- /*
- * Copyright 2004 The Apache Software Foundation
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
- package org.apache.commons.collections.set;
-
- import java.io.Serializable;
- import java.util.Collection;
- import java.util.Iterator;
- import java.util.Map;
- import java.util.Set;
-
- /**
- * Decorates a <code>Map</code> to obtain <code>Set</code> behaviour.
- * <p>
- * This class is used to create a <code>Set</code> with the same properties as
- * the key set of any map. Thus, a ReferenceSet can be created by wrapping a
- * <code>ReferenceMap</code> in an instance of this class.
- * <p>
- * Most map implementation can be used to create a set by passing in dummy values.
- * Exceptions include <code>BidiMap</code> implementations, as they require unique values.
- *
- * @since Commons Collections 3.1
- * @version $Revision: 1.2 $ $Date: 2004/06/02 22:00:47 $
- *
- * @author Stephen Colebourne
- */
- public final class MapBackedSet implements Set, Serializable {
-
- /** Serialization version */
- private static final long serialVersionUID = 6723912213766056587L;
-
- /** The map being used as the backing store */
- protected final Map map;
- /** The dummyValue to use */
- protected final Object dummyValue;
-
- /**
- * Factory method to create a set from a map.
- *
- * @param map the map to decorate, must not be null
- * @throws IllegalArgumentException if set is null
- */
- public static Set decorate(Map map) {
- return decorate(map, null);
- }
-
- /**
- * Factory method to create a set from a map.
- *
- * @param map the map to decorate, must not be null
- * @param dummyValue the dummy value to use
- * @throws IllegalArgumentException if map is null
- */
- public static Set decorate(Map map, Object dummyValue) {
- if (map == null) {
- throw new IllegalArgumentException("The map must not be null");
- }
- return new MapBackedSet(map, dummyValue);
- }
-
- //-----------------------------------------------------------------------
- /**
- * Constructor that wraps (not copies).
- *
- * @param map the map to decorate, must not be null
- * @param dummyValue the dummy value to use
- * @throws IllegalArgumentException if map is null
- */
- private MapBackedSet(Map map, Object dummyValue) {
- super();
- this.map = map;
- this.dummyValue = dummyValue;
- }
-
- //-----------------------------------------------------------------------
- public int size() {
- return map.size();
- }
-
- public boolean isEmpty() {
- return map.isEmpty();
- }
-
- public Iterator iterator() {
- return map.keySet().iterator();
- }
-
- public boolean contains(Object obj) {
- return map.containsKey(obj);
- }
-
- public boolean containsAll(Collection coll) {
- return map.keySet().containsAll(coll);
- }
-
- public boolean add(Object obj) {
- int size = map.size();
- map.put(obj, dummyValue);
- return (map.size() != size);
- }
-
- public boolean addAll(Collection coll) {
- int size = map.size();
- for (Iterator it = coll.iterator(); it.hasNext();) {
- Object obj = (Object) it.next();
- map.put(obj, dummyValue);
- }
- return (map.size() != size);
- }
-
- public boolean remove(Object obj) {
- int size = map.size();
- map.remove(obj);
- return (map.size() != size);
- }
-
- public boolean removeAll(Collection coll) {
- return map.keySet().removeAll(coll);
- }
-
- public boolean retainAll(Collection coll) {
- return map.keySet().retainAll(coll);
- }
-
- public void clear() {
- map.clear();
- }
-
- public Object[] toArray() {
- return map.keySet().toArray();
- }
-
- public Object[] toArray(Object[] array) {
- return map.keySet().toArray(array);
- }
-
- public boolean equals(Object obj) {
- return map.keySet().equals(obj);
- }
-
- public int hashCode() {
- return map.keySet().hashCode();
- }
-
- }