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  * @since 1.WD
  24  */
  25 abstract class ContentHandler {
  26
  27         /**
  28          * Conveniance function for getting flat text from a Content object. This should only
  29          * be used in the context of backwards compatibility with code that is not yet able
  30          * to handle Content objects!
  31          *
  32          * If $content is null, this method returns the empty string.
  33          *
  34          * If $content is an instance of TextContent, this method returns the flat text as returned by $content->getNativeData().
  35          *
  36          * If $content is not a TextContent object, the bahaviour of this method depends on the global $wgContentHandlerTextFallback:
  37          * * If $wgContentHandlerTextFallback is 'fail' and $content is not a TextContent object, an MWException is thrown.
  38          * * If $wgContentHandlerTextFallback is 'serialize' and $content is not a TextContent object, $content->serialize()
  39          * is called to get a string form of the content.
  40          * * If $wgContentHandlerTextFallback is 'ignore' and $content is not a TextContent object, this method returns null.
  41          * * otherwise, the behaviour is undefined.
  42          *
  43          * @static
  44          * @param Content|null $content
  45          * @return null|string the textual form of $content, if available
  46          * @throws MWException if $content is not an instance of TextContent and $wgContentHandlerTextFallback was set to 'fail'.
  47          */
  48         public static function getContentText( Content $content = null ) {
  49                 global $wgContentHandlerTextFallback;
  50
  51                 if ( is_null( $content ) ) {
  52                         return '';
  53                 }
  54
  55                 if ( $content instanceof TextContent ) {
  56                         return $content->getNativeData();
  57                 }
  58
  59                 if ( $wgContentHandlerTextFallback == 'fail' ) {
  60                         throw new MWException( "Attempt to get text from Content with model " . $content->getModel() );
  61                 }
  62
  63                 if ( $wgContentHandlerTextFallback == 'serialize' ) {
  64                         return $content->serialize();
  65                 }
  66
  67                 return null;
  68         }
  69
  70         /**
  71          * Conveniance function for creating a Content object from a given textual representation.
  72          *
  73          * $text will be deserialized into a Content object of the model specified by $modelId (or,
  74          * if that is not given, $title->getContentModel()) using the given format.
  75          *
  76          * @static
  77          * @param string $text the textual represenation, will be unserialized to create the Content object
  78          * @param Title $title the title of the page this text belongs to, required as a context for deserialization
  79          * @param null|String $modelId the model to deserialize to. If not provided, $title->getContentModel() is used.
  80          * @param null|String $format the format to use for deserialization. If not given, the model's default format is used.
  81          *
  82          * @return Content a Content object representing $text
  83          * @throw MWException if $model or $format is not supported or if $text can not be unserialized using $format.
  84          */
  85         public static function makeContent( $text, Title $title, $modelId = null, $format = null ) {
  86
  87                 if ( is_null( $modelId ) ) {
  88                         $modelId = $title->getContentModel();
  89                 }
  90
  91                 $handler = ContentHandler::getForModelID( $modelId );
  92                 return $handler->unserializeContent( $text, $format );
  93         }
  94
  95         /**
  96          * Returns the name of the default content model to be used for the page with the given title.
  97          *
  98          * Note: There should rarely be need to call this method directly.
  99          * To determine the actual content model for a given page, use Title::getContentModel().
 100          *
 101          * Which model is to be used per default for the page is determined based on several factors:
 102          * * The global setting $wgNamespaceContentModels specifies a content model per namespace.
 103          * * The hook DefaultModelFor may be used to override the page's default model.
 104          * * Pages in NS_MEDIAWIKI and NS_USER default to the CSS or JavaScript model if they end in .js or .css, respectively.
 105          * * Pages in NS_MEDIAWIKI default to the wikitext model otherwise.
 106          * * 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.
 107          * * The hook TitleIsWikitextPage may be used to force a page to use the wikitext model.
 108          *
 109          * If none of the above applies, the wikitext model is used.
