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  * This program is free software; you can redistribute it and/or modify
  28  * it under the terms of the GNU General Public License as published by
  29  * the Free Software Foundation; either version 2 of the License, or
  30  * (at your option) any later version.
  31  *
  32  * This program is distributed in the hope that it will be useful,
  33  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  34  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  35  * GNU General Public License for more details.
  36  *
  37  * You should have received a copy of the GNU General Public License along
  38  * with this program; if not, write to the Free Software Foundation, Inc.,
  39  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  40  * http://www.gnu.org/copyleft/gpl.html
  41  *
  42  * @since 1.21
  43  *
  44  * @file
  45  * @ingroup Content
  46  *
  47  * @author Daniel Kinzler
  48  */
  49 abstract class ContentHandler {
  50
  51         /**
  52          * Switch for enabling deprecation warnings. Used by ContentHandler::deprecated()
  53          * and ContentHandler::runLegacyHooks().
  54          *
  55          * Once the ContentHandler code has settled in a bit, this should be set to true to
  56          * make extensions etc. show warnings when using deprecated functions and hooks.
  57          */
  58         protected static $enableDeprecationWarnings = false;
  59
  60         /**
  61          * Convenience function for getting flat text from a Content object. This
  62          * should only be used in the context of backwards compatibility with code
  63          * that is not yet able to handle Content objects!
  64          *
  65          * If $content is null, this method returns the empty string.
  66          *
  67          * If $content is an instance of TextContent, this method returns the flat
  68          * text as returned by $content->getNativeData().
  69          *
  70          * If $content is not a TextContent object, the behavior of this method
  71          * depends on the global $wgContentHandlerTextFallback:
  72          * - If $wgContentHandlerTextFallback is 'fail' and $content is not a
  73          *   TextContent object, an MWException is thrown.
  74          * - If $wgContentHandlerTextFallback is 'serialize' and $content is not a
  75          *   TextContent object, $content->serialize() is called to get a string
  76          *   form of the content.
  77          * - If $wgContentHandlerTextFallback is 'ignore' and $content is not a
  78          *   TextContent object, this method returns null.
  79          * - otherwise, the behaviour is undefined.
  80          *
  81          * @since 1.21
  82          *
  83          * @static
  84          * @param $content Content|null
  85          * @return null|string the textual form of $content, if available
  86          * @throws MWException if $content is not an instance of TextContent and
  87          *   $wgContentHandlerTextFallback was set to 'fail'.
  88          */
  89         public static function getContentText( Content $content = null ) {
  90                 global $wgContentHandlerTextFallback;
  91
  92                 if ( is_null( $content ) ) {
  93                         return '';
  94                 }
  95
  96                 if ( $content instanceof TextContent ) {
  97                         return $content->getNativeData();
  98                 }
  99
 100                 if ( $wgContentHandlerTextFallback == 'fail' ) {
 101                         throw new MWException(
 102                                 "Attempt to get text from Content with model " .
 103                                 $content->getModel()
 104                         );
 105                 }
 106
 107                 if ( $wgContentHandlerTextFallback == 'serialize' ) {
 108                         return $content->serialize();
 109                 }
 110
 111                 return null;
 112         }
 113
 114         /**
 115          * Convenience function for creating a Content object from a given textual
 116          * representation.
 117          *
 118          * $text will be deserialized into a Content object of the model specified
 119          * by $modelId (or, if that is not given, $title->getContentModel()) using
 120          * the given format.
 121          *
 122          * @since 1.21
 123          *
 124          * @static
 125          *
 126          * @param $text string the textual representation, will be
 127          *    unserialized to create the Content object
 128          * @param $title null|Title the title of the page this text belongs to.
 129          *    Required if $modelId is not provided.
 130          * @param $modelId null|string the model to deserialize to. If not provided,
 131          *    $title->getContentModel() is used.
 132          * @param $format null|string the format to use for deserialization. If not
 133          *    given, the model's default format is used.
 134          *
 135          * @return Content a Content object representing $text
 136          *
 137          * @throw MWException if $model or $format is not supported or if $text can
 138          *    not be unserialized using $format.
 139          */
 140         public static function makeContent( $text, Title $title = null,
 141                 $modelId = null, $format = null )
 142         {
 143                 if ( is_null( $modelId ) ) {
 144                         if ( is_null( $title ) ) {
 145                                 throw new MWException( "Must provide a Title object or a content model ID." );
 146                         }
 147
 148                         $modelId = $title->getContentModel();
 149                 }
 150
 151                 $handler = ContentHandler::getForModelID( $modelId );
 152                 return $handler->unserializeContent( $text, $format );
 153         }
 154
 155         /**
 156          * Returns the name of the default content model to be used for the page
 157          * with the given title.
 158          *
 159          * Note: There should rarely be need to call this method directly.
 160          * To determine the actual content model for a given page, use
 161          * Title::getContentModel().
 162          *
 163          * Which model is to be used by default for the page is determined based
 164          * on several factors:
 165          * - The global setting $wgNamespaceContentModels specifies a content model
 166          *   per namespace.
 167          * - The hook ContentHandlerDefaultModelFor may be used to override the page's default
 168          *   model.
 169          * - Pages in NS_MEDIAWIKI and NS_USER default to the CSS or JavaScript
 170          *   model if they end in .js or .css, respectively.
 171          * - Pages in NS_MEDIAWIKI default to the wikitext model otherwise.
 172          * - The hook TitleIsCssOrJsPage may be used to force a page to use the CSS
 173          *   or JavaScript model. This is a compatibility feature. The ContentHandlerDefaultModelFor
 174          *   hook should be used instead if possible.
 175          * - The hook TitleIsWikitextPage may be used to force a page to use the
 176          *   wikitext model. This is a compatibility feature. The ContentHandlerDefaultModelFor
 177          *   hook should be used instead if possible.
