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         /** @var int */
  38         public $mOldid;
  39
  40         /** @var int */
  41         public $mNewid;
  42
  43         private $mOldTags;
  44         private $mNewTags;
  45
  46         /** @var Content */
  47         public $mOldContent;
  48
  49         /** @var Content */
  50         public $mNewContent;
  51
  52         /** @var Language */
  53         protected $mDiffLang;
  54
  55         /** @var  Title */
  56         public $mOldPage;
  57
  58         /** @var  Title */
  59         public $mNewPage;
  60
  61         /** @var Revision */
  62         public $mOldRev;
  63
  64         /** @var  Revision */
  65         public $mNewRev;
  66
  67         /** @var bool Have the revisions IDs been loaded */
  68         private $mRevisionsIdsLoaded = false;
  69
  70         /** @var bool Have the revisions been loaded */
  71         public $mRevisionsLoaded = false;
  72
  73         /** @var int How many text blobs have been loaded, 0, 1 or 2? */
  74         public $mTextLoaded = 0;
  75
  76         /** @var bool Was the diff fetched from cache? */
  77         public $mCacheHit = false;
  78
  79         /**
  80          * Set this to true to add debug info to the HTML output.
  81          * Warning: this may cause RSS readers to spuriously mark articles as "new"
  82          * (bug 20601)
  83          */
  84         public $enableDebugComment = false;
  85
  86         /** @var bool  If true, line X is not displayed when X is 1, for example
  87          *    to increase readability and conserve space with many small diffs.
  88          */
  89         protected $mReducedLineNumbers = false;
  90
  91         /** @var string Link to action=markpatrolled  */
  92         protected $mMarkPatrolledLink = null;
  93
  94         /** @var bool Show rev_deleted content if allowed */
  95         protected $unhide = false;
  96         /**#@-*/
  97
  98         /**
  99          * Constructor
 100          * @param $context IContextSource context to use, anything else will be ignored
 101          * @param $old Integer old ID we want to show and diff with.
 102          * @param $new String|int either revision ID or 'prev' or 'next'. Default: 0.
 103          * @param $rcid Integer Deprecated, no longer used!
 104          * @param $refreshCache boolean If set, refreshes the diff cache
 105          * @param $unhide boolean If set, allow viewing deleted revs
 106          */
 107         function __construct( $context = null, $old = 0, $new = 0, $rcid = 0,
 108                 $refreshCache = false, $unhide = false
 109         ) {
 110                 if ( $context instanceof IContextSource ) {
 111                         $this->setContext( $context );
 112                 }
 113
 114                 wfDebug( "DifferenceEngine old '$old' new '$new' rcid '$rcid'\n" );
 115
 116                 $this->mOldid = $old;
 117                 $this->mNewid = $new;
 118                 $this->mRefreshCache = $refreshCache;
 119                 $this->unhide = $unhide;
 120         }
 121
 122         /**
 123          * @param $value bool
 124          */
 125         function setReducedLineNumbers( $value = true ) {
 126                 $this->mReducedLineNumbers = $value;
 127         }
 128
 129         /**
 130          * @return Language
 131          */
 132         function getDiffLang() {
 133                 if ( $this->mDiffLang === null ) {
 134                         # Default language in which the diff text is written.
 135                         $this->mDiffLang = $this->getTitle()->getPageLanguage();
 136                 }
 137
 138                 return $this->mDiffLang;
 139         }
 140
 141         /**
 142          * @return bool
 143          */
 144         function wasCacheHit() {
 145                 return $this->mCacheHit;
 146         }
 147
 148         /**
 149          * @return int
 150          */
 151         function getOldid() {
 152                 $this->loadRevisionIds();
 153
 154                 return $this->mOldid;
 155         }
 156
 157         /**
 158          * @return Bool|int
 159          */
 160         function getNewid() {
 161                 $this->loadRevisionIds();
 162
 163                 return $this->mNewid;
 164         }
 165
 166         /**
 167          * Look up a special:Undelete link to the given deleted revision id,
 168          * as a workaround for being unable to load deleted diffs in currently.
 169          *
 170          * @param int $id revision ID
 171          * @return mixed URL or false
 172          */
 173         function deletedLink( $id ) {
 174                 if ( $this->getUser()->isAllowed( 'deletedhistory' ) ) {
 175                         $dbr = wfGetDB( DB_SLAVE );
 176                         $row = $dbr->selectRow( 'archive', '*',
 177                                 array( 'ar_rev_id' => $id ),
 178                                 __METHOD__ );
 179                         if ( $row ) {
 180                                 $rev = Revision::newFromArchiveRow( $row );
 181                                 $title = Title::makeTitleSafe( $row->ar_namespace, $row->ar_title );
 182
 183                                 return SpecialPage::getTitleFor( 'Undelete' )->getFullURL( array(
 184                                         'target' => $title->getPrefixedText(),
 185                                         'timestamp' => $rev->getTimestamp()
 186                                 ) );
 187                         }
 188                 }
 189
 190                 return false;
 191         }
 192
 193         /**
 194          * Build a wikitext link toward a deleted revision, if viewable.
 195          *
 196          * @param int $id revision ID
 197          * @return string wikitext fragment
 198          */
 199         function deletedIdMarker( $id ) {
 200                 $link = $this->deletedLink( $id );
 201                 if ( $link ) {
 202                         return "[$link $id]";
 203                 } else {
 204                         return $id;
 205                 }
 206         }
 207
 208         private function showMissingRevision() {
 209                 $out = $this->getOutput();
 210
 211                 $missing = array();
 212                 if ( $this->mOldRev === null ||
 213                         ( $this->mOldRev && $this->mOldContent === null )
 214                 ) {
 215                         $missing[] = $this->deletedIdMarker( $this->mOldid );
 216                 }
 217                 if ( $this->mNewRev === null ||
 218                         ( $this->mNewRev && $this->mNewContent === null )
 219                 ) {
 220                         $missing[] = $this->deletedIdMarker( $this->mNewid );
 221                 }
 222
 223                 $out->setPageTitle( $this->msg( 'errorpagetitle' ) );
 224                 $out->addWikiMsg( 'difference-missing-revision',
 225                         $this->getLanguage()->listToText( $missing ), count( $missing ) );
 226         }
 227
 228         function showDiffPage( $diffOnly = false ) {
 229                 wfProfileIn( __METHOD__ );
 230
 231                 # Allow frames except in certain special cases
 232                 $out = $this->getOutput();
 233                 $out->allowClickjacking();
 234                 $out->setRobotPolicy( 'noindex,nofollow' );
 235
 236                 if ( !$this->loadRevisionData() ) {
 237                         $this->showMissingRevision();
 238                         wfProfileOut( __METHOD__ );
 239
 240                         return;
 241                 }
 242
 243                 $user = $this->getUser();
 244                 $permErrors = $this->mNewPage->getUserPermissionsErrors( 'read', $user );
 245                 if ( $this->mOldPage ) { # mOldPage might not be set, see below.
