includes/search/SearchEngine.php

   1 <?php
   2 /**
   3  * Basic search engine
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  * @ingroup Search
  22  */
  23
  24 /**
  25  * @defgroup Search Search
  26  */
  27
  28 use MediaWiki\MediaWikiServices;
  29
  30 /**
  31  * Contain a class for special pages
  32  * @ingroup Search
  33  */
  34 abstract class SearchEngine {
  35         const DEFAULT_SORT = 'relevance';
  36
  37         /** @var string */
  38         public $prefix = '';
  39
  40         /** @var int[]|null */
  41         public $namespaces = [ NS_MAIN ];
  42
  43         /** @var int */
  44         protected $limit = 10;
  45
  46         /** @var int */
  47         protected $offset = 0;
  48
  49         /** @var array|string */
  50         protected $searchTerms = [];
  51
  52         /** @var bool */
  53         protected $showSuggestion = true;
  54         private $sort = self::DEFAULT_SORT;
  55
  56         /** @var array Feature values */
  57         protected $features = [];
  58
  59         /** Profile type for completionSearch */
  60         const COMPLETION_PROFILE_TYPE = 'completionSearchProfile';
  61
  62         /** Profile type for query independent ranking features */
  63         const FT_QUERY_INDEP_PROFILE_TYPE = 'fulltextQueryIndepProfile';
  64
  65         /** Integer flag for legalSearchChars: includes all chars allowed in a search query */
  66         const CHARS_ALL = 1;
  67
  68         /** Integer flag for legalSearchChars: includes all chars allowed in a search term */
  69         const CHARS_NO_SYNTAX = 2;
  70
  71         /**
  72          * Perform a full text search query and return a result set.
  73          * If full text searches are not supported or disabled, return null.
  74          *
  75          * As of 1.32 overriding this function is deprecated. It will
  76          * be converted to final in 1.34. Override self::doSearchText().
  77          *
  78          * @param string $term Raw search term
  79          * @return SearchResultSet|Status|null
  80          */
  81         public function searchText( $term ) {
  82                 return $this->maybePaginate( function () use ( $term ) {
  83                         return $this->doSearchText( $term );
  84                 } );
  85         }
  86
  87         /**
  88          * Perform a full text search query and return a result set.
  89          *
  90          * @param string $term Raw search term
  91          * @return SearchResultSet|Status|null
  92          * @since 1.32
  93          */
  94         protected function doSearchText( $term ) {
  95                 return null;
  96         }
  97
  98         /**
  99          * Perform a title search in the article archive.
 100          * NOTE: these results still should be filtered by
 101          * matching against PageArchive, permissions checks etc
 102          * The results returned by this methods are only sugegstions and
 103          * may not end up being shown to the user.
 104          *
 105          * As of 1.32 overriding this function is deprecated. It will
 106          * be converted to final in 1.34. Override self::doSearchArchiveTitle().
 107          *
 108          * @param string $term Raw search term
 109          * @return Status<Title[]>
 110          * @since 1.29
 111          */
 112         public function searchArchiveTitle( $term ) {
 113                 return $this->doSearchArchiveTitle( $term );
 114         }
 115
 116         /**
 117          * Perform a title search in the article archive.
 118          *
 119          * @param string $term Raw search term
 120          * @return Status<Title[]>
 121          * @since 1.32
 122          */
 123         protected function doSearchArchiveTitle( $term ) {
 124                 return Status::newGood( [] );
 125         }
 126
 127         /**
 128          * Perform a title-only search query and return a result set.
 129          * If title searches are not supported or disabled, return null.
 130          * STUB
 131          *
 132          * As of 1.32 overriding this function is deprecated. It will
 133          * be converted to final in 1.34. Override self::doSearchTitle().
 134          *
 135          * @param string $term Raw search term
 136          * @return SearchResultSet|null
 137          */
 138         public function searchTitle( $term ) {
 139                 return $this->maybePaginate( function () use ( $term ) {
 140                         return $this->doSearchTitle( $term );
 141                 } );
 142         }
 143
 144         /**
 145          * Perform a title-only search query and return a result set.