 110          *
 111          * Note: this is used by, and may thus not use, Title::getContentModel()
 112          *
 113          * @static
 114          * @param Title $title
 115          * @return null|string default model name for the page given by $title
 116          */
 117         public static function getDefaultModelFor( Title $title ) {
 118                 global $wgNamespaceContentModels;
 119
 120                 // NOTE: this method must not rely on $title->getContentModel() directly or indirectly,
 121                 //       because it is used to initialized the mContentModel memebr.
 122
 123                 $ns = $title->getNamespace();
 124
 125                 $ext = false;
 126                 $m = null;
 127                 $model = null;
 128
 129                 if ( !empty( $wgNamespaceContentModels[ $ns ] ) ) {
 130                         $model = $wgNamespaceContentModels[ $ns ];
 131                 }
 132
 133                 // hook can determin default model
 134                 if ( !wfRunHooks( 'ContentHandlerDefaultModelFor', array( $title, &$model ) ) ) {
 135                         if ( !is_null( $model ) ) {
 136                                 return $model;
 137                         }
 138                 }
 139
 140                 // Could this page contain custom CSS or JavaScript, based on the title?
 141                 $isCssOrJsPage = NS_MEDIAWIKI == $ns && preg_match( '!\.(css|js)$!u', $title->getText(), $m );
 142                 if ( $isCssOrJsPage ) {
 143                         $ext = $m[1];
 144                 }
 145
 146                 // hook can force js/css
 147                 wfRunHooks( 'TitleIsCssOrJsPage', array( $title, &$isCssOrJsPage ) );
 148
 149                 // Is this a .css subpage of a user page?
 150                 $isJsCssSubpage = NS_USER == $ns && !$isCssOrJsPage && preg_match( "/\\/.*\\.(js|css)$/", $title->getText(), $m );
 151                 if ( $isJsCssSubpage ) {
 152                         $ext = $m[1];
 153                 }
 154
 155                 // is this wikitext, according to $wgNamespaceContentModels or the DefaultModelFor hook?
 156                 $isWikitext = is_null( $model ) || $model == CONTENT_MODEL_WIKITEXT;
 157                 $isWikitext = $isWikitext && !$isCssOrJsPage && !$isJsCssSubpage;
 158
 159                 // hook can override $isWikitext
 160                 wfRunHooks( 'TitleIsWikitextPage', array( $title, &$isWikitext ) );
 161
 162                 if ( !$isWikitext ) {
 163                         switch ( $ext ) {
 164                                 case 'js':
 165                                         return CONTENT_MODEL_JAVASCRIPT;
 166                                 case 'css':
 167                                         return CONTENT_MODEL_CSS;
 168                                 default:
 169                                         return is_null( $model ) ? CONTENT_MODEL_TEXT : $model;
 170                         }
 171                 }
 172
 173                 // we established that is must be wikitext
 174
 175                 return CONTENT_MODEL_WIKITEXT;
 176         }
 177
 178         /**
 179          * returns the appropriate ContentHandler singleton for the given title
 180          *
 181          * @static
 182          * @param Title $title
 183          * @return ContentHandler
 184          */
 185         public static function getForTitle( Title $title ) {
 186                 $modelId = $title->getContentModel();
 187                 return ContentHandler::getForModelID( $modelId );
 188         }
 189
 190         /**
 191          * returns the appropriate ContentHandler singleton for the given Content object
 192          *
 193          * @static
 194          * @param Content $content
 195          * @return ContentHandler
 196          */
 197         public static function getForContent( Content $content ) {
 198                 $modelId = $content->getModel();
 199                 return ContentHandler::getForModelID( $modelId );
 200         }
 201
 202         /**
 203          * returns the ContentHandler singleton for the given model id. Use the CONTENT_MODEL_XXX constants to
 204          * identify the desired content model.
 205          *
 206          * ContentHandler singletons are take from the global $wgContentHandlers array. Keys in that array are
 207          * model names, the values are either ContentHandler singleton objects, or strings specifying the appropriate
 208          * subclass of ContentHandler.
