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         /** @var string */
  36         public $prefix = '';
  37
  38         /** @var int[]|null */
  39         public $namespaces = [ NS_MAIN ];
  40
  41         /** @var int */
  42         protected $limit = 10;
  43
  44         /** @var int */
  45         protected $offset = 0;
  46
  47         /** @var array|string */
  48         protected $searchTerms = [];
  49
  50         /** @var bool */
  51         protected $showSuggestion = true;
  52         private $sort = 'relevance';
  53
  54         /** @var array Feature values */
  55         protected $features = [];
  56
  57         /** @const string profile type for completionSearch */
  58         const COMPLETION_PROFILE_TYPE = 'completionSearchProfile';
  59
  60         /** @const string profile type for query independent ranking features */
  61         const FT_QUERY_INDEP_PROFILE_TYPE = 'fulltextQueryIndepProfile';
  62
  63         /** @const int flag for legalSearchChars: includes all chars allowed in a search query */
  64         const CHARS_ALL = 1;
  65
  66         /** @const int flag for legalSearchChars: includes all chars allowed in a search term */
  67         const CHARS_NO_SYNTAX = 2;
  68
  69         /**
  70          * Perform a full text search query and return a result set.
  71          * If full text searches are not supported or disabled, return null.
  72          * STUB
  73          *
  74          * @param string $term Raw search term
  75          * @return SearchResultSet|Status|null
  76          */
  77         function searchText( $term ) {
  78                 return null;
  79         }
  80
  81         /**
  82          * Perform a title search in the article archive.
  83          * NOTE: these results still should be filtered by
  84          * matching against PageArchive, permissions checks etc
  85          * The results returned by this methods are only sugegstions and
  86          * may not end up being shown to the user.
  87          *
  88          * @param string $term Raw search term
  89          * @return Status<Title[]>
  90          * @since 1.29
  91          */
  92         function searchArchiveTitle( $term ) {
  93                 return Status::newGood( [] );
  94         }
  95
  96         /**
  97          * Perform a title-only search query and return a result set.
  98          * If title searches are not supported or disabled, return null.
  99          * STUB
 100          *
 101          * @param string $term Raw search term
 102          * @return SearchResultSet|null
 103          */
 104         function searchTitle( $term ) {
 105                 return null;
 106         }
 107
 108         /**
 109          * @since 1.18
 110          * @param string $feature
 111          * @return bool
 112          */
 113         public function supports( $feature ) {
 114                 switch ( $feature ) {
 115                 case 'search-update':
 116                         return true;
 117                 case 'title-suffix-filter':
 118                 default:
 119                         return false;
 120                 }
 121         }
 122
 123         /**
 124          * Way to pass custom data for engines
 125          * @since 1.18
 126          * @param string $feature
 127          * @param mixed $data
 128          */
 129         public function setFeatureData( $feature, $data ) {
 130                 $this->features[$feature] = $data;
 131         }
 132
 133         /**
 134          * Way to retrieve custom data set by setFeatureData
 135          * or by the engine itself.
 136          * @since 1.29
 137          * @param string $feature feature name
 138          * @return mixed the feature value or null if unset
 139          */
 140         public function getFeatureData( $feature ) {
 141                 if ( isset( $this->features[$feature] ) ) {
 142                         return $this->features[$feature];
 143                 }
 144                 return null;
 145         }
 146
 147         /**
 148          * When overridden in derived class, performs database-specific conversions
 149          * on text to be used for searching or updating search index.
 150          * Default implementation does nothing (simply returns $string).
 151          *
 152          * @param string $string String to process
 153          * @return string
 154          */
 155         public function normalizeText( $string ) {
 156                 global $wgContLang;
 157
 158                 // Some languages such as Chinese require word segmentation
 159                 return $wgContLang->segmentByWord( $string );
 160         }
 161
 162         /**
 163          * Transform search term in cases when parts of the query came as different
 164          * GET params (when supported), e.g. for prefix queries:
 165          * search=test&prefix=Main_Page/Archive -> test prefix:Main Page/Archive
 166          * @param string $term
 167          * @return string
 168          */
 169         public function transformSearchTerm( $term ) {
 170                 return $term;
 171         }
 172
 173         /**
 174          * Get service class to finding near matches.
 175          * @param Config $config Configuration to use for the matcher.
