includes/content/ContentHandler.php

   1 <?php
   2
   3 /**
   4  * Exception representing a failure to serialize or unserialize a content object.
   5  */
   6 class MWContentSerializationException extends MWException {
   7
   8 }
   9
  10 /**
  11  * A content handler knows how do deal with a specific type of content on a wiki
  12  * page. Content is stored in the database in a serialized form (using a
  13  * serialization format a.k.a. MIME type) and is unserialized into its native
  14  * PHP representation (the content model), which is wrapped in an instance of
  15  * the appropriate subclass of Content.
  16  *
  17  * ContentHandler instances are stateless singletons that serve, among other
  18  * things, as a factory for Content objects. Generally, there is one subclass
  19  * of ContentHandler and one subclass of Content for every type of content model.
  20  *
  21  * Some content types have a flat model, that is, their native representation
  22  * is the same as their serialized form. Examples would be JavaScript and CSS
  23  * code. As of now, this also applies to wikitext (MediaWiki's default content
  24  * type), but wikitext content may be represented by a DOM or AST structure in
  25  * the future.
  26  *
  27  * @since 1.21
  28  */
  29 abstract class ContentHandler {
  30
  31         /**
  32          * Switch for enabling deprecation warnings. Used by ContentHandler::deprecated()
  33          * and ContentHandler::runLegacyHooks().
  34          *
  35          * Once the ContentHandler code has settled in a bit, this should be set to true to
  36          * make extensions etc. show warnings when using deprecated functions and hooks.
  37          */
  38         protected static $enableDeprecationWarnings = false;
  39
  40         /**
  41          * Convenience function for getting flat text from a Content object. This
  42          * should only be used in the context of backwards compatibility with code
  43          * that is not yet able to handle Content objects!
  44          *
  45          * If $content is null, this method returns the empty string.
  46          *
  47          * If $content is an instance of TextContent, this method returns the flat
  48          * text as returned by $content->getNativeData().
  49          *
  50          * If $content is not a TextContent object, the behavior of this method
  51          * depends on the global $wgContentHandlerTextFallback:
  52          * - If $wgContentHandlerTextFallback is 'fail' and $content is not a
  53          *   TextContent object, an MWException is thrown.
  54          * - If $wgContentHandlerTextFallback is 'serialize' and $content is not a
  55          *   TextContent object, $content->serialize() is called to get a string
  56          *   form of the content.
  57          * - If $wgContentHandlerTextFallback is 'ignore' and $content is not a
  58          *   TextContent object, this method returns null.
  59          * - otherwise, the behaviour is undefined.
  60          *
  61          * @since 1.21
  62          *
  63          * @static
  64          * @param $content Content|null
  65          * @return null|string the textual form of $content, if available
  66          * @throws MWException if $content is not an instance of TextContent and
  67          *   $wgContentHandlerTextFallback was set to 'fail'.
  68          */
  69         public static function getContentText( Content $content = null ) {
  70                 global $wgContentHandlerTextFallback;
  71
  72                 if ( is_null( $content ) ) {
  73                         return '';
  74                 }
  75
  76                 if ( $content instanceof TextContent ) {
  77                         return $content->getNativeData();
  78                 }
  79
  80                 if ( $wgContentHandlerTextFallback == 'fail' ) {
  81                         throw new MWException(
  82                                 "Attempt to get text from Content with model " .
  83                                 $content->getModel()
  84                         );
  85                 }
  86
  87                 if ( $wgContentHandlerTextFallback == 'serialize' ) {
  88                         return $content->serialize();
  89                 }
  90
  91                 return null;
  92         }
  93
  94         /**
  95          * Convenience function for creating a Content object from a given textual
  96          * representation.
  97          *
  98          * $text will be deserialized into a Content object of the model specified
  99          * by $modelId (or, if that is not given, $title->getContentModel()) using
 100          * the given format.
 101          *
 102          * @since 1.21
 103          *
 104          * @static
 105          *
 106          * @param $text string the textual representation, will be
 107          *    unserialized to create the Content object
 108          * @param $title null|Title the title of the page this text belongs to.
 109          *    Required if $modelId is not provided.
 110          * @param $modelId null|string the model to deserialize to. If not provided,
 111          *    $title->getContentModel() is used.
 112          * @param $format null|string the format to use for deserialization. If not
 113          *    given, the model's default format is used.
 114          *
 115          * @return Content a Content object representing $text
 116          *
 117          * @throw MWException if $model or $format is not supported or if $text can
 118          *    not be unserialized using $format.
 119          */
 120         public static function makeContent( $text, Title $title = null,
 121                 $modelId = null, $format = null )
 122         {
 123                 if ( is_null( $modelId ) ) {
 124                         if ( is_null( $title ) ) {
 125                                 throw new MWException( "Must provide a Title object or a content model ID." );
 126                         }
 127
 128                         $modelId = $title->getContentModel();
 129                 }
 130
 131                 $handler = ContentHandler::getForModelID( $modelId );
 132                 return $handler->unserializeContent( $text, $format );
 133         }
 134
 135         /**
 136          * Returns the name of the default content model to be used for the page
 137          * with the given title.
 138          *
 139          * Note: There should rarely be need to call this method directly.
 140          * To determine the actual content model for a given page, use
 141          * Title::getContentModel().
 142          *
 143          * Which model is to be used by default for the page is determined based
 144          * on several factors:
 145          * - The global setting $wgNamespaceContentModels specifies a content model
 146          *   per namespace.
 147          * - The hook ContentHandlerDefaultModelFor may be used to override the page's default
 148          *   model.
 149          * - Pages in NS_MEDIAWIKI and NS_USER default to the CSS or JavaScript
 150          *   model if they end in .js or .css, respectively.
 151          * - Pages in NS_MEDIAWIKI default to the wikitext model otherwise.
