{$multiColspan}' style='text-align: center;' " .
1105                                 "class='diff-multi' lang='{$userLang}'>{$multi}</td></tr>";
1106                 }
1107                 if ( $notice != '' ) {
1108                         $header .= "<tr><td colspan='{$multiColspan}' style='text-align: center;' " .
1109                                 "lang='{$userLang}'>{$notice}</td></tr>";
1110                 }
1111
1112                 return $header . $diff . "</table>";
1113         }
1114
1115         /**
1116          * Use specified text instead of loading from the database
1117          * @deprecated since 1.21, use setContent() instead.
1118          */
1119         public function setText( $oldText, $newText ) {
1120                 ContentHandler::deprecated( __METHOD__, "1.21" );
1121
1122                 $oldContent = ContentHandler::makeContent( $oldText, $this->getTitle() );
1123                 $newContent = ContentHandler::makeContent( $newText, $this->getTitle() );
1124
1125                 $this->setContent( $oldContent, $newContent );
1126         }
1127
1128         /**
1129          * Use specified text instead of loading from the database
1130          * @param Content $oldContent
1131          * @param Content $newContent
1132          * @since 1.21
1133          */
1134         public function setContent( Content $oldContent, Content $newContent ) {
1135                 $this->mOldContent = $oldContent;
1136                 $this->mNewContent = $newContent;
1137
1138                 $this->mTextLoaded = 2;
1139                 $this->mRevisionsLoaded = true;
1140         }
1141
1142         /**
1143          * Set the language in which the diff text is written
1144          * (Defaults to page content language).
1145          * @param Language|string $lang
1146          * @since 1.19
1147          */
1148         public function setTextLanguage( $lang ) {
1149                 $this->mDiffLang = wfGetLangObj( $lang );
1150         }
1151
1152         /**
1153          * Maps a revision pair definition as accepted by DifferenceEngine constructor
1154          * to a pair of actual integers representing revision ids.
1155          *
1156          * @param int $old Revision id, e.g. from URL parameter 'oldid'
1157          * @param int|string $new Revision id or strings 'next' or 'prev', e.g. from URL parameter 'diff'
1158          *
1159          * @return int[] List of two revision ids, older first, later second.
1160          *     Zero signifies invalid argument passed.
1161          *     false signifies that there is no previous/next revision ($old is the oldest/newest one).
1162          */
1163         public function mapDiffPrevNext( $old, $new ) {
1164                 if ( $new === 'prev' ) {
1165                         // Show diff between revision $old and the previous one. Get previous one from DB.
1166                         $newid = intval( $old );
1167                         $oldid = $this->getTitle()->getPreviousRevisionID( $newid );
1168                 } elseif ( $new === 'next' ) {
1169                         // Show diff between revision $old and the next one. Get next one from DB.
1170                         $oldid = intval( $old );
1171                         $newid = $this->getTitle()->getNextRevisionID( $oldid );
1172                 } else {
1173                         $oldid = intval( $old );
1174                         $newid = intval( $new );
1175                 }
1176
1177                 return array( $oldid, $newid );
1178         }
1179
1180         /**
1181          * Load revision IDs
1182          */
1183         private function loadRevisionIds() {
1184                 if ( $this->mRevisionsIdsLoaded ) {
1185                         return;
1186                 }
1187
1188                 $this->mRevisionsIdsLoaded = true;
1189
1190                 $old = $this->mOldid;
1191                 $new = $this->mNewid;
1192
1193                 list( $this->mOldid, $this->mNewid ) = self::mapDiffPrevNext( $old, $new );
1194                 if ( $new === 'next' && $this->mNewid === false ) {
1195                         # if no result, NewId points to the newest old revision. The only newer
1196                         # revision is cur, which is "0".
1197                         $this->mNewid = 0;
1198                 }
1199
1200                 Hooks::run(
1201                         'NewDifferenceEngine',
1202                         array( $this->getTitle(), &$this->mOldid, &$this->mNewid, $old, $new )
1203                 );
1204         }
1205
1206         /**
1207          * Load revision metadata for the specified articles. If newid is 0, then compare
1208          * the old article in oldid to the current article; if oldid is 0, then
1209          * compare the current article to the immediately previous one (ignoring the
1210          * value of newid).
1211          *
1212          * If oldid is false, leave the corresponding revision object set
1213          * to false. This is impossible via ordinary user input, and is provided for
1214          * API convenience.
