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();
    }
  }
}