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   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  }