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 /**
  29  * Contain a class for special pages
  30  * @ingroup Search
  31  */
  32 class SearchEngine {
  33         var $limit = 10;
  34         var $offset = 0;
  35         var $prefix = '';
  36         var $searchTerms = array();
  37         var $namespaces = array( NS_MAIN );
  38         var $showRedirects = false;
  39
  40         /// Feature values
  41         protected $features = array();
  42
  43         /**
  44          * @var DatabaseBase
  45          */
  46         protected $db;
  47
  48         function __construct($db = null) {
  49                 if ( $db ) {
  50                         $this->db = $db;
  51                 } else {
  52                         $this->db = wfGetDB( DB_SLAVE );
  53                 }
  54         }
  55
  56         /**
  57          * Perform a full text search query and return a result set.
  58          * If title searches are not supported or disabled, return null.
  59          * STUB
  60          *
  61          * @param $term String: raw search term
  62          * @return SearchResultSet
  63          */
  64         function searchText( $term ) {
  65                 return null;
  66         }
  67
  68         /**
  69          * Perform a title-only search query and return a result set.
  70          * If title searches are not supported or disabled, return null.
  71          * STUB
  72          *
  73          * @param $term String: raw search term
  74          * @return SearchResultSet
  75          */
  76         function searchTitle( $term ) {
  77                 return null;
  78         }
  79
  80         /**
  81          * If this search backend can list/unlist redirects
  82          * @deprecated since 1.18 Call supports( 'list-redirects' );
  83          * @return bool
  84          */
  85         function acceptListRedirects() {
  86                 wfDeprecated( __METHOD__, '1.18' );
  87                 return $this->supports( 'list-redirects' );
  88         }
  89
  90         /**
  91          * @since 1.18
  92          * @param $feature String
  93          * @return Boolean
  94          */
  95         public function supports( $feature ) {
  96                 switch( $feature ) {
  97                 case 'list-redirects':
  98                         return true;
  99                 case 'title-suffix-filter':
 100                 default:
 101                         return false;
 102                 }
 103         }
 104
 105         /**
 106          * Way to pass custom data for engines
 107          * @since 1.18
 108          * @param $feature String
 109          * @param $data Mixed
 110          * @return bool
 111          */
 112         public function setFeatureData( $feature, $data ) {
 113                 $this->features[$feature] = $data;
 114         }
 115
 116         /**
 117          * When overridden in derived class, performs database-specific conversions
 118          * on text to be used for searching or updating search index.
 119          * Default implementation does nothing (simply returns $string).
 120          *
 121          * @param $string string: String to process
 122          * @return string
 123          */
 124         public function normalizeText( $string ) {
 125                 global $wgContLang;
 126
 127                 // Some languages such as Chinese require word segmentation
 128                 return $wgContLang->segmentByWord( $string );
 129         }
 130
 131         /**
 132          * Transform search term in cases when parts of the query came as different GET params (when supported)
 133          * e.g. for prefix queries: search=test&prefix=Main_Page/Archive -> test prefix:Main Page/Archive
 134          */
 135         function transformSearchTerm( $term ) {
 136                 return $term;
 137         }
 138
 139         /**
 140          * If an exact title match can be found, or a very slightly close match,
 141          * return the title. If no match, returns NULL.
 142          *
 143          * @param $searchterm String
 144          * @return Title
 145          */
 146         public static function getNearMatch( $searchterm ) {
 147                 $title = self::getNearMatchInternal( $searchterm );
 148
 149                 wfRunHooks( 'SearchGetNearMatchComplete', array( $searchterm, &$title ) );
 150                 return $title;
 151         }
 152
 153         /**
 154          * Do a near match (see SearchEngine::getNearMatch) and wrap it into a
 155          * SearchResultSet.
 156          *
 157          * @param $searchterm string
 158          * @return SearchResultSet
 159          */
 160         public static function getNearMatchResultSet( $searchterm ) {
 161                 return new SearchNearMatchResultSet( self::getNearMatch( $searchterm ) );
 162         }
 163
 164         /**
 165          * Really find the title match.
 166          * @return null|\Title
 167          */
 168         private static function getNearMatchInternal( $searchterm ) {
 169                 global $wgContLang, $wgEnableSearchContributorsByIP;
 170
 171                 $allSearchTerms = array( $searchterm );
 172
 173                 if ( $wgContLang->hasVariants() ) {
 174                         $allSearchTerms = array_merge( $allSearchTerms, $wgContLang->autoConvertToAllVariants( $searchterm ) );
 175                 }
 176
 177                 $titleResult = null;
 178                 if ( !wfRunHooks( 'SearchGetNearMatchBefore', array( $allSearchTerms, &$titleResult ) ) ) {
 179                         return $titleResult;
 180                 }
 181
 182                 foreach ( $allSearchTerms as $term ) {
 183
 184                         # Exact match? No need to look further.
