includes/api/ApiQuery.php

   1 <?php
   2 /**
   3  *
   4  *
   5  * Created on Sep 7, 2006
   6  *
   7  * Copyright © 2006 Yuri Astrakhan "<Firstname><Lastname>@gmail.com"
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License as published by
  11  * the Free Software Foundation; either version 2 of the License, or
  12  * (at your option) any later version.
  13  *
  14  * This program is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  17  * GNU General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU General Public License along
  20  * with this program; if not, write to the Free Software Foundation, Inc.,
  21  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  22  * http://www.gnu.org/copyleft/gpl.html
  23  *
  24  * @file
  25  */
  26
  27 /**
  28  * This is the main query class. It behaves similar to ApiMain: based on the
  29  * parameters given, it will create a list of titles to work on (an ApiPageSet
  30  * object), instantiate and execute various property/list/meta modules, and
  31  * assemble all resulting data into a single ApiResult object.
  32  *
  33  * In generator mode, a generator will be executed first to populate a second
  34  * ApiPageSet object, and that object will be used for all subsequent modules.
  35  *
  36  * @ingroup API
  37  */
  38 class ApiQuery extends ApiBase {
  39
  40         /**
  41          * List of Api Query prop modules
  42          * @var array
  43          */
  44         private static $QueryPropModules = array(
  45                 'categories' => 'ApiQueryCategories',
  46                 'categoryinfo' => 'ApiQueryCategoryInfo',
  47                 'contributors' => 'ApiQueryContributors',
  48                 'duplicatefiles' => 'ApiQueryDuplicateFiles',
  49                 'extlinks' => 'ApiQueryExternalLinks',
  50                 'fileusage' => 'ApiQueryBacklinksprop',
  51                 'images' => 'ApiQueryImages',
  52                 'imageinfo' => 'ApiQueryImageInfo',
  53                 'info' => 'ApiQueryInfo',
  54                 'links' => 'ApiQueryLinks',
  55                 'linkshere' => 'ApiQueryBacklinksprop',
  56                 'iwlinks' => 'ApiQueryIWLinks',
  57                 'langlinks' => 'ApiQueryLangLinks',
  58                 'pageprops' => 'ApiQueryPageProps',
  59                 'redirects' => 'ApiQueryBacklinksprop',
  60                 'revisions' => 'ApiQueryRevisions',
  61                 'stashimageinfo' => 'ApiQueryStashImageInfo',
  62                 'templates' => 'ApiQueryLinks',
  63                 'transcludedin' => 'ApiQueryBacklinksprop',
  64         );
  65
  66         /**
  67          * List of Api Query list modules
  68          * @var array
  69          */
  70         private static $QueryListModules = array(
  71                 'allcategories' => 'ApiQueryAllCategories',
  72                 'allfileusages' => 'ApiQueryAllLinks',
  73                 'allimages' => 'ApiQueryAllImages',
  74                 'alllinks' => 'ApiQueryAllLinks',
  75                 'allpages' => 'ApiQueryAllPages',
  76                 'allredirects' => 'ApiQueryAllLinks',
  77                 'alltransclusions' => 'ApiQueryAllLinks',
  78                 'allusers' => 'ApiQueryAllUsers',
  79                 'backlinks' => 'ApiQueryBacklinks',
  80                 'blocks' => 'ApiQueryBlocks',
  81                 'categorymembers' => 'ApiQueryCategoryMembers',
  82                 'deletedrevs' => 'ApiQueryDeletedrevs',
  83                 'embeddedin' => 'ApiQueryBacklinks',
  84                 'exturlusage' => 'ApiQueryExtLinksUsage',
  85                 'filearchive' => 'ApiQueryFilearchive',
  86                 'imageusage' => 'ApiQueryBacklinks',
  87                 'iwbacklinks' => 'ApiQueryIWBacklinks',
  88                 'langbacklinks' => 'ApiQueryLangBacklinks',
  89                 'logevents' => 'ApiQueryLogEvents',
  90                 'pageswithprop' => 'ApiQueryPagesWithProp',
  91                 'pagepropnames' => 'ApiQueryPagePropNames',
  92                 'prefixsearch' => 'ApiQueryPrefixSearch',
  93                 'protectedtitles' => 'ApiQueryProtectedTitles',
  94                 'querypage' => 'ApiQueryQueryPage',
  95                 'random' => 'ApiQueryRandom',
  96                 'recentchanges' => 'ApiQueryRecentChanges',
  97                 'search' => 'ApiQuerySearch',
  98                 'tags' => 'ApiQueryTags',
  99                 'usercontribs' => 'ApiQueryContributions',
 100                 'users' => 'ApiQueryUsers',
 101                 'watchlist' => 'ApiQueryWatchlist',
 102                 'watchlistraw' => 'ApiQueryWatchlistRaw',
 103         );
 104
 105         /**
 106          * List of Api Query meta modules
 107          * @var array
 108          */
 109         private static $QueryMetaModules = array(
 110                 'allmessages' => 'ApiQueryAllMessages',
 111                 'siteinfo' => 'ApiQuerySiteinfo',
 112                 'userinfo' => 'ApiQueryUserInfo',
 113                 'filerepoinfo' => 'ApiQueryFileRepoInfo',
 114                 'tokens' => 'ApiQueryTokens',
 115         );
 116
 117         /**
 118          * @var ApiPageSet
 119          */
 120         private $mPageSet;
 121
 122         private $mParams;