 178          *
 179          * If none of the above applies, the wikitext model is used.
 180          *
 181          * Note: this is used by, and may thus not use, Title::getContentModel()
 182          *
 183          * @since 1.21
 184          *
 185          * @static
 186          * @param $title Title
 187          * @return null|string default model name for the page given by $title
 188          */
 189         public static function getDefaultModelFor( Title $title ) {
 190                 global $wgNamespaceContentModels;
 191
 192                 // NOTE: this method must not rely on $title->getContentModel() directly or indirectly,
 193                 //       because it is used to initialize the mContentModel member.
 194
 195                 $ns = $title->getNamespace();
 196
 197                 $ext = false;
 198                 $m = null;
 199                 $model = null;
 200
 201                 if ( !empty( $wgNamespaceContentModels[ $ns ] ) ) {
 202                         $model = $wgNamespaceContentModels[ $ns ];
 203                 }
 204
 205                 // Hook can determine default model
 206                 if ( !wfRunHooks( 'ContentHandlerDefaultModelFor', array( $title, &$model ) ) ) {
 207                         if ( !is_null( $model ) ) {
 208                                 return $model;
 209                         }
 210                 }
 211
 212                 // Could this page contain custom CSS or JavaScript, based on the title?
 213                 $isCssOrJsPage = NS_MEDIAWIKI == $ns && preg_match( '!\.(css|js)$!u', $title->getText(), $m );
 214                 if ( $isCssOrJsPage ) {
 215                         $ext = $m[1];
 216                 }
 217
 218                 // Hook can force JS/CSS
 219                 wfRunHooks( 'TitleIsCssOrJsPage', array( $title, &$isCssOrJsPage ) );
 220
 221                 // Is this a .css subpage of a user page?
 222                 $isJsCssSubpage = NS_USER == $ns
 223                         && !$isCssOrJsPage
 224                         && preg_match( "/\\/.*\\.(js|css)$/", $title->getText(), $m );
 225                 if ( $isJsCssSubpage ) {
 226                         $ext = $m[1];
 227                 }
 228
 229                 // Is this wikitext, according to $wgNamespaceContentModels or the DefaultModelFor hook?
 230                 $isWikitext = is_null( $model ) || $model == CONTENT_MODEL_WIKITEXT;
 231                 $isWikitext = $isWikitext && !$isCssOrJsPage && !$isJsCssSubpage;
 232
 233                 // Hook can override $isWikitext
 234                 wfRunHooks( 'TitleIsWikitextPage', array( $title, &$isWikitext ) );
 235
 236                 if ( !$isWikitext ) {
 237                         switch ( $ext ) {
 238                                 case 'js':
 239                                         return CONTENT_MODEL_JAVASCRIPT;
 240                                 case 'css':
 241                                         return CONTENT_MODEL_CSS;
 242                                 default:
 243                                         return is_null( $model ) ? CONTENT_MODEL_TEXT : $model;
 244                         }
 245                 }
 246
 247                 // We established that it must be wikitext
 248
 249                 return CONTENT_MODEL_WIKITEXT;
 250         }
 251
 252         /**
 253          * Returns the appropriate ContentHandler singleton for the given title.
 254          *
 255          * @since 1.21
 256          *
 257          * @static
 258          * @param $title Title
 259          * @return ContentHandler
 260          */
 261         public static function getForTitle( Title $title ) {
 262                 $modelId = $title->getContentModel();
 263                 return ContentHandler::getForModelID( $modelId );
 264         }
 265
 266         /**
 267          * Returns the appropriate ContentHandler singleton for the given Content
 268          * object.
 269          *
 270          * @since 1.21
 271          *
 272          * @static
 273          * @param $content Content
 274          * @return ContentHandler
 275          */
 276         public static function getForContent( Content $content ) {
 277                 $modelId = $content->getModel();
 278                 return ContentHandler::getForModelID( $modelId );
 279         }
 280
 281         /**
 282          * @var Array A Cache of ContentHandler instances by model id
 283          */
 284         static $handlers;
 285
 286         /**
 287          * Returns the ContentHandler singleton for the given model ID. Use the
 288          * CONTENT_MODEL_XXX constants to identify the desired content model.
 289          *
 290          * ContentHandler singletons are taken from the global $wgContentHandlers
 291          * array. Keys in that array are model names, the values are either
 292          * ContentHandler singleton objects, or strings specifying the appropriate
 293          * subclass of ContentHandler.
 294          *
 295          * If a class name is encountered when looking up the singleton for a given
 296          * model name, the class is instantiated and the class name is replaced by
 297          * the resulting singleton in $wgContentHandlers.
 298          *
 299          * If no ContentHandler is defined for the desired $modelId, the
 300          * ContentHandler may be provided by the ContentHandlerForModelID hook.
 301          * If no ContentHandler can be determined, an MWException is raised.
 302          *
 303          * @since 1.21
 304          *
 305          * @static
 306          * @param $modelId String The ID of the content model for which to get a
 307          *    handler. Use CONTENT_MODEL_XXX constants.
 308          * @return ContentHandler The ContentHandler singleton for handling the
 309          *    model given by $modelId
 310          * @throws MWException if no handler is known for $modelId.
