Uh, also I shouldn't introduce syntax errors while fixing regressions.
[lhc/web/wiklou.git] / includes / SearchEngine.php
index 4e01ee7..916e1fd 100644 (file)
 <?php
-# See search.doc
-
+/**
+ * @defgroup Search Search
+ *
+ * @file
+ * @ingroup Search
+ */
+
+/**
+ * Contain a class for special pages
+ * @ingroup Search
+ */
 class SearchEngine {
-       /* private */ var $mRawtext, $mUsertext, $mSearchterms;
-       /* private */ var $mTitlecond, $mTextcond;
-
-       var $doSearchRedirects = true;
-       var $addtoquery = array();
-       var $namespacesToSearch = array();
-       var $alternateTitle;
-       var $all_titles = false;
-
-       function SearchEngine( $text )
-       {
-               # We display the query, so let's strip it for safety
-               #
-               global $wgDBmysql4;
-               $lc = SearchEngine::legalSearchChars() . "()";
-               if( $wgDBmysql4 ) $lc .= "\"~<>*+-";
-               $this->mRawtext = $text;
-               $this->mUsertext = trim( preg_replace( "/[^{$lc}]/", " ", $text ) );
-               $this->mSearchterms = array();
-               $this->mStrictMatching = true; # Google-style, add '+' on all terms
-       }
-
-       function queryNamespaces()
-       {
-               $namespaces = implode( ",", $this->namespacesToSearch );
-               if ($namespaces == "") {
-                       $namespaces = "0";
-               }
-               return "AND cur_namespace IN (" . $namespaces . ")";
+       var $limit = 10;
+       var $offset = 0;
+       var $searchTerms = array();
+       var $namespaces = array( NS_MAIN );
+       var $showRedirects = false;
+
+       /**
+        * Perform a full text search query and return a result set.
+        * If title searches are not supported or disabled, return null.
+        *
+        * @param string $term - Raw search term
+        * @return SearchResultSet
+        * @access public
+        * @abstract
+        */
+       function searchText( $term ) {
+               return null;
        }
 
-       function searchRedirects()
-       {
-               if ( $this->doSearchRedirects ) {
-                       return "";
-               } else {
-                       return "AND cur_is_redirect=0 ";
-               }
+       /**
+        * Perform a title-only search query and return a result set.
+        * If title searches are not supported or disabled, return null.
+        *
+        * @param string $term - Raw search term
+        * @return SearchResultSet
+        * @access public
+        * @abstract
+        */
+       function searchTitle( $term ) {
+               return null;
        }
-
-       /* private */ function initNamespaceCheckbox( $i )
-       {
-               global $wgUser, $wgNamespacesToBeSearchedDefault;
-               
-               if ($wgUser->getID()) {
-                       // User is logged in so we retrieve his default namespaces
-                       return $wgUser->getOption( "searchNs".$i );
-               } else {
-                       // User is not logged in so we give him the global default namespaces
-                       return !empty($wgNamespacesToBeSearchedDefault[ $i ]);
+       
+       /**
+        * If an exact title match can be find, or a very slightly close match,
+        * return the title. If no match, returns NULL.
+        *
+        * @param string $term
+        * @return Title
+        */
+       public static function getNearMatch( $searchterm ) {
+               global $wgContLang;
+
+               $allSearchTerms = array($searchterm);
+
+               if($wgContLang->hasVariants()){
+                       $allSearchTerms = array_merge($allSearchTerms,$wgContLang->convertLinkToAllVariants($searchterm));
                }
-       }
 
-       # Display the "power search" footer. Does not actually perform the search, 
-       # that is done by showResults()
-       function powersearch()
-       {
-               global $wgUser, $wgOut, $wgLang, $wgTitle, $wgRequest;
-               $sk =& $wgUser->getSkin();
-               
-               $search                 = $wgRequest->getText( 'search' );
-               $searchx                = $wgRequest->getVal( 'searchx' );
-               $listredirs             = $wgRequest->getVal( 'redirs' );
-               
-               $ret = wfMsg("powersearchtext"); # Text to be returned
-               $tempText = ""; # Temporary text, for substitution into $ret    
+               foreach($allSearchTerms as $term){
 
-               if( isset( $_REQUEST["searchx"] ) ) {
-                       $this->addtoquery["searchx"] = "1";
-               }
-               
-               # Do namespace checkboxes
-               $namespaces = $wgLang->getNamespaces();
-               foreach ( $namespaces as $i => $namespace ) {
-                       # Skip virtual namespaces
-                       if ( $i < 0 ) {
-                               continue;
+                       # Exact match? No need to look further.
+                       $title = Title::newFromText( $term );
+                       if (is_null($title))
+                               return NULL;
+
+                       if ( $title->getNamespace() == NS_SPECIAL || $title->isExternal() 
+                            || $title->exists() ) {
+                               return $title;
                        }
 
-                       $formVar = "ns$i";
+                       # Now try all lower case (i.e. first letter capitalized)
+                       #
+                       $title = Title::newFromText( $wgContLang->lc( $term ) );
+                       if ( $title && $title->exists() ) {
+                               return $title;
+                       }
 
-                       # Initialise checkboxValues, either from defaults or from 
-                       # a previous invocation
-                       if ( !isset( $searchx ) ) {
-                               $checkboxValue = $this->initNamespaceCheckbox( $i );
-                       } else {
-                               $checkboxValue = $wgRequest->getVal( $formVar );
+                       # Now try capitalized string
+                       #
+                       $title = Title::newFromText( $wgContLang->ucwords( $term ) );
+                       if ( $title && $title->exists() ) {
+                               return $title;
                        }
 
-                       $checked = "";
-                       if ( $checkboxValue == 1 ) {
-                               $checked = " checked='checked'";
-                               $this->addtoquery["ns{$i}"] = 1;
-                               array_push( $this->namespacesToSearch, $i );
+                       # Now try all upper case
+                       #
+                       $title = Title::newFromText( $wgContLang->uc( $term ) );
+                       if ( $title && $title->exists() ) {
+                               return $title;
                        }
-                       $name = str_replace( "_", " ", $namespaces[$i] );
-                       if ( "" == $name ) { 
-                               $name = wfMsg( "blanknamespace" ); 
+
+                       # Now try Word-Caps-Breaking-At-Word-Breaks, for hyphenated names etc
+                       $title = Title::newFromText( $wgContLang->ucwordbreaks($term) );
+                       if ( $title && $title->exists() ) {
+                               return $title;
                        }
 
-                       if ( $tempText !== "" ) { 
-                               $tempText .= " "; 
+                       // Give hooks a chance at better match variants
+                       $title = null;
+                       if( !wfRunHooks( 'SearchGetNearMatch', array( $term, &$title ) ) ) {
+                               return $title;
                        }
-                       $tempText .= "<input type='checkbox' value=\"1\" name=\"" .
-                         "ns{$i}\"{$checked} />{$name}\n";
                }
-               $ret = str_replace ( "$1", $tempText, $ret );
 
-               # List redirects checkbox
+               $title = Title::newFromText( $searchterm );
 
-               $checked = "";
-               if ( $listredirs == 1 ) {
-                       $this->addtoquery["redirs"] = 1;
-                       $checked = " checked='checked'";
+               # Entering an IP address goes to the contributions page
+               if ( ( $title->getNamespace() == NS_USER && User::isIP($title->getText() ) )
+                       || User::isIP( trim( $searchterm ) ) ) {
+                       return SpecialPage::getTitleFor( 'Contributions', $title->getDBkey() );
                }
-               $tempText = "<input type='checkbox' value='1' name=\"redirs\"{$checked} />\n";
-               $ret = str_replace( "$2", $tempText, $ret );
-
-               # Search field
-
-               $tempText = "<input type='text' name=\"search\" value=\"" .
-                       htmlspecialchars( $search ) ."\" width='80' />\n";
-        $ret = str_replace( "$3", $tempText, $ret );
 
