includes/content/ContentHandler.php

   1 <?php
   2 /**
   3  * Base class for content handling.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @since 1.21
  21  *
  22  * @file
  23  * @ingroup Content
  24  *
  25  * @author Daniel Kinzler
  26  */
  27
  28 /**
  29  * Exception representing a failure to serialize or unserialize a content object.
  30  *
  31  * @ingroup Content
  32  */
  33 class MWContentSerializationException extends MWException {
  34 }
  35
  36 /**
  37  * Exception thrown when an unregistered content model is requested. This error
  38  * can be triggered by user input, so a separate exception class is provided so
  39  * callers can substitute a context-specific, internationalised error message.
  40  *
  41  * @ingroup Content
  42  * @since 1.27
  43  */
  44 class MWUnknownContentModelException extends MWException {
  45         /** @var string The name of the unknown content model */
  46         private $modelId;
  47
  48         /** @param string $modelId */
  49         function __construct( $modelId ) {
  50                 parent::__construct( "The content model '$modelId' is not registered on this wiki.\n" .
  51                         'See https://www.mediawiki.org/wiki/Content_handlers to find out which extensions ' .
  52                         'handle this content model.' );
  53                 $this->modelId = $modelId;
  54         }
  55
  56         /** @return string */
  57         public function getModelId() {
  58                 return $modelId;
  59         }
  60 }
  61
  62 /**
  63  * A content handler knows how do deal with a specific type of content on a wiki
  64  * page. Content is stored in the database in a serialized form (using a
  65  * serialization format a.k.a. MIME type) and is unserialized into its native
  66  * PHP representation (the content model), which is wrapped in an instance of
  67  * the appropriate subclass of Content.
  68  *
  69  * ContentHandler instances are stateless singletons that serve, among other
  70  * things, as a factory for Content objects. Generally, there is one subclass
  71  * of ContentHandler and one subclass of Content for every type of content model.
  72  *
  73  * Some content types have a flat model, that is, their native representation
  74  * is the same as their serialized form. Examples would be JavaScript and CSS
  75  * code. As of now, this also applies to wikitext (MediaWiki's default content
  76  * type), but wikitext content may be represented by a DOM or AST structure in
  77  * the future.
  78  *
  79  * @ingroup Content
  80  */
  81 abstract class ContentHandler {
  82         /**
  83          * Switch for enabling deprecation warnings. Used by ContentHandler::deprecated()
  84          * and ContentHandler::runLegacyHooks().
  85          *
  86          * Once the ContentHandler code has settled in a bit, this should be set to true to
  87          * make extensions etc. show warnings when using deprecated functions and hooks.
  88          */
  89         protected static $enableDeprecationWarnings = false;
  90
  91         /**
  92          * Convenience function for getting flat text from a Content object. This
  93          * should only be used in the context of backwards compatibility with code
  94          * that is not yet able to handle Content objects!
  95          *
  96          * If $content is null, this method returns the empty string.
  97          *
  98          * If $content is an instance of TextContent, this method returns the flat
  99          * text as returned by $content->getNativeData().
 100          *
 101          * If $content is not a TextContent object, the behavior of this method
 102          * depends on the global $wgContentHandlerTextFallback:
 103          * - If $wgContentHandlerTextFallback is 'fail' and $content is not a
 104          *   TextContent object, an MWException is thrown.
 105          * - If $wgContentHandlerTextFallback is 'serialize' and $content is not a
 106          *   TextContent object, $content->serialize() is called to get a string
 107          *   form of the content.
 108          * - If $wgContentHandlerTextFallback is 'ignore' and $content is not a
 109          *   TextContent object, this method returns null.
 110          * - otherwise, the behavior is undefined.
 111          *
 112          * @since 1.21
 113          *
 114          * @param Content $content
 115          *
 116          * @throws MWException If the content is not an instance of TextContent and
 117          * wgContentHandlerTextFallback was set to 'fail'.
 118          * @return string|null Textual form of the content, if available.
 119          */
 120         public static function getContentText( Content $content = null ) {
 121                 global $wgContentHandlerTextFallback;
 122
 123                 if ( is_null( $content ) ) {
 124                         return '';
 125                 }
 126
 127                 if ( $content instanceof TextContent ) {
 128                         return $content->getNativeData();
 129                 }
 130
 131                 wfDebugLog( 'ContentHandler', 'Accessing ' . $content->getModel() . ' content as text!' );
 132
 133                 if ( $wgContentHandlerTextFallback == 'fail' ) {
 134                         throw new MWException(
 135                                 "Attempt to get text from Content with model " .
 136                                 $content->getModel()
 137                         );
 138                 }
 139
 140                 if ( $wgContentHandlerTextFallback == 'serialize' ) {
 141                         return $content->serialize();
 142                 }
 143
 144                 return null;
 145         }
 146
 147         /**
 148          * Convenience function for creating a Content object from a given textual
 149          * representation.
 150          *
 151          * $text will be deserialized into a Content object of the model specified
 152          * by $modelId (or, if that is not given, $title->getContentModel()) using
 153          * the given format.
 154          *
 155          * @since 1.21
 156          *
 157          * @param string $text The textual representation, will be
 158          *    unserialized to create the Content object
 159          * @param Title $title The title of the page this text belongs to.
 160          *    Required if $modelId is not provided.
 161          * @param string $modelId The model to deserialize to. If not provided,
 162          *    $title->getContentModel() is used.
 163          * @param string $format The format to use for deserialization. If not
 164          *    given, the model's default format is used.
