includes/content/Content.php

   1 <?php
   2 /**
   3  * A content object represents page content, e.g. the text to show on a page.
   4  * Content objects have no knowledge about how they relate to wiki pages.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License along
  17  * with this program; if not, write to the Free Software Foundation, Inc.,
  18  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  19  * http://www.gnu.org/copyleft/gpl.html
  20  *
  21  * @since 1.21
  22  *
  23  * @file
  24  * @ingroup Content
  25  *
  26  * @author Daniel Kinzler
  27  */
  28
  29 /**
  30  * Base interface for content objects.
  31  *
  32  * @ingroup Content
  33  */
  34 interface Content {
  35         /**
  36          * @since 1.21
  37          *
  38          * @return string A string representing the content in a way useful for
  39          *   building a full text search index. If no useful representation exists,
  40          *   this method returns an empty string.
  41          *
  42          * @todo Test that this actually works
  43          * @todo Make sure this also works with LuceneSearch / WikiSearch
  44          */
  45         public function getTextForSearchIndex();
  46
  47         /**
  48          * @since 1.21
  49          *
  50          * @return string|false The wikitext to include when another page includes this
  51          * content, or false if the content is not includable in a wikitext page.
  52          *
  53          * @todo Allow native handling, bypassing wikitext representation, like
  54          *  for includable special pages.
  55          * @todo Allow transclusion into other content models than Wikitext!
  56          * @todo Used in WikiPage and MessageCache to get message text. Not so
  57          *  nice. What should we use instead?!
  58          */
  59         public function getWikitextForTransclusion();
  60
  61         /**
  62          * Returns a textual representation of the content suitable for use in edit
  63          * summaries and log messages.
  64          *
  65          * @since 1.21
  66          *
  67          * @param int $maxLength Maximum length of the summary text
  68          * @return string The summary text
  69          */
  70         public function getTextForSummary( $maxLength = 250 );
  71
  72         /**
  73          * Returns native representation of the data. Interpretation depends on
  74          * the data model used, as given by getDataModel().
  75          *
  76          * @since 1.21
  77          *
  78          * @return mixed The native representation of the content. Could be a
  79          *    string, a nested array structure, an object, a binary blob...
  80          *    anything, really.
  81          *
  82          * @note Caller must be aware of content model!
  83          */
  84         public function getNativeData();
  85
  86         /**
  87          * Returns the content's nominal size in bogo-bytes.
  88          *
  89          * @return int
  90          */
  91         public function getSize();
  92
  93         /**
  94          * Returns the ID of the content model used by this Content object.
  95          * Corresponds to the CONTENT_MODEL_XXX constants.
  96          *
  97          * @since 1.21
  98          *
  99          * @return String The model id
 100          */
 101         public function getModel();
 102
 103         /**
 104          * Convenience method that returns the ContentHandler singleton for handling
 105          * the content model that this Content object uses.
 106          *
 107          * Shorthand for ContentHandler::getForContent( $this )
 108          *
 109          * @since 1.21
 110          *
 111          * @return ContentHandler
 112          */
 113         public function getContentHandler();
 114
 115         /**
 116          * Convenience method that returns the default serialization format for the
 117          * content model that this Content object uses.
 118          *
 119          * Shorthand for $this->getContentHandler()->getDefaultFormat()
 120          *
 121          * @since 1.21
 122          *
 123          * @return String
 124          */
 125         public function getDefaultFormat();
 126
 127         /**
 128          * Convenience method that returns the list of serialization formats
 129          * supported for the content model that this Content object uses.
 130          *
 131          * Shorthand for $this->getContentHandler()->getSupportedFormats()
 132          *
 133          * @since 1.21
 134          *
 135          * @return Array of supported serialization formats
 136          */
 137         public function getSupportedFormats();
 138
 139         /**
 140          * Returns true if $format is a supported serialization format for this
 141          * Content object, false if it isn't.
 142          *
 143          * Note that this should always return true if $format is null, because null
 144          * stands for the default serialization.
 145          *
 146          * Shorthand for $this->getContentHandler()->isSupportedFormat( $format )
 147          *
 148          * @since 1.21
 149          *
 150          * @param string $format The format to check
 151          * @return bool Whether the format is supported
 152          */
 153         public function isSupportedFormat( $format );
 154
 155         /**
 156          * Convenience method for serializing this Content object.