 209          *
 210          * If a class name in encountered when looking up the singleton for a given model name, the class is
 211          * instantiated and the class name is replaced by te resulting singleton in $wgContentHandlers.
 212          *
 213          * If no ContentHandler is defined for the desired $modelId, the ContentHandler may be provided by the
 214          * a ContentHandlerForModelID hook. if no Contenthandler can be determined, an MWException is raised.
 215          *
 216          * @static
 217          * @param $modelId int the id of the content model for which to get a handler. Use CONTENT_MODEL_XXX constants.
 218          * @return ContentHandler the ContentHandler singleton for handling the model given by $modelId
 219          * @throws MWException if no handler is known for $modelId.
 220          */
 221         public static function getForModelID( $modelId ) {
 222                 global $wgContentHandlers;
 223
 224                 if ( empty( $wgContentHandlers[$modelId] ) ) {
 225                         $handler = null;
 226
 227                         wfRunHooks( 'ContentHandlerForModelID', array( $modelId, &$handler ) );
 228
 229                         if ( $handler ) { // NOTE: may be a string or an object, either is fine!
 230                                 $wgContentHandlers[$modelId] = $handler;
 231                         } else {
 232                                 throw new MWException( "No handler for model #$modelId registered in \$wgContentHandlers" );
 233                         }
 234                 }
 235
 236                 if ( is_string( $wgContentHandlers[$modelId] ) ) {
 237                         $class = $wgContentHandlers[$modelId];
 238                         $wgContentHandlers[$modelId] = new $class( $modelId );
 239                 }
 240
 241                 return $wgContentHandlers[$modelId];
 242         }
 243
 244         /**
 245          * Returns the appropriate mime type for a given content format,
 246          * or null if no mime type is known for this format.
 247          *
 248          * Mime types can be registered in the global array $wgContentFormatMimeTypes.
 249          *
 250          * @static
 251          * @param int $id the content format id, as given by a CONTENT_FORMAT_XXX constant
 252          *        or returned by Revision::getContentFormat().
 253          *
 254          * @return String|null the content format's mime type.
 255          */
 256         public static function getContentFormatMimeType( $id ) {
 257                 global $wgContentFormatMimeTypes;
 258
 259                 if ( !isset( $wgContentFormatMimeTypes[ $id ] ) ) {
 260                         return null;
 261                 }
 262
 263                 return $wgContentFormatMimeTypes[ $id ];
 264         }
 265
 266         /**
 267          * Returns the content format if for a given mime type,
 268          * or null if no format id if known for this mime type.
 269          *
 270          * Mime types can be registered in the global array $wgContentFormatMimeTypes.
 271          *
 272          * @static
 273          * @param String $mime the mime type
 274          *
 275          * @return int|null the format id, as defined by a CONTENT_FORMAT_XXX constant
 276          */
 277         public static function getContentFormatID( $mime ) {
 278                 global $wgContentFormatMimeTypes;
 279
 280                 static $format_ids = null;
 281
 282                 if ( $format_ids === null ) {
 283                         $format_ids = array_flip( $wgContentFormatMimeTypes );
 284                 }
 285
 286                 if ( !isset( $format_ids[ $mime ] ) ) {
 287                         return null;
 288                 }
 289
 290                 return $format_ids[ $mime ];
 291         }
 292
 293         /**
 294          * Returns the localized name for a given content model,
 295          * or null of no mime type is known.
 296          *
 297          * Model names are localized using system messages. Message keys
 298          * have the form conent-model-$id.
 299          *
 300          * @static
 301          * @param int $id the content model id, as given by a CONTENT_MODEL_XXX constant
 302          *        or returned by Revision::getContentModel().
 303          *
 304          * @return String|null the content format's mime type.