-               # Searchx button
 
-               $tempText = "<input type='submit' name=\"searchx\" value=\"" .
-                 wfMsg("powersearch") . "\" />\n";
-               $ret = str_replace( "$9", $tempText, $ret );
-
-               $action = $sk->escapeSearchLink();
-               $ret = "<br /><br />\n<form id=\"powersearch\" method=\"get\" " .
-                 "action=\"$action\">\n{$ret}\n</form>\n";
+               # Entering a user goes to the user page whether it's there or not
+               if ( $title->getNamespace() == NS_USER ) {
+                       return $title;
+               }
 
-               if ( isset ( $searchx ) ) {
-                       if ( ! $listredirs ) { 
-                               $this->doSearchRedirects = false; 
+               # Go to images that exist even if there's no local page.
+               # There may have been a funny upload, or it may be on a shared
+               # file repository such as Wikimedia Commons.
+               if( $title->getNamespace() == NS_IMAGE ) {
+                       $image = wfFindFile( $title );
+                       if( $image ) {
+                               return $title;
                        }
                }
-               return $ret;
-       }
 
-       function setupPage() {
-               global $wgOut;
-               $wgOut->setPageTitle( wfMsg( "searchresults" ) );
-               $q = wfMsg( "searchquery", htmlspecialchars( $this->mRawtext ) );
-               $wgOut->setSubtitle( $q );
-               $wgOut->setArticleRelated( false );
-               $wgOut->setRobotpolicy( "noindex,nofollow" );
-       }
+               # MediaWiki namespace? Page may be "implied" if not customized.
+               # Just return it, with caps forced as the message system likes it.
+               if( $title->getNamespace() == NS_MEDIAWIKI ) {
+                       return Title::makeTitle( NS_MEDIAWIKI, $wgContLang->ucfirst( $title->getText() ) );
+               }
 
-       # Perform the search and construct the results page
-       function showResults()
-       {
-               global $wgUser, $wgTitle, $wgOut, $wgLang, $wgRequest;
-               global $wgDisableTextSearch, $wgInputEncoding;
-               $fname = "SearchEngine::showResults";
+               # Quoted term? Try without the quotes...
+               $matches = array();
+               if( preg_match( '/^"([^"]+)"$/', $searchterm, $matches ) ) {
+                       return SearchEngine::getNearMatch( $matches[1] );
+               }
 
-               $search = $wgRequest->getText( 'search' );
+               return NULL;
+       }
 
-               $powersearch = $this->powersearch(); /* Need side-effects here? */
+       public static function legalSearchChars() {
+               return "A-Za-z_'0-9\\x80-\\xFF\\-";
+       }
 
-               $this->setupPage();
+       /**
+        * Set the maximum number of results to return
+        * and how many to skip before returning the first.
+        *
+        * @param int $limit
+        * @param int $offset
+        * @access public
+        */
+       function setLimitOffset( $limit, $offset = 0 ) {
+               $this->limit = intval( $limit );
+               $this->offset = intval( $offset );
+       }
 
-               $sk = $wgUser->getSkin();
-               $header = wfMsg( "searchresulttext", $sk->makeKnownLink(
-                                       wfMsg( "searchhelppage" ), wfMsg( "searchingwikipedia" ) ) );
-               $wgOut->addHTML( $header );
+       /**
+        * Set which namespaces the search should include.
+        * Give an array of namespace index numbers.
+        *
+        * @param array $namespaces
+        * @access public
+        */
+       function setNamespaces( $namespaces ) {
+               $this->namespaces = $namespaces;
+       }
 
-               $dbr =& wfGetDB( DB_SLAVE );
-               $this->parseQuery( $dbr );
-               if ( "" == $this->mTitlecond || "" == $this->mTextcond ) {
-                       $wgOut->addHTML( "<h2>" . wfMsg( "badquery" ) . "</h2>\n" .
-                         "<p>" . wfMsg( "badquerytext" ) . "</p>\n" );
-                       return;
+       /**
+        * Parse some common prefixes: all (search everything)
+        * or namespace names
+        *
+        * @param string $query
+        */
+       function replacePrefixes( $query ){
+               global $wgContLang;
+
+               if( strpos($query,':') === false )
+                       return $query; // nothing to do
+
+               $parsed = $query;
+               $allkeyword = wfMsgForContent('searchall').":";
+               if( strncmp($query, $allkeyword, strlen($allkeyword)) == 0 ){
+                       $this->namespaces = null;
+                       $parsed = substr($query,strlen($allkeyword));
+               } else if( strpos($query,':') !== false ) {
+                       $prefix = substr($query,0,strpos($query,':'));
+                       $index = $wgContLang->getNsIndex($prefix);
+                       if($index !== false){
+                               $this->namespaces = array($index);
+                               $parsed = substr($query,strlen($prefix)+1);
+                       }
                }
-               list( $limit, $offset ) = wfCheckLimits( 20, "searchlimit" );
+               if(trim($parsed) == '')
+                       return $query; // prefix was the whole query
 
-               $searchnamespaces = $this->queryNamespaces();
-               $redircond = $this->searchRedirects();
-               $searchindex = $dbr->tableName( 'searchindex' );
-               $cur = $dbr->tableName( 'cur' );
-               
-               if ( $wgDisableTextSearch ) {
-                       $wgOut->addHTML( wfMsg( "searchdisabled" ) );
-                       $wgOut->addHTML( wfMsg( "googlesearch", htmlspecialchars( $search ), $GLOBALS['wgInputEncoding'] ) );
-               } else {
-                       $sql = "SELECT cur_id,cur_namespace,cur_title," .
-                         "cur_text FROM $cur,$searchindex " .
-                         "WHERE cur_id=si_page AND {$this->mTitlecond} " .
-                         "{$searchnamespaces} {$redircond}" .
-                         "LIMIT {$offset}, {$limit}";
-                       $res1 = $dbr->query( $sql, $fname );
-                       $num = $dbr->numRows($res1);
-
-                       $sk = $wgUser->getSkin();
-                       $text = "";
-
-                       $this->parseQuery( $dbr );
-                       if ( "" == $this->mTitlecond || "" == $this->mTextcond ) {
-                               $wgOut->addHTML( "<h2>" . wfMsg( "badquery" ) . "</h2>\n" .
-                                 "<p>" . wfMsg( "badquerytext" ) . "</p>\n" );
-                               return;
-                       }
-                       list( $limit, $offset ) = wfCheckLimits( 20, "searchlimit" );
-       
-                       $searchnamespaces = $this->queryNamespaces();
-                       $redircond = $this->searchRedirects();
-       
-                       $sql = "SELECT cur_id,cur_namespace,cur_title," .
-                         "cur_text FROM $cur,$searchindex " .
-                         "WHERE cur_id=si_page AND {$this->mTitlecond} " .
-                         "{$searchnamespaces} {$redircond}" .
-                         "LIMIT {$offset}, {$limit}";
-                       $res1 = $dbr->query( $sql, $fname );
-                       $num = $dbr->numRows($res1);
-       
-                       $sql = "SELECT cur_id,cur_namespace,cur_title," .
-                         "cur_text FROM $cur,$searchindex " .
-                         "WHERE cur_id=si_page AND {$this->mTextcond} " .
-                         "{$searchnamespaces} {$redircond} " .
-                         "LIMIT {$offset}, {$limit}";
-                       $res2 = $dbr->query( $sql, $fname );
-                       $num = $num + $dbr->numRows($res2);
-
-                       if ( $num == $limit ) {
-                         $top = wfShowingResults( $offset, $limit);
-                       } else {
-                         $top = wfShowingResultsNum( $offset, $limit, $num );
+               return $parsed;
+       }
+
+       /**
+        * Make a list of searchable namespaces and their canonical names.
+        * @return array
+        */
+       public static function searchableNamespaces() {
+               global $wgContLang;
+               $arr = array();
+               foreach( $wgContLang->getNamespaces() as $ns => $name ) {
+                       if( $ns >= NS_MAIN ) {
+                               $arr[$ns] = $name;
                        }
-                       $wgOut->addHTML( "<p>{$top}</p>\n" );
-       
-                       # For powersearch
+               }
+               return $arr;
+       }
        
