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                 $allkeywords = [];
 339
 340                 $allkeywords[] = wfMessage( 'searchall' )->inContentLanguage()->text() . ":";
 341                 // force all: so that we have a common syntax for all the wikis
 342                 if ( !in_array( 'all:', $allkeywords ) ) {
 343                         $allkeywords[] = 'all:';
 344                 }
 345
 346                 $allQuery = false;
 347                 foreach ( $allkeywords as $kw ) {
 348                         if ( strncmp( $query, $kw, strlen( $kw ) ) == 0 ) {
 349                                 $extractedNamespace = null;
 350                                 $parsed = substr( $query, strlen( $kw ) );
 351                                 $allQuery = true;
 352                                 break;
 353                         }
 354                 }
 355
 356                 if ( !$allQuery && strpos( $query, ':' ) !== false ) {
 357                         // TODO: should we unify with PrefixSearch::extractNamespace ?
 358                         $prefix = str_replace( ' ', '_', substr( $query, 0, strpos( $query, ':' ) ) );
 359                         $index = $wgContLang->getNsIndex( $prefix );
 360                         if ( $index !== false ) {
 361                                 $extractedNamespace = [ $index ];
 362                                 $parsed = substr( $query, strlen( $prefix ) + 1 );
 363                         } else {
 364                                 return false;
 365                         }
 366                 }
 367
 368                 if ( trim( $parsed ) == '' ) {
 369                         $parsed = $query; // prefix was the whole query
 370                 }
 371
 372                 return [ $parsed, $extractedNamespace ];
 373         }
 374
 375         /**
 376          * Find snippet highlight settings for all users
 377          * @return array Contextlines, contextchars
 378          */
 379         public static function userHighlightPrefs() {
 380                 $contextlines = 2; // Hardcode this. Old defaults sucked. :)
 381                 $contextchars = 75; // same as above.... :P
 382                 return [ $contextlines, $contextchars ];
 383         }
 384
 385         /**
 386          * Create or update the search index record for the given page.
 387          * Title and text should be pre-processed.
 388          * STUB
 389          *
 390          * @param int $id
 391          * @param string $title
 392          * @param string $text
 393          */
 394         function update( $id, $title, $text ) {
 395                 // no-op
 396         }
 397
 398         /**
 399          * Update a search index record's title only.
 400          * Title should be pre-processed.
 401          * STUB
 402          *
 403          * @param int $id
 404          * @param string $title
 405          */
 406         function updateTitle( $id, $title ) {
 407                 // no-op
 408         }
 409
 410         /**
 411          * Delete an indexed page
 412          * Title should be pre-processed.
 413          * STUB
 414          *
 415          * @param int $id Page id that was deleted
 416          * @param string $title Title of page that was deleted
 417          */
 418         function delete( $id, $title ) {
 419                 // no-op
 420         }
 421
 422         /**
 423          * Get the raw text for updating the index from a content object
 424          * Nicer search backends could possibly do something cooler than
 425          * just returning raw text
 426          *
 427          * @todo This isn't ideal, we'd really like to have content-specific handling here
 428          * @param Title $t Title we're indexing
 429          * @param Content $c Content of the page to index
 430          * @return string
 431          */
 432         public function getTextFromContent( Title $t, Content $c = null ) {
 433                 return $c ? $c->getTextForSearchIndex() : '';
 434         }
 435
 436         /**
 437          * If an implementation of SearchEngine handles all of its own text processing
 438          * in getTextFromContent() and doesn't require SearchUpdate::updateText()'s
 439          * rather silly handling, it should return true here instead.
 440          *
 441          * @return bool
 442          */
 443         public function textAlreadyUpdatedForIndex() {
 444                 return false;
 445         }
 446
 447         /**
 448          * Makes search simple string if it was namespaced.
 449          * Sets namespaces of the search to namespaces extracted from string.
 450          * @param string $search
 451          * @return string Simplified search string
 452          */
 453         protected function normalizeNamespaces( $search ) {
 454                 // Find a Title which is not an interwiki and is in NS_MAIN
 455                 $title = Title::newFromText( $search );
 456                 $ns = $this->namespaces;
 457                 if ( $title && !$title->isExternal() ) {
 458                         $ns = [ $title->getNamespace() ];
 459                         $search = $title->getText();
 460                         if ( $ns[0] == NS_MAIN ) {
 461                                 $ns = $this->namespaces; // no explicit prefix, use default namespaces
 462                                 Hooks::run( 'PrefixSearchExtractNamespace', [ &$ns, &$search ] );
 463                         }
 464                 } else {
 465                         $title = Title::newFromText( $search . 'Dummy' );
 466                         if ( $title && $title->getText() == 'Dummy'
 467                                         && $title->getNamespace() != NS_MAIN
 468                                         && !$title->isExternal()
 469                         ) {
 470                                 $ns = [ $title->getNamespace() ];
 471                                 $search = '';
 472                         } else {
 473                                 Hooks::run( 'PrefixSearchExtractNamespace', [ &$ns, &$search ] );
 474                         }
 475                 }
 476
 477                 $ns = array_map( function ( $space ) {
 478                         return $space == NS_MEDIA ? NS_FILE : $space;
 479                 }, $ns );
 480
 481                 $this->setNamespaces( $ns );
 482                 return $search;
 483         }
 484
 485         /**
 486          * Perform a completion search.
