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         protected $showSuggestion = true;
  40
  41         /// Feature values
  42         protected $features = array();
  43
  44         /**
  45          * Perform a full text search query and return a result set.
  46          * If title searches are not supported or disabled, return null.
  47          * STUB
  48          *
  49          * @param string $term raw search term
  50          * @return SearchResultSet|Status|null
  51          */
  52         function searchText( $term ) {
  53                 return null;
  54         }
  55
  56         /**
  57          * Perform a title-only search query and return a result set.
  58          * If title searches are not supported or disabled, return null.
  59          * STUB
  60          *
  61          * @param string $term raw search term
  62          * @return SearchResultSet|null
  63          */
  64         function searchTitle( $term ) {
  65                 return null;
  66         }
  67
  68         /**
  69          * @since 1.18
  70          * @param $feature String
  71          * @return Boolean
  72          */
  73         public function supports( $feature ) {
  74                 switch ( $feature ) {
  75                 case 'list-redirects':
  76                 case 'search-update':
  77                         return true;
  78                 case 'title-suffix-filter':
  79                 default:
  80                         return false;
  81                 }
  82         }
  83
  84         /**
  85          * Way to pass custom data for engines
  86          * @since 1.18
  87          * @param $feature String
  88          * @param $data Mixed
  89          * @return bool
  90          */
  91         public function setFeatureData( $feature, $data ) {
  92                 $this->features[$feature] = $data;
  93         }
  94
  95         /**
  96          * When overridden in derived class, performs database-specific conversions
  97          * on text to be used for searching or updating search index.
  98          * Default implementation does nothing (simply returns $string).
  99          *
 100          * @param string $string String to process
 101          * @return string
 102          */
 103         public function normalizeText( $string ) {
 104                 global $wgContLang;
 105
 106                 // Some languages such as Chinese require word segmentation
 107                 return $wgContLang->segmentByWord( $string );
 108         }
 109
 110         /**
 111          * Transform search term in cases when parts of the query came as different GET params (when supported)
 112          * e.g. for prefix queries: search=test&prefix=Main_Page/Archive -> test prefix:Main Page/Archive
 113          */
 114         function transformSearchTerm( $term ) {
 115                 return $term;
 116         }
 117
 118         /**
 119          * If an exact title match can be found, or a very slightly close match,
 120          * return the title. If no match, returns NULL.
 121          *
 122          * @param $searchterm String
 123          * @return Title
 124          */
 125         public static function getNearMatch( $searchterm ) {
 126                 $title = self::getNearMatchInternal( $searchterm );
 127
 128                 wfRunHooks( 'SearchGetNearMatchComplete', array( $searchterm, &$title ) );
 129                 return $title;
 130         }
 131
 132         /**
 133          * Do a near match (see SearchEngine::getNearMatch) and wrap it into a
 134          * SearchResultSet.
 135          *
 136          * @param $searchterm string
 137          * @return SearchResultSet
 138          */
 139         public static function getNearMatchResultSet( $searchterm ) {
 140                 return new SearchNearMatchResultSet( self::getNearMatch( $searchterm ) );
 141         }
 142
 143         /**
 144          * Really find the title match.
 145          * @return null|Title
 146          */
 147         private static function getNearMatchInternal( $searchterm ) {
 148                 global $wgContLang, $wgEnableSearchContributorsByIP;
 149
 150                 $allSearchTerms = array( $searchterm );
 151
 152                 if ( $wgContLang->hasVariants() ) {
 153                         $allSearchTerms = array_merge( $allSearchTerms, $wgContLang->autoConvertToAllVariants( $searchterm ) );
 154                 }
 155
 156                 $titleResult = null;
 157                 if ( !wfRunHooks( 'SearchGetNearMatchBefore', array( $allSearchTerms, &$titleResult ) ) ) {
 158                         return $titleResult;
 159                 }
 160
 161                 foreach ( $allSearchTerms as $term ) {
 162
 163                         # Exact match? No need to look further.
 164                         $title = Title::newFromText( $term );
 165                         if ( is_null( $title ) ) {
 166                                 return null;
 167                         }
 168
 169                         # Try files if searching in the Media: namespace
 170                         if ( $title->getNamespace() == NS_MEDIA ) {
 171                                 $title = Title::makeTitle( NS_FILE, $title->getText() );
 172                         }
 173
 174                         if ( $title->isSpecialPage() || $title->isExternal() || $title->exists() ) {
 175                                 return $title;
 176                         }
 177
 178                         # See if it still otherwise has content is some sane sense
 179                         $page = WikiPage::factory( $title );
 180                         if ( $page->hasViewableContent() ) {
 181                                 return $title;
 182                         }
 183
 184                         if ( !wfRunHooks( 'SearchAfterNoDirectMatch', array( $term, &$title ) ) ) {
 185                                 return $title;
 186                         }
 187
 188                         # Now try all lower case (i.e. first letter capitalized)
 189                         $title = Title::newFromText( $wgContLang->lc( $term ) );
 190                         if ( $title && $title->exists() ) {
 191                                 return $title;
 192                         }
 193
 194                         # Now try capitalized string
 195                         $title = Title::newFromText( $wgContLang->ucwords( $term ) );
 196                         if ( $title && $title->exists() ) {
 197                                 return $title;
 198                         }
 199
 200                         # Now try all upper case
 201                         $title = Title::newFromText( $wgContLang->uc( $term ) );
 202                         if ( $title && $title->exists() ) {
 203                                 return $title;
 204                         }
 205
 206                         # Now try Word-Caps-Breaking-At-Word-Breaks, for hyphenated names etc
 207                         $title = Title::newFromText( $wgContLang->ucwordbreaks( $term ) );
 208                         if ( $title && $title->exists() ) {
 209                                 return $title;
 210                         }
 211
 212                         // Give hooks a chance at better match variants
 213                         $title = null;
 214                         if ( !wfRunHooks( 'SearchGetNearMatch', array( $term, &$title ) ) ) {
 215                                 return $title;
 216                         }
 217                 }
 218
 219                 $title = Title::newFromText( $searchterm );
 220
 221                 # Entering an IP address goes to the contributions page
 222                 if ( $wgEnableSearchContributorsByIP ) {
 223                         if ( ( $title->getNamespace() == NS_USER && User::isIP( $title->getText() ) )
 224                                 || User::isIP( trim( $searchterm ) ) ) {
 225                                 return SpecialPage::getTitleFor( 'Contributions', $title->getDBkey() );
 226                         }
 227                 }
 228
 229                 # Entering a user goes to the user page whether it's there or not
 230                 if ( $title->getNamespace() == NS_USER ) {
 231                         return $title;
 232                 }
 233
 234                 # Go to images that exist even if there's no local page.