 152          * - The hook TitleIsCssOrJsPage may be used to force a page to use the CSS
 153          *   or JavaScript model. This is a compatibility feature. The ContentHandlerDefaultModelFor
 154          *   hook should be used instead if possible.
 155          * - The hook TitleIsWikitextPage may be used to force a page to use the
 156          *   wikitext model. This is a compatibility feature. The ContentHandlerDefaultModelFor
 157          *   hook should be used instead if possible.
 158          *
 159          * If none of the above applies, the wikitext model is used.
 160          *
 161          * Note: this is used by, and may thus not use, Title::getContentModel()
 162          *
 163          * @since 1.21
 164          *
 165          * @static
 166          * @param $title Title
 167          * @return null|string default model name for the page given by $title
 168          */
 169         public static function getDefaultModelFor( Title $title ) {
 170                 global $wgNamespaceContentModels;
 171
 172                 // NOTE: this method must not rely on $title->getContentModel() directly or indirectly,
 173                 //       because it is used to initialize the mContentModel member.
 174
 175                 $ns = $title->getNamespace();
 176
 177                 $ext = false;
 178                 $m = null;
 179                 $model = null;
 180
 181                 if ( !empty( $wgNamespaceContentModels[ $ns ] ) ) {
 182                         $model = $wgNamespaceContentModels[ $ns ];
 183                 }
 184
 185                 // Hook can determine default model
 186                 if ( !wfRunHooks( 'ContentHandlerDefaultModelFor', array( $title, &$model ) ) ) {
 187                         if ( !is_null( $model ) ) {
 188                                 return $model;
 189                         }
 190                 }
 191
 192                 // Could this page contain custom CSS or JavaScript, based on the title?
 193                 $isCssOrJsPage = NS_MEDIAWIKI == $ns && preg_match( '!\.(css|js)$!u', $title->getText(), $m );
 194                 if ( $isCssOrJsPage ) {
 195                         $ext = $m[1];
 196                 }
 197
 198                 // Hook can force JS/CSS
 199                 wfRunHooks( 'TitleIsCssOrJsPage', array( $title, &$isCssOrJsPage ) );
 200
 201                 // Is this a .css subpage of a user page?
 202                 $isJsCssSubpage = NS_USER == $ns
 203                         && !$isCssOrJsPage
 204                         && preg_match( "/\\/.*\\.(js|css)$/", $title->getText(), $m );
 205                 if ( $isJsCssSubpage ) {
 206                         $ext = $m[1];
 207                 }
 208
 209                 // Is this wikitext, according to $wgNamespaceContentModels or the DefaultModelFor hook?
 210                 $isWikitext = is_null( $model ) || $model == CONTENT_MODEL_WIKITEXT;
 211                 $isWikitext = $isWikitext && !$isCssOrJsPage && !$isJsCssSubpage;
 212
 213                 // Hook can override $isWikitext
 214                 wfRunHooks( 'TitleIsWikitextPage', array( $title, &$isWikitext ) );
 215
 216                 if ( !$isWikitext ) {
 217                         switch ( $ext ) {
 218                                 case 'js':
 219                                         return CONTENT_MODEL_JAVASCRIPT;
 220                                 case 'css':
 221                                         return CONTENT_MODEL_CSS;
 222                                 default:
 223                                         return is_null( $model ) ? CONTENT_MODEL_TEXT : $model;
 224                         }
 225                 }
 226
 227                 // We established that it must be wikitext
 228
 229                 return CONTENT_MODEL_WIKITEXT;
 230         }
 231
 232         /**
 233          * Returns the appropriate ContentHandler singleton for the given title.
 234          *
 235          * @since 1.21
 236          *
 237          * @static
 238          * @param $title Title
 239          * @return ContentHandler
 240          */
 241         public static function getForTitle( Title $title ) {
 242                 $modelId = $title->getContentModel();
 243                 return ContentHandler::getForModelID( $modelId );
 244         }
 245
 246         /**
 247          * Returns the appropriate ContentHandler singleton for the given Content
 248          * object.
 249          *
 250          * @since 1.21
 251          *
 252          * @static
 253          * @param $content Content
 254          * @return ContentHandler
 255          */
 256         public static function getForContent( Content $content ) {
 257                 $modelId = $content->getModel();
 258                 return ContentHandler::getForModelID( $modelId );
 259         }
 260
 261         /**
 262          * @var Array A Cache of ContentHandler instances by model id
 263          */
 264         static $handlers;
 265
 266         /**
 267          * Returns the ContentHandler singleton for the given model ID. Use the
 268          * CONTENT_MODEL_XXX constants to identify the desired content model.
 269          *
 270          * ContentHandler singletons are taken from the global $wgContentHandlers
 271          * array. Keys in that array are model names, the values are either
 272          * ContentHandler singleton objects, or strings specifying the appropriate
 273          * subclass of ContentHandler.
 274          *
 275          * If a class name is encountered when looking up the singleton for a given
 276          * model name, the class is instantiated and the class name is replaced by
 277          * the resulting singleton in $wgContentHandlers.
 278          *
 279          * If no ContentHandler is defined for the desired $modelId, the
 280          * ContentHandler may be provided by the ContentHandlerForModelID hook.
 281          * If no ContentHandler can be determined, an MWException is raised.
 282          *
 283          * @since 1.21
 284          *
 285          * @static
 286          * @param $modelId String The ID of the content model for which to get a
 287          *    handler. Use CONTENT_MODEL_XXX constants.
 288          * @return ContentHandler The ContentHandler singleton for handling the
 289          *    model given by $modelId
 290          * @throws MWException if no handler is known for $modelId.
