SearchEngine.php

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<?php
class SearchEngine {
    var $limit = 10;
    var $offset = 0;
    var $prefix = '';
    var $searchTerms = array();
    var $namespaces = array( NS_MAIN );
    var $showRedirects = false;

    protected $features = array();

    protected $db;

    function __construct( $db = null ) {
        if ( $db ) {
            $this->db = $db;
        } else {
            $this->db = wfGetDB( DB_SLAVE );
        }
    }

    function searchText( $term ) {
        return null;
    }

    function searchTitle( $term ) {
        return null;
    }

    function acceptListRedirects() {
        wfDeprecated( __METHOD__, '1.18' );
        return $this->supports( 'list-redirects' );
    }

    public function supports( $feature ) {
        switch ( $feature ) {
        case 'list-redirects':
        case 'search-update':
            return true;
        case 'title-suffix-filter':
        default:
            return false;
        }
    }

    public function setFeatureData( $feature, $data ) {
        $this->features[$feature] = $data;
    }

    public function normalizeText( $string ) {
        global $wgContLang;

        // Some languages such as Chinese require word segmentation
        return $wgContLang->segmentByWord( $string );
    }

    function transformSearchTerm( $term ) {
        return $term;
    }

    public static function getNearMatch( $searchterm ) {
        $title = self::getNearMatchInternal( $searchterm );

        wfRunHooks( 'SearchGetNearMatchComplete', array( $searchterm, &$title ) );
        return $title;
    }

    public static function getNearMatchResultSet( $searchterm ) {
        return new SearchNearMatchResultSet( self::getNearMatch( $searchterm ) );
    }

    private static function getNearMatchInternal( $searchterm ) {
        global $wgContLang, $wgEnableSearchContributorsByIP;

        $allSearchTerms = array( $searchterm );

        if ( $wgContLang->hasVariants() ) {
            $allSearchTerms = array_merge( $allSearchTerms, $wgContLang->autoConvertToAllVariants( $searchterm ) );
        }

        $titleResult = null;
        if ( !wfRunHooks( 'SearchGetNearMatchBefore', array( $allSearchTerms, &$titleResult ) ) ) {
            return $titleResult;
        }

        foreach ( $allSearchTerms as $term ) {

            # Exact match? No need to look further.
            $title = Title::newFromText( $term );
            if ( is_null( $title ) ) {
                return null;
            }

            # Try files if searching in the Media: namespace
            if ( $title->getNamespace() == NS_MEDIA ) {
                $title = Title::makeTitle( NS_FILE, $title->getText() );
            }

            if ( $title->isSpecialPage() || $title->isExternal() || $title->exists() ) {
                return $title;
            }

            # See if it still otherwise has content is some sane sense
            $page = WikiPage::factory( $title );
            if ( $page->hasViewableContent() ) {
                return $title;
            }

            if ( !wfRunHooks( 'SearchAfterNoDirectMatch', array( $term, &$title ) ) ) {
                return $title;
            }

            # Now try all lower case (i.e. first letter capitalized)
            $title = Title::newFromText( $wgContLang->lc( $term ) );
            if ( $title && $title->exists() ) {
                return $title;
            }

            # Now try capitalized string
            $title = Title::newFromText( $wgContLang->ucwords( $term ) );
            if ( $title && $title->exists() ) {
                return $title;
            }

            # Now try all upper case
            $title = Title::newFromText( $wgContLang->uc( $term ) );
            if ( $title && $title->exists() ) {
                return $title;
            }

            # Now try Word-Caps-Breaking-At-Word-Breaks, for hyphenated names etc
            $title = Title::newFromText( $wgContLang->ucwordbreaks( $term ) );
            if ( $title && $title->exists() ) {
                return $title;
            }

            // Give hooks a chance at better match variants
            $title = null;
            if ( !wfRunHooks( 'SearchGetNearMatch', array( $term, &$title ) ) ) {
                return $title;
            }
        }

        $title = Title::newFromText( $searchterm );

        # Entering an IP address goes to the contributions page
        if ( $wgEnableSearchContributorsByIP ) {
            if ( ( $title->getNamespace() == NS_USER && User::isIP( $title->getText() ) )
                || User::isIP( trim( $searchterm ) ) ) {
                return SpecialPage::getTitleFor( 'Contributions', $title->getDBkey() );
            }
        }

        # Entering a user goes to the user page whether it's there or not
        if ( $title->getNamespace() == NS_USER ) {
            return $title;
        }