 311          */
 312         public static function getForModelID( $modelId ) {
 313                 global $wgContentHandlers;
 314
 315                 if ( isset( ContentHandler::$handlers[$modelId] ) ) {
 316                         return ContentHandler::$handlers[$modelId];
 317                 }
 318
 319                 if ( empty( $wgContentHandlers[$modelId] ) ) {
 320                         $handler = null;
 321
 322                         wfRunHooks( 'ContentHandlerForModelID', array( $modelId, &$handler ) );
 323
 324                         if ( $handler === null ) {
 325                                 throw new MWException( "No handler for model '$modelId'' registered in \$wgContentHandlers" );
 326                         }
 327
 328                         if ( !( $handler instanceof ContentHandler ) ) {
 329                                 throw new MWException( "ContentHandlerForModelID must supply a ContentHandler instance" );
 330                         }
 331                 } else {
 332                         $class = $wgContentHandlers[$modelId];
 333                         $handler = new $class( $modelId );
 334
 335                         if ( !( $handler instanceof ContentHandler ) ) {
 336                                 throw new MWException( "$class from \$wgContentHandlers is not compatible with ContentHandler" );
 337                         }
 338                 }
 339
 340                 ContentHandler::$handlers[$modelId] = $handler;
 341                 return ContentHandler::$handlers[$modelId];
 342         }
 343
 344         /**
 345          * Returns the localized name for a given content model.
 346          *
 347          * Model names are localized using system messages. Message keys
 348          * have the form content-model-$name, where $name is getContentModelName( $id ).
 349          *
 350          * @static
 351          * @param $name String The content model ID, as given by a CONTENT_MODEL_XXX
 352          *    constant or returned by Revision::getContentModel().
 353          *
 354          * @return string The content format's localized name.
 355          * @throws MWException if the model id isn't known.
 356          */
 357         public static function getLocalizedName( $name ) {
 358                 $key = "content-model-$name";
 359
 360                 $msg = wfMessage( $key );
 361
 362                 return $msg->exists() ? $msg->plain() : $name;
 363         }
 364
 365         public static function getContentModels() {
 366                 global $wgContentHandlers;
 367
 368                 return array_keys( $wgContentHandlers );
 369         }
 370
 371         public static function getAllContentFormats() {
 372                 global $wgContentHandlers;
 373
 374                 $formats = array();
 375
 376                 foreach ( $wgContentHandlers as $model => $class ) {
 377                         $handler = ContentHandler::getForModelID( $model );
 378                         $formats = array_merge( $formats, $handler->getSupportedFormats() );
 379                 }
 380
 381                 $formats = array_unique( $formats );
 382                 return $formats;
 383         }
 384
 385         // ------------------------------------------------------------------------
 386
 387         protected $mModelID;
 388         protected $mSupportedFormats;
 389
 390         /**
 391          * Constructor, initializing the ContentHandler instance with its model ID
 392          * and a list of supported formats. Values for the parameters are typically
 393          * provided as literals by subclass's constructors.
 394          *
 395          * @param $modelId String (use CONTENT_MODEL_XXX constants).
 396          * @param $formats array List for supported serialization formats
 397          *    (typically as MIME types)
 398          */
 399         public function __construct( $modelId, $formats ) {
 400                 $this->mModelID = $modelId;
 401                 $this->mSupportedFormats = $formats;
 402
 403                 $this->mModelName = preg_replace( '/(Content)?Handler$/', '', get_class( $this ) );
 404                 $this->mModelName = preg_replace( '/[_\\\\]/', '', $this->mModelName );
 405                 $this->mModelName = strtolower( $this->mModelName );
 406         }
 407
 408         /**
 409          * Serializes a Content object of the type supported by this ContentHandler.
 410          *
 411          * @since 1.21
 412          *
 413          * @abstract
 414          * @param $content Content The Content object to serialize
 415          * @param $format null|String The desired serialization format
 416          * @return string Serialized form of the content
 417          */
 418         public abstract function serializeContent( Content $content, $format = null );
 419
 420         /**
 421          * Unserializes a Content object of the type supported by this ContentHandler.
 422          *
 423          * @since 1.21
 424          *
 425          * @abstract
 426          * @param $blob string serialized form of the content
 427          * @param $format null|String the format used for serialization
 428          * @return Content the Content object created by deserializing $blob
 429          */
 430         public abstract function unserializeContent( $blob, $format = null );
 431
 432         /**
 433          * Creates an empty Content object of the type supported by this
 434          * ContentHandler.
 435          *
 436          * @since 1.21
 437          *
 438          * @return Content
 439          */
 440         public abstract function makeEmptyContent();
 441
 442         /**
 443          * Creates a new Content object that acts as a redirect to the given page,
 444          * or null of redirects are not supported by this content model.
 445          *
 446          * This default implementation always returns null. Subclasses supporting redirects
 447          * must override this method.
 448          *
 449          * @since 1.21
 450          *
 451          * @param Title $destination the page to redirect to.
 452          *
 453          * @return Content
 454          */
 455         public function makeRedirectContent( Title $destination ) {
 456                 return null;
 457         }
 458
 459         /**
 460          * Returns the model id that identifies the content model this
 461          * ContentHandler can handle. Use with the CONTENT_MODEL_XXX constants.
 462          *
 463          * @since 1.21
 464          *
 465          * @return String The model ID
 466          */
 467         public function getModelID() {
 468                 return $this->mModelID;
 469         }
 470
 471         /**
 472          * Throws an MWException if $model_id is not the ID of the content model
 473          * supported by this ContentHandler.
 474          *
 475          * @since 1.21
 476          *
 477          * @param String $model_id The model to check
 478          *
 479          * @throws MWException
 480          */
 481         protected function checkModelID( $model_id ) {
 482                 if ( $model_id !== $this->mModelID ) {
 483                         throw new MWException( "Bad content model: " .
 484                                 "expected {$this->mModelID} " .
 485                                 "but got $model_id." );
 486                 }
 487         }
 488
 489         /**
 490          * Returns a list of serialization formats supported by the
 491          * serializeContent() and unserializeContent() methods of this
 492          * ContentHandler.
 493          *
 494          * @since 1.21
 495          *
 496          * @return array of serialization formats as MIME type like strings
 497          */
 498         public function getSupportedFormats() {
 499                 return $this->mSupportedFormats;
 500         }
 501
 502         /**
 503          * The format used for serialization/deserialization by default by this
 504          * ContentHandler.
