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         /**
  37          * @since 1.21
  38          *
  39          * @return string A string representing the content in a way useful for
  40          *   building a full text search index. If no useful representation exists,
  41          *   this method returns an empty string.
  42          *
  43          * @todo Test that this actually works
  44          * @todo Make sure this also works with LuceneSearch / WikiSearch
  45          */
  46         public function getTextForSearchIndex();
  47
  48         /**
  49          * @since 1.21
  50          *
  51          * @return string|bool The wikitext to include when another page includes this
  52          * content, or false if the content is not includable in a wikitext page.
  53          *
  54          * @todo Allow native handling, bypassing wikitext representation, like
  55          *  for includable special pages.
  56          * @todo Allow transclusion into other content models than Wikitext!
  57          * @todo Used in WikiPage and MessageCache to get message text. Not so
  58          *  nice. What should we use instead?!
  59          */
  60         public function getWikitextForTransclusion();
  61
  62         /**
  63          * Returns a textual representation of the content suitable for use in edit
  64          * summaries and log messages.
  65          *
  66          * @since 1.21
  67          *
  68          * @param int $maxLength Maximum length of the summary text.
  69          *
  70          * @return string The summary text.
  71          */
  72         public function getTextForSummary( $maxLength = 250 );
  73
  74         /**
  75          * Returns native representation of the data. Interpretation depends on
  76          * the data model used, as given by getDataModel().
  77          *
  78          * @since 1.21
  79          *
  80          * @return mixed The native representation of the content. Could be a
  81          *    string, a nested array structure, an object, a binary blob...
  82          *    anything, really.
  83          *
  84          * @note Caller must be aware of content model!
  85          */
  86         public function getNativeData();
  87
  88         /**
  89          * Returns the content's nominal size in "bogo-bytes".
  90          *
  91          * @return int
  92          */
  93         public function getSize();
  94
  95         /**
  96          * Returns the ID of the content model used by this Content object.
  97          * Corresponds to the CONTENT_MODEL_XXX constants.
  98          *
  99          * @since 1.21
 100          *
 101          * @return string The model id
 102          */
 103         public function getModel();
 104
 105         /**
 106          * Convenience method that returns the ContentHandler singleton for handling
 107          * the content model that this Content object uses.
 108          *
 109          * Shorthand for ContentHandler::getForContent( $this )
 110          *
 111          * @since 1.21
 112          *
 113          * @return ContentHandler
 114          */
 115         public function getContentHandler();
 116
 117         /**
 118          * Convenience method that returns the default serialization format for the
 119          * content model that this Content object uses.
 120          *
 121          * Shorthand for $this->getContentHandler()->getDefaultFormat()
 122          *
 123          * @since 1.21
 124          *
 125          * @return string
 126          */
 127         public function getDefaultFormat();
 128
 129         /**
 130          * Convenience method that returns the list of serialization formats
 131          * supported for the content model that this Content object uses.
 132          *
 133          * Shorthand for $this->getContentHandler()->getSupportedFormats()
 134          *
 135          * @since 1.21
 136          *
 137          * @return string[] List of supported serialization formats
 138          */
 139         public function getSupportedFormats();
 140
 141         /**
 142          * Returns true if $format is a supported serialization format for this
 143          * Content object, false if it isn't.
 144          *
 145          * Note that this should always return true if $format is null, because null
 146          * stands for the default serialization.
 147          *
 148          * Shorthand for $this->getContentHandler()->isSupportedFormat( $format )
 149          *
 150          * @since 1.21
 151          *
 152          * @param string $format The serialization format to check.
 153          *
 154          * @return bool Whether the format is supported
 155          */
 156         public function isSupportedFormat( $format );
 157
 158         /**
 159          * Convenience method for serializing this Content object.
 160          *
 161          * Shorthand for $this->getContentHandler()->serializeContent( $this, $format )
 162          *
 163          * @since 1.21
 164          *
 165          * @param string $format The desired serialization format, or null for the default format.
 166          *
 167          * @return string Serialized form of this Content object.
 168          */
 169         public function serialize( $format = null );
 170
 171         /**
 172          * Returns true if this Content object represents empty content.
