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 use MediaWiki\Storage\RevisionRecord;
  25
  26 /**
  27  * DifferenceEngine is responsible for rendering the difference between two revisions as HTML.
  28  * This includes interpreting URL parameters, retrieving revision data, checking access permissions,
  29  * selecting and invoking the diff generator class for the individual slots, doing post-processing
  30  * on the generated diff, adding the rest of the HTML (such as headers) and writing the whole thing
  31  * to OutputPage.
  32  *
  33  * DifferenceEngine can be subclassed by extensions, by customizing
  34  * ContentHandler::createDifferenceEngine; the content handler will be selected based on the
  35  * content model of the main slot (of the new revision, when the two are different).
  36  * That might change after PageTypeHandler gets introduced.
  37  *
  38  * In the past, the class was also used for slot-level diff generation, and extensions might still
  39  * subclass it and add such functionality. When that is the case (sepcifically, when a
  40  * ContentHandler returns a standard SlotDiffRenderer but a nonstandard DifferenceEngine)
  41  * DifferenceEngineSlotDiffRenderer will be used to convert the old behavior into the new one.
  42  *
  43  * @ingroup DifferenceEngine
  44  *
  45  * @todo This class is huge and poorly defined. It should be split into a controller responsible
  46  * for interpreting query parameters, retrieving data and checking permissions; and a HTML renderer.
  47  */
  48 class DifferenceEngine extends ContextSource {
  49
  50         use DeprecationHelper;
  51
  52         /**
  53          * Constant to indicate diff cache compatibility.
  54          * Bump this when changing the diff formatting in a way that
  55          * fixes important bugs or such to force cached diff views to
  56          * clear.
  57          */
  58         const DIFF_VERSION = '1.12';
  59
  60         /** @var int Revision ID or 0 for current */
  61         protected $mOldid;
  62
  63         /** @var int|string Revision ID or null for current or an alias such as 'next' */
  64         protected $mNewid;
  65
  66         private $mOldTags;
  67         private $mNewTags;
  68
  69         /**
  70          * Old revision (left pane).
  71          * Allowed to be an unsaved revision, unlikely that's ever needed though.
  72          * Null when the old revision does not exist; this can happen when using
  73          * diff=prev on the first revision.
  74          * Since 1.32 public access is deprecated.
  75          * @var Revision|null
  76          */
  77         protected $mOldRev;
  78
  79         /**
  80          * New revision (right pane).
  81          * Note that this might be an unsaved revision (e.g. for edit preview).
  82          * Null only in case of load failure; diff methods will just return an error message in that case.
  83          * Since 1.32 public access is deprecated.
  84          * @var Revision|null
  85          */
  86         protected $mNewRev;
  87
  88         /**
  89          * Title of $mOldRev or null if the old revision does not exist or does not belong to a page.
  90          * Since 1.32 public access is deprecated and the property can be null.
  91          * @var Title|null
  92          */
  93         protected $mOldPage;
  94
  95         /**
  96          * Title of $mNewRev or null if the new revision does not exist or does not belong to a page.
  97          * Since 1.32 public access is deprecated and the property can be null.
  98          * @var Title|null
  99          */
 100         protected $mNewPage;
 101
 102         /**
 103          * @var Content|null
 104          * @deprecated since 1.32, content slots are now handled by the corresponding SlotDiffRenderer.
 105          *   This property is set to the content of the main slot, but not actually used for the main diff.
 106          */
 107         private $mOldContent;
 108
 109         /**
 110          * @var Content|null
 111          * @deprecated since 1.32, content slots are now handled by the corresponding SlotDiffRenderer.
 112          *   This property is set to the content of the main slot, but not actually used for the main diff.
 113          */
 114         private $mNewContent;
 115
 116         /** @var Language */
 117         protected $mDiffLang;
 118
 119         /** @var bool Have the revisions IDs been loaded */
 120         private $mRevisionsIdsLoaded = false;
 121
 122         /** @var bool Have the revisions been loaded */
 123         protected $mRevisionsLoaded = false;
 124
 125         /** @var int How many text blobs have been loaded, 0, 1 or 2? */
 126         protected $mTextLoaded = 0;
 127
 128         /**
 129          * Was the content overridden via setContent()?
 130          * If the content was overridden, most internal state (e.g. mOldid or mOldRev) should be ignored
 131          * and only mOldContent and mNewContent is reliable.
 132          * (Note that setRevisions() does not set this flag as in that case all properties are
 133          * overriden and remain consistent with each other, so no special handling is needed.)
 134          * @var bool
 135          */
 136         protected $isContentOverridden = false;
 137
 138         /** @var bool Was the diff fetched from cache? */
 139         protected $mCacheHit = false;
 140
 141         /**
 142          * Set this to true to add debug info to the HTML output.
 143          * Warning: this may cause RSS readers to spuriously mark articles as "new"
 144          * (T22601)
 145          */
 146         public $enableDebugComment = false;
 147
 148         /** @var bool If true, line X is not displayed when X is 1, for example
 149          *    to increase readability and conserve space with many small diffs.
 150          */
 151         protected $mReducedLineNumbers = false;
 152
 153         /** @var string Link to action=markpatrolled */
 154         protected $mMarkPatrolledLink = null;
 155
 156         /** @var bool Show rev_deleted content if allowed */
 157         protected $unhide = false;
 158
 159         /** @var bool Refresh the diff cache */
 160         protected $mRefreshCache = false;
 161
 162         /** @var SlotDiffRenderer[] DifferenceEngine classes for the slots, keyed by role name. */
 163         protected $slotDiffRenderers = null;
 164
 165         /**
 166          * Temporary hack for B/C while slot diff related methods of DifferenceEngine are being
 167          * deprecated. When true, we are inside a DifferenceEngineSlotDiffRenderer and
 168          * $slotDiffRenderers should not be used.
 169          * @var bool
 170          */
 171         protected $isSlotDiffRenderer = false;
 172
 173         /**#@-*/
 174
 175         /**
 176          * @param IContextSource|null $context Context to use, anything else will be ignored
 177          * @param int $old Old ID we want to show and diff with.
 178          * @param string|int $new Either revision ID or 'prev' or 'next'. Default: 0.
 179          * @param int $rcid Deprecated, no longer used!
 180          * @param bool $refreshCache If set, refreshes the diff cache
 181          * @param bool $unhide If set, allow viewing deleted revs
 182          */
 183         public function __construct( $context = null, $old = 0, $new = 0, $rcid = 0,
 184                 $refreshCache = false, $unhide = false
 185         ) {
 186                 $this->deprecatePublicProperty( 'mOldid', '1.32', __CLASS__ );
 187                 $this->deprecatePublicProperty( 'mNewid', '1.32', __CLASS__ );
 188                 $this->deprecatePublicProperty( 'mOldRev', '1.32', __CLASS__ );
 189                 $this->deprecatePublicProperty( 'mNewRev', '1.32', __CLASS__ );
 190                 $this->deprecatePublicProperty( 'mOldPage', '1.32', __CLASS__ );
 191                 $this->deprecatePublicProperty( 'mNewPage', '1.32', __CLASS__ );
 192                 $this->deprecatePublicProperty( 'mOldContent', '1.32', __CLASS__ );
 193                 $this->deprecatePublicProperty( 'mNewContent', '1.32', __CLASS__ );
 194                 $this->deprecatePublicProperty( 'mRevisionsLoaded', '1.32', __CLASS__ );
 195                 $this->deprecatePublicProperty( 'mTextLoaded', '1.32', __CLASS__ );
 196                 $this->deprecatePublicProperty( 'mCacheHit', '1.32', __CLASS__ );
 197
 198                 if ( $context instanceof IContextSource ) {
 199                         $this->setContext( $context );
 200                 }
 201
 202                 wfDebug( "DifferenceEngine old '$old' new '$new' rcid '$rcid'\n" );
 203
 204                 $this->mOldid = $old;
 205                 $this->mNewid = $new;
 206                 $this->mRefreshCache = $refreshCache;
 207                 $this->unhide = $unhide;
 208         }
 209
 210         /**
 211          * @return SlotDiffRenderer[] Diff renderers for each slot, keyed by role name.
 212          *   Includes slots only present in one of the revisions.
 213          */
 214         protected function getSlotDiffRenderers() {
 215                 if ( $this->isSlotDiffRenderer ) {
 216                         throw new LogicException( __METHOD__ . ' called in slot diff renderer mode' );
 217                 }
 218
 219                 if ( $this->slotDiffRenderers === null ) {
 220                         if ( !$this->loadRevisionData() ) {
 221                                 return [];
 222                         }
 223
 224                         $slotContents = $this->getSlotContents();
 225                         $this->slotDiffRenderers = array_map( function ( $contents ) {
 226                                 /** @var $content Content */
 227                                 $content = $contents['new'] ?: $contents['old'];
 228                                 return $content->getContentHandler()->getSlotDiffRenderer( $this->getContext() );
 229                         }, $slotContents );
 230                 }
 231                 return $this->slotDiffRenderers;
 232         }
 233
 234         /**
 235          * Mark this DifferenceEngine as a slot renderer (as opposed to a page renderer).
 236          * This is used in legacy mode when the DifferenceEngine is wrapped in a
 237          * DifferenceEngineSlotDiffRenderer.
 238          * @internal For use by DifferenceEngineSlotDiffRenderer only.
