1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one
3 * or more contributor license agreements. See the NOTICE file
4 * distributed with this work for additional information
5 * regarding copyright ownership. The ASF licenses this file
6 * to you under the Apache License, Version 2.0 (the
7 * "License"); you may not use this file except in compliance
8 * with the License. You may obtain a copy of the License at
9 *
10 * http://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing,
13 * software distributed under the License is distributed on an
14 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15 * KIND, either express or implied. See the License for the
16 * specific language governing permissions and limitations
17 * under the License.
18 *
19 */
20 package org.apache.mina.util;
21
22 import java.io.Serializable;
23 import java.util.AbstractSet;
24 import java.util.Collection;
25 import java.util.Iterator;
26 import java.util.Map;
27 import java.util.Set;
28
29 /**
30 * A {@link Map}-backed {@link Set}.
31 *
32 * @author The Apache MINA Project (dev@mina.apache.org)
33 * @version $Rev: 597692 $, $Date: 2007-11-23 16:56:32 +0100 (ven, 23 nov 2007) $
34 */
35 public class MapBackedSet<E> extends AbstractSet<E> implements Serializable {
36
37 private static final long serialVersionUID = -8347878570391674042L;
38
39 protected final Map<E, Boolean> map;
40
41 public MapBackedSet(Map<E, Boolean> map) {
42 this.map = map;
43 }
44
45 public MapBackedSet(Map<E, Boolean> map, Collection<E> c) {
46 this.map = map;
47 addAll(c);
48 }
49
50 @Override
51 public int size() {
52 return map.size();
53 }
54
55 @Override
56 public boolean contains(Object o) {
57 return map.containsKey(o);
58 }
59
60 @Override
61 public Iterator<E> iterator() {
62 return map.keySet().iterator();
63 }
64
65 @Override
66 public boolean add(E o) {
67 return map.put(o, Boolean.TRUE) == null;
68 }
69
70 @Override
71 public boolean remove(Object o) {
72 return map.remove(o) != null;
73 }
74
75 @Override
76 public void clear() {
77 map.clear();
78 }
79 }