 173          *
 174          * @since 1.21
 175          *
 176          * @return bool Whether this Content object is empty
 177          */
 178         public function isEmpty();
 179
 180         /**
 181          * Returns whether the content is valid. This is intended for local validity
 182          * checks, not considering global consistency.
 183          *
 184          * Content needs to be valid before it can be saved.
 185          *
 186          * This default implementation always returns true.
 187          *
 188          * @since 1.21
 189          *
 190          * @return bool
 191          */
 192         public function isValid();
 193
 194         /**
 195          * Returns true if this Content objects is conceptually equivalent to the
 196          * given Content object.
 197          *
 198          * Contract:
 199          *
 200          * - Will return false if $that is null.
 201          * - Will return true if $that === $this.
 202          * - Will return false if $that->getModel() != $this->getModel().
 203          * - Will return false if $that->getNativeData() is not equal to $this->getNativeData(),
 204          *   where the meaning of "equal" depends on the actual data model.
 205          *
 206          * Implementations should be careful to make equals() transitive and reflexive:
 207          *
 208          * - $a->equals( $b ) <=> $b->equals( $a )
 209          * - $a->equals( $b ) &&  $b->equals( $c ) ==> $a->equals( $c )
 210          *
 211          * @since 1.21
 212          *
 213          * @param Content $that The Content object to compare to.
 214          *
 215          * @return bool True if this Content object is equal to $that, false otherwise.
 216          */
 217         public function equals( Content $that = null );
 218
 219         /**
 220          * Return a copy of this Content object. The following must be true for the
 221          * object returned:
 222          *
 223          * if $copy = $original->copy()
 224          *
 225          * - get_class($original) === get_class($copy)
 226          * - $original->getModel() === $copy->getModel()
 227          * - $original->equals( $copy )
 228          *
 229          * If and only if the Content object is immutable, the copy() method can and
 230          * should return $this. That is, $copy === $original may be true, but only
 231          * for immutable content objects.
 232          *
 233          * @since 1.21
 234          *
 235          * @return Content A copy of this object
 236          */
 237         public function copy();
 238
 239         /**
 240          * Returns true if this content is countable as a "real" wiki page, provided
 241          * that it's also in a countable location (e.g. a current revision in the
 242          * main namespace).
 243          *
 244          * @since 1.21
 245          *
 246          * @param bool $hasLinks If it is known whether this content contains
 247          *    links, provide this information here, to avoid redundant parsing to
 248          *    find out.
 249          *
 250          * @return bool
 251          */
 252         public function isCountable( $hasLinks = null );
 253
 254         /**
 255          * Parse the Content object and generate a ParserOutput from the result.
 256          * $result->getText() can be used to obtain the generated HTML. If no HTML
 257          * is needed, $generateHtml can be set to false; in that case,
 258          * $result->getText() may return null.
 259          *
 260          * @note To control which options are used in the cache key for the
 261          *       generated parser output, implementations of this method
 262          *       may call ParserOutput::recordOption() on the output object.
 263          *
 264          * @param Title $title The page title to use as a context for rendering.
 265          * @param int $revId Optional revision ID being rendered.
 266          * @param ParserOptions $options Any parser options.
 267          * @param bool $generateHtml Whether to generate HTML (default: true). If false,
 268          *        the result of calling getText() on the ParserOutput object returned by
 269          *        this method is undefined.
 270          *
 271          * @since 1.21
 272          *
 273          * @return ParserOutput
 274          */
 275         public function getParserOutput( Title $title, $revId = null,
 276                 ParserOptions $options = null, $generateHtml = true );
 277
 278         // TODO: make RenderOutput and RenderOptions base classes
 279
 280         /**
 281          * Returns a list of DataUpdate objects for recording information about this
 282          * Content in some secondary data store. If the optional second argument,
 283          * $old, is given, the updates may model only the changes that need to be
 284          * made to replace information about the old content with information about
 285          * the new content.
 286          *
 287          * This default implementation calls
 288          * $this->getParserOutput( $content, $title, null, null, false ),
 289          * and then calls getSecondaryDataUpdates( $title, $recursive ) on the
 290          * resulting ParserOutput object.
 291          *
 292          * Subclasses may implement this to determine the necessary updates more
 293          * efficiently, or make use of information about the old content.