 246                         $permErrors = wfMergeErrorArrays( $permErrors,
 247                                 $this->mOldPage->getUserPermissionsErrors( 'read', $user ) );
 248                 }
 249                 if ( count( $permErrors ) ) {
 250                         wfProfileOut( __METHOD__ );
 251                         throw new PermissionsError( 'read', $permErrors );
 252                 }
 253
 254                 $rollback = '';
 255
 256                 $query = array();
 257                 # Carry over 'diffonly' param via navigation links
 258                 if ( $diffOnly != $user->getBoolOption( 'diffonly' ) ) {
 259                         $query['diffonly'] = $diffOnly;
 260                 }
 261                 # Cascade unhide param in links for easy deletion browsing
 262                 if ( $this->unhide ) {
 263                         $query['unhide'] = 1;
 264                 }
 265
 266                 # Check if one of the revisions is deleted/suppressed
 267                 $deleted = $suppressed = false;
 268                 $allowed = $this->mNewRev->userCan( Revision::DELETED_TEXT, $user );
 269
 270                 $revisionTools = array();
 271
 272                 # mOldRev is false if the difference engine is called with a "vague" query for
 273                 # a diff between a version V and its previous version V' AND the version V
 274                 # is the first version of that article. In that case, V' does not exist.
 275                 if ( $this->mOldRev === false ) {
 276                         $out->setPageTitle( $this->msg( 'difference-title', $this->mNewPage->getPrefixedText() ) );
 277                         $samePage = true;
 278                         $oldHeader = '';
 279                 } else {
 280                         wfRunHooks( 'DiffViewHeader', array( $this, $this->mOldRev, $this->mNewRev ) );
 281
 282                         if ( $this->mNewPage->equals( $this->mOldPage ) ) {
 283                                 $out->setPageTitle( $this->msg( 'difference-title', $this->mNewPage->getPrefixedText() ) );
 284                                 $samePage = true;
 285                         } else {
 286                                 $out->setPageTitle( $this->msg( 'difference-title-multipage',
 287                                         $this->mOldPage->getPrefixedText(), $this->mNewPage->getPrefixedText() ) );
 288                                 $out->addSubtitle( $this->msg( 'difference-multipage' ) );
 289                                 $samePage = false;
 290                         }
 291
 292                         if ( $samePage && $this->mNewPage->quickUserCan( 'edit', $user ) ) {
 293                                 if ( $this->mNewRev->isCurrent() && $this->mNewPage->userCan( 'rollback', $user ) ) {
 294                                         $rollbackLink = Linker::generateRollback( $this->mNewRev, $this->getContext() );
 295                                         if ( $rollbackLink ) {
 296                                                 $out->preventClickjacking();
 297                                                 $rollback = '&#160;&#160;&#160;' . $rollbackLink;
 298                                         }
 299                                 }
 300
 301                                 if ( !$this->mOldRev->isDeleted( Revision::DELETED_TEXT ) &&
 302                                         !$this->mNewRev->isDeleted( Revision::DELETED_TEXT )
 303                                 ) {
 304                                         $undoLink = Html::element( 'a', array(
 305                                                         'href' => $this->mNewPage->getLocalURL( array(
 306                                                                 'action' => 'edit',
 307                                                                 'undoafter' => $this->mOldid,
 308                                                                 'undo' => $this->mNewid
 309                                                         ) ),
 310                                                         'title' => Linker::titleAttrib( 'undo' )
 311                                                 ),
 312                                                 $this->msg( 'editundo' )->text()
 313                                         );
 314                                         $revisionTools[] = $undoLink;
 315                                 }
 316                         }
 317
 318                         # Make "previous revision link"
 319                         if ( $samePage && $this->mOldRev->getPrevious() ) {
 320                                 $prevlink = Linker::linkKnown(
 321                                         $this->mOldPage,
 322                                         $this->msg( 'previousdiff' )->escaped(),
 323                                         array( 'id' => 'differences-prevlink' ),
 324                                         array( 'diff' => 'prev', 'oldid' => $this->mOldid ) + $query
 325                                 );
 326                         } else {
 327                                 $prevlink = '&#160;';
 328                         }
 329
 330                         if ( $this->mOldRev->isMinor() ) {
 331                                 $oldminor = ChangesList::flag( 'minor' );
 332                         } else {
 333                                 $oldminor = '';
 334                         }
 335
 336                         $ldel = $this->revisionDeleteLink( $this->mOldRev );
 337                         $oldRevisionHeader = $this->getRevisionHeader( $this->mOldRev, 'complete' );
 338                         $oldChangeTags = ChangeTags::formatSummaryRow( $this->mOldTags, 'diff' );
 339
 340                         $oldHeader = '<div id="mw-diff-otitle1"><strong>' . $oldRevisionHeader . '</strong></div>' .
 341                                 '<div id="mw-diff-otitle2">' .
 342                                 Linker::revUserTools( $this->mOldRev, !$this->unhide ) . '</div>' .
 343                                 '<div id="mw-diff-otitle3">' . $oldminor .
 344                                 Linker::revComment( $this->mOldRev, !$diffOnly, !$this->unhide ) . $ldel . '</div>' .
 345                                 '<div id="mw-diff-otitle5">' . $oldChangeTags[0] . '</div>' .
 346                                 '<div id="mw-diff-otitle4">' . $prevlink . '</div>';
 347
 348                         if ( $this->mOldRev->isDeleted( Revision::DELETED_TEXT ) ) {
 349                                 $deleted = true; // old revisions text is hidden
 350                                 if ( $this->mOldRev->isDeleted( Revision::DELETED_RESTRICTED ) ) {
 351                                         $suppressed = true; // also suppressed
 352                                 }
 353                         }
 354
 355                         # Check if this user can see the revisions
 356                         if ( !$this->mOldRev->userCan( Revision::DELETED_TEXT, $user ) ) {
 357                                 $allowed = false;
 358                         }
 359                 }
 360
 361                 # Make "next revision link"
 362                 # Skip next link on the top revision
 363                 if ( $samePage && !$this->mNewRev->isCurrent() ) {
 364                         $nextlink = Linker::linkKnown(
 365                                 $this->mNewPage,
 366                                 $this->msg( 'nextdiff' )->escaped(),
 367                                 array( 'id' => 'differences-nextlink' ),
 368                                 array( 'diff' => 'next', 'oldid' => $this->mNewid ) + $query
 369                         );
 370                 } else {
 371                         $nextlink = '&#160;';
 372                 }
 373
 374                 if ( $this->mNewRev->isMinor() ) {
 375                         $newminor = ChangesList::flag( 'minor' );
 376                 } else {
 377                         $newminor = '';
 378                 }
 379
 380                 # Handle RevisionDelete links...
