includes/ContentHandler.php

   1 <?php
   2
   3 class MWContentSerializationException extends MWException {
   4
   5 }
   6
   7
   8 /**
   9  * A content handler knows how do deal with a specific type of content on a wiki page.
  10  * Content is stored in the database in a serialized form (using a serialization format aka mime type)
  11  * and is be unserialized into it's native PHP represenation (the content model), which is wrappe in
  12  * an instance of the appropriate subclass of Content.
  13  *
  14  * ContentHandler instances are stateless singletons that serve, among other things, as a factory for
  15  * Content objects. Generally, there is one subclass of ContentHandler and one subclass of Content
  16  * for every type of content model.
  17  *
  18  * Some content types have a flat model, that is, their native represenation is the
  19  * same as their serialized form. Examples would be JavaScript and CSS code. As of now,
  20  * this also applies to wikitext (mediawiki's default content type), but wikitext
  21  * content may be represented by a DOM or AST structure in the future.
  22  *
  23  * @since 1.WD
  24  */
  25 abstract class ContentHandler {
  26
  27         /**
  28          * Conveniance function for getting flat text from a Content object. This should only
  29          * be used in the context of backwards compatibility with code that is not yet able
  30          * to handle Content objects!
  31          *
  32          * If $content is null, this method returns the empty string.
  33          *
  34          * If $content is an instance of TextContent, this method returns the flat text as returned by $content->getNativeData().
  35          *
  36          * If $content is not a TextContent object, the bahaviour of this method depends on the global $wgContentHandlerTextFallback:
  37          * * If $wgContentHandlerTextFallback is 'fail' and $content is not a TextContent object, an MWException is thrown.
  38          * * If $wgContentHandlerTextFallback is 'serialize' and $content is not a TextContent object, $content->serialize()
  39          * is called to get a string form of the content.
  40          * * If $wgContentHandlerTextFallback is 'ignore' and $content is not a TextContent object, this method returns null.
  41          * * otherwise, the behaviour is undefined.
  42          *
  43          * @since WD.1
  44          *
  45          * @static
  46          * @param Content|null $content
  47          * @return null|string the textual form of $content, if available
  48          * @throws MWException if $content is not an instance of TextContent and $wgContentHandlerTextFallback was set to 'fail'.
  49          */
  50         public static function getContentText( Content $content = null ) {
  51                 global $wgContentHandlerTextFallback;
  52
  53                 if ( is_null( $content ) ) {
  54                         return '';
  55                 }
  56
  57                 if ( $content instanceof TextContent ) {
  58                         return $content->getNativeData();
  59                 }
  60
  61                 if ( $wgContentHandlerTextFallback == 'fail' ) {
  62                         throw new MWException( "Attempt to get text from Content with model " . $content->getModel() );
  63                 }
  64
  65                 if ( $wgContentHandlerTextFallback == 'serialize' ) {
  66                         return $content->serialize();
  67                 }
  68
  69                 return null;
  70         }
  71
  72         /**
  73          * Conveniance function for creating a Content object from a given textual representation.
  74          *
  75          * $text will be deserialized into a Content object of the model specified by $modelId (or,
  76          * if that is not given, $title->getContentModel()) using the given format.
  77          *
  78          * @since WD.1
  79          *
  80          * @static
  81          * @param string $text the textual represenation, will be unserialized to create the Content object
  82          * @param Title $title the title of the page this text belongs to, required as a context for deserialization
  83          * @param null|String $modelId the model to deserialize to. If not provided, $title->getContentModel() is used.
  84          * @param null|String $format the format to use for deserialization. If not given, the model's default format is used.
  85          *
  86          * @return Content a Content object representing $text
  87          * @throw MWException if $model or $format is not supported or if $text can not be unserialized using $format.
  88          */
  89         public static function makeContent( $text, Title $title, $modelId = null, $format = null ) {
  90
  91                 if ( is_null( $modelId ) ) {
  92                         $modelId = $title->getContentModel();
  93                 }
  94
  95                 $handler = ContentHandler::getForModelID( $modelId );
  96                 return $handler->unserializeContent( $text, $format );
  97         }
  98
  99         /**
 100          * Returns the name of the default content model to be used for the page with the given title.
 101          *
 102          * Note: There should rarely be need to call this method directly.
 103          * To determine the actual content model for a given page, use Title::getContentModel().