 505          *
 506          * This default implementation will return the first element of the array
 507          * of formats that was passed to the constructor.
 508          *
 509          * @since 1.21
 510          *
 511          * @return string the name of the default serialization format as a MIME type
 512          */
 513         public function getDefaultFormat() {
 514                 return $this->mSupportedFormats[0];
 515         }
 516
 517         /**
 518          * Returns true if $format is a serialization format supported by this
 519          * ContentHandler, and false otherwise.
 520          *
 521          * Note that if $format is null, this method always returns true, because
 522          * null means "use the default format".
 523          *
 524          * @since 1.21
 525          *
 526          * @param $format string the serialization format to check
 527          * @return bool
 528          */
 529         public function isSupportedFormat( $format ) {
 530
 531                 if ( !$format ) {
 532                         return true; // this means "use the default"
 533                 }
 534
 535                 return in_array( $format, $this->mSupportedFormats );
 536         }
 537
 538         /**
 539          * Throws an MWException if isSupportedFormat( $format ) is not true.
 540          * Convenient for checking whether a format provided as a parameter is
 541          * actually supported.
 542          *
 543          * @param $format string the serialization format to check
 544          *
 545          * @throws MWException
 546          */
 547         protected function checkFormat( $format ) {
 548                 if ( !$this->isSupportedFormat( $format ) ) {
 549                         throw new MWException(
 550                                 "Format $format is not supported for content model "
 551                                 . $this->getModelID()
 552                         );
 553                 }
 554         }
 555
 556         /**
 557          * Returns overrides for action handlers.
 558          * Classes listed here will be used instead of the default one when
 559          * (and only when) $wgActions[$action] === true. This allows subclasses
 560          * to override the default action handlers.
 561          *
 562          * @since 1.21
 563          *
 564          * @return Array
 565          */
 566         public function getActionOverrides() {
 567                 return array();
 568         }
 569
 570         /**
 571          * Factory for creating an appropriate DifferenceEngine for this content model.
 572          *
 573          * @since 1.21
 574          *
 575          * @param $context IContextSource context to use, anything else will be
 576          *    ignored
 577          * @param $old Integer Old ID we want to show and diff with.
 578          * @param $new int|string String either 'prev' or 'next'.
 579          * @param $rcid Integer ??? FIXME (default 0)
 580          * @param $refreshCache boolean If set, refreshes the diff cache
 581          * @param $unhide boolean If set, allow viewing deleted revs
 582          *
 583          * @return DifferenceEngine
 584          */
 585         public function createDifferenceEngine( IContextSource $context,
 586                 $old = 0, $new = 0,
 587                 $rcid = 0, # FIXME: use everywhere!
 588                 $refreshCache = false, $unhide = false
 589         ) {
 590                 $this->checkModelID( $context->getTitle()->getContentModel() );
 591
 592                 $diffEngineClass = $this->getDiffEngineClass();
 593
 594                 return new $diffEngineClass( $context, $old, $new, $rcid, $refreshCache, $unhide );
 595         }
 596
 597         /**
 598          * Get the language in which the content of the given page is written.
 599          *
 600          * This default implementation just returns $wgContLang (except for pages in the MediaWiki namespace)
 601          *
 602          * Note that the pages language is not cacheable, since it may in some cases depend on user settings.
 603          *
 604          * Also note that the page language may or may not depend on the actual content of the page,
 605          * that is, this method may load the content in order to determine the language.
 606          *
 607          * @since 1.21
 608          *
 609          * @param Title        $title the page to determine the language for.
 610          * @param Content|null $content the page's content, if you have it handy, to avoid reloading it.
 611          *
 612          * @return Language the page's language
 613          */
 614         public function getPageLanguage( Title $title, Content $content = null ) {
 615                 global $wgContLang;
 616
 617                 if ( $title->getNamespace() == NS_MEDIAWIKI ) {
 618                         // Parse mediawiki messages with correct target language
 619                         list( /* $unused */, $lang ) = MessageCache::singleton()->figureMessage( $title->getText() );
 620                         return wfGetLangObj( $lang );
 621                 }
 622
 623                 return $wgContLang;
 624         }
 625
 626         /**
 627          * Get the language in which the content of this page is written when
 628          * viewed by user. Defaults to $this->getPageLanguage(), but if the user
 629          * specified a preferred variant, the variant will be used.
 630          *
 631          * This default implementation just returns $this->getPageLanguage( $title, $content ) unless
 632          * the user specified a preferred variant.
 633          *
 634          * Note that the pages view language is not cacheable, since it depends on user settings.
 635          *
 636          * Also note that the page language may or may not depend on the actual content of the page,
 637          * that is, this method may load the content in order to determine the language.
 638          *
 639          * @since 1.21
 640          *
 641          * @param Title        $title the page to determine the language for.
 642          * @param Content|null $content the page's content, if you have it handy, to avoid reloading it.
 643          *
 644          * @return Language the page's language for viewing
 645          */
 646         public function getPageViewLanguage( Title $title, Content $content = null ) {
 647                 $pageLang = $this->getPageLanguage( $title, $content );
 648
 649                 if ( $title->getNamespace() !== NS_MEDIAWIKI ) {
 650                         // If the user chooses a variant, the content is actually
 651                         // in a language whose code is the variant code.
 652                         $variant = $pageLang->getPreferredVariant();
 653                         if ( $pageLang->getCode() !== $variant ) {
 654                                 $pageLang = Language::factory( $variant );
 655                         }
 656                 }
 657
 658                 return $pageLang;
 659         }
 660
 661         /**
 662          * Determines whether the content type handled by this ContentHandler
 663          * can be used on the given page.
 664          *
 665          * This default implementation always returns true.
 666          * Subclasses may override this to restrict the use of this content model to specific locations,
 667          * typically based on the namespace or some other aspect of the title, such as a special suffix
 668          * (e.g. ".svg" for SVG content).
