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         /**
  64          * Perform a full text search query and return a result set.
  65          * If full text searches are not supported or disabled, return null.
  66          * STUB
  67          *
  68          * @param string $term Raw search term
  69          * @return SearchResultSet|Status|null
  70          */
  71         function searchText( $term ) {
  72                 return null;
  73         }
  74
  75         /**
  76          * Perform a title-only search query and return a result set.
  77          * If title searches are not supported or disabled, return null.
  78          * STUB
  79          *
  80          * @param string $term Raw search term
  81          * @return SearchResultSet|null
  82          */
  83         function searchTitle( $term ) {
  84                 return null;
  85         }
  86
  87         /**
  88          * @since 1.18
  89          * @param string $feature
  90          * @return bool
  91          */
  92         public function supports( $feature ) {
  93                 switch ( $feature ) {
  94                 case 'search-update':
  95                         return true;
  96                 case 'title-suffix-filter':
  97                 default:
  98                         return false;
  99                 }
 100         }
 101
 102         /**
 103          * Way to pass custom data for engines
 104          * @since 1.18
 105          * @param string $feature
 106          * @param mixed $data
 107          */
 108         public function setFeatureData( $feature, $data ) {
 109                 $this->features[$feature] = $data;
 110         }
 111
 112         /**
 113          * Way to retrieve custom data set by setFeatureData
 114          * or by the engine itself.
 115          * @since 1.29
 116          * @param string $feature feature name
 117          * @return mixed the feature value or null if unset
 118          */
 119         public function getFeatureData( $feature ) {
 120                 if ( isset ( $this->features[$feature] ) ) {
 121                         return $this->features[$feature];
 122                 }
 123                 return null;
 124         }
 125
 126         /**
 127          * When overridden in derived class, performs database-specific conversions
 128          * on text to be used for searching or updating search index.
 129          * Default implementation does nothing (simply returns $string).
 130          *
 131          * @param string $string String to process
 132          * @return string
 133          */
 134         public function normalizeText( $string ) {
 135                 global $wgContLang;
 136
 137                 // Some languages such as Chinese require word segmentation
 138                 return $wgContLang->segmentByWord( $string );
 139         }
 140
 141         /**
 142          * Transform search term in cases when parts of the query came as different
 143          * GET params (when supported), e.g. for prefix queries:
 144          * search=test&prefix=Main_Page/Archive -> test prefix:Main Page/Archive
 145          * @param string $term
 146          * @return string
 147          */
 148         public function transformSearchTerm( $term ) {
 149                 return $term;
 150         }
 151
 152         /**
 153          * Get service class to finding near matches.
 154          * @param Config $config Configuration to use for the matcher.
 155          * @return SearchNearMatcher
 156          */
 157         public function getNearMatcher( Config $config ) {
 158                 global $wgContLang;
 159                 return new SearchNearMatcher( $config, $wgContLang );
 160         }
 161
 162         /**
 163          * Get near matcher for default SearchEngine.
 164          * @return SearchNearMatcher
 165          */
 166         protected static function defaultNearMatcher() {
 167                 $config = MediaWikiServices::getInstance()->getMainConfig();
 168                 return MediaWikiServices::getInstance()->newSearchEngine()->getNearMatcher( $config );
 169         }
 170
 171         /**
 172          * If an exact title match can be found, or a very slightly close match,
 173          * return the title. If no match, returns NULL.
 174          * @deprecated since 1.27; Use SearchEngine::getNearMatcher()
 175          * @param string $searchterm
 176          * @return Title
 177          */
 178         public static function getNearMatch( $searchterm ) {
 179                 return static::defaultNearMatcher()->getNearMatch( $searchterm );
 180         }
 181
 182         /**
 183          * Do a near match (see SearchEngine::getNearMatch) and wrap it into a
 184          * SearchResultSet.