 185                         $title = Title::newFromText( $term );
 186                         if ( is_null( $title ) ){
 187                                 return null;
 188                         }
 189
 190                         if ( $title->isSpecialPage() || $title->isExternal() || $title->exists() ) {
 191                                 return $title;
 192                         }
 193
 194                         # See if it still otherwise has content is some sane sense
 195                         $page = WikiPage::factory( $title );
 196                         if ( $page->hasViewableContent() ) {
 197                                 return $title;
 198                         }
 199
 200                         # Now try all lower case (i.e. first letter capitalized)
 201                         #
 202                         $title = Title::newFromText( $wgContLang->lc( $term ) );
 203                         if ( $title && $title->exists() ) {
 204                                 return $title;
 205                         }
 206
 207                         # Now try capitalized string
 208                         #
 209                         $title = Title::newFromText( $wgContLang->ucwords( $term ) );
 210                         if ( $title && $title->exists() ) {
 211                                 return $title;
 212                         }
 213
 214                         # Now try all upper case
 215                         #
 216                         $title = Title::newFromText( $wgContLang->uc( $term ) );
 217                         if ( $title && $title->exists() ) {
 218                                 return $title;
 219                         }
 220
 221                         # Now try Word-Caps-Breaking-At-Word-Breaks, for hyphenated names etc
 222                         $title = Title::newFromText( $wgContLang->ucwordbreaks( $term ) );
 223                         if ( $title && $title->exists() ) {
 224                                 return $title;
 225                         }
 226
 227                         // Give hooks a chance at better match variants
 228                         $title = null;
 229                         if ( !wfRunHooks( 'SearchGetNearMatch', array( $term, &$title ) ) ) {
 230                                 return $title;
 231                         }
 232                 }
 233
 234                 $title = Title::newFromText( $searchterm );
 235
 236
 237                 # Entering an IP address goes to the contributions page
 238                 if ( $wgEnableSearchContributorsByIP ) {
 239                         if ( ( $title->getNamespace() == NS_USER && User::isIP( $title->getText() ) )
 240                                 || User::isIP( trim( $searchterm ) ) ) {
 241                                 return SpecialPage::getTitleFor( 'Contributions', $title->getDBkey() );
 242                         }
 243                 }
 244
 245
 246                 # Entering a user goes to the user page whether it's there or not
 247                 if ( $title->getNamespace() == NS_USER ) {
 248                         return $title;
 249                 }
 250
 251                 # Go to images that exist even if there's no local page.
 252                 # There may have been a funny upload, or it may be on a shared
 253                 # file repository such as Wikimedia Commons.
 254                 if ( $title->getNamespace() == NS_FILE ) {
 255                         $image = wfFindFile( $title );
 256                         if ( $image ) {
 257                                 return $title;
 258                         }
 259                 }
 260
 261                 # MediaWiki namespace? Page may be "implied" if not customized.
 262                 # Just return it, with caps forced as the message system likes it.
 263                 if ( $title->getNamespace() == NS_MEDIAWIKI ) {
 264                         return Title::makeTitle( NS_MEDIAWIKI, $wgContLang->ucfirst( $title->getText() ) );
 265                 }
 266
 267                 # Quoted term? Try without the quotes...
 268                 $matches = array();
 269                 if ( preg_match( '/^"([^"]+)"$/', $searchterm, $matches ) ) {
 270                         return SearchEngine::getNearMatch( $matches[1] );
 271                 }
 272
 273                 return null;
 274         }
 275
 276         public static function legalSearchChars() {
 277                 return "A-Za-z_'.0-9\\x80-\\xFF\\-";
 278         }
 279
 280         /**
 281          * Set the maximum number of results to return
 282          * and how many to skip before returning the first.
 283          *
 284          * @param $limit Integer
 285          * @param $offset Integer
 286          */
 287         function setLimitOffset( $limit, $offset = 0 ) {
 288                 $this->limit = intval( $limit );
 289                 $this->offset = intval( $offset );
 290         }
 291
 292         /**
 293          * Set which namespaces the search should include.
 294          * Give an array of namespace index numbers.
 295          *
 296          * @param $namespaces Array
 297          */
 298         function setNamespaces( $namespaces ) {
 299                 $this->namespaces = $namespaces;
 300         }
 301
 302         /**
 303          * Parse some common prefixes: all (search everything)
 304          * or namespace names
 305          *
 306          * @param $query String
 307          * @return string
 308          */
 309         function replacePrefixes( $query ) {
 310                 global $wgContLang;
 311
 312                 $parsed = $query;
 313                 if ( strpos( $query, ':' ) === false ) { // nothing to do
 314                         wfRunHooks( 'SearchEngineReplacePrefixesComplete', array( $this, $query, &$parsed ) );
 315                         return $parsed;
 316                 }
 317
 318                 $allkeyword = wfMessage( 'searchall' )->inContentLanguage()->text() . ":";
 319                 if ( strncmp( $query, $allkeyword, strlen( $allkeyword ) ) == 0 ) {
 320                         $this->namespaces = null;
 321                         $parsed = substr( $query, strlen( $allkeyword ) );
 322                 } elseif ( strpos( $query, ':' ) !== false ) {
 323                         $prefix = substr( $query, 0, strpos( $query, ':' ) );
 324                         $index = $wgContLang->getNsIndex( $prefix );
 325                         if ( $index !== false ) {
 326                                 $this->namespaces = array( $index );
 327                                 $parsed = substr( $query, strlen( $prefix ) + 1 );
 328                         }
 329                 }
 330                 if ( trim( $parsed ) == '' )
 331                         $parsed = $query; // prefix was the whole query
 332
 333                 wfRunHooks( 'SearchEngineReplacePrefixesComplete', array( $this, $query, &$parsed ) );
 334
 335                 return $parsed;
 336         }
 337
 338         /**
 339          * Make a list of searchable namespaces and their canonical names.
 340          * @return Array
 341          */
 342         public static function searchableNamespaces() {
 343                 global $wgContLang;
 344                 $arr = array();
 345                 foreach ( $wgContLang->getNamespaces() as $ns => $name ) {
 346                         if ( $ns >= NS_MAIN ) {
 347                                 $arr[$ns] = $name;
 348                         }
 349                 }
 350
 351                 wfRunHooks( 'SearchableNamespaces', array( &$arr ) );
 352                 return $arr;
 353         }
 354
 355         /**
 356          * Extract default namespaces to search from the given user's
 357          * settings, returning a list of index numbers.