 291          */
 292         public static function getForModelID( $modelId ) {
 293                 global $wgContentHandlers;
 294
 295                 if ( isset( ContentHandler::$handlers[$modelId] ) ) {
 296                         return ContentHandler::$handlers[$modelId];
 297                 }
 298
 299                 if ( empty( $wgContentHandlers[$modelId] ) ) {
 300                         $handler = null;
 301
 302                         wfRunHooks( 'ContentHandlerForModelID', array( $modelId, &$handler ) );
 303
 304                         if ( $handler === null ) {
 305                                 throw new MWException( "No handler for model #$modelId registered in \$wgContentHandlers" );
 306                         }
 307
 308                         if ( !( $handler instanceof ContentHandler ) ) {
 309                                 throw new MWException( "ContentHandlerForModelID must supply a ContentHandler instance" );
 310                         }
 311                 } else {
 312                         $class = $wgContentHandlers[$modelId];
 313                         $handler = new $class( $modelId );
 314
 315                         if ( !( $handler instanceof ContentHandler ) ) {
 316                                 throw new MWException( "$class from \$wgContentHandlers is not compatible with ContentHandler" );
 317                         }
 318                 }
 319
 320                 ContentHandler::$handlers[$modelId] = $handler;
 321                 return ContentHandler::$handlers[$modelId];
 322         }
 323
 324         /**
 325          * Returns the localized name for a given content model.
 326          *
 327          * Model names are localized using system messages. Message keys
 328          * have the form content-model-$name, where $name is getContentModelName( $id ).
 329          *
 330          * @static
 331          * @param $name String The content model ID, as given by a CONTENT_MODEL_XXX
 332          *    constant or returned by Revision::getContentModel().
 333          *
 334          * @return string The content format's localized name.
 335          * @throws MWException if the model id isn't known.
 336          */
 337         public static function getLocalizedName( $name ) {
 338                 $key = "content-model-$name";
 339
 340                 $msg = wfMessage( $key );
 341
 342                 return $msg->exists() ? $msg->plain() : $name;
 343         }
 344
 345         public static function getContentModels() {
 346                 global $wgContentHandlers;
 347
 348                 return array_keys( $wgContentHandlers );
 349         }
 350
 351         public static function getAllContentFormats() {
 352                 global $wgContentHandlers;
 353
 354                 $formats = array();
 355
 356                 foreach ( $wgContentHandlers as $model => $class ) {
 357                         $handler = ContentHandler::getForModelID( $model );
 358                         $formats = array_merge( $formats, $handler->getSupportedFormats() );
 359                 }
 360
 361                 $formats = array_unique( $formats );
 362                 return $formats;
 363         }
 364
 365         // ------------------------------------------------------------------------
 366
 367         protected $mModelID;
 368         protected $mSupportedFormats;
 369
 370         /**
 371          * Constructor, initializing the ContentHandler instance with its model ID
 372          * and a list of supported formats. Values for the parameters are typically
 373          * provided as literals by subclass's constructors.
 374          *
 375          * @param $modelId String (use CONTENT_MODEL_XXX constants).
 376          * @param $formats array List for supported serialization formats
 377          *    (typically as MIME types)
 378          */
 379         public function __construct( $modelId, $formats ) {
 380                 $this->mModelID = $modelId;
 381                 $this->mSupportedFormats = $formats;
 382
 383                 $this->mModelName = preg_replace( '/(Content)?Handler$/', '', get_class( $this ) );
 384                 $this->mModelName = preg_replace( '/[_\\\\]/', '', $this->mModelName );
 385                 $this->mModelName = strtolower( $this->mModelName );
 386         }
 387
 388         /**
 389          * Serializes a Content object of the type supported by this ContentHandler.
 390          *
 391          * @since 1.21
 392          *
 393          * @abstract
 394          * @param $content Content The Content object to serialize
 395          * @param $format null|String The desired serialization format
 396          * @return string Serialized form of the content
 397          */
 398         public abstract function serializeContent( Content $content, $format = null );
 399
 400         /**
 401          * Unserializes a Content object of the type supported by this ContentHandler.
 402          *
 403          * @since 1.21
 404          *
 405          * @abstract
 406          * @param $blob string serialized form of the content
 407          * @param $format null|String the format used for serialization
 408          * @return Content the Content object created by deserializing $blob
 409          */
 410         public abstract function unserializeContent( $blob, $format = null );
 411
 412         /**
 413          * Creates an empty Content object of the type supported by this
 414          * ContentHandler.
 415          *
 416          * @since 1.21
 417          *
 418          * @return Content
 419          */
 420         public abstract function makeEmptyContent();
 421
 422         /**
 423          * Creates a new Content object that acts as a redirect to the given page,
 424          * or null of redirects are not supported by this content model.
 425          *
 426          * This default implementation always returns null. Subclasses supporting redirects
 427          * must override this method.
 428          *
 429          * @since 1.21
 430          *
 431          * @param Title $destination the page to redirect to.
 432          *
 433          * @return Content
 434          */
 435         public function makeRedirectContent( Title $destination ) {
 436                 return null;
 437         }
 438
 439         /**
 440          * Returns the model id that identifies the content model this
 441          * ContentHandler can handle. Use with the CONTENT_MODEL_XXX constants.
 442          *
 443          * @since 1.21
 444          *
 445          * @return String The model ID
 446          */
 447         public function getModelID() {
 448                 return $this->mModelID;
 449         }
 450
 451         /**
 452          * Throws an MWException if $model_id is not the ID of the content model
 453          * supported by this ContentHandler.
 454          *
 455          * @since 1.21
 456          *
 457          * @param String $model_id The model to check
 458          *
 459          * @throws MWException
 460          */
 461         protected function checkModelID( $model_id ) {
 462                 if ( $model_id !== $this->mModelID ) {
 463                         throw new MWException( "Bad content model: " .