1215          *
1216          * @return bool
1217          */
1218         public function loadRevisionData() {
1219                 if ( $this->mRevisionsLoaded ) {
1220                         return true;
1221                 }
1222
1223                 // Whether it succeeds or fails, we don't want to try again
1224                 $this->mRevisionsLoaded = true;
1225
1226                 $this->loadRevisionIds();
1227
1228                 // Load the new revision object
1229                 if ( $this->mNewid ) {
1230                         $this->mNewRev = Revision::newFromId( $this->mNewid );
1231                 } else {
1232                         $this->mNewRev = Revision::newFromTitle(
1233                                 $this->getTitle(),
1234                                 false,
1235                                 Revision::READ_NORMAL
1236                         );
1237                 }
1238
1239                 if ( !$this->mNewRev instanceof Revision ) {
1240                         return false;
1241                 }
1242
1243                 // Update the new revision ID in case it was 0 (makes life easier doing UI stuff)
1244                 $this->mNewid = $this->mNewRev->getId();
1245                 $this->mNewPage = $this->mNewRev->getTitle();
1246
1247                 // Load the old revision object
1248                 $this->mOldRev = false;
1249                 if ( $this->mOldid ) {
1250                         $this->mOldRev = Revision::newFromId( $this->mOldid );
1251                 } elseif ( $this->mOldid === 0 ) {
1252                         $rev = $this->mNewRev->getPrevious();
1253                         if ( $rev ) {
1254                                 $this->mOldid = $rev->getId();
1255                                 $this->mOldRev = $rev;
1256                         } else {
1257                                 // No previous revision; mark to show as first-version only.
1258                                 $this->mOldid = false;
1259                                 $this->mOldRev = false;
1260                         }
1261                 } /* elseif ( $this->mOldid === false ) leave mOldRev false; */
1262
1263                 if ( is_null( $this->mOldRev ) ) {
1264                         return false;
1265                 }
1266
1267                 if ( $this->mOldRev ) {
1268                         $this->mOldPage = $this->mOldRev->getTitle();
1269                 }
1270
1271                 // Load tags information for both revisions
1272                 $dbr = wfGetDB( DB_SLAVE );
1273                 if ( $this->mOldid !== false ) {
1274                         $this->mOldTags = $dbr->selectField(
1275                                 'tag_summary',
1276                                 'ts_tags',
1277                                 array( 'ts_rev_id' => $this->mOldid ),
1278                                 __METHOD__
1279                         );
1280                 } else {
1281                         $this->mOldTags = false;
1282                 }
1283                 $this->mNewTags = $dbr->selectField(
1284                         'tag_summary',
1285                         'ts_tags',
1286                         array( 'ts_rev_id' => $this->mNewid ),
1287                         __METHOD__
1288                 );
1289
1290                 return true;
1291         }
1292
1293         /**
1294          * Load the text of the revisions, as well as revision data.
1295          *
1296          * @return bool
1297          */
1298         public function loadText() {
1299                 if ( $this->mTextLoaded == 2 ) {
1300                         return true;
1301                 }
1302
1303                 // Whether it succeeds or fails, we don't want to try again
1304                 $this->mTextLoaded = 2;
1305
1306                 if ( !$this->loadRevisionData() ) {
1307                         return false;
1308                 }
1309
1310                 if ( $this->mOldRev ) {
1311                         $this->mOldContent = $this->mOldRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1312                         if ( $this->mOldContent === null ) {
1313                                 return false;
1314                         }
1315                 }
1316
1317                 if ( $this->mNewRev ) {
1318                         $this->mNewContent = $this->mNewRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1319                         if ( $this->mNewContent === null ) {
1320                                 return false;
1321                         }
1322                 }
1323
1324                 return true;
1325         }
1326
1327         /**
1328          * Load the text of the new revision, not the old one
1329          *
1330          * @return bool
1331          */
1332         public function loadNewText() {
1333                 if ( $this->mTextLoaded >= 1 ) {
1334                         return true;
1335                 }
1336
1337                 $this->mTextLoaded = 1;
1338
1339                 if ( !$this->loadRevisionData() ) {
1340                         return false;
1341                 }
1342
1343                 $this->mNewContent = $this->mNewRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1344
1345                 return true;
1346         }
1347
1348 }