MultiValue Dictionary

/*
 *
 *  http://csharpcodewhisperer.blogspot.com
 *
 * Made using SharpDevelop
 *
 */

using System;
using System.Collections.Generic;

namespace MultiValueDictionary
{
    public class MultiValueDictionary<K,V>
    {
        Dictionary<K, List<V>> _dictionary = new Dictionary<K, List<V>>();

        public void Add(K key, V value)
        {
            List<V> list;
            if (this._dictionary.TryGetValue(key, out list))
            {
                list.Add(value);
            }
            else
            {
                list = new List<V>();
                list.Add(value);
                this._dictionary[key] = list;
            }
        }

        public int Count
        {
            get { return this._dictionary.Count; }
        }

        public IEnumerable<K> Keys
        {
            get
            {
                return this._dictionary.Keys;
            }
        }

        public IEnumerable<List<V>> Values
        {
            get {   return this._dictionary.Values; }
        }

        public List<V> this[K key]
        {
            get
            {
                List<V> list;
                if (!this._dictionary.TryGetValue(key, out list))
                {
                    list = new List<V>();
                    this._dictionary[key] = list;
                }
                return list;
            }
        }
    }
}