Html Agility Pack is the best technique to integrate nodes.

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Html Agility Pack is the best technique to integrate nodes.

c# html-agility-pack

Question

I converted a large Word manuscript to HTML. It's close, however I want to combine many "code" nodes into a single "pre" node.

Now for the input:

<p>Here's a sample MVC Controller action:</p>
<code>        public ActionResult Index()</code>
<code>        {</code>
<code>            return View();</code>
<code>        }</code>
<p>We'll start by making the following changes...</p>

Instead, I would want to change it to this:

<p>Here's a sample MVC Controller action:</p>
<pre class="brush: csharp">        public ActionResult Index()
    {
        return View();
    }</pre>
<p>We'll start by making the following changes...</p>

I finally came up with a brute-force loop that iterates nodes in search of consecutive ones, however I think this is ugly:

HtmlDocument doc = new HtmlDocument();
doc.Load(file);

var nodes = doc.DocumentNode.ChildNodes;
string contents = string.Empty;

foreach (HtmlNode node in nodes)
{

    if (node.Name == "code")
    {
        contents += node.InnerText + Environment.NewLine;
        if (node.NextSibling.Name != "code" && 
            !(node.NextSibling.Name == "#text" && node.NextSibling.NextSibling.Name == "code")
            )
        {
            node.Name = "pre";
            node.Attributes.RemoveAll();
            node.SetAttributeValue("class", "brush: csharp");
            node.InnerHtml = contents;
            contents = string.Empty;
        }
    }
}

nodes = doc.DocumentNode.SelectNodes(@"//code");
foreach (var node in nodes)
{
    node.Remove();
}

Normally, I'd delete the nodes in the first loop, but you can't alter the collection while you traverse over it, so it doesn't work throughout iteration.

better concepts?

Jon Galloway

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Alex · Accepted Answer · 3/23/2012 12:42:04 PM

The first strategy is to choose all of<code> build a collection of nodes, then a<pre> per-group node:

var idx = 0;
var nodes = doc.DocumentNode
    .SelectNodes("//code")
    .GroupBy(n => new { 
        Parent = n.ParentNode, 
        Index = n.NextSiblingIsCode() ? idx : idx++ 
    });

foreach (var group in nodes)
{
    var pre = HtmlNode.CreateNode("<pre class='brush: csharp'></pre>");
    pre.AppendChild(doc.CreateTextNode(
        string.Join(Environment.NewLine, group.Select(g => g.InnerText))
    ));
    group.Key.Parent.InsertBefore(pre, group.First());

    foreach (var code in group)
        code.Remove();
}

Here, the grouping field combines a parent node and a group index, which is raised whenever a new group is discovered. I also usedNextSiblingIsCode here's an extension technique

public static bool NextSiblingIsCode(this HtmlNode node)
{
    return (node.NextSibling != null && node.NextSibling.Name == "code") ||
        (node.NextSibling is HtmlTextNode && 
         node.NextSibling.NextSibling != null && 
         node.NextSibling.NextSibling.Name == "code");
}

To ascertain if the following sibling is a<code> node.

The second strategy is to just choose the best<code> cycle over each of these nodes to locate the next node for each group.<code> before the first non-<code> node. I usedxpath here:

var nodes = doc.DocumentNode.SelectNodes(
    "//code[name(preceding-sibling::*[1])!='code']"
);
foreach (var node in nodes)
{
    var pre = HtmlNode.CreateNode("<pre class='brush: csharp'></pre>");
    node.ParentNode.InsertBefore(pre, node);
    var content = string.Empty;
    var next = node;
    do
    {
        content += next.InnerText + Environment.NewLine;
        var previous = next;
        next = next.SelectSingleNode("following-sibling::*[1][name()='code']");
        previous.Remove();
    } while (next != null);
    pre.AppendChild(doc.CreateTextNode(
        content.TrimEnd(Environment.NewLine.ToCharArray())
    ));
}

Html Agility Pack is the best technique to integrate nodes.

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