        # 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_FILE ) {
            $image = wfFindFile( $title );
            if ( $image ) {
                return $title;
            }
        }

        # 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() ) );
        }

        # Quoted term? Try without the quotes...
        $matches = array();
        if ( preg_match( '/^"([^"]+)"$/', $searchterm, $matches ) ) {
            return SearchEngine::getNearMatch( $matches[1] );
        }

        return null;
    }

    public static function legalSearchChars() {
        return "A-Za-z_'.0-9\\x80-\\xFF\\-";
    }

    function setLimitOffset( $limit, $offset = 0 ) {
        $this->limit = intval( $limit );
        $this->offset = intval( $offset );
    }

    function setNamespaces( $namespaces ) {
        $this->namespaces = $namespaces;
    }

    function replacePrefixes( $query ) {
        global $wgContLang;

        $parsed = $query;
        if ( strpos( $query, ':' ) === false ) { // nothing to do
            wfRunHooks( 'SearchEngineReplacePrefixesComplete', array( $this, $query, &$parsed ) );
            return $parsed;
        }

        $allkeyword = wfMessage( 'searchall' )->inContentLanguage()->text() . ":";
        if ( strncmp( $query, $allkeyword, strlen( $allkeyword ) ) == 0 ) {
            $this->namespaces = null;
            $parsed = substr( $query, strlen( $allkeyword ) );
        } elseif ( 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 );
            }
        }
        if ( trim( $parsed ) == '' ) {
            $parsed = $query; // prefix was the whole query
        }

        wfRunHooks( 'SearchEngineReplacePrefixesComplete', array( $this, $query, &$parsed ) );

        return $parsed;
    }

    public static function searchableNamespaces() {
        global $wgContLang;
        $arr = array();
        foreach ( $wgContLang->getNamespaces() as $ns => $name ) {
            if ( $ns >= NS_MAIN ) {
                $arr[$ns] = $name;
            }
        }

        wfRunHooks( 'SearchableNamespaces', array( &$arr ) );
        return $arr;
    }

    public static function userNamespaces( $user ) {
        global $wgSearchEverythingOnlyLoggedIn;

        $searchableNamespaces = SearchEngine::searchableNamespaces();

        // get search everything preference, that can be set to be read for logged-in users
        // it overrides other options
        if ( !$wgSearchEverythingOnlyLoggedIn || $user->isLoggedIn() ) {
            if ( $user->getOption( 'searcheverything' ) ) {
                return array_keys( $searchableNamespaces );
            }
        }

        $arr = array();
        foreach ( $searchableNamespaces as $ns => $name ) {
            if ( $user->getOption( 'searchNs' . $ns ) ) {
                $arr[] = $ns;
            }
        }

        return $arr;
    }

    public static function userHighlightPrefs() {
        $contextlines = 2; // Hardcode this. Old defaults sucked. :)
        $contextchars = 75; // same as above.... :P
        return array( $contextlines, $contextchars );
    }

    public static function defaultNamespaces() {
        global $wgNamespacesToBeSearchedDefault;

        return array_keys( $wgNamespacesToBeSearchedDefault, true );
    }

    public static function namespacesAsText( $namespaces ) {
        global $wgContLang;

        $formatted = array_map( array( $wgContLang, 'getFormattedNsText' ), $namespaces );
        foreach ( $formatted as $key => $ns ) {
            if ( empty( $ns ) ) {
                $formatted[$key] = wfMessage( 'blanknamespace' )->text();
            }
        }
        return $formatted;
    }

    public static function helpNamespaces() {
        global $wgNamespacesToBeSearchedHelp;

        return array_keys( $wgNamespacesToBeSearchedHelp, true );
    }

    function filter( $text ) {
        $lc = $this->legalSearchChars();
        return trim( preg_replace( "/[^{$lc}]/", " ", $text ) );
    }
    public static function create( $type = null ) {
        global $wgSearchType;
        $dbr = null;

        $alternatives = self::getSearchTypes();

        if ( $type && in_array( $type, $alternatives ) ) {
            $class = $type;
        } elseif ( $wgSearchType !== null ) {
            $class = $wgSearchType;
        } else {
            $dbr = wfGetDB( DB_SLAVE );
            $class = $dbr->getSearchEngine();
        }

