includes/ContentHandler.php

   1 <?php
   2
   3 class MWContentSerializationException extends MWException {
   4
   5 }
   6
   7
   8 /**
   9  * A content handler knows how do deal with a specific type of content on a wiki page.
  10  * Content is stored in the database in a serialized form (using a serialization format aka mime type)
  11  * and is be unserialized into it's native PHP represenation (the content model), which is wrappe in
  12  * an instance of the appropriate subclass of Content.
  13  *
  14  * ContentHandler instances are stateless singletons that serve, among other things, as a factory for
  15  * Content objects. Generally, there is one subclass of ContentHandler and one subclass of Content
  16  * for every type of content model.
  17  *
  18  * Some content types have a flat model, that is, their native represenation is the
  19  * same as their serialized form. Examples would be JavaScript and CSS code. As of now,
  20  * this also applies to wikitext (mediawiki's default content type), but wikitext
  21  * content may be represented by a DOM or AST structure in the future.
  22  */
  23 abstract class ContentHandler {
  24
  25         /**
  26          * Conveniance function for getting flat text from a Content object. This should only
  27          * be used in the context of backwards compatibility with code that is not yet able
  28          * to handle Content objects!
  29          *
  30          * If $content is null, this method returns the empty string.
  31          *
  32          * If $content is an instance of TextContent, this method returns the flat text as returned by $content->getNativeData().
  33          *
  34          * If $content is not a TextContent object, the bahaviour of this method depends on the global $wgContentHandlerTextFallback:
  35          * * If $wgContentHandlerTextFallback is 'fail' and $content is not a TextContent object, an MWException is thrown.
  36          * * If $wgContentHandlerTextFallback is 'serialize' and $content is not a TextContent object, $content->serialize()
  37          * is called to get a string form of the content.
  38          * * If $wgContentHandlerTextFallback is 'ignore' and $content is not a TextContent object, this method returns null.
  39          * * otherwise, the behaviour is undefined.
  40          *
  41          * @static
  42          * @param Content|null $content
  43          * @return null|string the textual form of $content, if available
  44          * @throws MWException if $content is not an instance of TextContent and $wgContentHandlerTextFallback was set to 'fail'.
  45          */
  46         public static function getContentText( Content $content = null ) {
  47                 global $wgContentHandlerTextFallback;
  48
  49                 if ( is_null( $content ) ) {
  50                         return '';
  51                 }
  52
  53                 if ( $content instanceof TextContent ) {
  54                         return $content->getNativeData();
  55                 }
  56
  57                 if ( $wgContentHandlerTextFallback == 'fail' ) {
  58                         throw new MWException( "Attempt to get text from Content with model " . $content->getModelName() );
  59                 }
  60
  61                 if ( $wgContentHandlerTextFallback == 'serialize' ) {
  62                         return $content->serialize();
  63                 }
  64
  65                 return null;
  66         }
  67
  68         /**
  69          * Conveniance function for creating a Content object from a given textual representation.
  70          *
  71          * $text will be deserialized into a Content object of the model specified by $modelName (or,
  72          * if that is not given, $title->getContentModelName()) using the given format.
  73          *
  74          * @static
  75          * @param string $text the textual represenation, will be unserialized to create the Content object
  76          * @param Title $title the title of the page this text belongs to, required as a context for deserialization
  77          * @param null|String $modelName the model to deserialize to. If not provided, $title->getContentModelName() is used.
  78          * @param null|String $format the format to use for deserialization. If not given, the model's default format is used.
  79          *
  80          * @return Content a Content object representing $text
  81          * @throw MWException if $model or $format is not supported or if $text can not be unserialized using $format.
  82          */
  83         public static function makeContent( $text, Title $title, $modelName = null, $format = null ) {
  84
  85                 if ( is_null( $modelName ) ) {
  86                         $modelName = $title->getContentModelName();
  87                 }
  88
  89                 $handler = ContentHandler::getForModelName( $modelName );
  90                 return $handler->unserializeContent( $text, $format );
  91         }
  92
  93         /**
  94          * Returns the name of the default content model to be used for the page with the given title.
  95          *
  96          * Note: There should rarely be need to call this method directly.
  97          * To determine the actual content model for a given page, use Title::getContentModelName().