-                       $a2l = "" ;
-                       $akk = array_keys( $this->addtoquery ) ;
-                       foreach ( $akk AS $ak ) {
-                               $a2l .= "&{$ak}={$this->addtoquery[$ak]}" ;
+       /**
+        * Extract default namespaces to search from the given user's
+        * settings, returning a list of index numbers.
+        *
+        * @param User $user
+        * @return array
+        * @static 
+        */
+       public static function userNamespaces( &$user ) {
+               $arr = array();
+               foreach( SearchEngine::searchableNamespaces() as $ns => $name ) {
+                       if( $user->getOption( 'searchNs' . $ns ) ) {
+                               $arr[] = $ns;
                        }
+               }
+               return $arr;
+       }
        
-                       $sl = wfViewPrevNext( $offset, $limit, "",
-                         "search=" . wfUrlencode( $this->mUsertext ) . $a2l );
-                       $wgOut->addHTML( "<br />{$sl}\n" );
+       /**
+        * Find snippet highlight settings for a given user
+        *
+        * @param User $user
+        * @return array contextlines, contextchars 
+        * @static
+        */
+       public static function userHighlightPrefs( &$user ){
+               //$contextlines = $user->getOption( 'contextlines',  5 );
+               //$contextchars = $user->getOption( 'contextchars', 50 );
+               $contextlines = 2; // Hardcode this. Old defaults sucked. :)
+               $contextchars = 75; // same as above.... :P
+               return array($contextlines, $contextchars);
+       }
        
-                       $foundsome = false;
+       /**
+        * An array of namespaces indexes to be searched by default
+        * 
+        * @return array 
+        * @static
+        */
+       public static function defaultNamespaces(){
+               global $wgNamespacesToBeSearchedDefault;
+               
+               return array_keys($wgNamespacesToBeSearchedDefault, true);
+       }
+
+       /**
+        * Return a 'cleaned up' search string
+        *
+        * @return string
+        * @access public
+        */
+       function filter( $text ) {
+               $lc = $this->legalSearchChars();
+               return trim( preg_replace( "/[^{$lc}]/", " ", $text ) );
+       }
+       /**
+        * Load up the appropriate search engine class for the currently
+        * active database backend, and return a configured instance.
+        *
+        * @fixme Ask the database class for his default search class
+        * instead of knowing about every backend here.
+        * @return SearchEngine
+        */
+       public static function create() {
+               global $wgDBtype, $wgSearchType;
+               if( $wgSearchType ) {
+                       $class = $wgSearchType;
+               } elseif( $wgDBtype == 'mysql' ) {
+                       $class = 'SearchMySQL';
+               } else if ( $wgDBtype == 'postgres' ) {
+                       $class = 'SearchPostgres';
+               } else if ( $wgDBtype == 'oracle' ) {
+                       $class = 'SearchOracle';
+               } else {
+                       $class = 'SearchEngineDummy';
+               }
+               $search = new $class( wfGetDB( DB_SLAVE ) );
+               $search->setLimitOffset(0,0);
+               return $search;
+       }
+
+       /**
+        * Create or update the search index record for the given page.
+        * Title and text should be pre-processed.
+        *
+        * @param int $id
+        * @param string $title
+        * @param string $text
+        * @abstract
+        */
+       function update( $id, $title, $text ) {
+               // no-op
+       }
+
+       /**
+        * Update a search index record's title only.
+        * Title should be pre-processed.
+        *
+        * @param int $id
+        * @param string $title
+        * @abstract
+        */
+       function updateTitle( $id, $title ) {
+               // no-op
+       }
        
-                       if ( 0 == $dbr->numRows( $res1 ) ) {
-                               $wgOut->addHTML( "<h2>" . wfMsg( "notitlematches" ) .
-                                 "</h2>\n" );
-                       } else {
-                               $foundsome = true;
-                               $off = $offset + 1;
-                               $wgOut->addHTML( "<h2>" . wfMsg( "titlematches" ) .
-                                 "</h2>\n<ol start='{$off}'>" );
+       /**
+        * Get OpenSearch suggestion template
+        * 
+        * @return string
+        * @static 
+        */
+       public static function getOpenSearchTemplate() {
+               global $wgOpenSearchTemplate, $wgServer, $wgScriptPath;
+               if($wgOpenSearchTemplate)               
+                       return $wgOpenSearchTemplate;
+               else{ 
+                       $ns = implode(',',SearchEngine::defaultNamespaces());
+                       if(!$ns) $ns = "0";
+                       return $wgServer . $wgScriptPath . '/api.php?action=opensearch&search={searchTerms}&namespace='.$ns;
+               }
+       }
        
-                               while ( $row = $dbr->fetchObject( $res1 ) ) {
-                                       $this->showHit( $row );
-                               }
-                               $dbr->freeResult( $res1 );
-                               $wgOut->addHTML( "</ol>\n" );
-                       }
+       /**
+        * Get internal MediaWiki Suggest template 
+        * 
+        * @return string
+        * @static
+        */
+       public static function getMWSuggestTemplate() {
+               global $wgMWSuggestTemplate, $wgServer, $wgScriptPath;
+               if($wgMWSuggestTemplate)                
+                       return $wgMWSuggestTemplate;
+               else 
+                       return $wgServer . $wgScriptPath . '/api.php?action=opensearch&search={searchTerms}&namespace={namespaces}';
+       }
+}
 
-                       if ( 0 == $dbr->numRows( $res2 ) ) {
-                               $wgOut->addHTML( "<h2>" . wfMsg( "notextmatches" ) .
-                                 "</h2>\n" );
-                       } else {
-                               $foundsome = true;
-                               $off = $offset + 1;
-                               $wgOut->addHTML( "<h2>" . wfMsg( "textmatches" ) . "</h2>\n" .
-                                 "<ol start='{$off}'>" );
-                               while ( $row = $dbr->fetchObject( $res2 ) ) {
-                                       $this->showHit( $row );
-                               }
-                               $dbr->freeResult( $res2 );
-                               $wgOut->addHTML( "</ol>\n" );
-                       }
-                       if ( ! $foundsome ) {
-                               $wgOut->addHTML( "<p>" . wfMsg( "nonefound" ) . "</p>\n" );
-                       }
-                       $wgOut->addHTML( "<p>{$sl}</p>\n" );
-                       $wgOut->addHTML( $powersearch );
-               }
+/**
+ * @ingroup Search
+ */
+class SearchResultSet {
+       /**
+        * Fetch an array of regular expression fragments for matching
+        * the search terms as parsed by this engine in a text extract.
+        *
+        * @return array
+        * @access public
+        * @abstract
+        */
+       function termMatches() {
+               return array();
        }
 