 464                                 "expected {$this->mModelID} " .
 465                                 "but got $model_id." );
 466                 }
 467         }
 468
 469         /**
 470          * Returns a list of serialization formats supported by the
 471          * serializeContent() and unserializeContent() methods of this
 472          * ContentHandler.
 473          *
 474          * @since 1.21
 475          *
 476          * @return array of serialization formats as MIME type like strings
 477          */
 478         public function getSupportedFormats() {
 479                 return $this->mSupportedFormats;
 480         }
 481
 482         /**
 483          * The format used for serialization/deserialization by default by this
 484          * ContentHandler.
 485          *
 486          * This default implementation will return the first element of the array
 487          * of formats that was passed to the constructor.
 488          *
 489          * @since 1.21
 490          *
 491          * @return string the name of the default serialization format as a MIME type
 492          */
 493         public function getDefaultFormat() {
 494                 return $this->mSupportedFormats[0];
 495         }
 496
 497         /**
 498          * Returns true if $format is a serialization format supported by this
 499          * ContentHandler, and false otherwise.
 500          *
 501          * Note that if $format is null, this method always returns true, because
 502          * null means "use the default format".
 503          *
 504          * @since 1.21
 505          *
 506          * @param $format string the serialization format to check
 507          * @return bool
 508          */
 509         public function isSupportedFormat( $format ) {
 510
 511                 if ( !$format ) {
 512                         return true; // this means "use the default"
 513                 }
 514
 515                 return in_array( $format, $this->mSupportedFormats );
 516         }
 517
 518         /**
 519          * Throws an MWException if isSupportedFormat( $format ) is not true.
 520          * Convenient for checking whether a format provided as a parameter is
 521          * actually supported.
 522          *
 523          * @param $format string the serialization format to check
 524          *
 525          * @throws MWException
 526          */
 527         protected function checkFormat( $format ) {
 528                 if ( !$this->isSupportedFormat( $format ) ) {
 529                         throw new MWException(
 530                                 "Format $format is not supported for content model "
 531                                 . $this->getModelID()
 532                         );
 533                 }
 534         }
 535
 536         /**
 537          * Returns overrides for action handlers.
 538          * Classes listed here will be used instead of the default one when
 539          * (and only when) $wgActions[$action] === true. This allows subclasses
 540          * to override the default action handlers.
 541          *
 542          * @since 1.21
 543          *
 544          * @return Array
 545          */
 546         public function getActionOverrides() {
 547                 return array();
 548         }
 549
 550         /**
 551          * Factory for creating an appropriate DifferenceEngine for this content model.
 552          *
 553          * @since 1.21
 554          *
 555          * @param $context IContextSource context to use, anything else will be
 556          *    ignored
 557          * @param $old Integer Old ID we want to show and diff with.
 558          * @param $new int|string String either 'prev' or 'next'.
 559          * @param $rcid Integer ??? FIXME (default 0)
 560          * @param $refreshCache boolean If set, refreshes the diff cache
 561          * @param $unhide boolean If set, allow viewing deleted revs
 562          *
 563          * @return DifferenceEngine
 564          */
 565         public function createDifferenceEngine( IContextSource $context,
 566                 $old = 0, $new = 0,
 567                 $rcid = 0, # FIXME: use everywhere!
 568                 $refreshCache = false, $unhide = false
 569         ) {
 570                 $this->checkModelID( $context->getTitle()->getContentModel() );
 571
 572                 $diffEngineClass = $this->getDiffEngineClass();
 573
 574                 return new $diffEngineClass( $context, $old, $new, $rcid, $refreshCache, $unhide );
 575         }
 576
 577         /**
 578          * Get the language in which the content of the given page is written.
 579          *
 580          * This default implementation just returns $wgContLang (except for pages in the MediaWiki namespace)
 581          *
 582          * Note that the pages language is not cacheable, since it may in some cases depend on user settings.
 583          *
 584          * Also note that the page language may or may not depend on the actual content of the page,
 585          * that is, this method may load the content in order to determine the language.
 586          *
 587          * @since 1.21
 588          *
 589          * @param Title        $title the page to determine the language for.
 590          * @param Content|null $content the page's content, if you have it handy, to avoid reloading it.
 591          *
 592          * @return Language the page's language
 593          */
 594         public function getPageLanguage( Title $title, Content $content = null ) {
 595                 global $wgContLang;
 596
 597                 if ( $title->getNamespace() == NS_MEDIAWIKI ) {
 598                         // Parse mediawiki messages with correct target language
 599                         list( /* $unused */, $lang ) = MessageCache::singleton()->figureMessage( $title->getText() );
 600                         return wfGetLangObj( $lang );
 601                 }
 602
 603                 return $wgContLang;
 604         }
 605
 606         /**
 607          * Get the language in which the content of this page is written when
 608          * viewed by user. Defaults to $this->getPageLanguage(), but if the user
 609          * specified a preferred variant, the variant will be used.
 610          *
 611          * This default implementation just returns $this->getPageLanguage( $title, $content ) unless
 612          * the user specified a preferred variant.
 613          *
 614          * Note that the pages view language is not cacheable, since it depends on user settings.
 615          *
 616          * Also note that the page language may or may not depend on the actual content of the page,
 617          * that is, this method may load the content in order to determine the language.
 618          *
 619          * @since 1.21
 620          *
 621          * @param Title        $title the page to determine the language for.
 622          * @param Content|null $content the page's content, if you have it handy, to avoid reloading it.
 623          *
 624          * @return Language the page's language for viewing
 625          */
 626         public function getPageViewLanguage( Title $title, Content $content = null ) {
 627                 $pageLang = $this->getPageLanguage( $title, $content );
 628
 629                 if ( $title->getNamespace() !== NS_MEDIAWIKI ) {
 630                         // If the user chooses a variant, the content is actually
 631                         // in a language whose code is the variant code.