  98          *
  99          * Which model is to be used per default for the page is determined based on several factors:
 100          * * The global setting $wgNamespaceContentModels specifies a content model per namespace.
 101          * * The hook DefaultModelFor may be used to override the page's default model.
 102          * * Pages in NS_MEDIAWIKI and NS_USER default to the CSS or JavaScript model if they end in .js or .css, respectively.
 103          * * Pages in NS_MEDIAWIKI default to the wikitext model otherwise.
 104          * * The hook TitleIsCssOrJsPage may be used to force a page to use the CSS or JavaScript model if they end in .js or .css, respectively.
 105          * * The hook TitleIsWikitextPage may be used to force a page to use the wikitext model.
 106          *
 107          * If none of the above applies, the wikitext model is used.
 108          *
 109          * Note: this is used by, and may thus not use, Title::getContentModelName()
 110          *
 111          * @static
 112          * @param Title $title
 113          * @return null|string default model name for the page given by $title
 114          */
 115         public static function getDefaultModelFor( Title $title ) {
 116                 global $wgNamespaceContentModels;
 117
 118                 // NOTE: this method must not rely on $title->getContentModelName() directly or indirectly,
 119                 //       because it is used to initialized the mContentModelName memebr.
 120
 121                 $ns = $title->getNamespace();
 122
 123                 $ext = false;
 124                 $m = null;
 125                 $model = null;
 126
 127                 if ( !empty( $wgNamespaceContentModels[ $ns ] ) ) {
 128                         $model = $wgNamespaceContentModels[ $ns ];
 129                 }
 130
 131                 // hook can determin default model
 132                 if ( !wfRunHooks( 'DefaultModelFor', array( $title, &$model ) ) ) { #FIXME: document new hook!
 133                         if ( !is_null( $model ) ) {
 134                                 return $model;
 135                         }
 136                 }
 137
 138                 // Could this page contain custom CSS or JavaScript, based on the title?
 139                 $isCssOrJsPage = NS_MEDIAWIKI == $ns && preg_match( '!\.(css|js)$!u', $title->getText(), $m );
 140                 if ( $isCssOrJsPage ) {
 141                         $ext = $m[1];
 142                 }
 143
 144                 // hook can force js/css
 145                 wfRunHooks( 'TitleIsCssOrJsPage', array( $title, &$isCssOrJsPage ) );
 146
 147                 // Is this a .css subpage of a user page?
 148                 $isJsCssSubpage = NS_USER == $ns && !$isCssOrJsPage && preg_match( "/\\/.*\\.(js|css)$/", $title->getText(), $m );
 149                 if ( $isJsCssSubpage ) {
 150                         $ext = $m[1];
 151                 }
 152
 153                 // is this wikitext, according to $wgNamespaceContentModels or the DefaultModelFor hook?
 154                 $isWikitext = is_null( $model ) || $model == CONTENT_MODEL_WIKITEXT;
 155                 $isWikitext = $isWikitext && !$isCssOrJsPage && !$isJsCssSubpage;
 156
 157                 // hook can override $isWikitext
 158                 wfRunHooks( 'TitleIsWikitextPage', array( $title, &$isWikitext ) );
 159
 160                 if ( !$isWikitext ) {
 161                         switch ( $ext ) {
 162                                 case 'js':
 163                                         return CONTENT_MODEL_JAVASCRIPT;
 164                                 case 'css':
 165                                         return CONTENT_MODEL_CSS;
 166                                 default:
 167                                         return is_null( $model ) ? CONTENT_MODEL_TEXT : $model;
 168                         }
 169                 }
 170
 171                 // we established that is must be wikitext
 172
 173                 return CONTENT_MODEL_WIKITEXT;
 174         }
 175
 176         /**
 177          * returns the appropriate ContentHandler singleton for the given title
 178          *
 179          * @static
 180          * @param Title $title
 181          * @return ContentHandler
 182          */
 183         public static function getForTitle( Title $title ) {
 184                 $modelName = $title->getContentModelName();
 185                 return ContentHandler::getForModelName( $modelName );
 186         }
 187
 188         /**
 189          * returns the appropriate ContentHandler singleton for the given Content object
 190          *
 191          * @static
 192          * @param Content $content
 193          * @return ContentHandler
 194          */
 195         public static function getForContent( Content $content ) {
 196                 $modelName = $content->getModelName();
 197                 return ContentHandler::getForModelName( $modelName );
 198         }
 199
 200         /**
 201          * returns the ContentHandler singleton for the given model name. Use the CONTENT_MODEL_XXX constants to
 202          * identify the desired content model.