 239          */
 240         public function markAsSlotDiffRenderer() {
 241                 $this->isSlotDiffRenderer = true;
 242         }
 243
 244         /**
 245          * Get the old and new content objects for all slots.
 246          * This method does not do any permission checks.
 247          * @return array [ role => [ 'old' => SlotRecord, 'new' => SlotRecord ], ... ]
 248          */
 249         protected function getSlotContents() {
 250                 if ( $this->isContentOverridden ) {
 251                         return [
 252                                 'main' => [
 253                                         'old' => $this->mOldContent,
 254                                         'new' => $this->mNewContent,
 255                                 ]
 256                         ];
 257                 }
 258
 259                 $oldRev = $this->mOldRev->getRevisionRecord();
 260                 $newRev = $this->mNewRev->getRevisionRecord();
 261                 // The order here will determine the visual order of the diff. The current logic is
 262                 // changed first, then added, then deleted. This is ad hoc and should not be relied on
 263                 // - in the future we may want the ordering to depend on the page type.
 264                 $roles = array_merge( $newRev->getSlotRoles(), $oldRev->getSlotRoles() );
 265                 $oldSlots = $oldRev->getSlots()->getSlots();
 266                 $newSlots = $newRev->getSlots()->getSlots();
 267
 268                 $slots = [];
 269                 foreach ( $roles as $role ) {
 270                         $slots[$role] = [
 271                                 'old' => isset( $oldSlots[$role] ) ? $oldSlots[$role]->getContent() : null,
 272                                 'new' => isset( $newSlots[$role] ) ? $newSlots[$role]->getContent() : null,
 273                         ];
 274                 }
 275                 // move main slot to front
 276                 if ( isset( $slots['main'] ) ) {
 277                         $slots = [ 'main' => $slots['main'] ] + $slots;
 278                 }
 279                 return $slots;
 280         }
 281
 282         public function getTitle() {
 283                 // T202454 avoid errors when there is no title
 284                 return parent::getTitle() ?: Title::makeTitle( NS_SPECIAL, 'BadTitle/DifferenceEngine' );
 285         }
 286
 287         /**
 288          * Set reduced line numbers mode.
 289          * When set, line X is not displayed when X is 1, for example to increase readability and
 290          * conserve space with many small diffs.
 291          * @param bool $value
 292          */
 293         public function setReducedLineNumbers( $value = true ) {
 294                 $this->mReducedLineNumbers = $value;
 295         }
 296
 297         /**
 298          * Get the language of the difference engine, defaults to page content language
 299          *
 300          * @return Language
 301          */
 302         public function getDiffLang() {
 303                 if ( $this->mDiffLang === null ) {
 304                         # Default language in which the diff text is written.
 305                         $this->mDiffLang = $this->getTitle()->getPageLanguage();
 306                 }
 307
 308                 return $this->mDiffLang;
 309         }
 310
 311         /**
 312          * @return bool
 313          */
 314         public function wasCacheHit() {
 315                 return $this->mCacheHit;
 316         }
 317
 318         /**
 319          * @return int
 320          */
 321         public function getOldid() {
 322                 $this->loadRevisionIds();
 323
 324                 return $this->mOldid;
 325         }
 326
 327         /**
 328          * @return bool|int
 329          */
 330         public function getNewid() {
 331                 $this->loadRevisionIds();
 332
 333                 return $this->mNewid;
 334         }
 335
 336         /**
 337          * Get the left side of the diff.
 338          * Could be null when the first revision of the page is diffed to 'prev' (or in the case of
 339          * load failure).
 340          * @return RevisionRecord|null
 341          */
 342         public function getOldRevision() {
 343                 return $this->mOldRev ? $this->mOldRev->getRevisionRecord() : null;
 344         }
 345
 346         /**
 347          * Get the right side of the diff.
 348          * Should not be null but can still happen in the case of load failure.
 349          * @return RevisionRecord|null
 350          */
 351         public function getNewRevision() {
 352                 return $this->mNewRev ? $this->mNewRev->getRevisionRecord() : null;
 353         }
 354
 355         /**
 356          * Look up a special:Undelete link to the given deleted revision id,
 357          * as a workaround for being unable to load deleted diffs in currently.
 358          *
 359          * @param int $id Revision ID
 360          *
 361          * @return string|bool Link HTML or false
 362          */
 363         public function deletedLink( $id ) {
 364                 if ( $this->getUser()->isAllowed( 'deletedhistory' ) ) {
 365                         $dbr = wfGetDB( DB_REPLICA );
 366                         $arQuery = Revision::getArchiveQueryInfo();
 367                         $row = $dbr->selectRow(
 368                                 $arQuery['tables'],
 369                                 array_merge( $arQuery['fields'], [ 'ar_namespace', 'ar_title' ] ),
 370                                 [ 'ar_rev_id' => $id ],
 371                                 __METHOD__,
 372                                 [],
 373                                 $arQuery['joins']
 374                         );
 375                         if ( $row ) {
 376                                 $rev = Revision::newFromArchiveRow( $row );
 377                                 $title = Title::makeTitleSafe( $row->ar_namespace, $row->ar_title );
 378
 379                                 return SpecialPage::getTitleFor( 'Undelete' )->getFullURL( [
 380                                         'target' => $title->getPrefixedText(),
 381                                         'timestamp' => $rev->getTimestamp()
 382                                 ] );
 383                         }
 384                 }
 385
 386                 return false;
 387         }
 388
 389         /**
 390          * Build a wikitext link toward a deleted revision, if viewable.
 391          *
 392          * @param int $id Revision ID
 393          *
 394          * @return string Wikitext fragment
 395          */
 396         public function deletedIdMarker( $id ) {
 397                 $link = $this->deletedLink( $id );
 398                 if ( $link ) {
 399                         return "[$link $id]";
 400                 } else {
 401                         return (string)$id;
 402                 }
 403         }
 404
 405         private function showMissingRevision() {
 406                 $out = $this->getOutput();
 407
 408                 $missing = [];
 409                 if ( $this->mOldRev === null ||
 410                         ( $this->mOldRev && $this->mOldContent === null )
 411                 ) {
 412                         $missing[] = $this->deletedIdMarker( $this->mOldid );
 413                 }
 414                 if ( $this->mNewRev === null ||
 415                         ( $this->mNewRev && $this->mNewContent === null )
 416                 ) {
 417                         $missing[] = $this->deletedIdMarker( $this->mNewid );
 418                 }
 419
 420                 $out->setPageTitle( $this->msg( 'errorpagetitle' ) );
 421                 $msg = $this->msg( 'difference-missing-revision' )
 422                         ->params( $this->getLanguage()->listToText( $missing ) )
 423                         ->numParams( count( $missing ) )
 424                         ->parseAsBlock();
 425                 $out->addHTML( $msg );
 426         }
 427
 428         public function showDiffPage( $diffOnly = false ) {
 429                 # Allow frames except in certain special cases
 430                 $out = $this->getOutput();
 431                 $out->allowClickjacking();
 432                 $out->setRobotPolicy( 'noindex,nofollow' );
 433
 434                 // Allow extensions to add any extra output here
 435                 Hooks::run( 'DifferenceEngineShowDiffPage', [ $out ] );
 436
 437                 if ( !$this->loadRevisionData() ) {
 438                         if ( Hooks::run( 'DifferenceEngineShowDiffPageMaybeShowMissingRevision', [ $this ] ) ) {
 439                                 $this->showMissingRevision();
 440                         }
 441                         return;
 442                 }
 443
 444                 $user = $this->getUser();
 445                 $permErrors = [];
 446                 if ( $this->mNewPage ) {
 447                         $permErrors = $this->mNewPage->getUserPermissionsErrors( 'read', $user );
 448                 }
 449                 if ( $this->mOldPage ) {
 450                         $permErrors = wfMergeErrorArrays( $permErrors,
 451                                 $this->mOldPage->getUserPermissionsErrors( 'read', $user ) );
 452                 }
 453                 if ( count( $permErrors ) ) {
 454                         throw new PermissionsError( 'read', $permErrors );
 455                 }
 456
 457                 $rollback = '';
 458
 459                 $query = [];
 460                 # Carry over 'diffonly' param via navigation links
 461                 if ( $diffOnly != $user->getBoolOption( 'diffonly' ) ) {
 462                         $query['diffonly'] = $diffOnly;
 463                 }
 464                 # Cascade unhide param in links for easy deletion browsing
 465                 if ( $this->unhide ) {
 466                         $query['unhide'] = 1;
 467                 }
 468
 469                 # Check if one of the revisions is deleted/suppressed
 470                 $deleted = $suppressed = false;
 471                 $allowed = $this->mNewRev->userCan( Revision::DELETED_TEXT, $user );
 472
 473                 $revisionTools = [];
 474
 475                 # mOldRev is false if the difference engine is called with a "vague" query for
 476                 # a diff between a version V and its previous version V' AND the version V
 477                 # is the first version of that article. In that case, V' does not exist.
 478                 if ( $this->mOldRev === false ) {
 479                         if ( $this->mNewPage ) {
 480                                 $out->setPageTitle( $this->msg( 'difference-title', $this->mNewPage->getPrefixedText() ) );
 481                         }
 482                         $samePage = true;
 483                         $oldHeader = '';
 484                         // Allow extensions to change the $oldHeader variable
 485                         Hooks::run( 'DifferenceEngineOldHeaderNoOldRev', [ &$oldHeader ] );
 486                 } else {
 487                         Hooks::run( 'DiffViewHeader', [ $this, $this->mOldRev, $this->mNewRev ] );
 488
 489                         if ( !$this->mOldPage || !$this->mNewPage ) {
 490                                 // XXX say something to the user?