 146          *
 147          * @param string $term Raw search term
 148          * @return SearchResultSet|null
 149          * @since 1.32
 150          */
 151         protected function doSearchTitle( $term ) {
 152                 return null;
 153         }
 154
 155         /**
 156          * Performs an overfetch and shrink operation to determine if
 157          * the next page is available for search engines that do not
 158          * explicitly implement their own pagination.
 159          *
 160          * @param Closure $fn Takes no arguments
 161          * @return SearchResultSet|Status<SearchResultSet>|null Result of calling $fn
 162          */
 163         private function maybePaginate( Closure $fn ) {
 164                 if ( $this instanceof PaginatingSearchEngine ) {
 165                         return $fn();
 166                 }
 167                 $this->limit++;
 168                 try {
 169                         $resultSetOrStatus = $fn();
 170                 } finally {
 171                         $this->limit--;
 172                 }
 173
 174                 $resultSet = null;
 175                 if ( $resultSetOrStatus instanceof SearchResultSet ) {
 176                         $resultSet = $resultSetOrStatus;
 177                 } elseif ( $resultSetOrStatus instanceof Status &&
 178                         $resultSetOrStatus->getValue() instanceof SearchResultSet
 179                 ) {
 180                         $resultSet = $resultSetOrStatus->getValue();
 181                 }
 182                 if ( $resultSet ) {
 183                         $resultSet->shrink( $this->limit );
 184                 }
 185
 186                 return $resultSetOrStatus;
 187         }
 188
 189         /**
 190          * @since 1.18
 191          * @param string $feature
 192          * @return bool
 193          */
 194         public function supports( $feature ) {
 195                 switch ( $feature ) {
 196                         case 'search-update':
 197                                 return true;
 198                         case 'title-suffix-filter':
 199                         default:
 200                                 return false;
 201                 }
 202         }
 203
 204         /**
 205          * Way to pass custom data for engines
 206          * @since 1.18
 207          * @param string $feature
 208          * @param mixed $data
 209          */
 210         public function setFeatureData( $feature, $data ) {
 211                 $this->features[$feature] = $data;
 212         }
 213
 214         /**
 215          * Way to retrieve custom data set by setFeatureData
 216          * or by the engine itself.
 217          * @since 1.29
 218          * @param string $feature feature name
 219          * @return mixed the feature value or null if unset
 220          */
 221         public function getFeatureData( $feature ) {
 222                 return $this->features[$feature] ?? null;
 223         }
 224
 225         /**
 226          * When overridden in derived class, performs database-specific conversions
 227          * on text to be used for searching or updating search index.
 228          * Default implementation does nothing (simply returns $string).
 229          *
 230          * @param string $string String to process
 231          * @return string
 232          */
 233         public function normalizeText( $string ) {
 234                 // Some languages such as Chinese require word segmentation
 235                 return MediaWikiServices::getInstance()->getContentLanguage()->segmentByWord( $string );
 236         }
 237
 238         /**
 239          * Get service class to finding near matches.
 240          * @param Config $config Configuration to use for the matcher.
 241          * @return SearchNearMatcher
 242          */
 243         public function getNearMatcher( Config $config ) {
 244                 return new SearchNearMatcher( $config,
 245                         MediaWikiServices::getInstance()->getContentLanguage() );
 246         }
 247
 248         /**
 249          * Get near matcher for default SearchEngine.
 250          * @return SearchNearMatcher
 251          */
 252         protected static function defaultNearMatcher() {
 253                 $services = MediaWikiServices::getInstance();
 254                 $config = $services->getMainConfig();
 255                 return $services->newSearchEngine()->getNearMatcher( $config );
 256         }
 257
 258         /**
 259          * Get chars legal for search
 260          * @param int $type type of search chars (see self::CHARS_ALL
 261          * and self::CHARS_NO_SYNTAX). Defaults to CHARS_ALL
 262          * @return string
 263          */
 264         public function legalSearchChars( $type = self::CHARS_ALL ) {
 265                 return "A-Za-z_'.0-9\\x80-\\xFF\\-";
 266         }
 267
 268         /**
 269          * Set the maximum number of results to return
 270          * and how many to skip before returning the first.
