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