Merging Treenodes

Question

Does anyone know of an algorithm that will merge treenodes in the following way?

treeA
   \\ child a
          \\node(abc)
   \\ child b
          \\node(xyz         


        

Answer 1

If you are using the Node.Name attribute to set the actual path of the item, then a merge is somewhat simple.

First, create a TreeNodeCollection extension like so (this is needed to have a Case Sensitive Find() method for the TreeNodeCollection, which ensures that the Unique Path can be unique by Case as well) :

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace TreeViewApp
{
    public static class TreeNodeCollectionExtensions
    {
        public static TreeNode[] FindExact(this TreeNodeCollection coll, string keytofind)
        {
            TreeNode[] retval;

            if (String.IsNullOrWhiteSpace(keytofind) || coll == null)
            {
                retval = new TreeNode[0];
            }
            else
            {
                TreeNode[] badfinds = coll.Find(keytofind, true);

                List goodfinds = new List();
                foreach (TreeNode bad in badfinds)
                {
                    if (bad.Name == keytofind)
                        goodfinds.Add(bad);
                }
                retval = goodfinds.ToArray();

            }
            return retval;
        }
    }
}

Second, fill a treeview with your Source nodes...
Thrid, fill a treeview with your Target nodes...
Fourth, create an empty treeview.

and then, it's as simple as this:

    private void btn_Merge_Click(object sender, EventArgs e)
    {
        //first merge
        foreach (TreeNode sourceNode in this.treeview_Source.Nodes)
        {
            FindOrAdd(sourceNode, ref this.treeview_Merged);
        }

        //second merge
        foreach (TreeNode targetNode in this.treeview_Target.Nodes)
        {
            FindOrAdd(targetNode, ref this.treeview_Merged);
        }
    }

    private void FindOrAdd(TreeNode FindMe, ref TreeView InHere)
    {
        TreeNode[] found = InHere.Nodes.FindExact(FindMe.Name);
        //if the node is not found, add it at the proper location.
        if (found.Length == 0)
        {
            if (FindMe.Parent != null)
            {
                TreeNode[] foundParent = InHere.Nodes.FindExact(FindMe.Parent.Name);
                if (foundParent.Length == 0)
                    InHere.Nodes.Add((TreeNode)FindMe.Clone());
                else
                    foundParent[0].Nodes.Add((TreeNode)FindMe.Clone());
            }
            else
                InHere.Nodes.Add((TreeNode)FindMe.Clone());
        }
        else
        {
            //if the item was found, check all children.
            foreach (TreeNode child in FindMe.Nodes)
                FindOrAdd(child, ref InHere);
        }
    }

Once again, this solution only works if you have unique paths... with the extension, it also accounts for uniqueness at the case level.

I posted this here in the hopes of helping someone who, like me, had to search for a solution for days on end without success and had to build my own.