 104          *
 105          * Which model is to be used per default for the page is determined based on several factors:
 106          * * The global setting $wgNamespaceContentModels specifies a content model per namespace.
 107          * * The hook DefaultModelFor may be used to override the page's default model.
 108          * * Pages in NS_MEDIAWIKI and NS_USER default to the CSS or JavaScript model if they end in .js or .css, respectively.
 109          * * Pages in NS_MEDIAWIKI default to the wikitext model otherwise.
 110          * * The hook TitleIsCssOrJsPage may be used to force a page to use the CSS or JavaScript model if they end in .js or .css, respectively.
 111          * * The hook TitleIsWikitextPage may be used to force a page to use the wikitext model.
 112          *
 113          * If none of the above applies, the wikitext model is used.
 114          *
 115          * Note: this is used by, and may thus not use, Title::getContentModel()
 116          *
 117          * @since WD.1
 118          *
 119          * @static
 120          * @param Title $title
 121          * @return null|string default model name for the page given by $title
 122          */
 123         public static function getDefaultModelFor( Title $title ) {
 124                 global $wgNamespaceContentModels;
 125
 126                 // NOTE: this method must not rely on $title->getContentModel() directly or indirectly,
 127                 //       because it is used to initialized the mContentModel memebr.
 128
 129                 $ns = $title->getNamespace();
 130
 131                 $ext = false;
 132                 $m = null;
 133                 $model = null;
 134
 135                 if ( !empty( $wgNamespaceContentModels[ $ns ] ) ) {
 136                         $model = $wgNamespaceContentModels[ $ns ];
 137                 }
 138
 139                 // hook can determin default model
 140                 if ( !wfRunHooks( 'ContentHandlerDefaultModelFor', array( $title, &$model ) ) ) {
 141                         if ( !is_null( $model ) ) {
 142                                 return $model;
 143                         }
 144                 }
 145
 146                 // Could this page contain custom CSS or JavaScript, based on the title?
 147                 $isCssOrJsPage = NS_MEDIAWIKI == $ns && preg_match( '!\.(css|js)$!u', $title->getText(), $m );
 148                 if ( $isCssOrJsPage ) {
 149                         $ext = $m[1];
 150                 }
 151
 152                 // hook can force js/css
 153                 wfRunHooks( 'TitleIsCssOrJsPage', array( $title, &$isCssOrJsPage ) );
 154
 155                 // Is this a .css subpage of a user page?
 156                 $isJsCssSubpage = NS_USER == $ns && !$isCssOrJsPage && preg_match( "/\\/.*\\.(js|css)$/", $title->getText(), $m );
 157                 if ( $isJsCssSubpage ) {
 158                         $ext = $m[1];
 159                 }
 160
 161                 // is this wikitext, according to $wgNamespaceContentModels or the DefaultModelFor hook?
 162                 $isWikitext = is_null( $model ) || $model == CONTENT_MODEL_WIKITEXT;
 163                 $isWikitext = $isWikitext && !$isCssOrJsPage && !$isJsCssSubpage;
 164
 165                 // hook can override $isWikitext
 166                 wfRunHooks( 'TitleIsWikitextPage', array( $title, &$isWikitext ) );
 167
 168                 if ( !$isWikitext ) {
 169                         switch ( $ext ) {
 170                                 case 'js':
 171                                         return CONTENT_MODEL_JAVASCRIPT;
 172                                 case 'css':
 173                                         return CONTENT_MODEL_CSS;
 174                                 default:
 175                                         return is_null( $model ) ? CONTENT_MODEL_TEXT : $model;
 176                         }
 177                 }
 178
 179                 // we established that is must be wikitext
 180
 181                 return CONTENT_MODEL_WIKITEXT;
 182         }
 183
 184         /**
 185          * returns the appropriate ContentHandler singleton for the given title
 186          *
 187          * @since WD.1
 188          *
 189          * @static
 190          * @param Title $title
 191          * @return ContentHandler
 192          */
 193         public static function getForTitle( Title $title ) {
 194                 $modelId = $title->getContentModel();
 195                 return ContentHandler::getForModelID( $modelId );
 196         }
 197
 198         /**
 199          * returns the appropriate ContentHandler singleton for the given Content object
 200          *
 201          * @since WD.1
 202          *
 203          * @static
 204          * @param Content $content
 205          * @return ContentHandler
 206          */
 207         public static function getForContent( Content $content ) {
 208                 $modelId = $content->getModel();
 209                 return ContentHandler::getForModelID( $modelId );
 210         }
 211
 212         /**
 213          * returns the ContentHandler singleton for the given model id. Use the CONTENT_MODEL_XXX constants to
 214          * identify the desired content model.