 176          * @return SearchNearMatcher
 177          */
 178         public function getNearMatcher( Config $config ) {
 179                 global $wgContLang;
 180                 return new SearchNearMatcher( $config, $wgContLang );
 181         }
 182
 183         /**
 184          * Get near matcher for default SearchEngine.
 185          * @return SearchNearMatcher
 186          */
 187         protected static function defaultNearMatcher() {
 188                 $config = MediaWikiServices::getInstance()->getMainConfig();
 189                 return MediaWikiServices::getInstance()->newSearchEngine()->getNearMatcher( $config );
 190         }
 191
 192         /**
 193          * If an exact title match can be found, or a very slightly close match,
 194          * return the title. If no match, returns NULL.
 195          * @deprecated since 1.27; Use SearchEngine::getNearMatcher()
 196          * @param string $searchterm
 197          * @return Title
 198          */
 199         public static function getNearMatch( $searchterm ) {
 200                 return static::defaultNearMatcher()->getNearMatch( $searchterm );
 201         }
 202
 203         /**
 204          * Do a near match (see SearchEngine::getNearMatch) and wrap it into a
 205          * SearchResultSet.
 206          * @deprecated since 1.27; Use SearchEngine::getNearMatcher()
 207          * @param string $searchterm
 208          * @return SearchResultSet
 209          */
 210         public static function getNearMatchResultSet( $searchterm ) {
 211                 return static::defaultNearMatcher()->getNearMatchResultSet( $searchterm );
 212         }
 213
 214         /**
 215          * Get chars legal for search
 216          * NOTE: usage as static is deprecated and preserved only as BC measure
 217          * @param int $type type of search chars (see self::CHARS_ALL
 218          * and self::CHARS_NO_SYNTAX). Defaults to CHARS_ALL
 219          * @return string
 220          */
 221         public static function legalSearchChars( $type = self::CHARS_ALL ) {
 222                 return "A-Za-z_'.0-9\\x80-\\xFF\\-";
 223         }
 224
 225         /**
 226          * Set the maximum number of results to return
 227          * and how many to skip before returning the first.
 228          *
 229          * @param int $limit
 230          * @param int $offset
 231          */
 232         function setLimitOffset( $limit, $offset = 0 ) {
 233                 $this->limit = intval( $limit );
 234                 $this->offset = intval( $offset );
 235         }
 236
 237         /**
 238          * Set which namespaces the search should include.
 239          * Give an array of namespace index numbers.
 240          *
 241          * @param int[]|null $namespaces
 242          */
 243         function setNamespaces( $namespaces ) {
 244                 if ( $namespaces ) {
 245                         // Filter namespaces to only keep valid ones
 246                         $validNs = $this->searchableNamespaces();
 247                         $namespaces = array_filter( $namespaces, function ( $ns ) use( $validNs ) {
 248                                 return $ns < 0 || isset( $validNs[$ns] );
 249                         } );
 250                 } else {
 251                         $namespaces = [];
 252                 }
 253                 $this->namespaces = $namespaces;
 254         }
 255
 256         /**
 257          * Set whether the searcher should try to build a suggestion.  Note: some searchers
 258          * don't support building a suggestion in the first place and others don't respect
 259          * this flag.
 260          *
 261          * @param bool $showSuggestion Should the searcher try to build suggestions
 262          */
 263         function setShowSuggestion( $showSuggestion ) {
 264                 $this->showSuggestion = $showSuggestion;
 265         }
 266
 267         /**
 268          * Get the valid sort directions.  All search engines support 'relevance' but others
 269          * might support more. The default in all implementations should be 'relevance.'
 270          *
 271          * @since 1.25
 272          * @return string[] the valid sort directions for setSort
 273          */
 274         public function getValidSorts() {
 275                 return [ 'relevance' ];
 276         }
 277
 278         /**
 279          * Set the sort direction of the search results. Must be one returned by
 280          * SearchEngine::getValidSorts()
 281          *
 282          * @since 1.25
 283          * @throws InvalidArgumentException
 284          * @param string $sort sort direction for query result
 285          */
 286         public function setSort( $sort ) {
 287                 if ( !in_array( $sort, $this->getValidSorts() ) ) {
 288                         throw new InvalidArgumentException( "Invalid sort: $sort. " .