 235                 # There may have been a funny upload, or it may be on a shared
 236                 # file repository such as Wikimedia Commons.
 237                 if ( $title->getNamespace() == NS_FILE ) {
 238                         $image = wfFindFile( $title );
 239                         if ( $image ) {
 240                                 return $title;
 241                         }
 242                 }
 243
 244                 # MediaWiki namespace? Page may be "implied" if not customized.
 245                 # Just return it, with caps forced as the message system likes it.
 246                 if ( $title->getNamespace() == NS_MEDIAWIKI ) {
 247                         return Title::makeTitle( NS_MEDIAWIKI, $wgContLang->ucfirst( $title->getText() ) );
 248                 }
 249
 250                 # Quoted term? Try without the quotes...
 251                 $matches = array();
 252                 if ( preg_match( '/^"([^"]+)"$/', $searchterm, $matches ) ) {
 253                         return SearchEngine::getNearMatch( $matches[1] );
 254                 }
 255
 256                 return null;
 257         }
 258
 259         public static function legalSearchChars() {
 260                 return "A-Za-z_'.0-9\\x80-\\xFF\\-";
 261         }
 262
 263         /**
 264          * Set the maximum number of results to return
 265          * and how many to skip before returning the first.
 266          *
 267          * @param $limit Integer
 268          * @param $offset Integer
 269          */
 270         function setLimitOffset( $limit, $offset = 0 ) {
 271                 $this->limit = intval( $limit );
 272                 $this->offset = intval( $offset );
 273         }
 274
 275         /**
 276          * Set which namespaces the search should include.
 277          * Give an array of namespace index numbers.
 278          *
 279          * @param $namespaces Array
 280          */
 281         function setNamespaces( $namespaces ) {
 282                 $this->namespaces = $namespaces;
 283         }
 284
 285         /**
 286          * Set whether the searcher should try to build a suggestion.  Note: some searchers
 287          * don't support building a suggestion in the first place and others don't respect
 288          * this flag.
 289          *
 290          * @param boolean $showSuggestion should the searcher try to build suggestions
 291          */
 292         function setShowSuggestion( $showSuggestion ) {
 293                 $this->showSuggestion = $showSuggestion;
 294         }
 295
 296         /**
 297          * Parse some common prefixes: all (search everything)
 298          * or namespace names
 299          *
 300          * @param $query String
 301          * @return string
 302          */
 303         function replacePrefixes( $query ) {
 304                 global $wgContLang;
 305
 306                 $parsed = $query;
 307                 if ( strpos( $query, ':' ) === false ) { // nothing to do
 308                         wfRunHooks( 'SearchEngineReplacePrefixesComplete', array( $this, $query, &$parsed ) );
 309                         return $parsed;
 310                 }
 311
 312                 $allkeyword = wfMessage( 'searchall' )->inContentLanguage()->text() . ":";
 313                 if ( strncmp( $query, $allkeyword, strlen( $allkeyword ) ) == 0 ) {
 314                         $this->namespaces = null;
 315                         $parsed = substr( $query, strlen( $allkeyword ) );
 316                 } elseif ( strpos( $query, ':' ) !== false ) {
 317                         $prefix = str_replace( ' ', '_', substr( $query, 0, strpos( $query, ':' ) ) );
 318                         $index = $wgContLang->getNsIndex( $prefix );
 319                         if ( $index !== false ) {
 320                                 $this->namespaces = array( $index );
 321                                 $parsed = substr( $query, strlen( $prefix ) + 1 );
 322                         }
 323                 }
 324                 if ( trim( $parsed ) == '' ) {
 325                         $parsed = $query; // prefix was the whole query
 326                 }
 327
 328                 wfRunHooks( 'SearchEngineReplacePrefixesComplete', array( $this, $query, &$parsed ) );
 329
 330                 return $parsed;
 331         }
 332
 333         /**
 334          * Make a list of searchable namespaces and their canonical names.
 335          * @return Array
 336          */
 337         public static function searchableNamespaces() {
 338                 global $wgContLang;
 339                 $arr = array();
 340                 foreach ( $wgContLang->getNamespaces() as $ns => $name ) {
 341                         if ( $ns >= NS_MAIN ) {
 342                                 $arr[$ns] = $name;
 343                         }
 344                 }
 345
 346                 wfRunHooks( 'SearchableNamespaces', array( &$arr ) );
 347                 return $arr;
 348         }
 349
 350         /**
 351          * Extract default namespaces to search from the given user's
 352          * settings, returning a list of index numbers.
 353          *
 354          * @param $user User
 355          * @return Array
 356          */
 357         public static function userNamespaces( $user ) {
 358                 global $wgSearchEverythingOnlyLoggedIn;
 359
 360                 $searchableNamespaces = SearchEngine::searchableNamespaces();
 361
 362                 // get search everything preference, that can be set to be read for logged-in users
 363                 // it overrides other options
 364                 if ( !$wgSearchEverythingOnlyLoggedIn || $user->isLoggedIn() ) {
 365                         if ( $user->getOption( 'searcheverything' ) ) {
 366                                 return array_keys( $searchableNamespaces );
 367                         }
 368                 }
 369
 370                 $arr = array();
 371                 foreach ( $searchableNamespaces as $ns => $name ) {
 372                         if ( $user->getOption( 'searchNs' . $ns ) ) {
 373                                 $arr[] = $ns;
 374                         }
 375                 }
 376
 377                 return $arr;
 378         }
 379
 380         /**
 381          * Find snippet highlight settings for all users
 382          *
 383          * @return Array contextlines, contextchars
 384          */
 385         public static function userHighlightPrefs() {
 386                 $contextlines = 2; // Hardcode this. Old defaults sucked. :)
 387                 $contextchars = 75; // same as above.... :P
 388                 return array( $contextlines, $contextchars );
 389         }
 390
 391         /**
 392          * An array of namespaces indexes to be searched by default
 393          *
 394          * @return Array
 395          */
 396         public static function defaultNamespaces() {
 397                 global $wgNamespacesToBeSearchedDefault;
 398
 399                 return array_keys( $wgNamespacesToBeSearchedDefault, true );
 400         }
 401
 402         /**
 403          * Get a list of namespace names useful for showing in tooltips
 404          * and preferences
 405          *
 406          * @param $namespaces Array
 407          * @return array
 408          */
 409         public static function namespacesAsText( $namespaces ) {
 410                 global $wgContLang;
 411
 412                 $formatted = array_map( array( $wgContLang, 'getFormattedNsText' ), $namespaces );
 413                 foreach ( $formatted as $key => $ns ) {
 414                         if ( empty( $ns ) ) {
 415                                 $formatted[$key] = wfMessage( 'blanknamespace' )->text();
 416                         }
 417                 }
 418                 return $formatted;
 419         }
 420
 421         /**
 422          * Return the help namespaces to be shown on Special:Search
 423          *
 424          * @return Array
 425          */
 426         public static function helpNamespaces() {
 427                 global $wgNamespacesToBeSearchedHelp;
 428
 429                 return array_keys( $wgNamespacesToBeSearchedHelp, true );
 430         }
 431
 432         /**
 433          * Return a 'cleaned up' search string
 434          *
 435          * @param $text String
 436          * @return String
 437          */
 438         function filter( $text ) {
 439                 $lc = $this->legalSearchChars();
 440                 return trim( preg_replace( "/[^{$lc}]/", " ", $text ) );
 441         }
 442
 443         /**
 444          * Load up the appropriate search engine class for the currently
 445          * active database backend, and return a configured instance.