 271          *
 272          * @param int $limit
 273          * @param int $offset
 274          */
 275         function setLimitOffset( $limit, $offset = 0 ) {
 276                 $this->limit = intval( $limit );
 277                 $this->offset = intval( $offset );
 278         }
 279
 280         /**
 281          * Set which namespaces the search should include.
 282          * Give an array of namespace index numbers.
 283          *
 284          * @param int[]|null $namespaces
 285          */
 286         function setNamespaces( $namespaces ) {
 287                 if ( $namespaces ) {
 288                         // Filter namespaces to only keep valid ones
 289                         $validNs = MediaWikiServices::getInstance()->getSearchEngineConfig()->searchableNamespaces();
 290                         $namespaces = array_filter( $namespaces, function ( $ns ) use( $validNs ) {
 291                                 return $ns < 0 || isset( $validNs[$ns] );
 292                         } );
 293                 } else {
 294                         $namespaces = [];
 295                 }
 296                 $this->namespaces = $namespaces;
 297         }
 298
 299         /**
 300          * Set whether the searcher should try to build a suggestion.  Note: some searchers
 301          * don't support building a suggestion in the first place and others don't respect
 302          * this flag.
 303          *
 304          * @param bool $showSuggestion Should the searcher try to build suggestions
 305          */
 306         function setShowSuggestion( $showSuggestion ) {
 307                 $this->showSuggestion = $showSuggestion;
 308         }
 309
 310         /**
 311          * Get the valid sort directions.  All search engines support 'relevance' but others
 312          * might support more. The default in all implementations must be 'relevance.'
 313          *
 314          * @since 1.25
 315          * @return string[] the valid sort directions for setSort
 316          */
 317         public function getValidSorts() {
 318                 return [ self::DEFAULT_SORT ];
 319         }
 320
 321         /**
 322          * Set the sort direction of the search results. Must be one returned by
 323          * SearchEngine::getValidSorts()
 324          *
 325          * @since 1.25
 326          * @throws InvalidArgumentException
 327          * @param string $sort sort direction for query result
 328          */
 329         public function setSort( $sort ) {
 330                 if ( !in_array( $sort, $this->getValidSorts() ) ) {
 331                         throw new InvalidArgumentException( "Invalid sort: $sort. " .
 332                                 "Must be one of: " . implode( ', ', $this->getValidSorts() ) );
 333                 }
 334                 $this->sort = $sort;
 335         }
 336
 337         /**
 338          * Get the sort direction of the search results
 339          *
 340          * @since 1.25
 341          * @return string
 342          */
 343         public function getSort() {
 344                 return $this->sort;
 345         }
 346
 347         /**
 348          * Parse some common prefixes: all (search everything)
 349          * or namespace names and set the list of namespaces
 350          * of this class accordingly.
 351          *
 352          * @deprecated since 1.32; should be handled internally by the search engine
 353          * @param string $query
 354          * @return string
 355          */
 356         function replacePrefixes( $query ) {
 357                 return $query;
 358         }
 359
 360         /**
 361          * Parse some common prefixes: all (search everything)
 362          * or namespace names
 363          *
 364          * @param string $query
 365          * @param bool $withAllKeyword activate support of the "all:" keyword and its
 366          * translations to activate searching on all namespaces.
 367          * @param bool $withPrefixSearchExtractNamespaceHook call the PrefixSearchExtractNamespace hook
 368          *  if classic namespace identification did not match.
 369          * @return false|array false if no namespace was extracted, an array
 370          * with the parsed query at index 0 and an array of namespaces at index
 371          * 1 (or null for all namespaces).