 669          *
 670          * @param Title $title the page's title.
 671          *
 672          * @return bool true if content of this kind can be used on the given page, false otherwise.
 673          */
 674         public function canBeUsedOn( Title $title ) {
 675                 return true;
 676         }
 677
 678         /**
 679          * Returns the name of the diff engine to use.
 680          *
 681          * @since 1.21
 682          *
 683          * @return string
 684          */
 685         protected function getDiffEngineClass() {
 686                 return 'DifferenceEngine';
 687         }
 688
 689         /**
 690          * Attempts to merge differences between three versions.
 691          * Returns a new Content object for a clean merge and false for failure or
 692          * a conflict.
 693          *
 694          * This default implementation always returns false.
 695          *
 696          * @since 1.21
 697          *
 698          * @param $oldContent Content|string  String
 699          * @param $myContent Content|string   String
 700          * @param $yourContent Content|string String
 701          *
 702          * @return Content|Bool
 703          */
 704         public function merge3( Content $oldContent, Content $myContent, Content $yourContent ) {
 705                 return false;
 706         }
 707
 708         /**
 709          * Return an applicable auto-summary if one exists for the given edit.
 710          *
 711          * @since 1.21
 712          *
 713          * @param $oldContent Content|null: the previous text of the page.
 714          * @param $newContent Content|null: The submitted text of the page.
 715          * @param $flags int Bit mask: a bit mask of flags submitted for the edit.
 716          *
 717          * @return string An appropriate auto-summary, or an empty string.
 718          */
 719         public function getAutosummary( Content $oldContent = null, Content $newContent = null, $flags ) {
 720                 global $wgContLang;
 721
 722                 // Decide what kind of auto-summary is needed.
 723
 724                 // Redirect auto-summaries
 725
 726                 /**
 727                  * @var $ot Title
 728                  * @var $rt Title
 729                  */
 730
 731                 $ot = !is_null( $oldContent ) ? $oldContent->getRedirectTarget() : null;
 732                 $rt = !is_null( $newContent ) ? $newContent->getRedirectTarget() : null;
 733
 734                 if ( is_object( $rt ) ) {
 735                         if ( !is_object( $ot )
 736                                 || !$rt->equals( $ot )
 737                                 || $ot->getFragment() != $rt->getFragment() )
 738                         {
 739                                 $truncatedtext = $newContent->getTextForSummary(
 740                                         250
 741                                                 - strlen( wfMessage( 'autoredircomment' )->inContentLanguage()->text() )
 742                                                 - strlen( $rt->getFullText() ) );
 743
 744                                 return wfMessage( 'autoredircomment', $rt->getFullText() )
 745                                                 ->rawParams( $truncatedtext )->inContentLanguage()->text();
 746                         }
 747                 }
 748
 749                 // New page auto-summaries
 750                 if ( $flags & EDIT_NEW && $newContent->getSize() > 0 ) {
 751                         // If they're making a new article, give its text, truncated, in
 752                         // the summary.
 753
 754                         $truncatedtext = $newContent->getTextForSummary(
 755                                 200 - strlen( wfMessage( 'autosumm-new' )->inContentLanguage()->text() ) );
 756
 757                         return wfMessage( 'autosumm-new' )->rawParams( $truncatedtext )
 758                                         ->inContentLanguage()->text();
 759                 }
 760
 761                 // Blanking auto-summaries
 762                 if ( !empty( $oldContent ) && $oldContent->getSize() > 0 && $newContent->getSize() == 0 ) {
 763                         return wfMessage( 'autosumm-blank' )->inContentLanguage()->text();
 764                 } elseif ( !empty( $oldContent )
 765                         && $oldContent->getSize() > 10 * $newContent->getSize()
 766                         && $newContent->getSize() < 500 )
 767                 {
 768                         // Removing more than 90% of the article
 769
 770                         $truncatedtext = $newContent->getTextForSummary(
 771                                 200 - strlen( wfMessage( 'autosumm-replace' )->inContentLanguage()->text() ) );
 772
 773                         return wfMessage( 'autosumm-replace' )->rawParams( $truncatedtext )
 774                                         ->inContentLanguage()->text();
 775                 }
 776
 777                 // If we reach this point, there's no applicable auto-summary for our
 778                 // case, so our auto-summary is empty.
 779                 return '';
 780         }
 781
 782         /**
 783          * Auto-generates a deletion reason
 784          *
 785          * @since 1.21
 786          *
 787          * @param $title Title: the page's title
 788          * @param &$hasHistory Boolean: whether the page has a history
 789          * @return mixed String containing deletion reason or empty string, or
 790          *    boolean false if no revision occurred
 791          *
 792          * @XXX &$hasHistory is extremely ugly, it's here because
 793          * WikiPage::getAutoDeleteReason() and Article::getReason()
 794          * have it / want it.
