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