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', array( $this->mNewRev, &$revisionTools, $this->mOldRev ) );
 392                 $formattedRevisionTools = array();
 393                 // Put each one in parentheses (poor man's button)
 394                 foreach ( $revisionTools as $key => $tool ) {
 395                         $toolClass = is_string( $key ) ? $key : 'mw-diff-tool';
 396                         $element = Html::rawElement(
 397                                 'span',
 398                                 array( 'class' => $toolClass ),
 399                                 $this->msg( 'parentheses' )->rawParams( $tool )->escaped()
 400                         );
 401                         $formattedRevisionTools[] = $element;
 402                 }
 403                 $newRevisionHeader = $this->getRevisionHeader( $this->mNewRev, 'complete' ) .
 404                         ' ' . implode( ' ', $formattedRevisionTools );
 405                 $newChangeTags = ChangeTags::formatSummaryRow( $this->mNewTags, 'diff' );
 406
 407                 $newHeader = '<div id="mw-diff-ntitle1"><strong>' . $newRevisionHeader . '</strong></div>' .
 408                         '<div id="mw-diff-ntitle2">' . Linker::revUserTools( $this->mNewRev, !$this->unhide ) .
 409                         " $rollback</div>" .
 410                         '<div id="mw-diff-ntitle3">' . $newminor .
 411                         Linker::revComment( $this->mNewRev, !$diffOnly, !$this->unhide ) . $rdel . '</div>' .
 412                         '<div id="mw-diff-ntitle5">' . $newChangeTags[0] . '</div>' .
 413                         '<div id="mw-diff-ntitle4">' . $nextlink . $this->markPatrolledLink() . '</div>';
 414
 415                 if ( $this->mNewRev->isDeleted( Revision::DELETED_TEXT ) ) {
 416                         $deleted = true; // new revisions text is hidden
 417                         if ( $this->mNewRev->isDeleted( Revision::DELETED_RESTRICTED ) ) {
 418                                 $suppressed = true; // also suppressed
 419                         }
 420                 }
 421
 422                 # If the diff cannot be shown due to a deleted revision, then output
 423                 # the diff header and links to unhide (if available)...
 424                 if ( $deleted && ( !$this->unhide || !$allowed ) ) {
 425                         $this->showDiffStyle();
 426                         $multi = $this->getMultiNotice();
 427                         $out->addHTML( $this->addHeader( '', $oldHeader, $newHeader, $multi ) );
 428                         if ( !$allowed ) {
 429                                 $msg = $suppressed ? 'rev-suppressed-no-diff' : 'rev-deleted-no-diff';
 430                                 # Give explanation for why revision is not visible
 431                                 $out->wrapWikiMsg( "<div id='mw-$msg' class='mw-warning plainlinks'>\n$1\n</div>\n",
 432                                         array( $msg ) );
 433                         } else {
 434                                 # Give explanation and add a link to view the diff...
 435                                 $query = $this->getRequest()->appendQueryValue( 'unhide', '1', true );
 436                                 $link = $this->getTitle()->getFullURL( $query );
 437                                 $msg = $suppressed ? 'rev-suppressed-unhide-diff' : 'rev-deleted-unhide-diff';
 438                                 $out->wrapWikiMsg(
 439                                         "<div id='mw-$msg' class='mw-warning plainlinks'>\n$1\n</div>\n",
 440                                         array( $msg, $link )
 441                                 );
 442                         }
 443                 # Otherwise, output a regular diff...
 444                 } else {
 445                         # Add deletion notice if the user is viewing deleted content
 446                         $notice = '';
 447                         if ( $deleted ) {
 448                                 $msg = $suppressed ? 'rev-suppressed-diff-view' : 'rev-deleted-diff-view';
 449                                 $notice = "<div id='mw-$msg' class='mw-warning plainlinks'>\n" .
 450                                         $this->msg( $msg )->parse() .
 451                                         "</div>\n";
 452                         }
 453                         $this->showDiff( $oldHeader, $newHeader, $notice );
 454                         if ( !$diffOnly ) {
 455                                 $this->renderNewRevision();
 456                         }
 457                 }
 458         }
 459
 460         /**
 461          * Get a link to mark the change as patrolled, or '' if there's either no
 462          * revision to patrol or the user is not allowed to to it.
 463          * Side effect: When the patrol link is build, this method will call
 464          * OutputPage::preventClickjacking() and load mediawiki.page.patrol.ajax.
 465          *
 466          * @return string
 467          */
 468         protected function markPatrolledLink() {
 469                 global $wgUseRCPatrol, $wgEnableAPI, $wgEnableWriteAPI;
 470                 $user = $this->getUser();
 471
 472                 if ( $this->mMarkPatrolledLink === null ) {
 473                         // Prepare a change patrol link, if applicable
 474                         if (
 475                                 // Is patrolling enabled and the user allowed to?