 381                 $rdel = $this->revisionDeleteLink( $this->mNewRev );
 382
 383                 # Allow extensions to define their own revision tools
 384                 wfRunHooks( 'DiffRevisionTools', array( $this->mNewRev, &$revisionTools, $this->mOldRev ) );
 385                 $formattedRevisionTools = array();
 386                 // Put each one in parentheses (poor man's button)
 387                 foreach ( $revisionTools as $tool ) {
 388                         $formattedRevisionTools[] = $this->msg( 'parentheses' )->rawParams( $tool )->escaped();
 389                 }
 390                 $newRevisionHeader = $this->getRevisionHeader( $this->mNewRev, 'complete' ) .
 391                         ' ' . implode( ' ', $formattedRevisionTools );
 392                 $newChangeTags = ChangeTags::formatSummaryRow( $this->mNewTags, 'diff' );
 393
 394                 $newHeader = '<div id="mw-diff-ntitle1"><strong>' . $newRevisionHeader . '</strong></div>' .
 395                         '<div id="mw-diff-ntitle2">' . Linker::revUserTools( $this->mNewRev, !$this->unhide ) .
 396                         " $rollback</div>" .
 397                         '<div id="mw-diff-ntitle3">' . $newminor .
 398                         Linker::revComment( $this->mNewRev, !$diffOnly, !$this->unhide ) . $rdel . '</div>' .
 399                         '<div id="mw-diff-ntitle5">' . $newChangeTags[0] . '</div>' .
 400                         '<div id="mw-diff-ntitle4">' . $nextlink . $this->markPatrolledLink() . '</div>';
 401
 402                 if ( $this->mNewRev->isDeleted( Revision::DELETED_TEXT ) ) {
 403                         $deleted = true; // new revisions text is hidden
 404                         if ( $this->mNewRev->isDeleted( Revision::DELETED_RESTRICTED ) ) {
 405                                 $suppressed = true; // also suppressed
 406                         }
 407                 }
 408
 409                 # If the diff cannot be shown due to a deleted revision, then output
 410                 # the diff header and links to unhide (if available)...
 411                 if ( $deleted && ( !$this->unhide || !$allowed ) ) {
 412                         $this->showDiffStyle();
 413                         $multi = $this->getMultiNotice();
 414                         $out->addHTML( $this->addHeader( '', $oldHeader, $newHeader, $multi ) );
 415                         if ( !$allowed ) {
 416                                 $msg = $suppressed ? 'rev-suppressed-no-diff' : 'rev-deleted-no-diff';
 417                                 # Give explanation for why revision is not visible
 418                                 $out->wrapWikiMsg( "<div id='mw-$msg' class='mw-warning plainlinks'>\n$1\n</div>\n",
 419                                         array( $msg ) );
 420                         } else {
 421                                 # Give explanation and add a link to view the diff...
 422                                 $query = $this->getRequest()->appendQueryValue( 'unhide', '1', true );
 423                                 $link = $this->getTitle()->getFullURL( $query );
 424                                 $msg = $suppressed ? 'rev-suppressed-unhide-diff' : 'rev-deleted-unhide-diff';
 425                                 $out->wrapWikiMsg(
 426                                         "<div id='mw-$msg' class='mw-warning plainlinks'>\n$1\n</div>\n",
 427                                         array( $msg, $link )
 428                                 );
 429                         }
 430                 # Otherwise, output a regular diff...
 431                 } else {
 432                         # Add deletion notice if the user is viewing deleted content
 433                         $notice = '';
 434                         if ( $deleted ) {
 435                                 $msg = $suppressed ? 'rev-suppressed-diff-view' : 'rev-deleted-diff-view';
 436                                 $notice = "<div id='mw-$msg' class='mw-warning plainlinks'>\n" .
 437                                         $this->msg( $msg )->parse() .
 438                                         "</div>\n";
 439                         }
 440                         $this->showDiff( $oldHeader, $newHeader, $notice );
 441                         if ( !$diffOnly ) {
 442                                 $this->renderNewRevision();
 443                         }
 444                 }
 445                 wfProfileOut( __METHOD__ );
 446         }
 447
 448         /**
 449          * Get a link to mark the change as patrolled, or '' if there's either no
 450          * revision to patrol or the user is not allowed to to it.
 451          * Side effect: When the patrol link is build, this method will call
 452          * OutputPage::preventClickjacking() and load mediawiki.page.patrol.ajax.
 453          *
 454          * @return String
 455          */
 456         protected function markPatrolledLink() {
 457                 global $wgUseRCPatrol, $wgEnableAPI, $wgEnableWriteAPI;
 458                 $user = $this->getUser();
 459
 460                 if ( $this->mMarkPatrolledLink === null ) {
 461                         // Prepare a change patrol link, if applicable
 462                         if (
 463                                 // Is patrolling enabled and the user allowed to?
 464                                 $wgUseRCPatrol && $this->mNewPage->quickUserCan( 'patrol', $user ) &&
 465                                 // Only do this if the revision isn't more than 6 hours older
 466                                 // than the Max RC age (6h because the RC might not be cleaned out regularly)
 467                                 RecentChange::isInRCLifespan( $this->mNewRev->getTimestamp(), 21600 )
 468                         ) {
 469                                 // Look for an unpatrolled change corresponding to this diff
 470
 471                                 $db = wfGetDB( DB_SLAVE );
 472                                 $change = RecentChange::newFromConds(
 473                                         array(
 474                                                 'rc_timestamp' => $db->timestamp( $this->mNewRev->getTimestamp() ),
 475                                                 'rc_this_oldid' => $this->mNewid,
 476                                                 'rc_patrolled' => 0
 477                                         ),
 478                                         __METHOD__,
 479                                         array( 'USE INDEX' => 'rc_timestamp' )
 480                                 );
 481
 482                                 if ( $change && $change->getPerformer()->getName() !== $user->getName() ) {
 483                                         $rcid = $change->getAttribute( 'rc_id' );
 484                                 } else {
 485                                         // None found or the page has been created by the current user.
