namespace OxyPlot.WindowsForms {

  using System;

  using System.Collections.Generic;

  using System.Text;

  public class HashSet<T> {

    private readonly Dictionary<T, object> set = new Dictionary<T, object>();

    public bool Add(T value) {

      if (set.ContainsKey(value))

        return true;

      set.Add(value, null);

      return false;

    }

    public bool Contains(T value) {

      return set.ContainsKey(value);

    }

    public void Clear() {

      set.Clear();

    }

  }

}