co.paralleluniverse.common.util.ConcurrentSet Maven / Gradle / Ivy
/*
* Copyright (c) 2013-2014, Parallel Universe Software Co. All rights reserved.
*
* This program and the accompanying materials are dual-licensed under
* either the terms of the Eclipse Public License v1.0 as published by
* the Eclipse Foundation
*
* or (per the licensee's choosing)
*
* under the terms of the GNU Lesser General Public License version 3.0
* as published by the Free Software Foundation.
*/
package co.paralleluniverse.common.util;
import java.util.AbstractSet;
import java.util.Collection;
import java.util.Iterator;
import java.util.Set;
import java.util.concurrent.ConcurrentMap;
/**
*
* @author pron
*/
public class ConcurrentSet extends AbstractSet implements Set {
public static Set make(ConcurrentMap map) {
return new ConcurrentSet(map);
}
private final ConcurrentMap map;
// Dummy value to associate with an Object in the backing Map
private static final Object PRESENT = new Object();
public ConcurrentSet(ConcurrentMap map) {
this.map = map;
}
public ConcurrentSet(ConcurrentMap map, Collection elements) {
for(E elem : elements)
map.put(elem, PRESENT);
this.map = map;
}
@Override
public boolean add(E e) {
return map.putIfAbsent(e, PRESENT) != PRESENT;
}
@Override
public boolean contains(Object o) {
return map.containsKey(o);
}
@Override
public boolean remove(Object o) {
return map.remove(o) == PRESENT;
}
@Override
public void clear() {
map.clear();
}
@Override
public boolean isEmpty() {
return map.isEmpty();
}
public Iterator iterator() {
return map.keySet().iterator();
}
public int size() {
return map.size();
}
}