 165          *
 166          * @throws MWException If model ID or format is not supported or if the text can not be
 167          * unserialized using the format.
 168          * @return Content A Content object representing the text.
 169          */
 170         public static function makeContent( $text, Title $title = null,
 171                 $modelId = null, $format = null ) {
 172                 if ( is_null( $modelId ) ) {
 173                         if ( is_null( $title ) ) {
 174                                 throw new MWException( "Must provide a Title object or a content model ID." );
 175                         }
 176
 177                         $modelId = $title->getContentModel();
 178                 }
 179
 180                 $handler = ContentHandler::getForModelID( $modelId );
 181
 182                 return $handler->unserializeContent( $text, $format );
 183         }
 184
 185         /**
 186          * Returns the name of the default content model to be used for the page
 187          * with the given title.
 188          *
 189          * Note: There should rarely be need to call this method directly.
 190          * To determine the actual content model for a given page, use
 191          * Title::getContentModel().
 192          *
 193          * Which model is to be used by default for the page is determined based
 194          * on several factors:
 195          * - The global setting $wgNamespaceContentModels specifies a content model
 196          *   per namespace.
 197          * - The hook ContentHandlerDefaultModelFor may be used to override the page's default
 198          *   model.
 199          * - Pages in NS_MEDIAWIKI and NS_USER default to the CSS or JavaScript
 200          *   model if they end in .js or .css, respectively.
 201          * - Pages in NS_MEDIAWIKI default to the wikitext model otherwise.
 202          * - The hook TitleIsCssOrJsPage may be used to force a page to use the CSS
 203          *   or JavaScript model. This is a compatibility feature. The ContentHandlerDefaultModelFor
 204          *   hook should be used instead if possible.
 205          * - The hook TitleIsWikitextPage may be used to force a page to use the
 206          *   wikitext model. This is a compatibility feature. The ContentHandlerDefaultModelFor
 207          *   hook should be used instead if possible.
 208          *
 209          * If none of the above applies, the wikitext model is used.
 210          *
 211          * Note: this is used by, and may thus not use, Title::getContentModel()
 212          *
 213          * @since 1.21
 214          *
 215          * @param Title $title
 216          *
 217          * @return string Default model name for the page given by $title
 218          */
 219         public static function getDefaultModelFor( Title $title ) {
 220                 // NOTE: this method must not rely on $title->getContentModel() directly or indirectly,
 221                 //       because it is used to initialize the mContentModel member.
 222
 223                 $ns = $title->getNamespace();
 224
 225                 $ext = false;
 226                 $m = null;
 227                 $model = MWNamespace::getNamespaceContentModel( $ns );
 228
 229                 // Hook can determine default model
 230                 if ( !Hooks::run( 'ContentHandlerDefaultModelFor', array( $title, &$model ) ) ) {
 231                         if ( !is_null( $model ) ) {
 232                                 return $model;
 233                         }
 234                 }
 235
 236                 // Could this page contain code based on the title?
 237                 $isCodePage = NS_MEDIAWIKI == $ns && preg_match( '!\.(css|js|json)$!u', $title->getText(), $m );
 238                 if ( $isCodePage ) {
 239                         $ext = $m[1];
 240                 }
 241
 242                 // Hook can force JS/CSS
 243                 Hooks::run( 'TitleIsCssOrJsPage', array( $title, &$isCodePage ), '1.25' );
 244
 245                 // Is this a user subpage containing code?
 246                 $isCodeSubpage = NS_USER == $ns
 247                         && !$isCodePage
 248                         && preg_match( "/\\/.*\\.(js|css|json)$/", $title->getText(), $m );
 249                 if ( $isCodeSubpage ) {
 250                         $ext = $m[1];
 251                 }
 252
 253                 // Is this wikitext, according to $wgNamespaceContentModels or the DefaultModelFor hook?
 254                 $isWikitext = is_null( $model ) || $model == CONTENT_MODEL_WIKITEXT;
 255                 $isWikitext = $isWikitext && !$isCodePage && !$isCodeSubpage;
 256
 257                 // Hook can override $isWikitext
 258                 Hooks::run( 'TitleIsWikitextPage', array( $title, &$isWikitext ), '1.25' );
 259
 260                 if ( !$isWikitext ) {
 261                         switch ( $ext ) {
 262                                 case 'js':
 263                                         return CONTENT_MODEL_JAVASCRIPT;
 264                                 case 'css':
 265                                         return CONTENT_MODEL_CSS;
 266                                 case 'json':
 267                                         return CONTENT_MODEL_JSON;
 268                                 default:
 269                                         return is_null( $model ) ? CONTENT_MODEL_TEXT : $model;
 270                         }
 271                 }
 272
 273                 // We established that it must be wikitext
 274
 275                 return CONTENT_MODEL_WIKITEXT;
 276         }
 277
 278         /**
 279          * Returns the appropriate ContentHandler singleton for the given title.
 280          *
 281          * @since 1.21
 282          *
 283          * @param Title $title
 284          *
 285          * @return ContentHandler
 286          */
 287         public static function getForTitle( Title $title ) {
 288                 $modelId = $title->getContentModel();
 289
 290                 return ContentHandler::getForModelID( $modelId );
 291         }
 292
 293         /**
 294          * Returns the appropriate ContentHandler singleton for the given Content
 295          * object.
