public function addEntry(Zend_Search_Lucene_Search_QueryEntry $entry)
    {
        if ($this->_mode !== self::GM_BOOLEAN) {
            $this->_signs[] = $this->_nextEntrySign;
        }

        $this->_entries[] = $entry;

        $this->_nextEntryField = null;
        $this->_nextEntrySign  = null;
    }