 305          */
 306         public static function getContentModelName( $id ) {
 307                 $key = "content-model-$id";
 308
 309                 if ( wfEmptyMsg( $key ) ) return null;
 310                 else return wfMsg( $key );
 311         }
 312
 313         // ----------------------------------------------------------------------------------------------------------
 314
 315         protected $mModelID;
 316         protected $mSupportedFormats;
 317
 318         /**
 319          * Constructor, initializing the ContentHandler instance with it's model id and a list of supported formats.
 320          * Values for the parameters are typically provided as literals by subclasses' constructors.
 321          *
 322          * @param int $modelId (use CONTENT_MODEL_XXX constants).
 323          * @param array $formats list for supported serialization formats (typically as MIME types)
 324          */
 325         public function __construct( $modelId, $formats ) {
 326                 $this->mModelID = $modelId;
 327                 $this->mSupportedFormats = $formats;
 328         }
 329
 330
 331         /**
 332          * Serializes Content object of the type supported by this ContentHandler.
 333          *
 334          * @abstract
 335          * @param Content $content the Content object to serialize
 336          * @param null $format the desired serialization format
 337          * @return String serialized form of the content
 338          */
 339         public abstract function serializeContent( Content $content, $format = null );
 340
 341         /**
 342          * Unserializes a Content object of the type supported by this ContentHandler.
 343          *
 344          * @abstract
 345          * @param $blob String serialized form of the content
 346          * @param null $format the format used for serialization
 347          * @return Content the Content object created by deserializing $blob
 348          */
 349         public abstract function unserializeContent( $blob, $format = null );
 350
 351         /**
 352          * Creates an empty Content object of the type supported by this ContentHandler.
 353          *
 354          * @return Content
 355          */
 356         public abstract function makeEmptyContent();
 357
 358         /**
 359          * Returns the model id that identifies the content model this ContentHandler can handle.
 360          * Use with the CONTENT_MODEL_XXX constants.
 361          *
 362          * @return int the model id
 363          */
 364         public function getModelID() {
 365                 return $this->mModelID;
 366         }
 367
 368         /**
 369          * Throws an MWException if $model_id is not the id of the content model
 370          * supported by this ContentHandler.
 371          *
 372          * @param int $model_id the model to check
 373          */
 374         protected function checkModelID( $model_id ) {
 375                 if ( $model_id !== $this->mModelID ) {
 376                         $model_name = ContentHandler::getContentModelName( $model_id );
 377                         $own_model_name = ContentHandler::getContentModelName( $this->mModelID );
 378
 379                         throw new MWException( "Bad content model: expected {$this->mModelID} ($own_model_name) but got found $model_id ($model_name)." );
 380                 }
 381         }
 382
 383         /**
 384          * Returns a list of serialization formats supported by the serializeContent() and unserializeContent() methods of
 385          * this ContentHandler.
 386          *
 387          * @return array of serialization formats as MIME type like strings
 388          */
 389         public function getSupportedFormats() {
 390                 return $this->mSupportedFormats;
 391         }
 392
 393         /**
 394          * The format used for serialization/deserialization per default by this ContentHandler.
 395          *
 396          * This default implementation will return the first element of the array of formats
 397          * that was passed to the constructor.
 398          *
 399          * @return String the name of the default serialiozation format as a MIME type
 400          */
 401         public function getDefaultFormat() {
 402                 return $this->mSupportedFormats[0];
 403         }
 404
 405         /**
 406          * Returns true if $format is a serialization format supported by this ContentHandler,
 407          * and false otherwise.
 408          *
 409          * Note that if $format is null, this method always returns true, because null
 410          * means "use the default format".
 411          *
 412          * @param String $format the serialization format to check
 413          * @return bool
 414          */
 415         public function isSupportedFormat( $format ) {
 416
 417                 if ( !$format ) {
 418                         return true; // this means "use the default"
 419                 }
 420
 421                 return in_array( $format, $this->mSupportedFormats );
 422         }
 423
 424         /**
 425          * Throws an MWException if isSupportedFormat( $format ) is not true. Convenient
 426          * for checking whether a format provided as a parameter is actually supported.