 491                                 $samePage = false;
 492                         } elseif ( $this->mNewPage->equals( $this->mOldPage ) ) {
 493                                 $out->setPageTitle( $this->msg( 'difference-title', $this->mNewPage->getPrefixedText() ) );
 494                                 $samePage = true;
 495                         } else {
 496                                 $out->setPageTitle( $this->msg( 'difference-title-multipage',
 497                                         $this->mOldPage->getPrefixedText(), $this->mNewPage->getPrefixedText() ) );
 498                                 $out->addSubtitle( $this->msg( 'difference-multipage' ) );
 499                                 $samePage = false;
 500                         }
 501
 502                         if ( $samePage && $this->mNewPage && $this->mNewPage->quickUserCan( 'edit', $user ) ) {
 503                                 if ( $this->mNewRev->isCurrent() && $this->mNewPage->userCan( 'rollback', $user ) ) {
 504                                         $rollbackLink = Linker::generateRollback( $this->mNewRev, $this->getContext() );
 505                                         if ( $rollbackLink ) {
 506                                                 $out->preventClickjacking();
 507                                                 $rollback = "\u{00A0}\u{00A0}\u{00A0}" . $rollbackLink;
 508                                         }
 509                                 }
 510
 511                                 if ( !$this->mOldRev->isDeleted( Revision::DELETED_TEXT ) &&
 512                                         !$this->mNewRev->isDeleted( Revision::DELETED_TEXT )
 513                                 ) {
 514                                         $undoLink = Html::element( 'a', [
 515                                                         'href' => $this->mNewPage->getLocalURL( [
 516                                                                 'action' => 'edit',
 517                                                                 'undoafter' => $this->mOldid,
 518                                                                 'undo' => $this->mNewid
 519                                                         ] ),
 520                                                         'title' => Linker::titleAttrib( 'undo' ),
 521                                                 ],
 522                                                 $this->msg( 'editundo' )->text()
 523                                         );
 524                                         $revisionTools['mw-diff-undo'] = $undoLink;
 525                                 }
 526                         }
 527
 528                         # Make "previous revision link"
 529                         if ( $samePage && $this->mOldPage && $this->mOldRev->getPrevious() ) {
 530                                 $prevlink = Linker::linkKnown(
 531                                         $this->mOldPage,
 532                                         $this->msg( 'previousdiff' )->escaped(),
 533                                         [ 'id' => 'differences-prevlink' ],
 534                                         [ 'diff' => 'prev', 'oldid' => $this->mOldid ] + $query
 535                                 );
 536                         } else {
 537                                 $prevlink = "\u{00A0}";
 538                         }
 539
 540                         if ( $this->mOldRev->isMinor() ) {
 541                                 $oldminor = ChangesList::flag( 'minor' );
 542                         } else {
 543                                 $oldminor = '';
 544                         }
 545
 546                         $ldel = $this->revisionDeleteLink( $this->mOldRev );
 547                         $oldRevisionHeader = $this->getRevisionHeader( $this->mOldRev, 'complete' );
 548                         $oldChangeTags = ChangeTags::formatSummaryRow( $this->mOldTags, 'diff', $this->getContext() );
 549
 550                         $oldHeader = '<div id="mw-diff-otitle1"><strong>' . $oldRevisionHeader . '</strong></div>' .
 551                                 '<div id="mw-diff-otitle2">' .
 552                                 Linker::revUserTools( $this->mOldRev, !$this->unhide ) . '</div>' .
 553                                 '<div id="mw-diff-otitle3">' . $oldminor .
 554                                 Linker::revComment( $this->mOldRev, !$diffOnly, !$this->unhide ) . $ldel . '</div>' .
 555                                 '<div id="mw-diff-otitle5">' . $oldChangeTags[0] . '</div>' .
 556                                 '<div id="mw-diff-otitle4">' . $prevlink . '</div>';
 557
 558                         // Allow extensions to change the $oldHeader variable
 559                         Hooks::run( 'DifferenceEngineOldHeader', [ $this, &$oldHeader, $prevlink, $oldminor,
 560                                 $diffOnly, $ldel, $this->unhide ] );
 561
 562                         if ( $this->mOldRev->isDeleted( Revision::DELETED_TEXT ) ) {
 563                                 $deleted = true; // old revisions text is hidden
 564                                 if ( $this->mOldRev->isDeleted( Revision::DELETED_RESTRICTED ) ) {
 565                                         $suppressed = true; // also suppressed
 566                                 }
 567                         }
 568
 569                         # Check if this user can see the revisions
 570                         if ( !$this->mOldRev->userCan( Revision::DELETED_TEXT, $user ) ) {
 571                                 $allowed = false;
 572                         }
 573                 }
 574
 575                 $out->addJsConfigVars( [
 576                         'wgDiffOldId' => $this->mOldid,
 577                         'wgDiffNewId' => $this->mNewid,
 578                 ] );
 579
 580                 # Make "next revision link"
 581                 # Skip next link on the top revision
 582                 if ( $samePage && $this->mNewPage && !$this->mNewRev->isCurrent() ) {
 583                         $nextlink = Linker::linkKnown(
 584                                 $this->mNewPage,
 585                                 $this->msg( 'nextdiff' )->escaped(),
 586                                 [ 'id' => 'differences-nextlink' ],
 587                                 [ 'diff' => 'next', 'oldid' => $this->mNewid ] + $query
 588                         );
 589                 } else {
 590                         $nextlink = "\u{00A0}";
 591                 }
 592
 593                 if ( $this->mNewRev->isMinor() ) {
 594                         $newminor = ChangesList::flag( 'minor' );
 595                 } else {
 596                         $newminor = '';
 597                 }
 598
 599                 # Handle RevisionDelete links...
 600                 $rdel = $this->revisionDeleteLink( $this->mNewRev );
 601
 602                 # Allow extensions to define their own revision tools
 603                 Hooks::run( 'DiffRevisionTools',
 604                         [ $this->mNewRev, &$revisionTools, $this->mOldRev, $user ] );
 605                 $formattedRevisionTools = [];
 606                 // Put each one in parentheses (poor man's button)
 607                 foreach ( $revisionTools as $key => $tool ) {
 608                         $toolClass = is_string( $key ) ? $key : 'mw-diff-tool';
 609                         $element = Html::rawElement(
 610                                 'span',
 611                                 [ 'class' => $toolClass ],
 612                                 $this->msg( 'parentheses' )->rawParams( $tool )->escaped()
 613                         );
 614                         $formattedRevisionTools[] = $element;
 615                 }
 616                 $newRevisionHeader = $this->getRevisionHeader( $this->mNewRev, 'complete' ) .
 617                         ' ' . implode( ' ', $formattedRevisionTools );
 618                 $newChangeTags = ChangeTags::formatSummaryRow( $this->mNewTags, 'diff', $this->getContext() );
 619
 620                 $newHeader = '<div id="mw-diff-ntitle1"><strong>' . $newRevisionHeader . '</strong></div>' .
 621                         '<div id="mw-diff-ntitle2">' . Linker::revUserTools( $this->mNewRev, !$this->unhide ) .
 622                         " $rollback</div>" .
 623                         '<div id="mw-diff-ntitle3">' . $newminor .
 624                         Linker::revComment( $this->mNewRev, !$diffOnly, !$this->unhide ) . $rdel . '</div>' .
 625                         '<div id="mw-diff-ntitle5">' . $newChangeTags[0] . '</div>' .
 626                         '<div id="mw-diff-ntitle4">' . $nextlink . $this->markPatrolledLink() . '</div>';
 627
 628                 // Allow extensions to change the $newHeader variable
 629                 Hooks::run( 'DifferenceEngineNewHeader', [ $this, &$newHeader, $formattedRevisionTools,
 630                         $nextlink, $rollback, $newminor, $diffOnly, $rdel, $this->unhide ] );
 631
 632                 if ( $this->mNewRev->isDeleted( Revision::DELETED_TEXT ) ) {
 633                         $deleted = true; // new revisions text is hidden
 634                         if ( $this->mNewRev->isDeleted( Revision::DELETED_RESTRICTED ) ) {
 635                                 $suppressed = true; // also suppressed
 636                         }
 637                 }
 638
 639                 # If the diff cannot be shown due to a deleted revision, then output
 640                 # the diff header and links to unhide (if available)...
 641                 if ( $deleted && ( !$this->unhide || !$allowed ) ) {
 642                         $this->showDiffStyle();
 643                         $multi = $this->getMultiNotice();
 644                         $out->addHTML( $this->addHeader( '', $oldHeader, $newHeader, $multi ) );
 645                         if ( !$allowed ) {
 646                                 $msg = $suppressed ? 'rev-suppressed-no-diff' : 'rev-deleted-no-diff';
 647                                 # Give explanation for why revision is not visible
 648                                 $out->wrapWikiMsg( "<div id='mw-$msg' class='mw-warning plainlinks'>\n$1\n</div>\n",
 649                                         [ $msg ] );
 650                         } else {
 651                                 # Give explanation and add a link to view the diff...