 476                                 $wgUseRCPatrol && $this->mNewPage->quickUserCan( 'patrol', $user ) &&
 477                                 // Only do this if the revision isn't more than 6 hours older
 478                                 // than the Max RC age (6h because the RC might not be cleaned out regularly)
 479                                 RecentChange::isInRCLifespan( $this->mNewRev->getTimestamp(), 21600 )
 480                         ) {
 481                                 // Look for an unpatrolled change corresponding to this diff
 482
 483                                 $db = wfGetDB( DB_SLAVE );
 484                                 $change = RecentChange::newFromConds(
 485                                         array(
 486                                                 'rc_timestamp' => $db->timestamp( $this->mNewRev->getTimestamp() ),
 487                                                 'rc_this_oldid' => $this->mNewid,
 488                                                 'rc_patrolled' => 0
 489                                         ),
 490                                         __METHOD__
 491                                 );
 492
 493                                 if ( $change && !$change->getPerformer()->equals( $user ) ) {
 494                                         $rcid = $change->getAttribute( 'rc_id' );
 495                                 } else {
 496                                         // None found or the page has been created by the current user.
 497                                         // If the user could patrol this it already would be patrolled
 498                                         $rcid = 0;
 499                                 }
 500                                 // Build the link
 501                                 if ( $rcid ) {
 502                                         $this->getOutput()->preventClickjacking();
 503                                         if ( $wgEnableAPI && $wgEnableWriteAPI
 504                                                 && $user->isAllowed( 'writeapi' )
 505                                         ) {
 506                                                 $this->getOutput()->addModules( 'mediawiki.page.patrol.ajax' );
 507                                         }
 508
 509                                         $token = $user->getEditToken( $rcid );
 510                                         $this->mMarkPatrolledLink = ' <span class="patrollink">[' . Linker::linkKnown(
 511                                                 $this->mNewPage,
 512                                                 $this->msg( 'markaspatrolleddiff' )->escaped(),
 513                                                 array(),
 514                                                 array(
 515                                                         'action' => 'markpatrolled',
 516                                                         'rcid' => $rcid,
 517                                                         'token' => $token,
 518                                                 )
 519                                         ) . ']</span>';
 520                                 } else {
 521                                         $this->mMarkPatrolledLink = '';
 522                                 }
 523                         } else {
 524                                 $this->mMarkPatrolledLink = '';
 525                         }
 526                 }
 527
 528                 return $this->mMarkPatrolledLink;
 529         }
 530
 531         /**
 532          * @param Revision $rev
 533          *
 534          * @return string
 535          */
 536         protected function revisionDeleteLink( $rev ) {
 537                 $link = Linker::getRevDeleteLink( $this->getUser(), $rev, $rev->getTitle() );
 538                 if ( $link !== '' ) {
 539                         $link = '&#160;&#160;&#160;' . $link . ' ';
 540                 }
 541
 542                 return $link;
 543         }
 544
 545         /**
 546          * Show the new revision of the page.
 547          */
 548         public function renderNewRevision() {
 549                 $out = $this->getOutput();
 550                 $revHeader = $this->getRevisionHeader( $this->mNewRev );
 551                 # Add "current version as of X" title
 552                 $out->addHTML( "<hr class='diff-hr' id='mw-oldid' />
 553                 <h2 class='diff-currentversion-title'>{$revHeader}</h2>\n" );
 554                 # Page content may be handled by a hooked call instead...
 555                 # @codingStandardsIgnoreStart Ignoring long lines.
 556                 if ( Hooks::run( 'ArticleContentOnDiff', array( $this, $out ) ) ) {
 557                         $this->loadNewText();
 558                         $out->setRevisionId( $this->mNewid );
 559                         $out->setRevisionTimestamp( $this->mNewRev->getTimestamp() );
 560                         $out->setArticleFlag( true );
 561
 562                         // NOTE: only needed for B/C: custom rendering of JS/CSS via hook
 563                         if ( $this->mNewPage->isCssJsSubpage() || $this->mNewPage->isCssOrJsPage() ) {
 564                                 // This needs to be synchronised with Article::showCssOrJsPage(), which sucks
 565                                 // Give hooks a chance to customise the output
 566                                 // @todo standardize this crap into one function
 567                                 if ( ContentHandler::runLegacyHooks( 'ShowRawCssJs', array( $this->mNewContent, $this->mNewPage, $out ) ) ) {
 568                                         // NOTE: deprecated hook, B/C only
 569                                         // use the content object's own rendering
 570                                         $cnt = $this->mNewRev->getContent();
 571                                         $po = $cnt ? $cnt->getParserOutput( $this->mNewRev->getTitle(), $this->mNewRev->getId() ) : null;
 572                                         if ( $po ) {
 573                                                 $out->addParserOutputContent( $po );
 574                                         }
 575                                 }
 576                         } elseif ( !Hooks::run( 'ArticleContentViewCustom', array( $this->mNewContent, $this->mNewPage, $out ) ) ) {
 577                                 // Handled by extension
 578                         } elseif ( !ContentHandler::runLegacyHooks( 'ArticleViewCustom', array( $this->mNewContent, $this->mNewPage, $out ) ) ) {
 579                                 // NOTE: deprecated hook, B/C only
 580                                 // Handled by extension
 581                         } else {
 582                                 // Normal page
 583                                 if ( $this->getTitle()->equals( $this->mNewPage ) ) {
 584                                         // If the Title stored in the context is the same as the one
 585                                         // of the new revision, we can use its associated WikiPage
 586                                         // object.