 427          *
 428          * @param String $format the serialization format to check
 429          */
 430         protected function checkFormat( $format ) {
 431                 if ( !$this->isSupportedFormat( $format ) ) {
 432                         throw new MWException( "Format $format is not supported for content model " . $this->getModelID() );
 433                 }
 434         }
 435
 436         /**
 437          * Returns overrides for action handlers.
 438          * Classes listed here will be used instead of the default one when
 439          * (and only when) $wgActions[$action] === true. This allows subclasses
 440          * to override the default action handlers.
 441          *
 442          * @return Array
 443          */
 444         public function getActionOverrides() {
 445                 return array();
 446         }
 447
 448         /**
 449          * Return an Article object suitable for viewing the given object
 450          *
 451          * NOTE: does *not* do special handling for Image and Category pages!
 452          *       Use Article::newFromTitle() for that!
 453          *
 454          * @param Title $title
 455          * @return Article
 456          * @todo Article is being refactored into an action class, keep track of that
 457          * @todo Article really defines the view of the content... rename this method to createViewPage ?
 458          */
 459         public function createArticle( Title $title ) {
 460                 $this->checkModelID( $title->getContentModel() );
 461
 462                 $article = new Article($title);
 463                 return $article;
 464         }
 465
 466         /**
 467          * Return an EditPage object suitable for editing the given object
 468          *
 469          * @param Article $article
 470          * @return EditPage
 471          */
 472         public function createEditPage( Article $article ) {
 473                 $this->checkModelID( $article->getPage()->getContentModel() );
 474
 475                 $editPage = new EditPage( $article );
 476                 return $editPage;
 477         }
 478
 479         /**
 480          * Return an ExternalEdit object suitable for editing the given object
 481          *
 482          * @param IContextSource $context
 483          * @return ExternalEdit
 484          * @todo does anyone or anythign actually use the external edit facility? Can we just deprecate and ignore it?
 485          */
 486         public function createExternalEdit( IContextSource $context ) {
 487                 $this->checkModelID( $context->getTitle()->getContentModel() );
 488
 489                 $externalEdit = new ExternalEdit( $context );
 490                 return $externalEdit;
 491         }
 492
 493         /**
 494          * Factory
 495          * @param $context IContextSource context to use, anything else will be ignored
 496          * @param $old Integer old ID we want to show and diff with.
 497          * @param $new String either 'prev' or 'next'.
 498          * @param $rcid Integer ??? FIXME (default 0)
 499          * @param $refreshCache boolean If set, refreshes the diff cache
 500          * @param $unhide boolean If set, allow viewing deleted revs
 501          *
 502          * @return DifferenceEngine
 503          */
 504         public function createDifferenceEngine( IContextSource $context, $old = 0, $new = 0, $rcid = 0, #FIMXE: use everywhere!
 505                                                                                  $refreshCache = false, $unhide = false ) {
 506
 507                 $this->checkModelID( $context->getTitle()->getContentModel() );
 508
 509                 $diffEngineClass = $this->getDiffEngineClass();
 510
 511                 return new $diffEngineClass( $context, $old, $new, $rcid, $refreshCache, $unhide );
 512         }
 513
 514         /**
 515          * Returns the name of the diff engine to use.
 516          *
 517          * @since 0.1
 518          *
 519          * @return string
 520          */
 521         protected function getDiffEngineClass() {
 522                 return 'DifferenceEngine';
 523         }
 524
 525         /**
 526          * attempts to merge differences between three versions.
 527          * Returns a new Content object for a clean merge and false for failure or a conflict.
 528          *
 529          * This default implementation always returns false.
 530          *
 531          * @param $oldContent String
 532          * @param $myContent String
 533          * @param $yourContent String
 534          * @return Content|Bool
 535          */
 536         public function merge3( Content $oldContent, Content $myContent, Content $yourContent ) {
 537                 return false;
 538         }
 539
 540         /**
 541          * Return an applicable autosummary if one exists for the given edit.