 358          *
 359          * @param $user User
 360          * @return Array
 361          */
 362         public static function userNamespaces( $user ) {
 363                 global $wgSearchEverythingOnlyLoggedIn;
 364
 365                 $searchableNamespaces = SearchEngine::searchableNamespaces();
 366
 367                 // get search everything preference, that can be set to be read for logged-in users
 368                 // it overrides other options
 369                 if ( !$wgSearchEverythingOnlyLoggedIn || $user->isLoggedIn() ) {
 370                         if ( $user->getOption( 'searcheverything' ) ) {
 371                                 return array_keys( $searchableNamespaces );
 372                         }
 373                 }
 374
 375                 $arr = array();
 376                 foreach ( $searchableNamespaces as $ns => $name ) {
 377                         if ( $user->getOption( 'searchNs' . $ns ) ) {
 378                                 $arr[] = $ns;
 379                         }
 380                 }
 381
 382                 return $arr;
 383         }
 384
 385         /**
 386          * Find snippet highlight settings for all users
 387          *
 388          * @return Array contextlines, contextchars
 389          */
 390         public static function userHighlightPrefs() {
 391                 $contextlines = 2; // Hardcode this. Old defaults sucked. :)
 392                 $contextchars = 75; // same as above.... :P
 393                 return array( $contextlines, $contextchars );
 394         }
 395
 396         /**
 397          * An array of namespaces indexes to be searched by default
 398          *
 399          * @return Array
 400          */
 401         public static function defaultNamespaces() {
 402                 global $wgNamespacesToBeSearchedDefault;
 403
 404                 return array_keys( $wgNamespacesToBeSearchedDefault, true );
 405         }
 406
 407         /**
 408          * Get a list of namespace names useful for showing in tooltips
 409          * and preferences
 410          *
 411          * @param $namespaces Array
 412          * @return array
 413          */
 414         public static function namespacesAsText( $namespaces ) {
 415                 global $wgContLang;
 416
 417                 $formatted = array_map( array( $wgContLang, 'getFormattedNsText' ), $namespaces );
 418                 foreach ( $formatted as $key => $ns ) {
 419                         if ( empty( $ns ) )
 420                                 $formatted[$key] = wfMessage( 'blanknamespace' )->text();
 421                 }
 422                 return $formatted;
 423         }
 424
 425         /**
 426          * Return the help namespaces to be shown on Special:Search
 427          *
 428          * @return Array
 429          */
 430         public static function helpNamespaces() {
 431                 global $wgNamespacesToBeSearchedHelp;
 432
 433                 return array_keys( $wgNamespacesToBeSearchedHelp, true );
 434         }
 435
 436         /**
 437          * Return a 'cleaned up' search string
 438          *
 439          * @param $text String
 440          * @return String
 441          */
 442         function filter( $text ) {
 443                 $lc = $this->legalSearchChars();
 444                 return trim( preg_replace( "/[^{$lc}]/", " ", $text ) );
 445         }
 446         /**
 447          * Load up the appropriate search engine class for the currently
 448          * active database backend, and return a configured instance.
 449          *
 450          * @return SearchEngine
 451          */
 452         public static function create() {
 453                 global $wgSearchType;
 454                 $dbr = null;
 455                 if ( $wgSearchType ) {
 456                         $class = $wgSearchType;
 457                 } else {
 458                         $dbr = wfGetDB( DB_SLAVE );
 459                         $class = $dbr->getSearchEngine();
 460                 }
 461                 $search = new $class( $dbr );
 462                 $search->setLimitOffset( 0, 0 );
 463                 return $search;
 464         }
 465
 466         /**
 467          * Create or update the search index record for the given page.
 468          * Title and text should be pre-processed.
 469          * STUB
 470          *
 471          * @param $id Integer
 472          * @param $title String
 473          * @param $text String
 474          */
 475         function update( $id, $title, $text ) {
 476                 // no-op
 477         }
 478
 479         /**
 480          * Update a search index record's title only.
 481          * Title should be pre-processed.
 482          * STUB
 483          *
 484          * @param $id Integer
 485          * @param $title String
 486          */
 487         function updateTitle( $id, $title ) {
 488                 // no-op
 489         }
 490
 491         /**
 492          * Get OpenSearch suggestion template
 493          *
 494          * @return String
 495          */
 496         public static function getOpenSearchTemplate() {
 497                 global $wgOpenSearchTemplate, $wgCanonicalServer;
 498                 if ( $wgOpenSearchTemplate ) {
 499                         return $wgOpenSearchTemplate;
 500                 } else {
 501                         $ns = implode( '|', SearchEngine::defaultNamespaces() );
 502                         if ( !$ns ) {
 503                                 $ns = "0";
 504                         }
 505                         return $wgCanonicalServer . wfScript( 'api' ) . '?action=opensearch&search={searchTerms}&namespace=' . $ns;
 506                 }
 507         }
 508 }
 509
 510 /**
 511  * @ingroup Search
 512  */
 513 class SearchResultSet {
 514         /**
 515          * Fetch an array of regular expression fragments for matching
 516          * the search terms as parsed by this engine in a text extract.
 517          * STUB
 518          *
 519          * @return Array
 520          */
 521         function termMatches() {
 522                 return array();
 523         }
 524
 525         function numRows() {
 526                 return 0;
 527         }
 528
 529         /**
 530          * Return true if results are included in this result set.
 531          * STUB
 532          *
 533          * @return Boolean
 534          */
 535         function hasResults() {
 536                 return false;
 537         }
 538
 539         /**
 540          * Some search modes return a total hit count for the query
 541          * in the entire article database. This may include pages
 542          * in namespaces that would not be matched on the given
 543          * settings.
 544          *
 545          * Return null if no total hits number is supported.
 546          *
 547          * @return Integer
 548          */
 549         function getTotalHits() {
 550                 return null;
 551         }
 552
 553         /**
 554          * Some search modes return a suggested alternate term if there are
 555          * no exact hits. Returns true if there is one on this set.
 556          *
 557          * @return Boolean
 558          */
 559         function hasSuggestion() {
 560                 return false;
 561         }
 562
 563         /**
 564          * @return String: suggested query, null if none
 565          */
 566         function getSuggestionQuery() {
 567                 return null;
 568         }
 569
 570         /**
 571          * @return String: HTML highlighted suggested query, '' if none
 572          */
 573         function getSuggestionSnippet() {
 574                 return '';
 575         }
 576
 577         /**
 578          * Return information about how and from where the results were fetched,
 579          * should be useful for diagnostics and debugging
 580          *
 581          * @return String
 582          */
 583         function getInfo() {
 584                 return null;
 585         }
 586
 587         /**
 588          * Return a result set of hits on other (multiple) wikis associated with this one
 589          *
 590          * @return SearchResultSet
 591          */
 592         function getInterwikiResults() {
 593                 return null;
 594         }
 595
 596         /**
 597          * Check if there are results on other wikis
 598          *
 599          * @return Boolean
 600          */
 601         function hasInterwikiResults() {
 602                 return $this->getInterwikiResults() != null;
 603         }
 604
 605         /**
 606          * Fetches next search result, or false.