 587                                         $wikiPage = $this->getWikiPage();
 588                                 } else {
 589                                         // Otherwise we need to create our own WikiPage object
 590                                         $wikiPage = WikiPage::factory( $this->mNewPage );
 591                                 }
 592
 593                                 $parserOutput = $this->getParserOutput( $wikiPage, $this->mNewRev );
 594
 595                                 # WikiPage::getParserOutput() should not return false, but just in case
 596                                 if ( $parserOutput ) {
 597                                         $out->addParserOutput( $parserOutput );
 598                                 }
 599                         }
 600                 }
 601                 # @codingStandardsIgnoreEnd
 602
 603                 # Add redundant patrol link on bottom...
 604                 $out->addHTML( $this->markPatrolledLink() );
 605
 606         }
 607
 608         protected function getParserOutput( WikiPage $page, Revision $rev ) {
 609                 $parserOptions = $page->makeParserOptions( $this->getContext() );
 610
 611                 if ( !$rev->isCurrent() || !$rev->getTitle()->quickUserCan( 'edit', $this->getUser() ) ) {
 612                         $parserOptions->setEditSection( false );
 613                 }
 614
 615                 $parserOutput = $page->getParserOutput( $parserOptions, $rev->getId() );
 616
 617                 return $parserOutput;
 618         }
 619
 620         /**
 621          * Get the diff text, send it to the OutputPage object
 622          * Returns false if the diff could not be generated, otherwise returns true
 623          *
 624          * @param string|bool $otitle Header for old text or false
 625          * @param string|bool $ntitle Header for new text or false
 626          * @param string $notice HTML between diff header and body
 627          *
 628          * @return bool
 629          */
 630         public function showDiff( $otitle, $ntitle, $notice = '' ) {
 631                 $diff = $this->getDiff( $otitle, $ntitle, $notice );
 632                 if ( $diff === false ) {
 633                         $this->showMissingRevision();
 634
 635                         return false;
 636                 } else {
 637                         $this->showDiffStyle();
 638                         $this->getOutput()->addHTML( $diff );
 639
 640                         return true;
 641                 }
 642         }
 643
 644         /**
 645          * Add style sheets and supporting JS for diff display.
 646          */
 647         public function showDiffStyle() {
 648                 $this->getOutput()->addModuleStyles( 'mediawiki.action.history.diff' );
 649         }
 650
 651         /**
 652          * Get complete diff table, including header
 653          *
 654          * @param string|bool $otitle Header for old text or false
 655          * @param string|bool $ntitle Header for new text or false
 656          * @param string $notice HTML between diff header and body
 657          *
 658          * @return mixed
 659          */
 660         public function getDiff( $otitle, $ntitle, $notice = '' ) {
 661                 $body = $this->getDiffBody();
 662                 if ( $body === false ) {
 663                         return false;
 664                 }
 665
 666                 $multi = $this->getMultiNotice();
 667                 // Display a message when the diff is empty
 668                 if ( $body === '' ) {
 669                         $notice .= '<div class="mw-diff-empty">' .
 670                                 $this->msg( 'diff-empty' )->parse() .
 671                                 "</div>\n";
 672                 }
 673
 674                 return $this->addHeader( $body, $otitle, $ntitle, $multi, $notice );
 675         }
 676
 677         /**
 678          * Get the diff table body, without header
 679          *
 680          * @return mixed (string/false)
 681          */
 682         public function getDiffBody() {
 683                 $this->mCacheHit = true;
 684                 // Check if the diff should be hidden from this user
 685                 if ( !$this->loadRevisionData() ) {
 686                         return false;
 687                 } elseif ( $this->mOldRev &&
 688                         !$this->mOldRev->userCan( Revision::DELETED_TEXT, $this->getUser() )
 689                 ) {
 690                         return false;
 691                 } elseif ( $this->mNewRev &&
 692                         !$this->mNewRev->userCan( Revision::DELETED_TEXT, $this->getUser() )
 693                 ) {
 694                         return false;
 695                 }
 696                 // Short-circuit
 697                 if ( $this->mOldRev === false || ( $this->mOldRev && $this->mNewRev
 698                         && $this->mOldRev->getID() == $this->mNewRev->getID() )
 699                 ) {
 700                         return '';
 701                 }
 702                 // Cacheable?
