using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Collections;

using System.Diagnostics;



namespace Microsoft.Research.DynamicDataDisplay.Charts.Maps

{

	/// <summary>

	/// Represents an unordered set of values.

	/// </summary>

	/// <typeparam name="T">Type of values.</typeparam>

	[DebuggerDisplay("Count = {Count}")]

	public sealed class Set<T> : IEnumerable<T>

	{

		private readonly Dictionary<T, Dummy> cache = new Dictionary<T, Dummy>();



		public void Add(T item)

		{

			cache.Add(item, Dummy.Instance);

		}



		public bool TryAdd(T item)

		{

			if (!Contains(item))

			{

				Add(item);

				return true;

			}



			return false;

		}



		public bool Remove(T item)

		{

			bool contains = cache.ContainsKey(item);

			bool result = cache.Remove(item);



			if (contains)

			{

				Debug.Assert(!cache.ContainsKey(item));

			}

			return result;

		}



		public bool Contains(T item)

		{

			return cache.ContainsKey(item);

		}



		private class Dummy

		{

			public static readonly Dummy Instance = new Dummy();

		}



		#region IEnumerable<T> Members



		public IEnumerator<T> GetEnumerator()

		{

			return cache.Keys.GetEnumerator();

		}



		#endregion



		#region IEnumerable Members



		IEnumerator IEnumerable.GetEnumerator()

		{

			return GetEnumerator();

		}



		#endregion



		public void Clear()

		{

			cache.Clear();

		}



		public int Count

		{

			get { return cache.Count; }

		}

	}

}