 123         private $mNamedDB = array();
 124         private $mModuleMgr;
 125
 126         /**
 127          * @param ApiMain $main
 128          * @param string $action
 129          */
 130         public function __construct( ApiMain $main, $action ) {
 131                 parent::__construct( $main, $action );
 132
 133                 $this->mModuleMgr = new ApiModuleManager( $this );
 134
 135                 // Allow custom modules to be added in LocalSettings.php
 136                 $config = $this->getConfig();
 137                 $this->mModuleMgr->addModules( self::$QueryPropModules, 'prop' );
 138                 $this->mModuleMgr->addModules( $config->get( 'APIPropModules' ), 'prop' );
 139                 $this->mModuleMgr->addModules( self::$QueryListModules, 'list' );
 140                 $this->mModuleMgr->addModules( $config->get( 'APIListModules' ), 'list' );
 141                 $this->mModuleMgr->addModules( self::$QueryMetaModules, 'meta' );
 142                 $this->mModuleMgr->addModules( $config->get( 'APIMetaModules' ), 'meta' );
 143
 144                 // Create PageSet that will process titles/pageids/revids/generator
 145                 $this->mPageSet = new ApiPageSet( $this );
 146         }
 147
 148         /**
 149          * Overrides to return this instance's module manager.
 150          * @return ApiModuleManager
 151          */
 152         public function getModuleManager() {
 153                 return $this->mModuleMgr;
 154         }
 155
 156         /**
 157          * Get the query database connection with the given name.
 158          * If no such connection has been requested before, it will be created.
 159          * Subsequent calls with the same $name will return the same connection
 160          * as the first, regardless of the values of $db and $groups
 161          * @param string $name Name to assign to the database connection
 162          * @param int $db One of the DB_* constants
 163          * @param array $groups Query groups
 164          * @return DatabaseBase
 165          */
 166         public function getNamedDB( $name, $db, $groups ) {
 167                 if ( !array_key_exists( $name, $this->mNamedDB ) ) {
 168                         $this->profileDBIn();
 169                         $this->mNamedDB[$name] = wfGetDB( $db, $groups );
 170                         $this->profileDBOut();
 171                 }
 172
 173                 return $this->mNamedDB[$name];
 174         }
 175
 176         /**
 177          * Gets the set of pages the user has requested (or generated)
 178          * @return ApiPageSet
 179          */
 180         public function getPageSet() {
 181                 return $this->mPageSet;
 182         }
 183
 184         /**
 185          * Get the array mapping module names to class names
 186          * @deprecated since 1.21, use getModuleManager()'s methods instead
 187          * @return array Array(modulename => classname)
 188          */
 189         public function getModules() {
 190                 wfDeprecated( __METHOD__, '1.21' );
 191
 192                 return $this->getModuleManager()->getNamesWithClasses();
 193         }
 194
 195         /**
 196          * Get the generators array mapping module names to class names
 197          * @deprecated since 1.21, list of generators is maintained by ApiPageSet
 198          * @return array Array(modulename => classname)
 199          */
 200         public function getGenerators() {
 201                 wfDeprecated( __METHOD__, '1.21' );
 202                 $gens = array();
 203                 foreach ( $this->mModuleMgr->getNamesWithClasses() as $name => $class ) {
 204                         if ( is_subclass_of( $class, 'ApiQueryGeneratorBase' ) ) {
 205                                 $gens[$name] = $class;
 206                         }
 207                 }
 208
 209                 return $gens;
 210         }
 211
 212         /**
 213          * Get whether the specified module is a prop, list or a meta query module
 214          * @deprecated since 1.21, use getModuleManager()->getModuleGroup()
 215          * @param string $moduleName Name of the module to find type for
 216          * @return string|null
 217          */
 218         function getModuleType( $moduleName ) {
 219                 return $this->getModuleManager()->getModuleGroup( $moduleName );
 220         }
 221
 222         /**
 223          * @return ApiFormatRaw|null
 224          */
 225         public function getCustomPrinter() {
 226                 // If &exportnowrap is set, use the raw formatter
 227                 if ( $this->getParameter( 'export' ) &&
 228                         $this->getParameter( 'exportnowrap' )
 229                 ) {
 230                         return new ApiFormatRaw( $this->getMain(),
 231                                 $this->getMain()->createPrinterByName( 'xml' ) );
 232                 } else {
 233                         return null;
 234                 }
 235         }
 236
 237         /**
 238          * Query execution happens in the following steps:
 239          * #1 Create a PageSet object with any pages requested by the user
 240          * #2 If using a generator, execute it to get a new ApiPageSet object
 241          * #3 Instantiate all requested modules.
