大家帮忙看上解析自定义标签有关问题

<div>  <ul>    <!--{$news num="10" classid="1" bytype="0"}-->    <li><a href="{news.url}" target="_blank"{news.style}>·{news.i}、{news.title}</a>{news.AddTime dateformat="mm-dd"}</li>    <!--{/$news}-->  </ul></div>

        public string NewsList(string content)        {            string Attributes = "";            string Text = "";            string AllText = "";            Regex r = new Regex(@"(\{\$news\s+(?<attributes>[^\]]*?)\}(?<text>[\s\S]*?)\{/\$news\})", RegexOptions.Compiled | RegexOptions.IgnoreCase);            foreach (Match m in r.Matches(content))            {                Attributes = m.Groups["attributes"].ToString();                Text = m.Groups["text"].ToString();                AllText = m.Groups[0].Value.ToString();                string TopNum = null;                TopNum = GetAttr(Attributes, "num");                if (TopNum != null)                {                    TopNum = " Top " + TopNum + " ";                }                string strSQL = "Select " + TopNum + " * From HL_News Where 1 = 1 ";                string ClassId = null;                ClassId = GetAttr(Attributes, "classid");                if (ClassId != null)                {                    strSQL += " And ClassId = " + ClassId + " ";                }                strSQL += " Order By id Desc ";                SqlConnection con = dbConn.GetConn();                con.Open();                SqlDataAdapter da = new SqlDataAdapter(strSQL, con);                DataSet ds = new DataSet();                da.Fill(ds);                if (ds.Tables[0].Rows.Count > 0)                {                    int index = 1;                    StringBuilder str = new StringBuilder();                    foreach (DataRow dr in ds.Tables[0].Rows)                    {                        StringBuilder txt = new StringBuilder();                        txt.Append(Text);                        txt = txt.Replace("{news.classid}", dr["classid"].ToString());                        txt = txt.Replace("{news.title}", dr["title"].ToString());                        txt = txt.Replace("{news.url}", dr["id"].ToString());                        txt = txt.Replace("{news.i}", index.ToString());                        index++;                        str.Append(txt);                    }                    content = content.Replace(AllText, str.ToString());                }            }            return content;        }        /// <summary>        /// 获取属性的值        /// </summary>        /// <param name="tag">str</param>        /// <param name="tagName">属性名称</param>        /// <returns>属性的值</returns>        private string GetAttr(string tag, string tagName)        {            Regex r = new Regex(@"(?<key>\w+)\s*=\s*(?<value>" + "\"" + "[^\"]*\")", RegexOptions.Compiled | RegexOptions.IgnoreCase);            foreach (Match m in r.Matches(tag))            {                if (m.Groups["key"].ToString().Trim().ToLower() == tagName.ToLower())                {                    return m.Groups["value"].ToString().ToLower().Replace("\"", "");                }            }            return null;        }