 486                                         // If the user could patrol this it already would be patrolled
 487                                         $rcid = 0;
 488                                 }
 489                                 // Build the link
 490                                 if ( $rcid ) {
 491                                         $this->getOutput()->preventClickjacking();
 492                                         if ( $wgEnableAPI && $wgEnableWriteAPI
 493                                                 && $user->isAllowed( 'writeapi' )
 494                                         ) {
 495                                                 $this->getOutput()->addModules( 'mediawiki.page.patrol.ajax' );
 496                                         }
 497
 498                                         $token = $user->getEditToken( $rcid );
 499                                         $this->mMarkPatrolledLink = ' <span class="patrollink">[' . Linker::linkKnown(
 500                                                 $this->mNewPage,
 501                                                 $this->msg( 'markaspatrolleddiff' )->escaped(),
 502                                                 array(),
 503                                                 array(
 504                                                         'action' => 'markpatrolled',
 505                                                         'rcid' => $rcid,
 506                                                         'token' => $token,
 507                                                 )
 508                                         ) . ']</span>';
 509                                 } else {
 510                                         $this->mMarkPatrolledLink = '';
 511                                 }
 512                         } else {
 513                                 $this->mMarkPatrolledLink = '';
 514                         }
 515                 }
 516
 517                 return $this->mMarkPatrolledLink;
 518         }
 519
 520         /**
 521          * @param $rev Revision
 522          * @return String
 523          */
 524         protected function revisionDeleteLink( $rev ) {
 525                 $link = Linker::getRevDeleteLink( $this->getUser(), $rev, $rev->getTitle() );
 526                 if ( $link !== '' ) {
 527                         $link = '&#160;&#160;&#160;' . $link . ' ';
 528                 }
 529
 530                 return $link;
 531         }
 532
 533         /**
 534          * Show the new revision of the page.
 535          */
 536         function renderNewRevision() {
 537                 wfProfileIn( __METHOD__ );
 538                 $out = $this->getOutput();
 539                 $revHeader = $this->getRevisionHeader( $this->mNewRev );
 540                 # Add "current version as of X" title
 541                 $out->addHTML( "<hr class='diff-hr' />
 542                 <h2 class='diff-currentversion-title'>{$revHeader}</h2>\n" );
 543                 # Page content may be handled by a hooked call instead...
 544                 # @codingStandardsIgnoreStart Ignoring long lines.
 545                 if ( wfRunHooks( 'ArticleContentOnDiff', array( $this, $out ) ) ) {
 546                         $this->loadNewText();
 547                         $out->setRevisionId( $this->mNewid );
 548                         $out->setRevisionTimestamp( $this->mNewRev->getTimestamp() );
 549                         $out->setArticleFlag( true );
 550
 551                         // NOTE: only needed for B/C: custom rendering of JS/CSS via hook
 552                         if ( $this->mNewPage->isCssJsSubpage() || $this->mNewPage->isCssOrJsPage() ) {
 553                                 // Stolen from Article::view --AG 2007-10-11
 554                                 // Give hooks a chance to customise the output
 555                                 // @todo standardize this crap into one function
 556                                 if ( ContentHandler::runLegacyHooks( 'ShowRawCssJs', array( $this->mNewContent, $this->mNewPage, $out ) ) ) {
 557                                         // NOTE: deprecated hook, B/C only
 558                                         // use the content object's own rendering
 559                                         $cnt = $this->mNewRev->getContent();
 560                                         $po = $cnt ? $cnt->getParserOutput( $this->mNewRev->getTitle(), $this->mNewRev->getId() ) : null;
 561                                         $txt = $po ? $po->getText() : '';
 562                                         $out->addHTML( $txt );
 563                                 }
 564                         } elseif ( !wfRunHooks( 'ArticleContentViewCustom', array( $this->mNewContent, $this->mNewPage, $out ) ) ) {
 565                                 // Handled by extension
 566                         } elseif ( !ContentHandler::runLegacyHooks( 'ArticleViewCustom', array( $this->mNewContent, $this->mNewPage, $out ) ) ) {
 567                                 // NOTE: deprecated hook, B/C only
 568                                 // Handled by extension
 569                         } else {
 570                                 // Normal page
 571                                 if ( $this->getTitle()->equals( $this->mNewPage ) ) {
 572                                         // If the Title stored in the context is the same as the one
 573                                         // of the new revision, we can use its associated WikiPage
 574                                         // object.
 575                                         $wikiPage = $this->getWikiPage();
 576                                 } else {
 577                                         // Otherwise we need to create our own WikiPage object
 578                                         $wikiPage = WikiPage::factory( $this->mNewPage );
 579                                 }
 580
 581                                 $parserOutput = $this->getParserOutput( $wikiPage, $this->mNewRev );
 582
 583                                 # WikiPage::getParserOutput() should not return false, but just in case
 584                                 if ( $parserOutput ) {
 585                                         $out->addParserOutput( $parserOutput );
 586                                 }
 587                         }
 588                 }
 589                 # @codingStandardsIgnoreEnd
 590
 591                 # Add redundant patrol link on bottom...
 592                 $out->addHTML( $this->markPatrolledLink() );
 593
 594                 wfProfileOut( __METHOD__ );
 595         }
 596
 597         protected function getParserOutput( WikiPage $page, Revision $rev ) {
 598                 $parserOptions = $page->makeParserOptions( $this->getContext() );
 599
 600                 if ( !$rev->isCurrent() || !$rev->getTitle()->quickUserCan( "edit" ) ) {
 601                         $parserOptions->setEditSection( false );
 602                 }
 603
 604                 $parserOutput = $page->getParserOutput( $parserOptions, $rev->getId() );
 605
 606                 return $parserOutput;
 607         }
 608
 609         /**
 610          * Get the diff text, send it to the OutputPage object
 611          * Returns false if the diff could not be generated, otherwise returns true
 612          *
 613          * @param string|bool $otitle Header for old text or false
 614          * @param string|bool $ntitle Header for new text or false
 615          * @param string $notice HTML between diff header and body
 616          *
 617          * @return bool
 618          */
 619         function showDiff( $otitle, $ntitle, $notice = '' ) {
 620                 $diff = $this->getDiff( $otitle, $ntitle, $notice );
 621                 if ( $diff === false ) {
 622                         $this->showMissingRevision();
 623
 624                         return false;
 625                 } else {
 626                         $this->showDiffStyle();
 627                         $this->getOutput()->addHTML( $diff );
 628
 629                         return true;
 630                 }
 631         }
 632
 633         /**
 634          * Add style sheets and supporting JS for diff display.