 446          *
 447          * @param String $type Type of search backend, if not the default
 448          * @return SearchEngine
 449          */
 450         public static function create( $type = null ) {
 451                 global $wgSearchType;
 452                 $dbr = null;
 453
 454                 $alternatives = self::getSearchTypes();
 455
 456                 if ( $type && in_array( $type, $alternatives ) ) {
 457                         $class = $type;
 458                 } elseif ( $wgSearchType !== null ) {
 459                         $class = $wgSearchType;
 460                 } else {
 461                         $dbr = wfGetDB( DB_SLAVE );
 462                         $class = $dbr->getSearchEngine();
 463                 }
 464
 465                 $search = new $class( $dbr );
 466                 return $search;
 467         }
 468
 469         /**
 470          * Return the search engines we support. If only $wgSearchType
 471          * is set, it'll be an array of just that one item.
 472          *
 473          * @return array
 474          */
 475         public static function getSearchTypes() {
 476                 global $wgSearchType, $wgSearchTypeAlternatives;
 477
 478                 $alternatives = $wgSearchTypeAlternatives ?: array();
 479                 array_unshift( $alternatives, $wgSearchType );
 480
 481                 return $alternatives;
 482         }
 483
 484         /**
 485          * Create or update the search index record for the given page.
 486          * Title and text should be pre-processed.
 487          * STUB
 488          *
 489          * @param $id Integer
 490          * @param $title String
 491          * @param $text String
 492          */
 493         function update( $id, $title, $text ) {
 494                 // no-op
 495         }
 496
 497         /**
 498          * Update a search index record's title only.
 499          * Title should be pre-processed.
 500          * STUB
 501          *
 502          * @param $id Integer
 503          * @param $title String
 504          */
 505         function updateTitle( $id, $title ) {
 506                 // no-op
 507         }
 508
 509         /**
 510          * Delete an indexed page
 511          * Title should be pre-processed.
 512          * STUB
 513          *
 514          * @param Integer $id Page id that was deleted
 515          * @param String $title Title of page that was deleted
 516          */
 517         function delete( $id, $title ) {
 518                 // no-op
 519         }
 520
 521         /**
 522          * Get OpenSearch suggestion template
 523          *
 524          * @return String
 525          */
 526         public static function getOpenSearchTemplate() {
 527                 global $wgOpenSearchTemplate, $wgCanonicalServer;
 528                 if ( $wgOpenSearchTemplate ) {
 529                         return $wgOpenSearchTemplate;
 530                 } else {
 531                         $ns = implode( '|', SearchEngine::defaultNamespaces() );
 532                         if ( !$ns ) {
 533                                 $ns = "0";
 534                         }
 535                         return $wgCanonicalServer . wfScript( 'api' ) . '?action=opensearch&search={searchTerms}&namespace=' . $ns;
 536                 }
 537         }
 538
 539         /**
 540          * Get the raw text for updating the index from a content object
 541          * Nicer search backends could possibly do something cooler than
 542          * just returning raw text
 543          *
 544          * @todo This isn't ideal, we'd really like to have content-specific handling here
 545          * @param Title $t Title we're indexing
 546          * @param Content $c Content of the page to index
 547          * @return string
 548          */
 549         public function getTextFromContent( Title $t, Content $c = null ) {
 550                 return $c ? $c->getTextForSearchIndex() : '';
 551         }
 552
 553         /**
 554          * If an implementation of SearchEngine handles all of its own text processing
 555          * in getTextFromContent() and doesn't require SearchUpdate::updateText()'s
 556          * rather silly handling, it should return true here instead.
 557          *
 558          * @return bool
 559          */
 560         public function textAlreadyUpdatedForIndex() {
 561                 return false;
 562         }
 563 }
 564
 565 /**
 566  * @ingroup Search
 567  */
 568 class SearchResultSet {
 569         /**
 570          * Fetch an array of regular expression fragments for matching
 571          * the search terms as parsed by this engine in a text extract.
 572          * STUB
 573          *
 574          * @return Array
 575          */
 576         function termMatches() {
 577                 return array();
 578         }
 579
 580         function numRows() {
 581                 return 0;
 582         }
 583
 584         /**
 585          * Return true if results are included in this result set.
 586          * STUB
 587          *
 588          * @return Boolean
 589          */
 590         function hasResults() {
 591                 return false;
 592         }
 593
 594         /**
 595          * Some search modes return a total hit count for the query
 596          * in the entire article database. This may include pages
 597          * in namespaces that would not be matched on the given
 598          * settings.
 599          *
 600          * Return null if no total hits number is supported.
 601          *
 602          * @return Integer
 603          */
 604         function getTotalHits() {
 605                 return null;
 606         }
 607
 608         /**
 609          * Some search modes return a suggested alternate term if there are
 610          * no exact hits. Returns true if there is one on this set.