 296          *
 297          * @since 1.21
 298          *
 299          * @param Content $content
 300          *
 301          * @return ContentHandler
 302          */
 303         public static function getForContent( Content $content ) {
 304                 $modelId = $content->getModel();
 305
 306                 return ContentHandler::getForModelID( $modelId );
 307         }
 308
 309         /**
 310          * @var array A Cache of ContentHandler instances by model id
 311          */
 312         protected static $handlers;
 313
 314         /**
 315          * Returns the ContentHandler singleton for the given model ID. Use the
 316          * CONTENT_MODEL_XXX constants to identify the desired content model.
 317          *
 318          * ContentHandler singletons are taken from the global $wgContentHandlers
 319          * array. Keys in that array are model names, the values are either
 320          * ContentHandler singleton objects, or strings specifying the appropriate
 321          * subclass of ContentHandler.
 322          *
 323          * If a class name is encountered when looking up the singleton for a given
 324          * model name, the class is instantiated and the class name is replaced by
 325          * the resulting singleton in $wgContentHandlers.
 326          *
 327          * If no ContentHandler is defined for the desired $modelId, the
 328          * ContentHandler may be provided by the ContentHandlerForModelID hook.
 329          * If no ContentHandler can be determined, an MWException is raised.
 330          *
 331          * @since 1.21
 332          *
 333          * @param string $modelId The ID of the content model for which to get a
 334          *    handler. Use CONTENT_MODEL_XXX constants.
 335          *
 336          * @throws MWException For internal errors and problems in the configuration.
 337          * @throws MWUnknownContentModelException If no handler is known for the model ID.
 338          * @return ContentHandler The ContentHandler singleton for handling the model given by the ID.
 339          */
 340         public static function getForModelID( $modelId ) {
 341                 global $wgContentHandlers;
 342
 343                 if ( isset( ContentHandler::$handlers[$modelId] ) ) {
 344                         return ContentHandler::$handlers[$modelId];
 345                 }
 346
 347                 if ( empty( $wgContentHandlers[$modelId] ) ) {
 348                         $handler = null;
 349
 350                         Hooks::run( 'ContentHandlerForModelID', array( $modelId, &$handler ) );
 351
 352                         if ( $handler === null ) {
 353                                 throw new MWUnknownContentModelException( $modelId );
 354                         }
 355
 356                         if ( !( $handler instanceof ContentHandler ) ) {
 357                                 throw new MWException( "ContentHandlerForModelID must supply a ContentHandler instance" );
 358                         }
 359                 } else {
 360                         $class = $wgContentHandlers[$modelId];
 361                         $handler = new $class( $modelId );
 362
 363                         if ( !( $handler instanceof ContentHandler ) ) {
 364                                 throw new MWException( "$class from \$wgContentHandlers is not " .
 365                                         "compatible with ContentHandler" );
 366                         }
 367                 }
 368
 369                 wfDebugLog( 'ContentHandler', 'Created handler for ' . $modelId
 370                         . ': ' . get_class( $handler ) );
 371
 372                 ContentHandler::$handlers[$modelId] = $handler;
 373
 374                 return ContentHandler::$handlers[$modelId];
 375         }
 376
 377         /**
 378          * Returns the localized name for a given content model.
 379          *
 380          * Model names are localized using system messages. Message keys
 381          * have the form content-model-$name, where $name is getContentModelName( $id ).
 382          *
 383          * @param string $name The content model ID, as given by a CONTENT_MODEL_XXX
 384          *    constant or returned by Revision::getContentModel().
 385          * @param Language|null $lang The language to parse the message in (since 1.26)
 386          *
 387          * @throws MWException If the model ID isn't known.
 388          * @return string The content model's localized name.
 389          */
 390         public static function getLocalizedName( $name, Language $lang = null ) {
 391                 // Messages: content-model-wikitext, content-model-text,
 392                 // content-model-javascript, content-model-css
 393                 $key = "content-model-$name";
 394
 395                 $msg = wfMessage( $key );
 396                 if ( $lang ) {
 397                         $msg->inLanguage( $lang );
 398                 }
 399
 400                 return $msg->exists() ? $msg->plain() : $name;
 401         }
 402
 403         public static function getContentModels() {
 404                 global $wgContentHandlers;
 405
 406                 return array_keys( $wgContentHandlers );
 407         }
 408
 409         public static function getAllContentFormats() {
 410                 global $wgContentHandlers;
 411
 412                 $formats = array();
 413
 414                 foreach ( $wgContentHandlers as $model => $class ) {
 415                         $handler = ContentHandler::getForModelID( $model );
 416                         $formats = array_merge( $formats, $handler->getSupportedFormats() );
 417                 }
 418
 419                 $formats = array_unique( $formats );
 420
 421                 return $formats;
 422         }
 423
 424         // ------------------------------------------------------------------------
 425
 426         /**
 427          * @var string
 428          */
 429         protected $mModelID;
 430
 431         /**
 432          * @var string[]
 433          */
 434         protected $mSupportedFormats;
 435
 436         /**
 437          * Constructor, initializing the ContentHandler instance with its model ID
 438          * and a list of supported formats. Values for the parameters are typically
 439          * provided as literals by subclass's constructors.
 440          *
 441          * @param string $modelId (use CONTENT_MODEL_XXX constants).
 442          * @param string[] $formats List for supported serialization formats
 443          *    (typically as MIME types)
 444          */
 445         public function __construct( $modelId, $formats ) {
 446                 $this->mModelID = $modelId;
 447                 $this->mSupportedFormats = $formats;
 448
 449                 $this->mModelName = preg_replace( '/(Content)?Handler$/', '', get_class( $this ) );
 450                 $this->mModelName = preg_replace( '/[_\\\\]/', '', $this->mModelName );
 451                 $this->mModelName = strtolower( $this->mModelName );
 452         }
 453
 454         /**
 455          * Serializes a Content object of the type supported by this ContentHandler.