 487          * Does not resolve namespaces and does not check variants.
 488          * Search engine implementations may want to override this function.
 489          * @param string $search
 490          * @return SearchSuggestionSet
 491          */
 492         protected function completionSearchBackend( $search ) {
 493                 $results = [];
 494
 495                 $search = trim( $search );
 496
 497                 if ( !in_array( NS_SPECIAL, $this->namespaces ) && // We do not run hook on Special: search
 498                          !Hooks::run( 'PrefixSearchBackend',
 499                                 [ $this->namespaces, $search, $this->limit, &$results, $this->offset ]
 500                 ) ) {
 501                         // False means hook worked.
 502                         // FIXME: Yes, the API is weird. That's why it is going to be deprecated.
 503
 504                         return SearchSuggestionSet::fromStrings( $results );
 505                 } else {
 506                         // Hook did not do the job, use default simple search
 507                         $results = $this->simplePrefixSearch( $search );
 508                         return SearchSuggestionSet::fromTitles( $results );
 509                 }
 510         }
 511
 512         /**
 513          * Perform a completion search.
 514          * @param string $search
 515          * @return SearchSuggestionSet
 516          */
 517         public function completionSearch( $search ) {
 518                 if ( trim( $search ) === '' ) {
 519                         return SearchSuggestionSet::emptySuggestionSet(); // Return empty result
 520                 }
 521                 $search = $this->normalizeNamespaces( $search );
 522                 return $this->processCompletionResults( $search, $this->completionSearchBackend( $search ) );
 523         }
 524
 525         /**
 526          * Perform a completion search with variants.
 527          * @param string $search
 528          * @return SearchSuggestionSet
 529          */
 530         public function completionSearchWithVariants( $search ) {
 531                 if ( trim( $search ) === '' ) {
 532                         return SearchSuggestionSet::emptySuggestionSet(); // Return empty result
 533                 }
 534                 $search = $this->normalizeNamespaces( $search );
 535
 536                 $results = $this->completionSearchBackend( $search );
 537                 $fallbackLimit = $this->limit - $results->getSize();
 538                 if ( $fallbackLimit > 0 ) {
 539                         global $wgContLang;
 540
 541                         $fallbackSearches = $wgContLang->autoConvertToAllVariants( $search );
 542                         $fallbackSearches = array_diff( array_unique( $fallbackSearches ), [ $search ] );
 543
 544                         foreach ( $fallbackSearches as $fbs ) {
 545                                 $this->setLimitOffset( $fallbackLimit );
 546                                 $fallbackSearchResult = $this->completionSearch( $fbs );
 547                                 $results->appendAll( $fallbackSearchResult );
 548                                 $fallbackLimit -= $fallbackSearchResult->getSize();
 549                                 if ( $fallbackLimit <= 0 ) {
 550                                         break;
 551                                 }
 552                         }
 553                 }
 554                 return $this->processCompletionResults( $search, $results );
 555         }
 556
 557         /**
 558          * Extract titles from completion results
 559          * @param SearchSuggestionSet $completionResults
 560          * @return Title[]
 561          */
 562         public function extractTitles( SearchSuggestionSet $completionResults ) {
 563                 return $completionResults->map( function ( SearchSuggestion $sugg ) {
 564                         return $sugg->getSuggestedTitle();
 565                 } );
 566         }
 567
 568         /**
 569          * Process completion search results.
 570          * Resolves the titles and rescores.