 203          *
 204          * ContentHandler singletons are take from the global $wgContentHandlers array. Keys in that array are
 205          * model names, the values are either ContentHandler singleton objects, or strings specifying the appropriate
 206          * subclass of ContentHandler.
 207          *
 208          * If a class name in encountered when looking up the singleton for a given model name, the class is
 209          * instantiated and the class name is replaced by te resulting singleton in $wgContentHandlers.
 210          *
 211          * If no ContentHandler is defined for the desired $modelName, the ContentHandler may be provided by the
 212          * a ContentHandlerForModelName hook. if no Contenthandler can be determined, an MWException is raised.
 213          *
 214          * @static
 215          * @param $modelName String the name of the content model for which to get a handler. Use CONTENT_MODEL_XXX constants.
 216          * @return ContentHandler the ContentHandler singleton for handling the model given by $modelName
 217          * @throws MWException if no handler is known for $modelName.
 218          */
 219         public static function getForModelName( $modelName ) {
 220                 global $wgContentHandlers;
 221
 222                 if ( empty( $wgContentHandlers[$modelName] ) ) {
 223                         $handler = null;
 224
 225                         // FIXME: document new hook
 226                         wfRunHooks( 'ContentHandlerForModelName', array( $modelName, &$handler ) );
 227
 228                         if ( $handler ) { // NOTE: may be a string or an object, either is fine!
 229                                 $wgContentHandlers[$modelName] = $handler;
 230                         } else {
 231                                 throw new MWException( "No handler for model $modelName registered in \$wgContentHandlers" );
 232                         }
 233                 }
 234
 235                 if ( is_string( $wgContentHandlers[$modelName] ) ) {
 236                         $class = $wgContentHandlers[$modelName];
 237                         $wgContentHandlers[$modelName] = new $class( $modelName );
 238                 }
 239
 240                 return $wgContentHandlers[$modelName];
 241         }
 242
 243         // ----------------------------------------------------------------------------------------------------------
 244
 245         /**
 246          * Constructor, initializing the ContentHandler instance with it's model name and a list of supported formats.
 247          * Values for the parameters are typically provided as literals by subclasses' constructors.
 248          *
 249          * @param String $modelName (use CONTENT_MODEL_XXX constants).
 250          * @param array $formats list for supported serialization formats (typically as MIME types)
 251          */
 252         public function __construct( $modelName, $formats ) {
 253                 $this->mModelName = $modelName;
 254                 $this->mSupportedFormats = $formats;
 255         }
 256
 257
 258         /**
 259          * Serializes Content object of the type supported by this ContentHandler.
 260          *
 261          * @abstract
 262          * @param Content $content the Content object to serialize
 263          * @param null $format the desired serialization format
 264          * @return String serialized form of the content
 265          */
 266         public abstract function serializeContent( Content $content, $format = null );
 267
 268         /**
 269          * Unserializes a Content object of the type supported by this ContentHandler.
 270          *
 271          * @abstract
 272          * @param $blob String serialized form of the content
 273          * @param null $format the format used for serialization
 274          * @return Content the Content object created by deserializing $blob
 275          */
 276         public abstract function unserializeContent( $blob, $format = null );
 277
 278         /**
 279          * Creates an empty Content object of the type supported by this ContentHandler.
 280          *
 281          * @return Content
 282          */
 283         public abstract function makeEmptyContent();
 284
 285         /**
 286          * Returns the model name that identifies the content model this ContentHandler can handle.
 287          * Use with the CONTENT_MODEL_XXX constants.
 288          *
 289          * @return String the model name
 290          */
 291         public function getModelName() {
 292                 return $this->mModelName;
 293         }
 294
 295         /**
 296          * Throws an MWException if $modelName is not the content model handeled by this ContentHandler.