 635          */
 636         function showDiffStyle() {
 637                 $this->getOutput()->addModuleStyles( 'mediawiki.action.history.diff' );
 638         }
 639
 640         /**
 641          * Get complete diff table, including header
 642          *
 643          * @param string|bool $otitle Header for old text or false
 644          * @param string|bool $ntitle Header for new text or false
 645          * @param string $notice HTML between diff header and body
 646          * @return mixed
 647          */
 648         function getDiff( $otitle, $ntitle, $notice = '' ) {
 649                 $body = $this->getDiffBody();
 650                 if ( $body === false ) {
 651                         return false;
 652                 }
 653
 654                 $multi = $this->getMultiNotice();
 655                 // Display a message when the diff is empty
 656                 if ( $body === '' ) {
 657                         $notice .= '<div class="mw-diff-empty">' .
 658                                 $this->msg( 'diff-empty' )->parse() .
 659                                 "</div>\n";
 660                 }
 661
 662                 return $this->addHeader( $body, $otitle, $ntitle, $multi, $notice );
 663         }
 664
 665         /**
 666          * Get the diff table body, without header
 667          *
 668          * @return mixed (string/false)
 669          */
 670         public function getDiffBody() {
 671                 global $wgMemc;
 672                 wfProfileIn( __METHOD__ );
 673                 $this->mCacheHit = true;
 674                 // Check if the diff should be hidden from this user
 675                 if ( !$this->loadRevisionData() ) {
 676                         wfProfileOut( __METHOD__ );
 677
 678                         return false;
 679                 } elseif ( $this->mOldRev &&
 680                         !$this->mOldRev->userCan( Revision::DELETED_TEXT, $this->getUser() )
 681                 ) {
 682                         wfProfileOut( __METHOD__ );
 683
 684                         return false;
 685                 } elseif ( $this->mNewRev &&
 686                         !$this->mNewRev->userCan( Revision::DELETED_TEXT, $this->getUser() )
 687                 ) {
 688                         wfProfileOut( __METHOD__ );
 689
 690                         return false;
 691                 }
 692                 // Short-circuit
 693                 if ( $this->mOldRev === false || ( $this->mOldRev && $this->mNewRev
 694                         && $this->mOldRev->getID() == $this->mNewRev->getID() )
 695                 ) {
 696                         wfProfileOut( __METHOD__ );
 697
 698                         return '';
 699                 }
 700                 // Cacheable?
 701                 $key = false;
 702                 if ( $this->mOldid && $this->mNewid ) {
 703                         $key = $this->getDiffBodyCacheKey();
 704
 705                         // Try cache
 706                         if ( !$this->mRefreshCache ) {
 707                                 $difftext = $wgMemc->get( $key );
 708                                 if ( $difftext ) {
 709                                         wfIncrStats( 'diff_cache_hit' );
 710                                         $difftext = $this->localiseLineNumbers( $difftext );
 711                                         $difftext .= "\n<!-- diff cache key $key -->\n";
 712                                         wfProfileOut( __METHOD__ );
 713
 714                                         return $difftext;
 715                                 }
 716                         } // don't try to load but save the result
 717                 }
 718                 $this->mCacheHit = false;
 719
 720                 // Loadtext is permission safe, this just clears out the diff
 721                 if ( !$this->loadText() ) {
 722                         wfProfileOut( __METHOD__ );
 723
 724                         return false;
 725                 }
 726
 727                 $difftext = $this->generateContentDiffBody( $this->mOldContent, $this->mNewContent );
 728
 729                 // Save to cache for 7 days
 730                 if ( !wfRunHooks( 'AbortDiffCache', array( &$this ) ) ) {
 731                         wfIncrStats( 'diff_uncacheable' );
 732                 } elseif ( $key !== false && $difftext !== false ) {
 733                         wfIncrStats( 'diff_cache_miss' );
 734                         $wgMemc->set( $key, $difftext, 7 * 86400 );
 735                 } else {
 736                         wfIncrStats( 'diff_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                 wfProfileOut( __METHOD__ );
 743
 744                 return $difftext;
 745         }
 746
 747         /**
 748          * Returns the cache key for diff body text or content.
 749          *
 750          * @return string
 751          * @since 1.23
 752          * @throws MWException
 753          */
 754         protected function getDiffBodyCacheKey() {
 755                 if ( !$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          * @param $old Content: old content
 775          * @param $new Content: new content
 776          *
 777          * @return bool|string
 778          * @since 1.21
 779          * @throws MWException if $old or $new are not instances of TextContent.
 780          */
 781         function generateContentDiffBody( Content $old, Content $new ) {
 782                 if ( !( $old instanceof TextContent ) ) {
 783                         throw new MWException( "Diff not implemented for " . get_class( $old ) . "; " .
 784                                 "override generateContentDiffBody to fix this." );
 785                 }
 786
 787                 if ( !( $new instanceof TextContent ) ) {
 788                         throw new MWException( "Diff not implemented for " . get_class( $new ) . "; "
 789                                 . "override generateContentDiffBody to fix this." );
 790                 }
 791
 792                 $otext = $old->serialize();
 793                 $ntext = $new->serialize();
 794
 795                 return $this->generateTextDiffBody( $otext, $ntext );
 796         }
 797
 798         /**
 799          * Generate a diff, no caching
 800          *
 801          * @param string $otext old text, must be already segmented
 802          * @param string $ntext new text, must be already segmented
 803          * @return bool|string
 804          * @deprecated since 1.21, use generateContentDiffBody() instead!
 805          */
 806         function generateDiffBody( $otext, $ntext ) {
 807                 ContentHandler::deprecated( __METHOD__, "1.21" );
 808
 809                 return $this->generateTextDiffBody( $otext, $ntext );
 810         }
 811
 812         /**
 813          * Generate a diff, no caching
 814          *
 815          * @todo move this to TextDifferenceEngine, make DifferenceEngine abstract. At some point.
