public function processModifierParameter()
    {
        if ($this->_lastToken === null) {
            include_once 'Zend/Search/Lucene/Search/QueryParserException.php';
            throw new Zend_Search_Lucene_Search_QueryParserException('Lexeme modifier parameter must follow lexeme modifier. Char position 0.');
        }

        switch ($this->_lastToken->type) {
        case Zend_Search_Lucene_Search_QueryToken::TT_FUZZY_PROX_MARK:
            $this->_context->processFuzzyProximityModifier($this->_currentToken->text);
            break;

        case Zend_Search_Lucene_Search_QueryToken::TT_BOOSTING_MARK:
            $this->_context->boost($this->_currentToken->text);
            break;

        default:
            // It's not a user input exception
            include_once 'Zend/Search/Lucene/Exception.php';
            throw new Zend_Search_Lucene_Exception('Lexeme modifier parameter must follow lexeme modifier. Char position 0.');
        }
    }