 297          *
 298          * @param String $modelName the model name to check
 299          */
 300         protected function checkModelName( $modelName ) {
 301                 if ( $modelName !== $this->mModelName ) {
 302                         throw new MWException( "Bad content model: expected " . $this->mModelName . " but got found " . $modelName );
 303                 }
 304         }
 305
 306         /**
 307          * Returns a list of serialization formats supported by the serializeContent() and unserializeContent() methods of
 308          * this ContentHandler.
 309          *
 310          * @return array of serialization formats as MIME type like strings
 311          */
 312         public function getSupportedFormats() {
 313                 return $this->mSupportedFormats;
 314         }
 315
 316         /**
 317          * The format used for serialization/deserialization per default by this ContentHandler.
 318          *
 319          * This default implementation will return the first element of the array of formats
 320          * that was passed to the constructor.
 321          *
 322          * @return String the name of the default serialiozation format as a MIME type
 323          */
 324         public function getDefaultFormat() {
 325                 return $this->mSupportedFormats[0];
 326         }
 327
 328         /**
 329          * Returns true if $format is a serialization format supported by this ContentHandler,
 330          * and false otherwise.
 331          *
 332          * Note that if $format is null, this method always returns true, because null
 333          * means "use the default format".
 334          *
 335          * @param String $format the serialization format to check
 336          * @return bool
 337          */
 338         public function isSupportedFormat( $format ) {
 339
 340                 if ( !$format ) {
 341                         return true; // this means "use the default"
 342                 }
 343
 344                 return in_array( $format, $this->mSupportedFormats );
 345         }
 346
 347         /**
 348          * Throws an MWException if isSupportedFormat( $format ) is not true. Convenient
 349          * for checking whether a format provided as a parameter is actually supported.
 350          *
 351          * @param String $format the serialization format to check
 352          */
 353         protected function checkFormat( $format ) {
 354                 if ( !$this->isSupportedFormat( $format ) ) {
 355                         throw new MWException( "Format $format is not supported for content model " . $this->getModelName() );
 356                 }
 357         }
 358
 359         /**
 360          * Returns overrides for action handlers.
 361          * Classes listed here will be used instead of the default one when
 362          * (and only when) $wgActions[$action] === true. This allows subclasses
 363          * to override the default action handlers.
 364          *
 365          * @return Array
 366          */
 367         public function getActionOverrides() {
 368                 return array();
 369         }
 370
 371         /**
 372          * Return an Article object suitable for viewing the given object
 373          *
 374          * NOTE: does *not* do special handling for Image and Category pages!
 375          *       Use Article::newFromTitle() for that!
 376          *
 377          * @param Title $title
 378          * @return Article
 379          * @todo Article is being refactored into an action class, keep track of that
 380          * @todo Article really defines the view of the content... rename this method to createViewPage ?
 381          */
 382         public function createArticle( Title $title ) {
 383                 $this->checkModelName( $title->getContentModelName() );
 384
 385                 $article = new Article($title);
 386                 return $article;
 387         }
 388
 389         /**
 390          * Return an EditPage object suitable for editing the given object
 391          *
 392          * @param Article $article
 393          * @return EditPage
 394          */
 395         public function createEditPage( Article $article ) {
 396                 $this->checkModelName( $article->getContentModelName() );
 397
 398                 $editPage = new EditPage( $article );
 399                 return $editPage;
 400         }
 401
 402         /**
 403          * Return an ExternalEdit object suitable for editing the given object
 404          *
 405          * @param IContextSource $context
 406          * @return ExternalEdit
 407          * @todo does anyone or anythign actually use the external edit facility? Can we just deprecate and ignore it?
 408          */
 409         public function createExternalEdit( IContextSource $context ) {
 410                 $this->checkModelName( $context->getTitle()->getContentModelName() );
 411
 412                 $externalEdit = new ExternalEdit( $context );
 413                 return $externalEdit;
 414         }
 415
 416         /**
 417          * Factory
 418          * @param $context IContextSource context to use, anything else will be ignored
 419          * @param $old Integer old ID we want to show and diff with.
 420          * @param $new String either 'prev' or 'next'.
 421          * @param $rcid Integer ??? FIXME (default 0)
 422          * @param $refreshCache boolean If set, refreshes the diff cache
 423          * @param $unhide boolean If set, allow viewing deleted revs
 424          *
 425          * @return DifferenceEngine
 426          */
 427         public function createDifferenceEngine( IContextSource $context, $old = 0, $new = 0, $rcid = 0, #FIMXE: use everywhere!