 703                 $key = false;
 704                 $cache = ObjectCache::getMainWANInstance();
 705                 if ( $this->mOldid && $this->mNewid ) {
 706                         $key = $this->getDiffBodyCacheKey();
 707
 708                         // Try cache
 709                         if ( !$this->mRefreshCache ) {
 710                                 $difftext = $cache->get( $key );
 711                                 if ( $difftext ) {
 712                                         wfIncrStats( 'diff_cache.hit' );
 713                                         $difftext = $this->localiseLineNumbers( $difftext );
 714                                         $difftext .= "\n<!-- diff cache key $key -->\n";
 715
 716                                         return $difftext;
 717                                 }
 718                         } // don't try to load but save the result
 719                 }
 720                 $this->mCacheHit = false;
 721
 722                 // Loadtext is permission safe, this just clears out the diff
 723                 if ( !$this->loadText() ) {
 724                         return false;
 725                 }
 726
 727                 $difftext = $this->generateContentDiffBody( $this->mOldContent, $this->mNewContent );
 728
 729                 // Save to cache for 7 days
 730                 if ( !Hooks::run( 'AbortDiffCache', array( &$this ) ) ) {
 731                         wfIncrStats( 'diff_cache.uncacheable' );
 732                 } elseif ( $key !== false && $difftext !== false ) {
 733                         wfIncrStats( 'diff_cache.miss' );
 734                         $cache->set( $key, $difftext, 7 * 86400 );
 735                 } else {
 736                         wfIncrStats( 'diff_cache.uncacheable' );
 737                 }
 738                 // Replace line numbers with the text in the user's language
 739                 if ( $difftext !== false ) {
 740                         $difftext = $this->localiseLineNumbers( $difftext );
 741                 }
 742
 743                 return $difftext;
 744         }
 745
 746         /**
 747          * Returns the cache key for diff body text or content.
 748          *
 749          * @since 1.23
 750          *
 751          * @throws MWException
 752          * @return string
 753          */
 754         protected function getDiffBodyCacheKey() {
 755                 if ( !$this->mOldid || !$this->mNewid ) {
 756                         throw new MWException( 'mOldid and mNewid must be set to get diff cache key.' );
 757                 }
 758
 759                 return wfMemcKey( 'diff', 'version', MW_DIFF_VERSION,
 760                         'oldid', $this->mOldid, 'newid', $this->mNewid );
 761         }
 762
 763         /**
 764          * Generate a diff, no caching.
 765          *
 766          * This implementation uses generateTextDiffBody() to generate a diff based on the default
 767          * serialization of the given Content objects. This will fail if $old or $new are not
 768          * instances of TextContent.
 769          *
 770          * Subclasses may override this to provide a different rendering for the diff,
 771          * perhaps taking advantage of the content's native form. This is required for all content
 772          * models that are not text based.
 773          *
 774          * @since 1.21
 775          *
 776          * @param Content $old Old content
 777          * @param Content $new New content
 778          *
 779          * @throws MWException If old or new content is not an instance of TextContent.
 780          * @return bool|string
 781          */
 782         public function generateContentDiffBody( Content $old, Content $new ) {
 783                 if ( !( $old instanceof TextContent ) ) {
 784                         throw new MWException( "Diff not implemented for " . get_class( $old ) . "; " .
 785                                 "override generateContentDiffBody to fix this." );
 786                 }
 787
 788                 if ( !( $new instanceof TextContent ) ) {
 789                         throw new MWException( "Diff not implemented for " . get_class( $new ) . "; "
 790                                 . "override generateContentDiffBody to fix this." );
 791                 }
 792
 793                 $otext = $old->serialize();
 794                 $ntext = $new->serialize();
 795
 796                 return $this->generateTextDiffBody( $otext, $ntext );
 797         }
 798
 799         /**
 800          * Generate a diff, no caching
 801          *
 802          * @param string $otext Old text, must be already segmented
 803          * @param string $ntext New text, must be already segmented
 804          *
 805          * @return bool|string
 806          * @deprecated since 1.21, use generateContentDiffBody() instead!
 807          */
 808         public function generateDiffBody( $otext, $ntext ) {
 809                 ContentHandler::deprecated( __METHOD__, "1.21" );
 810
 811                 return $this->generateTextDiffBody( $otext, $ntext );
 812         }
 813
 814         /**
 815          * Generate a diff, no caching
 816          *
 817          * @todo move this to TextDifferenceEngine, make DifferenceEngine abstract. At some point.
 818          *
 819          * @param string $otext Old text, must be already segmented
 820          * @param string $ntext New text, must be already segmented
 821          *
 822          * @return bool|string
 823          */
 824         public function generateTextDiffBody( $otext, $ntext ) {
 825                 global $wgExternalDiffEngine, $wgContLang;
 826
 827                 $otext = str_replace( "\r\n", "\n", $otext );
 828                 $ntext = str_replace( "\r\n", "\n", $ntext );
 829
 830                 if ( $wgExternalDiffEngine == 'wikidiff' && function_exists( 'wikidiff_do_diff' ) ) {
 831                         # For historical reasons, external diff engine expects
 832                         # input text to be HTML-escaped already
 833                         $otext = htmlspecialchars( $wgContLang->segmentForDiff( $otext ) );
 834                         $ntext = htmlspecialchars( $wgContLang->segmentForDiff( $ntext ) );
 835
 836                         return $wgContLang->unsegmentForDiff( wikidiff_do_diff( $otext, $ntext, 2 ) ) .