 372          * @throws FatalError
 373          * @throws MWException
 374          */
 375         public static function parseNamespacePrefixes(
 376                 $query,
 377                 $withAllKeyword = true,
 378                 $withPrefixSearchExtractNamespaceHook = false
 379         ) {
 380                 $parsed = $query;
 381                 if ( strpos( $query, ':' ) === false ) { // nothing to do
 382                         return false;
 383                 }
 384                 $extractedNamespace = null;
 385
 386                 $allQuery = false;
 387                 if ( $withAllKeyword ) {
 388                         $allkeywords = [];
 389
 390                         $allkeywords[] = wfMessage( 'searchall' )->inContentLanguage()->text() . ":";
 391                         // force all: so that we have a common syntax for all the wikis
 392                         if ( !in_array( 'all:', $allkeywords ) ) {
 393                                 $allkeywords[] = 'all:';
 394                         }
 395
 396                         foreach ( $allkeywords as $kw ) {
 397                                 if ( strncmp( $query, $kw, strlen( $kw ) ) == 0 ) {
 398                                         $extractedNamespace = null;
 399                                         $parsed = substr( $query, strlen( $kw ) );
 400                                         $allQuery = true;
 401                                         break;
 402                                 }
 403                         }
 404                 }
 405
 406                 if ( !$allQuery && strpos( $query, ':' ) !== false ) {
 407                         $prefix = str_replace( ' ', '_', substr( $query, 0, strpos( $query, ':' ) ) );
 408                         $index = MediaWikiServices::getInstance()->getContentLanguage()->getNsIndex( $prefix );
 409                         if ( $index !== false ) {
 410                                 $extractedNamespace = [ $index ];
 411                                 $parsed = substr( $query, strlen( $prefix ) + 1 );
 412                         } elseif ( $withPrefixSearchExtractNamespaceHook ) {
 413                                 $hookNamespaces = [ NS_MAIN ];
 414                                 $hookQuery = $query;
 415                                 Hooks::run( 'PrefixSearchExtractNamespace', [ &$hookNamespaces, &$hookQuery ] );
 416                                 if ( $hookQuery !== $query ) {
 417                                         $parsed = $hookQuery;
 418                                         $extractedNamespace = $hookNamespaces;
 419                                 } else {
 420                                         return false;
 421                                 }
 422                         } else {
 423                                 return false;
 424                         }
 425                 }
 426
 427                 return [ $parsed, $extractedNamespace ];
 428         }
 429
 430         /**
 431          * Find snippet highlight settings for all users
 432          * @return array Contextlines, contextchars
 433          */
 434         public static function userHighlightPrefs() {
 435                 $contextlines = 2; // Hardcode this. Old defaults sucked. :)
 436                 $contextchars = 75; // same as above.... :P
 437                 return [ $contextlines, $contextchars ];
 438         }
 439
 440         /**
 441          * Create or update the search index record for the given page.
 442          * Title and text should be pre-processed.
 443          * STUB
 444          *
 445          * @param int $id
 446          * @param string $title
 447          * @param string $text
 448          */
 449         function update( $id, $title, $text ) {
 450                 // no-op
 451         }
 452
 453         /**
 454          * Update a search index record's title only.
 455          * Title should be pre-processed.
 456          * STUB
 457          *
 458          * @param int $id
 459          * @param string $title
 460          */
 461         function updateTitle( $id, $title ) {
 462                 // no-op
 463         }
 464
 465         /**
 466          * Delete an indexed page
 467          * Title should be pre-processed.
 468          * STUB
 469          *
 470          * @param int $id Page id that was deleted
 471          * @param string $title Title of page that was deleted
 472          */
 473         function delete( $id, $title ) {
 474                 // no-op
 475         }
 476
 477         /**
 478          * Get the raw text for updating the index from a content object
 479          * Nicer search backends could possibly do something cooler than
 480          * just returning raw text
 481          *
 482          * @todo This isn't ideal, we'd really like to have content-specific handling here
 483          * @param Title $t Title we're indexing
 484          * @param Content|null $c Content of the page to index
 485          * @return string
 486          */
 487         public function getTextFromContent( Title $t, Content $c = null ) {
 488                 return $c ? $c->getTextForSearchIndex() : '';
 489         }
 490
 491         /**
 492          * If an implementation of SearchEngine handles all of its own text processing
 493          * in getTextFromContent() and doesn't require SearchUpdate::updateText()'s
 494          * rather silly handling, it should return true here instead.
 495          *
 496          * @return bool
 497          */
 498         public function textAlreadyUpdatedForIndex() {
 499                 return false;
 500         }
 501
 502         /**
 503          * Makes search simple string if it was namespaced.