 632                         $variant = $pageLang->getPreferredVariant();
 633                         if ( $pageLang->getCode() !== $variant ) {
 634                                 $pageLang = Language::factory( $variant );
 635                         }
 636                 }
 637
 638                 return $pageLang;
 639         }
 640
 641         /**
 642          * Determines whether the content type handled by this ContentHandler
 643          * can be used on the given page.
 644          *
 645          * This default implementation always returns true.
 646          * Subclasses may override this to restrict the use of this content model to specific locations,
 647          * typically based on the namespace or some other aspect of the title, such as a special suffix
 648          * (e.g. ".svg" for SVG content).
 649          *
 650          * @param Title $title the page's title.
 651          *
 652          * @return bool true if content of this kind can be used on the given page, false otherwise.
 653          */
 654         public function canBeUsedOn( Title $title ) {
 655                 return true;
 656         }
 657
 658         /**
 659          * Returns the name of the diff engine to use.
 660          *
 661          * @since 1.21
 662          *
 663          * @return string
 664          */
 665         protected function getDiffEngineClass() {
 666                 return 'DifferenceEngine';
 667         }
 668
 669         /**
 670          * Attempts to merge differences between three versions.
 671          * Returns a new Content object for a clean merge and false for failure or
 672          * a conflict.
 673          *
 674          * This default implementation always returns false.
 675          *
 676          * @since 1.21
 677          *
 678          * @param $oldContent Content|string  String
 679          * @param $myContent Content|string   String
 680          * @param $yourContent Content|string String
 681          *
 682          * @return Content|Bool
 683          */
 684         public function merge3( Content $oldContent, Content $myContent, Content $yourContent ) {
 685                 return false;
 686         }
 687
 688         /**
 689          * Return an applicable auto-summary if one exists for the given edit.
 690          *
 691          * @since 1.21
 692          *
 693          * @param $oldContent Content|null: the previous text of the page.
 694          * @param $newContent Content|null: The submitted text of the page.
 695          * @param $flags int Bit mask: a bit mask of flags submitted for the edit.
 696          *
 697          * @return string An appropriate auto-summary, or an empty string.
 698          */
 699         public function getAutosummary( Content $oldContent = null, Content $newContent = null, $flags ) {
 700                 global $wgContLang;
 701
 702                 // Decide what kind of auto-summary is needed.
 703
 704                 // Redirect auto-summaries
 705
 706                 /**
 707                  * @var $ot Title
 708                  * @var $rt Title
 709                  */
 710
 711                 $ot = !is_null( $oldContent ) ? $oldContent->getRedirectTarget() : null;
 712                 $rt = !is_null( $newContent ) ? $newContent->getRedirectTarget() : null;
 713
 714                 if ( is_object( $rt ) ) {
 715                         if ( !is_object( $ot )
 716                                 || !$rt->equals( $ot )
 717                                 || $ot->getFragment() != $rt->getFragment() )
 718                         {
 719                                 $truncatedtext = $newContent->getTextForSummary(
 720                                         250
 721                                                 - strlen( wfMessage( 'autoredircomment' )->inContentLanguage()->text() )
 722                                                 - strlen( $rt->getFullText() ) );
 723
 724                                 return wfMessage( 'autoredircomment', $rt->getFullText() )
 725                                                 ->rawParams( $truncatedtext )->inContentLanguage()->text();
 726                         }
 727                 }
 728
 729                 // New page auto-summaries
 730                 if ( $flags & EDIT_NEW && $newContent->getSize() > 0 ) {
 731                         // If they're making a new article, give its text, truncated, in
 732                         // the summary.
 733
 734                         $truncatedtext = $newContent->getTextForSummary(
 735                                 200 - strlen( wfMessage( 'autosumm-new' )->inContentLanguage()->text() ) );
 736
 737                         return wfMessage( 'autosumm-new' )->rawParams( $truncatedtext )
 738                                         ->inContentLanguage()->text();
 739                 }
 740
 741                 // Blanking auto-summaries
 742                 if ( !empty( $oldContent ) && $oldContent->getSize() > 0 && $newContent->getSize() == 0 ) {
 743                         return wfMessage( 'autosumm-blank' )->inContentLanguage()->text();
 744                 } elseif ( !empty( $oldContent )
 745                         && $oldContent->getSize() > 10 * $newContent->getSize()
 746                         && $newContent->getSize() < 500 )
 747                 {
 748                         // Removing more than 90% of the article
 749
 750                         $truncatedtext = $newContent->getTextForSummary(
 751                                 200 - strlen( wfMessage( 'autosumm-replace' )->inContentLanguage()->text() ) );
 752
 753                         return wfMessage( 'autosumm-replace' )->rawParams( $truncatedtext )
 754                                         ->inContentLanguage()->text();
 755                 }
 756
 757                 // If we reach this point, there's no applicable auto-summary for our
 758                 // case, so our auto-summary is empty.
 759                 return '';
 760         }
 761
 762         /**
 763          * Auto-generates a deletion reason
 764          *
 765          * @since 1.21
 766          *
 767          * @param $title Title: the page's title
 768          * @param &$hasHistory Boolean: whether the page has a history
 769          * @return mixed String containing deletion reason or empty string, or
 770          *    boolean false if no revision occurred
 771          *
 772          * @XXX &$hasHistory is extremely ugly, it's here because
 773          * WikiPage::getAutoDeleteReason() and Article::getReason()
 774          * have it / want it.