 816          *
 817          * @param string $otext old text, must be already segmented
 818          * @param string $ntext new text, must be already segmented
 819          * @return bool|string
 820          */
 821         function generateTextDiffBody( $otext, $ntext ) {
 822                 global $wgExternalDiffEngine, $wgContLang;
 823
 824                 wfProfileIn( __METHOD__ );
 825
 826                 $otext = str_replace( "\r\n", "\n", $otext );
 827                 $ntext = str_replace( "\r\n", "\n", $ntext );
 828
 829                 if ( $wgExternalDiffEngine == 'wikidiff' && function_exists( 'wikidiff_do_diff' ) ) {
 830                         # For historical reasons, external diff engine expects
 831                         # input text to be HTML-escaped already
 832                         $otext = htmlspecialchars( $wgContLang->segmentForDiff( $otext ) );
 833                         $ntext = htmlspecialchars( $wgContLang->segmentForDiff( $ntext ) );
 834                         wfProfileOut( __METHOD__ );
 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                         wfProfileIn( 'wikidiff2_do_diff' );
 844                         $text = wikidiff2_do_diff( $otext, $ntext, 2 );
 845                         $text .= $this->debug( 'wikidiff2' );
 846                         wfProfileOut( 'wikidiff2_do_diff' );
 847                         wfProfileOut( __METHOD__ );
 848
 849                         return $text;
 850                 }
 851                 if ( $wgExternalDiffEngine != 'wikidiff3' && $wgExternalDiffEngine !== false ) {
 852                         # Diff via the shell
 853                         $tmpDir = wfTempDir();
 854                         $tempName1 = tempnam( $tmpDir, 'diff_' );
 855                         $tempName2 = tempnam( $tmpDir, 'diff_' );
 856
 857                         $tempFile1 = fopen( $tempName1, "w" );
 858                         if ( !$tempFile1 ) {
 859                                 wfProfileOut( __METHOD__ );
 860
 861                                 return false;
 862                         }
 863                         $tempFile2 = fopen( $tempName2, "w" );
 864                         if ( !$tempFile2 ) {
 865                                 wfProfileOut( __METHOD__ );
 866
 867                                 return false;
 868                         }
 869                         fwrite( $tempFile1, $otext );
 870                         fwrite( $tempFile2, $ntext );
 871                         fclose( $tempFile1 );
 872                         fclose( $tempFile2 );
 873                         $cmd = wfEscapeShellArg( $wgExternalDiffEngine, $tempName1, $tempName2 );
 874                         wfProfileIn( __METHOD__ . "-shellexec" );
 875                         $difftext = wfShellExec( $cmd );
 876                         $difftext .= $this->debug( "external $wgExternalDiffEngine" );
 877                         wfProfileOut( __METHOD__ . "-shellexec" );
 878                         unlink( $tempName1 );
 879                         unlink( $tempName2 );
 880                         wfProfileOut( __METHOD__ );
 881
 882                         return $difftext;
 883                 }
 884
 885                 # Native PHP diff
 886                 $ota = explode( "\n", $wgContLang->segmentForDiff( $otext ) );
 887                 $nta = explode( "\n", $wgContLang->segmentForDiff( $ntext ) );
 888                 $diffs = new Diff( $ota, $nta );
 889                 $formatter = new TableDiffFormatter();
 890                 $difftext = $wgContLang->unsegmentForDiff( $formatter->format( $diffs ) ) .
 891                         wfProfileOut( __METHOD__ );
 892
 893                 return $difftext;
 894         }
 895
 896         /**
 897          * Generate a debug comment indicating diff generating time,
 898          * server node, and generator backend.
 899          *
 900          * @param String $generator : What diff engine was used
 901          *
 902          * @return string
 903          */
 904         protected function debug( $generator = "internal" ) {
 905                 global $wgShowHostnames;
 906                 if ( !$this->enableDebugComment ) {
 907                         return '';
 908                 }
 909                 $data = array( $generator );
 910                 if ( $wgShowHostnames ) {
 911                         $data[] = wfHostname();
 912                 }
 913                 $data[] = wfTimestamp( TS_DB );
 914
 915                 return "<!-- diff generator: " .
 916                         implode( " ", array_map( "htmlspecialchars", $data ) ) .
 917                         " -->\n";
 918         }
 919
 920         /**
 921          * Replace line numbers with the text in the user's language
 922          *
 923          * @param String $text
 924          *
 925          * @return mixed
 926          */
 927         function localiseLineNumbers( $text ) {
 928                 return preg_replace_callback(
 929                         '/<!--LINE (\d+)-->/',
 930                         array( &$this, 'localiseLineNumbersCb' ),
 931                         $text
 932                 );
 933         }
 934
 935         function localiseLineNumbersCb( $matches ) {
 936                 if ( $matches[1] === '1' && $this->mReducedLineNumbers ) {
 937                         return '';
 938                 }
 939
 940                 return $this->msg( 'lineno' )->numParams( $matches[1] )->escaped();
 941         }
 942
 943         /**
 944          * If there are revisions between the ones being compared, return a note saying so.
 945          * @return string
 946          */
 947         function getMultiNotice() {
 948                 if ( !is_object( $this->mOldRev ) || !is_object( $this->mNewRev ) ) {
 949                         return '';
 950                 } elseif ( !$this->mOldPage->equals( $this->mNewPage ) ) {
 951                         // Comparing two different pages? Count would be meaningless.
 952                         return '';
 953                 }
 954
 955                 if ( $this->mOldRev->getTimestamp() > $this->mNewRev->getTimestamp() ) {
 956                         $oldRev = $this->mNewRev; // flip
 957                         $newRev = $this->mOldRev; // flip
 958                 } else { // normal case
 959                         $oldRev = $this->mOldRev;
 960                         $newRev = $this->mNewRev;
 961                 }
 962
 963                 $nEdits = $this->mNewPage->countRevisionsBetween( $oldRev, $newRev );
 964                 if ( $nEdits > 0 ) {
 965                         $limit = 100; // use diff-multi-manyusers if too many users
 966                         $numUsers = $this->mNewPage->countAuthorsBetween( $oldRev, $newRev, $limit );
 967
 968                         return self::intermediateEditsMsg( $nEdits, $numUsers, $limit );
 969                 }
 970
 971                 return ''; // nothing
 972         }
 973
 974         /**
 975          * Get a notice about how many intermediate edits and users there are
 976          * @param $numEdits int
 977          * @param $numUsers int
 978          * @param $limit int
 979          * @return string
 980          */
 981         public static function intermediateEditsMsg( $numEdits, $numUsers, $limit ) {
 982                 if ( $numUsers > $limit ) {
 983                         $msg = 'diff-multi-manyusers';
 984                         $numUsers = $limit;
 985                 } else {
 986                         $msg = 'diff-multi';
 987                 }
 988
 989                 return wfMessage( $msg )->numParams( $numEdits, $numUsers )->parse();
 990         }
 991
 992         /**
 993          * Get a header for a specified revision.