 504          * Sets namespaces of the search to namespaces extracted from string.
 505          * @param string $search
 506          * @return string Simplified search string
 507          */
 508         protected function normalizeNamespaces( $search ) {
 509                 $queryAndNs = self::parseNamespacePrefixes( $search, false, true );
 510                 if ( $queryAndNs !== false ) {
 511                         $this->setNamespaces( $queryAndNs[1] );
 512                         return $queryAndNs[0];
 513                 }
 514                 return $search;
 515         }
 516
 517         /**
 518          * Perform an overfetch of completion search results. This allows
 519          * determining if another page of results is available.
 520          *
 521          * @param string $search
 522          * @return SearchSuggestionSet
 523          */
 524         protected function completionSearchBackendOverfetch( $search ) {
 525                 $this->limit++;
 526                 try {
 527                         return $this->completionSearchBackend( $search );
 528                 } finally {
 529                         $this->limit--;
 530                 }
 531         }
 532
 533         /**
 534          * Perform a completion search.
 535          * Does not resolve namespaces and does not check variants.
 536          * Search engine implementations may want to override this function.
 537          * @param string $search
 538          * @return SearchSuggestionSet
 539          */
 540         protected function completionSearchBackend( $search ) {
 541                 $results = [];
 542
 543                 $search = trim( $search );
 544
 545                 if ( !in_array( NS_SPECIAL, $this->namespaces ) && // We do not run hook on Special: search
 546                          !Hooks::run( 'PrefixSearchBackend',
 547                                 [ $this->namespaces, $search, $this->limit, &$results, $this->offset ]
 548                 ) ) {
 549                         // False means hook worked.
 550                         // FIXME: Yes, the API is weird. That's why it is going to be deprecated.
 551
 552                         return SearchSuggestionSet::fromStrings( $results );
 553                 } else {
 554                         // Hook did not do the job, use default simple search
 555                         $results = $this->simplePrefixSearch( $search );
 556                         return SearchSuggestionSet::fromTitles( $results );
 557                 }
 558         }
 559
 560         /**
 561          * Perform a completion search.
 562          * @param string $search
 563          * @return SearchSuggestionSet
 564          */
 565         public function completionSearch( $search ) {
 566                 if ( trim( $search ) === '' ) {
 567                         return SearchSuggestionSet::emptySuggestionSet(); // Return empty result
 568                 }
 569                 $search = $this->normalizeNamespaces( $search );
 570                 $suggestions = $this->completionSearchBackendOverfetch( $search );
 571                 return $this->processCompletionResults( $search, $suggestions );
 572         }
 573
 574         /**
 575          * Perform a completion search with variants.
 576          * @param string $search
 577          * @return SearchSuggestionSet
 578          */
 579         public function completionSearchWithVariants( $search ) {
 580                 if ( trim( $search ) === '' ) {
 581                         return SearchSuggestionSet::emptySuggestionSet(); // Return empty result
 582                 }
 583                 $search = $this->normalizeNamespaces( $search );
 584
 585                 $results = $this->completionSearchBackendOverfetch( $search );
 586                 $fallbackLimit = 1 + $this->limit - $results->getSize();
 587                 if ( $fallbackLimit > 0 ) {
 588                         $fallbackSearches = MediaWikiServices::getInstance()->getContentLanguage()->
 589                                 autoConvertToAllVariants( $search );
 590                         $fallbackSearches = array_diff( array_unique( $fallbackSearches ), [ $search ] );
 591
 592                         foreach ( $fallbackSearches as $fbs ) {
 593                                 $this->setLimitOffset( $fallbackLimit );
 594                                 $fallbackSearchResult = $this->completionSearch( $fbs );
 595                                 $results->appendAll( $fallbackSearchResult );
 596                                 $fallbackLimit -= $fallbackSearchResult->getSize();
 597                                 if ( $fallbackLimit <= 0 ) {
 598                                         break;
 599                                 }
 600                         }
 601                 }
 602                 return $this->processCompletionResults( $search, $results );
 603         }
 604
 605         /**
 606          * Extract titles from completion results
 607          * @param SearchSuggestionSet $completionResults
 608          * @return Title[]
 609          */
 610         public function extractTitles( SearchSuggestionSet $completionResults ) {
 611                 return $completionResults->map( function ( SearchSuggestion $sugg ) {
 612                         return $sugg->getSuggestedTitle();
 613                 } );
 614         }
 615
 616         /**
 617          * Process completion search results.