 185          * @deprecated since 1.27; Use SearchEngine::getNearMatcher()
 186          * @param string $searchterm
 187          * @return SearchResultSet
 188          */
 189         public static function getNearMatchResultSet( $searchterm ) {
 190                 return static::defaultNearMatcher()->getNearMatchResultSet( $searchterm );
 191         }
 192
 193         /**
 194          * Get chars legal for search.
 195          * NOTE: usage as static is deprecated and preserved only as BC measure
 196          * @return string
 197          */
 198         public static function legalSearchChars() {
 199                 return "A-Za-z_'.0-9\\x80-\\xFF\\-";
 200         }
 201
 202         /**
 203          * Set the maximum number of results to return
 204          * and how many to skip before returning the first.
 205          *
 206          * @param int $limit
 207          * @param int $offset
 208          */
 209         function setLimitOffset( $limit, $offset = 0 ) {
 210                 $this->limit = intval( $limit );
 211                 $this->offset = intval( $offset );
 212         }
 213
 214         /**
 215          * Set which namespaces the search should include.
 216          * Give an array of namespace index numbers.
 217          *
 218          * @param int[]|null $namespaces
 219          */
 220         function setNamespaces( $namespaces ) {
 221                 if ( $namespaces ) {
 222                         // Filter namespaces to only keep valid ones
 223                         $validNs = $this->searchableNamespaces();
 224                         $namespaces = array_filter( $namespaces, function( $ns ) use( $validNs ) {
 225                                 return $ns < 0 || isset( $validNs[$ns] );
 226                         } );
 227                 } else {
 228                         $namespaces = [];
 229                 }
 230                 $this->namespaces = $namespaces;
 231         }
 232
 233         /**
 234          * Set whether the searcher should try to build a suggestion.  Note: some searchers
 235          * don't support building a suggestion in the first place and others don't respect
 236          * this flag.
 237          *
 238          * @param bool $showSuggestion Should the searcher try to build suggestions
 239          */
 240         function setShowSuggestion( $showSuggestion ) {
 241                 $this->showSuggestion = $showSuggestion;
 242         }
 243
 244         /**
 245          * Get the valid sort directions.  All search engines support 'relevance' but others
 246          * might support more. The default in all implementations should be 'relevance.'
 247          *
 248          * @since 1.25
 249          * @return array(string) the valid sort directions for setSort
 250          */
 251         public function getValidSorts() {
 252                 return [ 'relevance' ];
 253         }
 254
 255         /**
 256          * Set the sort direction of the search results. Must be one returned by
 257          * SearchEngine::getValidSorts()
 258          *
 259          * @since 1.25
 260          * @throws InvalidArgumentException
 261          * @param string $sort sort direction for query result
 262          */
 263         public function setSort( $sort ) {
 264                 if ( !in_array( $sort, $this->getValidSorts() ) ) {
 265                         throw new InvalidArgumentException( "Invalid sort: $sort. " .
 266                                 "Must be one of: " . implode( ', ', $this->getValidSorts() ) );
 267                 }
 268                 $this->sort = $sort;
 269         }
 270
 271         /**
 272          * Get the sort direction of the search results
 273          *
 274          * @since 1.25
 275          * @return string
 276          */
 277         public function getSort() {
 278                 return $this->sort;
 279         }
 280
 281         /**
 282          * Parse some common prefixes: all (search everything)
 283          * or namespace names and set the list of namespaces
 284          * of this class accordingly.
 285          *
 286          * @param string $query
 287          * @return string
 288          */
 289         function replacePrefixes( $query ) {
 290                 $queryAndNs = self::parseNamespacePrefixes( $query );
 291                 if ( $queryAndNs === false ) {
 292                         return $query;
 293                 }
 294                 $this->namespaces = $queryAndNs[1];
 295                 return $queryAndNs[0];
 296         }
 297
 298         /**
 299          * Parse some common prefixes: all (search everything)
 300          * or namespace names
 301          *
 302          * @param string $query
 303          * @return false|array false if no namespace was extracted, an array
 304          * with the parsed query at index 0 and an array of namespaces at index
 305          * 1 (or null for all namespaces).
