View Javadoc
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 io.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      @Override
42      public int size() {
43          return delegate.size();
44      }
45  
46      @Override
47      public boolean isEmpty() {
48          return delegate.isEmpty();
49      }
50  
51      @Override
52      public boolean containsKey(Object key) {
53          return delegate.containsKey(key);
54      }
55  
56      @Override
57      public boolean containsValue(Object value) {
58          throw new UnsupportedOperationException();
59      }
60  
61      @Override
62      public V get(Object key) {
63          return unfold(delegate.get(key));
64      }
65  
66      @Override
67      public V put(K key, V value) {
68          return unfold(delegate.put(key, fold(value)));
69      }
70  
71      @Override
72      public V remove(Object key) {
73          return unfold(delegate.remove(key));
74      }
75  
76      @Override
77      public void putAll(Map<? extends K, ? extends V> m) {
78          for (Entry<? extends K, ? extends V> entry : m.entrySet()) {
79              delegate.put(entry.getKey(), fold(entry.getValue()));
80          }
81      }
82  
83      @Override
84      public void clear() {
85          delegate.clear();
86      }
87  
88      @Override
89      public Set<K> keySet() {
90          return delegate.keySet();
91      }
92  
93      @Override
94      public Collection<V> values() {
95          throw new UnsupportedOperationException();
96      }
97  
98      @Override
99      public Set<Entry<K, V>> entrySet() {
100         throw new UnsupportedOperationException();
101     }
102 }