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