 795          */
 796         public function getAutoDeleteReason( Title $title, &$hasHistory ) {
 797                 $dbw = wfGetDB( DB_MASTER );
 798
 799                 // Get the last revision
 800                 $rev = Revision::newFromTitle( $title );
 801
 802                 if ( is_null( $rev ) ) {
 803                         return false;
 804                 }
 805
 806                 // Get the article's contents
 807                 $content = $rev->getContent();
 808                 $blank = false;
 809
 810                 $this->checkModelID( $content->getModel() );
 811
 812                 // If the page is blank, use the text from the previous revision,
 813                 // which can only be blank if there's a move/import/protect dummy
 814                 // revision involved
 815                 if ( $content->getSize() == 0 ) {
 816                         $prev = $rev->getPrevious();
 817
 818                         if ( $prev )    {
 819                                 $content = $prev->getContent();
 820                                 $blank = true;
 821                         }
 822                 }
 823
 824                 // Find out if there was only one contributor
 825                 // Only scan the last 20 revisions
 826                 $res = $dbw->select( 'revision', 'rev_user_text',
 827                         array(
 828                                 'rev_page' => $title->getArticleID(),
 829                                 $dbw->bitAnd( 'rev_deleted', Revision::DELETED_USER ) . ' = 0'
 830                         ),
 831                         __METHOD__,
 832                         array( 'LIMIT' => 20 )
 833                 );
 834
 835                 if ( $res === false ) {
 836                         // This page has no revisions, which is very weird
 837                         return false;
 838                 }
 839
 840                 $hasHistory = ( $res->numRows() > 1 );
 841                 $row = $dbw->fetchObject( $res );
 842
 843                 if ( $row ) { // $row is false if the only contributor is hidden
 844                         $onlyAuthor = $row->rev_user_text;
 845                         // Try to find a second contributor
 846                         foreach ( $res as $row ) {
 847                                 if ( $row->rev_user_text != $onlyAuthor ) { // Bug 22999
 848                                         $onlyAuthor = false;
 849                                         break;
 850                                 }
 851                         }
 852                 } else {
 853                         $onlyAuthor = false;
 854                 }
 855
 856                 // Generate the summary with a '$1' placeholder
 857                 if ( $blank ) {
 858                         // The current revision is blank and the one before is also
 859                         // blank. It's just not our lucky day
 860                         $reason = wfMessage( 'exbeforeblank', '$1' )->inContentLanguage()->text();
 861                 } else {
 862                         if ( $onlyAuthor ) {
 863                                 $reason = wfMessage(
 864                                         'excontentauthor',
 865                                         '$1',
 866                                         $onlyAuthor
 867                                 )->inContentLanguage()->text();
 868                         } else {
 869                                 $reason = wfMessage( 'excontent', '$1' )->inContentLanguage()->text();
 870                         }
 871                 }
 872
 873                 if ( $reason == '-' ) {
 874                         // Allow these UI messages to be blanked out cleanly
 875                         return '';
 876                 }
 877
 878                 // Max content length = max comment length - length of the comment (excl. $1)
 879                 $text = $content->getTextForSummary( 255 - ( strlen( $reason ) - 2 ) );
 880
 881                 // Now replace the '$1' placeholder
 882                 $reason = str_replace( '$1', $text, $reason );
 883
 884                 return $reason;
 885         }
 886
 887         /**
 888          * Get the Content object that needs to be saved in order to undo all revisions
 889          * between $undo and $undoafter. Revisions must belong to the same page,
 890          * must exist and must not be deleted.
 891          *
 892          * @since 1.21
 893          *
 894          * @param $current Revision The current text
 895          * @param $undo Revision The revision to undo
 896          * @param $undoafter Revision Must be an earlier revision than $undo
 897          *
 898          * @return mixed String on success, false on failure
 899          */
 900         public function getUndoContent( Revision $current, Revision $undo, Revision $undoafter ) {
 901                 $cur_content = $current->getContent();
 902
 903                 if ( empty( $cur_content ) ) {
 904                         return false; // no page
 905                 }
 906
 907                 $undo_content = $undo->getContent();
 908                 $undoafter_content = $undoafter->getContent();
 909
 910                 $this->checkModelID( $cur_content->getModel() );
 911                 $this->checkModelID( $undo_content->getModel() );
 912                 $this->checkModelID( $undoafter_content->getModel() );
 913
 914                 if ( $cur_content->equals( $undo_content ) ) {
 915                         // No use doing a merge if it's just a straight revert.
 916                         return $undoafter_content;
 917                 }
 918
 919                 $undone_content = $this->merge3( $undo_content, $undoafter_content, $cur_content );
 920
 921                 return $undone_content;
 922         }
 923
 924         /**
 925          * Get parser options suitable for rendering the primary article wikitext
 926          *
 927          * @param IContextSource|User|string $context One of the following:
 928          *        - IContextSource: Use the User and the Language of the provided
 929          *                                            context
 930          *        - User: Use the provided User object and $wgLang for the language,
 931          *                                            so use an IContextSource object if possible.
 932          *        - 'canonical': Canonical options (anonymous user with default
 933          *                                            preferences and content language).
 934          *
 935          * @param IContextSource|User|string $context
 936          *
 937          * @throws MWException
 938          * @return ParserOptions
 939          */
 940         public function makeParserOptions( $context ) {
 941                 global $wgContLang;
 942
 943                 if ( $context instanceof IContextSource ) {
 944                         $options = ParserOptions::newFromContext( $context );
 945                 } elseif ( $context instanceof User ) { // settings per user (even anons)
 946                         $options = ParserOptions::newFromUser( $context );
 947                 } elseif ( $context === 'canonical' ) { // canonical settings
 948                         $options = ParserOptions::newFromUserAndLang( new User, $wgContLang );
 949                 } else {
 950                         throw new MWException( "Bad context for parser options: $context" );
 951                 }
 952
 953                 $options->enableLimitReport(); // show inclusion/loop reports
 954                 $options->setTidy( true ); // fix bad HTML
 955
 956                 return $options;
 957         }
 958
 959         /**
 960          * Returns true for content models that support caching using the
 961          * ParserCache mechanism. See WikiPage::isParserCacheUsed().
 962          *
 963          * @since 1.21
 964          *
 965          * @return bool
 966          */
 967         public function isParserCacheSupported() {
 968                 return false;
 969         }
 970
 971         /**
 972          * Returns true if this content model supports sections.
 973          *
 974          * This default implementation returns false.
 975          *
 976          * @return boolean whether sections are supported.
 977          */
 978         public function supportsSections() {
 979                 return false;
 980         }
 981
 982         /**
 983          * Logs a deprecation warning, visible if $wgDevelopmentWarnings, but only if
 984          * self::$enableDeprecationWarnings is set to true.