 607          * STUB
 608          *
 609          * @return SearchResult
 610          */
 611         function next() {
 612                 return false;
 613         }
 614
 615         /**
 616          * Frees the result set, if applicable.
 617          */
 618         function free() {
 619                 // ...
 620         }
 621 }
 622
 623 /**
 624  * This class is used for different SQL-based search engines shipped with MediaWiki
 625  */
 626 class SqlSearchResultSet extends SearchResultSet {
 627
 628         protected $mResultSet;
 629
 630         function __construct( $resultSet, $terms ) {
 631                 $this->mResultSet = $resultSet;
 632                 $this->mTerms = $terms;
 633         }
 634
 635         function termMatches() {
 636                 return $this->mTerms;
 637         }
 638
 639         function numRows() {
 640                 if ( $this->mResultSet === false )
 641                         return false;
 642
 643                 return $this->mResultSet->numRows();
 644         }
 645
 646         function next() {
 647                 if ( $this->mResultSet === false )
 648                         return false;
 649
 650                 $row = $this->mResultSet->fetchObject();
 651                 if ( $row === false )
 652                         return false;
 653
 654                 return SearchResult::newFromRow( $row );
 655         }
 656
 657         function free() {
 658                 if ( $this->mResultSet === false )
 659                         return false;
 660
 661                 $this->mResultSet->free();
 662         }
 663 }
 664
 665 /**
 666  * @ingroup Search
 667  */
 668 class SearchResultTooMany {
 669         # # Some search engines may bail out if too many matches are found
 670 }
 671
 672
 673 /**
 674  * @todo FIXME: This class is horribly factored. It would probably be better to
 675  * have a useful base class to which you pass some standard information, then
 676  * let the fancy self-highlighters extend that.
 677  * @ingroup Search
 678  */
 679 class SearchResult {
 680
 681         /**
 682          * @var Revision
 683          */
 684         var $mRevision = null;
 685         var $mImage = null;
 686
 687         /**
 688          * @var Title
 689          */
 690         var $mTitle;
 691
 692         /**
 693          * @var String
 694          */
 695         var $mText;
 696
 697         /**
 698          * Return a new SearchResult and initializes it with a title.
 699          *
 700          * @param $title Title
 701          * @return SearchResult
 702          */
 703         public static function newFromTitle( $title ) {
 704                 $result = new self();
 705                 $result->initFromTitle( $title );
 706                 return $result;
 707         }
 708         /**
 709          * Return a new SearchResult and initializes it with a row.
 710          *
 711          * @param $row object
 712          * @return SearchResult
 713          */
 714         public static function newFromRow( $row ) {
 715                 $result = new self();
 716                 $result->initFromRow( $row );
 717                 return $result;
 718         }
 719
 720         public function __construct( $row = null ) {
 721                 if ( !is_null( $row ) ) {
 722                         // Backwards compatibility with pre-1.17 callers
 723                         $this->initFromRow( $row );
 724                 }
 725         }
 726
 727         /**
 728          * Initialize from a database row. Makes a Title and passes that to
 729          * initFromTitle.
 730          *
 731          * @param $row object
 732          */
 733         protected function initFromRow( $row ) {
 734                 $this->initFromTitle( Title::makeTitle( $row->page_namespace, $row->page_title ) );
 735         }
 736
 737         /**
 738          * Initialize from a Title and if possible initializes a corresponding
 739          * Revision and File.
 740          *
 741          * @param $title Title
 742          */
 743         protected function initFromTitle( $title ) {
 744                 $this->mTitle = $title;
 745                 if ( !is_null( $this->mTitle ) ) {
 746                         $id = false;
 747                         wfRunHooks( 'SearchResultInitFromTitle', array( $title, &$id ) );
 748                         $this->mRevision = Revision::newFromTitle(
 749                                 $this->mTitle, $id, Revision::READ_NORMAL );
 750                         if ( $this->mTitle->getNamespace() === NS_FILE )
 751                                 $this->mImage = wfFindFile( $this->mTitle );
 752                 }
 753         }
 754
 755         /**
 756          * Check if this is result points to an invalid title
 757          *
 758          * @return Boolean
 759          */
 760         function isBrokenTitle() {
 761                 if ( is_null( $this->mTitle ) )
 762                         return true;
 763                 return false;
 764         }
 765
 766         /**
 767          * Check if target page is missing, happens when index is out of date
 768          *
 769          * @return Boolean
 770          */
 771         function isMissingRevision() {
 772                 return !$this->mRevision && !$this->mImage;
 773         }
 774
 775         /**
 776          * @return Title
 777          */
 778         function getTitle() {
 779                 return $this->mTitle;
 780         }
 781
 782         /**
 783          * @return float|null if not supported
 784          */
 785         function getScore() {
 786                 return null;
 787         }
 788
 789         /**
 790          * Lazy initialization of article text from DB
 791          */
 792         protected function initText() {
 793                 if ( !isset( $this->mText ) ) {
 794                         if ( $this->mRevision != null )
 795                                 $this->mText = $this->mRevision->getText();
 796                         else // TODO: can we fetch raw wikitext for commons images?