 242          *    This way the PageSet object will know what shared data is required,
 243          *    and minimize DB calls.
 244          * #4 Output all normalization and redirect resolution information
 245          * #5 Execute all requested modules
 246          */
 247         public function execute() {
 248                 $this->mParams = $this->extractRequestParams();
 249
 250                 if ( $this->mParams['continue'] === null && !$this->mParams['rawcontinue'] ) {
 251                         $this->logFeatureUsage( 'action=query&!rawcontinue&!continue' );
 252                         $this->setWarning(
 253                                 'Formatting of continuation data will be changing soon. ' .
 254                                 'To continue using the current formatting, use the \'rawcontinue\' parameter. ' .
 255                                 'To begin using the new format, pass an empty string for \'continue\' ' .
 256                                 'in the initial query.'
 257                         );
 258                 }
 259
 260                 // Instantiate requested modules
 261                 $allModules = array();
 262                 $this->instantiateModules( $allModules, 'prop' );
 263                 $propModules = array_keys( $allModules );
 264                 $this->instantiateModules( $allModules, 'list' );
 265                 $this->instantiateModules( $allModules, 'meta' );
 266
 267                 // Filter modules based on continue parameter
 268                 list( $generatorDone, $modules ) = $this->getResult()->beginContinuation(
 269                         $this->mParams['continue'], $allModules, $propModules
 270                 );
 271
 272                 if ( !$generatorDone ) {
 273                         // Query modules may optimize data requests through the $this->getPageSet()
 274                         // object by adding extra fields from the page table.
 275                         foreach ( $modules as $module ) {
 276                                 $module->requestExtraData( $this->mPageSet );
 277                         }
 278                         // Populate page/revision information
 279                         $this->mPageSet->execute();
 280                         // Record page information (title, namespace, if exists, etc)
 281                         $this->outputGeneralPageInfo();
 282                 } else {
 283                         $this->mPageSet->executeDryRun();
 284                 }
 285
 286                 $cacheMode = $this->mPageSet->getCacheMode();
 287
 288                 // Execute all unfinished modules
 289                 /** @var $module ApiQueryBase */
 290                 foreach ( $modules as $module ) {
 291                         $params = $module->extractRequestParams();
 292                         $cacheMode = $this->mergeCacheMode(
 293                                 $cacheMode, $module->getCacheMode( $params ) );
 294                         $module->profileIn();
 295                         $module->execute();
 296                         wfRunHooks( 'APIQueryAfterExecute', array( &$module ) );
 297                         $module->profileOut();
 298                 }
 299
 300                 // Set the cache mode
 301                 $this->getMain()->setCacheMode( $cacheMode );
 302
 303                 // Write the continuation data into the result
 304                 $this->getResult()->endContinuation(
 305                         $this->mParams['continue'] === null ? 'raw' : 'standard'
 306                 );
 307         }
 308
 309         /**
 310          * Update a cache mode string, applying the cache mode of a new module to it.
 311          * The cache mode may increase in the level of privacy, but public modules
 312          * added to private data do not decrease the level of privacy.