 775          */
 776         public function getAutoDeleteReason( Title $title, &$hasHistory ) {
 777                 $dbw = wfGetDB( DB_MASTER );
 778
 779                 // Get the last revision
 780                 $rev = Revision::newFromTitle( $title );
 781
 782                 if ( is_null( $rev ) ) {
 783                         return false;
 784                 }
 785
 786                 // Get the article's contents
 787                 $content = $rev->getContent();
 788                 $blank = false;
 789
 790                 $this->checkModelID( $content->getModel() );
 791
 792                 // If the page is blank, use the text from the previous revision,
 793                 // which can only be blank if there's a move/import/protect dummy
 794                 // revision involved
 795                 if ( $content->getSize() == 0 ) {
 796                         $prev = $rev->getPrevious();
 797
 798                         if ( $prev )    {
 799                                 $content = $prev->getContent();
 800                                 $blank = true;
 801                         }
 802                 }
 803
 804                 // Find out if there was only one contributor
 805                 // Only scan the last 20 revisions
 806                 $res = $dbw->select( 'revision', 'rev_user_text',
 807                         array(
 808                                 'rev_page' => $title->getArticleID(),
 809                                 $dbw->bitAnd( 'rev_deleted', Revision::DELETED_USER ) . ' = 0'
 810                         ),
 811                         __METHOD__,
 812                         array( 'LIMIT' => 20 )
 813                 );
 814
 815                 if ( $res === false ) {
 816                         // This page has no revisions, which is very weird
 817                         return false;
 818                 }
 819
 820                 $hasHistory = ( $res->numRows() > 1 );
 821                 $row = $dbw->fetchObject( $res );
 822
 823                 if ( $row ) { // $row is false if the only contributor is hidden
 824                         $onlyAuthor = $row->rev_user_text;
 825                         // Try to find a second contributor
 826                         foreach ( $res as $row ) {
 827                                 if ( $row->rev_user_text != $onlyAuthor ) { // Bug 22999
 828                                         $onlyAuthor = false;
 829                                         break;
 830                                 }
 831                         }
 832                 } else {
 833                         $onlyAuthor = false;
 834                 }
 835
 836                 // Generate the summary with a '$1' placeholder
 837                 if ( $blank ) {
 838                         // The current revision is blank and the one before is also
 839                         // blank. It's just not our lucky day
 840                         $reason = wfMessage( 'exbeforeblank', '$1' )->inContentLanguage()->text();
 841                 } else {
 842                         if ( $onlyAuthor ) {
 843                                 $reason = wfMessage(
 844                                         'excontentauthor',
 845                                         '$1',
 846                                         $onlyAuthor
 847                                 )->inContentLanguage()->text();
 848                         } else {
 849                                 $reason = wfMessage( 'excontent', '$1' )->inContentLanguage()->text();
 850                         }
 851                 }
 852
 853                 if ( $reason == '-' ) {
 854                         // Allow these UI messages to be blanked out cleanly
 855                         return '';
 856                 }
 857
 858                 // Max content length = max comment length - length of the comment (excl. $1)
 859                 $text = $content->getTextForSummary( 255 - ( strlen( $reason ) - 2 ) );
 860
 861                 // Now replace the '$1' placeholder
 862                 $reason = str_replace( '$1', $text, $reason );
 863
 864                 return $reason;
 865         }
 866
 867         /**
 868          * Get the Content object that needs to be saved in order to undo all revisions
 869          * between $undo and $undoafter. Revisions must belong to the same page,
 870          * must exist and must not be deleted.
 871          *
 872          * @since 1.21
 873          *
 874          * @param $current Revision The current text
 875          * @param $undo Revision The revision to undo
 876          * @param $undoafter Revision Must be an earlier revision than $undo
 877          *
 878          * @return mixed String on success, false on failure
 879          */
 880         public function getUndoContent( Revision $current, Revision $undo, Revision $undoafter ) {
 881                 $cur_content = $current->getContent();
 882
 883                 if ( empty( $cur_content ) ) {
 884                         return false; // no page
 885                 }
 886
 887                 $undo_content = $undo->getContent();
 888                 $undoafter_content = $undoafter->getContent();
 889
 890                 $this->checkModelID( $cur_content->getModel() );
 891                 $this->checkModelID( $undo_content->getModel() );
 892                 $this->checkModelID( $undoafter_content->getModel() );
 893
 894                 if ( $cur_content->equals( $undo_content ) ) {
 895                         // No use doing a merge if it's just a straight revert.
 896                         return $undoafter_content;
 897                 }
 898
 899                 $undone_content = $this->merge3( $undo_content, $undoafter_content, $cur_content );
 900
 901                 return $undone_content;
 902         }
 903
 904         /**
 905          * Get parser options suitable for rendering the primary article wikitext
 906          *
 907          * @param IContextSource|User|string $context One of the following:
 908          *        - IContextSource: Use the User and the Language of the provided
 909          *                                            context
 910          *        - User: Use the provided User object and $wgLang for the language,
 911          *                                            so use an IContextSource object if possible.
 912          *        - 'canonical': Canonical options (anonymous user with default
 913          *                                            preferences and content language).
 914          *
 915          * @param IContextSource|User|string $context
 916          *
 917          * @throws MWException
 918          * @return ParserOptions
 919          */
 920         public function makeParserOptions( $context ) {
 921                 global $wgContLang;
 922
 923                 if ( $context instanceof IContextSource ) {
 924                         $options = ParserOptions::newFromContext( $context );
 925                 } elseif ( $context instanceof User ) { // settings per user (even anons)
 926                         $options = ParserOptions::newFromUser( $context );
 927                 } elseif ( $context === 'canonical' ) { // canonical settings
 928                         $options = ParserOptions::newFromUserAndLang( new User, $wgContLang );
 929                 } else {
 930                         throw new MWException( "Bad context for parser options: $context" );
 931                 }
 932
 933                 $options->enableLimitReport(); // show inclusion/loop reports
 934                 $options->setTidy( true ); // fix bad HTML
 935
 936                 return $options;
 937         }
 938
 939         /**
 940          * Returns true for content models that support caching using the
 941          * ParserCache mechanism. See WikiPage::isParserCacheUsed().
