source: branches/HeuristicLab.Problems.GrammaticalOptimization/DynamicDataDisplay/Common/RingDictionary.cs @ 13401

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Diagnostics.Contracts;

namespace Microsoft.Research.DynamicDataDisplay.Common
{
  /// <summary>
  /// Represents a dictionary with automatic removal of old values.
  /// </summary>
  /// <typeparam name="T"></typeparam>
  public sealed class RingDictionary<T>
  {
    private int startGeneration = 0;
    private int generation;
    private readonly Dictionary<int, T> dict = new Dictionary<int, T>();
    private readonly int maxElements = 5;

    public RingDictionary(int maxElements = 5)
    {
      Contract.Assert(maxElements >= 1);

      this.maxElements = maxElements;
    }

    public int Generation
    {
      get { return generation; }
    }

    public int StartGeneration
    {
      get { return startGeneration; }
    }

    public bool ContainsValue(T value)
    {
      return dict.ContainsValue(value);
    }

    public void AddValue(T value)
    {
      Contract.Assert(value != null);

      dict.Add(generation++, value);
      Cleanup();
    }

    public int Count
    {
      get { return dict.Count; }
    }

    private void Cleanup()
    {
      while ((generation - startGeneration) > maxElements)
      {
        dict.Remove(startGeneration);
        startGeneration++;
      }
    }
  }
}