 313          *
 314          * @param string $cacheMode
 315          * @param string $modCacheMode
 316          * @return string
 317          */
 318         protected function mergeCacheMode( $cacheMode, $modCacheMode ) {
 319                 if ( $modCacheMode === 'anon-public-user-private' ) {
 320                         if ( $cacheMode !== 'private' ) {
 321                                 $cacheMode = 'anon-public-user-private';
 322                         }
 323                 } elseif ( $modCacheMode === 'public' ) {
 324                         // do nothing, if it's public already it will stay public
 325                 } else { // private
 326                         $cacheMode = 'private';
 327                 }
 328
 329                 return $cacheMode;
 330         }
 331
 332         /**
 333          * Create instances of all modules requested by the client
 334          * @param array $modules To append instantiated modules to
 335          * @param string $param Parameter name to read modules from
 336          */
 337         private function instantiateModules( &$modules, $param ) {
 338                 $wasPosted = $this->getRequest()->wasPosted();
 339                 if ( isset( $this->mParams[$param] ) ) {
 340                         foreach ( $this->mParams[$param] as $moduleName ) {
 341                                 $instance = $this->mModuleMgr->getModule( $moduleName, $param );
 342                                 if ( $instance === null ) {
 343                                         ApiBase::dieDebug( __METHOD__, 'Error instantiating module' );
 344                                 }
 345                                 if ( !$wasPosted && $instance->mustBePosted() ) {
 346                                         $this->dieUsageMsgOrDebug( array( 'mustbeposted', $moduleName ) );
 347                                 }
 348                                 // Ignore duplicates. TODO 2.0: die()?
 349                                 if ( !array_key_exists( $moduleName, $modules ) ) {
 350                                         $modules[$moduleName] = $instance;
 351                                 }
 352                         }
 353                 }
 354         }
 355
 356         /**
 357          * Appends an element for each page in the current pageSet with the
 358          * most general information (id, title), plus any title normalizations
 359          * and missing or invalid title/pageids/revids.
 360          */
 361         private function outputGeneralPageInfo() {
 362                 $pageSet = $this->getPageSet();
 363                 $result = $this->getResult();
 364
 365                 // We can't really handle max-result-size failure here, but we need to
 366                 // check anyway in case someone set the limit stupidly low.
 367                 $fit = true;
 368
 369                 $values = $pageSet->getNormalizedTitlesAsResult( $result );
 370                 if ( $values ) {
 371                         $fit = $fit && $result->addValue( 'query', 'normalized', $values );
 372                 }
 373                 $values = $pageSet->getConvertedTitlesAsResult( $result );
 374                 if ( $values ) {
 375                         $fit = $fit && $result->addValue( 'query', 'converted', $values );
 376                 }
 377                 $values = $pageSet->getInterwikiTitlesAsResult( $result, $this->mParams['iwurl'] );
 378                 if ( $values ) {
 379                         $fit = $fit && $result->addValue( 'query', 'interwiki', $values );
 380                 }
 381                 $values = $pageSet->getRedirectTitlesAsResult( $result );
 382                 if ( $values ) {
 383                         $fit = $fit && $result->addValue( 'query', 'redirects', $values );
 384                 }
 385                 $values = $pageSet->getMissingRevisionIDsAsResult( $result );
 386                 if ( $values ) {
 387                         $fit = $fit && $result->addValue( 'query', 'badrevids', $values );
 388                 }
 389
 390                 // Page elements
 391                 $pages = array();
 392
 393                 // Report any missing titles
 394                 foreach ( $pageSet->getMissingTitles() as $fakeId => $title ) {
 395                         $vals = array();
 396                         ApiQueryBase::addTitleInfo( $vals, $title );
 397                         $vals['missing'] = '';
 398                         $pages[$fakeId] = $vals;
 399                 }
 400                 // Report any invalid titles
 401                 foreach ( $pageSet->getInvalidTitles() as $fakeId => $title ) {
 402                         $pages[$fakeId] = array( 'title' => $title, 'invalid' => '' );
 403                 }
 404                 // Report any missing page ids
 405                 foreach ( $pageSet->getMissingPageIDs() as $pageid ) {
 406                         $pages[$pageid] = array(
 407                                 'pageid' => $pageid,
 408                                 'missing' => ''
 409                         );
 410                 }
 411                 // Report special pages
 412                 /** @var $title Title */
 413                 foreach ( $pageSet->getSpecialTitles() as $fakeId => $title ) {
 414                         $vals = array();
 415                         ApiQueryBase::addTitleInfo( $vals, $title );
 416                         $vals['special'] = '';
 417                         if ( $title->isSpecialPage() &&
 418                                 !SpecialPageFactory::exists( $title->getDBkey() )
 419                         ) {
 420                                 $vals['missing'] = '';
 421                         } elseif ( $title->getNamespace() == NS_MEDIA &&
 422                                 !wfFindFile( $title )
 423                         ) {
 424                                 $vals['missing'] = '';
 425                         }
 426                         $pages[$fakeId] = $vals;
 427                 }
 428
 429                 // Output general page information for found titles