 797                                 $this->mText = '';
 798
 799                 }
 800         }
 801
 802         /**
 803          * @param $terms Array: terms to highlight
 804          * @return String: highlighted text snippet, null (and not '') if not supported
 805          */
 806         function getTextSnippet( $terms ) {
 807                 global $wgUser, $wgAdvancedSearchHighlighting;
 808                 $this->initText();
 809                 list( $contextlines, $contextchars ) = SearchEngine::userHighlightPrefs( $wgUser );
 810                 $h = new SearchHighlighter();
 811                 if ( $wgAdvancedSearchHighlighting )
 812                         return $h->highlightText( $this->mText, $terms, $contextlines, $contextchars );
 813                 else
 814                         return $h->highlightSimple( $this->mText, $terms, $contextlines, $contextchars );
 815         }
 816
 817         /**
 818          * @param $terms Array: terms to highlight
 819          * @return String: highlighted title, '' if not supported
 820          */
 821         function getTitleSnippet( $terms ) {
 822                 return '';
 823         }
 824
 825         /**
 826          * @param $terms Array: terms to highlight
 827          * @return String: highlighted redirect name (redirect to this page), '' if none or not supported
 828          */
 829         function getRedirectSnippet( $terms ) {
 830                 return '';
 831         }
 832
 833         /**
 834          * @return Title object for the redirect to this page, null if none or not supported
 835          */
 836         function getRedirectTitle() {
 837                 return null;
 838         }
 839
 840         /**
 841          * @return string highlighted relevant section name, null if none or not supported
 842          */
 843         function getSectionSnippet() {
 844                 return '';
 845         }
 846
 847         /**
 848          * @return Title object (pagename+fragment) for the section, null if none or not supported
 849          */
 850         function getSectionTitle() {
 851                 return null;
 852         }
 853
 854         /**
 855          * @return String: timestamp
 856          */
 857         function getTimestamp() {
 858                 if ( $this->mRevision )
 859                         return $this->mRevision->getTimestamp();
 860                 elseif ( $this->mImage )
 861                         return $this->mImage->getTimestamp();
 862                 return '';
 863         }
 864
 865         /**
 866          * @return Integer: number of words
 867          */
 868         function getWordCount() {
 869                 $this->initText();
 870                 return str_word_count( $this->mText );
 871         }
 872
 873         /**
 874          * @return Integer: size in bytes
 875          */
 876         function getByteSize() {
 877                 $this->initText();
 878                 return strlen( $this->mText );
 879         }
 880
 881         /**
 882          * @return Boolean if hit has related articles
 883          */
 884         function hasRelated() {
 885                 return false;
 886         }
 887
 888         /**
 889          * @return String: interwiki prefix of the title (return iw even if title is broken)
 890          */
 891         function getInterwikiPrefix() {
 892                 return '';
 893         }
 894 }
 895 /**
 896  * A SearchResultSet wrapper for SearchEngine::getNearMatch
 897  */
 898 class SearchNearMatchResultSet extends SearchResultSet {
 899         private $fetched = false;
 900         /**
 901          * @param $match mixed Title if matched, else null
 902          */
 903         public function __construct( $match ) {
 904                 $this->result = $match;
 905         }
 906         public function hasResult() {
 907                 return (bool)$this->result;
 908         }
 909         public function numRows() {
 910                 return $this->hasResults() ? 1 : 0;
 911         }
 912         public function next() {
 913                 if ( $this->fetched || !$this->result ) {
 914                         return false;
 915                 }
 916                 $this->fetched = true;
 917                 return SearchResult::newFromTitle( $this->result );
 918         }
 919 }
 920
 921 /**
 922  * Highlight bits of wikitext
 923  *
 924  * @ingroup Search
 925  */
 926 class SearchHighlighter {
 927         var $mCleanWikitext = true;
 928
 929         function __construct( $cleanupWikitext = true ) {
 930                 $this->mCleanWikitext = $cleanupWikitext;
 931         }
 932
 933         /**
 934          * Default implementation of wikitext highlighting
 935          *
 936          * @param $text String
 937          * @param $terms Array: terms to highlight (unescaped)
 938          * @param $contextlines Integer
 939          * @param $contextchars Integer
 940          * @return String
 941          */
 942         public function highlightText( $text, $terms, $contextlines, $contextchars ) {
 943                 global $wgContLang;
 944                 global $wgSearchHighlightBoundaries;
 945                 $fname = __METHOD__;
 946
 947                 if ( $text == '' )
 948                         return '';
 949
 950                 // spli text into text + templates/links/tables
 951                 $spat = "/(\\{\\{)|(\\[\\[[^\\]:]+:)|(\n\\{\\|)";
 952                 // first capture group is for detecting nested templates/links/tables/references
 953                 $endPatterns = array(
 954                         1 => '/(\{\{)|(\}\})/', // template
 955                         2 => '/(\[\[)|(\]\])/', // image
 956                         3 => "/(\n\\{\\|)|(\n\\|\\})/" ); // table
 957
 958                 // @todo FIXME: This should prolly be a hook or something
 959                 if ( function_exists( 'wfCite' ) ) {
 960                         $spat .= '|(<ref>)'; // references via cite extension
 961                         $endPatterns[4] = '/(<ref>)|(<\/ref>)/';
 962                 }
 963                 $spat .= '/';
 964                 $textExt = array(); // text extracts
 965                 $otherExt = array();  // other extracts
 966                 wfProfileIn( "$fname-split" );
 967                 $start = 0;
 968                 $textLen = strlen( $text );
 969                 $count = 0; // sequence number to maintain ordering
 970                 while ( $start < $textLen ) {
 971                         // find start of template/image/table
 972                         if ( preg_match( $spat, $text, $matches, PREG_OFFSET_CAPTURE, $start ) ) {
 973                                 $epat = '';
 974                                 foreach ( $matches as $key => $val ) {
 975                                         if ( $key > 0 && $val[1] != - 1 ) {
 976                                                 if ( $key == 2 ) {
 977                                                         // see if this is an image link
 978                                                         $ns = substr( $val[0], 2, - 1 );
 979                                                         if ( $wgContLang->getNsIndex( $ns ) != NS_FILE )
 980                                                                 break;
 981
 982                                                 }
 983                                                 $epat = $endPatterns[$key];
 984                                                 $this->splitAndAdd( $textExt, $count, substr( $text, $start, $val[1] - $start ) );
 985                                                 $start = $val[1];
