问截断文本块末尾的HTML内容(块元素)

EN

    public static HtmlNode TruncateInnerText(HtmlNode node, int length)
    {
        if (node == null)
            throw new ArgumentNullException("node");

        // nothing to do?
        if (node.InnerText.Length < length)
            return node;

        HtmlNode clone = node.CloneNode(false);
        TruncateInnerText(node, clone, clone, length);
        return clone;
    }

    private static void TruncateInnerText(HtmlNode source, HtmlNode root, HtmlNode current, int length)
    {
        HtmlNode childClone;
        foreach (HtmlNode child in source.ChildNodes)
        {
            // is expected size is ok?
            int expectedSize = child.InnerText.Length + root.InnerText.Length;
            if (expectedSize <= length)
            {
                // yes, just clone the whole hierarchy
                childClone = child.CloneNode(true);
                current.ChildNodes.Add(childClone);
                continue;
            }

            // is it a text node? then crop it
            HtmlTextNode text = child as HtmlTextNode;
            if (text != null)
            {
                int remove = expectedSize - length;
                childClone = root.OwnerDocument.CreateTextNode(text.InnerText.Substring(0, text.InnerText.Length - remove));
                current.ChildNodes.Add(childClone);
                return;
            }

            // it's not a text node, shallow clone and dive in
            childClone = child.CloneNode(false);
            current.ChildNodes.Add(childClone);
            TruncateInnerText(child, root, childClone, length);
        }
    }

  class Program
  {
      static void Main(string[] args)
      {
          var web = new HtmlWeb();
          var doc = web.Load("http://stackoverflow.com/questions/30926684/truncating-html-content-at-the-end-of-text-blocks-block-elements");
          var post = doc.DocumentNode.SelectSingleNode("//td[@class='postcell']//div[@class='post-text']");
          var truncated = TruncateInnerText(post, 500);
          Console.WriteLine(truncated.OuterHtml);
          Console.WriteLine("Size: " + truncated.InnerText.Length);
      }
  }

<div class="post-text" itemprop="text">

<p>Mainly when we shorten/truncate textual content we usually just truncate it at specific character index. That's already complicated in HTML anyway, but I want to truncate my HTML content (generated using content-editable <code>div</code>) using different measures:</p>

<ol>
<li>I would define character index <code>N</code> that will serve as truncating startpoint <em>limit</em></li>
<li>Algorithm will check whether content is at least <code>N</code> characters long (text only; not counting tags); if it's not it will just return the whole content</li>
<li>It would then</li></ol></div>
Size: 500

   private void RemoveEmpty(HtmlNode node){
       var parent = node.Parent;
       node.Remove();
       if(parent==null)
           return;
       // remove parent if it is empty
       if(!parent.DescendantNodes.Any()){
           RemoveEmpty(parent);
       }
   }



private void Truncate(DocumentNode root, int maxLimit){

    var n = 0;
    HtmlTextNode lastNode = null;

    foreach(var node in root.DescendantNodes
         .OfType<HtmlTextNode>().ToArray()){
       var length = node.Text.Length;

       n+= length;
       if(n + length >= maxLimit){
            RemoveEmpty(node);
       }

    }
}

// you are left with only nodes that add up to your max limit characters.