 837                         $this->debug( 'wikidiff1' );
 838                 }
 839
 840                 if ( $wgExternalDiffEngine == 'wikidiff2' && function_exists( 'wikidiff2_do_diff' ) ) {
 841                         # Better external diff engine, the 2 may some day be dropped
 842                         # This one does the escaping and segmenting itself
 843                         $text = wikidiff2_do_diff( $otext, $ntext, 2 );
 844                         $text .= $this->debug( 'wikidiff2' );
 845
 846                         return $text;
 847                 }
 848                 if ( $wgExternalDiffEngine != 'wikidiff3' && $wgExternalDiffEngine !== false ) {
 849                         # Diff via the shell
 850                         $tmpDir = wfTempDir();
 851                         $tempName1 = tempnam( $tmpDir, 'diff_' );
 852                         $tempName2 = tempnam( $tmpDir, 'diff_' );
 853
 854                         $tempFile1 = fopen( $tempName1, "w" );
 855                         if ( !$tempFile1 ) {
 856                                 return false;
 857                         }
 858                         $tempFile2 = fopen( $tempName2, "w" );
 859                         if ( !$tempFile2 ) {
 860                                 return false;
 861                         }
 862                         fwrite( $tempFile1, $otext );
 863                         fwrite( $tempFile2, $ntext );
 864                         fclose( $tempFile1 );
 865                         fclose( $tempFile2 );
 866                         $cmd = wfEscapeShellArg( $wgExternalDiffEngine, $tempName1, $tempName2 );
 867                         $difftext = wfShellExec( $cmd );
 868                         $difftext .= $this->debug( "external $wgExternalDiffEngine" );
 869                         unlink( $tempName1 );
 870                         unlink( $tempName2 );
 871
 872                         return $difftext;
 873                 }
 874
 875                 # Native PHP diff
 876                 $ota = explode( "\n", $wgContLang->segmentForDiff( $otext ) );
 877                 $nta = explode( "\n", $wgContLang->segmentForDiff( $ntext ) );
 878                 $diffs = new Diff( $ota, $nta );
 879                 $formatter = new TableDiffFormatter();
 880                 $difftext = $wgContLang->unsegmentForDiff( $formatter->format( $diffs ) );
 881
 882                 return $difftext;
 883         }
 884
 885         /**
 886          * Generate a debug comment indicating diff generating time,
 887          * server node, and generator backend.
 888          *
 889          * @param string $generator : What diff engine was used
 890          *
 891          * @return string
 892          */
 893         protected function debug( $generator = "internal" ) {
 894                 global $wgShowHostnames;
 895                 if ( !$this->enableDebugComment ) {
 896                         return '';
 897                 }
 898                 $data = array( $generator );
 899                 if ( $wgShowHostnames ) {
 900                         $data[] = wfHostname();
 901                 }
 902                 $data[] = wfTimestamp( TS_DB );
 903
 904                 return "<!-- diff generator: " .
 905                         implode( " ", array_map( "htmlspecialchars", $data ) ) .
 906                         " -->\n";
 907         }
 908
 909         /**
 910          * Replace line numbers with the text in the user's language
 911          *
 912          * @param string $text
 913          *
 914          * @return mixed
 915          */
 916         public function localiseLineNumbers( $text ) {
 917                 return preg_replace_callback(
 918                         '/<!--LINE (\d+)-->/',
 919                         array( &$this, 'localiseLineNumbersCb' ),
 920                         $text
 921                 );
 922         }
 923
 924         public function localiseLineNumbersCb( $matches ) {
 925                 if ( $matches[1] === '1' && $this->mReducedLineNumbers ) {
 926                         return '';
 927                 }
 928
 929                 return $this->msg( 'lineno' )->numParams( $matches[1] )->escaped();
 930         }
 931
 932         /**
 933          * If there are revisions between the ones being compared, return a note saying so.
 934          *
 935          * @return string
 936          */
 937         public function getMultiNotice() {
 938                 if ( !is_object( $this->mOldRev ) || !is_object( $this->mNewRev ) ) {
 939                         return '';
 940                 } elseif ( !$this->mOldPage->equals( $this->mNewPage ) ) {
 941                         // Comparing two different pages? Count would be meaningless.