 542          *
 543          * @param $oldContent Content|null: the previous text of the page.
 544          * @param $newContent Content|null: The submitted text of the page.
 545          * @param $flags Int bitmask: a bitmask of flags submitted for the edit.
 546          *
 547          * @return string An appropriate autosummary, or an empty string.
 548          */
 549         public function getAutosummary( Content $oldContent = null, Content $newContent = null, $flags ) {
 550                 global $wgContLang;
 551
 552                 // Decide what kind of autosummary is needed.
 553
 554                 // Redirect autosummaries
 555
 556                 /**
 557                  * @var $ot Title
 558                  * @var $rt Title
 559                  */
 560
 561                 $ot = !is_null( $oldContent ) ? $oldContent->getRedirectTarget() : null;
 562                 $rt = !is_null( $newContent ) ? $newContent->getRedirectTarget() : null;
 563
 564                 if ( is_object( $rt ) && ( !is_object( $ot ) || !$rt->equals( $ot ) || $ot->getFragment() != $rt->getFragment() ) ) {
 565
 566                         $truncatedtext = $newContent->getTextForSummary(
 567                                 250
 568                                         - strlen( wfMsgForContent( 'autoredircomment' ) )
 569                                         - strlen( $rt->getFullText() ) );
 570
 571                         return wfMsgForContent( 'autoredircomment', $rt->getFullText(), $truncatedtext );
 572                 }
 573
 574                 // New page autosummaries
 575                 if ( $flags & EDIT_NEW && $newContent->getSize() > 0 ) {
 576                         // If they're making a new article, give its text, truncated, in the summary.
 577
 578                         $truncatedtext = $newContent->getTextForSummary(
 579                                 200 - strlen( wfMsgForContent( 'autosumm-new' ) ) );
 580
 581                         return wfMsgForContent( 'autosumm-new', $truncatedtext );
 582                 }
 583
 584                 // Blanking autosummaries
 585                 if ( !empty( $oldContent ) && $oldContent->getSize() > 0 && $newContent->getSize() == 0 ) {
 586                         return wfMsgForContent( 'autosumm-blank' );
 587                 } elseif ( !empty( $oldContent ) && $oldContent->getSize() > 10 * $newContent->getSize() && $newContent->getSize() < 500 ) {
 588                         // Removing more than 90% of the article
 589
 590                         $truncatedtext = $newContent->getTextForSummary(
 591                                 200 - strlen( wfMsgForContent( 'autosumm-replace' ) ) );
 592
 593                         return wfMsgForContent( 'autosumm-replace', $truncatedtext );
 594                 }
 595
 596                 // If we reach this point, there's no applicable autosummary for our case, so our
 597                 // autosummary is empty.
 598
 599                 return '';
 600         }
 601
 602         /**
 603          * Auto-generates a deletion reason
 604          *
 605          * @param $title Title: the page's title
 606          * @param &$hasHistory Boolean: whether the page has a history
 607          * @return mixed String containing deletion reason or empty string, or boolean false
 608          *    if no revision occurred
 609          *
 610          * @XXX &$hasHistory is extremely ugly, it's here because WikiPage::getAutoDeleteReason() and Article::getReason() have it / want it.