 215          *
 216          * ContentHandler singletons are take from the global $wgContentHandlers array. Keys in that array are
 217          * model names, the values are either ContentHandler singleton objects, or strings specifying the appropriate
 218          * subclass of ContentHandler.
 219          *
 220          * If a class name in encountered when looking up the singleton for a given model name, the class is
 221          * instantiated and the class name is replaced by te resulting singleton in $wgContentHandlers.
 222          *
 223          * If no ContentHandler is defined for the desired $modelId, the ContentHandler may be provided by the
 224          * a ContentHandlerForModelID hook. if no Contenthandler can be determined, an MWException is raised.
 225          *
 226          * @since WD.1
 227          *
 228          * @static
 229          * @param $modelId int the id of the content model for which to get a handler. Use CONTENT_MODEL_XXX constants.
 230          * @return ContentHandler the ContentHandler singleton for handling the model given by $modelId
 231          * @throws MWException if no handler is known for $modelId.
 232          */
 233         public static function getForModelID( $modelId ) {
 234                 global $wgContentHandlers;
 235
 236                 if ( empty( $wgContentHandlers[$modelId] ) ) {
 237                         $handler = null;
 238
 239                         wfRunHooks( 'ContentHandlerForModelID', array( $modelId, &$handler ) );
 240
 241                         if ( $handler ) { // NOTE: may be a string or an object, either is fine!
 242                                 $wgContentHandlers[$modelId] = $handler;
 243                         } else {
 244                                 throw new MWException( "No handler for model #$modelId registered in \$wgContentHandlers" );
 245                         }
 246                 }
 247
 248                 if ( is_string( $wgContentHandlers[$modelId] ) ) {
 249                         $class = $wgContentHandlers[$modelId];
 250                         $wgContentHandlers[$modelId] = new $class( $modelId );
 251                 }
 252
 253                 return $wgContentHandlers[$modelId];
 254         }
 255
 256         /**
 257          * Returns the appropriate mime type for a given content format,
 258          * or null if no mime type is known for this format.
 259          *
 260          * Mime types can be registered in the global array $wgContentFormatMimeTypes.
 261          *
 262          * @static
 263          * @param int $id the content format id, as given by a CONTENT_FORMAT_XXX constant
 264          *        or returned by Revision::getContentFormat().
 265          *
 266          * @return String|null the content format's mime type.
 267          */
 268         public static function getContentFormatMimeType( $id ) {
 269                 global $wgContentFormatMimeTypes;
 270
 271                 if ( !isset( $wgContentFormatMimeTypes[ $id ] ) ) {
 272                         return null;
 273                 }
 274
 275                 return $wgContentFormatMimeTypes[ $id ];
 276         }
 277
 278         /**
 279          * Returns the content format if for a given mime type,
 280          * or null if no format id if known for this mime type.
 281          *
 282          * Mime types can be registered in the global array $wgContentFormatMimeTypes.
 283          *
 284          * @static
 285          * @param String $mime the mime type
 286          *
 287          * @return int|null the format id, as defined by a CONTENT_FORMAT_XXX constant
 288          */
 289         public static function getContentFormatID( $mime ) {
 290                 global $wgContentFormatMimeTypes;
 291
 292                 static $format_ids = null;
 293
 294                 if ( $format_ids === null ) {
 295                         $format_ids = array_flip( $wgContentFormatMimeTypes );
 296                 }
 297
 298                 if ( !isset( $format_ids[ $mime ] ) ) {
 299                         return null;
 300                 }
 301
 302                 return $format_ids[ $mime ];
 303         }
 304
 305         /**
 306          * Returns the localized name for a given content model,
 307          * or null of no mime type is known.
 308          *
 309          * Model names are localized using system messages. Message keys
 310          * have the form conent-model-$id.
 311          *
 312          * @static
 313          * @param int $id the content model id, as given by a CONTENT_MODEL_XXX constant
 314          *        or returned by Revision::getContentModel().