 942                         return '';
 943                 }
 944
 945                 if ( $this->mOldRev->getTimestamp() > $this->mNewRev->getTimestamp() ) {
 946                         $oldRev = $this->mNewRev; // flip
 947                         $newRev = $this->mOldRev; // flip
 948                 } else { // normal case
 949                         $oldRev = $this->mOldRev;
 950                         $newRev = $this->mNewRev;
 951                 }
 952
 953                 // Sanity: don't show the notice if too many rows must be scanned
 954                 // @todo show some special message for that case
 955                 $nEdits = $this->mNewPage->countRevisionsBetween( $oldRev, $newRev, 1000 );
 956                 if ( $nEdits > 0 && $nEdits <= 1000 ) {
 957                         $limit = 100; // use diff-multi-manyusers if too many users
 958                         $users = $this->mNewPage->getAuthorsBetween( $oldRev, $newRev, $limit );
 959                         $numUsers = count( $users );
 960
 961                         if ( $numUsers == 1 && $users[0] == $newRev->getUserText( Revision::RAW ) ) {
 962                                 $numUsers = 0; // special case to say "by the same user" instead of "by one other user"
 963                         }
 964
 965                         return self::intermediateEditsMsg( $nEdits, $numUsers, $limit );
 966                 }
 967
 968                 return ''; // nothing
 969         }
 970
 971         /**
 972          * Get a notice about how many intermediate edits and users there are
 973          *
 974          * @param int $numEdits
 975          * @param int $numUsers
 976          * @param int $limit
 977          *
 978          * @return string
 979          */
 980         public static function intermediateEditsMsg( $numEdits, $numUsers, $limit ) {
 981                 if ( $numUsers === 0 ) {
 982                         $msg = 'diff-multi-sameuser';
 983                 } elseif ( $numUsers > $limit ) {
 984                         $msg = 'diff-multi-manyusers';
 985                         $numUsers = $limit;
 986                 } else {
 987                         $msg = 'diff-multi-otherusers';
 988                 }
 989
 990                 return wfMessage( $msg )->numParams( $numEdits, $numUsers )->parse();
 991         }
 992
 993         /**
 994          * Get a header for a specified revision.
 995          *
 996          * @param Revision $rev
 997          * @param string $complete 'complete' to get the header wrapped depending
 998          *        the visibility of the revision and a link to edit the page.
 999          *
1000          * @return string HTML fragment
1001          */
1002         protected function getRevisionHeader( Revision $rev, $complete = '' ) {
1003                 $lang = $this->getLanguage();
1004                 $user = $this->getUser();
1005                 $revtimestamp = $rev->getTimestamp();
1006                 $timestamp = $lang->userTimeAndDate( $revtimestamp, $user );
1007                 $dateofrev = $lang->userDate( $revtimestamp, $user );
1008                 $timeofrev = $lang->userTime( $revtimestamp, $user );
1009
1010                 $header = $this->msg(
1011                         $rev->isCurrent() ? 'currentrev-asof' : 'revisionasof',
1012                         $timestamp,
1013                         $dateofrev,
1014                         $timeofrev
1015                 )->escaped();
1016
1017                 if ( $complete !== 'complete' ) {
1018                         return $header;
1019                 }
1020
1021                 $title = $rev->getTitle();
1022
1023                 $header = Linker::linkKnown( $title, $header, array(),
1024                         array( 'oldid' => $rev->getID() ) );
1025
1026                 if ( $rev->userCan( Revision::DELETED_TEXT, $user ) ) {
1027                         $editQuery = array( 'action' => 'edit' );
1028                         if ( !$rev->isCurrent() ) {
1029                                 $editQuery['oldid'] = $rev->getID();
1030                         }
1031
1032                         $key = $title->quickUserCan( 'edit', $user ) ? 'editold' : 'viewsourceold';
1033                         $msg = $this->msg( $key )->escaped();
1034                         $editLink = $this->msg( 'parentheses' )->rawParams(
1035                                 Linker::linkKnown( $title, $msg, array(), $editQuery ) )->escaped();
1036                         $header .= ' ' . Html::rawElement(
1037                                 'span',
1038                                 array( 'class' => 'mw-diff-edit' ),
1039                                 $editLink
1040                         );
1041                         if ( $rev->isDeleted( Revision::DELETED_TEXT ) ) {
1042                                 $header = Html::rawElement(
1043                                         'span',
1044                                         array( 'class' => 'history-deleted' ),
1045                                         $header
1046                                 );
1047                         }
1048                 } else {
1049                         $header = Html::rawElement( 'span', array( 'class' => 'history-deleted' ), $header );
1050                 }
1051
1052                 return $header;
1053         }
1054
1055         /**
1056          * Add the header to a diff body
1057          *
1058          * @param string $diff Diff body
1059          * @param string $otitle Old revision header
1060          * @param string $ntitle New revision header
1061          * @param string $multi Notice telling user that there are intermediate
1062          *   revisions between the ones being compared
1063          * @param string $notice Other notices, e.g. that user is viewing deleted content
1064          *
1065          * @return string
1066          */
1067         public function addHeader( $diff, $otitle, $ntitle, $multi = '', $notice = '' ) {
1068                 // shared.css sets diff in interface language/dir, but the actual content
1069                 // is often in a different language, mostly the page content language/dir
1070                 $tableClass = 'diff diff-contentalign-' . htmlspecialchars( $this->getDiffLang()->alignStart() );
1071                 $header = "<table class='$tableClass'>";
1072                 $userLang = htmlspecialchars( $this->getLanguage()->getHtmlCode() );
1073
1074                 if ( !$diff && !$otitle ) {
1075                         $header .= "
1076                         <tr style='vertical-align: top;' lang='{$userLang}'>
1077                         <td class='diff-ntitle'>{$ntitle}</td>
1078                         </tr>";
1079                         $multiColspan = 1;
1080                 } else {
1081                         if ( $diff ) { // Safari/Chrome show broken output if cols not used
1082                                 $header .= "
1083                                 <col class='diff-marker' />
1084                                 <col class='diff-content' />
1085                                 <col class='diff-marker' />
1086                                 <col class='diff-content' />";
1087                                 $colspan = 2;
1088                                 $multiColspan = 4;
1089                         } else {
1090                                 $colspan = 1;
1091                                 $multiColspan = 2;
1092                         }
1093                         if ( $otitle || $ntitle ) {
1094                                 $header .= "
1095                                 <tr style='vertical-align: top;' lang='{$userLang}'>
1096                                 <td colspan='$colspan' class='diff-otitle'>{$otitle}</td>
1097                                 <td colspan='$colspan' class='diff-ntitle'>{$ntitle}</td>
1098                                 </tr>";
1099                         }
1100                 }
1101
1102                 if ( $multi != '' ) {
1103                         $header .= "<tr><td colspan='{$multiColspan}' style='text-align: center;' " .