 611          *
 612          * @return Boolean
 613          */
 614         function hasSuggestion() {
 615                 return false;
 616         }
 617
 618         /**
 619          * @return String: suggested query, null if none
 620          */
 621         function getSuggestionQuery() {
 622                 return null;
 623         }
 624
 625         /**
 626          * @return String: HTML highlighted suggested query, '' if none
 627          */
 628         function getSuggestionSnippet() {
 629                 return '';
 630         }
 631
 632         /**
 633          * Return information about how and from where the results were fetched,
 634          * should be useful for diagnostics and debugging
 635          *
 636          * @return String
 637          */
 638         function getInfo() {
 639                 return null;
 640         }
 641
 642         /**
 643          * Return a result set of hits on other (multiple) wikis associated with this one
 644          *
 645          * @return SearchResultSet
 646          */
 647         function getInterwikiResults() {
 648                 return null;
 649         }
 650
 651         /**
 652          * Check if there are results on other wikis
 653          *
 654          * @return Boolean
 655          */
 656         function hasInterwikiResults() {
 657                 return $this->getInterwikiResults() != null;
 658         }
 659
 660         /**
 661          * Fetches next search result, or false.
 662          * STUB
 663          *
 664          * @return SearchResult
 665          */
 666         function next() {
 667                 return false;
 668         }
 669
 670         /**
 671          * Frees the result set, if applicable.
 672          */
 673         function free() {
 674                 // ...
 675         }
 676
 677         /**
 678          * Did the search contain search syntax?  If so, Special:Search won't offer
 679          * the user a link to a create a page named by the search string because the
 680          * name would contain the search syntax.
 681          */
 682         public function searchContainedSyntax() {
 683                 return false;
 684         }
 685 }
 686
 687 /**
 688  * This class is used for different SQL-based search engines shipped with MediaWiki
 689  */
 690 class SqlSearchResultSet extends SearchResultSet {
 691
 692         protected $mResultSet;
 693
 694         function __construct( $resultSet, $terms ) {
 695                 $this->mResultSet = $resultSet;
 696                 $this->mTerms = $terms;
 697         }
 698
 699         function termMatches() {
 700                 return $this->mTerms;
 701         }
 702
 703         function numRows() {
 704                 if ( $this->mResultSet === false ) {
 705                         return false;
 706                 }
 707
 708                 return $this->mResultSet->numRows();
 709         }
 710
 711         function next() {
 712                 if ( $this->mResultSet === false ) {
 713                         return false;
 714                 }
 715
 716                 $row = $this->mResultSet->fetchObject();
 717                 if ( $row === false ) {
 718                         return false;
 719                 }
 720
 721                 return SearchResult::newFromRow( $row );
 722         }
 723
 724         function free() {
 725                 if ( $this->mResultSet === false ) {
 726                         return false;
 727                 }
 728
 729                 $this->mResultSet->free();
 730         }
 731 }
 732
 733 /**
 734  * @ingroup Search
 735  */
 736 class SearchResultTooMany {
 737         # # Some search engines may bail out if too many matches are found
 738 }
 739
 740 /**
 741  * @todo FIXME: This class is horribly factored. It would probably be better to
 742  * have a useful base class to which you pass some standard information, then
 743  * let the fancy self-highlighters extend that.
 744  * @ingroup Search
 745  */
 746 class SearchResult {
 747
 748         /**
 749          * @var Revision
 750          */
 751         protected $mRevision = null;
 752
 753         /**
 754          * @var File
 755          */
 756         protected $mImage = null;
 757
 758         /**
 759          * @var Title
 760          */
 761         protected $mTitle;
 762
 763         /**
 764          * @var String
 765          */
 766         protected $mText;
 767
 768         /**
 769          * Return a new SearchResult and initializes it with a title.
 770          *
 771          * @param $title Title
 772          * @return SearchResult
 773          */
 774         public static function newFromTitle( $title ) {
 775                 $result = new self();
 776                 $result->initFromTitle( $title );
 777                 return $result;
 778         }
 779
 780         /**
 781          * Return a new SearchResult and initializes it with a row.
 782          *
 783          * @param $row object
 784          * @return SearchResult
 785          */
 786         public static function newFromRow( $row ) {
 787                 $result = new self();
 788                 $result->initFromRow( $row );
 789                 return $result;
 790         }
 791
 792         public function __construct( $row = null ) {
 793                 if ( !is_null( $row ) ) {
 794                         // Backwards compatibility with pre-1.17 callers
 795                         $this->initFromRow( $row );
 796                 }
 797         }
 798
 799         /**
 800          * Initialize from a database row. Makes a Title and passes that to
 801          * initFromTitle.
 802          *
 803          * @param $row object
 804          */
 805         protected function initFromRow( $row ) {
 806                 $this->initFromTitle( Title::makeTitle( $row->page_namespace, $row->page_title ) );
 807         }
 808
 809         /**
 810          * Initialize from a Title and if possible initializes a corresponding
 811          * Revision and File.
 812          *
 813          * @param $title Title
 814          */
 815         protected function initFromTitle( $title ) {
 816                 $this->mTitle = $title;
 817                 if ( !is_null( $this->mTitle ) ) {
 818                         $id = false;
 819                         wfRunHooks( 'SearchResultInitFromTitle', array( $title, &$id ) );
 820                         $this->mRevision = Revision::newFromTitle(
 821                                 $this->mTitle, $id, Revision::READ_NORMAL );
 822                         if ( $this->mTitle->getNamespace() === NS_FILE ) {
 823                                 $this->mImage = wfFindFile( $this->mTitle );
 824                         }
 825                 }
 826         }
 827
 828         /**
 829          * Check if this is result points to an invalid title
 830          *
 831          * @return Boolean
 832          */
 833         function isBrokenTitle() {
 834                 return is_null( $this->mTitle );
 835         }
 836
 837         /**
 838          * Check if target page is missing, happens when index is out of date
 839          *
 840          * @return Boolean
 841          */
 842         function isMissingRevision() {
 843                 return !$this->mRevision && !$this->mImage;
 844         }
 845
 846         /**
 847          * @return Title
 848          */
 849         function getTitle() {
 850                 return $this->mTitle;
 851         }
 852
 853         /**
 854          * Get the file for this page, if one exists
 855          * @return File|null
 856          */
 857         function getFile() {
 858                 return $this->mImage;
 859         }
 860
 861         /**
 862          * @return float|null if not supported
 863          */
 864         function getScore() {
 865                 return null;
 866         }
 867
 868         /**
 869          * Lazy initialization of article text from DB
 870          */
 871         protected function initText() {
 872                 if ( !isset( $this->mText ) ) {
 873                         if ( $this->mRevision != null ) {
 874                                 $this->mText = SearchEngine::create()
 875                                         ->getTextFromContent( $this->mTitle, $this->mRevision->getContent() );
 876                         } else { // TODO: can we fetch raw wikitext for commons images?