 456          *
 457          * @since 1.21
 458          *
 459          * @param Content $content The Content object to serialize
 460          * @param string $format The desired serialization format
 461          *
 462          * @return string Serialized form of the content
 463          */
 464         abstract public function serializeContent( Content $content, $format = null );
 465
 466         /**
 467          * Applies transformations on export (returns the blob unchanged per default).
 468          * Subclasses may override this to perform transformations such as conversion
 469          * of legacy formats or filtering of internal meta-data.
 470          *
 471          * @param string $blob The blob to be exported
 472          * @param string|null $format The blob's serialization format
 473          *
 474          * @return string
 475          */
 476         public function exportTransform( $blob, $format = null ) {
 477                 return $blob;
 478         }
 479
 480         /**
 481          * Unserializes a Content object of the type supported by this ContentHandler.
 482          *
 483          * @since 1.21
 484          *
 485          * @param string $blob Serialized form of the content
 486          * @param string $format The format used for serialization
 487          *
 488          * @return Content The Content object created by deserializing $blob
 489          */
 490         abstract public function unserializeContent( $blob, $format = null );
 491
 492         /**
 493          * Apply import transformation (per default, returns $blob unchanged).
 494          * This gives subclasses an opportunity to transform data blobs on import.
 495          *
 496          * @since 1.24
 497          *
 498          * @param string $blob
 499          * @param string|null $format
 500          *
 501          * @return string
 502          */
 503         public function importTransform( $blob, $format = null ) {
 504                 return $blob;
 505         }
 506
 507         /**
 508          * Creates an empty Content object of the type supported by this
 509          * ContentHandler.
 510          *
 511          * @since 1.21
 512          *
 513          * @return Content
 514          */
 515         abstract public function makeEmptyContent();
 516
 517         /**
 518          * Creates a new Content object that acts as a redirect to the given page,
 519          * or null if redirects are not supported by this content model.
 520          *
 521          * This default implementation always returns null. Subclasses supporting redirects
 522          * must override this method.
 523          *
 524          * Note that subclasses that override this method to return a Content object
 525          * should also override supportsRedirects() to return true.
 526          *
 527          * @since 1.21
 528          *
 529          * @param Title $destination The page to redirect to.
 530          * @param string $text Text to include in the redirect, if possible.
 531          *
 532          * @return Content Always null.
 533          */
 534         public function makeRedirectContent( Title $destination, $text = '' ) {
 535                 return null;
 536         }
 537
 538         /**
 539          * Returns the model id that identifies the content model this
 540          * ContentHandler can handle. Use with the CONTENT_MODEL_XXX constants.
 541          *
 542          * @since 1.21
 543          *
 544          * @return string The model ID
 545          */
 546         public function getModelID() {
 547                 return $this->mModelID;
 548         }
 549
 550         /**
 551          * @since 1.21
 552          *
 553          * @param string $model_id The model to check
 554          *
 555          * @throws MWException If the model ID is not the ID of the content model supported by this
 556          * ContentHandler.
 557          */
 558         protected function checkModelID( $model_id ) {
 559                 if ( $model_id !== $this->mModelID ) {
 560                         throw new MWException( "Bad content model: " .
 561                                 "expected {$this->mModelID} " .
 562                                 "but got $model_id." );
 563                 }
 564         }
 565
 566         /**
 567          * Returns a list of serialization formats supported by the
 568          * serializeContent() and unserializeContent() methods of this
 569          * ContentHandler.
 570          *
 571          * @since 1.21
 572          *
 573          * @return string[] List of serialization formats as MIME type like strings
 574          */
 575         public function getSupportedFormats() {
 576                 return $this->mSupportedFormats;
 577         }
 578
 579         /**
 580          * The format used for serialization/deserialization by default by this
 581          * ContentHandler.
 582          *
 583          * This default implementation will return the first element of the array
 584          * of formats that was passed to the constructor.
 585          *
 586          * @since 1.21
 587          *
 588          * @return string The name of the default serialization format as a MIME type
 589          */
 590         public function getDefaultFormat() {
 591                 return $this->mSupportedFormats[0];
 592         }
 593
 594         /**
 595          * Returns true if $format is a serialization format supported by this
 596          * ContentHandler, and false otherwise.
 597          *
 598          * Note that if $format is null, this method always returns true, because
 599          * null means "use the default format".
 600          *
 601          * @since 1.21
 602          *
 603          * @param string $format The serialization format to check
 604          *
 605          * @return bool
 606          */
 607         public function isSupportedFormat( $format ) {
 608                 if ( !$format ) {
 609                         return true; // this means "use the default"
 610                 }
 611
 612                 return in_array( $format, $this->mSupportedFormats );
 613         }
 614
 615         /**
 616          * Convenient for checking whether a format provided as a parameter is actually supported.
 617          *
 618          * @param string $format The serialization format to check
 619          *
 620          * @throws MWException If the format is not supported by this content handler.
 621          */
 622         protected function checkFormat( $format ) {
 623                 if ( !$this->isSupportedFormat( $format ) ) {
 624                         throw new MWException(
 625                                 "Format $format is not supported for content model "
 626                                 . $this->getModelID()
 627                         );
 628                 }
 629         }
 630
 631         /**
 632          * Returns overrides for action handlers.
 633          * Classes listed here will be used instead of the default one when
 634          * (and only when) $wgActions[$action] === true. This allows subclasses
 635          * to override the default action handlers.