 986                                                 break;
 987                                         }
 988                                 }
 989                                 if ( $epat ) {
 990                                         // find end (and detect any nested elements)
 991                                         $level = 0;
 992                                         $offset = $start + 1;
 993                                         $found = false;
 994                                         while ( preg_match( $epat, $text, $endMatches, PREG_OFFSET_CAPTURE, $offset ) ) {
 995                                                 if ( array_key_exists( 2, $endMatches ) ) {
 996                                                         // found end
 997                                                         if ( $level == 0 ) {
 998                                                                 $len = strlen( $endMatches[2][0] );
 999                                                                 $off = $endMatches[2][1];
1000                                                                 $this->splitAndAdd( $otherExt, $count,
1001                                                                         substr( $text, $start, $off + $len  - $start ) );
1002                                                                 $start = $off + $len;
1003                                                                 $found = true;
1004                                                                 break;
1005                                                         } else {
1006                                                                 // end of nested element
1007                                                                 $level -= 1;
1008                                                         }
1009                                                 } else {
1010                                                         // nested
1011                                                         $level += 1;
1012                                                 }
1013                                                 $offset = $endMatches[0][1] + strlen( $endMatches[0][0] );
1014                                         }
1015                                         if ( ! $found ) {
1016                                                 // couldn't find appropriate closing tag, skip
1017                                                 $this->splitAndAdd( $textExt, $count, substr( $text, $start, strlen( $matches[0][0] ) ) );
1018                                                 $start += strlen( $matches[0][0] );
1019                                         }
1020                                         continue;
1021                                 }
1022                         }
1023                         // else: add as text extract
1024                         $this->splitAndAdd( $textExt, $count, substr( $text, $start ) );
1025                         break;
1026                 }
1027
1028                 $all = $textExt + $otherExt; // these have disjunct key sets
1029
1030                 wfProfileOut( "$fname-split" );
1031
1032                 // prepare regexps
1033                 foreach ( $terms as $index => $term ) {
1034                         // manually do upper/lowercase stuff for utf-8 since PHP won't do it
1035                         if ( preg_match( '/[\x80-\xff]/', $term ) ) {
1036                                 $terms[$index] = preg_replace_callback( '/./us', array( $this, 'caseCallback' ), $terms[$index] );
1037                         } else {
1038                                 $terms[$index] = $term;
1039                         }
1040                 }
1041                 $anyterm = implode( '|', $terms );
1042                 $phrase = implode( "$wgSearchHighlightBoundaries+", $terms );
1043
1044                 // @todo FIXME: A hack to scale contextchars, a correct solution
1045                 // would be to have contextchars actually be char and not byte
1046                 // length, and do proper utf-8 substrings and lengths everywhere,
1047                 // but PHP is making that very hard and unclean to implement :(
1048                 $scale = strlen( $anyterm ) / mb_strlen( $anyterm );
1049                 $contextchars = intval( $contextchars * $scale );
1050
1051                 $patPre = "(^|$wgSearchHighlightBoundaries)";
1052                 $patPost = "($wgSearchHighlightBoundaries|$)";
1053
1054                 $pat1 = "/(" . $phrase . ")/ui";
1055                 $pat2 = "/$patPre(" . $anyterm . ")$patPost/ui";
1056
1057                 wfProfileIn( "$fname-extract" );
1058
1059                 $left = $contextlines;
1060
1061                 $snippets = array();
1062                 $offsets = array();
1063
1064                 // show beginning only if it contains all words
1065                 $first = 0;
1066                 $firstText = '';
1067                 foreach ( $textExt as $index => $line ) {
1068                         if ( strlen( $line ) > 0 && $line[0] != ';' && $line[0] != ':' ) {
1069                                 $firstText = $this->extract( $line, 0, $contextchars * $contextlines );
1070                                 $first = $index;
1071                                 break;
1072                         }
1073                 }
1074                 if ( $firstText ) {
1075                         $succ = true;
1076                         // check if first text contains all terms
1077                         foreach ( $terms as $term ) {
1078                                 if ( ! preg_match( "/$patPre" . $term . "$patPost/ui", $firstText ) ) {
1079                                         $succ = false;
1080                                         break;
1081                                 }
1082                         }
1083                         if ( $succ ) {
1084                                 $snippets[$first] = $firstText;
1085                                 $offsets[$first] = 0;
1086                         }
1087                 }
1088                 if ( ! $snippets ) {
1089                         // match whole query on text
1090                         $this->process( $pat1, $textExt, $left, $contextchars, $snippets, $offsets );
1091                         // match whole query on templates/tables/images
1092                         $this->process( $pat1, $otherExt, $left, $contextchars, $snippets, $offsets );
1093                         // match any words on text
1094                         $this->process( $pat2, $textExt, $left, $contextchars, $snippets, $offsets );
1095                         // match any words on templates/tables/images
1096                         $this->process( $pat2, $otherExt, $left, $contextchars, $snippets, $offsets );
1097
1098                         ksort( $snippets );
1099                 }
1100
1101                 // add extra chars to each snippet to make snippets constant size
1102                 $extended = array();
1103                 if ( count( $snippets ) == 0 ) {
1104                         // couldn't find the target words, just show beginning of article
1105                         if ( array_key_exists( $first, $all ) ) {
1106                                 $targetchars = $contextchars * $contextlines;
1107                                 $snippets[$first] = '';
1108                                 $offsets[$first] = 0;
1109                         }
1110                 } else {
1111                         // if begin of the article contains the whole phrase, show only that !!