 985          *
 986          * @param String      $func The name of the deprecated function
 987          * @param string      $version The version since the method is deprecated. Usually 1.21
 988          *                    for ContentHandler related stuff.
 989          * @param String|bool $component: Component to which the function belongs.
 990          *                                If false, it is assumed the function is in MediaWiki core.
 991          *
 992          * @see ContentHandler::$enableDeprecationWarnings
 993          * @see wfDeprecated
 994          */
 995         public static function deprecated( $func, $version, $component = false ) {
 996                 if ( self::$enableDeprecationWarnings ) {
 997                         wfDeprecated( $func, $version, $component, 3 );
 998                 }
 999         }
1000
1001         /**
1002          * Call a legacy hook that uses text instead of Content objects.
1003          * Will log a warning when a matching hook function is registered.
1004          * If the textual representation of the content is changed by the
1005          * hook function, a new Content object is constructed from the new
1006          * text.
1007          *
1008          * @param $event String: event name
1009          * @param $args Array: parameters passed to hook functions
1010          * @param $warn bool: whether to log a warning.
1011          *                    Default to self::$enableDeprecationWarnings.
1012          *                    May be set to false for testing.
1013          *
1014          * @return Boolean True if no handler aborted the hook
1015          *
1016          * @see ContentHandler::$enableDeprecationWarnings
1017          */
1018         public static function runLegacyHooks( $event, $args = array(),
1019                         $warn = null ) {
1020
1021                 if ( $warn === null ) {
1022                         $warn = self::$enableDeprecationWarnings;
1023                 }
1024
1025                 if ( !Hooks::isRegistered( $event ) ) {
1026                         return true; // nothing to do here
1027                 }
1028
1029                 if ( $warn ) {
1030                         // Log information about which handlers are registered for the legacy hook,
1031                         // so we can find and fix them.
1032
1033                         $handlers = Hooks::getHandlers( $event );
1034                         $handlerInfo = array();
1035
1036                         wfSuppressWarnings();
1037
1038                         foreach ( $handlers as $handler ) {
1039                                 $info = '';
1040
1041                                 if ( is_array( $handler ) ) {
1042                                         if ( is_object( $handler[0] ) ) {
1043                                                 $info = get_class( $handler[0] );
1044                                         } else {
1045                                                 $info = $handler[0];
1046                                         }
1047
1048                                         if ( isset( $handler[1] ) ) {
1049                                                 $info .= '::' . $handler[1];
1050                                         }
1051                                 } else if ( is_object( $handler ) ) {
1052                                         $info = get_class( $handler[0] );
1053                                         $info .= '::on' . $event;
1054                                 } else {
1055                                         $info = $handler;
1056                                 }
1057
1058                                 $handlerInfo[] = $info;
1059                         }
1060
1061                         wfRestoreWarnings();
1062
1063                         wfWarn( "Using obsolete hook $event via ContentHandler::runLegacyHooks()! Handlers: " . implode(', ', $handlerInfo), 2 );
1064                 }
1065
1066                 // convert Content objects to text
1067                 $contentObjects = array();
1068                 $contentTexts = array();
1069
1070                 foreach ( $args as $k => $v ) {
1071                         if ( $v instanceof Content ) {
1072                                 /* @var Content $v */
1073
1074                                 $contentObjects[$k] = $v;
1075
1076                                 $v = $v->serialize();
1077                                 $contentTexts[ $k ] = $v;
1078                                 $args[ $k ] = $v;
1079                         }
1080                 }
1081
1082                 // call the hook functions
1083                 $ok = wfRunHooks( $event, $args );
1084
1085                 // see if the hook changed the text
1086                 foreach ( $contentTexts as $k => $orig ) {
1087                         /* @var Content $content */
1088
1089                         $modified = $args[ $k ];
1090                         $content = $contentObjects[$k];
1091
1092                         if ( $modified !== $orig ) {
1093                                 // text was changed, create updated Content object
1094                                 $content = $content->getContentHandler()->unserializeContent( $modified );
1095                         }
1096
1097                         $args[ $k ] = $content;
1098                 }
1099
1100                 return $ok;
1101         }
1102 }
1103
1104 /**
1105  * @since 1.21
1106  */
1107 class TextContentHandler extends ContentHandler {
1108
1109         public function __construct( $modelId = CONTENT_MODEL_TEXT, $formats = array( CONTENT_FORMAT_TEXT ) ) {
1110                 parent::__construct( $modelId, $formats );
1111         }
1112
1113         /**
1114          * Returns the content's text as-is.
1115          *
1116          * @param $content Content
1117          * @param $format string|null
1118          * @return mixed
1119          */
1120         public function serializeContent( Content $content, $format = null ) {
1121                 $this->checkFormat( $format );
1122                 return $content->getNativeData();
1123         }
1124
1125         /**
1126          * Attempts to merge differences between three versions. Returns a new
1127          * Content object for a clean merge and false for failure or a conflict.
1128          *
1129          * All three Content objects passed as parameters must have the same
1130          * content model.
1131          *
1132          * This text-based implementation uses wfMerge().
1133          *
1134          * @param $oldContent \Content|string  String
1135          * @param $myContent \Content|string   String
1136          * @param $yourContent \Content|string String
1137          *
1138          * @return Content|Bool
1139          */
1140         public function merge3( Content $oldContent, Content $myContent, Content $yourContent ) {
1141                 $this->checkModelID( $oldContent->getModel() );
1142                 $this->checkModelID( $myContent->getModel() );
1143                 $this->checkModelID( $yourContent->getModel() );
1144
1145                 $format = $this->getDefaultFormat();
1146
1147                 $old = $this->serializeContent( $oldContent, $format );
1148                 $mine = $this->serializeContent( $myContent, $format );
1149                 $yours = $this->serializeContent( $yourContent, $format );
1150
1151                 $ok = wfMerge( $old, $mine, $yours, $result );
1152
1153                 if ( !$ok ) {
1154                         return false;
1155                 }
1156
1157                 if ( !$result ) {
1158                         return $this->makeEmptyContent();
1159                 }
1160
1161                 $mergedContent = $this->unserializeContent( $result, $format );
1162                 return $mergedContent;
1163         }
1164
1165         /**
1166          * Unserializes a Content object of the type supported by this ContentHandler.