 157          *
 158          * Shorthand for $this->getContentHandler()->serializeContent( $this, $format )
 159          *
 160          * @since 1.21
 161          *
 162          * @param $format null|string The desired serialization format (or null for
 163          *    the default format).
 164          * @return string Serialized form of this Content object
 165          */
 166         public function serialize( $format = null );
 167
 168         /**
 169          * Returns true if this Content object represents empty content.
 170          *
 171          * @since 1.21
 172          *
 173          * @return bool Whether this Content object is empty
 174          */
 175         public function isEmpty();
 176
 177         /**
 178          * Returns whether the content is valid. This is intended for local validity
 179          * checks, not considering global consistency.
 180          *
 181          * Content needs to be valid before it can be saved.
 182          *
 183          * This default implementation always returns true.
 184          *
 185          * @since 1.21
 186          *
 187          * @return boolean
 188          */
 189         public function isValid();
 190
 191         /**
 192          * Returns true if this Content objects is conceptually equivalent to the
 193          * given Content object.
 194          *
 195          * Contract:
 196          *
 197          * - Will return false if $that is null.
 198          * - Will return true if $that === $this.
 199          * - Will return false if $that->getModel() != $this->getModel().
 200          * - Will return false if $that->getNativeData() is not equal to $this->getNativeData(),
 201          *   where the meaning of "equal" depends on the actual data model.
 202          *
 203          * Implementations should be careful to make equals() transitive and reflexive:
 204          *
 205          * - $a->equals( $b ) <=> $b->equals( $a )
 206          * - $a->equals( $b ) &&  $b->equals( $c ) ==> $a->equals( $c )
 207          *
 208          * @since 1.21
 209          *
 210          * @param $that Content The Content object to compare to
 211          * @return bool True if this Content object is equal to $that, false otherwise.
 212          */
 213         public function equals( Content $that = null );
 214
 215         /**
 216          * Return a copy of this Content object. The following must be true for the
 217          * object returned:
 218          *
 219          * if $copy = $original->copy()
 220          *
 221          * - get_class($original) === get_class($copy)
 222          * - $original->getModel() === $copy->getModel()
 223          * - $original->equals( $copy )
 224          *
 225          * If and only if the Content object is immutable, the copy() method can and
 226          * should return $this. That is, $copy === $original may be true, but only
 227          * for immutable content objects.
 228          *
 229          * @since 1.21
 230          *
 231          * @return Content. A copy of this object
 232          */
 233         public function copy();
 234
 235         /**
 236          * Returns true if this content is countable as a "real" wiki page, provided
 237          * that it's also in a countable location (e.g. a current revision in the
 238          * main namespace).
 239          *
 240          * @since 1.21
 241          *
 242          * @param bool $hasLinks If it is known whether this content contains
 243          *    links, provide this information here, to avoid redundant parsing to
 244          *    find out.
 245          * @return boolean
 246          */
 247         public function isCountable( $hasLinks = null );
 248
 249         /**
 250          * Parse the Content object and generate a ParserOutput from the result.
 251          * $result->getText() can be used to obtain the generated HTML. If no HTML
 252          * is needed, $generateHtml can be set to false; in that case,
 253          * $result->getText() may return null.
 254          *
 255          * @note To control which options are used in the cache key for the
 256          *       generated parser output, implementations of this method
 257          *       may call ParserOutput::recordOption() on the output object.
 258          *
 259          * @param $title Title The page title to use as a context for rendering
 260          * @param $revId null|int The revision being rendered (optional)
 261          * @param $options null|ParserOptions Any parser options
 262          * @param $generateHtml Boolean Whether to generate HTML (default: true). If false,
 263          *        the result of calling getText() on the ParserOutput object returned by
 264          *        this method is undefined.
 265          *
 266          * @since 1.21
 267          *
 268          * @return ParserOutput
 269          */
 270         public function getParserOutput( Title $title,
 271                 $revId = null,
 272                 ParserOptions $options = null, $generateHtml = true );
 273
 274         // TODO: make RenderOutput and RenderOptions base classes
 275
 276         /**
 277          * Returns a list of DataUpdate objects for recording information about this
 278          * Content in some secondary data store. If the optional second argument,
 279          * $old, is given, the updates may model only the changes that need to be
 280          * made to replace information about the old content with information about
 281          * the new content.