        $search = new $class( $dbr );
        $search->setLimitOffset( 0, 0 );
        return $search;
    }

    public static function getSearchTypes() {
        global $wgSearchType, $wgSearchTypeAlternatives;
        static $alternatives = null;
        if ( $alternatives === null ) {
            $alternatives = $wgSearchTypeAlternatives ?: array();
            array_unshift( $alternatives, $wgSearchType );
        }
        return $alternatives;
    }

    function update( $id, $title, $text ) {
        // no-op
    }

    function updateTitle( $id, $title ) {
        // no-op
    }

    function delete( $id, $title ) {
        // no-op
    }

    public static function getOpenSearchTemplate() {
        global $wgOpenSearchTemplate, $wgCanonicalServer;
        if ( $wgOpenSearchTemplate ) {
            return $wgOpenSearchTemplate;
        } else {
            $ns = implode( '|', SearchEngine::defaultNamespaces() );
            if ( !$ns ) {
                $ns = "0";
            }
            return $wgCanonicalServer . wfScript( 'api' ) . '?action=opensearch&search={searchTerms}&namespace=' . $ns;
        }
    }

    public function getTextFromContent( Title $t, Content $c = null ) {
        return $c ? $c->getTextForSearchIndex() : '';
    }

    public function textAlreadyUpdatedForIndex() {
        return false;
    }
}

class SearchResultSet {
    function termMatches() {
        return array();
    }

    function numRows() {
        return 0;
    }

    function hasResults() {
        return false;
    }

    function getTotalHits() {
        return null;
    }

    function hasSuggestion() {
        return false;
    }

    function getSuggestionQuery() {
        return null;
    }

    function getSuggestionSnippet() {
        return '';
    }

    function getInfo() {
        return null;
    }

    function getInterwikiResults() {
        return null;
    }

    function hasInterwikiResults() {
        return $this->getInterwikiResults() != null;
    }

    function next() {
        return false;
    }

    function free() {
        // ...
    }
}

class SqlSearchResultSet extends SearchResultSet {

    protected $mResultSet;

    function __construct( $resultSet, $terms ) {
        $this->mResultSet = $resultSet;
        $this->mTerms = $terms;
    }

    function termMatches() {
        return $this->mTerms;
    }

    function numRows() {
        if ( $this->mResultSet === false ) {
            return false;
        }

        return $this->mResultSet->numRows();
    }

    function next() {
        if ( $this->mResultSet === false ) {
            return false;
        }

        $row = $this->mResultSet->fetchObject();
        if ( $row === false ) {
            return false;
        }

        return SearchResult::newFromRow( $row );
    }

    function free() {
        if ( $this->mResultSet === false ) {
            return false;
        }

        $this->mResultSet->free();
    }
}

class SearchResultTooMany {
    # # Some search engines may bail out if too many matches are found
}

class SearchResult {

    var $mRevision = null;
    var $mImage = null;

    var $mTitle;

    var $mText;

    public static function newFromTitle( $title ) {
        $result = new self();
        $result->initFromTitle( $title );
        return $result;
    }
    public static function newFromRow( $row ) {
        $result = new self();
        $result->initFromRow( $row );
        return $result;
    }

    public function __construct( $row = null ) {
        if ( !is_null( $row ) ) {
            // Backwards compatibility with pre-1.17 callers
            $this->initFromRow( $row );
        }
    }

    protected function initFromRow( $row ) {
        $this->initFromTitle( Title::makeTitle( $row->page_namespace, $row->page_title ) );
    }

    protected function initFromTitle( $title ) {
        $this->mTitle = $title;
        if ( !is_null( $this->mTitle ) ) {
            $id = false;
            wfRunHooks( 'SearchResultInitFromTitle', array( $title, &$id ) );
            $this->mRevision = Revision::newFromTitle(
                $this->mTitle, $id, Revision::READ_NORMAL );
            if ( $this->mTitle->getNamespace() === NS_FILE ) {
                $this->mImage = wfFindFile( $this->mTitle );
            }
        }
    }

    function isBrokenTitle() {
        if ( is_null( $this->mTitle ) ) {
            return true;
        }
        return false;
    }

    function isMissingRevision() {
        return !$this->mRevision && !$this->mImage;
    }

    function getTitle() {
        return $this->mTitle;
    }

    function getScore() {
        return null;
    }

    protected function initText() {
        if ( !isset( $this->mText ) ) {
            if ( $this->mRevision != null ) {
                $this->mText = SearchEngine::create()
                    ->getTextFromContent( $this->mTitle, $this->mRevision->getContent() );
            } else { // TODO: can we fetch raw wikitext for commons images?
                $this->mText = '';
            }
        }
    }

    function getTextSnippet( $terms ) {
        global $wgAdvancedSearchHighlighting;
        $this->initText();

