/Main/src/DynamicDataDisplay/Common/RingDictionary.cs

 1using System;
 2using System.Collections.Generic;
 3using System.Linq;
 4using System.Text;
 5using System.Diagnostics.Contracts;
 6
 7namespace Microsoft.Research.DynamicDataDisplay.Common
 8{
 9	/// <summary>
10	/// Represents a dictionary with automatic removal of old values.
11	/// </summary>
12	/// <typeparam name="T"></typeparam>
13	public sealed class RingDictionary<T>
14	{
15		private int startGeneration = 0;
16		private int generation;
17		private readonly Dictionary<int, T> dict = new Dictionary<int, T>();
18		private readonly int maxElements = 5;
19
20		public RingDictionary(int maxElements = 5)
21		{
22			Contract.Assert(maxElements >= 1);
23
24			this.maxElements = maxElements;
25		}
26
27		public int Generation
28		{
29			get { return generation; }
30		}
31
32		public int StartGeneration
33		{
34			get { return startGeneration; }
35		}
36
37		public bool ContainsValue(T value)
38		{
39			return dict.ContainsValue(value);
40		}
41
42		public void AddValue(T value)
43		{
44			Contract.Assert(value != null);
45
46			dict.Add(generation++, value);
47			Cleanup();
48		}
49
50		public int Count
51		{
52			get { return dict.Count; }
53		}
54
55		private void Cleanup()
56		{
57			while ((generation - startGeneration) > maxElements)
58			{
59				dict.Remove(startGeneration);
60				startGeneration++;
61			}
62		}
63	}
64}