 306          */
 307         public static function parseNamespacePrefixes( $query ) {
 308                 global $wgContLang;
 309
 310                 $parsed = $query;
 311                 if ( strpos( $query, ':' ) === false ) { // nothing to do
 312                         return false;
 313                 }
 314                 $extractedNamespace = null;
 315
 316                 $allkeyword = wfMessage( 'searchall' )->inContentLanguage()->text() . ":";
 317                 if ( strncmp( $query, $allkeyword, strlen( $allkeyword ) ) == 0 ) {
 318                         $extractedNamespace = null;
 319                         $parsed = substr( $query, strlen( $allkeyword ) );
 320                 } elseif ( strpos( $query, ':' ) !== false ) {
 321                         // TODO: should we unify with PrefixSearch::extractNamespace ?
 322                         $prefix = str_replace( ' ', '_', substr( $query, 0, strpos( $query, ':' ) ) );
 323                         $index = $wgContLang->getNsIndex( $prefix );
 324                         if ( $index !== false ) {
 325                                 $extractedNamespace = [ $index ];
 326                                 $parsed = substr( $query, strlen( $prefix ) + 1 );
 327                         } else {
 328                                 return false;
 329                         }
 330                 }
 331
 332                 if ( trim( $parsed ) == '' ) {
 333                         $parsed = $query; // prefix was the whole query
 334                 }
 335
 336                 return [ $parsed, $extractedNamespace ];
 337         }
 338
 339         /**
 340          * Find snippet highlight settings for all users
 341          * @return array Contextlines, contextchars
 342          */
 343         public static function userHighlightPrefs() {
 344                 $contextlines = 2; // Hardcode this. Old defaults sucked. :)
 345                 $contextchars = 75; // same as above.... :P
 346                 return [ $contextlines, $contextchars ];
 347         }
 348
 349         /**
 350          * Create or update the search index record for the given page.
 351          * Title and text should be pre-processed.
 352          * STUB
 353          *
 354          * @param int $id
 355          * @param string $title
 356          * @param string $text
 357          */
 358         function update( $id, $title, $text ) {
 359                 // no-op
 360         }
 361
 362         /**
 363          * Update a search index record's title only.
 364          * Title should be pre-processed.
 365          * STUB
 366          *
 367          * @param int $id
 368          * @param string $title
 369          */
 370         function updateTitle( $id, $title ) {
 371                 // no-op
 372         }
 373
 374         /**
 375          * Delete an indexed page
 376          * Title should be pre-processed.
 377          * STUB
 378          *
 379          * @param int $id Page id that was deleted
 380          * @param string $title Title of page that was deleted
 381          */
 382         function delete( $id, $title ) {
 383                 // no-op
 384         }
 385
 386         /**
 387          * Get OpenSearch suggestion template
 388          *
 389          * @deprecated since 1.25
 390          * @return string
 391          */
 392         public static function getOpenSearchTemplate() {
 393                 wfDeprecated( __METHOD__, '1.25' );
 394                 return ApiOpenSearch::getOpenSearchTemplate( 'application/x-suggestions+json' );
 395         }
 396
 397         /**
 398          * Get the raw text for updating the index from a content object
 399          * Nicer search backends could possibly do something cooler than
 400          * just returning raw text
 401          *
 402          * @todo This isn't ideal, we'd really like to have content-specific handling here
 403          * @param Title $t Title we're indexing
 404          * @param Content $c Content of the page to index
 405          * @return string
 406          */
 407         public function getTextFromContent( Title $t, Content $c = null ) {
 408                 return $c ? $c->getTextForSearchIndex() : '';
 409         }
 410
 411         /**
 412          * If an implementation of SearchEngine handles all of its own text processing
 413          * in getTextFromContent() and doesn't require SearchUpdate::updateText()'s
 414          * rather silly handling, it should return true here instead.