1104                                 "class='diff-multi' lang='{$userLang}'>{$multi}</td></tr>";
1105                 }
1106                 if ( $notice != '' ) {
1107                         $header .= "<tr><td colspan='{$multiColspan}' style='text-align: center;' " .
1108                                 "lang='{$userLang}'>{$notice}</td></tr>";
1109                 }
1110
1111                 return $header . $diff . "</table>";
1112         }
1113
1114         /**
1115          * Use specified text instead of loading from the database
1116          * @deprecated since 1.21, use setContent() instead.
1117          */
1118         public function setText( $oldText, $newText ) {
1119                 ContentHandler::deprecated( __METHOD__, "1.21" );
1120
1121                 $oldContent = ContentHandler::makeContent( $oldText, $this->getTitle() );
1122                 $newContent = ContentHandler::makeContent( $newText, $this->getTitle() );
1123
1124                 $this->setContent( $oldContent, $newContent );
1125         }
1126
1127         /**
1128          * Use specified text instead of loading from the database
1129          * @param Content $oldContent
1130          * @param Content $newContent
1131          * @since 1.21
1132          */
1133         public function setContent( Content $oldContent, Content $newContent ) {
1134                 $this->mOldContent = $oldContent;
1135                 $this->mNewContent = $newContent;
1136
1137                 $this->mTextLoaded = 2;
1138                 $this->mRevisionsLoaded = true;
1139         }
1140
1141         /**
1142          * Set the language in which the diff text is written
1143          * (Defaults to page content language).
1144          * @param Language|string $lang
1145          * @since 1.19
1146          */
1147         public function setTextLanguage( $lang ) {
1148                 $this->mDiffLang = wfGetLangObj( $lang );
1149         }
1150
1151         /**
1152          * Maps a revision pair definition as accepted by DifferenceEngine constructor
1153          * to a pair of actual integers representing revision ids.
1154          *
1155          * @param int $old Revision id, e.g. from URL parameter 'oldid'
1156          * @param int|string $new Revision id or strings 'next' or 'prev', e.g. from URL parameter 'diff'
1157          *
1158          * @return int[] List of two revision ids, older first, later second.
1159          *     Zero signifies invalid argument passed.
1160          *     false signifies that there is no previous/next revision ($old is the oldest/newest one).
1161          */
1162         public function mapDiffPrevNext( $old, $new ) {
1163                 if ( $new === 'prev' ) {
1164                         // Show diff between revision $old and the previous one. Get previous one from DB.
1165                         $newid = intval( $old );
1166                         $oldid = $this->getTitle()->getPreviousRevisionID( $newid );
1167                 } elseif ( $new === 'next' ) {
1168                         // Show diff between revision $old and the next one. Get next one from DB.
1169                         $oldid = intval( $old );
1170                         $newid = $this->getTitle()->getNextRevisionID( $oldid );
1171                 } else {
1172                         $oldid = intval( $old );
1173                         $newid = intval( $new );
1174                 }
1175
1176                 return array( $oldid, $newid );
1177         }
1178
1179         /**
1180          * Load revision IDs
1181          */
1182         private function loadRevisionIds() {
1183                 if ( $this->mRevisionsIdsLoaded ) {
1184                         return;
1185                 }
1186
1187                 $this->mRevisionsIdsLoaded = true;
1188
1189                 $old = $this->mOldid;
1190                 $new = $this->mNewid;
1191
1192                 list( $this->mOldid, $this->mNewid ) = self::mapDiffPrevNext( $old, $new );
1193                 if ( $new === 'next' && $this->mNewid === false ) {
1194                         # if no result, NewId points to the newest old revision. The only newer
1195                         # revision is cur, which is "0".