 618          * Resolves the titles and rescores.
 619          * @param string $search
 620          * @param SearchSuggestionSet $suggestions
 621          * @return SearchSuggestionSet
 622          */
 623         protected function processCompletionResults( $search, SearchSuggestionSet $suggestions ) {
 624                 // We over-fetched to determine pagination. Shrink back down if we have extra results
 625                 // and mark if pagination is possible
 626                 $suggestions->shrink( $this->limit );
 627
 628                 $search = trim( $search );
 629                 // preload the titles with LinkBatch
 630                 $lb = new LinkBatch( $suggestions->map( function ( SearchSuggestion $sugg ) {
 631                         return $sugg->getSuggestedTitle();
 632                 } ) );
 633                 $lb->setCaller( __METHOD__ );
 634                 $lb->execute();
 635
 636                 $diff = $suggestions->filter( function ( SearchSuggestion $sugg ) {
 637                         return $sugg->getSuggestedTitle()->isKnown();
 638                 } );
 639                 if ( $diff > 0 ) {
 640                         MediaWikiServices::getInstance()->getStatsdDataFactory()
 641                                 ->updateCount( 'search.completion.missing', $diff );
 642                 }
 643
 644                 $results = $suggestions->map( function ( SearchSuggestion $sugg ) {
 645                         return $sugg->getSuggestedTitle()->getPrefixedText();
 646                 } );
 647
 648                 if ( $this->offset === 0 ) {
 649                         // Rescore results with an exact title match
 650                         // NOTE: in some cases like cross-namespace redirects
 651                         // (frequently used as shortcuts e.g. WP:WP on huwiki) some
 652                         // backends like Cirrus will return no results. We should still
 653                         // try an exact title match to workaround this limitation
 654                         $rescorer = new SearchExactMatchRescorer();
 655                         $rescoredResults = $rescorer->rescore( $search, $this->namespaces, $results, $this->limit );
 656                 } else {
 657                         // No need to rescore if offset is not 0
 658                         // The exact match must have been returned at position 0
 659                         // if it existed.
 660                         $rescoredResults = $results;
 661                 }
 662
 663                 if ( count( $rescoredResults ) > 0 ) {
 664                         $found = array_search( $rescoredResults[0], $results );
 665                         if ( $found === false ) {
 666                                 // If the first result is not in the previous array it
 667                                 // means that we found a new exact match
 668                                 $exactMatch = SearchSuggestion::fromTitle( 0, Title::newFromText( $rescoredResults[0] ) );
 669                                 $suggestions->prepend( $exactMatch );
 670                                 $suggestions->shrink( $this->limit );
 671                         } else {
 672                                 // if the first result is not the same we need to rescore
 673                                 if ( $found > 0 ) {
 674                                         $suggestions->rescore( $found );
 675                                 }
 676                         }
 677                 }
 678
 679                 return $suggestions;
 680         }
 681
 682         /**
 683          * Simple prefix search for subpages.
 684          * @param string $search
 685          * @return Title[]
 686          */
 687         public function defaultPrefixSearch( $search ) {
 688                 if ( trim( $search ) === '' ) {
 689                         return [];
 690                 }
 691
 692                 $search = $this->normalizeNamespaces( $search );
 693                 return $this->simplePrefixSearch( $search );
 694         }
 695
 696         /**
 697          * Call out to simple search backend.
 698          * Defaults to TitlePrefixSearch.
 699          * @param string $search
 700          * @return Title[]
 701          */
 702         protected function simplePrefixSearch( $search ) {
 703                 // Use default database prefix search
 704                 $backend = new TitlePrefixSearch;
 705                 return $backend->defaultSearchBackend( $this->namespaces, $search, $this->limit, $this->offset );
 706         }
 707
 708         /**
 709          * Get a list of supported profiles.