1167          *
1168          * @since 1.21
1169          *
1170          * @param $text   string serialized form of the content
1171          * @param $format null|String the format used for serialization
1172          *
1173          * @return Content the TextContent object wrapping $text
1174          */
1175         public function unserializeContent( $text, $format = null ) {
1176                 $this->checkFormat( $format );
1177
1178                 return new TextContent( $text );
1179         }
1180
1181         /**
1182          * Creates an empty TextContent object.
1183          *
1184          * @since 1.21
1185          *
1186          * @return Content
1187          */
1188         public function makeEmptyContent() {
1189                 return new TextContent( '' );
1190         }
1191 }
1192
1193 /**
1194  * @since 1.21
1195  */
1196 class WikitextContentHandler extends TextContentHandler {
1197
1198         public function __construct( $modelId = CONTENT_MODEL_WIKITEXT ) {
1199                 parent::__construct( $modelId, array( CONTENT_FORMAT_WIKITEXT ) );
1200         }
1201
1202         public function unserializeContent( $text, $format = null ) {
1203                 $this->checkFormat( $format );
1204
1205                 return new WikitextContent( $text );
1206         }
1207
1208         /**
1209          * @see ContentHandler::makeEmptyContent
1210          *
1211          * @return Content
1212          */
1213         public function makeEmptyContent() {
1214                 return new WikitextContent( '' );
1215         }
1216
1217
1218         /**
1219          * Returns a WikitextContent object representing a redirect to the given destination page.
1220          *
1221          * @see ContentHandler::makeRedirectContent
1222          *
1223          * @param Title $destination the page to redirect to.
1224          *
1225          * @return Content
1226          */
1227         public function makeRedirectContent( Title $destination ) {
1228                 $mwRedir = MagicWord::get( 'redirect' );
1229                 $redirectText = $mwRedir->getSynonym( 0 ) . ' [[' . $destination->getPrefixedText() . "]]\n";
1230
1231                 return new WikitextContent( $redirectText );
1232         }
1233
1234         /**
1235          * Returns true because wikitext supports sections.
1236          *
1237          * @return boolean whether sections are supported.
1238          */
1239         public function supportsSections() {
1240                 return true;
1241         }
1242
1243         /**
1244          * Returns true, because wikitext supports caching using the
1245          * ParserCache mechanism.
1246          *
1247          * @since 1.21
1248          * @return bool
1249          */
1250         public function isParserCacheSupported() {
1251                 return true;
1252         }
1253 }
1254
1255 # XXX: make ScriptContentHandler base class, do highlighting stuff there?
1256
1257 /**
1258  * @since 1.21
1259  */
1260 class JavaScriptContentHandler extends TextContentHandler {
1261
1262         public function __construct( $modelId = CONTENT_MODEL_JAVASCRIPT ) {
1263                 parent::__construct( $modelId, array( CONTENT_FORMAT_JAVASCRIPT ) );
1264         }
1265
1266         public function unserializeContent( $text, $format = null ) {
1267                 $this->checkFormat( $format );
1268
1269                 return new JavaScriptContent( $text );
1270         }
1271
1272         public function makeEmptyContent() {
1273                 return new JavaScriptContent( '' );
1274         }
1275
1276         /**
1277          * Returns the english language, because JS is english, and should be handled as such.
1278          *
1279          * @return Language wfGetLangObj( 'en' )
1280          *
1281          * @see ContentHandler::getPageLanguage()
1282          */
1283         public function getPageLanguage( Title $title, Content $content = null ) {
1284                 return wfGetLangObj( 'en' );
1285         }
1286
1287         /**
1288          * Returns the english language, because CSS is english, and should be handled as such.
1289          *
1290          * @return Language wfGetLangObj( 'en' )
1291          *
1292          * @see ContentHandler::getPageViewLanguage()
1293          */
1294         public function getPageViewLanguage( Title $title, Content $content = null ) {
1295                 return wfGetLangObj( 'en' );
1296         }
1297 }
1298
1299 /**
1300  * @since 1.21
1301  */
1302 class CssContentHandler extends TextContentHandler {
1303
1304         public function __construct( $modelId = CONTENT_MODEL_CSS ) {
1305                 parent::__construct( $modelId, array( CONTENT_FORMAT_CSS ) );
1306         }
1307
1308         public function unserializeContent( $text, $format = null ) {
1309                 $this->checkFormat( $format );
1310
1311                 return new CssContent( $text );
1312         }
1313
1314         public function makeEmptyContent() {
1315                 return new CssContent( '' );
1316         }
1317
1318         /**
1319          * Returns the english language, because CSS is english, and should be handled as such.
1320          *
1321          * @return Language wfGetLangObj( 'en' )
1322          *
1323          * @see ContentHandler::getPageLanguage()
1324          */
1325         public function getPageLanguage( Title $title, Content $content = null ) {
1326                 return wfGetLangObj( 'en' );
1327         }
1328
1329         /**
1330          * Returns the english language, because CSS is english, and should be handled as such.
1331          *
1332          * @return Language wfGetLangObj( 'en' )
1333          *
1334          * @see ContentHandler::getPageViewLanguage()
1335          */
1336         public function getPageViewLanguage( Title $title, Content $content = null ) {
1337                 return wfGetLangObj( 'en' );
1338         }
1339 }