 428                                                                                  $refreshCache = false, $unhide = false ) {
 429
 430                 $this->checkModelName( $context->getTitle()->getContentModelName() );
 431
 432                 $diffEngineClass = $this->getDiffEngineClass();
 433
 434                 return new $diffEngineClass( $context, $old, $new, $rcid, $refreshCache, $unhide );
 435         }
 436
 437         /**
 438          * Returns the name of the diff engine to use.
 439          *
 440          * @since 0.1
 441          *
 442          * @return string
 443          */
 444         protected function getDiffEngineClass() {
 445                 return 'DifferenceEngine';
 446         }
 447
 448         /**
 449          * attempts to merge differences between three versions.
 450          * Returns a new Content object for a clean merge and false for failure or a conflict.
 451          *
 452          * This default implementation always returns false.
 453          *
 454          * @param $oldContent String
 455          * @param $myContent String
 456          * @param $yourContent String
 457          * @return Content|Bool
 458          */
 459         public function merge3( Content $oldContent, Content $myContent, Content $yourContent ) {
 460                 return false;
 461         }
 462
 463         /**
 464          * Return an applicable autosummary if one exists for the given edit.
 465          *
 466          * @param $oldContent Content|null: the previous text of the page.
 467          * @param $newContent Content|null: The submitted text of the page.
 468          * @param $flags Int bitmask: a bitmask of flags submitted for the edit.
 469          *
 470          * @return string An appropriate autosummary, or an empty string.
 471          */
 472         public function getAutosummary( Content $oldContent = null, Content $newContent = null, $flags ) {
 473                 global $wgContLang;
 474
 475                 // Decide what kind of autosummary is needed.
 476
 477                 // Redirect autosummaries
 478
 479                 /**
 480                  * @var $ot Title
 481                  * @var $rt Title
 482                  */
 483
 484                 $ot = !is_null( $oldContent ) ? $oldContent->getRedirectTarget() : null;
 485                 $rt = !is_null( $newContent ) ? $newContent->getRedirectTarget() : null;
 486
 487                 if ( is_object( $rt ) && ( !is_object( $ot ) || !$rt->equals( $ot ) || $ot->getFragment() != $rt->getFragment() ) ) {
 488
 489                         $truncatedtext = $newContent->getTextForSummary(
 490                                 250
 491                                         - strlen( wfMsgForContent( 'autoredircomment' ) )
 492                                         - strlen( $rt->getFullText() ) );
 493
 494                         return wfMsgForContent( 'autoredircomment', $rt->getFullText(), $truncatedtext );
 495                 }
 496
 497                 // New page autosummaries
 498                 if ( $flags & EDIT_NEW && $newContent->getSize() > 0 ) {
 499                         // If they're making a new article, give its text, truncated, in the summary.
 500
 501                         $truncatedtext = $newContent->getTextForSummary(
 502                                 200 - strlen( wfMsgForContent( 'autosumm-new' ) ) );
 503
 504                         return wfMsgForContent( 'autosumm-new', $truncatedtext );
 505                 }
 506
 507                 // Blanking autosummaries
 508                 if ( !empty( $oldContent ) && $oldContent->getSize() > 0 && $newContent->getSize() == 0 ) {
 509                         return wfMsgForContent( 'autosumm-blank' );
 510                 } elseif ( !empty( $oldContent ) && $oldContent->getSize() > 10 * $newContent->getSize() && $newContent->getSize() < 500 ) {
 511                         // Removing more than 90% of the article
 512
 513                         $truncatedtext = $newContent->getTextForSummary(
 514                                 200 - strlen( wfMsgForContent( 'autosumm-replace' ) ) );
 515
 516                         return wfMsgForContent( 'autosumm-replace', $truncatedtext );
 517                 }
 518
 519                 // If we reach this point, there's no applicable autosummary for our case, so our
 520                 // autosummary is empty.
