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