 652                                 $query = $this->getRequest()->appendQueryValue( 'unhide', '1' );
 653                                 $link = $this->getTitle()->getFullURL( $query );
 654                                 $msg = $suppressed ? 'rev-suppressed-unhide-diff' : 'rev-deleted-unhide-diff';
 655                                 $out->wrapWikiMsg(
 656                                         "<div id='mw-$msg' class='mw-warning plainlinks'>\n$1\n</div>\n",
 657                                         [ $msg, $link ]
 658                                 );
 659                         }
 660                 # Otherwise, output a regular diff...
 661                 } else {
 662                         # Add deletion notice if the user is viewing deleted content
 663                         $notice = '';
 664                         if ( $deleted ) {
 665                                 $msg = $suppressed ? 'rev-suppressed-diff-view' : 'rev-deleted-diff-view';
 666                                 $notice = "<div id='mw-$msg' class='mw-warning plainlinks'>\n" .
 667                                         $this->msg( $msg )->parse() .
 668                                         "</div>\n";
 669                         }
 670                         $this->showDiff( $oldHeader, $newHeader, $notice );
 671                         if ( !$diffOnly ) {
 672                                 $this->renderNewRevision();
 673                         }
 674                 }
 675         }
 676
 677         /**
 678          * Build a link to mark a change as patrolled.
 679          *
 680          * Returns empty string if there's either no revision to patrol or the user is not allowed to.
 681          * Side effect: When the patrol link is build, this method will call
 682          * OutputPage::preventClickjacking() and load mediawiki.page.patrol.ajax.
 683          *
 684          * @return string HTML or empty string
 685          */
 686         public function markPatrolledLink() {
 687                 if ( $this->mMarkPatrolledLink === null ) {
 688                         $linkInfo = $this->getMarkPatrolledLinkInfo();
 689                         // If false, there is no patrol link needed/allowed
 690                         if ( !$linkInfo || !$this->mNewPage ) {
 691                                 $this->mMarkPatrolledLink = '';
 692                         } else {
 693                                 $this->mMarkPatrolledLink = ' <span class="patrollink" data-mw="interface">[' .
 694                                         Linker::linkKnown(
 695                                                 $this->mNewPage,
 696                                                 $this->msg( 'markaspatrolleddiff' )->escaped(),
 697                                                 [],
 698                                                 [
 699                                                         'action' => 'markpatrolled',
 700                                                         'rcid' => $linkInfo['rcid'],
 701                                                 ]
 702                                         ) . ']</span>';
 703                                 // Allow extensions to change the markpatrolled link
 704                                 Hooks::run( 'DifferenceEngineMarkPatrolledLink', [ $this,
 705                                         &$this->mMarkPatrolledLink, $linkInfo['rcid'] ] );
 706                         }
 707                 }
 708                 return $this->mMarkPatrolledLink;
 709         }
 710
 711         /**
 712          * Returns an array of meta data needed to build a "mark as patrolled" link and
 713          * adds the mediawiki.page.patrol.ajax to the output.
 714          *
 715          * @return array|false An array of meta data for a patrol link (rcid only)
 716          *  or false if no link is needed
 717          */
 718         protected function getMarkPatrolledLinkInfo() {
 719                 global $wgUseRCPatrol;
 720
 721                 $user = $this->getUser();
 722
 723                 // Prepare a change patrol link, if applicable
 724                 if (
 725                         // Is patrolling enabled and the user allowed to?
 726                         $wgUseRCPatrol && $this->mNewPage && $this->mNewPage->quickUserCan( 'patrol', $user ) &&
 727                         // Only do this if the revision isn't more than 6 hours older
 728                         // than the Max RC age (6h because the RC might not be cleaned out regularly)
 729                         RecentChange::isInRCLifespan( $this->mNewRev->getTimestamp(), 21600 )
 730                 ) {
 731                         // Look for an unpatrolled change corresponding to this diff
 732                         $db = wfGetDB( DB_REPLICA );
 733                         $change = RecentChange::newFromConds(
 734                                 [
 735                                         'rc_timestamp' => $db->timestamp( $this->mNewRev->getTimestamp() ),
 736                                         'rc_this_oldid' => $this->mNewid,
 737                                         'rc_patrolled' => RecentChange::PRC_UNPATROLLED
 738                                 ],
 739                                 __METHOD__
 740                         );
 741
 742                         if ( $change && !$change->getPerformer()->equals( $user ) ) {
 743                                 $rcid = $change->getAttribute( 'rc_id' );
 744                         } else {
 745                                 // None found or the page has been created by the current user.
 746                                 // If the user could patrol this it already would be patrolled
 747                                 $rcid = 0;
 748                         }
 749
 750                         // Allow extensions to possibly change the rcid here
 751                         // For example the rcid might be set to zero due to the user
 752                         // being the same as the performer of the change but an extension
 753                         // might still want to show it under certain conditions
 754                         Hooks::run( 'DifferenceEngineMarkPatrolledRCID', [ &$rcid, $this, $change, $user ] );
 755
 756                         // Build the link
 757                         if ( $rcid ) {
 758                                 $this->getOutput()->preventClickjacking();
 759                                 if ( $user->isAllowed( 'writeapi' ) ) {
 760                                         $this->getOutput()->addModules( 'mediawiki.page.patrol.ajax' );
 761                                 }
 762
 763                                 return [
 764                                         'rcid' => $rcid,
 765                                 ];
 766                         }
 767                 }
 768
 769                 // No mark as patrolled link applicable
 770                 return false;
 771         }
 772
 773         /**
 774          * @param Revision $rev
 775          *
 776          * @return string
 777          */
 778         protected function revisionDeleteLink( $rev ) {
 779                 $link = Linker::getRevDeleteLink( $this->getUser(), $rev, $rev->getTitle() );
 780                 if ( $link !== '' ) {
 781                         $link = "\u{00A0}\u{00A0}\u{00A0}" . $link . ' ';
 782                 }
 783
 784                 return $link;
 785         }
 786
 787         /**
 788          * Show the new revision of the page.
 789          */
 790         public function renderNewRevision() {
 791                 $out = $this->getOutput();
 792                 $revHeader = $this->getRevisionHeader( $this->mNewRev );
 793                 # Add "current version as of X" title
 794                 $out->addHTML( "<hr class='diff-hr' id='mw-oldid' />
 795                 <h2 class='diff-currentversion-title'>{$revHeader}</h2>\n" );
 796                 # Page content may be handled by a hooked call instead...
 797                 if ( Hooks::run( 'ArticleContentOnDiff', [ $this, $out ] ) ) {
 798                         $this->loadNewText();
 799                         if ( !$this->mNewPage ) {
 800                                 // New revision is unsaved; bail out.
 801                                 // TODO in theory rendering the new revision is a meaningful thing to do
 802                                 // even if it's unsaved, but a lot of untangling is required to do it safely.
 803                         }
 804
 805                         $out->setRevisionId( $this->mNewid );
 806                         $out->setRevisionTimestamp( $this->mNewRev->getTimestamp() );
 807                         $out->setArticleFlag( true );
 808
 809                         if ( !Hooks::run( 'ArticleContentViewCustom',
 810                                 [ $this->mNewContent, $this->mNewPage, $out ] )
 811                         ) {
 812                                 // Handled by extension
 813                         } else {
 814                                 // Normal page
 815                                 if ( $this->getTitle()->equals( $this->mNewPage ) ) {
 816                                         // If the Title stored in the context is the same as the one
 817                                         // of the new revision, we can use its associated WikiPage
 818                                         // object.
 819                                         $wikiPage = $this->getWikiPage();
 820                                 } else {
 821                                         // Otherwise we need to create our own WikiPage object
 822                                         $wikiPage = WikiPage::factory( $this->mNewPage );
 823                                 }
 824
 825                                 $parserOutput = $this->getParserOutput( $wikiPage, $this->mNewRev );
 826
 827                                 # WikiPage::getParserOutput() should not return false, but just in case
 828                                 if ( $parserOutput ) {
 829                                         // Allow extensions to change parser output here
 830                                         if ( Hooks::run( 'DifferenceEngineRenderRevisionAddParserOutput',
 831                                                 [ $this, $out, $parserOutput, $wikiPage ] )
 832                                         ) {
 833                                                 $out->addParserOutput( $parserOutput, [
 834                                                         'enableSectionEditLinks' => $this->mNewRev->isCurrent()
 835                                                                 && $this->mNewRev->getTitle()->quickUserCan( 'edit', $this->getUser() ),
 836                                                 ] );
 837                                         }
 838                                 }
 839                         }
 840                 }
 841
 842                 // Allow extensions to optionally not show the final patrolled link
 843                 if ( Hooks::run( 'DifferenceEngineRenderRevisionShowFinalPatrolLink' ) ) {
 844                         # Add redundant patrol link on bottom...
