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1   /*
2    * Copyright 2012 The Netty Project
3    *
4    * The Netty Project licenses this file to you under the Apache License,
5    * version 2.0 (the "License"); you may not use this file except in compliance
6    * with the License. You may obtain a copy of the License at:
7    *
8    *   http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
12   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
13   * License for the specific language governing permissions and limitations
14   * under the License.
15   */
16  package org.jboss.netty.handler.codec.serialization;
17  
18  import java.lang.ref.Reference;
19  import java.util.Collection;
20  import java.util.Map;
21  import java.util.Set;
22  
23  abstract class ReferenceMap<K, V> implements Map<K, V> {
24  
25      private final Map<K, Reference<V>> delegate;
26  
27      protected ReferenceMap(Map<K, Reference<V>> delegate) {
28          this.delegate = delegate;
29      }
30  
31      abstract Reference<V> fold(V value);
32  
33      private V unfold(Reference<V> ref) {
34          if (ref == null) {
35              return null;
36          }
37  
38          return ref.get();
39      }
40  
41      public int size() {
42          return delegate.size();
43      }
44  
45      public boolean isEmpty() {
46          return delegate.isEmpty();
47      }
48  
49      public boolean containsKey(Object key) {
50          return delegate.containsKey(key);
51      }
52  
53      public boolean containsValue(Object value) {
54          throw new UnsupportedOperationException();
55      }
56  
57      public V get(Object key) {
58          return unfold(delegate.get(key));
59      }
60  
61      public V put(K key, V value) {
62          return unfold(delegate.put(key, fold(value)));
63      }
64  
65      public V remove(Object key) {
66          return unfold(delegate.remove(key));
67      }
68  
69      public void putAll(Map<? extends K, ? extends V> m) {
70          for (Entry<? extends K, ? extends V> entry : m.entrySet()) {
71              delegate.put(entry.getKey(), fold(entry.getValue()));
72          }
73      }
74  
75      public void clear() {
76          delegate.clear();
77      }
78  
79      public Set<K> keySet() {
80          return delegate.keySet();
81      }
82  
83      public Collection<V> values() {
84          throw new UnsupportedOperationException();
85      }
86  
87      public Set<Entry<K, V>> entrySet() {
88          throw new UnsupportedOperationException();
89      }
90  }