 315          *
 316          * @return String|null the content format's mime type.
 317          */
 318         public static function getContentModelName( $id ) {
 319                 $key = "content-model-$id";
 320
 321                 if ( wfEmptyMsg( $key ) ) return null;
 322                 else return wfMsg( $key );
 323         }
 324
 325         // ----------------------------------------------------------------------------------------------------------
 326
 327         protected $mModelID;
 328         protected $mSupportedFormats;
 329
 330         /**
 331          * Constructor, initializing the ContentHandler instance with it's model id and a list of supported formats.
 332          * Values for the parameters are typically provided as literals by subclasses' constructors.
 333          *
 334          * @param int $modelId (use CONTENT_MODEL_XXX constants).
 335          * @param array $formats list for supported serialization formats (typically as MIME types)
 336          */
 337         public function __construct( $modelId, $formats ) {
 338                 $this->mModelID = $modelId;
 339                 $this->mSupportedFormats = $formats;
 340         }
 341
 342
 343         /**
 344          * Serializes Content object of the type supported by this ContentHandler.
 345          *
 346          * @since WD.1
 347          *
 348          * @abstract
 349          * @param Content $content the Content object to serialize
 350          * @param null $format the desired serialization format
 351          * @return String serialized form of the content
 352          */
 353         public abstract function serializeContent( Content $content, $format = null );
 354
 355         /**
 356          * Unserializes a Content object of the type supported by this ContentHandler.
 357          *
 358          * @since WD.1
 359          *
 360          * @abstract
 361          * @param $blob String serialized form of the content
 362          * @param null $format the format used for serialization
 363          * @return Content the Content object created by deserializing $blob
 364          */
 365         public abstract function unserializeContent( $blob, $format = null );
 366
 367         /**
 368          * Creates an empty Content object of the type supported by this ContentHandler.
 369          *
 370          * @since WD.1
 371          *
 372          * @return Content
 373          */
 374         public abstract function makeEmptyContent();
 375
 376         /**
 377          * Returns the model id that identifies the content model this ContentHandler can handle.
 378          * Use with the CONTENT_MODEL_XXX constants.
 379          *
 380          * @since WD.1
 381          *
 382          * @return int the model id
 383          */
 384         public function getModelID() {
 385                 return $this->mModelID;
 386         }
 387
 388         /**
 389          * Throws an MWException if $model_id is not the id of the content model
 390          * supported by this ContentHandler.
 391          *
 392          * @since WD.1
 393          *
 394          * @param int $model_id the model to check
 395          */
 396         protected function checkModelID( $model_id ) {
 397                 if ( $model_id !== $this->mModelID ) {
 398                         $model_name = ContentHandler::getContentModelName( $model_id );
 399                         $own_model_name = ContentHandler::getContentModelName( $this->mModelID );
 400
 401                         throw new MWException( "Bad content model: expected {$this->mModelID} ($own_model_name) but got found $model_id ($model_name)." );
 402                 }
 403         }
 404
 405         /**
 406          * Returns a list of serialization formats supported by the serializeContent() and unserializeContent() methods of
 407          * this ContentHandler.
 408          *
 409          * @since WD.1
 410          *
 411          * @return array of serialization formats as MIME type like strings
 412          */
 413         public function getSupportedFormats() {
 414                 return $this->mSupportedFormats;
 415         }
 416
 417         /**
 418          * The format used for serialization/deserialization per default by this ContentHandler.
 419          *
 420          * This default implementation will return the first element of the array of formats
 421          * that was passed to the constructor.
 422          *
 423          * @since WD.1
 424          *
 425          * @return String the name of the default serialiozation format as a MIME type
 426          */
 427         public function getDefaultFormat() {
 428                 return $this->mSupportedFormats[0];
 429         }
 430
 431         /**
 432          * Returns true if $format is a serialization format supported by this ContentHandler,
 433          * and false otherwise.
 434          *
 435          * Note that if $format is null, this method always returns true, because null
 436          * means "use the default format".
 437          *
 438          * @since WD.1
 439          *
 440          * @param String $format the serialization format to check
 441          * @return bool
 442          */
 443         public function isSupportedFormat( $format ) {
 444
 445                 if ( !$format ) {
 446                         return true; // this means "use the default"
 447                 }
 448
 449                 return in_array( $format, $this->mSupportedFormats );
 450         }
 451
 452         /**
 453          * Throws an MWException if isSupportedFormat( $format ) is not true. Convenient
 454          * for checking whether a format provided as a parameter is actually supported.