 942          *
 943          * @since 1.21
 944          *
 945          * @return bool
 946          */
 947         public function isParserCacheSupported() {
 948                 return false;
 949         }
 950
 951         /**
 952          * Returns true if this content model supports sections.
 953          *
 954          * This default implementation returns false.
 955          *
 956          * @return boolean whether sections are supported.
 957          */
 958         public function supportsSections() {
 959                 return false;
 960         }
 961
 962         /**
 963          * Logs a deprecation warning, visible if $wgDevelopmentWarnings, but only if
 964          * self::$enableDeprecationWarnings is set to true.
 965          *
 966          * @param String      $func The name of the deprecated function
 967          * @param string      $version The version since the method is deprecated. Usually 1.21
 968          *                    for ContentHandler related stuff.
 969          * @param String|bool $component: Component to which the function belongs.
 970          *                                If false, it is assumed the function is in MediaWiki core.
 971          *
 972          * @see ContentHandler::$enableDeprecationWarnings
 973          * @see wfDeprecated
 974          */
 975         public static function deprecated( $func, $version, $component = false ) {
 976                 if ( self::$enableDeprecationWarnings ) {
 977                         wfDeprecated( $func, $version, $component, 3 );
 978                 }
 979         }
 980
 981         /**
 982          * Call a legacy hook that uses text instead of Content objects.
 983          * Will log a warning when a matching hook function is registered.
 984          * If the textual representation of the content is changed by the
 985          * hook function, a new Content object is constructed from the new
 986          * text.
 987          *
 988          * @param $event String: event name
 989          * @param $args Array: parameters passed to hook functions
 990          * @param $warn bool: whether to log a warning.
 991          *                    Default to self::$enableDeprecationWarnings.
 992          *                    May be set to false for testing.
 993          *
 994          * @return Boolean True if no handler aborted the hook
 995          *
 996          * @see ContentHandler::$enableDeprecationWarnings
 997          */
 998         public static function runLegacyHooks( $event, $args = array(),
 999                         $warn = null ) {
1000
1001                 if ( $warn === null ) {
1002                         $warn = self::$enableDeprecationWarnings;
1003                 }
1004
1005                 if ( !Hooks::isRegistered( $event ) ) {
1006                         return true; // nothing to do here
1007                 }
1008
1009                 if ( $warn ) {
1010                         // Log information about which handlers are registered for the legacy hook,
1011                         // so we can find and fix them.
1012
1013                         $handlers = Hooks::getHandlers( $event );
1014                         $handlerInfo = array();
1015
1016                         wfSuppressWarnings();
1017
1018                         foreach ( $handlers as $handler ) {
1019                                 $info = '';
1020
1021                                 if ( is_array( $handler ) ) {
1022                                         if ( is_object( $handler[0] ) ) {
1023                                                 $info = get_class( $handler[0] );
1024                                         } else {
1025                                                 $info = $handler[0];
1026                                         }
1027
1028                                         if ( isset( $handler[1] ) ) {
1029                                                 $info .= '::' . $handler[1];
1030                                         }
1031                                 } else if ( is_object( $handler ) ) {
1032                                         $info = get_class( $handler[0] );
1033                                         $info .= '::on' . $event;
1034                                 } else {
1035                                         $info = $handler;
1036                                 }
1037
1038                                 $handlerInfo[] = $info;
1039                         }
1040
1041                         wfRestoreWarnings();
1042
1043                         wfWarn( "Using obsolete hook $event via ContentHandler::runLegacyHooks()! Handlers: " . implode(', ', $handlerInfo), 2 );
1044                 }
1045
1046                 // convert Content objects to text
1047                 $contentObjects = array();
1048                 $contentTexts = array();
1049
1050                 foreach ( $args as $k => $v ) {
1051                         if ( $v instanceof Content ) {
1052                                 /* @var Content $v */
1053
1054                                 $contentObjects[$k] = $v;
1055
1056                                 $v = $v->serialize();
1057                                 $contentTexts[ $k ] = $v;
1058                                 $args[ $k ] = $v;
1059                         }
1060                 }
1061
1062                 // call the hook functions
1063                 $ok = wfRunHooks( $event, $args );
1064
1065                 // see if the hook changed the text
1066                 foreach ( $contentTexts as $k => $orig ) {
1067                         /* @var Content $content */
1068
1069                         $modified = $args[ $k ];
1070                         $content = $contentObjects[$k];
1071
1072                         if ( $modified !== $orig ) {
1073                                 // text was changed, create updated Content object
1074                                 $content = $content->getContentHandler()->unserializeContent( $modified );
1075                         }
1076
1077                         $args[ $k ] = $content;
1078                 }
1079
1080                 return $ok;
1081         }
1082 }
1083
1084 /**
1085  * @since 1.21
1086  */
1087 abstract class TextContentHandler extends ContentHandler {
1088
1089         public function __construct( $modelId, $formats ) {
1090                 parent::__construct( $modelId, $formats );
1091         }
1092
1093         /**
1094          * Returns the content's text as-is.
1095          *
1096          * @param $content Content
1097          * @param $format string|null
1098          * @return mixed
1099          */
1100         public function serializeContent( Content $content, $format = null ) {
1101                 $this->checkFormat( $format );
1102                 return $content->getNativeData();
1103         }
1104
1105         /**
1106          * Attempts to merge differences between three versions. Returns a new
1107          * Content object for a clean merge and false for failure or a conflict.
1108          *
1109          * All three Content objects passed as parameters must have the same
1110          * content model.
1111          *
1112          * This text-based implementation uses wfMerge().