 289                                 "Must be one of: " . implode( ', ', $this->getValidSorts() ) );
 290                 }
 291                 $this->sort = $sort;
 292         }
 293
 294         /**
 295          * Get the sort direction of the search results
 296          *
 297          * @since 1.25
 298          * @return string
 299          */
 300         public function getSort() {
 301                 return $this->sort;
 302         }
 303
 304         /**
 305          * Parse some common prefixes: all (search everything)
 306          * or namespace names and set the list of namespaces
 307          * of this class accordingly.
 308          *
 309          * @param string $query
 310          * @return string
 311          */
 312         function replacePrefixes( $query ) {
 313                 $queryAndNs = self::parseNamespacePrefixes( $query );
 314                 if ( $queryAndNs === false ) {
 315                         return $query;
 316                 }
 317                 $this->namespaces = $queryAndNs[1];
 318                 return $queryAndNs[0];
 319         }
 320
 321         /**
 322          * Parse some common prefixes: all (search everything)
 323          * or namespace names
 324          *
 325          * @param string $query
 326          * @return false|array false if no namespace was extracted, an array
 327          * with the parsed query at index 0 and an array of namespaces at index
 328          * 1 (or null for all namespaces).
 329          */
 330         public static function parseNamespacePrefixes( $query ) {
 331                 global $wgContLang;
 332
 333                 $parsed = $query;
 334                 if ( strpos( $query, ':' ) === false ) { // nothing to do
 335                         return false;
 336                 }
 337                 $extractedNamespace = null;
 338
 339                 $allkeyword = wfMessage( 'searchall' )->inContentLanguage()->text() . ":";
 340                 if ( strncmp( $query, $allkeyword, strlen( $allkeyword ) ) == 0 ) {
 341                         $extractedNamespace = null;
 342                         $parsed = substr( $query, strlen( $allkeyword ) );
 343                 } elseif ( strpos( $query, ':' ) !== false ) {
 344                         // TODO: should we unify with PrefixSearch::extractNamespace ?
 345                         $prefix = str_replace( ' ', '_', substr( $query, 0, strpos( $query, ':' ) ) );
 346                         $index = $wgContLang->getNsIndex( $prefix );
 347                         if ( $index !== false ) {
 348                                 $extractedNamespace = [ $index ];
 349                                 $parsed = substr( $query, strlen( $prefix ) + 1 );
 350                         } else {
 351                                 return false;
 352                         }
 353                 }
 354
 355                 if ( trim( $parsed ) == '' ) {
 356                         $parsed = $query; // prefix was the whole query
 357                 }
 358
 359                 return [ $parsed, $extractedNamespace ];
 360         }
 361
 362         /**
 363          * Find snippet highlight settings for all users
 364          * @return array Contextlines, contextchars
 365          */
 366         public static function userHighlightPrefs() {
 367                 $contextlines = 2; // Hardcode this. Old defaults sucked. :)
 368                 $contextchars = 75; // same as above.... :P
 369                 return [ $contextlines, $contextchars ];
 370         }
 371
 372         /**
 373          * Create or update the search index record for the given page.
 374          * Title and text should be pre-processed.
 375          * STUB
 376          *
 377          * @param int $id
 378          * @param string $title
 379          * @param string $text
 380          */
 381         function update( $id, $title, $text ) {
 382                 // no-op
 383         }
 384
 385         /**
 386          * Update a search index record's title only.
 387          * Title should be pre-processed.
 388          * STUB
 389          *
 390          * @param int $id
 391          * @param string $title
 392          */
 393         function updateTitle( $id, $title ) {
 394                 // no-op
 395         }
 396
 397         /**
 398          * Delete an indexed page
 399          * Title should be pre-processed.