1196                         $this->mNewid = 0;
1197                 }
1198
1199                 Hooks::run(
1200                         'NewDifferenceEngine',
1201                         array( $this->getTitle(), &$this->mOldid, &$this->mNewid, $old, $new )
1202                 );
1203         }
1204
1205         /**
1206          * Load revision metadata for the specified articles. If newid is 0, then compare
1207          * the old article in oldid to the current article; if oldid is 0, then
1208          * compare the current article to the immediately previous one (ignoring the
1209          * value of newid).
1210          *
1211          * If oldid is false, leave the corresponding revision object set
1212          * to false. This is impossible via ordinary user input, and is provided for
1213          * API convenience.
1214          *
1215          * @return bool
1216          */
1217         public function loadRevisionData() {
1218                 if ( $this->mRevisionsLoaded ) {
1219                         return true;
1220                 }
1221
1222                 // Whether it succeeds or fails, we don't want to try again
1223                 $this->mRevisionsLoaded = true;
1224
1225                 $this->loadRevisionIds();
1226
1227                 // Load the new revision object
1228                 if ( $this->mNewid ) {
1229                         $this->mNewRev = Revision::newFromId( $this->mNewid );
1230                 } else {
1231                         $this->mNewRev = Revision::newFromTitle(
1232                                 $this->getTitle(),
1233                                 false,
1234                                 Revision::READ_NORMAL
1235                         );
1236                 }
1237
1238                 if ( !$this->mNewRev instanceof Revision ) {
1239                         return false;
1240                 }
1241
1242                 // Update the new revision ID in case it was 0 (makes life easier doing UI stuff)
1243                 $this->mNewid = $this->mNewRev->getId();
1244                 $this->mNewPage = $this->mNewRev->getTitle();
1245
1246                 // Load the old revision object
1247                 $this->mOldRev = false;
1248                 if ( $this->mOldid ) {
1249                         $this->mOldRev = Revision::newFromId( $this->mOldid );
1250                 } elseif ( $this->mOldid === 0 ) {
1251                         $rev = $this->mNewRev->getPrevious();
1252                         if ( $rev ) {
1253                                 $this->mOldid = $rev->getId();
1254                                 $this->mOldRev = $rev;
1255                         } else {
1256                                 // No previous revision; mark to show as first-version only.
1257                                 $this->mOldid = false;
1258                                 $this->mOldRev = false;
1259                         }
1260                 } /* elseif ( $this->mOldid === false ) leave mOldRev false; */
1261
1262                 if ( is_null( $this->mOldRev ) ) {
1263                         return false;
1264                 }
1265
1266                 if ( $this->mOldRev ) {
1267                         $this->mOldPage = $this->mOldRev->getTitle();
1268                 }
1269
1270                 // Load tags information for both revisions
1271                 $dbr = wfGetDB( DB_SLAVE );
1272                 if ( $this->mOldid !== false ) {
1273                         $this->mOldTags = $dbr->selectField(
1274                                 'tag_summary',
1275                                 'ts_tags',
1276                                 array( 'ts_rev_id' => $this->mOldid ),
1277                                 __METHOD__
1278                         );
1279                 } else {
1280                         $this->mOldTags = false;
1281                 }
1282                 $this->mNewTags = $dbr->selectField(
1283                         'tag_summary',
1284                         'ts_tags',
1285                         array( 'ts_rev_id' => $this->mNewid ),
1286                         __METHOD__
1287                 );
1288
1289                 return true;
1290         }
1291
1292         /**
1293          * Load the text of the revisions, as well as revision data.
1294          *
1295          * @return bool
1296          */
1297         public function loadText() {
1298                 if ( $this->mTextLoaded == 2 ) {
1299                         return true;
1300                 }
1301
1302                 // Whether it succeeds or fails, we don't want to try again
1303                 $this->mTextLoaded = 2;
1304
1305                 if ( !$this->loadRevisionData() ) {
1306                         return false;
1307                 }
1308
1309                 if ( $this->mOldRev ) {
1310                         $this->mOldContent = $this->mOldRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1311                         if ( $this->mOldContent === null ) {
1312                                 return false;
1313                         }
1314                 }
1315
1316                 if ( $this->mNewRev ) {
1317                         $this->mNewContent = $this->mNewRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1318                         if ( $this->mNewContent === null ) {
1319                                 return false;
1320                         }
1321                 }
1322
1323                 return true;
1324         }
1325
1326         /**
1327          * Load the text of the new revision, not the old one
1328          *
1329          * @return bool
1330          */
1331         public function loadNewText() {
1332                 if ( $this->mTextLoaded >= 1 ) {
1333                         return true;
1334                 }
1335
1336                 $this->mTextLoaded = 1;
1337
1338                 if ( !$this->loadRevisionData() ) {
1339                         return false;
1340                 }
1341
1342                 $this->mNewContent = $this->mNewRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1343
1344                 return true;
1345         }
1346
1347 }