 636          *
 637          * @since 1.21
 638          *
 639          * @return array Always an empty array.
 640          */
 641         public function getActionOverrides() {
 642                 return array();
 643         }
 644
 645         /**
 646          * Factory for creating an appropriate DifferenceEngine for this content model.
 647          *
 648          * @since 1.21
 649          *
 650          * @param IContextSource $context Context to use, anything else will be ignored.
 651          * @param int $old Revision ID we want to show and diff with.
 652          * @param int|string $new Either a revision ID or one of the strings 'cur', 'prev' or 'next'.
 653          * @param int $rcid FIXME: Deprecated, no longer used. Defaults to 0.
 654          * @param bool $refreshCache If set, refreshes the diff cache. Defaults to false.
 655          * @param bool $unhide If set, allow viewing deleted revs. Defaults to false.
 656          *
 657          * @return DifferenceEngine
 658          */
 659         public function createDifferenceEngine( IContextSource $context, $old = 0, $new = 0,
 660                 $rcid = 0, // FIXME: Deprecated, no longer used
 661                 $refreshCache = false, $unhide = false ) {
 662
 663                 // hook: get difference engine
 664                 $differenceEngine = null;
 665                 if ( !Hooks::run( 'GetDifferenceEngine',
 666                         array( $context, $old, $new, $refreshCache, $unhide, &$differenceEngine )
 667                 ) ) {
 668                         return $differenceEngine;
 669                 }
 670                 $diffEngineClass = $this->getDiffEngineClass();
 671                 return new $diffEngineClass( $context, $old, $new, $rcid, $refreshCache, $unhide );
 672         }
 673
 674         /**
 675          * Get the language in which the content of the given page is written.
 676          *
 677          * This default implementation just returns $wgContLang (except for pages
 678          * in the MediaWiki namespace)
 679          *
 680          * Note that the pages language is not cacheable, since it may in some
 681          * cases depend on user settings.
 682          *
 683          * Also note that the page language may or may not depend on the actual content of the page,
 684          * that is, this method may load the content in order to determine the language.
 685          *
 686          * @since 1.21
 687          *
 688          * @param Title $title The page to determine the language for.
 689          * @param Content $content The page's content, if you have it handy, to avoid reloading it.
 690          *
 691          * @return Language The page's language
 692          */
 693         public function getPageLanguage( Title $title, Content $content = null ) {
 694                 global $wgContLang, $wgLang;
 695                 $pageLang = $wgContLang;
 696
 697                 if ( $title->getNamespace() == NS_MEDIAWIKI ) {
 698                         // Parse mediawiki messages with correct target language
 699                         list( /* $unused */, $lang ) = MessageCache::singleton()->figureMessage( $title->getText() );
 700                         $pageLang = wfGetLangObj( $lang );
 701                 }
 702
 703                 Hooks::run( 'PageContentLanguage', array( $title, &$pageLang, $wgLang ) );
 704
 705                 return wfGetLangObj( $pageLang );
 706         }
 707
 708         /**
 709          * Get the language in which the content of this page is written when
 710          * viewed by user. Defaults to $this->getPageLanguage(), but if the user
 711          * specified a preferred variant, the variant will be used.
 712          *
 713          * This default implementation just returns $this->getPageLanguage( $title, $content ) unless
 714          * the user specified a preferred variant.
 715          *
 716          * Note that the pages view language is not cacheable, since it depends on user settings.
 717          *
 718          * Also note that the page language may or may not depend on the actual content of the page,
 719          * that is, this method may load the content in order to determine the language.
 720          *
 721          * @since 1.21
 722          *
 723          * @param Title $title The page to determine the language for.
 724          * @param Content $content The page's content, if you have it handy, to avoid reloading it.
 725          *
 726          * @return Language The page's language for viewing
 727          */
 728         public function getPageViewLanguage( Title $title, Content $content = null ) {
 729                 $pageLang = $this->getPageLanguage( $title, $content );
 730
 731                 if ( $title->getNamespace() !== NS_MEDIAWIKI ) {
 732                         // If the user chooses a variant, the content is actually
 733                         // in a language whose code is the variant code.
 734                         $variant = $pageLang->getPreferredVariant();
 735                         if ( $pageLang->getCode() !== $variant ) {
 736                                 $pageLang = Language::factory( $variant );
 737                         }
 738                 }
 739
 740                 return $pageLang;
 741         }
 742
 743         /**
 744          * Determines whether the content type handled by this ContentHandler
 745          * can be used on the given page.
 746          *
 747          * This default implementation always returns true.
 748          * Subclasses may override this to restrict the use of this content model to specific locations,
 749          * typically based on the namespace or some other aspect of the title, such as a special suffix
 750          * (e.g. ".svg" for SVG content).
 751          *
 752          * @note this calls the ContentHandlerCanBeUsedOn hook which may be used to override which
 753          * content model can be used where.
 754          *
 755          * @param Title $title The page's title.
 756          *
 757          * @return bool True if content of this kind can be used on the given page, false otherwise.
 758          */
 759         public function canBeUsedOn( Title $title ) {
 760                 $ok = true;
 761
 762                 Hooks::run( 'ContentModelCanBeUsedOn', array( $this->getModelID(), $title, &$ok ) );
 763
 764                 return $ok;
 765         }
 766
 767         /**
 768          * Returns the name of the diff engine to use.
 769          *
 770          * @since 1.21
 771          *
 772          * @return string
 773          */
 774         protected function getDiffEngineClass() {
 775                 return 'DifferenceEngine';
 776         }
 777
 778         /**
 779          * Attempts to merge differences between three versions. Returns a new
 780          * Content object for a clean merge and false for failure or a conflict.
