function tagMatcher($tag_name, $close_tags = null)
    {
        $expr = $this->_tag_expr;

        if ($close_tags) {
            $options = implode("|", array_merge(array($tag_name), $close_tags));
            $closer = sprintf("(?:%s)", $options);
        } else {
            $closer = $tag_name;
        }

        $expr = sprintf($expr, $tag_name, $closer);
        return sprintf("/%s/%s", $expr, $this->_re_flags);
    }