 710          * Some search engine implementations may expose specific profiles to fine-tune
 711          * its behaviors.
 712          * The profile can be passed as a feature data with setFeatureData( $profileType, $profileName )
 713          * The array returned by this function contains the following keys:
 714          * - name: the profile name to use with setFeatureData
 715          * - desc-message: the i18n description
 716          * - default: set to true if this profile is the default
 717          *
 718          * @since 1.28
 719          * @param string $profileType the type of profiles
 720          * @param User|null $user the user requesting the list of profiles
 721          * @return array|null the list of profiles or null if none available
 722          */
 723         public function getProfiles( $profileType, User $user = null ) {
 724                 return null;
 725         }
 726
 727         /**
 728          * Create a search field definition.
 729          * Specific search engines should override this method to create search fields.
 730          * @param string $name
 731          * @param string $type One of the types in SearchIndexField::INDEX_TYPE_*
 732          * @return SearchIndexField
 733          * @since 1.28
 734          */
 735         public function makeSearchFieldMapping( $name, $type ) {
 736                 return new NullIndexField();
 737         }
 738
 739         /**
 740          * Get fields for search index
 741          * @since 1.28
 742          * @return SearchIndexField[] Index field definitions for all content handlers
 743          */
 744         public function getSearchIndexFields() {
 745                 $models = ContentHandler::getContentModels();
 746                 $fields = [];
 747                 $seenHandlers = new SplObjectStorage();
 748                 foreach ( $models as $model ) {
 749                         try {
 750                                 $handler = ContentHandler::getForModelID( $model );
 751                         }
 752                         catch ( MWUnknownContentModelException $e ) {
 753                                 // If we can find no handler, ignore it
 754                                 continue;
 755                         }
 756                         // Several models can have the same handler, so avoid processing it repeatedly
 757                         if ( $seenHandlers->contains( $handler ) ) {
 758                                 // We already did this one
 759                                 continue;
 760                         }
 761                         $seenHandlers->attach( $handler );
 762                         $handlerFields = $handler->getFieldsForSearchIndex( $this );
 763                         foreach ( $handlerFields as $fieldName => $fieldData ) {
 764                                 if ( empty( $fields[$fieldName] ) ) {
 765                                         $fields[$fieldName] = $fieldData;
 766                                 } else {
 767                                         // TODO: do we allow some clashes with the same type or reject all of them?
 768                                         $mergeDef = $fields[$fieldName]->merge( $fieldData );
 769                                         if ( !$mergeDef ) {
 770                                                 throw new InvalidArgumentException( "Duplicate field $fieldName for model $model" );
 771                                         }
 772                                         $fields[$fieldName] = $mergeDef;
 773                                 }
 774                         }
 775                 }
 776                 // Hook to allow extensions to produce search mapping fields
 777                 Hooks::run( 'SearchIndexFields', [ &$fields, $this ] );
 778                 return $fields;
 779         }
 780
 781         /**
 782          * Augment search results with extra data.
 783          *
 784          * @param SearchResultSet $resultSet
 785          */
 786         public function augmentSearchResults( SearchResultSet $resultSet ) {
 787                 $setAugmentors = [];
 788                 $rowAugmentors = [];
 789                 Hooks::run( "SearchResultsAugment", [ &$setAugmentors, &$rowAugmentors ] );
 790                 if ( !$setAugmentors && !$rowAugmentors ) {
 791                         // We're done here
 792                         return;
 793                 }
 794
 795                 // Convert row augmentors to set augmentor
 796                 foreach ( $rowAugmentors as $name => $row ) {
 797                         if ( isset( $setAugmentors[$name] ) ) {
 798                                 throw new InvalidArgumentException( "Both row and set augmentors are defined for $name" );
 799                         }
 800                         $setAugmentors[$name] = new PerRowAugmentor( $row );
 801                 }
 802
 803                 foreach ( $setAugmentors as $name => $augmentor ) {
 804                         $data = $augmentor->augmentAll( $resultSet );
 805                         if ( $data ) {
 806                                 $resultSet->setAugmentedData( $name, $data );
 807                         }
 808                 }
 809         }
 810 }