 877                                 $this->mText = '';
 878                         }
 879                 }
 880         }
 881
 882         /**
 883          * @param array $terms terms to highlight
 884          * @return String: highlighted text snippet, null (and not '') if not supported
 885          */
 886         function getTextSnippet( $terms ) {
 887                 global $wgAdvancedSearchHighlighting;
 888                 $this->initText();
 889
 890                 // TODO: make highliter take a content object. Make ContentHandler a factory for SearchHighliter.
 891                 list( $contextlines, $contextchars ) = SearchEngine::userHighlightPrefs();
 892                 $h = new SearchHighlighter();
 893                 if ( $wgAdvancedSearchHighlighting ) {
 894                         return $h->highlightText( $this->mText, $terms, $contextlines, $contextchars );
 895                 } else {
 896                         return $h->highlightSimple( $this->mText, $terms, $contextlines, $contextchars );
 897                 }
 898         }
 899
 900         /**
 901          * @return String: highlighted title, '' if not supported
 902          */
 903         function getTitleSnippet() {
 904                 return '';
 905         }
 906
 907         /**
 908          * @return String: highlighted redirect name (redirect to this page), '' if none or not supported
 909          */
 910         function getRedirectSnippet() {
 911                 return '';
 912         }
 913
 914         /**
 915          * @return Title object for the redirect to this page, null if none or not supported
 916          */
 917         function getRedirectTitle() {
 918                 return null;
 919         }
 920
 921         /**
 922          * @return string highlighted relevant section name, null if none or not supported
 923          */
 924         function getSectionSnippet() {
 925                 return '';
 926         }
 927
 928         /**
 929          * @return Title object (pagename+fragment) for the section, null if none or not supported
 930          */
 931         function getSectionTitle() {
 932                 return null;
 933         }
 934
 935         /**
 936          * @return String: timestamp
 937          */
 938         function getTimestamp() {
 939                 if ( $this->mRevision ) {
 940                         return $this->mRevision->getTimestamp();
 941                 } elseif ( $this->mImage ) {
 942                         return $this->mImage->getTimestamp();
 943                 }
 944                 return '';
 945         }
 946
 947         /**
 948          * @return Integer: number of words
 949          */
 950         function getWordCount() {
 951                 $this->initText();
 952                 return str_word_count( $this->mText );
 953         }
 954
 955         /**
 956          * @return Integer: size in bytes
 957          */
 958         function getByteSize() {
 959                 $this->initText();
 960                 return strlen( $this->mText );
 961         }
 962
 963         /**
 964          * @return Boolean if hit has related articles
 965          */
 966         function hasRelated() {
 967                 return false;
 968         }
 969
 970         /**
 971          * @return String: interwiki prefix of the title (return iw even if title is broken)
 972          */
 973         function getInterwikiPrefix() {
 974                 return '';
 975         }
 976
 977         /**
 978          * @return string interwiki namespace of the title (since we likely can't resolve it locally)
 979          */
 980         function getInterwikiNamespaceText() {
 981                 return '';
 982         }
 983
 984         /**
 985          * Did this match file contents (eg: PDF/DJVU)?
 986          */
 987         function isFileMatch() {
 988                 return false;
 989         }
 990 }
 991
 992 /**
 993  * A SearchResultSet wrapper for SearchEngine::getNearMatch
 994  */
 995 class SearchNearMatchResultSet extends SearchResultSet {
 996         private $fetched = false;
 997
 998         /**
 999          * @param $match mixed Title if matched, else null
1000          */
1001         public function __construct( $match ) {
1002                 $this->result = $match;
1003         }
1004
1005         public function hasResult() {
1006                 return (bool)$this->result;
1007         }
1008
1009         public function numRows() {
1010                 return $this->hasResults() ? 1 : 0;
1011         }
1012
1013         public function next() {
1014                 if ( $this->fetched || !$this->result ) {
1015                         return false;
1016                 }
1017                 $this->fetched = true;
1018                 return SearchResult::newFromTitle( $this->result );
1019         }
1020 }
1021
1022 /**
1023  * Highlight bits of wikitext
1024  *
1025  * @ingroup Search
1026  */
1027 class SearchHighlighter {
1028         var $mCleanWikitext = true;
1029
1030         function __construct( $cleanupWikitext = true ) {
1031                 $this->mCleanWikitext = $cleanupWikitext;
1032         }
1033
1034         /**
1035          * Default implementation of wikitext highlighting
1036          *
1037          * @param $text String
1038          * @param array $terms terms to highlight (unescaped)
1039          * @param $contextlines Integer
1040          * @param $contextchars Integer
1041          * @return String
1042          */
1043         public function highlightText( $text, $terms, $contextlines, $contextchars ) {
1044                 global $wgContLang;
1045                 global $wgSearchHighlightBoundaries;
1046                 $fname = __METHOD__;
1047
1048                 if ( $text == '' ) {
1049                         return '';
1050                 }
1051
1052                 // spli text into text + templates/links/tables
1053                 $spat = "/(\\{\\{)|(\\[\\[[^\\]:]+:)|(\n\\{\\|)";
1054                 // first capture group is for detecting nested templates/links/tables/references
1055                 $endPatterns = array(
1056                         1 => '/(\{\{)|(\}\})/', // template
1057                         2 => '/(\[\[)|(\]\])/', // image
1058                         3 => "/(\n\\{\\|)|(\n\\|\\})/" ); // table
1059
1060                 // @todo FIXME: This should prolly be a hook or something
1061                 if ( function_exists( 'wfCite' ) ) {
1062                         $spat .= '|(<ref>)'; // references via cite extension
1063                         $endPatterns[4] = '/(<ref>)|(<\/ref>)/';
1064                 }
1065                 $spat .= '/';
1066                 $textExt = array(); // text extracts
1067                 $otherExt = array(); // other extracts
1068                 wfProfileIn( "$fname-split" );
1069                 $start = 0;
1070                 $textLen = strlen( $text );
1071                 $count = 0; // sequence number to maintain ordering
1072                 while ( $start < $textLen ) {
1073                         // find start of template/image/table
1074                         if ( preg_match( $spat, $text, $matches, PREG_OFFSET_CAPTURE, $start ) ) {
1075                                 $epat = '';
1076                                 foreach ( $matches as $key => $val ) {
1077                                         if ( $key > 0 && $val[1] != - 1 ) {
1078                                                 if ( $key == 2 ) {
1079                                                         // see if this is an image link
1080                                                         $ns = substr( $val[0], 2, - 1 );
1081                                                         if ( $wgContLang->getNsIndex( $ns ) != NS_FILE ) {
1082                                                                 break;
1083                                                         }
1084