 571          * @param string $search
 572          * @param SearchSuggestionSet $suggestions
 573          * @return SearchSuggestionSet
 574          */
 575         protected function processCompletionResults( $search, SearchSuggestionSet $suggestions ) {
 576                 $search = trim( $search );
 577                 // preload the titles with LinkBatch
 578                 $titles = $suggestions->map( function ( SearchSuggestion $sugg ) {
 579                         return $sugg->getSuggestedTitle();
 580                 } );
 581                 $lb = new LinkBatch( $titles );
 582                 $lb->setCaller( __METHOD__ );
 583                 $lb->execute();
 584
 585                 $results = $suggestions->map( function ( SearchSuggestion $sugg ) {
 586                         return $sugg->getSuggestedTitle()->getPrefixedText();
 587                 } );
 588
 589                 if ( $this->offset === 0 ) {
 590                         // Rescore results with an exact title match
 591                         // NOTE: in some cases like cross-namespace redirects
 592                         // (frequently used as shortcuts e.g. WP:WP on huwiki) some
 593                         // backends like Cirrus will return no results. We should still
 594                         // try an exact title match to workaround this limitation
 595                         $rescorer = new SearchExactMatchRescorer();
 596                         $rescoredResults = $rescorer->rescore( $search, $this->namespaces, $results, $this->limit );
 597                 } else {
 598                         // No need to rescore if offset is not 0
 599                         // The exact match must have been returned at position 0
 600                         // if it existed.
 601                         $rescoredResults = $results;
 602                 }
 603
 604                 if ( count( $rescoredResults ) > 0 ) {
 605                         $found = array_search( $rescoredResults[0], $results );
 606                         if ( $found === false ) {
 607                                 // If the first result is not in the previous array it
 608                                 // means that we found a new exact match
 609                                 $exactMatch = SearchSuggestion::fromTitle( 0, Title::newFromText( $rescoredResults[0] ) );
 610                                 $suggestions->prepend( $exactMatch );
 611                                 $suggestions->shrink( $this->limit );
 612                         } else {
 613                                 // if the first result is not the same we need to rescore
 614                                 if ( $found > 0 ) {
 615                                         $suggestions->rescore( $found );
 616                                 }
 617                         }
 618                 }
 619
 620                 return $suggestions;
 621         }
 622
 623         /**
 624          * Simple prefix search for subpages.
 625          * @param string $search
 626          * @return Title[]
 627          */
 628         public function defaultPrefixSearch( $search ) {
 629                 if ( trim( $search ) === '' ) {
 630                         return [];
 631                 }
 632
 633                 $search = $this->normalizeNamespaces( $search );
 634                 return $this->simplePrefixSearch( $search );
 635         }
 636
 637         /**
 638          * Call out to simple search backend.
 639          * Defaults to TitlePrefixSearch.
 640          * @param string $search
 641          * @return Title[]
 642          */
 643         protected function simplePrefixSearch( $search ) {
 644                 // Use default database prefix search
 645                 $backend = new TitlePrefixSearch;
 646                 return $backend->defaultSearchBackend( $this->namespaces, $search, $this->limit, $this->offset );
 647         }
 648
 649         /**
 650          * Make a list of searchable namespaces and their canonical names.
 651          * @deprecated since 1.27; use SearchEngineConfig::searchableNamespaces()
 652          * @return array
 653          */
 654         public static function searchableNamespaces() {
 655                 return MediaWikiServices::getInstance()->getSearchEngineConfig()->searchableNamespaces();
 656         }
 657
 658         /**
 659          * Extract default namespaces to search from the given user's
 660          * settings, returning a list of index numbers.
 661          * @deprecated since 1.27; use SearchEngineConfig::userNamespaces()
 662          * @param user $user
 663          * @return array
 664          */
 665         public static function userNamespaces( $user ) {
 666                 return MediaWikiServices::getInstance()->getSearchEngineConfig()->userNamespaces( $user );
 667         }
 668
 669         /**
 670          * An array of namespaces indexes to be searched by default
 671          * @deprecated since 1.27; use SearchEngineConfig::defaultNamespaces()
 672          * @return array
 673          */
 674         public static function defaultNamespaces() {
 675                 return MediaWikiServices::getInstance()->getSearchEngineConfig()->defaultNamespaces();
 676         }
 677
 678         /**
 679          * Get a list of namespace names useful for showing in tooltips
 680          * and preferences
 681          * @deprecated since 1.27; use SearchEngineConfig::namespacesAsText()
 682          * @param array $namespaces
 683          * @return array
 684          */
 685         public static function namespacesAsText( $namespaces ) {
 686                 return MediaWikiServices::getInstance()->getSearchEngineConfig()->namespacesAsText( $namespaces );
 687         }
 688
 689         /**
 690          * Load up the appropriate search engine class for the currently
 691          * active database backend, and return a configured instance.
 692          * @deprecated since 1.27; Use SearchEngineFactory::create
 693          * @param string $type Type of search backend, if not the default
 694          * @return SearchEngine
 695          */
 696         public static function create( $type = null ) {
 697                 return MediaWikiServices::getInstance()->getSearchEngineFactory()->create( $type );
 698         }
 699
 700         /**
 701          * Return the search engines we support. If only $wgSearchType
 702          * is set, it'll be an array of just that one item.
