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package com.google.code.yanf4j.util;

import java.io.Serializable;
import java.util.AbstractSet;
import java.util.Collection;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

/**
 * A {@link Map}-backed {@link Set}.
 * 
 * @author The Apache MINA Project ([email protected])
 * @version $Rev: 597692 $, $Date: 2007-11-23 08:56:32 -0700 (Fri, 23 Nov 2007) $
 */
public class MapBackedSet extends AbstractSet implements Serializable {

  private static final long serialVersionUID = -8347878570391674042L;

  protected final Map map;

  public MapBackedSet(Map map) {
    this.map = map;
  }

  public MapBackedSet(Map map, Collection c) {
    this.map = map;
    addAll(c);
  }

  @Override
  public int size() {
    return map.size();
  }

  @Override
  public boolean contains(Object o) {
    return map.containsKey(o);
  }

  @Override
  public Iterator iterator() {
    return map.keySet().iterator();
  }

  @Override
  public boolean add(E o) {
    return map.put(o, Boolean.TRUE) == null;
  }

  @Override
  public boolean remove(Object o) {
    return map.remove(o) != null;
  }

  @Override
  public void clear() {
    map.clear();
  }
}