-       function legalSearchChars()
-       {
-               $lc = "A-Za-z_'0-9\\x80-\\xFF\\-";
-               return $lc;
+       function numRows() {
+               return 0;
        }
 
-       function parseQuery( &$db )
-       {
-               global $wgDBminWordLen, $wgLang, $wgDBmysql4;
+       /**
+        * Return true if results are included in this result set.
+        * @return bool
+        * @abstract
+        */
+       function hasResults() {
+               return false;
+       }
 
-               if( $wgDBmysql4 ) {
-                       # Use cleaner boolean search if available
-                       return $this->parseQuery4( $db );
-               }
-               # on non mysql4 database: get list of words we don't want to search for
-               require_once( "FulltextStoplist.php" );
-
-               $lc = SearchEngine::legalSearchChars() . "()";
-               $q = preg_replace( "/([()])/", " \\1 ", $this->mUsertext );
-               $q = preg_replace( "/\\s+/", " ", $q );
-               $w = explode( " ", trim( $q ) );
-
-               $last = $cond = "";
-               foreach ( $w as $word ) {
-                       $word = $wgLang->stripForSearch( $word );
-                       if ( "and" == $word || "or" == $word || "not" == $word
-                         || "(" == $word || ")" == $word ) {
-                               $cond .= " " . strtoupper( $word );
-                               $last = "";
-                       } else if ( strlen( $word ) < $wgDBminWordLen ) {
-                               continue;
-                       } else if ( FulltextStoplist::inList( $word ) ) {
-                               continue;
-                       } else {
-                               if ( "" != $last ) { $cond .= " AND"; }
-                               $cond .= " (MATCH (##field##) AGAINST ('" .
-                                 $db->strencode( $word ). "'))";
-                               $last = $word;
-                               array_push( $this->mSearchterms, "\\b" . $word . "\\b" );
-                       }
-               }
-               if ( 0 == count( $this->mSearchterms ) ) { return; }
+       /**
+        * Some search modes return a total hit count for the query
+        * in the entire article database. This may include pages
+        * in namespaces that would not be matched on the given
+        * settings.
+        *
+        * Return null if no total hits number is supported.
+        *
+        * @return int
+        * @access public
+        */
+       function getTotalHits() {
+               return null;
+       }
 
-               $this->mTitlecond = "(" . str_replace( "##field##",
-                 "si_title", $cond ) . " )";
+       /**
+        * Some search modes return a suggested alternate term if there are
+        * no exact hits. Returns true if there is one on this set.
+        *
+        * @return bool
+        * @access public
+        */
+       function hasSuggestion() {
+               return false;
+       }
 
-               $this->mTextcond = "(" . str_replace( "##field##",
-                 "si_text", $cond ) . " AND (cur_is_redirect=0) )";
+       /**
+        * @return string suggested query, null if none
+        */
+       function getSuggestionQuery(){
+               return null;
+       }
+
+       /**
+        * @return string highlighted suggested query, '' if none
+        */
+       function getSuggestionSnippet(){
+               return '';
        }
        
-       function parseQuery4( &$db )
-       {
-               global $wgLang;
-               $lc = SearchEngine::legalSearchChars();
-               $searchon = "";
-               $this->mSearchterms = array();
-
-               # FIXME: This doesn't handle parenthetical expressions.
-               if( preg_match_all( '/([-+<>~]?)(([' . $lc . ']+)(\*?)|"[^"]*")/',
-                         $this->mUsertext, $m, PREG_SET_ORDER ) ) {
-                       foreach( $m as $terms ) {
-                               if( $searchon !== "" ) $searchon .= " ";
-                               if( $this->mStrictMatching && ($terms[1] == "") ) {
-                                       $terms[1] = "+";
-                               }
-                               $searchon .= $terms[1] . $wgLang->stripForSearch( $terms[2] );
-                               if( $terms[3] ) {
-                                       $regexp = preg_quote( $terms[3] );
-                                       if( $terms[4] ) $regexp .= "[0-9A-Za-z_]+";
-                               } else {
-                                       $regexp = preg_quote( str_replace( '"', '', $terms[2] ) );
-                               }
-                               $this->mSearchterms[] = $regexp;
-                       }
-                       wfDebug( "Would search with '$searchon'\n" );
-                       wfDebug( "Match with /\b" . implode( '\b|\b', $this->mSearchterms ) . "\b/\n" );
-               } else {
-                       wfDebug( "Can't understand search query '$this->mUsertext'\n" );
-               }
-               
-               $searchon = $db->strencode( $searchon );
-               $this->mTitlecond = " MATCH(si_title) AGAINST('$searchon' IN BOOLEAN MODE)";
-               $this->mTextcond = " (MATCH(si_text) AGAINST('$searchon' IN BOOLEAN MODE) AND cur_is_redirect=0)";
+       /**
+        * Return information about how and from where the results were fetched,
+        * should be useful for diagnostics and debugging 
+        *
+        * @return string
+        */
+       function getInfo() {
+               return null;
        }
+       
+       /**
+        * Return a result set of hits on other (multiple) wikis associated with this one
+        *
+        * @return SearchResultSet
+        */
+       function getInterwikiResults() {
+               return null;
+       }
+       
+       /**
+        * Check if there are results on other wikis
+        *
+        * @return boolean
+        */
+       function hasInterwikiResults() {
+               return $this->getInterwikiResults() != null;
+       }
+       
 
-       function showHit( $row )
-       {
-               global $wgUser, $wgOut, $wgLang;
-
-               $t = Title::makeName( $row->cur_namespace, $row->cur_title );
-               $sk = $wgUser->getSkin();
+       /**
+        * Fetches next search result, or false.
+        * @return SearchResult
+        * @access public
+        * @abstract
+        */
+       function next() {
+               return false;
+       }
 
-               $contextlines = $wgUser->getOption( "contextlines" );
-               if ( "" == $contextlines ) { $contextlines = 5; }
-               $contextchars = $wgUser->getOption( "contextchars" );
-               if ( "" == $contextchars ) { $contextchars = 50; }
+       /**
+        * Frees the result set, if applicable.
+        * @ access public
+        */
+       function free() {
+               // ...
+       }
+}
 
-               $link = $sk->makeKnownLink( $t, "" );
-               $size = wfMsg( "nbytes", strlen( $row->cur_text ) );
-               $wgOut->addHTML( "<li>{$link} ({$size})" );
 
-               $lines = explode( "\n", $row->cur_text );
-               $pat1 = "/(.*)(" . implode( "|", $this->mSearchterms ) . ")(.*)/i";
-               $lineno = 0;
+/**
+ * @ingroup Search
+ */
+class SearchResultTooMany {
+       ## Some search engines may bail out if too many matches are found
+}
 
-               foreach ( $lines as $line ) {
-                       if ( 0 == $contextlines ) {
-                               break;
-                       }
-                       --$contextlines;
-                       ++$lineno;
-                       if ( ! preg_match( $pat1, $line, $m ) ) {
-                               continue;
-                       }
 
-                       $pre = $wgLang->truncate( $m[1], -$contextchars, "..." );
+/**
+ * @fixme This class is horribly factored. It would probably be better to have
+ * a useful base class to which you pass some standard information, then let
+ * the fancy self-highlighters extend that.
+ * @ingroup Search
+ */
+class SearchResult {
+       var $mRevision = null;
 