 521
 522                 return '';
 523         }
 524
 525         /**
 526          * Auto-generates a deletion reason
 527          *
 528          * @param $title Title: the page's title
 529          * @param &$hasHistory Boolean: whether the page has a history
 530          * @return mixed String containing deletion reason or empty string, or boolean false
 531          *    if no revision occurred
 532          *
 533          * @XXX &$hasHistory is extremely ugly, it's here because WikiPage::getAutoDeleteReason() and Article::getReason() have it / want it.
 534          */
 535         public function getAutoDeleteReason( Title $title, &$hasHistory ) {
 536                 $dbw = wfGetDB( DB_MASTER );
 537
 538                 // Get the last revision
 539                 $rev = Revision::newFromTitle( $title );
 540
 541                 if ( is_null( $rev ) ) {
 542                         return false;
 543                 }
 544
 545                 // Get the article's contents
 546                 $content = $rev->getContent();
 547                 $blank = false;
 548
 549                 // If the page is blank, use the text from the previous revision,
 550                 // which can only be blank if there's a move/import/protect dummy revision involved
 551                 if ( $content->getSize() == 0 ) {
 552                         $prev = $rev->getPrevious();
 553
 554                         if ( $prev )    {
 555                                 $content = $rev->getContent();
 556                                 $blank = true;
 557                         }
 558                 }
 559
 560                 // Find out if there was only one contributor
 561                 // Only scan the last 20 revisions
 562                 $res = $dbw->select( 'revision', 'rev_user_text',
 563                         array( 'rev_page' => $title->getArticleID(), $dbw->bitAnd( 'rev_deleted', Revision::DELETED_USER ) . ' = 0' ),
 564                         __METHOD__,
 565                         array( 'LIMIT' => 20 )
 566                 );
 567
 568                 if ( $res === false ) {
 569                         // This page has no revisions, which is very weird
 570                         return false;
 571                 }
 572
 573                 $hasHistory = ( $res->numRows() > 1 );
 574                 $row = $dbw->fetchObject( $res );
 575
 576                 if ( $row ) { // $row is false if the only contributor is hidden
 577                         $onlyAuthor = $row->rev_user_text;
 578                         // Try to find a second contributor
 579                         foreach ( $res as $row ) {
 580                                 if ( $row->rev_user_text != $onlyAuthor ) { // Bug 22999
 581                                         $onlyAuthor = false;
 582                                         break;
 583                                 }
 584                         }
 585                 } else {
 586                         $onlyAuthor = false;
 587                 }
 588
 589                 // Generate the summary with a '$1' placeholder
 590                 if ( $blank ) {
 591                         // The current revision is blank and the one before is also
 592                         // blank. It's just not our lucky day
 593                         $reason = wfMsgForContent( 'exbeforeblank', '$1' );
 594                 } else {
 595                         if ( $onlyAuthor ) {
 596                                 $reason = wfMsgForContent( 'excontentauthor', '$1', $onlyAuthor );
 597                         } else {
 598                                 $reason = wfMsgForContent( 'excontent', '$1' );
 599                         }
 600                 }
 601
 602                 if ( $reason == '-' ) {
 603                         // Allow these UI messages to be blanked out cleanly
 604                         return '';
 605                 }
 606
 607                 // Max content length = max comment length - length of the comment (excl. $1)
 608                 $text = $content->getTextForSummary( 255 - ( strlen( $reason ) - 2 ) );
 609
 610                 // Now replace the '$1' placeholder
 611                 $reason = str_replace( '$1', $text, $reason );
 612
 613                 return $reason;
 614         }
 615
 616         #@TODO: getSecondaryUpdatesForDeletion( Content ) returns an array of SecondaryDataUpdate objects
 617         #... or do that in the Content class?
 618
 619         /**
 620          * Get the Content object that needs to be saved in order to undo all revisions
 621          * between $undo and $undoafter. Revisions must belong to the same page,
 622          * must exist and must not be deleted
 623          * @param $current Revision the current text
 624          * @param $undo Revision the revision to undo
 625          * @param $undoafter Revision Must be an earlier revision than $undo
 626          * @return mixed string on success, false on failure
 627          */
 628         public function getUndoContent( Revision $current, Revision $undo, Revision $undoafter ) {
 629                 $cur_content = $current->getContent();
 630
 631                 if ( empty( $cur_content ) ) {
 632                         return false; // no page
 633                 }
 634
 635                 $undo_content = $undo->getContent();
 636                 $undoafter_content = $undoafter->getContent();
 637
 638                 if ( $cur_content->equals( $undo_content ) ) {
 639                         // No use doing a merge if it's just a straight revert.