 415          *
 416          * @return bool
 417          */
 418         public function textAlreadyUpdatedForIndex() {
 419                 return false;
 420         }
 421
 422         /**
 423          * Makes search simple string if it was namespaced.
 424          * Sets namespaces of the search to namespaces extracted from string.
 425          * @param string $search
 426          * @return string Simplified search string
 427          */
 428         protected function normalizeNamespaces( $search ) {
 429                 // Find a Title which is not an interwiki and is in NS_MAIN
 430                 $title = Title::newFromText( $search );
 431                 $ns = $this->namespaces;
 432                 if ( $title && !$title->isExternal() ) {
 433                         $ns = [ $title->getNamespace() ];
 434                         $search = $title->getText();
 435                         if ( $ns[0] == NS_MAIN ) {
 436                                 $ns = $this->namespaces; // no explicit prefix, use default namespaces
 437                                 Hooks::run( 'PrefixSearchExtractNamespace', [ &$ns, &$search ] );
 438                         }
 439                 } else {
 440                         $title = Title::newFromText( $search . 'Dummy' );
 441                         if ( $title && $title->getText() == 'Dummy'
 442                                         && $title->getNamespace() != NS_MAIN
 443                                         && !$title->isExternal() )
 444                         {
 445                                 $ns = [ $title->getNamespace() ];
 446                                 $search = '';
 447                         } else {
 448                                 Hooks::run( 'PrefixSearchExtractNamespace', [ &$ns, &$search ] );
 449                         }
 450                 }
 451
 452                 $ns = array_map( function( $space ) {
 453                         return $space == NS_MEDIA ? NS_FILE : $space;
 454                 }, $ns );
 455
 456                 $this->setNamespaces( $ns );
 457                 return $search;
 458         }
 459
 460         /**
 461          * Perform a completion search.
 462          * Does not resolve namespaces and does not check variants.
 463          * Search engine implementations may want to override this function.
 464          * @param string $search
 465          * @return SearchSuggestionSet
 466          */
 467         protected function completionSearchBackend( $search ) {
 468                 $results = [];
 469
 470                 $search = trim( $search );
 471
 472                 if ( !in_array( NS_SPECIAL, $this->namespaces ) && // We do not run hook on Special: search
 473                          !Hooks::run( 'PrefixSearchBackend',
 474                                 [ $this->namespaces, $search, $this->limit, &$results, $this->offset ]
 475                 ) ) {
 476                         // False means hook worked.
 477                         // FIXME: Yes, the API is weird. That's why it is going to be deprecated.
 478
 479                         return SearchSuggestionSet::fromStrings( $results );
 480                 } else {
 481                         // Hook did not do the job, use default simple search
 482                         $results = $this->simplePrefixSearch( $search );
 483                         return SearchSuggestionSet::fromTitles( $results );
 484                 }
 485         }
 486
 487         /**
 488          * Perform a completion search.
 489          * @param string $search
 490          * @return SearchSuggestionSet
 491          */
 492         public function completionSearch( $search ) {
 493                 if ( trim( $search ) === '' ) {
 494                         return SearchSuggestionSet::emptySuggestionSet(); // Return empty result
 495                 }
 496                 $search = $this->normalizeNamespaces( $search );
 497                 return $this->processCompletionResults( $search, $this->completionSearchBackend( $search ) );
 498         }
 499
 500         /**
 501          * Perform a completion search with variants.