-                       if ( count( $m ) < 3 ) {
-                               $post = "";
-                       } else {
-                               $post = $wgLang->truncate( $m[3], $contextchars, "..." );
-                       }
+       function SearchResult( $row ) {
+               $this->mTitle = Title::makeTitle( $row->page_namespace, $row->page_title );
+               if( !is_null($this->mTitle) )
+                       $this->mRevision = Revision::newFromTitle( $this->mTitle );
+       }
+       
+       /**
+        * Check if this is result points to an invalid title
+        *
+        * @return boolean
+        * @access public
+        */
+       function isBrokenTitle(){
+               if( is_null($this->mTitle) )
+                       return true;
+               return false;
+       }
+       
+       /**
+        * Check if target page is missing, happens when index is out of date
+        * 
+        * @return boolean
+        * @access public
+        */
+       function isMissingRevision(){
+               if( !$this->mRevision )
+                       return true;
+               return false;
+       }
 
-                       $found = $m[2];
+       /**
+        * @return Title
+        * @access public
+        */
+       function getTitle() {
+               return $this->mTitle;
+       }
 
-                       $line = htmlspecialchars( $pre . $found . $post );
-                       $pat2 = "/(" . implode( "|", $this->mSearchterms ) . ")/i";
-                       $line = preg_replace( $pat2,
-                         "<font color='red'>\\1</font>", $line );
+       /**
+        * @return double or null if not supported
+        */
+       function getScore() {
+               return null;
+       }
 
-                       $wgOut->addHTML( "<br /><small>{$lineno}: {$line}</small>\n" );
+       /**
+        * Lazy initialization of article text from DB
+        */
+       protected function initText(){
+               if( !isset($this->mText) ){
+                       $this->mText = $this->mRevision->getText();
                }
-               $wgOut->addHTML( "</li>\n" );
+       }
+       
+       /**
+        * @param array $terms terms to highlight
+        * @return string highlighted text snippet, null (and not '') if not supported 
+        */
+       function getTextSnippet($terms){
+               global $wgUser, $wgAdvancedSearchHighlighting;
+               $this->initText();
+               list($contextlines,$contextchars) = SearchEngine::userHighlightPrefs($wgUser);
+               $h = new SearchHighlighter();
+               if( $wgAdvancedSearchHighlighting )
+                       return $h->highlightText( $this->mText, $terms, $contextlines, $contextchars );
+               else
+                       return $h->highlightSimple( $this->mText, $terms, $contextlines, $contextchars );
+       }
+       
+       /**
+        * @param array $terms terms to highlight
+        * @return string highlighted title, '' if not supported
+        */
+       function getTitleSnippet($terms){
+               return '';
        }
 
-       function goResult()
-       {
-               global $wgOut, $wgRequest, $wgGoToEdit;
-               global $wgDisableTextSearch;
-               $fname = "SearchEngine::goResult";
-               
-               $search = trim( $wgRequest->getText( "search" ) );
+       /**
+        * @param array $terms terms to highlight
+        * @return string highlighted redirect name (redirect to this page), '' if none or not supported
+        */
+       function getRedirectSnippet($terms){
+               return '';
+       }
 
-               # Try to go to page as entered.
-               #
-               $t = Title::newFromText( $search );
+       /**
+        * @return Title object for the redirect to this page, null if none or not supported
+        */
+       function getRedirectTitle(){
+               return null;
+       }
 
-               # If the string cannot be used to create a title
-               if( false == $t ){ 
-                       $this->showResults();
-                       return;
-               }
+       /**
+        * @return string highlighted relevant section name, null if none or not supported
+        */
+       function getSectionSnippet(){
+               return '';
+       }
 
-               # Exact match? No need to look further.
-               if ( $t->getNamespace() == NS_SPECIAL || 0 != $t->getArticleID() ) {
-                       $wgOut->redirect( $t->getFullURL() );
-                       return;
-               }
+       /**
+        * @return Title object (pagename+fragment) for the section, null if none or not supported
+        */
+       function getSectionTitle(){
+               return null;
+       }
 
-               # Now try all lower case (i.e. first letter capitalized)
-               #
-               $t = Title::newFromText( strtolower( $search ) );
-               if ( 0 != $t->getArticleID() ) {
-                       $wgOut->redirect( $t->getFullURL() );
-                       return;
-               }
+       /**
+        * @return string timestamp
+        */
+       function getTimestamp(){
+               return $this->mRevision->getTimestamp();
+       }
 
-               # Now try capitalized string
-               #
-               $t = Title::newFromText( ucwords( strtolower( $search ) ) );
-               if ( 0 != $t->getArticleID() ) {
-                       $wgOut->redirect( $t->getFullURL() );
-                       return;
-               }
+       /**
+        * @return int number of words
+        */
+       function getWordCount(){
+               $this->initText();
+               return str_word_count( $this->mText );
+       }
 
-               # Now try all upper case
-               #
-               $t = Title::newFromText( strtoupper( $search ) );
-               if ( 0 != $t->getArticleID() ) {
-                       $wgOut->redirect( $t->getFullURL() );
-                       return;
-               }
+       /**
+        * @return int size in bytes
+        */
+       function getByteSize(){
+               $this->initText();
+               return strlen( $this->mText );
+       }
+       
+       /**
+        * @return boolean if hit has related articles
+        */
+       function hasRelated(){
+               return false;
+       }
+       
+       /**
+        * @return interwiki prefix of the title (return iw even if title is broken)
+        */
+       function getInterwikiPrefix(){
+               return '';
+       }
+}
 