 611          */
 612         public function getAutoDeleteReason( Title $title, &$hasHistory ) {
 613                 $dbw = wfGetDB( DB_MASTER );
 614
 615                 // Get the last revision
 616                 $rev = Revision::newFromTitle( $title );
 617
 618                 if ( is_null( $rev ) ) {
 619                         return false;
 620                 }
 621
 622                 // Get the article's contents
 623                 $content = $rev->getContent();
 624                 $blank = false;
 625
 626                 // If the page is blank, use the text from the previous revision,
 627                 // which can only be blank if there's a move/import/protect dummy revision involved
 628                 if ( $content->getSize() == 0 ) {
 629                         $prev = $rev->getPrevious();
 630
 631                         if ( $prev )    {
 632                                 $content = $rev->getContent();
 633                                 $blank = true;
 634                         }
 635                 }
 636
 637                 // Find out if there was only one contributor
 638                 // Only scan the last 20 revisions
 639                 $res = $dbw->select( 'revision', 'rev_user_text',
 640                         array( 'rev_page' => $title->getArticleID(), $dbw->bitAnd( 'rev_deleted', Revision::DELETED_USER ) . ' = 0' ),
 641                         __METHOD__,
 642                         array( 'LIMIT' => 20 )
 643                 );
 644
 645                 if ( $res === false ) {
 646                         // This page has no revisions, which is very weird
 647                         return false;
 648                 }
 649
 650                 $hasHistory = ( $res->numRows() > 1 );
 651                 $row = $dbw->fetchObject( $res );
 652
 653                 if ( $row ) { // $row is false if the only contributor is hidden
 654                         $onlyAuthor = $row->rev_user_text;
 655                         // Try to find a second contributor
 656                         foreach ( $res as $row ) {
 657                                 if ( $row->rev_user_text != $onlyAuthor ) { // Bug 22999
 658                                         $onlyAuthor = false;
 659                                         break;
 660                                 }
 661                         }
 662                 } else {
 663                         $onlyAuthor = false;
 664                 }
 665
 666                 // Generate the summary with a '$1' placeholder
 667                 if ( $blank ) {
 668                         // The current revision is blank and the one before is also
 669                         // blank. It's just not our lucky day
 670                         $reason = wfMsgForContent( 'exbeforeblank', '$1' );
 671                 } else {
 672                         if ( $onlyAuthor ) {
 673                                 $reason = wfMsgForContent( 'excontentauthor', '$1', $onlyAuthor );
 674                         } else {
 675                                 $reason = wfMsgForContent( 'excontent', '$1' );
 676                         }
 677                 }
 678
 679                 if ( $reason == '-' ) {
 680                         // Allow these UI messages to be blanked out cleanly
 681                         return '';
 682                 }
 683
 684                 // Max content length = max comment length - length of the comment (excl. $1)
 685                 $text = $content->getTextForSummary( 255 - ( strlen( $reason ) - 2 ) );
 686
 687                 // Now replace the '$1' placeholder
 688                 $reason = str_replace( '$1', $text, $reason );
 689
 690                 return $reason;
 691         }
 692
 693         #@TODO: getSecondaryUpdatesForDeletion( Content ) returns an array of SecondaryDataUpdate objects
 694         #... or do that in the Content class?
 695
 696         /**
 697          * Get the Content object that needs to be saved in order to undo all revisions
 698          * between $undo and $undoafter. Revisions must belong to the same page,
 699          * must exist and must not be deleted
 700          * @param $current Revision the current text
 701          * @param $undo Revision the revision to undo
 702          * @param $undoafter Revision Must be an earlier revision than $undo
 703          * @return mixed string on success, false on failure
 704          */
 705         public function getUndoContent( Revision $current, Revision $undo, Revision $undoafter ) {
 706                 $cur_content = $current->getContent();
 707
 708                 if ( empty( $cur_content ) ) {
 709                         return false; // no page
 710                 }
 711
 712                 $undo_content = $undo->getContent();
 713                 $undoafter_content = $undoafter->getContent();
 714
 715                 if ( $cur_content->equals( $undo_content ) ) {
 716                         // No use doing a merge if it's just a straight revert.
 717                         return $undoafter_content;
 718                 }
 719
 720                 $undone_content = $this->merge3( $undo_content, $undoafter_content, $cur_content );
 721
 722                 return $undone_content;
 723         }
 724
 725         /**
 726          * Returns true for content models that support caching using the ParserCache mechanism.
 727          * See WikiPage::isParserCacheUser().
 728          *
 729          * @return bool
 730          */
 731         public function isParserCacheSupported() {
 732                 return true;
 733         }
 734
 735         /**
 736          * @param $page WikiPage the page that was deleted (note: $page->getId() must still return the old page ID!)