 502          * @param string $search
 503          * @return SearchSuggestionSet
 504          */
 505         public function completionSearchWithVariants( $search ) {
 506                 if ( trim( $search ) === '' ) {
 507                         return SearchSuggestionSet::emptySuggestionSet(); // Return empty result
 508                 }
 509                 $search = $this->normalizeNamespaces( $search );
 510
 511                 $results = $this->completionSearchBackend( $search );
 512                 $fallbackLimit = $this->limit - $results->getSize();
 513                 if ( $fallbackLimit > 0 ) {
 514                         global $wgContLang;
 515
 516                         $fallbackSearches = $wgContLang->autoConvertToAllVariants( $search );
 517                         $fallbackSearches = array_diff( array_unique( $fallbackSearches ), [ $search ] );
 518
 519                         foreach ( $fallbackSearches as $fbs ) {
 520                                 $this->setLimitOffset( $fallbackLimit );
 521                                 $fallbackSearchResult = $this->completionSearch( $fbs );
 522                                 $results->appendAll( $fallbackSearchResult );
 523                                 $fallbackLimit -= count( $fallbackSearchResult );
 524                                 if ( $fallbackLimit <= 0 ) {
 525                                         break;
 526                                 }
 527                         }
 528                 }
 529                 return $this->processCompletionResults( $search, $results );
 530         }
 531
 532         /**
 533          * Extract titles from completion results
 534          * @param SearchSuggestionSet $completionResults
 535          * @return Title[]
 536          */
 537         public function extractTitles( SearchSuggestionSet $completionResults ) {
 538                 return $completionResults->map( function( SearchSuggestion $sugg ) {
 539                         return $sugg->getSuggestedTitle();
 540                 } );
 541         }
 542
 543         /**
 544          * Process completion search results.
 545          * Resolves the titles and rescores.
 546          * @param SearchSuggestionSet $suggestions
 547          * @return SearchSuggestionSet
 548          */
 549         protected function processCompletionResults( $search, SearchSuggestionSet $suggestions ) {
 550                 $search = trim( $search );
 551                 // preload the titles with LinkBatch
 552                 $titles = $suggestions->map( function( SearchSuggestion $sugg ) {
 553                         return $sugg->getSuggestedTitle();
 554                 } );
 555                 $lb = new LinkBatch( $titles );
 556                 $lb->setCaller( __METHOD__ );
 557                 $lb->execute();
 558
 559                 $results = $suggestions->map( function( SearchSuggestion $sugg ) {
 560                         return $sugg->getSuggestedTitle()->getPrefixedText();
 561                 } );
 562
 563                 if ( $this->offset === 0 ) {
 564                         // Rescore results with an exact title match
 565                         // NOTE: in some cases like cross-namespace redirects
 566                         // (frequently used as shortcuts e.g. WP:WP on huwiki) some
 567                         // backends like Cirrus will return no results. We should still
 568                         // try an exact title match to workaround this limitation
 569                         $rescorer = new SearchExactMatchRescorer();
 570                         $rescoredResults = $rescorer->rescore( $search, $this->namespaces, $results, $this->limit );
 571                 } else {
 572                         // No need to rescore if offset is not 0
 573                         // The exact match must have been returned at position 0
 574                         // if it existed.
 575                         $rescoredResults = $results;
 576                 }
 577
 578                 if ( count( $rescoredResults ) > 0 ) {
 579                         $found = array_search( $rescoredResults[0], $results );
 580                         if ( $found === false ) {
 581                                 // If the first result is not in the previous array it
 582                                 // means that we found a new exact match
 583                                 $exactMatch = SearchSuggestion::fromTitle( 0, Title::newFromText( $rescoredResults[0] ) );
 584                                 $suggestions->prepend( $exactMatch );
 585                                 $suggestions->shrink( $this->limit );
 586                         } else {
 587                                 // if the first result is not the same we need to rescore
 588                                 if ( $found > 0 ) {
 589                                         $suggestions->rescore( $found );
 590                                 }
 591                         }
 592                 }
 593
 594                 return $suggestions;
 595         }
 596
 597         /**
 598          * Simple prefix search for subpages.