 781          *
 782          * This default implementation always returns false.
 783          *
 784          * @since 1.21
 785          *
 786          * @param Content $oldContent The page's previous content.
 787          * @param Content $myContent One of the page's conflicting contents.
 788          * @param Content $yourContent One of the page's conflicting contents.
 789          *
 790          * @return Content|bool Always false.
 791          */
 792         public function merge3( Content $oldContent, Content $myContent, Content $yourContent ) {
 793                 return false;
 794         }
 795
 796         /**
 797          * Return an applicable auto-summary if one exists for the given edit.
 798          *
 799          * @since 1.21
 800          *
 801          * @param Content $oldContent The previous text of the page.
 802          * @param Content $newContent The submitted text of the page.
 803          * @param int $flags Bit mask: a bit mask of flags submitted for the edit.
 804          *
 805          * @return string An appropriate auto-summary, or an empty string.
 806          */
 807         public function getAutosummary( Content $oldContent = null, Content $newContent = null,
 808                 $flags ) {
 809                 // Decide what kind of auto-summary is needed.
 810
 811                 // Redirect auto-summaries
 812
 813                 /**
 814                  * @var $ot Title
 815                  * @var $rt Title
 816                  */
 817
 818                 $ot = !is_null( $oldContent ) ? $oldContent->getRedirectTarget() : null;
 819                 $rt = !is_null( $newContent ) ? $newContent->getRedirectTarget() : null;
 820
 821                 if ( is_object( $rt ) ) {
 822                         if ( !is_object( $ot )
 823                                 || !$rt->equals( $ot )
 824                                 || $ot->getFragment() != $rt->getFragment()
 825                         ) {
 826                                 $truncatedtext = $newContent->getTextForSummary(
 827                                         250
 828                                         - strlen( wfMessage( 'autoredircomment' )->inContentLanguage()->text() )
 829                                         - strlen( $rt->getFullText() ) );
 830
 831                                 return wfMessage( 'autoredircomment', $rt->getFullText() )
 832                                         ->rawParams( $truncatedtext )->inContentLanguage()->text();
 833                         }
 834                 }
 835
 836                 // New page auto-summaries
 837                 if ( $flags & EDIT_NEW && $newContent->getSize() > 0 ) {
 838                         // If they're making a new article, give its text, truncated, in
 839                         // the summary.
 840
 841                         $truncatedtext = $newContent->getTextForSummary(
 842                                 200 - strlen( wfMessage( 'autosumm-new' )->inContentLanguage()->text() ) );
 843
 844                         return wfMessage( 'autosumm-new' )->rawParams( $truncatedtext )
 845                                 ->inContentLanguage()->text();
 846                 }
 847
 848                 // Blanking auto-summaries
 849                 if ( !empty( $oldContent ) && $oldContent->getSize() > 0 && $newContent->getSize() == 0 ) {
 850                         return wfMessage( 'autosumm-blank' )->inContentLanguage()->text();
 851                 } elseif ( !empty( $oldContent )
 852                         && $oldContent->getSize() > 10 * $newContent->getSize()
 853                         && $newContent->getSize() < 500
 854                 ) {
 855                         // Removing more than 90% of the article
 856
 857                         $truncatedtext = $newContent->getTextForSummary(
 858                                 200 - strlen( wfMessage( 'autosumm-replace' )->inContentLanguage()->text() ) );
 859
 860                         return wfMessage( 'autosumm-replace' )->rawParams( $truncatedtext )
 861                                 ->inContentLanguage()->text();
 862                 }
 863
 864                 // New blank article auto-summary
 865                 if ( $flags & EDIT_NEW && $newContent->isEmpty() ) {
 866                         return wfMessage( 'autosumm-newblank' )->inContentLanguage()->text();
 867                 }
 868
 869                 // If we reach this point, there's no applicable auto-summary for our
 870                 // case, so our auto-summary is empty.
 871                 return '';
 872         }
 873
 874         /**
 875          * Auto-generates a deletion reason
 876          *
 877          * @since 1.21
 878          *
 879          * @param Title $title The page's title
 880          * @param bool &$hasHistory Whether the page has a history
 881          *
 882          * @return mixed String containing deletion reason or empty string, or
 883          *    boolean false if no revision occurred
 884          *
 885          * @todo &$hasHistory is extremely ugly, it's here because
 886          * WikiPage::getAutoDeleteReason() and Article::generateReason()
 887          * have it / want it.