 455          *
 456          * @param String $format the serialization format to check
 457          */
 458         protected function checkFormat( $format ) {
 459                 if ( !$this->isSupportedFormat( $format ) ) {
 460                         throw new MWException( "Format $format is not supported for content model " . $this->getModelID() );
 461                 }
 462         }
 463
 464         /**
 465          * Returns overrides for action handlers.
 466          * Classes listed here will be used instead of the default one when
 467          * (and only when) $wgActions[$action] === true. This allows subclasses
 468          * to override the default action handlers.
 469          *
 470          * @since WD.1
 471          *
 472          * @return Array
 473          */
 474         public function getActionOverrides() {
 475                 return array();
 476         }
 477
 478         /**
 479          * Return an Article object suitable for viewing the given object
 480          *
 481          * NOTE: does *not* do special handling for Image and Category pages!
 482          *       Use Article::newFromTitle() for that!
 483          *
 484          * @since WD.1
 485          *
 486          * @param Title $title
 487          * @return Article
 488          * @todo Article is being refactored into an action class, keep track of that
 489          * @todo Article really defines the view of the content... rename this method to createViewPage ?
 490          */
 491         public function createArticle( Title $title ) {
 492                 $this->checkModelID( $title->getContentModel() );
 493
 494                 $article = new Article($title);
 495                 return $article;
 496         }
 497
 498         /**
 499          * Return an EditPage object suitable for editing the given object.
 500          * This default  implementation always fails with an MWException, because there is no
 501          * generic edit page implementation suitable for all content models.
 502          *
 503          * @since WD.1
 504          *
 505          * @param Article $article
 506          * @return EditPage
 507          */
 508         public function createEditPage( Article $article ) {
 509                 throw new MWException( "ContentHandler class " . get_classs( $this ) . " does not provide an EditPage." );
 510         }
 511
 512         /**
 513          * Return an ExternalEdit object suitable for editing the given object
 514          *
 515          * @since WD.1
 516          *
 517          * @param IContextSource $context
 518          * @return ExternalEdit
 519          * @todo does anyone or anythign actually use the external edit facility? Can we just deprecate and ignore it?
 520          */
 521         public function createExternalEdit( IContextSource $context ) {
 522                 $this->checkModelID( $context->getTitle()->getContentModel() );
 523
 524                 $externalEdit = new ExternalEdit( $context );
 525                 return $externalEdit;
 526         }
 527
 528         /**
 529          * Factory
 530          * @since WD.1
 531          *
 532          * @param $context IContextSource context to use, anything else will be ignored
 533          * @param $old Integer old ID we want to show and diff with.
 534          * @param $new String either 'prev' or 'next'.
 535          * @param $rcid Integer ??? FIXME (default 0)
 536          * @param $refreshCache boolean If set, refreshes the diff cache
 537          * @param $unhide boolean If set, allow viewing deleted revs
 538          *
 539          * @return DifferenceEngine
 540          */
 541         public function createDifferenceEngine( IContextSource $context, $old = 0, $new = 0, $rcid = 0, #FIMXE: use everywhere!
 542                                                                                  $refreshCache = false, $unhide = false ) {
 543
 544                 $this->checkModelID( $context->getTitle()->getContentModel() );
 545
 546                 $diffEngineClass = $this->getDiffEngineClass();
 547
 548                 return new $diffEngineClass( $context, $old, $new, $rcid, $refreshCache, $unhide );
 549         }
 550
 551         /**
 552          * Returns the name of the diff engine to use.
 553          *
 554          * @since WD.1
 555          *
 556          * @return string
 557          */
 558         protected function getDiffEngineClass() {
 559                 return 'DifferenceEngine';
 560         }
 561
 562         /**
 563          * attempts to merge differences between three versions.
 564          * Returns a new Content object for a clean merge and false for failure or a conflict.
 565          *
 566          * This default implementation always returns false.
 567          *
 568          * @since WD.1
 569          *
 570          * @param $oldContent String
 571          * @param $myContent String
 572          * @param $yourContent String
 573          * @return Content|Bool
 574          */
 575         public function merge3( Content $oldContent, Content $myContent, Content $yourContent ) {
 576                 return false;
 577         }
 578
 579         /**
 580          * Return an applicable autosummary if one exists for the given edit.