 994          *
 995          * @param $rev Revision
 996          * @param string $complete 'complete' to get the header wrapped depending
 997          *        the visibility of the revision and a link to edit the page.
 998          * @return String HTML fragment
 999          */
1000         protected function getRevisionHeader( Revision $rev, $complete = '' ) {
1001                 $lang = $this->getLanguage();
1002                 $user = $this->getUser();
1003                 $revtimestamp = $rev->getTimestamp();
1004                 $timestamp = $lang->userTimeAndDate( $revtimestamp, $user );
1005                 $dateofrev = $lang->userDate( $revtimestamp, $user );
1006                 $timeofrev = $lang->userTime( $revtimestamp, $user );
1007
1008                 $header = $this->msg(
1009                         $rev->isCurrent() ? 'currentrev-asof' : 'revisionasof',
1010                         $timestamp,
1011                         $dateofrev,
1012                         $timeofrev
1013                 )->escaped();
1014
1015                 if ( $complete !== 'complete' ) {
1016                         return $header;
1017                 }
1018
1019                 $title = $rev->getTitle();
1020
1021                 $header = Linker::linkKnown( $title, $header, array(),
1022                         array( 'oldid' => $rev->getID() ) );
1023
1024                 if ( $rev->userCan( Revision::DELETED_TEXT, $user ) ) {
1025                         $editQuery = array( 'action' => 'edit' );
1026                         if ( !$rev->isCurrent() ) {
1027                                 $editQuery['oldid'] = $rev->getID();
1028                         }
1029
1030                         $key = $title->quickUserCan( 'edit', $user ) ? 'editold' : 'viewsourceold';
1031                         $msg = $this->msg( $key )->escaped();
1032                         $header .= ' ' . $this->msg( 'parentheses' )->rawParams(
1033                                 Linker::linkKnown( $title, $msg, array(), $editQuery ) )->plain();
1034                         if ( $rev->isDeleted( Revision::DELETED_TEXT ) ) {
1035                                 $header = Html::rawElement(
1036                                         'span',
1037                                         array( 'class' => 'history-deleted' ),
1038                                         $header
1039                                 );
1040                         }
1041                 } else {
1042                         $header = Html::rawElement( 'span', array( 'class' => 'history-deleted' ), $header );
1043                 }
1044
1045                 return $header;
1046         }
1047
1048         /**
1049          * Add the header to a diff body
1050          *
1051          * @param string $diff Diff body
1052          * @param string $otitle Old revision header
1053          * @param string $ntitle New revision header
1054          * @param string $multi Notice telling user that there are intermediate
1055          *   revisions between the ones being compared
1056          * @param string $notice Other notices, e.g. that user is viewing deleted content
1057          *
1058          * @return string
1059          */
1060         function addHeader( $diff, $otitle, $ntitle, $multi = '', $notice = '' ) {
1061                 // shared.css sets diff in interface language/dir, but the actual content
1062                 // is often in a different language, mostly the page content language/dir
1063                 $tableClass = 'diff diff-contentalign-' . htmlspecialchars( $this->getDiffLang()->alignStart() );
1064                 $header = "<table class='$tableClass'>";
1065
1066                 if ( !$diff && !$otitle ) {
1067                         $header .= "
1068                         <tr style='vertical-align: top;'>
1069                         <td class='diff-ntitle'>{$ntitle}</td>
1070                         </tr>";
1071                         $multiColspan = 1;
1072                 } else {
1073                         if ( $diff ) { // Safari/Chrome show broken output if cols not used
1074                                 $header .= "
1075                                 <col class='diff-marker' />
1076                                 <col class='diff-content' />
1077                                 <col class='diff-marker' />
1078                                 <col class='diff-content' />";
1079                                 $colspan = 2;
1080                                 $multiColspan = 4;
1081                         } else {
1082                                 $colspan = 1;
1083                                 $multiColspan = 2;
1084                         }
1085                         if ( $otitle || $ntitle ) {
1086                                 $header .= "
1087                                 <tr style='vertical-align: top;'>
1088                                 <td colspan='$colspan' class='diff-otitle'>{$otitle}</td>
1089                                 <td colspan='$colspan' class='diff-ntitle'>{$ntitle}</td>
1090                                 </tr>";
1091                         }
1092                 }
1093
1094                 if ( $multi != '' ) {
1095                         $header .= "<tr><td colspan='{$multiColspan}' style='text-align: center;' " .
1096                                 "class='diff-multi'>{$multi}</td></tr>";
1097                 }
1098                 if ( $notice != '' ) {
1099                         $header .= "<tr><td colspan='{$multiColspan}' style='text-align: center;'>{$notice}</td></tr>";
1100                 }
1101
1102                 return $header . $diff . "</table>";
1103         }
1104
1105         /**
1106          * Use specified text instead of loading from the database
1107          * @deprecated since 1.21, use setContent() instead.
1108          */
1109         function setText( $oldText, $newText ) {
1110                 ContentHandler::deprecated( __METHOD__, "1.21" );
1111
1112                 $oldContent = ContentHandler::makeContent( $oldText, $this->getTitle() );
1113                 $newContent = ContentHandler::makeContent( $newText, $this->getTitle() );
1114
1115                 $this->setContent( $oldContent, $newContent );
1116         }
1117
1118         /**
1119          * Use specified text instead of loading from the database
1120          * @since 1.21
1121          */
1122         function setContent( Content $oldContent, Content $newContent ) {
1123                 $this->mOldContent = $oldContent;
1124                 $this->mNewContent = $newContent;
1125
1126                 $this->mTextLoaded = 2;
1127                 $this->mRevisionsLoaded = true;
1128         }
1129
1130         /**
1131          * Set the language in which the diff text is written
1132          * (Defaults to page content language).
1133          * @since 1.19
1134          */
1135         function setTextLanguage( $lang ) {
1136                 $this->mDiffLang = wfGetLangObj( $lang );
1137         }
1138
1139         /**
1140          * Maps a revision pair definition as accepted by DifferenceEngine constructor
1141          * to a pair of actual integers representing revision ids.
1142          *
1143          * @param int $old Revision id, e.g. from URL parameter 'oldid'
1144          * @param int|string $new Revision id or strings 'next' or 'prev', e.g. from URL parameter 'diff'
1145          * @return array Array of two revision ids, older first, later second.