 845                         $out->addHTML( $this->markPatrolledLink() );
 846                 }
 847         }
 848
 849         /**
 850          * @param WikiPage $page
 851          * @param Revision $rev
 852          *
 853          * @return ParserOutput|bool False if the revision was not found
 854          */
 855         protected function getParserOutput( WikiPage $page, Revision $rev ) {
 856                 $parserOptions = $page->makeParserOptions( $this->getContext() );
 857                 $parserOutput = $page->getParserOutput( $parserOptions, $rev->getId() );
 858
 859                 return $parserOutput;
 860         }
 861
 862         /**
 863          * Get the diff text, send it to the OutputPage object
 864          * Returns false if the diff could not be generated, otherwise returns true
 865          *
 866          * @param string|bool $otitle Header for old text or false
 867          * @param string|bool $ntitle Header for new text or false
 868          * @param string $notice HTML between diff header and body
 869          *
 870          * @return bool
 871          */
 872         public function showDiff( $otitle, $ntitle, $notice = '' ) {
 873                 // Allow extensions to affect the output here
 874                 Hooks::run( 'DifferenceEngineShowDiff', [ $this ] );
 875
 876                 $diff = $this->getDiff( $otitle, $ntitle, $notice );
 877                 if ( $diff === false ) {
 878                         $this->showMissingRevision();
 879
 880                         return false;
 881                 } else {
 882                         $this->showDiffStyle();
 883                         $this->getOutput()->addHTML( $diff );
 884
 885                         return true;
 886                 }
 887         }
 888
 889         /**
 890          * Add style sheets for diff display.
 891          */
 892         public function showDiffStyle() {
 893                 if ( !$this->isSlotDiffRenderer ) {
 894                         $this->getOutput()->addModuleStyles( 'mediawiki.diff.styles' );
 895                         foreach ( $this->getSlotDiffRenderers() as $slotDiffRenderer ) {
 896                                 $slotDiffRenderer->addModules( $this->getOutput() );
 897                         }
 898                 }
 899         }
 900
 901         /**
 902          * Get complete diff table, including header
 903          *
 904          * @param string|bool $otitle Header for old text or false
 905          * @param string|bool $ntitle Header for new text or false
 906          * @param string $notice HTML between diff header and body
 907          *
 908          * @return mixed
 909          */
 910         public function getDiff( $otitle, $ntitle, $notice = '' ) {
 911                 $body = $this->getDiffBody();
 912                 if ( $body === false ) {
 913                         return false;
 914                 }
 915
 916                 $multi = $this->getMultiNotice();
 917                 // Display a message when the diff is empty
 918                 if ( $body === '' ) {
 919                         $notice .= '<div class="mw-diff-empty">' .
 920                                 $this->msg( 'diff-empty' )->parse() .
 921                                 "</div>\n";
 922                 }
 923
 924                 return $this->addHeader( $body, $otitle, $ntitle, $multi, $notice );
 925         }
 926
 927         /**
 928          * Get the diff table body, without header
 929          *
 930          * @return mixed (string/false)
 931          */
 932         public function getDiffBody() {
 933                 $this->mCacheHit = true;
 934                 // Check if the diff should be hidden from this user
 935                 if ( !$this->isContentOverridden ) {
 936                         if ( !$this->loadRevisionData() ) {
 937                                 return false;
 938                         } elseif ( $this->mOldRev &&
 939                                 !$this->mOldRev->userCan( Revision::DELETED_TEXT, $this->getUser() )
 940                         ) {
 941                                 return false;
 942                         } elseif ( $this->mNewRev &&
 943                                 !$this->mNewRev->userCan( Revision::DELETED_TEXT, $this->getUser() )
 944                         ) {
 945                                 return false;
 946                         }
 947                         // Short-circuit
 948                         if ( $this->mOldRev === false || ( $this->mOldRev && $this->mNewRev &&
 949                                 $this->mOldRev->getId() && $this->mOldRev->getId() == $this->mNewRev->getId() )
 950                         ) {
 951                                 if ( Hooks::run( 'DifferenceEngineShowEmptyOldContent', [ $this ] ) ) {
 952                                         return '';
 953                                 }
 954                         }
 955                 }
 956
 957                 // Cacheable?
 958                 $key = false;
 959                 $cache = ObjectCache::getMainWANInstance();
 960                 if ( $this->mOldid && $this->mNewid ) {
 961                         // Check if subclass is still using the old way
 962                         // for backwards-compatibility
 963                         $key = $this->getDiffBodyCacheKey();
 964                         if ( $key === null ) {
 965                                 $key = $cache->makeKey( ...$this->getDiffBodyCacheKeyParams() );
 966                         }
 967
 968                         // Try cache
 969                         if ( !$this->mRefreshCache ) {
 970                                 $difftext = $cache->get( $key );
 971                                 if ( $difftext ) {
 972                                         wfIncrStats( 'diff_cache.hit' );
 973                                         $difftext = $this->localiseDiff( $difftext );
 974                                         $difftext .= "\n<!-- diff cache key $key -->\n";
 975
 976                                         return $difftext;
 977                                 }
 978                         } // don't try to load but save the result
 979                 }
 980                 $this->mCacheHit = false;
 981
 982                 // Loadtext is permission safe, this just clears out the diff
 983                 if ( !$this->loadText() ) {
 984                         return false;
 985                 }
 986
 987                 $difftext = '';
 988                 // We've checked for revdelete at the beginning of this method; it's OK to ignore
 989                 // read permissions here.
 990                 $slotContents = $this->getSlotContents();
 991                 foreach ( $this->getSlotDiffRenderers() as $role => $slotDiffRenderer ) {
 992                         $slotDiff = $slotDiffRenderer->getDiff( $slotContents[$role]['old'],
 993                                 $slotContents[$role]['new'] );
 994                         if ( $slotDiff && $role !== 'main' ) {
 995                                 // TODO use human-readable role name at least
 996                                 $slotTitle = $role;
 997                                 $difftext .= $this->getSlotHeader( $slotTitle );
 998                         }
 999                         $difftext .= $slotDiff;
1000                 }
1001
1002                 // Avoid PHP 7.1 warning from passing $this by reference
1003                 $diffEngine = $this;
1004
1005                 // Save to cache for 7 days
1006                 if ( !Hooks::run( 'AbortDiffCache', [ &$diffEngine ] ) ) {
1007                         wfIncrStats( 'diff_cache.uncacheable' );
1008                 } elseif ( $key !== false && $difftext !== false ) {
1009                         wfIncrStats( 'diff_cache.miss' );
1010                         $cache->set( $key, $difftext, 7 * 86400 );
1011                 } else {
1012                         wfIncrStats( 'diff_cache.uncacheable' );
1013                 }
1014                 // localise line numbers and title attribute text
1015                 if ( $difftext !== false ) {
1016                         $difftext = $this->localiseDiff( $difftext );
1017                 }
1018
1019                 return $difftext;
1020         }
1021
1022         /**
1023          * Get a slot header for inclusion in a diff body (as a table row).
1024          *
1025          * @param string $headerText The text of the header
1026          * @return string
1027          *
1028          */
1029         protected function getSlotHeader( $headerText ) {
1030                 // The old revision is missing on oldid=<first>&diff=prev; only 2 columns in that case.
1031                 $columnCount = $this->mOldRev ? 4 : 2;
1032                 $userLang = $this->getLanguage()->getHtmlCode();
1033                 return Html::rawElement( 'tr', [ 'class' => 'mw-diff-slot-header', 'lang' => $userLang ],
1034                         Html::element( 'th', [ 'colspan' => $columnCount ], $headerText ) );
1035         }
1036
1037         /**
1038          * Returns the cache key for diff body text or content.
1039          *
1040          * @deprecated since 1.31, use getDiffBodyCacheKeyParams() instead
1041          * @since 1.23
1042          *
1043          * @throws MWException
1044          * @return string|null
1045          */
1046         protected function getDiffBodyCacheKey() {
1047                 return null;
1048         }
1049
1050         /**
1051          * Get the cache key parameters
1052          *
1053          * Subclasses can replace the first element in the array to something
1054          * more specific to the type of diff (e.g. "inline-diff"), or append
1055          * if the cache should vary on more things. Overriding entirely should
1056          * be avoided.
1057          *
1058          * @since 1.31
1059          *
1060          * @return array
1061          * @throws MWException
1062          */
1063         protected function getDiffBodyCacheKeyParams() {
1064                 if ( !$this->mOldid || !$this->mNewid ) {
1065                         throw new MWException( 'mOldid and mNewid must be set to get diff cache key.' );
1066                 }
1067
1068                 $engine = $this->getEngine();
1069                 $params = [
1070                         'diff',
1071                         $engine,
1072                         self::DIFF_VERSION,
1073                         "old-{$this->mOldid}",
1074                         "rev-{$this->mNewid}"
1075                 ];
1076
1077                 if ( $engine === 'wikidiff2' ) {
1078                         $params[] = phpversion( 'wikidiff2' );
1079                         $params[] = $this->getConfig()->get( 'WikiDiff2MovedParagraphDetectionCutoff' );
1080                 }
1081
1082                 if ( !$this->isSlotDiffRenderer ) {
1083                         foreach ( $this->getSlotDiffRenderers() as $slotDiffRenderer ) {
1084                                 $params = array_merge( $params, $slotDiffRenderer->getExtraCacheKeys() );
1085                         }
1086                 }
1087
1088                 return $params;
1089         }
1090
1091         /**
1092          * Implements DifferenceEngineSlotDiffRenderer::getExtraCacheKeys(). Only used when
1093          * DifferenceEngine is wrapped in DifferenceEngineSlotDiffRenderer.
1094          * @return array
1095          * @internal for use by DifferenceEngineSlotDiffRenderer only
1096          * @deprecated
1097          */
1098         public function getExtraCacheKeys() {
1099                 // This method is called when the DifferenceEngine is used for a slot diff. We only care
1100                 // about special things, not the revision IDs, which are added to the cache key by the
1101                 // page-level DifferenceEngine, and which might not have a valid value for this object.
