public function finishExpression()
    {
        if ($this->getState() != self::ST_LITERAL) {
            include_once 'Zend/Search/Lucene/Exception.php';
            throw new Zend_Search_Lucene_Exception('Literal expected.');
        }

        $this->_conjunctions[] = $this->_currentConjunction;

        return $this->_conjunctions;
    }