 430                 foreach ( $pageSet->getGoodTitles() as $pageid => $title ) {
 431                         $vals = array();
 432                         $vals['pageid'] = $pageid;
 433                         ApiQueryBase::addTitleInfo( $vals, $title );
 434                         $pages[$pageid] = $vals;
 435                 }
 436
 437                 if ( count( $pages ) ) {
 438                         if ( $this->mParams['indexpageids'] ) {
 439                                 $pageIDs = array_keys( $pages );
 440                                 // json treats all map keys as strings - converting to match
 441                                 $pageIDs = array_map( 'strval', $pageIDs );
 442                                 $result->setIndexedTagName( $pageIDs, 'id' );
 443                                 $fit = $fit && $result->addValue( 'query', 'pageids', $pageIDs );
 444                         }
 445
 446                         $result->setIndexedTagName( $pages, 'page' );
 447                         $fit = $fit && $result->addValue( 'query', 'pages', $pages );
 448                 }
 449
 450                 if ( !$fit ) {
 451                         $this->dieUsage(
 452                                 'The value of $wgAPIMaxResultSize on this wiki is ' .
 453                                         'too small to hold basic result information',
 454                                 'badconfig'
 455                         );
 456                 }
 457
 458                 if ( $this->mParams['export'] ) {
 459                         $this->doExport( $pageSet, $result );
 460                 }
 461         }
 462
 463         /**
 464          * This method is called by the generator base when generator in the smart-continue
 465          * mode tries to set 'query-continue' value. ApiQuery stores those values separately
 466          * until the post-processing when it is known if the generation should continue or repeat.
 467          * @deprecated since 1.24
 468          * @param ApiQueryGeneratorBase $module Generator module
 469          * @param string $paramName
 470          * @param mixed $paramValue
 471          * @return bool True if processed, false if this is a legacy continue
 472          */
 473         public function setGeneratorContinue( $module, $paramName, $paramValue ) {
 474                 wfDeprecated( __METHOD__, '1.24' );
 475                 $this->getResult()->setGeneratorContinueParam( $module, $paramName, $paramValue );
 476                 return $this->getParameter( 'continue' ) !== null;
 477         }
 478
 479         /**
 480          * @param ApiPageSet $pageSet Pages to be exported
 481          * @param ApiResult $result Result to output to
 482          */
 483         private function doExport( $pageSet, $result ) {
 484                 $exportTitles = array();
 485                 $titles = $pageSet->getGoodTitles();
 486                 if ( count( $titles ) ) {
 487                         $user = $this->getUser();
 488                         /** @var $title Title */
 489                         foreach ( $titles as $title ) {
 490                                 if ( $title->userCan( 'read', $user ) ) {
 491                                         $exportTitles[] = $title;
 492                                 }
 493                         }
 494                 }
 495
 496                 $exporter = new WikiExporter( $this->getDB() );
 497                 // WikiExporter writes to stdout, so catch its
 498                 // output with an ob
 499                 ob_start();
 500                 $exporter->openStream();
 501                 foreach ( $exportTitles as $title ) {
 502                         $exporter->pageByTitle( $title );
 503                 }
 504                 $exporter->closeStream();
 505                 $exportxml = ob_get_contents();
 506                 ob_end_clean();
 507
 508                 // Don't check the size of exported stuff
 509                 // It's not continuable, so it would cause more
 510                 // problems than it'd solve
 511                 if ( $this->mParams['exportnowrap'] ) {
 512                         $result->reset();
 513                         // Raw formatter will handle this
 514                         $result->addValue( null, 'text', $exportxml, ApiResult::NO_SIZE_CHECK );
 515                         $result->addValue( null, 'mime', 'text/xml', ApiResult::NO_SIZE_CHECK );
 516                 } else {
 517                         $r = array();
 518                         ApiResult::setContent( $r, $exportxml );
 519                         $result->addValue( 'query', 'export', $r, ApiResult::NO_SIZE_CHECK );
 520                 }
 521         }
 522
 523         public function getAllowedParams( $flags = 0 ) {
 524                 $result = array(
 525                         'prop' => array(
 526                                 ApiBase::PARAM_ISMULTI => true,
 527                                 ApiBase::PARAM_TYPE => 'submodule',
 528                         ),
 529                         'list' => array(
 530                                 ApiBase::PARAM_ISMULTI => true,
 531                                 ApiBase::PARAM_TYPE => 'submodule',
 532                         ),
 533                         'meta' => array(
 534                                 ApiBase::PARAM_ISMULTI => true,
 535                                 ApiBase::PARAM_TYPE => 'submodule',
 536                         ),
 537                         'indexpageids' => false,
 538                         'export' => false,
 539                         'exportnowrap' => false,
 540                         'iwurl' => false,
 541                         'continue' => null,
 542                         'rawcontinue' => false,
 543                 );
 544                 if ( $flags ) {
 545                         $result += $this->getPageSet()->getFinalParams( $flags );
 546                 }
 547
 548                 return $result;
 549         }
 550
 551         /**
 552          * Override the parent to generate help messages for all available query modules.