1102                 $this->mOldid = 123456789;
1103                 $this->mNewid = 987654321;
1104
1105                 // This will repeat a bunch of unnecessary key fields for each slot. Not nice but harmless.
1106                 $cacheString = $this->getDiffBodyCacheKey();
1107                 if ( $cacheString ) {
1108                         return [ $cacheString ];
1109                 }
1110
1111                 $params = $this->getDiffBodyCacheKeyParams();
1112
1113                 // Try to get rid of the standard keys to keep the cache key human-readable:
1114                 // call the getDiffBodyCacheKeyParams implementation of the base class, and if
1115                 // the child class includes the same keys, drop them.
1116                 // Uses an obscure PHP feature where static calls to non-static methods are allowed
1117                 // as long as we are already in a non-static method of the same class, and the call context
1118                 // ($this) will be inherited.
1119                 // phpcs:ignore Squiz.Classes.SelfMemberReference.NotUsed
1120                 $standardParams = DifferenceEngine::getDiffBodyCacheKeyParams();
1121                 if ( array_slice( $params, 0, count( $standardParams ) ) === $standardParams ) {
1122                         $params = array_slice( $params, count( $standardParams ) );
1123                 }
1124
1125                 return $params;
1126         }
1127
1128         /**
1129          * Generate a diff, no caching.
1130          *
1131          * @since 1.21
1132          *
1133          * @param Content $old Old content
1134          * @param Content $new New content
1135          *
1136          * @throws Exception If old or new content is not an instance of TextContent.
1137          * @return bool|string
1138          *
1139          * @deprecated since 1.32, use a SlotDiffRenderer instead.
1140          */
1141         public function generateContentDiffBody( Content $old, Content $new ) {
1142                 $slotDiffRenderer = $new->getContentHandler()->getSlotDiffRenderer( $this->getContext() );
1143                 if (
1144                         $slotDiffRenderer instanceof DifferenceEngineSlotDiffRenderer
1145                         && $this->isSlotDiffRenderer
1146                 ) {
1147                         // Oops, we are just about to enter an infinite loop (the slot-level DifferenceEngine
1148                         // called a DifferenceEngineSlotDiffRenderer that wraps the same DifferenceEngine class).
1149                         // This will happen when a content model has no custom slot diff renderer, it does have
1150                         // a custom difference engine, but that does not override this method.
1151                         throw new Exception( get_class( $this ) . ': could not maintain backwards compatibility. '
1152                                 . 'Please use a SlotDiffRenderer.' );
1153                 }
1154                 return $slotDiffRenderer->getDiff( $old, $new ) . $this->getDebugString();
1155         }
1156
1157         /**
1158          * Generate a diff, no caching
1159          *
1160          * @param string $otext Old text, must be already segmented
1161          * @param string $ntext New text, must be already segmented
1162          *
1163          * @throws Exception If content handling for text content is configured in a way
1164          *   that makes maintaining B/C hard.
1165          * @return bool|string
1166          *
1167          * @deprecated since 1.32, use a TextSlotDiffRenderer instead.
1168          */
1169         public function generateTextDiffBody( $otext, $ntext ) {
1170                 $slotDiffRenderer = ContentHandler::getForModelID( CONTENT_MODEL_TEXT )
1171                         ->getSlotDiffRenderer( $this->getContext() );
1172                 if ( !( $slotDiffRenderer instanceof TextSlotDiffRenderer ) ) {
1173                         // Someone used the GetSlotDiffRenderer hook to replace the renderer.
1174                         // This is too unlikely to happen to bother handling properly.
1175                         throw new Exception( 'The slot diff renderer for text content should be a '
1176                                 . 'TextSlotDiffRenderer subclass' );
1177                 }
1178                 return $slotDiffRenderer->getTextDiff( $otext, $ntext ) . $this->getDebugString();
1179         }
1180
1181         /**
1182          * Process $wgExternalDiffEngine and get a sane, usable engine
1183          *
1184          * @return bool|string 'wikidiff2', path to an executable, or false
1185          * @internal For use by this class and TextSlotDiffRenderer only.
1186          */
1187         public static function getEngine() {
1188                 global $wgExternalDiffEngine;
1189                 // We use the global here instead of Config because we write to the value,
1190                 // and Config is not mutable.
1191                 if ( $wgExternalDiffEngine == 'wikidiff' || $wgExternalDiffEngine == 'wikidiff3' ) {
1192                         wfDeprecated( "\$wgExternalDiffEngine = '{$wgExternalDiffEngine}'", '1.27' );
1193                         $wgExternalDiffEngine = false;
1194                 } elseif ( $wgExternalDiffEngine == 'wikidiff2' ) {
1195                         wfDeprecated( "\$wgExternalDiffEngine = '{$wgExternalDiffEngine}'", '1.32' );
1196                         $wgExternalDiffEngine = false;
1197                 } elseif ( !is_string( $wgExternalDiffEngine ) && $wgExternalDiffEngine !== false ) {
1198                         // And prevent people from shooting themselves in the foot...
1199                         wfWarn( '$wgExternalDiffEngine is set to a non-string value, forcing it to false' );
1200                         $wgExternalDiffEngine = false;
1201                 }
1202
1203                 if ( is_string( $wgExternalDiffEngine ) && is_executable( $wgExternalDiffEngine ) ) {
1204                         return $wgExternalDiffEngine;
1205                 } elseif ( $wgExternalDiffEngine === false && function_exists( 'wikidiff2_do_diff' ) ) {
1206                         return 'wikidiff2';
1207                 } else {
1208                         // Native PHP
1209                         return false;
1210                 }
1211         }
1212
1213         /**
1214          * Generates diff, to be wrapped internally in a logging/instrumentation
1215          *
1216          * @param string $otext Old text, must be already segmented
1217          * @param string $ntext New text, must be already segmented
1218          *
1219          * @throws Exception If content handling for text content is configured in a way
1220          *   that makes maintaining B/C hard.
1221          * @return bool|string
1222          *
1223          * @deprecated since 1.32, use a TextSlotDiffRenderer instead.
1224          */
1225         protected function textDiff( $otext, $ntext ) {
1226                 $slotDiffRenderer = ContentHandler::getForModelID( CONTENT_MODEL_TEXT )
1227                         ->getSlotDiffRenderer( $this->getContext() );
1228                 if ( !( $slotDiffRenderer instanceof TextSlotDiffRenderer ) ) {
1229                         // Someone used the GetSlotDiffRenderer hook to replace the renderer.
1230                         // This is too unlikely to happen to bother handling properly.
1231                         throw new Exception( 'The slot diff renderer for text content should be a '
1232                                 . 'TextSlotDiffRenderer subclass' );
1233                 }
1234                 return $slotDiffRenderer->getTextDiff( $otext, $ntext ) . $this->getDebugString();
1235         }
1236
1237         /**
1238          * Generate a debug comment indicating diff generating time,
1239          * server node, and generator backend.
1240          *
1241          * @param string $generator : What diff engine was used
1242          *
1243          * @return string
1244          */
1245         protected function debug( $generator = "internal" ) {
1246                 global $wgShowHostnames;
1247                 if ( !$this->enableDebugComment ) {
1248                         return '';
1249                 }
1250                 $data = [ $generator ];
1251                 if ( $wgShowHostnames ) {
1252                         $data[] = wfHostname();
1253                 }
1254                 $data[] = wfTimestamp( TS_DB );
1255
1256                 return "<!-- diff generator: " .
1257                         implode( " ", array_map( "htmlspecialchars", $data ) ) .
1258                         " -->\n";
1259         }
1260
1261         private function getDebugString() {
1262                 $engine = self::getEngine();
1263                 if ( $engine === 'wikidiff2' ) {
1264                         return $this->debug( 'wikidiff2' );
1265                 } elseif ( $engine === false ) {
1266                         return $this->debug( 'native PHP' );
1267                 } else {
1268                         return $this->debug( "external $engine" );
1269                 }
1270         }
1271
1272         /**
1273          * Localise diff output
1274          *
1275          * @param string $text
1276          * @return string
1277          */
1278         private function localiseDiff( $text ) {
1279                 $text = $this->localiseLineNumbers( $text );
1280                 if ( $this->getEngine() === 'wikidiff2' &&
1281                         version_compare( phpversion( 'wikidiff2' ), '1.5.1', '>=' )
1282                 ) {
1283                         $text = $this->addLocalisedTitleTooltips( $text );
1284                 }
1285                 return $text;
1286         }
1287
1288         /**
1289          * Replace line numbers with the text in the user's language
1290          *
1291          * @param string $text
1292          *
1293          * @return mixed
1294          */
1295         public function localiseLineNumbers( $text ) {
1296                 return preg_replace_callback(
1297                         '/<!--LINE (\d+)-->/',
1298                         [ $this, 'localiseLineNumbersCb' ],
1299                         $text
1300                 );
1301         }
1302
1303         public function localiseLineNumbersCb( $matches ) {
1304                 if ( $matches[1] === '1' && $this->mReducedLineNumbers ) {
1305                         return '';
1306                 }
1307
1308                 return $this->msg( 'lineno' )->numParams( $matches[1] )->escaped();
1309         }
1310
1311         /**
1312          * Add title attributes for tooltips on moved paragraph indicators
1313          *
1314          * @param string $text
1315          * @return string
1316          */
1317         private function addLocalisedTitleTooltips( $text ) {
1318                 return preg_replace_callback(
1319                         '/class="mw-diff-movedpara-(left|right)"/',
1320                         [ $this, 'addLocalisedTitleTooltipsCb' ],
1321                         $text
1322                 );
1323         }
1324
1325         /**
1326          * @param array $matches
1327          * @return string
1328          */
1329         private function addLocalisedTitleTooltipsCb( array $matches ) {
1330                 $key = $matches[1] === 'right' ?
