summaryrefslogtreecommitdiffstats
path: root/guava/src/com/google/common/collect/EnumBiMap.java
blob: 05d84ed352f227039d814c38aaf819f7fb84bade (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
/*
 * Copyright (C) 2007 The Guava Authors
 *
 * 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 com.google.common.collect;

import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;

import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;

import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.EnumMap;
import java.util.Map;

/**
 * A {@code BiMap} backed by two {@code EnumMap} instances. Null keys and values
 * are not permitted. An {@code EnumBiMap} and its inverse are both
 * serializable.
 * 
 * <p>See the Guava User Guide article on <a href=
 * "http://code.google.com/p/guava-libraries/wiki/NewCollectionTypesExplained#BiMap">
 * {@code BiMap}</a>.
 *
 * @author Mike Bostock
 * @since 2.0 (imported from Google Collections Library)
 */
@GwtCompatible(emulated = true)
public final class EnumBiMap<K extends Enum<K>, V extends Enum<V>>
    extends AbstractBiMap<K, V> {
  private transient Class<K> keyType;
  private transient Class<V> valueType;

  /**
   * Returns a new, empty {@code EnumBiMap} using the specified key and value
   * types.
   *
   * @param keyType the key type
   * @param valueType the value type
   */
  public static <K extends Enum<K>, V extends Enum<V>> EnumBiMap<K, V>
      create(Class<K> keyType, Class<V> valueType) {
    return new EnumBiMap<K, V>(keyType, valueType);
  }

  /**
   * Returns a new bimap with the same mappings as the specified map. If the
   * specified map is an {@code EnumBiMap}, the new bimap has the same types as
   * the provided map. Otherwise, the specified map must contain at least one
   * mapping, in order to determine the key and value types.
   *
   * @param map the map whose mappings are to be placed in this map
   * @throws IllegalArgumentException if map is not an {@code EnumBiMap}
   *     instance and contains no mappings
   */
  public static <K extends Enum<K>, V extends Enum<V>> EnumBiMap<K, V>
      create(Map<K, V> map) {
    EnumBiMap<K, V> bimap = create(inferKeyType(map), inferValueType(map));
    bimap.putAll(map);
    return bimap;
  }

  private EnumBiMap(Class<K> keyType, Class<V> valueType) {
    super(WellBehavedMap.wrap(new EnumMap<K, V>(keyType)),
        WellBehavedMap.wrap(new EnumMap<V, K>(valueType)));
    this.keyType = keyType;
    this.valueType = valueType;
  }

  static <K extends Enum<K>> Class<K> inferKeyType(Map<K, ?> map) {
    if (map instanceof EnumBiMap) {
      return ((EnumBiMap<K, ?>) map).keyType();
    }
    if (map instanceof EnumHashBiMap) {
      return ((EnumHashBiMap<K, ?>) map).keyType();
    }
    checkArgument(!map.isEmpty());
    return map.keySet().iterator().next().getDeclaringClass();
  }

  private static <V extends Enum<V>> Class<V> inferValueType(Map<?, V> map) {
    if (map instanceof EnumBiMap) {
      return ((EnumBiMap<?, V>) map).valueType;
    }
    checkArgument(!map.isEmpty());
    return map.values().iterator().next().getDeclaringClass();
  }

  /** Returns the associated key type. */
  public Class<K> keyType() {
    return keyType;
  }

  /** Returns the associated value type. */
  public Class<V> valueType() {
    return valueType;
  }

  @Override
  K checkKey(K key) {
    return checkNotNull(key);
  }

  @Override
  V checkValue(V value) {
    return checkNotNull(value);
  }

  /**
   * @serialData the key class, value class, number of entries, first key, first
   *     value, second key, second value, and so on.
   */
  @GwtIncompatible("java.io.ObjectOutputStream")
  private void writeObject(ObjectOutputStream stream) throws IOException {
    stream.defaultWriteObject();
    stream.writeObject(keyType);
    stream.writeObject(valueType);
    Serialization.writeMap(this, stream);
  }

  @SuppressWarnings("unchecked") // reading fields populated by writeObject
  @GwtIncompatible("java.io.ObjectInputStream")
  private void readObject(ObjectInputStream stream)
      throws IOException, ClassNotFoundException {
    stream.defaultReadObject();
    keyType = (Class<K>) stream.readObject();
    valueType = (Class<V>) stream.readObject();
    setDelegates(
        WellBehavedMap.wrap(new EnumMap<K, V>(keyType)),
        WellBehavedMap.wrap(new EnumMap<V, K>(valueType)));
    Serialization.populateMap(this, stream);
  }

  @GwtIncompatible("not needed in emulated source.")
  private static final long serialVersionUID = 0;
}