        // TODO: make highliter take a content object. Make ContentHandler a factory for SearchHighliter.
        list( $contextlines, $contextchars ) = SearchEngine::userHighlightPrefs();
        $h = new SearchHighlighter();
        if ( $wgAdvancedSearchHighlighting ) {
            return $h->highlightText( $this->mText, $terms, $contextlines, $contextchars );
        } else {
            return $h->highlightSimple( $this->mText, $terms, $contextlines, $contextchars );
        }
    }

    function getTitleSnippet( $terms ) {
        return '';
    }

    function getRedirectSnippet( $terms ) {
        return '';
    }

    function getRedirectTitle() {
        return null;
    }

    function getSectionSnippet() {
        return '';
    }

    function getSectionTitle() {
        return null;
    }

    function getTimestamp() {
        if ( $this->mRevision ) {
            return $this->mRevision->getTimestamp();
        } elseif ( $this->mImage ) {
            return $this->mImage->getTimestamp();
        }
        return '';
    }

    function getWordCount() {
        $this->initText();
        return str_word_count( $this->mText );
    }

    function getByteSize() {
        $this->initText();
        return strlen( $this->mText );
    }

    function hasRelated() {
        return false;
    }

    function getInterwikiPrefix() {
        return '';
    }
}
class SearchNearMatchResultSet extends SearchResultSet {
    private $fetched = false;
    public function __construct( $match ) {
        $this->result = $match;
    }
    public function hasResult() {
        return (bool)$this->result;
    }
    public function numRows() {
        return $this->hasResults() ? 1 : 0;
    }
    public function next() {
        if ( $this->fetched || !$this->result ) {
            return false;
        }
        $this->fetched = true;
        return SearchResult::newFromTitle( $this->result );
    }
}

class SearchHighlighter {
    var $mCleanWikitext = true;

    function __construct( $cleanupWikitext = true ) {
        $this->mCleanWikitext = $cleanupWikitext;
    }

    public function highlightText( $text, $terms, $contextlines, $contextchars ) {
        global $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

        // @todo FIXME: This should prolly be a hook or something
        if ( function_exists( 'wfCite' ) ) {
            $spat .= '|(<ref>)'; // references via cite extension
            $endPatterns[4] = '/(<ref>)|(<\/ref>)/';
        }
        $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_FILE ) {
                                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

        wfProfileOut( "$fname-split" );

        // prepare regexps
        foreach ( $terms as $index => $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] );
            } else {
                $terms[$index] = $term;
            }
        }
        $anyterm = implode( '|', $terms );
        $phrase = implode( "$wgSearchHighlightBoundaries+", $terms );

        // @todo 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 );

        $patPre = "(^|$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;
            }
        }
        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 ( ! $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 );
        }

        // 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
            if ( array_key_exists( $first, $all ) ) {
                $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++;
                }
            }
        }

        // $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 ( $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;
            }
        }

        wfProfileOut( "$fname-extract" );

        return $extract;
    }

    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;
            }
        }
    }

    function caseCallback( $matches ) {
        global $wgContLang;
        if ( strlen( $matches[0] ) > 1 ) {
            return '[' . $wgContLang->lc( $matches[0] ) . $wgContLang->uc( $matches[0] ) . ']';
        } else {
            return $matches[0];
        }
    }

    function extract( $text, $start, $end, &$posStart = null, &$posEnd = null ) {
        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;
        }

        if ( $end > $start ) {
            return substr( $text, $start, $end - $start );
        } else {
            return '';
        }
    }

    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;

        }
    }

    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;
            }
        }
    }

    function removeWiki( $text ) {
        $fname = __METHOD__;
        wfProfileIn( $fname );

        // $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;
    }

    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_FILE || $index == NS_CATEGORY ) ) {
            return $matches[0]; // return the whole thing
        } else {
            return $matches[2];
        }
    }

    public function highlightSimple( $text, $terms, $contextlines, $contextchars ) {
        global $wgContLang;
        $fname = __METHOD__;

        $lines = explode( "\n", $text );

        $terms = implode( '|', $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;
            // truncate function changes ... to relevant i18n message.
            $pre = $wgContLang->truncate( $m[1], - $contextchars, '...', false );

            if ( count( $m ) < 3 ) {
                $post = '';
            } else {
                $post = $wgContLang->truncate( $m[3], $contextchars, '...', false );
            }

            $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;
    }

}

class SearchEngineDummy extends SearchEngine {
    // no-op
}