 737          *
 738          * @return array a list of SecondaryDataUpdate instances that will clean up the database ofter deletion.
 739          */
 740         public function getDeletionUpdates( WikiPage $page ) {
 741                 return array(
 742                         new LinksDeletionUpdate( $page ),
 743                 );
 744         }
 745 }
 746
 747
 748 abstract class TextContentHandler extends ContentHandler {
 749
 750         public function __construct( $modelId, $formats ) {
 751                 parent::__construct( $modelId, $formats );
 752         }
 753
 754         public function serializeContent( Content $content, $format = null ) {
 755                 $this->checkFormat( $format );
 756                 return $content->getNativeData();
 757         }
 758
 759         /**
 760          * attempts to merge differences between three versions.
 761          * Returns a new Content object for a clean merge and false for failure or a conflict.
 762          *
 763          * All three Content objects passed as parameters must have the same content model.
 764          *
 765          * This text-based implementation uses wfMerge().
 766          *
 767          * @param $oldContent String
 768          * @param $myContent String
 769          * @param $yourContent String
 770          * @return Content|Bool
 771          */
 772         public function merge3( Content $oldContent, Content $myContent, Content $yourContent ) {
 773                 $this->checkModelID( $oldContent->getModel() );
 774                 $this->checkModelID( $myContent->getModel() );
 775                 $this->checkModelID( $yourContent->getModel() );
 776
 777                 $format = $this->getDefaultFormat();
 778
 779                 $old = $this->serializeContent( $oldContent, $format );
 780                 $mine = $this->serializeContent( $myContent, $format );
 781                 $yours = $this->serializeContent( $yourContent, $format );
 782
 783                 $ok = wfMerge( $old, $mine, $yours, $result );
 784
 785                 if ( !$ok ) {
 786                         return false;
 787                 }
 788
 789                 if ( !$result ) {
 790                         return $this->makeEmptyContent();
 791                 }
 792
 793                 $mergedContent = $this->unserializeContent( $result, $format );
 794                 return $mergedContent;
 795         }
 796
 797
 798 }
 799 class WikitextContentHandler extends TextContentHandler {
 800
 801         public function __construct( $modelId = CONTENT_MODEL_WIKITEXT ) {
 802                 parent::__construct( $modelId, array( CONTENT_FORMAT_WIKITEXT ) );
 803         }
 804
 805         public function unserializeContent( $text, $format = null ) {
 806                 $this->checkFormat( $format );
 807
 808                 return new WikitextContent( $text );
 809         }
 810
 811         public function makeEmptyContent() {
 812                 return new WikitextContent( '' );
 813         }
 814
 815
 816 }
 817
 818 #XXX: make ScriptContentHandler base class with plugin interface for syntax highlighting?
 819
 820 class JavaScriptContentHandler extends TextContentHandler {
 821
 822         public function __construct( $modelId = CONTENT_MODEL_JAVASCRIPT ) {
 823                 parent::__construct( $modelId, array( CONTENT_FORMAT_JAVASCRIPT ) );
 824         }
 825
 826         public function unserializeContent( $text, $format = null ) {
 827                 $this->checkFormat( $format );
 828
 829                 return new JavaScriptContent( $text );
 830         }
 831
 832         public function makeEmptyContent() {
 833                 return new JavaScriptContent( '' );
 834         }
 835 }
 836
 837 class CssContentHandler extends TextContentHandler {
 838
 839         public function __construct( $modelId = CONTENT_MODEL_CSS ) {
 840                 parent::__construct( $modelId, array( CONTENT_FORMAT_CSS ) );
 841         }
 842
 843         public function unserializeContent( $text, $format = null ) {
 844                 $this->checkFormat( $format );
 845
 846                 return new CssContent( $text );
 847         }
 848
 849         public function makeEmptyContent() {
 850                 return new CssContent( '' );
 851         }
 852
 853 }