 703          * @deprecated since 1.27; use SearchEngineConfig::getSearchTypes()
 704          * @return array
 705          */
 706         public static function getSearchTypes() {
 707                 return MediaWikiServices::getInstance()->getSearchEngineConfig()->getSearchTypes();
 708         }
 709
 710         /**
 711          * Get a list of supported profiles.
 712          * Some search engine implementations may expose specific profiles to fine-tune
 713          * its behaviors.
 714          * The profile can be passed as a feature data with setFeatureData( $profileType, $profileName )
 715          * The array returned by this function contains the following keys:
 716          * - name: the profile name to use with setFeatureData
 717          * - desc-message: the i18n description
 718          * - default: set to true if this profile is the default
 719          *
 720          * @since 1.28
 721          * @param string $profileType the type of profiles
 722          * @param User|null $user the user requesting the list of profiles
 723          * @return array|null the list of profiles or null if none available
 724          */
 725         public function getProfiles( $profileType, User $user = null ) {
 726                 return null;
 727         }
 728
 729         /**
 730          * Create a search field definition.
 731          * Specific search engines should override this method to create search fields.
 732          * @param string $name
 733          * @param int $type One of the types in SearchIndexField::INDEX_TYPE_*
 734          * @return SearchIndexField
 735          * @since 1.28
 736          */
 737         public function makeSearchFieldMapping( $name, $type ) {
 738                 return new NullIndexField();
 739         }
 740
 741         /**
 742          * Get fields for search index
 743          * @since 1.28
 744          * @return SearchIndexField[] Index field definitions for all content handlers
 745          */
 746         public function getSearchIndexFields() {
 747                 $models = ContentHandler::getContentModels();
 748                 $fields = [];
 749                 $seenHandlers = new SplObjectStorage();
 750                 foreach ( $models as $model ) {
 751                         try {
 752                                 $handler = ContentHandler::getForModelID( $model );
 753                         }
 754                         catch ( MWUnknownContentModelException $e ) {
 755                                 // If we can find no handler, ignore it
 756                                 continue;
 757                         }
 758                         // Several models can have the same handler, so avoid processing it repeatedly
 759                         if ( $seenHandlers->contains( $handler ) ) {
 760                                 // We already did this one
 761                                 continue;
 762                         }
 763                         $seenHandlers->attach( $handler );
 764                         $handlerFields = $handler->getFieldsForSearchIndex( $this );
 765                         foreach ( $handlerFields as $fieldName => $fieldData ) {
 766                                 if ( empty( $fields[$fieldName] ) ) {
 767                                         $fields[$fieldName] = $fieldData;
 768                                 } else {
 769                                         // TODO: do we allow some clashes with the same type or reject all of them?
 770                                         $mergeDef = $fields[$fieldName]->merge( $fieldData );
 771                                         if ( !$mergeDef ) {
 772                                                 throw new InvalidArgumentException( "Duplicate field $fieldName for model $model" );
 773                                         }
 774                                         $fields[$fieldName] = $mergeDef;
 775                                 }
 776                         }
 777                 }
 778                 // Hook to allow extensions to produce search mapping fields
 779                 Hooks::run( 'SearchIndexFields', [ &$fields, $this ] );
 780                 return $fields;
 781         }
 782
 783         /**
 784          * Augment search results with extra data.
 785          *
 786          * @param SearchResultSet $resultSet
 787          */
 788         public function augmentSearchResults( SearchResultSet $resultSet ) {
 789                 $setAugmentors = [];
 790                 $rowAugmentors = [];
 791                 Hooks::run( "SearchResultsAugment", [ &$setAugmentors, &$rowAugmentors ] );
 792
 793                 if ( !$setAugmentors && !$rowAugmentors ) {
 794                         // We're done here
 795                         return;
 796                 }
 797
 798                 // Convert row augmentors to set augmentor
 799                 foreach ( $rowAugmentors as $name => $row ) {
 800                         if ( isset( $setAugmentors[$name] ) ) {
 801                                 throw new InvalidArgumentException( "Both row and set augmentors are defined for $name" );
 802                         }
 803                         $setAugmentors[$name] = new PerRowAugmentor( $row );
 804                 }
 805
 806                 foreach ( $setAugmentors as $name => $augmentor ) {
 807                         $data = $augmentor->augmentAll( $resultSet );
 808                         if ( $data ) {
 809                                 $resultSet->setAugmentedData( $name, $data );
 810                         }
 811                 }
 812         }
 813 }
 814
 815 /**
 816  * Dummy class to be used when non-supported Database engine is present.
 817  * @todo FIXME: Dummy class should probably try something at least mildly useful,
 818  * such as a LIKE search through titles.
 819  * @ingroup Search
 820  */
 821 class SearchEngineDummy extends SearchEngine {
 822         // no-op
 823 }