 581          *
 582          * @since WD.1
 583          *
 584          * @param $oldContent Content|null: the previous text of the page.
 585          * @param $newContent Content|null: The submitted text of the page.
 586          * @param $flags Int bitmask: a bitmask of flags submitted for the edit.
 587          *
 588          * @return string An appropriate autosummary, or an empty string.
 589          */
 590         public function getAutosummary( Content $oldContent = null, Content $newContent = null, $flags ) {
 591                 global $wgContLang;
 592
 593                 // Decide what kind of autosummary is needed.
 594
 595                 // Redirect autosummaries
 596
 597                 /**
 598                  * @var $ot Title
 599                  * @var $rt Title
 600                  */
 601
 602                 $ot = !is_null( $oldContent ) ? $oldContent->getRedirectTarget() : null;
 603                 $rt = !is_null( $newContent ) ? $newContent->getRedirectTarget() : null;
 604
 605                 if ( is_object( $rt ) && ( !is_object( $ot ) || !$rt->equals( $ot ) || $ot->getFragment() != $rt->getFragment() ) ) {
 606
 607                         $truncatedtext = $newContent->getTextForSummary(
 608                                 250
 609                                         - strlen( wfMsgForContent( 'autoredircomment' ) )
 610                                         - strlen( $rt->getFullText() ) );
 611
 612                         return wfMsgForContent( 'autoredircomment', $rt->getFullText(), $truncatedtext );
 613                 }
 614
 615                 // New page autosummaries
 616                 if ( $flags & EDIT_NEW && $newContent->getSize() > 0 ) {
 617                         // If they're making a new article, give its text, truncated, in the summary.
 618
 619                         $truncatedtext = $newContent->getTextForSummary(
 620                                 200 - strlen( wfMsgForContent( 'autosumm-new' ) ) );
 621
 622                         return wfMsgForContent( 'autosumm-new', $truncatedtext );
 623                 }
 624
 625                 // Blanking autosummaries
 626                 if ( !empty( $oldContent ) && $oldContent->getSize() > 0 && $newContent->getSize() == 0 ) {
 627                         return wfMsgForContent( 'autosumm-blank' );
 628                 } elseif ( !empty( $oldContent ) && $oldContent->getSize() > 10 * $newContent->getSize() && $newContent->getSize() < 500 ) {
 629                         // Removing more than 90% of the article
 630
 631                         $truncatedtext = $newContent->getTextForSummary(
 632                                 200 - strlen( wfMsgForContent( 'autosumm-replace' ) ) );
 633
 634                         return wfMsgForContent( 'autosumm-replace', $truncatedtext );
 635                 }
 636
 637                 // If we reach this point, there's no applicable autosummary for our case, so our
 638                 // autosummary is empty.
 639
 640                 return '';
 641         }
 642
 643         /**
 644          * Auto-generates a deletion reason
 645          *
 646          * @since WD.1
 647          *
 648          * @param $title Title: the page's title
 649          * @param &$hasHistory Boolean: whether the page has a history
 650          * @return mixed String containing deletion reason or empty string, or boolean false
 651          *    if no revision occurred
 652          *
 653          * @XXX &$hasHistory is extremely ugly, it's here because WikiPage::getAutoDeleteReason() and Article::getReason() have it / want it.