1085                                                 }
1086                                                 $epat = $endPatterns[$key];
1087                                                 $this->splitAndAdd( $textExt, $count, substr( $text, $start, $val[1] - $start ) );
1088                                                 $start = $val[1];
1089                                                 break;
1090                                         }
1091                                 }
1092                                 if ( $epat ) {
1093                                         // find end (and detect any nested elements)
1094                                         $level = 0;
1095                                         $offset = $start + 1;
1096                                         $found = false;
1097                                         while ( preg_match( $epat, $text, $endMatches, PREG_OFFSET_CAPTURE, $offset ) ) {
1098                                                 if ( array_key_exists( 2, $endMatches ) ) {
1099                                                         // found end
1100                                                         if ( $level == 0 ) {
1101                                                                 $len = strlen( $endMatches[2][0] );
1102                                                                 $off = $endMatches[2][1];
1103                                                                 $this->splitAndAdd( $otherExt, $count,
1104                                                                         substr( $text, $start, $off + $len - $start ) );
1105                                                                 $start = $off + $len;
1106                                                                 $found = true;
1107                                                                 break;
1108                                                         } else {
1109                                                                 // end of nested element
1110                                                                 $level -= 1;
1111                                                         }
1112                                                 } else {
1113                                                         // nested
1114                                                         $level += 1;
1115                                                 }
1116                                                 $offset = $endMatches[0][1] + strlen( $endMatches[0][0] );
1117                                         }
1118                                         if ( ! $found ) {
1119                                                 // couldn't find appropriate closing tag, skip
1120                                                 $this->splitAndAdd( $textExt, $count, substr( $text, $start, strlen( $matches[0][0] ) ) );
1121                                                 $start += strlen( $matches[0][0] );
1122                                         }
1123                                         continue;
1124                                 }
1125                         }
1126                         // else: add as text extract
1127                         $this->splitAndAdd( $textExt, $count, substr( $text, $start ) );
1128                         break;
1129                 }
1130
1131                 $all = $textExt + $otherExt; // these have disjunct key sets
1132
1133                 wfProfileOut( "$fname-split" );
1134
1135                 // prepare regexps
1136                 foreach ( $terms as $index => $term ) {
1137                         // manually do upper/lowercase stuff for utf-8 since PHP won't do it
1138                         if ( preg_match( '/[\x80-\xff]/', $term ) ) {
1139                                 $terms[$index] = preg_replace_callback( '/./us', array( $this, 'caseCallback' ), $terms[$index] );
1140                         } else {
1141                                 $terms[$index] = $term;
1142                         }
1143                 }
1144                 $anyterm = implode( '|', $terms );
1145                 $phrase = implode( "$wgSearchHighlightBoundaries+", $terms );
1146
1147                 // @todo FIXME: A hack to scale contextchars, a correct solution
1148                 // would be to have contextchars actually be char and not byte
1149                 // length, and do proper utf-8 substrings and lengths everywhere,
1150                 // but PHP is making that very hard and unclean to implement :(
1151                 $scale = strlen( $anyterm ) / mb_strlen( $anyterm );
1152                 $contextchars = intval( $contextchars * $scale );
1153
1154                 $patPre = "(^|$wgSearchHighlightBoundaries)";
1155                 $patPost = "($wgSearchHighlightBoundaries|$)";
1156
1157                 $pat1 = "/(" . $phrase . ")/ui";
1158                 $pat2 = "/$patPre(" . $anyterm . ")$patPost/ui";
1159
1160                 wfProfileIn( "$fname-extract" );
1161
1162                 $left = $contextlines;
1163
1164                 $snippets = array();
1165                 $offsets = array();
1166
1167                 // show beginning only if it contains all words
1168                 $first = 0;
1169                 $firstText = '';
1170                 foreach ( $textExt as $index => $line ) {
1171                         if ( strlen( $line ) > 0 && $line[0] != ';' && $line[0] != ':' ) {
1172                                 $firstText = $this->extract( $line, 0, $contextchars * $contextlines );
1173                                 $first = $index;
1174                                 break;
1175                         }
1176                 }
1177                 if ( $firstText ) {
1178                         $succ = true;
1179                         // check if first text contains all terms
1180                         foreach ( $terms as $term ) {
1181                                 if ( ! preg_match( "/$patPre" . $term . "$patPost/ui", $firstText ) ) {
1182                                         $succ = false;
1183                                         break;
1184                                 }
1185                         }
1186                         if ( $succ ) {
1187                                 $snippets[$first] = $firstText;
1188                                 $offsets[$first] = 0;
1189                         }
1190                 }
1191                 if ( ! $snippets ) {
1192                         // match whole query on text
1193                         $this->process( $pat1, $textExt, $left, $contextchars, $snippets, $offsets );
1194                         // match whole query on templates/tables/images
1195                         $this->process( $pat1, $otherExt, $left, $contextchars, $snippets, $offsets );
1196                         // match any words on text
1197                         $this->process( $pat2, $textExt, $left, $contextchars, $snippets, $offsets );
1198                         // match any words on templates/tables/images
1199                         $this->process( $pat2, $otherExt, $left, $contextchars, $snippets, $offsets );
1200
1201                         ksort( $snippets );
1202                 }
1203
1204                 // add extra chars to each snippet to make snippets constant size
1205                 $extended = array();
1206                 if ( count( $snippets ) == 0 ) {
1207                         // couldn't find the target words, just show beginning of article
1208                         if ( array_key_exists( $first, $all ) ) {
1209                                 $targetchars = $contextchars * $contextlines;
1210                                 $snippets[$first] = '';
1211                                 $offsets[$first] = 0;
1212                         }
1213                 } else {
1214                         // if begin of the article contains the whole phrase, show only that !!