1146          *     Zero signifies invalid argument passed.
1147          *     false signifies that there is no previous/next revision ($old is the oldest/newest one).
1148          */
1149         public function mapDiffPrevNext( $old, $new ) {
1150                 if ( $new === 'prev' ) {
1151                         // Show diff between revision $old and the previous one. Get previous one from DB.
1152                         $newid = intval( $old );
1153                         $oldid = $this->getTitle()->getPreviousRevisionID( $newid );
1154                 } elseif ( $new === 'next' ) {
1155                         // Show diff between revision $old and the next one. Get next one from DB.
1156                         $oldid = intval( $old );
1157                         $newid = $this->getTitle()->getNextRevisionID( $oldid );
1158                 } else {
1159                         $oldid = intval( $old );
1160                         $newid = intval( $new );
1161                 }
1162
1163                 return array( $oldid, $newid );
1164         }
1165
1166         /**
1167          * Load revision IDs
1168          */
1169         private function loadRevisionIds() {
1170                 if ( $this->mRevisionsIdsLoaded ) {
1171                         return;
1172                 }
1173
1174                 $this->mRevisionsIdsLoaded = true;
1175
1176                 $old = $this->mOldid;
1177                 $new = $this->mNewid;
1178
1179                 list( $this->mOldid, $this->mNewid ) = self::mapDiffPrevNext( $old, $new );
1180                 if ( $new === 'next' && $this->mNewid === false ) {
1181                         # if no result, NewId points to the newest old revision. The only newer
1182                         # revision is cur, which is "0".
1183                         $this->mNewid = 0;
1184                 }
1185
1186                 wfRunHooks(
1187                         'NewDifferenceEngine',
1188                         array( $this->getTitle(), &$this->mOldid, &$this->mNewid, $old, $new )
1189                 );
1190         }
1191
1192         /**
1193          * Load revision metadata for the specified articles. If newid is 0, then compare
1194          * the old article in oldid to the current article; if oldid is 0, then
1195          * compare the current article to the immediately previous one (ignoring the
1196          * value of newid).
1197          *
1198          * If oldid is false, leave the corresponding revision object set
1199          * to false. This is impossible via ordinary user input, and is provided for
1200          * API convenience.
1201          *
1202          * @return bool
1203          */
1204         function loadRevisionData() {
1205                 if ( $this->mRevisionsLoaded ) {
1206                         return true;
1207                 }
1208
1209                 // Whether it succeeds or fails, we don't want to try again
1210                 $this->mRevisionsLoaded = true;
1211
1212                 $this->loadRevisionIds();
1213
1214                 // Load the new revision object
1215                 if ( $this->mNewid ) {
1216                         $this->mNewRev = Revision::newFromId( $this->mNewid );
1217                 } else {
1218                         $this->mNewRev = Revision::newFromTitle(
1219                                 $this->getTitle(),
1220                                 false,
1221                                 Revision::READ_NORMAL
1222                         );
1223                 }
1224
1225                 if ( !$this->mNewRev instanceof Revision ) {
1226                         return false;
1227                 }
1228
1229                 // Update the new revision ID in case it was 0 (makes life easier doing UI stuff)
1230                 $this->mNewid = $this->mNewRev->getId();
1231                 $this->mNewPage = $this->mNewRev->getTitle();
1232
1233                 // Load the old revision object
1234                 $this->mOldRev = false;
1235                 if ( $this->mOldid ) {
1236                         $this->mOldRev = Revision::newFromId( $this->mOldid );
1237                 } elseif ( $this->mOldid === 0 ) {
1238                         $rev = $this->mNewRev->getPrevious();
1239                         if ( $rev ) {
1240                                 $this->mOldid = $rev->getId();
1241                                 $this->mOldRev = $rev;
1242                         } else {
1243                                 // No previous revision; mark to show as first-version only.
1244                                 $this->mOldid = false;
1245                                 $this->mOldRev = false;
1246                         }
1247                 } /* elseif ( $this->mOldid === false ) leave mOldRev false; */
1248
1249                 if ( is_null( $this->mOldRev ) ) {
1250                         return false;
1251                 }
1252
1253                 if ( $this->mOldRev ) {
1254                         $this->mOldPage = $this->mOldRev->getTitle();
1255                 }
1256
1257                 // Load tags information for both revisions
1258                 $dbr = wfGetDB( DB_SLAVE );
1259                 if ( $this->mOldid !== false ) {
1260                         $this->mOldTags = $dbr->selectField(
1261                                 'tag_summary',
1262                                 'ts_tags',
1263                                 array( 'ts_rev_id' => $this->mOldid ),
1264                                 __METHOD__
1265                         );
1266                 } else {
1267                         $this->mOldTags = false;
1268                 }
1269                 $this->mNewTags = $dbr->selectField(
1270                         'tag_summary',
1271                         'ts_tags',
1272                         array( 'ts_rev_id' => $this->mNewid ),
1273                         __METHOD__
1274                 );
1275
1276                 return true;
1277         }
1278
1279         /**
1280          * Load the text of the revisions, as well as revision data.
1281          *
1282          * @return bool
1283          */
1284         function loadText() {
1285                 if ( $this->mTextLoaded == 2 ) {
1286                         return true;
1287                 }
1288
1289                 // Whether it succeeds or fails, we don't want to try again
1290                 $this->mTextLoaded = 2;
1291
1292                 if ( !$this->loadRevisionData() ) {
1293                         return false;
1294                 }
1295
1296                 if ( $this->mOldRev ) {
1297                         $this->mOldContent = $this->mOldRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1298                         if ( $this->mOldContent === null ) {
1299                                 return false;
1300                         }
1301                 }
1302
1303                 if ( $this->mNewRev ) {
1304                         $this->mNewContent = $this->mNewRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1305                         if ( $this->mNewContent === null ) {
1306                                 return false;
1307                         }
1308                 }
1309
1310                 return true;
1311         }
1312
1313         /**
1314          * Load the text of the new revision, not the old one
1315          *
1316          * @return bool
1317          */
1318         function loadNewText() {
1319                 if ( $this->mTextLoaded >= 1 ) {
1320                         return true;
1321                 }
1322
1323                 $this->mTextLoaded = 1;
1324
1325                 if ( !$this->loadRevisionData() ) {
1326                         return false;
1327                 }
1328
1329                 $this->mNewContent = $this->mNewRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1330
1331                 return true;
1332         }
1333 }