 654          */
 655         public function getAutoDeleteReason( Title $title, &$hasHistory ) {
 656                 $dbw = wfGetDB( DB_MASTER );
 657
 658                 // Get the last revision
 659                 $rev = Revision::newFromTitle( $title );
 660
 661                 if ( is_null( $rev ) ) {
 662                         return false;
 663                 }
 664
 665                 // Get the article's contents
 666                 $content = $rev->getContent();
 667                 $blank = false;
 668
 669                 // If the page is blank, use the text from the previous revision,
 670                 // which can only be blank if there's a move/import/protect dummy revision involved
 671                 if ( $content->getSize() == 0 ) {
 672                         $prev = $rev->getPrevious();
 673
 674                         if ( $prev )    {
 675                                 $content = $rev->getContent();
 676                                 $blank = true;
 677                         }
 678                 }
 679
 680                 // Find out if there was only one contributor
 681                 // Only scan the last 20 revisions
 682                 $res = $dbw->select( 'revision', 'rev_user_text',
 683                         array( 'rev_page' => $title->getArticleID(), $dbw->bitAnd( 'rev_deleted', Revision::DELETED_USER ) . ' = 0' ),
 684                         __METHOD__,
 685                         array( 'LIMIT' => 20 )
 686                 );
 687
 688                 if ( $res === false ) {
 689                         // This page has no revisions, which is very weird
 690                         return false;
 691                 }
 692
 693                 $hasHistory = ( $res->numRows() > 1 );
 694                 $row = $dbw->fetchObject( $res );
 695
 696                 if ( $row ) { // $row is false if the only contributor is hidden
 697                         $onlyAuthor = $row->rev_user_text;
 698                         // Try to find a second contributor
 699                         foreach ( $res as $row ) {
 700                                 if ( $row->rev_user_text != $onlyAuthor ) { // Bug 22999
 701                                         $onlyAuthor = false;
 702                                         break;
 703                                 }
 704                         }
 705                 } else {
 706                         $onlyAuthor = false;
 707                 }
 708
 709                 // Generate the summary with a '$1' placeholder
 710                 if ( $blank ) {
 711                         // The current revision is blank and the one before is also
 712                         // blank. It's just not our lucky day
 713                         $reason = wfMsgForContent( 'exbeforeblank', '$1' );
 714                 } else {
 715                         if ( $onlyAuthor ) {
 716                                 $reason = wfMsgForContent( 'excontentauthor', '$1', $onlyAuthor );
 717                         } else {
 718                                 $reason = wfMsgForContent( 'excontent', '$1' );
 719                         }
 720                 }
 721
 722                 if ( $reason == '-' ) {
 723                         // Allow these UI messages to be blanked out cleanly
 724                         return '';
 725                 }
 726
 727                 // Max content length = max comment length - length of the comment (excl. $1)
 728                 $text = $content->getTextForSummary( 255 - ( strlen( $reason ) - 2 ) );
 729
 730                 // Now replace the '$1' placeholder
 731                 $reason = str_replace( '$1', $text, $reason );
 732
 733                 return $reason;
 734         }
 735
 736         #@TODO: getSecondaryUpdatesForDeletion( Content ) returns an array of DataUpdate objects
 737         #... or do that in the Content class?
 738
 739         /**
 740          * Get the Content object that needs to be saved in order to undo all revisions
 741          * between $undo and $undoafter. Revisions must belong to the same page,
 742          * must exist and must not be deleted
 743          *
 744          * @since WD.1
 745          *
 746          * @param $current Revision the current text
 747          * @param $undo Revision the revision to undo
 748          * @param $undoafter Revision Must be an earlier revision than $undo
 749          *
 750          * @return mixed string on success, false on failure
 751          */
 752         public function getUndoContent( Revision $current, Revision $undo, Revision $undoafter ) {
 753                 $cur_content = $current->getContent();
 754
 755                 if ( empty( $cur_content ) ) {
 756                         return false; // no page
 757                 }
 758
 759                 $undo_content = $undo->getContent();
 760                 $undoafter_content = $undoafter->getContent();
 761
 762                 if ( $cur_content->equals( $undo_content ) ) {
 763                         // No use doing a merge if it's just a straight revert.
 764                         return $undoafter_content;
 765                 }
 766
 767                 $undone_content = $this->merge3( $undo_content, $undoafter_content, $cur_content );
 768
 769                 return $undone_content;
 770         }
 771
 772         /**
 773          * Returns true for content models that support caching using the ParserCache mechanism.
 774          * See WikiPage::isParserCacheUser().
 775          *
 776          * @since WD.1
 777          *
 778          * @return bool
 779          */
 780         public function isParserCacheSupported() {
 781                 return true;
 782         }
 783
 784         /**
 785          * @since WD.1
 786          *
 787          * @param $page WikiPage the page that was deleted (note: $page->getId() must still return the old page ID!)
 788          *
 789          * @return array a list of DataUpdate instances that will clean up the database ofter deletion.
