Repeater多列分别合并单元格

GridView、Repeater合并单元格可以参考http://www.cnblogs.com/zhmore/archive/2009/04/22/1440979.html，但是原文例子是合并一列的单元格。
现在有2列需要分别合并单元格，如下所示，“类型”和“操作”当有相同的值时要分别合并：

可以在原来的代码上稍做改动，前台代码如下：

<asp:Repeater runat="server" ID="rptList">         
<HeaderTemplate>
   <table width="100%" border="1" cellpadding="4" cellspacing="0" bgcolor="#464646" style="border-collapse:collapse; padding:0; margin:0">  
       <tr bgcolor="#eeeeee">  
           <td>序号</td> 
           <td>类型</td>
           <td>操作</td>
           <td>编号</td>                                        
       </tr>   
</HeaderTemplate>                 
  <ItemTemplate>
   <tr bgcolor="#ffffff">                                   
           <td><%# Eval("rn") %></td>
           <td runat="server" id="td1"><%#Eval("Col1")%></td>
           <td runat="server" id="td2"><%#Eval("Col2")%></td>
           <td><%#Eval("Col3")%></td> 
           <td><%#Eval("Col4")%></td> 
       </tr>
  </ItemTemplate>   
  <FooterTemplate>
     </table>  
  </FooterTemplate>                       
</asp:Repeater> 

 后台代码如下：

private void BindData()
{
    rptList.DataSource = null; //这里为数据源，省略...
    rptList.DataBind();  
    MergeCell("td1", "td2");
}
private void MergeCell(string tdIdName1, string tdIdName2)
{
    for (int i = rptList.Items.Count - 1; i > 0; i--)
    {
        MergeCellSet(tdIdName1, tdIdName2, i);
    }
}
private void MergeCellSet(string tdIdName1, string tdIdName2, int i)
{
    HtmlTableCell cellPrev = rptList.Items[i - 1].FindControl(tdIdName1) as HtmlTableCell;
    HtmlTableCell cell = rptList.Items[i].FindControl(tdIdName1) as HtmlTableCell;
    cell.RowSpan = (cell.RowSpan == -1) ? 1 : cell.RowSpan;
    cellPrev.RowSpan = (cellPrev.RowSpan == -1) ? 1 : cellPrev.RowSpan;
    if (cell.InnerText == cellPrev.InnerText)
    {
        cell.Visible = false;
        cellPrev.RowSpan += cell.RowSpan;

        //关键代码，再判断执行第2列的合并单元格方法
        if (tdIdName2 != "") MergeCellSet(tdIdName2, "", i);
    }
}