 640                         return $undoafter_content;
 641                 }
 642
 643                 $undone_content = $this->merge3( $undo_content, $undoafter_content, $cur_content );
 644
 645                 return $undone_content;
 646         }
 647
 648         /**
 649          * Returns true for content models that support caching using the ParserCache mechanism.
 650          * See WikiPage::isParserCacheUser().
 651          *
 652          * @return bool
 653          */
 654         public function isParserCacheSupported() {
 655                 return true;
 656         }
 657 }
 658
 659
 660 abstract class TextContentHandler extends ContentHandler {
 661
 662         public function __construct( $modelName, $formats ) {
 663                 parent::__construct( $modelName, $formats );
 664         }
 665
 666         public function serializeContent( Content $content, $format = null ) {
 667                 $this->checkFormat( $format );
 668                 return $content->getNativeData();
 669         }
 670
 671         /**
 672          * attempts to merge differences between three versions.
 673          * Returns a new Content object for a clean merge and false for failure or a conflict.
 674          *
 675          * All three Content objects passed as parameters must have the same content model.
 676          *
 677          * This text-based implementation uses wfMerge().
 678          *
 679          * @param $oldContent String
 680          * @param $myContent String
 681          * @param $yourContent String
 682          * @return Content|Bool
 683          */
 684         public function merge3( Content $oldContent, Content $myContent, Content $yourContent ) {
 685                 $this->checkModelName( $oldContent->getModelName() );
 686                 $this->checkModelName( $myContent->getModelName() );
 687                 $this->checkModelName( $yourContent->getModelName() );
 688
 689                 $format = $this->getDefaultFormat();
 690
 691                 $old = $this->serializeContent( $oldContent, $format );
 692                 $mine = $this->serializeContent( $myContent, $format );
 693                 $yours = $this->serializeContent( $yourContent, $format );
 694
 695                 $ok = wfMerge( $old, $mine, $yours, $result );
 696
 697                 if ( !$ok ) {
 698                         return false;
 699                 }
 700
 701                 if ( !$result ) {
 702                         return $this->makeEmptyContent();
 703                 }
 704
 705                 $mergedContent = $this->unserializeContent( $result, $format );
 706                 return $mergedContent;
 707         }
 708
 709
 710 }
 711 class WikitextContentHandler extends TextContentHandler {
 712
 713         public function __construct( $modelName = CONTENT_MODEL_WIKITEXT ) {
 714                 parent::__construct( $modelName, array( 'application/x-wiki' ) );
 715         }
 716
 717         public function unserializeContent( $text, $format = null ) {
 718                 $this->checkFormat( $format );
 719
 720                 return new WikitextContent( $text );
 721         }
 722
 723         public function makeEmptyContent() {
 724                 return new WikitextContent( '' );
 725         }
 726
 727
 728 }
 729
 730 #XXX: make ScriptContentHandler base class with plugin interface for syntax highlighting?
 731
 732 class JavaScriptContentHandler extends TextContentHandler {
 733
 734         public function __construct( $modelName = CONTENT_MODEL_WIKITEXT ) {
 735                 parent::__construct( $modelName, array( 'text/javascript' ) ); #XXX: or use $wgJsMimeType? this is for internal storage, not HTTP...
 736         }
 737
 738         public function unserializeContent( $text, $format = null ) {
 739                 $this->checkFormat( $format );
 740
 741                 return new JavaScriptContent( $text );
 742         }
 743
 744         public function makeEmptyContent() {
 745                 return new JavaScriptContent( '' );
 746         }
 747 }
 748
 749 class CssContentHandler extends TextContentHandler {
 750
 751         public function __construct( $modelName = CONTENT_MODEL_WIKITEXT ) {
 752                 parent::__construct( $modelName, array( 'text/css' ) );
 753         }
 754
 755         public function unserializeContent( $text, $format = null ) {
 756                 $this->checkFormat( $format );
 757
 758                 return new CssContent( $text );
 759         }
 760
 761         public function makeEmptyContent() {
 762                 return new CssContent( '' );
 763         }
 764
 765 }