 790          */
 791         public function getDeletionUpdates( WikiPage $page ) {
 792                 return array(
 793                         new LinksDeletionUpdate( $page ),
 794                 );
 795         }
 796 }
 797
 798 /**
 799  * @since WD.1
 800  */
 801 abstract class TextContentHandler extends ContentHandler {
 802
 803         public function __construct( $modelId, $formats ) {
 804                 parent::__construct( $modelId, $formats );
 805         }
 806
 807         /**
 808          * Returns the content's text as-is.
 809          *
 810          * @param Content $content
 811          * @param String|null $format
 812          * @return mixed
 813          */
 814         public function serializeContent( Content $content, $format = null ) {
 815                 $this->checkFormat( $format );
 816                 return $content->getNativeData();
 817         }
 818
 819         /**
 820          * Return an EditPage object for editing the given object
 821          *
 822          * @since WD.1
 823          *
 824          * @param Article $article
 825          * @return EditPage
 826          */
 827         public function createEditPage( Article $article ) {
 828                 $this->checkModelID( $article->getPage()->getContentModel() );
 829
 830                 $editPage = new EditPage( $article );
 831                 return $editPage;
 832         }
 833
 834         /**
 835          * attempts to merge differences between three versions.
 836          * Returns a new Content object for a clean merge and false for failure or a conflict.
 837          *
 838          * All three Content objects passed as parameters must have the same content model.
 839          *
 840          * This text-based implementation uses wfMerge().
 841          *
 842          * @param $oldContent String
 843          * @param $myContent String
 844          * @param $yourContent String
 845          * @return Content|Bool
 846          */
 847         public function merge3( Content $oldContent, Content $myContent, Content $yourContent ) {
 848                 $this->checkModelID( $oldContent->getModel() );
 849                 $this->checkModelID( $myContent->getModel() );
 850                 $this->checkModelID( $yourContent->getModel() );
 851
 852                 $format = $this->getDefaultFormat();
 853
 854                 $old = $this->serializeContent( $oldContent, $format );
 855                 $mine = $this->serializeContent( $myContent, $format );
 856                 $yours = $this->serializeContent( $yourContent, $format );
 857
 858                 $ok = wfMerge( $old, $mine, $yours, $result );
 859
 860                 if ( !$ok ) {
 861                         return false;
 862                 }
 863
 864                 if ( !$result ) {
 865                         return $this->makeEmptyContent();
 866                 }
 867
 868                 $mergedContent = $this->unserializeContent( $result, $format );
 869                 return $mergedContent;
 870         }
 871
 872
 873 }
 874
 875 /**
 876  * @since WD.1
 877  */
 878 class WikitextContentHandler extends TextContentHandler {
 879
 880         public function __construct( $modelId = CONTENT_MODEL_WIKITEXT ) {
 881                 parent::__construct( $modelId, array( CONTENT_FORMAT_WIKITEXT ) );
 882         }
 883
 884         public function unserializeContent( $text, $format = null ) {
 885                 $this->checkFormat( $format );
 886
 887                 return new WikitextContent( $text );
 888         }
 889
 890         public function makeEmptyContent() {
 891                 return new WikitextContent( '' );
 892         }
 893
 894
 895 }
 896
 897 #XXX: make ScriptContentHandler base class with plugin interface for syntax highlighting?
 898
 899 /**
 900  * @since WD.1
 901  */
 902 class JavaScriptContentHandler extends TextContentHandler {
 903
 904         public function __construct( $modelId = CONTENT_MODEL_JAVASCRIPT ) {
 905                 parent::__construct( $modelId, array( CONTENT_FORMAT_JAVASCRIPT ) );
 906         }
 907
 908         public function unserializeContent( $text, $format = null ) {
 909                 $this->checkFormat( $format );
 910
 911                 return new JavaScriptContent( $text );
 912         }
 913
 914         public function makeEmptyContent() {
 915                 return new JavaScriptContent( '' );
 916         }
 917 }
 918
 919 /**
 920  * @since WD.1
 921  */
 922 class CssContentHandler extends TextContentHandler {
 923
 924         public function __construct( $modelId = CONTENT_MODEL_CSS ) {
 925                 parent::__construct( $modelId, array( CONTENT_FORMAT_CSS ) );
 926         }
 927
 928         public function unserializeContent( $text, $format = null ) {
 929                 $this->checkFormat( $format );
 930
 931                 return new CssContent( $text );
 932         }
 933
 934         public function makeEmptyContent() {
 935                 return new CssContent( '' );
 936         }
 937
 938 }