 400          * STUB
 401          *
 402          * @param int $id Page id that was deleted
 403          * @param string $title Title of page that was deleted
 404          */
 405         function delete( $id, $title ) {
 406                 // no-op
 407         }
 408
 409         /**
 410          * Get OpenSearch suggestion template
 411          *
 412          * @deprecated since 1.25
 413          * @return string
 414          */
 415         public static function getOpenSearchTemplate() {
 416                 wfDeprecated( __METHOD__, '1.25' );
 417                 return ApiOpenSearch::getOpenSearchTemplate( 'application/x-suggestions+json' );
 418         }
 419
 420         /**
 421          * Get the raw text for updating the index from a content object
 422          * Nicer search backends could possibly do something cooler than
 423          * just returning raw text
 424          *
 425          * @todo This isn't ideal, we'd really like to have content-specific handling here
 426          * @param Title $t Title we're indexing
 427          * @param Content $c Content of the page to index
 428          * @return string
 429          */
 430         public function getTextFromContent( Title $t, Content $c = null ) {
 431                 return $c ? $c->getTextForSearchIndex() : '';
 432         }
 433
 434         /**
 435          * If an implementation of SearchEngine handles all of its own text processing
 436          * in getTextFromContent() and doesn't require SearchUpdate::updateText()'s
 437          * rather silly handling, it should return true here instead.
 438          *
 439          * @return bool
 440          */
 441         public function textAlreadyUpdatedForIndex() {
 442                 return false;
 443         }
 444
 445         /**
 446          * Makes search simple string if it was namespaced.
 447          * Sets namespaces of the search to namespaces extracted from string.
 448          * @param string $search
 449          * @return string Simplified search string
 450          */
 451         protected function normalizeNamespaces( $search ) {
 452                 // Find a Title which is not an interwiki and is in NS_MAIN
 453                 $title = Title::newFromText( $search );
 454                 $ns = $this->namespaces;
 455                 if ( $title && !$title->isExternal() ) {
 456                         $ns = [ $title->getNamespace() ];
 457                         $search = $title->getText();
 458                         if ( $ns[0] == NS_MAIN ) {
 459                                 $ns = $this->namespaces; // no explicit prefix, use default namespaces
 460                                 Hooks::run( 'PrefixSearchExtractNamespace', [ &$ns, &$search ] );
 461                         }
 462                 } else {
 463                         $title = Title::newFromText( $search . 'Dummy' );
 464                         if ( $title && $title->getText() == 'Dummy'
 465                                         && $title->getNamespace() != NS_MAIN
 466                                         && !$title->isExternal()
 467                         ) {
 468                                 $ns = [ $title->getNamespace() ];
 469                                 $search = '';
 470                         } else {
 471                                 Hooks::run( 'PrefixSearchExtractNamespace', [ &$ns, &$search ] );
 472                         }
 473                 }
 474
 475                 $ns = array_map( function ( $space ) {
 476                         return $space == NS_MEDIA ? NS_FILE : $space;
 477                 }, $ns );
 478
 479                 $this->setNamespaces( $ns );
 480                 return $search;
 481         }
 482
 483         /**
 484          * Perform a completion search.
 485          * Does not resolve namespaces and does not check variants.
 486          * Search engine implementations may want to override this function.
 487          * @param string $search
 488          * @return SearchSuggestionSet
 489          */
 490         protected function completionSearchBackend( $search ) {
 491                 $results = [];
 492
 493                 $search = trim( $search );
 494
 495                 if ( !in_array( NS_SPECIAL, $this->namespaces ) && // We do not run hook on Special: search
 496                          !Hooks::run( 'PrefixSearchBackend',
 497                                 [ $this->namespaces, $search, $this->limit, &$results, $this->offset ]
 498                 ) ) {
 499                         // False means hook worked.
 500                         // FIXME: Yes, the API is weird. That's why it is going to be deprecated.
 501
 502                         return SearchSuggestionSet::fromStrings( $results );
 503                 } else {
 504                         // Hook did not do the job, use default simple search
 505                         $results = $this->simplePrefixSearch( $search );
 506                         return SearchSuggestionSet::fromTitles( $results );
 507                 }
 508         }
 509
 510         /**
 511          * Perform a completion search.
 512          * @param string $search
 513          * @return SearchSuggestionSet
 514          */
 515         public function completionSearch( $search ) {
 516                 if ( trim( $search ) === '' ) {
 517                         return SearchSuggestionSet::emptySuggestionSet(); // Return empty result
 518                 }
 519                 $search = $this->normalizeNamespaces( $search );
 520                 return $this->processCompletionResults( $search, $this->completionSearchBackend( $search ) );
 521         }
 522
 523         /**
 524          * Perform a completion search with variants.