-               # Entering an IP address goes to the contributions page
-               if ( preg_match( '/^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}$/', $search ) ) {
-                       $title = Title::makeTitle( NS_SPECIAL, "Contributions" );
-                       $wgOut->redirect( $title->getFullUrl( "target=$search" ) );
-                       return;
+/**
+ * Highlight bits of wikitext
+ * 
+ * @ingroup Search
+ */
+class SearchHighlighter {      
+       var $mCleanWikitext = true;
+       
+       function SearchHighlighter($cleanupWikitext = true){
+               $this->mCleanWikitext = $cleanupWikitext;
+       }
+       
+       /**
+        * Default implementation of wikitext highlighting
+        *
+        * @param string $text
+        * @param array $terms Terms to highlight (unescaped)
+        * @param int $contextlines
+        * @param int $contextchars
+        * @return string
+        */
+       public function highlightText( $text, $terms, $contextlines, $contextchars ) {
+               global $wgLang, $wgContLang;
+               global $wgSearchHighlightBoundaries;
+               $fname = __METHOD__;
+               
+               if($text == '')
+                       return '';
+                               
+               // spli text into text + templates/links/tables
+               $spat = "/(\\{\\{)|(\\[\\[[^\\]:]+:)|(\n\\{\\|)";
+               // first capture group is for detecting nested templates/links/tables/references
+               $endPatterns = array(
+                       1 => '/(\{\{)|(\}\})/', // template
+                       2 => '/(\[\[)|(\]\])/', // image
+                       3 => "/(\n\\{\\|)|(\n\\|\\})/"); // table
+                        
+               // FIXME: this should prolly be a hook or something
+               if(function_exists('wfCite')){
+                       $spat .= '|(<ref>)'; // references via cite extension
+                       $endPatterns[4] = '/(<ref>)|(<\/ref>)/';
                }
-
-               # No match, generate an edit URL
-               $t = Title::newFromText( $this->mRawtext );
+               $spat .= '/';
+               $textExt = array(); // text extracts
+               $otherExt = array();  // other extracts
+               wfProfileIn( "$fname-split" );
+               $start = 0;
+               $textLen = strlen($text);
+               $count = 0; // sequence number to maintain ordering
+               while( $start < $textLen ){
+                       // find start of template/image/table
+                       if( preg_match( $spat, $text, $matches, PREG_OFFSET_CAPTURE, $start ) ){
+                               $epat = '';     
+                               foreach($matches as $key => $val){
+                                       if($key > 0 && $val[1] != -1){
+                                               if($key == 2){
+                                                       // see if this is an image link
+                                                       $ns = substr($val[0],2,-1);
+                                                       if( $wgContLang->getNsIndex($ns) != NS_IMAGE )
+                                                               break;
+                                                       
+                                               }
+                                               $epat = $endPatterns[$key];
+                                               $this->splitAndAdd( $textExt, $count, substr( $text, $start, $val[1] - $start ) );                                              
+                                               $start = $val[1];
+                                               break;
+                                       }
+                               }
+                               if( $epat ){
+                                       // find end (and detect any nested elements)
+                                       $level = 0; 
+                                       $offset = $start + 1;
+                                       $found = false;
+                                       while( preg_match( $epat, $text, $endMatches, PREG_OFFSET_CAPTURE, $offset ) ){
+                                               if( array_key_exists(2,$endMatches) ){
+                                                       // found end
+                                                       if($level == 0){
+                                                               $len = strlen($endMatches[2][0]);
+                                                               $off = $endMatches[2][1];
+                                                               $this->splitAndAdd( $otherExt, $count, 
+                                                                       substr( $text, $start, $off + $len  - $start ) );
+                                                               $start = $off + $len;
+                                                               $found = true;
+                                                               break;
+                                                       } else{
+                                                               // end of nested element
+                                                               $level -= 1;
+                                                       }
+                                               } else{
+                                                       // nested
+                                                       $level += 1;
+                                               }
+                                               $offset = $endMatches[0][1] + strlen($endMatches[0][0]);
+                                       }
+                                       if( ! $found ){
+                                               // couldn't find appropriate closing tag, skip
+                                               $this->splitAndAdd( $textExt, $count, substr( $text, $start, strlen($matches[0][0]) ) );
+                                               $start += strlen($matches[0][0]);
+                                       }
+                                       continue;
+                               }
+                       }
+                       // else: add as text extract
+                       $this->splitAndAdd( $textExt, $count, substr($text,$start) );
+                       break;
+               }
+               
+               $all = $textExt + $otherExt; // these have disjunct key sets
                
-               # If the feature is enabled, go straight to the edit page
-               if ( $wgGoToEdit ) {
-                       $wgOut->redirect( $t->getFullURL( "action=edit" ) );
-                       return;
+               wfProfileOut( "$fname-split" );
+               
+               // prepare regexps
+               foreach( $terms as $index => $term ) {
+                       $terms[$index] = preg_quote( $term, '/' );                      
+                       // manually do upper/lowercase stuff for utf-8 since PHP won't do it
+                       if(preg_match('/[\x80-\xff]/', $term) ){
+                               $terms[$index] = preg_replace_callback('/./us',array($this,'caseCallback'),$terms[$index]);
+                       }
+                       
+                       
                }
+               $anyterm = implode( '|', $terms );
+               $phrase = implode("$wgSearchHighlightBoundaries+", $terms );
+
+               // FIXME: a hack to scale contextchars, a correct solution
+               // would be to have contextchars actually be char and not byte
+               // length, and do proper utf-8 substrings and lengths everywhere,
+               // but PHP is making that very hard and unclean to implement :(
+               $scale = strlen($anyterm) / mb_strlen($anyterm);
+               $contextchars = intval( $contextchars * $scale );
                
-               if( $t ) {
-                       $editurl = $t->escapeLocalURL( "action=edit" );
-               } else {
-                       $editurl = ""; # ?? 
+               $patPre = "(^|$wgSearchHighlightBoundaries)";
+               $patPost = "($wgSearchHighlightBoundaries|$)"; 
+               
+               $pat1 = "/(".$phrase.")/ui";
+               $pat2 = "/$patPre(".$anyterm.")$patPost/ui";
+               
+               wfProfileIn( "$fname-extract" );
+               
+               $left = $contextlines;
+
+               $snippets = array();
+               $offsets = array();             
+               
+               // show beginning only if it contains all words
+               $first = 0;
+               $firstText = '';
+               foreach($textExt as $index => $line){
+                       if(strlen($line)>0 && $line[0] != ';' && $line[0] != ':'){
+                               $firstText = $this->extract( $line, 0, $contextchars * $contextlines );
+                               $first = $index;
+                               break;
+                       }
                }
-               $wgOut->addHTML( "<p>" . wfMsg("nogomatch", $editurl ) . "</p>\n" );
-
-               # Try a fuzzy title search
-               $anyhit = false;
-               global $wgDisableFuzzySearch;
-               if(! $wgDisableFuzzySearch ){
-                       foreach( array(NS_MAIN, NS_WP, NS_USER, NS_IMAGE, NS_MEDIAWIKI) as $namespace){
-                               $anyhit |= SearchEngine::doFuzzyTitleSearch( $search, $namespace );
+               if( $firstText ){
+                       $succ = true;
+                       // check if first text contains all terms
+                       foreach($terms as $term){
+                               if( ! preg_match("/$patPre".$term."$patPost/ui", $firstText) ){
+                                       $succ = false;
+                                       break;
+                               }
+                       }
+                       if( $succ ){
+                               $snippets[$first] = $firstText;
+                               $offsets[$first] = 0; 
                        }
                }
-               
-               if( ! $anyhit ){
-                       return $this->showResults();
+               if( ! $snippets ) {             
+                       // match whole query on text 
+                       $this->process($pat1, $textExt, $left, $contextchars, $snippets, $offsets);
+                       // match whole query on templates/tables/images
+                       $this->process($pat1, $otherExt, $left, $contextchars, $snippets, $offsets);
+                       // match any words on text
+                       $this->process($pat2, $textExt, $left, $contextchars, $snippets, $offsets);
+                       // match any words on templates/tables/images
+                       $this->process($pat2, $otherExt, $left, $contextchars, $snippets, $offsets);
+                       
+                       ksort($snippets);
                }
-       }
-
-       /* static */ function doFuzzyTitleSearch( $search, $namespace ){
-               global $wgLang, $wgOut;
                
-               $this->setupPage();
+               // add extra chars to each snippet to make snippets constant size
+               $extended = array();                                            
+               if( count( $snippets ) == 0){
+                       // couldn't find the target words, just show beginning of article
+                       $targetchars = $contextchars * $contextlines;
+                       $snippets[$first] = '';
+                       $offsets[$first] = 0;
+               } else{
+                       // if begin of the article contains the whole phrase, show only that !! 
+                       if( array_key_exists($first,$snippets) && preg_match($pat1,$snippets[$first]) 
+                           && $offsets[$first] < $contextchars * 2 ){
+                               $snippets = array ($first => $snippets[$first]);
+                       }
+                       
+                       // calc by how much to extend existing snippets
+                       $targetchars = intval( ($contextchars * $contextlines) / count ( $snippets ) );
+               }  
+
+               foreach($snippets as $index => $line){
+                       $extended[$index] = $line;
+                       $len = strlen($line);
+                       if( $len < $targetchars - 20 ){
+                               // complete this line
+                               if($len < strlen( $all[$index] )){
+                                       $extended[$index] = $this->extract( $all[$index], $offsets[$index], $offsets[$index]+$targetchars, $offsets[$index]);
+                                       $len = strlen( $extended[$index] );
+                               }
+                               
+                               // add more lines
+                               $add = $index + 1;
+                               while( $len < $targetchars - 20 
+                                      && array_key_exists($add,$all) 
+                                      && !array_key_exists($add,$snippets) ){
+                                   $offsets[$add] = 0;
+                                   $tt = "\n".$this->extract( $all[$add], 0, $targetchars - $len, $offsets[$add] );
+                                       $extended[$add] = $tt;
+                                       $len += strlen( $tt );
+                                       $add++;                                         
+                               }
+                       } 
+               }
                