1113          *
1114          * @param $oldContent \Content|string  String
1115          * @param $myContent \Content|string   String
1116          * @param $yourContent \Content|string String
1117          *
1118          * @return Content|Bool
1119          */
1120         public function merge3( Content $oldContent, Content $myContent, Content $yourContent ) {
1121                 $this->checkModelID( $oldContent->getModel() );
1122                 $this->checkModelID( $myContent->getModel() );
1123                 $this->checkModelID( $yourContent->getModel() );
1124
1125                 $format = $this->getDefaultFormat();
1126
1127                 $old = $this->serializeContent( $oldContent, $format );
1128                 $mine = $this->serializeContent( $myContent, $format );
1129                 $yours = $this->serializeContent( $yourContent, $format );
1130
1131                 $ok = wfMerge( $old, $mine, $yours, $result );
1132
1133                 if ( !$ok ) {
1134                         return false;
1135                 }
1136
1137                 if ( !$result ) {
1138                         return $this->makeEmptyContent();
1139                 }
1140
1141                 $mergedContent = $this->unserializeContent( $result, $format );
1142                 return $mergedContent;
1143         }
1144
1145 }
1146
1147 /**
1148  * @since 1.21
1149  */
1150 class WikitextContentHandler extends TextContentHandler {
1151
1152         public function __construct( $modelId = CONTENT_MODEL_WIKITEXT ) {
1153                 parent::__construct( $modelId, array( CONTENT_FORMAT_WIKITEXT ) );
1154         }
1155
1156         public function unserializeContent( $text, $format = null ) {
1157                 $this->checkFormat( $format );
1158
1159                 return new WikitextContent( $text );
1160         }
1161
1162         /**
1163          * @see ContentHandler::makeEmptyContent
1164          *
1165          * @return Content
1166          */
1167         public function makeEmptyContent() {
1168                 return new WikitextContent( '' );
1169         }
1170
1171
1172         /**
1173          * Returns a WikitextContent object representing a redirect to the given destination page.
1174          *
1175          * @see ContentHandler::makeRedirectContent
1176          *
1177          * @param Title $destination the page to redirect to.
1178          *
1179          * @return Content
1180          */
1181         public function makeRedirectContent( Title $destination ) {
1182                 $mwRedir = MagicWord::get( 'redirect' );
1183                 $redirectText = $mwRedir->getSynonym( 0 ) . ' [[' . $destination->getPrefixedText() . "]]\n";
1184
1185                 return new WikitextContent( $redirectText );
1186         }
1187
1188         /**
1189          * Returns true because wikitext supports sections.
1190          *
1191          * @return boolean whether sections are supported.
1192          */
1193         public function supportsSections() {
1194                 return true;
1195         }
1196
1197         /**
1198          * Returns true, because wikitext supports caching using the
1199          * ParserCache mechanism.
1200          *
1201          * @since 1.21
1202          * @return bool
1203          */
1204         public function isParserCacheSupported() {
1205                 return true;
1206         }
1207 }
1208
1209 # XXX: make ScriptContentHandler base class, do highlighting stuff there?
1210
1211 /**
1212  * @since 1.21
1213  */
1214 class JavaScriptContentHandler extends TextContentHandler {
1215
1216         public function __construct( $modelId = CONTENT_MODEL_JAVASCRIPT ) {
1217                 parent::__construct( $modelId, array( CONTENT_FORMAT_JAVASCRIPT ) );
1218         }
1219
1220         public function unserializeContent( $text, $format = null ) {
1221                 $this->checkFormat( $format );
1222
1223                 return new JavaScriptContent( $text );
1224         }
1225
1226         public function makeEmptyContent() {
1227                 return new JavaScriptContent( '' );
1228         }
1229
1230         /**
1231          * Returns the english language, because JS is english, and should be handled as such.
1232          *
1233          * @return Language wfGetLangObj( 'en' )
1234          *
1235          * @see ContentHandler::getPageLanguage()
1236          */
1237         public function getPageLanguage( Title $title, Content $content = null ) {
1238                 return wfGetLangObj( 'en' );
1239         }
1240
1241         /**
1242          * Returns the english language, because CSS is english, and should be handled as such.
1243          *
1244          * @return Language wfGetLangObj( 'en' )
1245          *
1246          * @see ContentHandler::getPageViewLanguage()
1247          */
1248         public function getPageViewLanguage( Title $title, Content $content = null ) {
1249                 return wfGetLangObj( 'en' );
1250         }
1251 }
1252
1253 /**
1254  * @since 1.21
1255  */
1256 class CssContentHandler extends TextContentHandler {
1257
1258         public function __construct( $modelId = CONTENT_MODEL_CSS ) {
1259                 parent::__construct( $modelId, array( CONTENT_FORMAT_CSS ) );
1260         }
1261
1262         public function unserializeContent( $text, $format = null ) {
1263                 $this->checkFormat( $format );
1264
1265                 return new CssContent( $text );
1266         }
1267
1268         public function makeEmptyContent() {
1269                 return new CssContent( '' );
1270         }
1271
1272         /**
1273          * Returns the english language, because CSS is english, and should be handled as such.
1274          *
1275          * @return Language wfGetLangObj( 'en' )
1276          *
1277          * @see ContentHandler::getPageLanguage()
1278          */
1279         public function getPageLanguage( Title $title, Content $content = null ) {
1280                 return wfGetLangObj( 'en' );
1281         }
1282
1283         /**
1284          * Returns the english language, because CSS is english, and should be handled as such.
1285          *
1286          * @return Language wfGetLangObj( 'en' )
1287          *
1288          * @see ContentHandler::getPageViewLanguage()
1289          */
1290         public function getPageViewLanguage( Title $title, Content $content = null ) {
1291                 return wfGetLangObj( 'en' );
1292         }
1293 }