using System;

    using System.Collections.Generic;

    public class Program

    {

        public class IndexedTree {

            private readonly IDictionary<string, IndexedTree> _me;

            private object _value;

            private readonly string _splitKey = ".";

            public IndexedTree this[string key] {

                get {

                    return _me[key];

                }

            }

            public object Value { get; set; }

            public void Add(string dottedItem) {

                if ( string.IsNullOrWhiteSpace( dottedItem ) ) {

                    throw new ArgumentException("dottedItem cannot be empty");

                }

                int index;

                if ( (index = dottedItem.IndexOf( _splitKey ) ) < 0 ) {

                    throw new ArgumentException("dottedItem didn't contain " + _splitKey);

                }

                string key = dottedItem.Substring(0, index), rest = dottedItem.Substring(index + 1);

                IndexedTree child;

                if (_me.ContainsKey(key)) {

                    child = _me[key];

                } else {

                    child = new IndexedTree( _splitKey );

                    _me.Add(key, child);

                }

                if (rest.IndexOf(_splitKey) >= 0) {

                    child.Add(rest);

                } else {

                    // maybe it can be checked if there is already a value set here or not

                    // in case there is a warning or error might be more appropriate

                    child.Value = rest;

                }

            }

            public IndexedTree(string splitKey) {

                _splitKey = splitKey;

                _me = new Dictionary<string, IndexedTree>();

            }

        }

        public static void Main()

        {

            IndexedTree tree = new IndexedTree(".");

            tree.Add("Level1.Level2.Level3.Item");

            tree.Add("Level1.Level2.Value");

            Console.WriteLine(tree["Level1"]["Level2"].Value);

            Console.WriteLine(tree["Level1"]["Level2"]["Level3"].Value);

        }

    }