 599          * @param string $search
 600          * @return Title[]
 601          */
 602         public function defaultPrefixSearch( $search ) {
 603                 if ( trim( $search ) === '' ) {
 604                         return [];
 605                 }
 606
 607                 $search = $this->normalizeNamespaces( $search );
 608                 return $this->simplePrefixSearch( $search );
 609         }
 610
 611         /**
 612          * Call out to simple search backend.
 613          * Defaults to TitlePrefixSearch.
 614          * @param string $search
 615          * @return Title[]
 616          */
 617         protected function simplePrefixSearch( $search ) {
 618                 // Use default database prefix search
 619                 $backend = new TitlePrefixSearch;
 620                 return $backend->defaultSearchBackend( $this->namespaces, $search, $this->limit, $this->offset );
 621         }
 622
 623         /**
 624          * Make a list of searchable namespaces and their canonical names.
 625          * @deprecated since 1.27; use SearchEngineConfig::searchableNamespaces()
 626          * @return array
 627          */
 628         public static function searchableNamespaces() {
 629                 return MediaWikiServices::getInstance()->getSearchEngineConfig()->searchableNamespaces();
 630         }
 631
 632         /**
 633          * Extract default namespaces to search from the given user's
 634          * settings, returning a list of index numbers.
 635          * @deprecated since 1.27; use SearchEngineConfig::userNamespaces()
 636          * @param user $user
 637          * @return array
 638          */
 639         public static function userNamespaces( $user ) {
 640                 return MediaWikiServices::getInstance()->getSearchEngineConfig()->userNamespaces( $user );
 641         }
 642
 643         /**
 644          * An array of namespaces indexes to be searched by default
 645          * @deprecated since 1.27; use SearchEngineConfig::defaultNamespaces()
 646          * @return array
 647          */
 648         public static function defaultNamespaces() {
 649                 return MediaWikiServices::getInstance()->getSearchEngineConfig()->defaultNamespaces();
 650         }
 651
 652         /**
 653          * Get a list of namespace names useful for showing in tooltips
 654          * and preferences
 655          * @deprecated since 1.27; use SearchEngineConfig::namespacesAsText()
 656          * @param array $namespaces
 657          * @return array
 658          */
 659         public static function namespacesAsText( $namespaces ) {
 660                 return MediaWikiServices::getInstance()->getSearchEngineConfig()->namespacesAsText( $namespaces );
 661         }
 662
 663         /**
 664          * Load up the appropriate search engine class for the currently
 665          * active database backend, and return a configured instance.
 666          * @deprecated since 1.27; Use SearchEngineFactory::create
 667          * @param string $type Type of search backend, if not the default
 668          * @return SearchEngine
 669          */
 670         public static function create( $type = null ) {
 671                 return MediaWikiServices::getInstance()->getSearchEngineFactory()->create( $type );
 672         }
 673
 674         /**
 675          * Return the search engines we support. If only $wgSearchType
 676          * is set, it'll be an array of just that one item.
 677          * @deprecated since 1.27; use SearchEngineConfig::getSearchTypes()
 678          * @return array
 679          */
 680         public static function getSearchTypes() {
 681                 return MediaWikiServices::getInstance()->getSearchEngineConfig()->getSearchTypes();
 682         }
 683
 684         /**
 685          * Get a list of supported profiles.
 686          * Some search engine implementations may expose specific profiles to fine-tune
 687          * its behaviors.
 688          * The profile can be passed as a feature data with setFeatureData( $profileType, $profileName )
 689          * The array returned by this function contains the following keys:
 690          * - name: the profile name to use with setFeatureData
 691          * - desc-message: the i18n description
 692          * - default: set to true if this profile is the default
 693          *
 694          * @since 1.28
 695          * @param string $profileType the type of profiles
 696          * @param User|null $user the user requesting the list of profiles
 697          * @return array|null the list of profiles or null if none available
 698          */
 699         public function getProfiles( $profileType, User $user = null ) {
 700                 return null;
 701         }
 702
 703         /**
 704          * Create a search field definition.
