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