-               $sstr = ucfirst($search);
-               $sstr = str_replace(" ", "_", $sstr);
-               $fuzzymatches = SearchEngine::fuzzyTitles( $sstr, $namespace );
-               $fuzzymatches = array_slice($fuzzymatches, 0, 10);
-               $slen = strlen( $search );
-               $wikitext = "";
-               foreach($fuzzymatches as $res){
-                       $t = str_replace("_", " ", $res[1]);
-                       $tfull = $wgLang->getNsText( $namespace ) . ":$t|$t";
-                       if( $namespace == NS_MAIN )
-                               $tfull = "$t";
-                       $distance = $res[0];
-                       $closeness = (strlen( $search ) - $distance) / strlen( $search );
-                       $percent = intval( $closeness * 100 ) . "%";
-                       $stars = str_repeat("*", ceil(5 * $closeness) );
-                       $wikitext .= "* [[$tfull]] $percent ($stars)\n";        
+               //$snippets = array_map('htmlspecialchars', $extended);
+               $snippets = $extended;
+               $last = -1;
+               $extract = '';
+               foreach($snippets as $index => $line){
+                       if($last == -1) 
+                               $extract .= $line; // first line
+                       elseif($last+1 == $index && $offsets[$last]+strlen($snippets[$last]) >= strlen($all[$last]))
+                               $extract .= " ".$line; // continous lines
+                       else
+                               $extract .= '<b> ... </b>' . $line;
+
+                       $last = $index;
                }
-               if( $wikitext ){
-                       if( $namespace != NS_MAIN )
-                               $wikitext = "=== " . $wgLang->getNsText( $namespace ) . " ===\n" . $wikitext;
-                       $wgOut->addWikiText( $wikitext );
-                       return true;
+               if( $extract )
+                       $extract .= '<b> ... </b>';
+               
+               $processed = array();
+               foreach($terms as $term){
+                       if( ! isset($processed[$term]) ){
+                               $pat3 = "/$patPre(".$term.")$patPost/ui"; // highlight word  
+                               $extract = preg_replace( $pat3,
+                                       "\\1<span class='searchmatch'>\\2</span>\\3", $extract );
+                               $processed[$term] = true;
+                       }
                }
-               return false;
+               
+               wfProfileOut( "$fname-extract" );
+               
+               return $extract;
        }
-
-       /* static */ function fuzzyTitles( $sstr, $namespace = NS_MAIN ){
-               $span = 0.10; // weed on title length before doing levenshtein.
-               $tolerance = 0.35; // allowed percentage of erronous characters
-               $slen = strlen($sstr);
-               $tolerance_count = ceil($tolerance * $slen);
-               $spanabs = ceil($slen * (1 + $span)) - $slen;
-               # print "Word: $sstr, len = $slen, range = [$min, $max], tolerance_count = $tolerance_count<BR>\n";
-               $result = array();
-               $cnt = 0;
-               for( $i=0; $i <= $spanabs; $i++ ){
-                       $titles = SearchEngine::getTitlesByLength( $slen + $i, $namespace );
-                       if( $i != 0) {
-                               $titles = array_merge($titles, SearchEngine::getTitlesByLength( $slen - $i, $namespace ) );
-                       }
-                       foreach($titles as $t){
-                               $d = levenshtein($sstr, $t);
-                               if($d < $tolerance_count) 
-                                       $result[] = array($d, $t);
-                               $cnt++;
-                       }
+       
+       /**
+        * Split text into lines and add it to extracts array
+        *
+        * @param array $extracts index -> $line
+        * @param int $count
+        * @param string $text
+        */
+       function splitAndAdd(&$extracts, &$count, $text){
+               $split = explode( "\n", $this->mCleanWikitext? $this->removeWiki($text) : $text );
+               foreach($split as $line){
+                       $tt = trim($line);
+                       if( $tt )
+                               $extracts[$count++] = $tt;
                }
-               usort($result, "SearchEngine_pcmp");
-               return $result;
        }
-
-       /* static */ function getTitlesByLength($aLength, $aNamespace = 0){
-               global $wgMemc, $wgDBname;
-               $fname = 'SearchEngin::getTitlesByLength';
+       
+       /**
+        * Do manual case conversion for non-ascii chars
+        *
+        * @param unknown_type $matches
+        */
+       function caseCallback($matches){
+               global $wgContLang;
+               if( strlen($matches[0]) > 1 ){
+                       return '['.$wgContLang->lc($matches[0]).$wgContLang->uc($matches[0]).']';
+               } else
+                       return $matches[0];
+       }
+       
+       /**
+        * Extract part of the text from start to end, but by
+        * not chopping up words
+        * @param string $text
+        * @param int $start
+        * @param int $end
+        * @param int $posStart (out) actual start position
+        * @param int $posEnd (out) actual end position
+        * @return string  
+        */
+       function extract($text, $start, $end, &$posStart = null, &$posEnd = null ){
+               global $wgContLang;             
+               
+               if( $start != 0)
+                       $start = $this->position( $text, $start, 1 );
+               if( $end >= strlen($text) )
+                       $end = strlen($text);
+               else
+                       $end = $this->position( $text, $end );
+                       
+               if(!is_null($posStart))
+                       $posStart = $start;
+               if(!is_null($posEnd))
+                       $posEnd = $end;
                