1331                         'diff-paragraph-moved-toold' :
1332                         'diff-paragraph-moved-tonew';
1333                 return $matches[0] . ' title="' . $this->msg( $key )->escaped() . '"';
1334         }
1335
1336         /**
1337          * If there are revisions between the ones being compared, return a note saying so.
1338          *
1339          * @return string
1340          */
1341         public function getMultiNotice() {
1342                 // The notice only make sense if we are diffing two saved revisions of the same page.
1343                 if (
1344                         !$this->mOldRev || !$this->mNewRev
1345                         || !$this->mOldPage || !$this->mNewPage
1346                         || !$this->mOldPage->equals( $this->mNewPage )
1347                 ) {
1348                         return '';
1349                 }
1350
1351                 if ( $this->mOldRev->getTimestamp() > $this->mNewRev->getTimestamp() ) {
1352                         $oldRev = $this->mNewRev; // flip
1353                         $newRev = $this->mOldRev; // flip
1354                 } else { // normal case
1355                         $oldRev = $this->mOldRev;
1356                         $newRev = $this->mNewRev;
1357                 }
1358
1359                 // Sanity: don't show the notice if too many rows must be scanned
1360                 // @todo show some special message for that case
1361                 $nEdits = $this->mNewPage->countRevisionsBetween( $oldRev, $newRev, 1000 );
1362                 if ( $nEdits > 0 && $nEdits <= 1000 ) {
1363                         $limit = 100; // use diff-multi-manyusers if too many users
1364                         $users = $this->mNewPage->getAuthorsBetween( $oldRev, $newRev, $limit );
1365                         $numUsers = count( $users );
1366
1367                         if ( $numUsers == 1 && $users[0] == $newRev->getUserText( Revision::RAW ) ) {
1368                                 $numUsers = 0; // special case to say "by the same user" instead of "by one other user"
1369                         }
1370
1371                         return self::intermediateEditsMsg( $nEdits, $numUsers, $limit );
1372                 }
1373
1374                 return ''; // nothing
1375         }
1376
1377         /**
1378          * Get a notice about how many intermediate edits and users there are
1379          *
1380          * @param int $numEdits
1381          * @param int $numUsers
1382          * @param int $limit
1383          *
1384          * @return string
1385          */
1386         public static function intermediateEditsMsg( $numEdits, $numUsers, $limit ) {
1387                 if ( $numUsers === 0 ) {
1388                         $msg = 'diff-multi-sameuser';
1389                 } elseif ( $numUsers > $limit ) {
1390                         $msg = 'diff-multi-manyusers';
1391                         $numUsers = $limit;
1392                 } else {
1393                         $msg = 'diff-multi-otherusers';
1394                 }
1395
1396                 return wfMessage( $msg )->numParams( $numEdits, $numUsers )->parse();
1397         }
1398
1399         /**
1400          * Get a header for a specified revision.
1401          *
1402          * @param Revision $rev
1403          * @param string $complete 'complete' to get the header wrapped depending
1404          *        the visibility of the revision and a link to edit the page.
1405          *
1406          * @return string HTML fragment
1407          */
1408         public function getRevisionHeader( Revision $rev, $complete = '' ) {
1409                 $lang = $this->getLanguage();
1410                 $user = $this->getUser();
1411                 $revtimestamp = $rev->getTimestamp();
1412                 $timestamp = $lang->userTimeAndDate( $revtimestamp, $user );
1413                 $dateofrev = $lang->userDate( $revtimestamp, $user );
1414                 $timeofrev = $lang->userTime( $revtimestamp, $user );
1415
1416                 $header = $this->msg(
1417                         $rev->isCurrent() ? 'currentrev-asof' : 'revisionasof',
1418                         $timestamp,
1419                         $dateofrev,
1420                         $timeofrev
1421                 )->escaped();
1422
1423                 if ( $complete !== 'complete' ) {
1424                         return $header;
1425                 }
1426
1427                 $title = $rev->getTitle();
1428
1429                 $header = Linker::linkKnown( $title, $header, [],
1430                         [ 'oldid' => $rev->getId() ] );
1431
1432                 if ( $rev->userCan( Revision::DELETED_TEXT, $user ) ) {
1433                         $editQuery = [ 'action' => 'edit' ];
1434                         if ( !$rev->isCurrent() ) {
1435                                 $editQuery['oldid'] = $rev->getId();
1436                         }
1437
1438                         $key = $title->quickUserCan( 'edit', $user ) ? 'editold' : 'viewsourceold';
1439                         $msg = $this->msg( $key )->escaped();
1440                         $editLink = $this->msg( 'parentheses' )->rawParams(
1441                                 Linker::linkKnown( $title, $msg, [], $editQuery ) )->escaped();
1442                         $header .= ' ' . Html::rawElement(
1443                                 'span',
1444                                 [ 'class' => 'mw-diff-edit' ],
1445                                 $editLink
1446                         );
1447                         if ( $rev->isDeleted( Revision::DELETED_TEXT ) ) {
1448                                 $header = Html::rawElement(
1449                                         'span',
1450                                         [ 'class' => 'history-deleted' ],
1451                                         $header
1452                                 );
1453                         }
1454                 } else {
1455                         $header = Html::rawElement( 'span', [ 'class' => 'history-deleted' ], $header );
1456                 }
1457
1458                 return $header;
1459         }
1460
1461         /**
1462          * Add the header to a diff body
1463          *
1464          * @param string $diff Diff body
1465          * @param string $otitle Old revision header
1466          * @param string $ntitle New revision header
1467          * @param string $multi Notice telling user that there are intermediate
1468          *   revisions between the ones being compared
1469          * @param string $notice Other notices, e.g. that user is viewing deleted content
1470          *
1471          * @return string
1472          */
1473         public function addHeader( $diff, $otitle, $ntitle, $multi = '', $notice = '' ) {
1474                 // shared.css sets diff in interface language/dir, but the actual content
1475                 // is often in a different language, mostly the page content language/dir
1476                 $header = Html::openElement( 'table', [
1477                         'class' => [ 'diff', 'diff-contentalign-' . $this->getDiffLang()->alignStart() ],
1478                         'data-mw' => 'interface',
1479                 ] );
1480                 $userLang = htmlspecialchars( $this->getLanguage()->getHtmlCode() );
1481
1482                 if ( !$diff && !$otitle ) {
1483                         $header .= "
1484                         <tr class=\"diff-title\" lang=\"{$userLang}\">
1485                         <td class=\"diff-ntitle\">{$ntitle}</td>
1486                         </tr>";
1487                         $multiColspan = 1;
1488                 } else {
1489                         if ( $diff ) { // Safari/Chrome show broken output if cols not used
1490                                 $header .= "
1491                                 <col class=\"diff-marker\" />
1492                                 <col class=\"diff-content\" />
1493                                 <col class=\"diff-marker\" />
1494                                 <col class=\"diff-content\" />";
1495                                 $colspan = 2;
1496                                 $multiColspan = 4;
1497                         } else {
1498                                 $colspan = 1;
1499                                 $multiColspan = 2;
1500                         }
1501                         if ( $otitle || $ntitle ) {
1502                                 $header .= "
1503                                 <tr class=\"diff-title\" lang=\"{$userLang}\">
1504                                 <td colspan=\"$colspan\" class=\"diff-otitle\">{$otitle}</td>
1505                                 <td colspan=\"$colspan\" class=\"diff-ntitle\">{$ntitle}</td>
1506                                 </tr>";
1507                         }
1508                 }
1509
1510                 if ( $multi != '' ) {
1511                         $header .= "<tr><td colspan=\"{$multiColspan}\" " .
1512                                 "class=\"diff-multi\" lang=\"{$userLang}\">{$multi}</td></tr>";
1513                 }
1514                 if ( $notice != '' ) {
1515                         $header .= "<tr><td colspan=\"{$multiColspan}\" " .
1516                                 "class=\"diff-notice\" lang=\"{$userLang}\">{$notice}</td></tr>";
1517                 }
1518
1519                 return $header . $diff . "</table>";
1520         }
1521
1522         /**
1523          * Use specified text instead of loading from the database
1524          * @param Content $oldContent
1525          * @param Content $newContent
1526          * @since 1.21
1527          * @deprecated since 1.32, use setRevisions or ContentHandler::getSlotDiffRenderer.
1528          */
1529         public function setContent( Content $oldContent, Content $newContent ) {
1530                 $this->mOldContent = $oldContent;
1531                 $this->mNewContent = $newContent;
1532
1533                 $this->mTextLoaded = 2;
1534                 $this->mRevisionsLoaded = true;
1535                 $this->isContentOverridden = true;
1536                 $this->slotDiffRenderers = null;
1537         }
1538
1539         /**
1540          * Use specified text instead of loading from the database.