1215                         if ( array_key_exists( $first, $snippets ) && preg_match( $pat1, $snippets[$first] )
1216                                 && $offsets[$first] < $contextchars * 2 ) {
1217                                 $snippets = array( $first => $snippets[$first] );
1218                         }
1219
1220                         // calc by how much to extend existing snippets
1221                         $targetchars = intval( ( $contextchars * $contextlines ) / count ( $snippets ) );
1222                 }
1223
1224                 foreach ( $snippets as $index => $line ) {
1225                         $extended[$index] = $line;
1226                         $len = strlen( $line );
1227                         if ( $len < $targetchars - 20 ) {
1228                                 // complete this line
1229                                 if ( $len < strlen( $all[$index] ) ) {
1230                                         $extended[$index] = $this->extract( $all[$index], $offsets[$index], $offsets[$index] + $targetchars, $offsets[$index] );
1231                                         $len = strlen( $extended[$index] );
1232                                 }
1233
1234                                 // add more lines
1235                                 $add = $index + 1;
1236                                 while ( $len < $targetchars - 20
1237                                                 && array_key_exists( $add, $all )
1238                                                 && !array_key_exists( $add, $snippets ) ) {
1239                                         $offsets[$add] = 0;
1240                                         $tt = "\n" . $this->extract( $all[$add], 0, $targetchars - $len, $offsets[$add] );
1241                                         $extended[$add] = $tt;
1242                                         $len += strlen( $tt );
1243                                         $add++;
1244                                 }
1245                         }
1246                 }
1247
1248                 // $snippets = array_map( 'htmlspecialchars', $extended );
1249                 $snippets = $extended;
1250                 $last = - 1;
1251                 $extract = '';
1252                 foreach ( $snippets as $index => $line ) {
1253                         if ( $last == - 1 ) {
1254                                 $extract .= $line; // first line
1255                         } elseif ( $last + 1 == $index && $offsets[$last] + strlen( $snippets[$last] ) >= strlen( $all[$last] ) ) {
1256                                 $extract .= " " . $line; // continous lines
1257                         } else {
1258                                 $extract .= '<b> ... </b>' . $line;
1259                         }
1260
1261                         $last = $index;
1262                 }
1263                 if ( $extract ) {
1264                         $extract .= '<b> ... </b>';
1265                 }
1266
1267                 $processed = array();
1268                 foreach ( $terms as $term ) {
1269                         if ( ! isset( $processed[$term] ) ) {
1270                                 $pat3 = "/$patPre(" . $term . ")$patPost/ui"; // highlight word
1271                                 $extract = preg_replace( $pat3,
1272                                         "\\1<span class='searchmatch'>\\2</span>\\3", $extract );
1273                                 $processed[$term] = true;
1274                         }
1275                 }
1276
1277                 wfProfileOut( "$fname-extract" );
1278
1279                 return $extract;
1280         }
1281
1282         /**
1283          * Split text into lines and add it to extracts array
1284          *
1285          * @param array $extracts index -> $line
1286          * @param $count Integer
1287          * @param $text String
1288          */
1289         function splitAndAdd( &$extracts, &$count, $text ) {
1290                 $split = explode( "\n", $this->mCleanWikitext ? $this->removeWiki( $text ) : $text );
1291                 foreach ( $split as $line ) {
1292                         $tt = trim( $line );
1293                         if ( $tt ) {
1294                                 $extracts[$count++] = $tt;
1295                         }
1296                 }
1297         }
1298
1299         /**
1300          * Do manual case conversion for non-ascii chars
1301          *
1302          * @param $matches Array
1303          * @return string
1304          */
1305         function caseCallback( $matches ) {
1306                 global $wgContLang;
1307                 if ( strlen( $matches[0] ) > 1 ) {
1308                         return '[' . $wgContLang->lc( $matches[0] ) . $wgContLang->uc( $matches[0] ) . ']';
1309                 } else {
1310                         return $matches[0];
1311                 }
1312         }
1313
1314         /**
1315          * Extract part of the text from start to end, but by
1316          * not chopping up words
1317          * @param $text String
1318          * @param $start Integer
1319          * @param $end Integer
1320          * @param $posStart Integer: (out) actual start position
1321          * @param $posEnd Integer: (out) actual end position
1322          * @return String
1323          */
1324         function extract( $text, $start, $end, &$posStart = null, &$posEnd = null ) {
1325                 if ( $start != 0 ) {
1326                         $start = $this->position( $text, $start, 1 );
1327                 }
1328                 if ( $end >= strlen( $text ) ) {
1329                         $end = strlen( $text );
1330                 } else {
1331                         $end = $this->position( $text, $end );
1332                 }
1333
1334                 if ( !is_null( $posStart ) ) {
1335                         $posStart = $start;
1336                 }
1337                 if ( !is_null( $posEnd ) ) {
1338                         $posEnd = $end;
1339                 }
1340
1341                 if ( $end > $start ) {
1342                         return substr( $text, $start, $end - $start );
1343                 } else {
1344                         return '';
1345                 }
1346         }
1347
1348         /**
1349          * Find a nonletter near a point (index) in the text
1350          *
1351          * @param $text String
1352          * @param $point Integer
1353          * @param $offset Integer: offset to found index
1354          * @return Integer: nearest nonletter index, or beginning of utf8 char if none
1355          */
1356         function position( $text, $point, $offset = 0 ) {
1357                 $tolerance = 10;
1358                 $s = max( 0, $point - $tolerance );
1359                 $l = min( strlen( $text ), $point + $tolerance ) - $s;
1360                 $m = array();
1361                 if ( preg_match( '/[ ,.!?~!@#$%^&*\(\)+=\-\\\|\[\]"\'<>]/', substr( $text, $s, $l ), $m, PREG_OFFSET_CAPTURE ) ) {
1362                         return $m[0][1] + $s + $offset;
1363                 } else {
1364                         // check if point is on a valid first UTF8 char
1365                         $char = ord( $text[$point] );
1366                         while ( $char >= 0x80 && $char < 0xc0 ) {
1367                                 // skip trailing bytes
1368                                 $point++;
1369                                 if ( $point >= strlen( $text ) ) {
1370                                         return strlen( $text );
1371                                 }
1372                                 $char = ord( $text[$point] );
