IdentityHashSet.java

package arkref.ext.fig.basic;

import java.util.*;

public class IdentityHashSet<E> extends AbstractSet<E> {
  private final Map<E, E> map = new IdentityHashMap();
  public IdentityHashSet() { }
  public IdentityHashSet(Collection<? extends E> c) { for(E o : c) add(o); }
  public int size() { return map.size(); }
  public boolean contains(Object o) { return map.containsKey(o); }
  public Iterator iterator() { return map.keySet().iterator(); }
  public boolean add(E o) { return map.put(o, o) == null; }
  public boolean remove(Object o) { return map.remove(o) != null; }
  public void clear() { map.clear(); }
}