 282          *
 283          * This default implementation calls
 284          * $this->getParserOutput( $content, $title, null, null, false ),
 285          * and then calls getSecondaryDataUpdates( $title, $recursive ) on the
 286          * resulting ParserOutput object.
 287          *
 288          * Subclasses may implement this to determine the necessary updates more
 289          * efficiently, or make use of information about the old content.
 290          *
 291          * @param $title Title The context for determining the necessary updates
 292          * @param $old Content|null An optional Content object representing the
 293          *    previous content, i.e. the content being replaced by this Content
 294          *    object.
 295          * @param $recursive boolean Whether to include recursive updates (default:
 296          *    false).
 297          * @param $parserOutput ParserOutput|null Optional ParserOutput object.
 298          *    Provide if you have one handy, to avoid re-parsing of the content.
 299          *
 300          * @return Array. A list of DataUpdate objects for putting information
 301          *    about this content object somewhere.
 302          *
 303          * @since 1.21
 304          */
 305         public function getSecondaryDataUpdates( Title $title,
 306                 Content $old = null,
 307                 $recursive = true, ParserOutput $parserOutput = null
 308         );
 309
 310         /**
 311          * Construct the redirect destination from this content and return an
 312          * array of Titles, or null if this content doesn't represent a redirect.
 313          * The last element in the array is the final destination after all redirects
 314          * have been resolved (up to $wgMaxRedirects times).
 315          *
 316          * @since 1.21
 317          *
 318          * @return Array of Titles, with the destination last
 319          */
 320         public function getRedirectChain();
 321
 322         /**
 323          * Construct the redirect destination from this content and return a Title,
 324          * or null if this content doesn't represent a redirect.
 325          * This will only return the immediate redirect target, useful for
 326          * the redirect table and other checks that don't need full recursion.
 327          *
 328          * @since 1.21
 329          *
 330          * @return Title: The corresponding Title
 331          */
 332         public function getRedirectTarget();
 333
 334         /**
 335          * Construct the redirect destination from this content and return the
 336          * Title, or null if this content doesn't represent a redirect.
 337          *
 338          * This will recurse down $wgMaxRedirects times or until a non-redirect
 339          * target is hit in order to provide (hopefully) the Title of the final
 340          * destination instead of another redirect.
 341          *
 342          * There is usually no need to override the default behavior, subclasses that
 343          * want to implement redirects should override getRedirectTarget().
 344          *
 345          * @since 1.21
 346          *
 347          * @return Title
 348          */
 349         public function getUltimateRedirectTarget();
 350
 351         /**
 352          * Returns whether this Content represents a redirect.
 353          * Shorthand for getRedirectTarget() !== null.
 354          *
 355          * @since 1.21
 356          *
 357          * @return bool
 358          */
 359         public function isRedirect();
 360
 361         /**
 362          * If this Content object is a redirect, this method updates the redirect target.
 363          * Otherwise, it does nothing.
 364          *
 365          * @since 1.21
 366          *
 367          * @param Title $target the new redirect target
 368          *
 369          * @return Content a new Content object with the updated redirect (or $this
 370          *   if this Content object isn't a redirect)
 371          */
 372         public function updateRedirect( Title $target );
 373
 374         /**
 375          * Returns the section with the given ID.
 376          *
 377          * @since 1.21
 378          *
 379          * @param string $sectionId The section's ID, given as a numeric string.
 380          *    The ID "0" retrieves the section before the first heading, "1" the
 381          *    text between the first heading (included) and the second heading
 382          *    (excluded), etc.
 383          * @return Content|Boolean|null The section, or false if no such section
 384          *    exist, or null if sections are not supported.
 385          */
 386         public function getSection( $sectionId );
 387
 388         /**
 389          * Replaces a section of the content and returns a Content object with the
 390          * section replaced.
 391          *
 392          * @since 1.21
 393          *
 394          * @param $section null/false or a section number (0, 1, 2, T1, T2...), or "new"
 395          * @param $with Content: new content of the section
 396          * @param string $sectionTitle new section's subject, only if $section is 'new'
 397          * @return string Complete article text, or null if error
 398          */
 399         public function replaceSection( $section, Content $with, $sectionTitle = '' );
 400
 401         /**
 402          * Returns a Content object with pre-save transformations applied (or this
 403          * object if no transformations apply).