 705          * Specific search engines should override this method to create search fields.
 706          * @param string $name
 707          * @param int    $type One of the types in SearchIndexField::INDEX_TYPE_*
 708          * @return SearchIndexField
 709          * @since 1.28
 710          */
 711         public function makeSearchFieldMapping( $name, $type ) {
 712                 return new NullIndexField();
 713         }
 714
 715         /**
 716          * Get fields for search index
 717          * @since 1.28
 718          * @return SearchIndexField[] Index field definitions for all content handlers
 719          */
 720         public function getSearchIndexFields() {
 721                 $models = ContentHandler::getContentModels();
 722                 $fields = [];
 723                 $seenHandlers = new SplObjectStorage();
 724                 foreach ( $models as $model ) {
 725                         try {
 726                                 $handler = ContentHandler::getForModelID( $model );
 727                         }
 728                         catch ( MWUnknownContentModelException $e ) {
 729                                 // If we can find no handler, ignore it
 730                                 continue;
 731                         }
 732                         // Several models can have the same handler, so avoid processing it repeatedly
 733                         if ( $seenHandlers->contains( $handler ) ) {
 734                                 // We already did this one
 735                                 continue;
 736                         }
 737                         $seenHandlers->attach( $handler );
 738                         $handlerFields = $handler->getFieldsForSearchIndex( $this );
 739                         foreach ( $handlerFields as $fieldName => $fieldData ) {
 740                                 if ( empty( $fields[$fieldName] ) ) {
 741                                         $fields[$fieldName] = $fieldData;
 742                                 } else {
 743                                         // TODO: do we allow some clashes with the same type or reject all of them?
 744                                         $mergeDef = $fields[$fieldName]->merge( $fieldData );
 745                                         if ( !$mergeDef ) {
 746                                                 throw new InvalidArgumentException( "Duplicate field $fieldName for model $model" );
 747                                         }
 748                                         $fields[$fieldName] = $mergeDef;
 749                                 }
 750                         }
 751                 }
 752                 // Hook to allow extensions to produce search mapping fields
 753                 Hooks::run( 'SearchIndexFields', [ &$fields, $this ] );
 754                 return $fields;
 755         }
 756
 757         /**
 758          * Augment search results with extra data.
 759          *
 760          * @param SearchResultSet $resultSet
 761          */
 762         public function augmentSearchResults( SearchResultSet $resultSet ) {
 763                 $setAugmentors = [];
 764                 $rowAugmentors = [];
 765                 Hooks::run( "SearchResultsAugment", [ &$setAugmentors, &$rowAugmentors ] );
 766
 767                 if ( !$setAugmentors && !$rowAugmentors ) {
 768                         // We're done here
 769                         return;
 770                 }
 771
 772                 // Convert row augmentors to set augmentor
 773                 foreach ( $rowAugmentors as $name => $row ) {
 774                         if ( isset( $setAugmentors[$name] ) ) {
 775                                 throw new InvalidArgumentException( "Both row and set augmentors are defined for $name" );
 776                         }
 777                         $setAugmentors[$name] = new PerRowAugmentor( $row );
 778                 }
 779
 780                 foreach ( $setAugmentors as $name => $augmentor ) {
 781                         $data = $augmentor->augmentAll( $resultSet );
 782                         if ( $data ) {
 783                                 $resultSet->setAugmentedData( $name, $data );
 784                         }
 785                 }
 786         }
 787 }
 788
 789 /**
 790  * Dummy class to be used when non-supported Database engine is present.
 791  * @todo FIXME: Dummy class should probably try something at least mildly useful,
 792  * such as a LIKE search through titles.
 793  * @ingroup Search
 794  */
 795 class SearchEngineDummy extends SearchEngine {
 796         // no-op
 797 }