 525          * @param string $search
 526          * @return SearchSuggestionSet
 527          */
 528         public function completionSearchWithVariants( $search ) {
 529                 if ( trim( $search ) === '' ) {
 530                         return SearchSuggestionSet::emptySuggestionSet(); // Return empty result
 531                 }
 532                 $search = $this->normalizeNamespaces( $search );
 533
 534                 $results = $this->completionSearchBackend( $search );
 535                 $fallbackLimit = $this->limit - $results->getSize();
 536                 if ( $fallbackLimit > 0 ) {
 537                         global $wgContLang;
 538
 539                         $fallbackSearches = $wgContLang->autoConvertToAllVariants( $search );
 540                         $fallbackSearches = array_diff( array_unique( $fallbackSearches ), [ $search ] );
 541
 542                         foreach ( $fallbackSearches as $fbs ) {
 543                                 $this->setLimitOffset( $fallbackLimit );
 544                                 $fallbackSearchResult = $this->completionSearch( $fbs );
 545                                 $results->appendAll( $fallbackSearchResult );
 546                                 $fallbackLimit -= count( $fallbackSearchResult );
 547                                 if ( $fallbackLimit <= 0 ) {
 548                                         break;
 549                                 }
 550                         }
 551                 }
 552                 return $this->processCompletionResults( $search, $results );
 553         }
 554
 555         /**
 556          * Extract titles from completion results
 557          * @param SearchSuggestionSet $completionResults
 558          * @return Title[]
 559          */
 560         public function extractTitles( SearchSuggestionSet $completionResults ) {
 561                 return $completionResults->map( function ( SearchSuggestion $sugg ) {
 562                         return $sugg->getSuggestedTitle();
 563                 } );
 564         }
 565
 566         /**
 567          * Process completion search results.
 568          * Resolves the titles and rescores.
 569          * @param string $search
 570          * @param SearchSuggestionSet $suggestions
 571          * @return SearchSuggestionSet
 572          */
 573         protected function processCompletionResults( $search, SearchSuggestionSet $suggestions ) {
 574                 $search = trim( $search );
 575                 // preload the titles with LinkBatch
 576                 $titles = $suggestions->map( function ( SearchSuggestion $sugg ) {
 577                         return $sugg->getSuggestedTitle();
 578                 } );
 579                 $lb = new LinkBatch( $titles );
 580                 $lb->setCaller( __METHOD__ );
 581                 $lb->execute();
 582
 583                 $results = $suggestions->map( function ( SearchSuggestion $sugg ) {
 584                         return $sugg->getSuggestedTitle()->getPrefixedText();
 585                 } );
 586
 587                 if ( $this->offset === 0 ) {
 588                         // Rescore results with an exact title match
 589                         // NOTE: in some cases like cross-namespace redirects
 590                         // (frequently used as shortcuts e.g. WP:WP on huwiki) some
 591                         // backends like Cirrus will return no results. We should still
 592                         // try an exact title match to workaround this limitation
 593                         $rescorer = new SearchExactMatchRescorer();
 594                         $rescoredResults = $rescorer->rescore( $search, $this->namespaces, $results, $this->limit );
 595                 } else {
 596                         // No need to rescore if offset is not 0
 597                         // The exact match must have been returned at position 0
 598                         // if it existed.
 599                         $rescoredResults = $results;
 600                 }
 601
 602                 if ( count( $rescoredResults ) > 0 ) {
 603                         $found = array_search( $rescoredResults[0], $results );
 604                         if ( $found === false ) {
 605                                 // If the first result is not in the previous array it
 606                                 // means that we found a new exact match
 607                                 $exactMatch = SearchSuggestion::fromTitle( 0, Title::newFromText( $rescoredResults[0] ) );
 608                                 $suggestions->prepend( $exactMatch );
 609                                 $suggestions->shrink( $this->limit );
 610                         } else {
 611                                 // if the first result is not the same we need to rescore
 612                                 if ( $found > 0 ) {
 613                                         $suggestions->rescore( $found );
 614                                 }
 615                         }
 616                 }
 617
 618                 return $suggestions;
 619         }
 620
 621         /**
 622          * Simple prefix search for subpages.
