protected function _parse_quotes()
    {
        // Matches quote types
        $re = '/(\'[^\']*\')|(\"[^\"]*\")/';

        $quotes = $this->_frame->get_style()->quotes;

        // split on spaces, except within quotes
        if (!preg_match_all($re, "$quotes", $matches, PREG_SET_ORDER)) {
            return null;
        }

        $quotes_array = array();
        foreach ($matches as $_quote) {
            $quotes_array[] = $this->_parse_string($_quote[0], true);
        }

        if (empty($quotes_array)) {
            $quotes_array = array('"', '"');
        }

        return array_chunk($quotes_array, 2);
    }