Simple tree data structure for use with C# and Unity. Start with a root TreeNode and add children as required.

TreeNode.cs

/**
 * TreeNode.cs
 * Author: Luke Holland (http://lukeholland.me/)
 */

using System;
using System.Collections.Generic;

public class TreeNode<T>
{

	public delegate bool TraversalDataDelegate(T data);
	public delegate bool TraversalNodeDelegate(TreeNode<T> node);

	private readonly T _data;
	private readonly TreeNode<T> _parent;
	private readonly int _level;
	private readonly List<TreeNode<T>> _children;

	public TreeNode(T data)
	{
		_data = data;
		_children = new List<TreeNode<T>>();
		_level = 0;
	}

	public TreeNode(T data, TreeNode<T> parent) : this(data)
	{
		_parent = parent;
		_level = _parent!=null ? _parent.Level+1 : 0;
	}

	public int Level { get { return _level; } }
	public int Count { get { return _children.Count; }}
	public bool IsRoot { get { return _parent==null; }}
	public bool IsLeaf { get { return _children.Count==0; }}
	public T Data { get { return _data; }}
	public TreeNode<T> Parent { get { return _parent; }}

	public TreeNode<T> this[int key]
	{
		get { return _children[key]; }
	}

	public void Clear()
	{
		_children.Clear();
	}

	public TreeNode<T> AddChild(T value)
	{
		TreeNode<T> node = new TreeNode<T>(value,this);
		_children.Add(node);

		return node;
	}

	public bool HasChild(T data)
	{
		return FindInChildren(data)!=null;
	}

	public TreeNode<T> FindInChildren(T data)
	{
		int i = 0, l = Count;
		for(; i<l; ++i){
			TreeNode<T> child = _children[i];
			if(child.Data.Equals(data)) return child;
		}

		return null;
	}

	public bool RemoveChild(TreeNode<T> node)
	{
		return _children.Remove(node);
	}

	public void Traverse(TraversalDataDelegate handler)
	{
		if(handler(_data)){
			int i = 0, l = Count;
			for(; i<l; ++i) _children[i].Traverse(handler);
		}
	}

	public void Traverse(TraversalNodeDelegate handler)
	{
		if(handler(this)){
			int i = 0, l = Count;
			for(; i<l; ++i) _children[i].Traverse(handler);
		}
	}

}