1541          * @param RevisionRecord|null $oldRevision
1542          * @param RevisionRecord $newRevision
1543          */
1544         public function setRevisions(
1545                 RevisionRecord $oldRevision = null, RevisionRecord $newRevision
1546         ) {
1547                 if ( $oldRevision ) {
1548                         $this->mOldRev = new Revision( $oldRevision );
1549                         $this->mOldid = $oldRevision->getId();
1550                         $this->mOldPage = Title::newFromLinkTarget( $oldRevision->getPageAsLinkTarget() );
1551                         // This method is meant for edit diffs and such so there is no reason to provide a
1552                         // revision that's not readable to the user, but check it just in case.
1553                         $this->mOldContent = $oldRevision ? $oldRevision->getContent( 'main',
1554                                 RevisionRecord::FOR_THIS_USER, $this->getUser() ) : null;
1555                 } else {
1556                         $this->mOldRev = $this->mOldid = $this->mOldPage = null;
1557                 }
1558                 $this->mNewRev = new Revision( $newRevision );
1559                 $this->mNewid = $newRevision->getId();
1560                 $this->mNewPage = Title::newFromLinkTarget( $newRevision->getPageAsLinkTarget() );
1561                 $this->mNewContent = $newRevision->getContent( 'main',
1562                         RevisionRecord::FOR_THIS_USER, $this->getUser() );
1563
1564                 $this->mRevisionsIdsLoaded = $this->mRevisionsLoaded = true;
1565                 $this->mTextLoaded = !!$oldRevision + 1;
1566                 $this->isContentOverridden = false;
1567                 $this->slotDiffRenderers = null;
1568         }
1569
1570         /**
1571          * Set the language in which the diff text is written
1572          *
1573          * @param Language $lang
1574          * @since 1.19
1575          */
1576         public function setTextLanguage( $lang ) {
1577                 if ( !$lang instanceof Language ) {
1578                         wfDeprecated( __METHOD__ . ' with other type than Language for $lang', '1.32' );
1579                 }
1580                 $this->mDiffLang = wfGetLangObj( $lang );
1581         }
1582
1583         /**
1584          * Maps a revision pair definition as accepted by DifferenceEngine constructor
1585          * to a pair of actual integers representing revision ids.
1586          *
1587          * @param int $old Revision id, e.g. from URL parameter 'oldid'
1588          * @param int|string $new Revision id or strings 'next' or 'prev', e.g. from URL parameter 'diff'
1589          *
1590          * @return int[] List of two revision ids, older first, later second.
1591          *     Zero signifies invalid argument passed.
1592          *     false signifies that there is no previous/next revision ($old is the oldest/newest one).
1593          */
1594         public function mapDiffPrevNext( $old, $new ) {
1595                 if ( $new === 'prev' ) {
1596                         // Show diff between revision $old and the previous one. Get previous one from DB.
1597                         $newid = intval( $old );
1598                         $oldid = $this->getTitle()->getPreviousRevisionID( $newid );
1599                 } elseif ( $new === 'next' ) {
1600                         // Show diff between revision $old and the next one. Get next one from DB.
1601                         $oldid = intval( $old );
1602                         $newid = $this->getTitle()->getNextRevisionID( $oldid );
1603                 } else {
1604                         $oldid = intval( $old );
1605                         $newid = intval( $new );
1606                 }
1607
1608                 return [ $oldid, $newid ];
1609         }
1610
1611         /**
1612          * Load revision IDs
1613          */
1614         private function loadRevisionIds() {
1615                 if ( $this->mRevisionsIdsLoaded ) {
1616                         return;
1617                 }
1618
1619                 $this->mRevisionsIdsLoaded = true;
1620
1621                 $old = $this->mOldid;
1622                 $new = $this->mNewid;
1623
1624                 list( $this->mOldid, $this->mNewid ) = self::mapDiffPrevNext( $old, $new );
1625                 if ( $new === 'next' && $this->mNewid === false ) {
1626                         # if no result, NewId points to the newest old revision. The only newer
1627                         # revision is cur, which is "0".
1628                         $this->mNewid = 0;
1629                 }
1630
1631                 Hooks::run(
1632                         'NewDifferenceEngine',
1633                         [ $this->getTitle(), &$this->mOldid, &$this->mNewid, $old, $new ]
1634                 );
1635         }
1636
1637         /**
1638          * Load revision metadata for the specified articles. If newid is 0, then compare
1639          * the old article in oldid to the current article; if oldid is 0, then
1640          * compare the current article to the immediately previous one (ignoring the
1641          * value of newid).
1642          *
1643          * If oldid is false, leave the corresponding revision object set
1644          * to false. This is impossible via ordinary user input, and is provided for
1645          * API convenience.
1646          *
1647          * @return bool Whether both revisions were loaded successfully.
1648          */
1649         public function loadRevisionData() {
1650                 if ( $this->mRevisionsLoaded ) {
1651                         return $this->isContentOverridden || $this->mNewRev && $this->mOldRev;
1652                 }
1653
1654                 // Whether it succeeds or fails, we don't want to try again
1655                 $this->mRevisionsLoaded = true;
1656
1657                 $this->loadRevisionIds();
1658
1659                 // Load the new revision object
1660                 if ( $this->mNewid ) {
1661                         $this->mNewRev = Revision::newFromId( $this->mNewid );
1662                 } else {
1663                         $this->mNewRev = Revision::newFromTitle(
1664                                 $this->getTitle(),
1665                                 false,
1666                                 Revision::READ_NORMAL
1667                         );
1668                 }
1669
1670                 if ( !$this->mNewRev instanceof Revision ) {
1671                         return false;
1672                 }
1673
1674                 // Update the new revision ID in case it was 0 (makes life easier doing UI stuff)
1675                 $this->mNewid = $this->mNewRev->getId();
1676                 if ( $this->mNewid ) {
1677                         $this->mNewPage = $this->mNewRev->getTitle();
1678                 } else {
1679                         $this->mNewPage = null;
1680                 }
1681
1682                 // Load the old revision object
1683                 $this->mOldRev = false;
1684                 if ( $this->mOldid ) {
1685                         $this->mOldRev = Revision::newFromId( $this->mOldid );
1686                 } elseif ( $this->mOldid === 0 ) {
1687                         $rev = $this->mNewRev->getPrevious();
1688                         if ( $rev ) {
1689                                 $this->mOldid = $rev->getId();
1690                                 $this->mOldRev = $rev;
1691                         } else {
1692                                 // No previous revision; mark to show as first-version only.
1693                                 $this->mOldid = false;
1694                                 $this->mOldRev = false;
1695                         }
1696                 } /* elseif ( $this->mOldid === false ) leave mOldRev false; */
1697
1698                 if ( is_null( $this->mOldRev ) ) {
1699                         return false;
1700                 }
1701
1702                 if ( $this->mOldRev && $this->mOldRev->getId() ) {
1703                         $this->mOldPage = $this->mOldRev->getTitle();
1704                 } else {
1705                         $this->mOldPage = null;
1706                 }
1707
1708                 // Load tags information for both revisions
1709                 $dbr = wfGetDB( DB_REPLICA );
1710                 if ( $this->mOldid !== false ) {
1711                         $this->mOldTags = $dbr->selectField(
1712                                 'tag_summary',
1713                                 'ts_tags',
1714                                 [ 'ts_rev_id' => $this->mOldid ],
1715                                 __METHOD__
1716                         );
1717                 } else {
1718                         $this->mOldTags = false;
1719                 }
1720                 $this->mNewTags = $dbr->selectField(
1721                         'tag_summary',
1722                         'ts_tags',
1723                         [ 'ts_rev_id' => $this->mNewid ],
1724                         __METHOD__
1725                 );
1726
1727                 return true;
1728         }
1729
1730         /**
1731          * Load the text of the revisions, as well as revision data.
1732          *
1733          * @return bool Whether the content of both revisions could be loaded successfully.
1734          */
1735         public function loadText() {
1736                 if ( $this->mTextLoaded == 2 ) {
1737                         return $this->loadRevisionData() && $this->mOldContent && $this->mNewContent;
1738                 }
1739
1740                 // Whether it succeeds or fails, we don't want to try again
1741                 $this->mTextLoaded = 2;
1742
1743                 if ( !$this->loadRevisionData() ) {
1744                         return false;
1745                 }
1746
1747                 if ( $this->mOldRev ) {
1748                         $this->mOldContent = $this->mOldRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1749                         if ( $this->mOldContent === null ) {
1750                                 return false;
1751                         }
1752                 }
1753
1754                 if ( $this->mNewRev ) {
1755                         $this->mNewContent = $this->mNewRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1756                         Hooks::run( 'DifferenceEngineLoadTextAfterNewContentIsLoaded', [ $this ] );
1757                         if ( $this->mNewContent === null ) {
1758                                 return false;
1759                         }
1760                 }
1761
1762                 return true;
1763         }
1764
1765         /**
1766          * Load the text of the new revision, not the old one
1767          *
1768          * @return bool Whether the content of the new revision could be loaded successfully.
1769          */
1770         public function loadNewText() {
1771                 if ( $this->mTextLoaded >= 1 ) {
1772                         return $this->loadRevisionData();
1773                 }
1774
1775                 $this->mTextLoaded = 1;
1776
1777                 if ( !$this->loadRevisionData() ) {
1778                         return false;
1779                 }
1780
1781                 $this->mNewContent = $this->mNewRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
1782
1783                 Hooks::run( 'DifferenceEngineAfterLoadNewText', [ $this ] );
1784
1785                 return true;
1786         }
1787
1788 }