 294          *
 295          * @param Title $title The context for determining the necessary updates
 296          * @param Content $old An optional Content object representing the
 297          *    previous content, i.e. the content being replaced by this Content
 298          *    object.
 299          * @param bool $recursive Whether to include recursive updates (default:
 300          *    false).
 301          * @param ParserOutput $parserOutput Optional ParserOutput object.
 302          *    Provide if you have one handy, to avoid re-parsing of the content.
 303          *
 304          * @return DataUpdate[] A list of DataUpdate objects for putting information
 305          *    about this content object somewhere.
 306          *
 307          * @since 1.21
 308          */
 309         public function getSecondaryDataUpdates( Title $title, Content $old = null,
 310                 $recursive = true, ParserOutput $parserOutput = null );
 311
 312         /**
 313          * Construct the redirect destination from this content and return an
 314          * array of Titles, or null if this content doesn't represent a redirect.
 315          * The last element in the array is the final destination after all redirects
 316          * have been resolved (up to $wgMaxRedirects times).
 317          *
 318          * @since 1.21
 319          *
 320          * @return Title[]|null List of Titles, with the destination last.
 321          */
 322         public function getRedirectChain();
 323
 324         /**
 325          * Construct the redirect destination from this content and return a Title,
 326          * or null if this content doesn't represent a redirect.
 327          * This will only return the immediate redirect target, useful for
 328          * the redirect table and other checks that don't need full recursion.
 329          *
 330          * @since 1.21
 331          *
 332          * @return Title|null The corresponding Title.
 333          */
 334         public function getRedirectTarget();
 335
 336         /**
 337          * Construct the redirect destination from this content and return the
 338          * Title, or null if this content doesn't represent a redirect.
 339          *
 340          * This will recurse down $wgMaxRedirects times or until a non-redirect
 341          * target is hit in order to provide (hopefully) the Title of the final
 342          * destination instead of another redirect.
 343          *
 344          * There is usually no need to override the default behavior, subclasses that
 345          * want to implement redirects should override getRedirectTarget().
 346          *
 347          * @since 1.21
 348          *
 349          * @return Title|null
 350          */
 351         public function getUltimateRedirectTarget();
 352
 353         /**
 354          * Returns whether this Content represents a redirect.
 355          * Shorthand for getRedirectTarget() !== null.
 356          *
 357          * @since 1.21
 358          *
 359          * @return bool
 360          */
 361         public function isRedirect();
 362
 363         /**
 364          * If this Content object is a redirect, this method updates the redirect target.
 365          * Otherwise, it does nothing.
 366          *
 367          * @since 1.21
 368          *
 369          * @param Title $target The new redirect target
 370          *
 371          * @return Content A new Content object with the updated redirect (or $this
 372          *   if this Content object isn't a redirect)
 373          */
 374         public function updateRedirect( Title $target );
 375
 376         /**
 377          * Returns the section with the given ID.
 378          *
 379          * @since 1.21
 380          *
 381          * @param string|number $sectionId Section identifier as a number or string
 382          * (e.g. 0, 1 or 'T-1'). The ID "0" retrieves the section before the first heading, "1" the
 383          * text between the first heading (included) and the second heading (excluded), etc.
 384          *
 385          * @return Content|bool|null The section, or false if no such section
 386          *    exist, or null if sections are not supported.
 387          */
 388         public function getSection( $sectionId );
 389
 390         /**
 391          * Replaces a section of the content and returns a Content object with the
 392          * section replaced.
 393          *
 394          * @since 1.21
 395          *
 396          * @param string|number|null|bool $sectionId Section identifier as a number or string
 397          * (e.g. 0, 1 or 'T-1'), null/false or an empty string for the whole page
 398          * or 'new' for a new section.
 399          * @param Content $with New content of the section
 400          * @param string $sectionTitle New section's subject, only if $section is 'new'
 401          *
 402          * @return string|null Complete article text, or null if error
 403          */
 404         public function replaceSection( $sectionId, Content $with, $sectionTitle = '' );
 405
 406         /**
 407          * Returns a Content object with pre-save transformations applied (or this
 408          * object if no transformations apply).