 888          */
 889         public function getAutoDeleteReason( Title $title, &$hasHistory ) {
 890                 $dbw = wfGetDB( DB_MASTER );
 891
 892                 // Get the last revision
 893                 $rev = Revision::newFromTitle( $title );
 894
 895                 if ( is_null( $rev ) ) {
 896                         return false;
 897                 }
 898
 899                 // Get the article's contents
 900                 $content = $rev->getContent();
 901                 $blank = false;
 902
 903                 // If the page is blank, use the text from the previous revision,
 904                 // which can only be blank if there's a move/import/protect dummy
 905                 // revision involved
 906                 if ( !$content || $content->isEmpty() ) {
 907                         $prev = $rev->getPrevious();
 908
 909                         if ( $prev ) {
 910                                 $rev = $prev;
 911                                 $content = $rev->getContent();
 912                                 $blank = true;
 913                         }
 914                 }
 915
 916                 $this->checkModelID( $rev->getContentModel() );
 917
 918                 // Find out if there was only one contributor
 919                 // Only scan the last 20 revisions
 920                 $res = $dbw->select( 'revision', 'rev_user_text',
 921                         array(
 922                                 'rev_page' => $title->getArticleID(),
 923                                 $dbw->bitAnd( 'rev_deleted', Revision::DELETED_USER ) . ' = 0'
 924                         ),
 925                         __METHOD__,
 926                         array( 'LIMIT' => 20 )
 927                 );
 928
 929                 if ( $res === false ) {
 930                         // This page has no revisions, which is very weird
 931                         return false;
 932                 }
 933
 934                 $hasHistory = ( $res->numRows() > 1 );
 935                 $row = $dbw->fetchObject( $res );
 936
 937                 if ( $row ) { // $row is false if the only contributor is hidden
 938                         $onlyAuthor = $row->rev_user_text;
 939                         // Try to find a second contributor
 940                         foreach ( $res as $row ) {
 941                                 if ( $row->rev_user_text != $onlyAuthor ) { // Bug 22999
 942                                         $onlyAuthor = false;
 943                                         break;
 944                                 }
 945                         }
 946                 } else {
 947                         $onlyAuthor = false;
 948                 }
 949
 950                 // Generate the summary with a '$1' placeholder
 951                 if ( $blank ) {
 952                         // The current revision is blank and the one before is also
 953                         // blank. It's just not our lucky day
 954                         $reason = wfMessage( 'exbeforeblank', '$1' )->inContentLanguage()->text();
 955                 } else {
 956                         if ( $onlyAuthor ) {
 957                                 $reason = wfMessage(
 958                                         'excontentauthor',
 959                                         '$1',
 960                                         $onlyAuthor
 961                                 )->inContentLanguage()->text();
 962                         } else {
 963                                 $reason = wfMessage( 'excontent', '$1' )->inContentLanguage()->text();
 964                         }
 965                 }
 966
 967                 if ( $reason == '-' ) {
 968                         // Allow these UI messages to be blanked out cleanly
 969                         return '';
 970                 }
 971
 972                 // Max content length = max comment length - length of the comment (excl. $1)
 973                 $text = $content ? $content->getTextForSummary( 255 - ( strlen( $reason ) - 2 ) ) : '';
 974
 975                 // Now replace the '$1' placeholder
 976                 $reason = str_replace( '$1', $text, $reason );
 977
 978                 return $reason;
 979         }
 980
 981         /**
 982          * Get the Content object that needs to be saved in order to undo all revisions
 983          * between $undo and $undoafter. Revisions must belong to the same page,
 984          * must exist and must not be deleted.
 985          *
 986          * @since 1.21
 987          *
 988          * @param Revision $current The current text
 989          * @param Revision $undo The revision to undo
 990          * @param Revision $undoafter Must be an earlier revision than $undo
 991          *
 992          * @return mixed String on success, false on failure
 993          */
 994         public function getUndoContent( Revision $current, Revision $undo, Revision $undoafter ) {
 995                 $cur_content = $current->getContent();
 996
 997                 if ( empty( $cur_content ) ) {
 998                         return false; // no page
 999                 }
1000
1001                 $undo_content = $undo->getContent();
1002                 $undoafter_content = $undoafter->getContent();
1003
1004                 if ( !$undo_content || !$undoafter_content ) {
1005                         return false; // no content to undo
1006                 }
1007
1008                 $this->checkModelID( $cur_content->getModel() );
1009                 $this->checkModelID( $undo_content->getModel() );
1010                 $this->checkModelID( $undoafter_content->getModel() );
1011
1012                 if ( $cur_content->equals( $undo_content ) ) {
1013                         // No use doing a merge if it's just a straight revert.
1014                         return $undoafter_content;
1015                 }
1016
1017                 $undone_content = $this->merge3( $undo_content, $undoafter_content, $cur_content );
1018
1019                 return $undone_content;
1020         }
1021
1022         /**
1023          * Get parser options suitable for rendering and caching the article
1024          *
1025          * @param IContextSource|User|string $context One of the following:
1026          *        - IContextSource: Use the User and the Language of the provided
1027          *                                            context
1028          *        - User: Use the provided User object and $wgLang for the language,
1029          *                                            so use an IContextSource object if possible.
1030          *        - 'canonical': Canonical options (anonymous user with default
1031          *                                            preferences and content language).
1032          *
1033          * @throws MWException
1034          * @return ParserOptions
1035          */
1036         public function makeParserOptions( $context ) {
1037                 global $wgContLang, $wgEnableParserLimitReporting;
1038
1039                 if ( $context instanceof IContextSource ) {
1040                         $options = ParserOptions::newFromContext( $context );
1041                 } elseif ( $context instanceof User ) { // settings per user (even anons)
1042                         $options = ParserOptions::newFromUser( $context );
1043                 } elseif ( $context === 'canonical' ) { // canonical settings
1044                         $options = ParserOptions::newFromUserAndLang( new User, $wgContLang );
1045                 } else {
1046                         throw new MWException( "Bad context for parser options: $context" );
1047                 }
1048
1049                 $options->enableLimitReport( $wgEnableParserLimitReporting ); // show inclusion/loop reports
1050                 $options->setTidy( true ); // fix bad HTML
1051
1052                 return $options;
1053         }
1054
1055         /**
1056          * Returns true for content models that support caching using the
1057          * ParserCache mechanism. See WikiPage::shouldCheckParserCache().
1058          *
1059          * @since 1.21
1060          *
1061          * @return bool Always false.