-               // to avoid multiple costly SELECTs in case of no memcached
-               if( $this->all_titles ){ 
-                       if( isset( $this->all_titles[$aLength][$aNamespace] ) ){
-                               return $this->all_titles[$aLength][$aNamespace];
-                       } else {
-                               return array();
+               if($end > $start)
+                       return substr($text, $start, $end-$start);
+               else
+                       return '';
+       } 
+       
+       /**
+        * Find a nonletter near a point (index) in the text
+        *
+        * @param string $text
+        * @param int $point
+        * @param int $offset to found index
+        * @return int nearest nonletter index, or beginning of utf8 char if none
+        */
+       function position($text, $point, $offset=0 ){
+               $tolerance = 10;
+               $s = max( 0, $point - $tolerance );
+               $l = min( strlen($text), $point + $tolerance ) - $s;
+               $m = array();
+               if( preg_match('/[ ,.!?~!@#$%^&*\(\)+=\-\\\|\[\]"\'<>]/', substr($text,$s,$l), $m, PREG_OFFSET_CAPTURE ) ){
+                       return $m[0][1] + $s + $offset;
+               } else{
+                       // check if point is on a valid first UTF8 char
+                       $char = ord( $text[$point] );
+                       while( $char >= 0x80 && $char < 0xc0 ) {
+                               // skip trailing bytes
+                               $point++;
+                               if($point >= strlen($text))
+                                       return strlen($text);
+                               $char = ord( $text[$point] );
                        }
+                       return $point;
+                       
                }
-
-               $mkey = "$wgDBname:titlesbylength:$aLength:$aNamespace";
-               $mkeyts = "$wgDBname:titlesbylength:createtime";
-               $ts = $wgMemc->get( $mkeyts );
-               $result = $wgMemc->get( $mkey );
-
-               if( time() - $ts < 3600 ){
-                       // note: in case of insufficient memcached space, we return
-                       // an empty list instead of starting to hit the DB.
-                       return is_array( $result ) ? $result : array();
+       }
+       
+       /**
+        * Search extracts for a pattern, and return snippets
+        *
+        * @param string $pattern regexp for matching lines
+        * @param array $extracts extracts to search   
+        * @param int $linesleft number of extracts to make
+        * @param int $contextchars length of snippet
+        * @param array $out map for highlighted snippets
+        * @param array $offsets map of starting points of snippets
+        * @protected
+        */
+       function process( $pattern, $extracts, &$linesleft, &$contextchars, &$out, &$offsets ){
+               if($linesleft == 0)
+                       return; // nothing to do
+               foreach($extracts as $index => $line){                  
+                       if( array_key_exists($index,$out) )
+                               continue; // this line already highlighted
+                               
+                       $m = array();
+                       if ( !preg_match( $pattern, $line, $m, PREG_OFFSET_CAPTURE ) )
+                               continue;
+                               
+                       $offset = $m[0][1];
+                       $len = strlen($m[0][0]);
+                       if($offset + $len < $contextchars)
+                               $begin = 0; 
+                       elseif( $len > $contextchars)
+                               $begin = $offset;
+                       else
+                               $begin = $offset + intval( ($len - $contextchars) / 2 );
+                       
+                       $end = $begin + $contextchars;
+                       
+                       $posBegin = $begin;
+                       // basic snippet from this line
+                       $out[$index] = $this->extract($line,$begin,$end,$posBegin);
+                       $offsets[$index] = $posBegin;
+                       $linesleft--;                   
+                       if($linesleft == 0)
+                               return;
                }
-
-               $wgMemc->set( $mkeyts, time() );
+       }
+       
+       /** 
+        * Basic wikitext removal
+        * @protected
+        */
+       function removeWiki($text) {
+               $fname = __METHOD__;
+               wfProfileIn( $fname );
                
-               $dbr =& wfGetDB( DB_SLAVE );
-               $res = $dbr->select( 'cur', array( 'cur_title', 'cur_namespace' ), false, $fname );
-               $titles = array(); // length, ns, [titles]
-               while( $obj = $dbr->fetchObject( $res ) ){
-                       $title = $obj->cur_title;
-                       $ns = $obj->cur_namespace;
-                       $len = strlen( $title );
-                       $titles[$len][$ns][] = $title;
-               } 
-               foreach($titles as $length => $length_arr){
-                       foreach($length_arr as $ns => $title_arr){
-                               $mkey = "$wgDBname:titlesbylength:$length:$ns";
-                               $wgMemc->set( $mkey, $title_arr, 3600 * 24 );
-                       }
-               }
-               $this->all_titles = $titles;
-               if( isset( $titles[$aLength][$aNamespace] ) )
-                       return $titles[$aLength][$aNamespace];
+               //$text = preg_replace("/'{2,5}/", "", $text);
+               //$text = preg_replace("/\[[a-z]+:\/\/[^ ]+ ([^]]+)\]/", "\\2", $text);
+               //$text = preg_replace("/\[\[([^]|]+)\]\]/", "\\1", $text);
+               //$text = preg_replace("/\[\[([^]]+\|)?([^|]]+)\]\]/", "\\2", $text);
+               //$text = preg_replace("/\\{\\|(.*?)\\|\\}/", "", $text);
+               //$text = preg_replace("/\\[\\[[A-Za-z_-]+:([^|]+?)\\]\\]/", "", $text);
+               $text = preg_replace("/\\{\\{([^|]+?)\\}\\}/", "", $text);
+               $text = preg_replace("/\\{\\{([^|]+\\|)(.*?)\\}\\}/", "\\2", $text);
+               $text = preg_replace("/\\[\\[([^|]+?)\\]\\]/", "\\1", $text);           
+               $text = preg_replace_callback("/\\[\\[([^|]+\\|)(.*?)\\]\\]/", array($this,'linkReplace'), $text);
+               //$text = preg_replace("/\\[\\[([^|]+\\|)(.*?)\\]\\]/", "\\2", $text);
+               $text = preg_replace("/<\/?[^>]+>/", "", $text);
+               $text = preg_replace("/'''''/", "", $text);
+               $text = preg_replace("/('''|<\/?[iIuUbB]>)/", "", $text);
+               $text = preg_replace("/''/", "", $text);
+               
+               wfProfileOut( $fname );
+               return $text;
+       }
+       
+       /**
+        * callback to replace [[target|caption]] kind of links, if
+        * the target is category or image, leave it
+        *
+        * @param array $matches
+        */
+       function linkReplace($matches){
+               $colon = strpos( $matches[1], ':' ); 
+               if( $colon === false )
+                       return $matches[2]; // replace with caption
+               global $wgContLang;
+               $ns = substr( $matches[1], 0, $colon );
+               $index = $wgContLang->getNsIndex($ns);
+               if( $index !== false && ($index == NS_IMAGE || $index == NS_CATEGORY) )
+                       return $matches[0]; // return the whole thing 
                else
-                       return array();
+                       return $matches[2];
+               
        }
-}
 
-/* private static */ function SearchEngine_pcmp($a, $b){ return $a[0] - $b[0]; }
+       /**
+     * Simple & fast snippet extraction, but gives completely unrelevant
+     * snippets
+     *
+     * @param string $text
+     * @param array $terms
+     * @param int $contextlines
+     * @param int $contextchars
+     * @return string
+     */
+    public function highlightSimple( $text, $terms, $contextlines, $contextchars ) {
+        global $wgLang, $wgContLang;
+        $fname = __METHOD__;
+    
+        $lines = explode( "\n", $text );
+        
+        $terms = implode( '|', $terms );
+        $terms = str_replace( '/', "\\/", $terms);
+        $max = intval( $contextchars ) + 1;
+        $pat1 = "/(.*)($terms)(.{0,$max})/i";
+
+        $lineno = 0;
+
+        $extract = "";
+        wfProfileIn( "$fname-extract" );
+        foreach ( $lines as $line ) {
+            if ( 0 == $contextlines ) {
+                break;
+            }
+            ++$lineno;
+            $m = array();
+            if ( ! preg_match( $pat1, $line, $m ) ) {
+                continue;
+            }
+            --$contextlines;
+            $pre = $wgContLang->truncate( $m[1], -$contextchars, ' ... ' );
+
+            if ( count( $m ) < 3 ) {
+                $post = '';
+            } else {
+                $post = $wgContLang->truncate( $m[3], $contextchars, ' ... ' );
+            }
+
+            $found = $m[2];
+
+            $line = htmlspecialchars( $pre . $found . $post );
+            $pat2 = '/(' . $terms . ")/i";
+            $line = preg_replace( $pat2,
+              "<span class='searchmatch'>\\1</span>", $line );
+
+            $extract .= "${line}\n";
+        }
+        wfProfileOut( "$fname-extract" );
+        
+        return $extract;
+    }
+       
+}
 
-?>
+/**
+ * Dummy class to be used when non-supported Database engine is present.
+ * @fixme Dummy class should probably try something at least mildly useful,
+ * such as a LIKE search through titles.
+ * @ingroup Search
+ */
+class SearchEngineDummy extends SearchEngine {
+       // no-op
+}