1112                         if ( array_key_exists( $first, $snippets ) && preg_match( $pat1, $snippets[$first] )
1113                                 && $offsets[$first] < $contextchars * 2 ) {
1114                                 $snippets = array ( $first => $snippets[$first] );
1115                         }
1116
1117                         // calc by how much to extend existing snippets
1118                         $targetchars = intval( ( $contextchars * $contextlines ) / count ( $snippets ) );
1119                 }
1120
1121                 foreach ( $snippets as $index => $line ) {
1122                         $extended[$index] = $line;
1123                         $len = strlen( $line );
1124                         if ( $len < $targetchars - 20 ) {
1125                                 // complete this line
1126                                 if ( $len < strlen( $all[$index] ) ) {
1127                                         $extended[$index] = $this->extract( $all[$index], $offsets[$index], $offsets[$index] + $targetchars, $offsets[$index] );
1128                                         $len = strlen( $extended[$index] );
1129                                 }
1130
1131                                 // add more lines
1132                                 $add = $index + 1;
1133                                 while ( $len < $targetchars - 20
1134                                            && array_key_exists( $add, $all )
1135                                            && !array_key_exists( $add, $snippets ) ) {
1136                                         $offsets[$add] = 0;
1137                                         $tt = "\n" . $this->extract( $all[$add], 0, $targetchars - $len, $offsets[$add] );
1138                                         $extended[$add] = $tt;
1139                                         $len += strlen( $tt );
1140                                         $add++;
1141                                 }
1142                         }
1143                 }
1144
1145                 // $snippets = array_map('htmlspecialchars', $extended);
1146                 $snippets = $extended;
1147                 $last = - 1;
1148                 $extract = '';
1149                 foreach ( $snippets as $index => $line ) {
1150                         if ( $last == - 1 )
1151                                 $extract .= $line; // first line
1152                         elseif ( $last + 1 == $index && $offsets[$last] + strlen( $snippets[$last] ) >= strlen( $all[$last] ) )
1153                                 $extract .= " " . $line; // continous lines
1154                         else
1155                                 $extract .= '<b> ... </b>' . $line;
1156
1157                         $last = $index;
1158                 }
1159                 if ( $extract )
1160                         $extract .= '<b> ... </b>';
1161
1162                 $processed = array();
1163                 foreach ( $terms as $term ) {
1164                         if ( ! isset( $processed[$term] ) ) {
1165                                 $pat3 = "/$patPre(" . $term . ")$patPost/ui"; // highlight word
1166                                 $extract = preg_replace( $pat3,
1167                                         "\\1<span class='searchmatch'>\\2</span>\\3", $extract );
1168                                 $processed[$term] = true;
1169                         }
1170                 }
1171
1172                 wfProfileOut( "$fname-extract" );
1173
1174                 return $extract;
1175         }
1176
1177         /**
1178          * Split text into lines and add it to extracts array
1179          *
1180          * @param $extracts Array: index -> $line
1181          * @param $count Integer
1182          * @param $text String
1183          */
1184         function splitAndAdd( &$extracts, &$count, $text ) {
1185                 $split = explode( "\n", $this->mCleanWikitext ? $this->removeWiki( $text ) : $text );
1186                 foreach ( $split as $line ) {
1187                         $tt = trim( $line );
1188                         if ( $tt )
1189                                 $extracts[$count++] = $tt;
1190                 }
1191         }
1192
1193         /**
1194          * Do manual case conversion for non-ascii chars
1195          *
1196          * @param $matches Array
1197          * @return string
1198          */
1199         function caseCallback( $matches ) {
1200                 global $wgContLang;
1201                 if ( strlen( $matches[0] ) > 1 ) {
1202                         return '[' . $wgContLang->lc( $matches[0] ) . $wgContLang->uc( $matches[0] ) . ']';
1203                 } else {
1204                         return $matches[0];
1205                 }
1206         }
1207
1208         /**
1209          * Extract part of the text from start to end, but by
1210          * not chopping up words
1211          * @param $text String
1212          * @param $start Integer
1213          * @param $end Integer
1214          * @param $posStart Integer: (out) actual start position
1215          * @param $posEnd Integer: (out) actual end position
1216          * @return String
1217          */
1218         function extract( $text, $start, $end, &$posStart = null, &$posEnd = null ) {
1219                 if ( $start != 0 ) {
1220                         $start = $this->position( $text, $start, 1 );
1221                 }
1222                 if ( $end >= strlen( $text ) ) {
1223                         $end = strlen( $text );
1224                 } else {
1225                         $end = $this->position( $text, $end );
1226                 }
1227
1228                 if ( !is_null( $posStart ) ) {
1229                         $posStart = $start;
1230                 }
1231                 if ( !is_null( $posEnd ) ) {
1232                         $posEnd = $end;
1233                 }
1234
1235                 if ( $end > $start )  {
1236                         return substr( $text, $start, $end - $start );
1237                 } else {
1238                         return '';
1239                 }
1240         }
1241
1242         /**
1243          * Find a nonletter near a point (index) in the text
1244          *
1245          * @param $text String
1246          * @param $point Integer
1247          * @param $offset Integer: offset to found index
1248          * @return Integer: nearest nonletter index, or beginning of utf8 char if none
1249          */
1250         function position( $text, $point, $offset = 0 ) {
1251                 $tolerance = 10;
1252                 $s = max( 0, $point - $tolerance );
1253                 $l = min( strlen( $text ), $point + $tolerance ) - $s;
1254                 $m = array();
1255                 if ( preg_match( '/[ ,.!?~!@#$%^&*\(\)+=\-\\\|\[\]"\'<>]/', substr( $text, $s, $l ), $m, PREG_OFFSET_CAPTURE ) ) {
1256                         return $m[0][1] + $s + $offset;
1257                 } else {
1258                         // check if point is on a valid first UTF8 char
1259                         $char = ord( $text[$point] );
1260                         while ( $char >= 0x80 && $char < 0xc0 ) {
1261                                 // skip trailing bytes
1262                                 $point++;
1263                                 if ( $point >= strlen( $text ) )
1264                                         return strlen( $text );
1265                                 $char = ord( $text[$point] );