1062          */
1063         public function isParserCacheSupported() {
1064                 return false;
1065         }
1066
1067         /**
1068          * Returns true if this content model supports sections.
1069          * This default implementation returns false.
1070          *
1071          * Content models that return true here should also implement
1072          * Content::getSection, Content::replaceSection, etc. to handle sections..
1073          *
1074          * @return bool Always false.
1075          */
1076         public function supportsSections() {
1077                 return false;
1078         }
1079
1080         /**
1081          * Returns true if this content model supports redirects.
1082          * This default implementation returns false.
1083          *
1084          * Content models that return true here should also implement
1085          * ContentHandler::makeRedirectContent to return a Content object.
1086          *
1087          * @return bool Always false.
1088          */
1089         public function supportsRedirects() {
1090                 return false;
1091         }
1092
1093         /**
1094          * Return true if this content model supports direct editing, such as via EditPage.
1095          *
1096          * @return bool Default is false, and true for TextContent and it's derivatives.
1097          */
1098         public function supportsDirectEditing() {
1099                 return false;
1100         }
1101
1102         /**
1103          * Whether or not this content model supports direct editing via ApiEditPage
1104          *
1105          * @return bool Default is false, and true for TextContent and derivatives.
1106          */
1107         public function supportsDirectApiEditing() {
1108                 return $this->supportsDirectEditing();
1109         }
1110
1111         /**
1112          * Logs a deprecation warning, visible if $wgDevelopmentWarnings, but only if
1113          * self::$enableDeprecationWarnings is set to true.
1114          *
1115          * @param string $func The name of the deprecated function
1116          * @param string $version The version since the method is deprecated. Usually 1.21
1117          *   for ContentHandler related stuff.
1118          * @param string|bool $component : Component to which the function belongs.
1119          *   If false, it is assumed the function is in MediaWiki core.
1120          *
1121          * @see ContentHandler::$enableDeprecationWarnings
1122          * @see wfDeprecated
1123          */
1124         public static function deprecated( $func, $version, $component = false ) {
1125                 if ( self::$enableDeprecationWarnings ) {
1126                         wfDeprecated( $func, $version, $component, 3 );
1127                 }
1128         }
1129
1130         /**
1131          * Call a legacy hook that uses text instead of Content objects.
1132          * Will log a warning when a matching hook function is registered.
1133          * If the textual representation of the content is changed by the
1134          * hook function, a new Content object is constructed from the new
1135          * text.
1136          *
1137          * @param string $event Event name
1138          * @param array $args Parameters passed to hook functions
1139          * @param bool $warn Whether to log a warning.
1140          *                    Default to self::$enableDeprecationWarnings.
1141          *                    May be set to false for testing.
1142          *
1143          * @return bool True if no handler aborted the hook
1144          *
1145          * @see ContentHandler::$enableDeprecationWarnings
1146          */
1147         public static function runLegacyHooks( $event, $args = array(),
1148                 $warn = null
1149         ) {
1150
1151                 if ( $warn === null ) {
1152                         $warn = self::$enableDeprecationWarnings;
1153                 }
1154
1155                 if ( !Hooks::isRegistered( $event ) ) {
1156                         return true; // nothing to do here
1157                 }
1158
1159                 if ( $warn ) {
1160                         // Log information about which handlers are registered for the legacy hook,
1161                         // so we can find and fix them.
1162
1163                         $handlers = Hooks::getHandlers( $event );
1164                         $handlerInfo = array();
1165
1166                         MediaWiki\suppressWarnings();
1167
1168                         foreach ( $handlers as $handler ) {
1169                                 if ( is_array( $handler ) ) {
1170                                         if ( is_object( $handler[0] ) ) {
1171                                                 $info = get_class( $handler[0] );
1172                                         } else {
1173                                                 $info = $handler[0];
1174                                         }
1175
1176                                         if ( isset( $handler[1] ) ) {
1177                                                 $info .= '::' . $handler[1];
1178                                         }
1179                                 } elseif ( is_object( $handler ) ) {
1180                                         $info = get_class( $handler[0] );
1181                                         $info .= '::on' . $event;
1182                                 } else {
1183                                         $info = $handler;
1184                                 }
1185
1186                                 $handlerInfo[] = $info;
1187                         }
1188
1189                         MediaWiki\restoreWarnings();
1190
1191                         wfWarn( "Using obsolete hook $event via ContentHandler::runLegacyHooks()! Handlers: " .
1192                                 implode( ', ', $handlerInfo ), 2 );
1193                 }
1194
1195                 // convert Content objects to text
1196                 $contentObjects = array();
1197                 $contentTexts = array();
1198
1199                 foreach ( $args as $k => $v ) {
1200                         if ( $v instanceof Content ) {
1201                                 /* @var Content $v */
1202
1203                                 $contentObjects[$k] = $v;
1204
1205                                 $v = $v->serialize();
1206                                 $contentTexts[$k] = $v;
1207                                 $args[$k] = $v;
1208                         }
1209                 }
1210
1211                 // call the hook functions
1212                 $ok = Hooks::run( $event, $args );
1213
1214                 // see if the hook changed the text
1215                 foreach ( $contentTexts as $k => $orig ) {
1216                         /* @var Content $content */
1217
1218                         $modified = $args[$k];
1219                         $content = $contentObjects[$k];
1220
1221                         if ( $modified !== $orig ) {
1222                                 // text was changed, create updated Content object
1223                                 $content = $content->getContentHandler()->unserializeContent( $modified );
1224                         }
1225
1226                         $args[$k] = $content;
1227                 }
1228
1229                 return $ok;
1230         }
1231 }