1373                         }
1374                         return $point;
1375
1376                 }
1377         }
1378
1379         /**
1380          * Search extracts for a pattern, and return snippets
1381          *
1382          * @param string $pattern regexp for matching lines
1383          * @param array $extracts extracts to search
1384          * @param $linesleft Integer: number of extracts to make
1385          * @param $contextchars Integer: length of snippet
1386          * @param array $out map for highlighted snippets
1387          * @param array $offsets map of starting points of snippets
1388          * @protected
1389          */
1390         function process( $pattern, $extracts, &$linesleft, &$contextchars, &$out, &$offsets ) {
1391                 if ( $linesleft == 0 ) {
1392                         return; // nothing to do
1393                 }
1394                 foreach ( $extracts as $index => $line ) {
1395                         if ( array_key_exists( $index, $out ) ) {
1396                                 continue; // this line already highlighted
1397                         }
1398
1399                         $m = array();
1400                         if ( !preg_match( $pattern, $line, $m, PREG_OFFSET_CAPTURE ) ) {
1401                                 continue;
1402                         }
1403
1404                         $offset = $m[0][1];
1405                         $len = strlen( $m[0][0] );
1406                         if ( $offset + $len < $contextchars ) {
1407                                 $begin = 0;
1408                         } elseif ( $len > $contextchars ) {
1409                                 $begin = $offset;
1410                         } else {
1411                                 $begin = $offset + intval( ( $len - $contextchars ) / 2 );
1412                         }
1413
1414                         $end = $begin + $contextchars;
1415
1416                         $posBegin = $begin;
1417                         // basic snippet from this line
1418                         $out[$index] = $this->extract( $line, $begin, $end, $posBegin );
1419                         $offsets[$index] = $posBegin;
1420                         $linesleft--;
1421                         if ( $linesleft == 0 ) {
1422                                 return;
1423                         }
1424                 }
1425         }
1426
1427         /**
1428          * Basic wikitext removal
1429          * @protected
1430          * @return mixed
1431          */
1432         function removeWiki( $text ) {
1433                 $fname = __METHOD__;
1434                 wfProfileIn( $fname );
1435
1436                 // $text = preg_replace( "/'{2,5}/", "", $text );
1437                 // $text = preg_replace( "/\[[a-z]+:\/\/[^ ]+ ([^]]+)\]/", "\\2", $text );
1438                 // $text = preg_replace( "/\[\[([^]|]+)\]\]/", "\\1", $text );
1439                 // $text = preg_replace( "/\[\[([^]]+\|)?([^|]]+)\]\]/", "\\2", $text );
1440                 // $text = preg_replace( "/\\{\\|(.*?)\\|\\}/", "", $text );
1441                 // $text = preg_replace( "/\\[\\[[A-Za-z_-]+:([^|]+?)\\]\\]/", "", $text );
1442                 $text = preg_replace( "/\\{\\{([^|]+?)\\}\\}/", "", $text );
1443                 $text = preg_replace( "/\\{\\{([^|]+\\|)(.*?)\\}\\}/", "\\2", $text );
1444                 $text = preg_replace( "/\\[\\[([^|]+?)\\]\\]/", "\\1", $text );
1445                 $text = preg_replace_callback( "/\\[\\[([^|]+\\|)(.*?)\\]\\]/", array( $this, 'linkReplace' ), $text );
1446                 // $text = preg_replace("/\\[\\[([^|]+\\|)(.*?)\\]\\]/", "\\2", $text);
1447                 $text = preg_replace( "/<\/?[^>]+>/", "", $text );
1448                 $text = preg_replace( "/'''''/", "", $text );
1449                 $text = preg_replace( "/('''|<\/?[iIuUbB]>)/", "", $text );
1450                 $text = preg_replace( "/''/", "", $text );
1451
1452                 wfProfileOut( $fname );
1453                 return $text;
1454         }
1455
1456         /**
1457          * callback to replace [[target|caption]] kind of links, if
1458          * the target is category or image, leave it
1459          *
1460          * @param $matches Array
1461          */
1462         function linkReplace( $matches ) {
1463                 $colon = strpos( $matches[1], ':' );
1464                 if ( $colon === false ) {
1465                         return $matches[2]; // replace with caption
1466                 }
1467                 global $wgContLang;
1468                 $ns = substr( $matches[1], 0, $colon );
1469                 $index = $wgContLang->getNsIndex( $ns );
1470                 if ( $index !== false && ( $index == NS_FILE || $index == NS_CATEGORY ) ) {
1471                         return $matches[0]; // return the whole thing
1472                 } else {
1473                         return $matches[2];
1474                 }
1475         }
1476
1477         /**
1478          * Simple & fast snippet extraction, but gives completely unrelevant
1479          * snippets
1480          *
1481          * @param $text String
1482          * @param $terms Array
1483          * @param $contextlines Integer
1484          * @param $contextchars Integer
1485          * @return String
1486          */
1487         public function highlightSimple( $text, $terms, $contextlines, $contextchars ) {
1488                 global $wgContLang;
1489                 $fname = __METHOD__;
1490
1491                 $lines = explode( "\n", $text );
1492
1493                 $terms = implode( '|', $terms );
1494                 $max = intval( $contextchars ) + 1;
1495                 $pat1 = "/(.*)($terms)(.{0,$max})/i";
1496
1497                 $lineno = 0;
1498
1499                 $extract = "";
1500                 wfProfileIn( "$fname-extract" );
1501                 foreach ( $lines as $line ) {
1502                         if ( 0 == $contextlines ) {
1503                                 break;
1504                         }
1505                         ++$lineno;
1506                         $m = array();
1507                         if ( ! preg_match( $pat1, $line, $m ) ) {
1508                                 continue;
1509                         }
1510                         --$contextlines;
1511                         // truncate function changes ... to relevant i18n message.
1512                         $pre = $wgContLang->truncate( $m[1], - $contextchars, '...', false );
1513
1514                         if ( count( $m ) < 3 ) {
1515                                 $post = '';
1516                         } else {
1517                                 $post = $wgContLang->truncate( $m[3], $contextchars, '...', false );
1518                         }
1519
1520                         $found = $m[2];
1521
1522                         $line = htmlspecialchars( $pre . $found . $post );
1523                         $pat2 = '/(' . $terms . ")/i";
1524                         $line = preg_replace( $pat2, "<span class='searchmatch'>\\1</span>", $line );
1525
1526                         $extract .= "${line}\n";
1527                 }
1528                 wfProfileOut( "$fname-extract" );
1529
1530                 return $extract;
1531         }
1532
1533 }
1534
1535 /**
1536  * Dummy class to be used when non-supported Database engine is present.
1537  * @todo FIXME: Dummy class should probably try something at least mildly useful,
1538  * such as a LIKE search through titles.
1539  * @ingroup Search
1540  */
1541 class SearchEngineDummy extends SearchEngine {
1542         // no-op
1543 }