1266                         }
1267                         return $point;
1268
1269                 }
1270         }
1271
1272         /**
1273          * Search extracts for a pattern, and return snippets
1274          *
1275          * @param $pattern String: regexp for matching lines
1276          * @param $extracts Array: extracts to search
1277          * @param $linesleft Integer: number of extracts to make
1278          * @param $contextchars Integer: length of snippet
1279          * @param $out Array: map for highlighted snippets
1280          * @param $offsets Array: map of starting points of snippets
1281          * @protected
1282          */
1283         function process( $pattern, $extracts, &$linesleft, &$contextchars, &$out, &$offsets ) {
1284                 if ( $linesleft == 0 )
1285                         return; // nothing to do
1286                 foreach ( $extracts as $index => $line ) {
1287                         if ( array_key_exists( $index, $out ) )
1288                                 continue; // this line already highlighted
1289
1290                         $m = array();
1291                         if ( !preg_match( $pattern, $line, $m, PREG_OFFSET_CAPTURE ) )
1292                                 continue;
1293
1294                         $offset = $m[0][1];
1295                         $len = strlen( $m[0][0] );
1296                         if ( $offset + $len < $contextchars )
1297                                 $begin = 0;
1298                         elseif ( $len > $contextchars )
1299                                 $begin = $offset;
1300                         else
1301                                 $begin = $offset + intval( ( $len - $contextchars ) / 2 );
1302
1303                         $end = $begin + $contextchars;
1304
1305                         $posBegin = $begin;
1306                         // basic snippet from this line
1307                         $out[$index] = $this->extract( $line, $begin, $end, $posBegin );
1308                         $offsets[$index] = $posBegin;
1309                         $linesleft--;
1310                         if ( $linesleft == 0 )
1311                                 return;
1312                 }
1313         }
1314
1315         /**
1316          * Basic wikitext removal
1317          * @protected
1318          * @return mixed
1319          */
1320         function removeWiki( $text ) {
1321                 $fname = __METHOD__;
1322                 wfProfileIn( $fname );
1323
1324                 // $text = preg_replace("/'{2,5}/", "", $text);
1325                 // $text = preg_replace("/\[[a-z]+:\/\/[^ ]+ ([^]]+)\]/", "\\2", $text);
1326                 // $text = preg_replace("/\[\[([^]|]+)\]\]/", "\\1", $text);
1327                 // $text = preg_replace("/\[\[([^]]+\|)?([^|]]+)\]\]/", "\\2", $text);
1328                 // $text = preg_replace("/\\{\\|(.*?)\\|\\}/", "", $text);
1329                 // $text = preg_replace("/\\[\\[[A-Za-z_-]+:([^|]+?)\\]\\]/", "", $text);
1330                 $text = preg_replace( "/\\{\\{([^|]+?)\\}\\}/", "", $text );
1331                 $text = preg_replace( "/\\{\\{([^|]+\\|)(.*?)\\}\\}/", "\\2", $text );
1332                 $text = preg_replace( "/\\[\\[([^|]+?)\\]\\]/", "\\1", $text );
1333                 $text = preg_replace_callback( "/\\[\\[([^|]+\\|)(.*?)\\]\\]/", array( $this, 'linkReplace' ), $text );
1334                 // $text = preg_replace("/\\[\\[([^|]+\\|)(.*?)\\]\\]/", "\\2", $text);
1335                 $text = preg_replace( "/<\/?[^>]+>/", "", $text );
1336                 $text = preg_replace( "/'''''/", "", $text );
1337                 $text = preg_replace( "/('''|<\/?[iIuUbB]>)/", "", $text );
1338                 $text = preg_replace( "/''/", "", $text );
1339
1340                 wfProfileOut( $fname );
1341                 return $text;
1342         }
1343
1344         /**
1345          * callback to replace [[target|caption]] kind of links, if
1346          * the target is category or image, leave it
1347          *
1348          * @param $matches Array
1349          */
1350         function linkReplace( $matches ) {
1351                 $colon = strpos( $matches[1], ':' );
1352                 if ( $colon === false )
1353                         return $matches[2]; // replace with caption
1354                 global $wgContLang;
1355                 $ns = substr( $matches[1], 0, $colon );
1356                 $index = $wgContLang->getNsIndex( $ns );
1357                 if ( $index !== false && ( $index == NS_FILE || $index == NS_CATEGORY ) )
1358                         return $matches[0]; // return the whole thing
1359                 else
1360                         return $matches[2];
1361
1362         }
1363
1364         /**
1365          * Simple & fast snippet extraction, but gives completely unrelevant
1366          * snippets
1367          *
1368          * @param $text String
1369          * @param $terms Array
1370          * @param $contextlines Integer
1371          * @param $contextchars Integer
1372          * @return String
1373          */
1374         public function highlightSimple( $text, $terms, $contextlines, $contextchars ) {
1375                 global $wgContLang;
1376                 $fname = __METHOD__;
1377
1378                 $lines = explode( "\n", $text );
1379
1380                 $terms = implode( '|', $terms );
1381                 $max = intval( $contextchars ) + 1;
1382                 $pat1 = "/(.*)($terms)(.{0,$max})/i";
1383
1384                 $lineno = 0;
1385
1386                 $extract = "";
1387                 wfProfileIn( "$fname-extract" );
1388                 foreach ( $lines as $line ) {
1389                         if ( 0 == $contextlines ) {
1390                                 break;
1391                         }
1392                         ++$lineno;
1393                         $m = array();
1394                         if ( ! preg_match( $pat1, $line, $m ) ) {
1395                                 continue;
1396                         }
1397                         --$contextlines;
1398                         // truncate function changes ... to relevant i18n message.
1399                         $pre = $wgContLang->truncate( $m[1], - $contextchars, '...', false );
1400
1401                         if ( count( $m ) < 3 ) {
1402                                 $post = '';
1403                         } else {
1404                                 $post = $wgContLang->truncate( $m[3], $contextchars, '...', false );
1405                         }
1406
1407                         $found = $m[2];
1408
1409                         $line = htmlspecialchars( $pre . $found . $post );
1410                         $pat2 = '/(' . $terms . ")/i";
1411                         $line = preg_replace( $pat2,
1412                           "<span class='searchmatch'>\\1</span>", $line );
1413
1414                         $extract .= "${line}\n";
1415                 }
1416                 wfProfileOut( "$fname-extract" );
1417
1418                 return $extract;
1419         }
1420
1421 }
1422
1423 /**
1424  * Dummy class to be used when non-supported Database engine is present.
1425  * @todo FIXME: Dummy class should probably try something at least mildly useful,
1426  * such as a LIKE search through titles.
1427  * @ingroup Search
1428  */
1429 class SearchEngineDummy extends SearchEngine {
1430         // no-op
1431 }