 623          * @param string $search
 624          * @return Title[]
 625          */
 626         public function defaultPrefixSearch( $search ) {
 627                 if ( trim( $search ) === '' ) {
 628                         return [];
 629                 }
 630
 631                 $search = $this->normalizeNamespaces( $search );
 632                 return $this->simplePrefixSearch( $search );
 633         }
 634
 635         /**
 636          * Call out to simple search backend.
 637          * Defaults to TitlePrefixSearch.
 638          * @param string $search
 639          * @return Title[]
 640          */
 641         protected function simplePrefixSearch( $search ) {
 642                 // Use default database prefix search
 643                 $backend = new TitlePrefixSearch;
 644                 return $backend->defaultSearchBackend( $this->namespaces, $search, $this->limit, $this->offset );
 645         }
 646
 647         /**
 648          * Make a list of searchable namespaces and their canonical names.
 649          * @deprecated since 1.27; use SearchEngineConfig::searchableNamespaces()
 650          * @return array
 651          */
 652         public static function searchableNamespaces() {
 653                 return MediaWikiServices::getInstance()->getSearchEngineConfig()->searchableNamespaces();
 654         }
 655
 656         /**
 657          * Extract default namespaces to search from the given user's
 658          * settings, returning a list of index numbers.
 659          * @deprecated since 1.27; use SearchEngineConfig::userNamespaces()
 660          * @param user $user
 661          * @return array
 662          */
 663         public static function userNamespaces( $user ) {
 664                 return MediaWikiServices::getInstance()->getSearchEngineConfig()->userNamespaces( $user );
 665         }
 666
 667         /**
 668          * An array of namespaces indexes to be searched by default
 669          * @deprecated since 1.27; use SearchEngineConfig::defaultNamespaces()
 670          * @return array
 671          */
 672         public static function defaultNamespaces() {
 673                 return MediaWikiServices::getInstance()->getSearchEngineConfig()->defaultNamespaces();
 674         }
 675
 676         /**
 677          * Get a list of namespace names useful for showing in tooltips
 678          * and preferences
 679          * @deprecated since 1.27; use SearchEngineConfig::namespacesAsText()
 680          * @param array $namespaces
 681          * @return array
 682          */
 683         public static function namespacesAsText( $namespaces ) {
 684                 return MediaWikiServices::getInstance()->getSearchEngineConfig()->namespacesAsText( $namespaces );
 685         }
 686
 687         /**
 688          * Load up the appropriate search engine class for the currently
 689          * active database backend, and return a configured instance.
 690          * @deprecated since 1.27; Use SearchEngineFactory::create
 691          * @param string $type Type of search backend, if not the default
 692          * @return SearchEngine
 693          */
 694         public static function create( $type = null ) {
 695                 return MediaWikiServices::getInstance()->getSearchEngineFactory()->create( $type );
 696         }
 697
 698         /**
 699          * Return the search engines we support. If only $wgSearchType
 700          * is set, it'll be an array of just that one item.
 701          * @deprecated since 1.27; use SearchEngineConfig::getSearchTypes()
 702          * @return array
 703          */
 704         public static function getSearchTypes() {
 705                 return MediaWikiServices::getInstance()->getSearchEngineConfig()->getSearchTypes();
 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 int $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, &$rowAugmentors ] );
 790
 791                 if ( !$setAugmentors && !$rowAugmentors ) {
 792                         // We're done here
 793                         return;
 794                 }
 795
 796                 // Convert row augmentors to set augmentor
 797                 foreach ( $rowAugmentors as $name => $row ) {
 798                         if ( isset( $setAugmentors[$name] ) ) {
 799                                 throw new InvalidArgumentException( "Both row and set augmentors are defined for $name" );
 800                         }
 801                         $setAugmentors[$name] = new PerRowAugmentor( $row );
 802                 }
 803
 804                 foreach ( $setAugmentors as $name => $augmentor ) {
 805                         $data = $augmentor->augmentAll( $resultSet );
 806                         if ( $data ) {
 807                                 $resultSet->setAugmentedData( $name, $data );
 808                         }
 809                 }
 810         }
 811 }
 812
 813 /**
 814  * Dummy class to be used when non-supported Database engine is present.
 815  * @todo FIXME: Dummy class should probably try something at least mildly useful,
 816  * such as a LIKE search through titles.
 817  * @ingroup Search
 818  */
 819 class SearchEngineDummy extends SearchEngine {
 820         // no-op
 821 }