 404          *
 405          * @since 1.21
 406          *
 407          * @param $title Title
 408          * @param $user User
 409          * @param $parserOptions null|ParserOptions
 410          * @return Content
 411          */
 412         public function preSaveTransform( Title $title, User $user, ParserOptions $parserOptions );
 413
 414         /**
 415          * Returns a new WikitextContent object with the given section heading
 416          * prepended, if supported. The default implementation just returns this
 417          * Content object unmodified, ignoring the section header.
 418          *
 419          * @since 1.21
 420          *
 421          * @param $header string
 422          * @return Content
 423          */
 424         public function addSectionHeader( $header );
 425
 426         /**
 427          * Returns a Content object with preload transformations applied (or this
 428          * object if no transformations apply).
 429          *
 430          * @since 1.21
 431          *
 432          * @param $title Title
 433          * @param $parserOptions null|ParserOptions
 434          * @return Content
 435          */
 436         public function preloadTransform( Title $title, ParserOptions $parserOptions );
 437
 438         /**
 439          * Prepare Content for saving. Called before Content is saved by WikiPage::doEditContent() and in
 440          * similar places.
 441          *
 442          * This may be used to check the content's consistency with global state. This function should
 443          * NOT write any information to the database.
 444          *
 445          * Note that this method will usually be called inside the same transaction
 446          * bracket that will be used to save the new revision.
 447          *
 448          * Note that this method is called before any update to the page table is
 449          * performed. This means that $page may not yet know a page ID.
 450          *
 451          * @since 1.21
 452          *
 453          * @param WikiPage $page The page to be saved.
 454          * @param int $flags bitfield for use with EDIT_XXX constants, see WikiPage::doEditContent()
 455          * @param int $baseRevId the ID of the current revision
 456          * @param User $user
 457          *
 458          * @return Status A status object indicating whether the content was
 459          *   successfully prepared for saving. If the returned status indicates
 460          *   an error, a rollback will be performed and the transaction aborted.
 461          *
 462          * @see see WikiPage::doEditContent()
 463          */
 464         public function prepareSave( WikiPage $page, $flags, $baseRevId, User $user );
 465
 466         /**
 467          * Returns a list of updates to perform when this content is deleted.
 468          * The necessary updates may be taken from the Content object, or depend on
 469          * the current state of the database.
 470          *
 471          * @since 1.21
 472          *
 473          * @param $page WikiPage the deleted page
 474          * @param $parserOutput null|ParserOutput optional parser output object
 475          *    for efficient access to meta-information about the content object.
 476          *    Provide if you have one handy.
 477          *
 478          * @return array A list of DataUpdate instances that will clean up the
 479          *    database after deletion.
 480          */
 481         public function getDeletionUpdates( WikiPage $page,
 482                 ParserOutput $parserOutput = null );
 483
 484         /**
 485          * Returns true if this Content object matches the given magic word.
 486          *
 487          * @since 1.21
 488          *
 489          * @param MagicWord $word the magic word to match
 490          *
 491          * @return bool whether this Content object matches the given magic word.
 492          */
 493         public function matchMagicWord( MagicWord $word );
 494
 495         /**
 496          * Converts this content object into another content object with the given content model,
 497          * if that is possible.
 498          *
 499          * @param string $toModel the desired content model, use the CONTENT_MODEL_XXX flags.
 500          * @param string $lossy flag, set to "lossy" to allow lossy conversion. If lossy conversion is
 501          * not allowed, full round-trip conversion is expected to work without losing information.
 502          *
 503          * @return Content|bool A content object with the content model $toModel, or false if
 504          * that conversion is not supported.
 505          */
 506         public function convert( $toModel, $lossy = '' );
 507         // @todo ImagePage and CategoryPage interfere with per-content action handlers
 508         // @todo nice&sane integration of GeSHi syntax highlighting
 509         //   [11:59] <vvv> Hooks are ugly; make CodeHighlighter interface and a
 510         //   config to set the class which handles syntax highlighting
 511         //   [12:00] <vvv> And default it to a DummyHighlighter
 512 }