 553          * @deprecated since 1.25
 554          * @return string
 555          */
 556         public function makeHelpMsg() {
 557                 wfDeprecated( __METHOD__, '1.25' );
 558
 559                 // Use parent to make default message for the query module
 560                 $msg = parent::makeHelpMsg();
 561
 562                 $querySeparator = str_repeat( '--- ', 12 );
 563                 $moduleSeparator = str_repeat( '*** ', 14 );
 564                 $msg .= "\n$querySeparator Query: Prop  $querySeparator\n\n";
 565                 $msg .= $this->makeHelpMsgHelper( 'prop' );
 566                 $msg .= "\n$querySeparator Query: List  $querySeparator\n\n";
 567                 $msg .= $this->makeHelpMsgHelper( 'list' );
 568                 $msg .= "\n$querySeparator Query: Meta  $querySeparator\n\n";
 569                 $msg .= $this->makeHelpMsgHelper( 'meta' );
 570                 $msg .= "\n\n$moduleSeparator Modules: continuation  $moduleSeparator\n\n";
 571
 572                 return $msg;
 573         }
 574
 575         /**
 576          * For all modules of a given group, generate help messages and join them together
 577          * @deprecated since 1.25
 578          * @param string $group Module group
 579          * @return string
 580          */
 581         private function makeHelpMsgHelper( $group ) {
 582                 $moduleDescriptions = array();
 583
 584                 $moduleNames = $this->mModuleMgr->getNames( $group );
 585                 sort( $moduleNames );
 586                 foreach ( $moduleNames as $name ) {
 587                         /**
 588                          * @var $module ApiQueryBase
 589                          */
 590                         $module = $this->mModuleMgr->getModule( $name );
 591
 592                         $msg = ApiMain::makeHelpMsgHeader( $module, $group );
 593                         $msg2 = $module->makeHelpMsg();
 594                         if ( $msg2 !== false ) {
 595                                 $msg .= $msg2;
 596                         }
 597                         if ( $module instanceof ApiQueryGeneratorBase ) {
 598                                 $msg .= "Generator:\n  This module may be used as a generator\n";
 599                         }
 600                         $moduleDescriptions[] = $msg;
 601                 }
 602
 603                 return implode( "\n", $moduleDescriptions );
 604         }
 605
 606         public function shouldCheckMaxlag() {
 607                 return true;
 608         }
 609
 610         public function getExamplesMessages() {
 611                 return array(
 612                         'action=query&prop=revisions&meta=siteinfo&' .
 613                                 'titles=Main%20Page&rvprop=user|comment&continue='
 614                                 => 'apihelp-query-example-revisions',
 615                         'action=query&generator=allpages&gapprefix=API/&prop=revisions&continue='
 616                                 => 'apihelp-query-example-allpages',
 617                 );
 618         }
 619
 620         public function getHelpUrls() {
 621                 return array(
 622                         'https://www.mediawiki.org/wiki/API:Query',
 623                         'https://www.mediawiki.org/wiki/API:Meta',
 624                         'https://www.mediawiki.org/wiki/API:Properties',
 625                         'https://www.mediawiki.org/wiki/API:Lists',
 626                 );
 627         }
 628 }