 409          *
 410          * @since 1.21
 411          *
 412          * @param Title $title
 413          * @param User $user
 414          * @param ParserOptions $parserOptions
 415          *
 416          * @return Content
 417          */
 418         public function preSaveTransform( Title $title, User $user, ParserOptions $parserOptions );
 419
 420         /**
 421          * Returns a new WikitextContent object with the given section heading
 422          * prepended, if supported. The default implementation just returns this
 423          * Content object unmodified, ignoring the section header.
 424          *
 425          * @since 1.21
 426          *
 427          * @param string $header
 428          *
 429          * @return Content
 430          */
 431         public function addSectionHeader( $header );
 432
 433         /**
 434          * Returns a Content object with preload transformations applied (or this
 435          * object if no transformations apply).
 436          *
 437          * @since 1.21
 438          *
 439          * @param Title $title
 440          * @param ParserOptions $parserOptions
 441          * @param array $params
 442          *
 443          * @return Content
 444          */
 445         public function preloadTransform( Title $title, ParserOptions $parserOptions, $params = array() );
 446
 447         /**
 448          * Prepare Content for saving. Called before Content is saved by WikiPage::doEditContent() and in
 449          * similar places.
 450          *
 451          * This may be used to check the content's consistency with global state. This function should
 452          * NOT write any information to the database.
 453          *
 454          * Note that this method will usually be called inside the same transaction
 455          * bracket that will be used to save the new revision.
 456          *
 457          * Note that this method is called before any update to the page table is
 458          * performed. This means that $page may not yet know a page ID.
 459          *
 460          * @since 1.21
 461          *
 462          * @param WikiPage $page The page to be saved.
 463          * @param int $flags Bitfield for use with EDIT_XXX constants, see WikiPage::doEditContent()
 464          * @param int $baseRevId The ID of the current revision
 465          * @param User $user
 466          *
 467          * @return Status A status object indicating whether the content was
 468          *   successfully prepared for saving. If the returned status indicates
 469          *   an error, a rollback will be performed and the transaction aborted.
 470          *
 471          * @see WikiPage::doEditContent()
 472          */
 473         public function prepareSave( WikiPage $page, $flags, $baseRevId, User $user );
 474
 475         /**
 476          * Returns a list of updates to perform when this content is deleted.
 477          * The necessary updates may be taken from the Content object, or depend on
 478          * the current state of the database.
 479          *
 480          * @since 1.21
 481          *
 482          * @param WikiPage $page The deleted page
 483          * @param ParserOutput $parserOutput Optional parser output object
 484          *    for efficient access to meta-information about the content object.
 485          *    Provide if you have one handy.
 486          *
 487          * @return DataUpdate[] A list of DataUpdate instances that will clean up the
 488          *    database after deletion.
 489          */
 490         public function getDeletionUpdates( WikiPage $page,
 491                 ParserOutput $parserOutput = null );
 492
 493         /**
 494          * Returns true if this Content object matches the given magic word.
 495          *
 496          * @since 1.21
 497          *
 498          * @param MagicWord $word The magic word to match
 499          *
 500          * @return bool Whether this Content object matches the given magic word.
 501          */
 502         public function matchMagicWord( MagicWord $word );
 503
 504         /**
 505          * Converts this content object into another content object with the given content model,
 506          * if that is possible.
 507          *
 508          * @param string $toModel The desired content model, use the CONTENT_MODEL_XXX flags.
 509          * @param string $lossy Optional flag, set to "lossy" to allow lossy conversion. If lossy
 510          * conversion is not allowed, full round-trip conversion is expected to work without losing
 511          * information.
 512          *
 513          * @return Content|bool A content object with the content model $toModel, or false if
 514          * that conversion is not supported.
 515          */
 516         public function convert( $toModel, $lossy = '' );
 517         // @todo ImagePage and CategoryPage interfere with per-content action handlers
 518         // @todo nice&sane integration of GeSHi syntax highlighting
 519         //   [11:59] <vvv> Hooks are ugly; make CodeHighlighter interface and a
 520         //   config to set the class which handles syntax highlighting
 521         //   [12:00] <vvv> And default it to a DummyHighlighter
 522
 523 }