1/*
2 * Copyright (C) 2007 The Guava Authors
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * 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,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package com.google.common.collect;
18
19import static com.google.common.base.Preconditions.checkArgument;
20import static com.google.common.base.Preconditions.checkNotNull;
21
22import com.google.common.annotations.GwtCompatible;
23
24import java.util.EnumMap;
25import java.util.Map;
26
27/**
28 * A {@code BiMap} backed by two {@code EnumMap} instances. Null keys and values
29 * are not permitted. An {@code EnumBiMap} and its inverse are both
30 * serializable.
31 *
32 * <p>See the Guava User Guide article on <a href=
33 * "http://code.google.com/p/guava-libraries/wiki/NewCollectionTypesExplained#BiMap">
34 * {@code BiMap}</a>.
35 *
36 * @author Mike Bostock
37 * @since 2.0 (imported from Google Collections Library)
38 */
39@GwtCompatible(emulated = true)
40public final class EnumBiMap<K extends Enum<K>, V extends Enum<V>>
41    extends AbstractBiMap<K, V> {
42  private transient Class<K> keyType;
43  private transient Class<V> valueType;
44
45  /**
46   * Returns a new, empty {@code EnumBiMap} using the specified key and value
47   * types.
48   *
49   * @param keyType the key type
50   * @param valueType the value type
51   */
52  public static <K extends Enum<K>, V extends Enum<V>> EnumBiMap<K, V>
53      create(Class<K> keyType, Class<V> valueType) {
54    return new EnumBiMap<K, V>(keyType, valueType);
55  }
56
57  /**
58   * Returns a new bimap with the same mappings as the specified map. If the
59   * specified map is an {@code EnumBiMap}, the new bimap has the same types as
60   * the provided map. Otherwise, the specified map must contain at least one
61   * mapping, in order to determine the key and value types.
62   *
63   * @param map the map whose mappings are to be placed in this map
64   * @throws IllegalArgumentException if map is not an {@code EnumBiMap}
65   *     instance and contains no mappings
66   */
67  public static <K extends Enum<K>, V extends Enum<V>> EnumBiMap<K, V>
68      create(Map<K, V> map) {
69    EnumBiMap<K, V> bimap = create(inferKeyType(map), inferValueType(map));
70    bimap.putAll(map);
71    return bimap;
72  }
73
74  private EnumBiMap(Class<K> keyType, Class<V> valueType) {
75    super(WellBehavedMap.wrap(new EnumMap<K, V>(keyType)),
76        WellBehavedMap.wrap(new EnumMap<V, K>(valueType)));
77    this.keyType = keyType;
78    this.valueType = valueType;
79  }
80
81  static <K extends Enum<K>> Class<K> inferKeyType(Map<K, ?> map) {
82    if (map instanceof EnumBiMap) {
83      return ((EnumBiMap<K, ?>) map).keyType();
84    }
85    if (map instanceof EnumHashBiMap) {
86      return ((EnumHashBiMap<K, ?>) map).keyType();
87    }
88    checkArgument(!map.isEmpty());
89    return map.keySet().iterator().next().getDeclaringClass();
90  }
91
92  private static <V extends Enum<V>> Class<V> inferValueType(Map<?, V> map) {
93    if (map instanceof EnumBiMap) {
94      return ((EnumBiMap<?, V>) map).valueType;
95    }
96    checkArgument(!map.isEmpty());
97    return map.values().iterator().next().getDeclaringClass();
98  }
99
100  /** Returns the associated key type. */
101  public Class<K> keyType() {
102    return keyType;
103  }
104
105  /** Returns the associated value type. */
106  public Class<V> valueType() {
107    return valueType;
108  }
109
110  @Override
111  K checkKey(K key) {
112    return checkNotNull(key);
113  }
114
115  @Override
116  V checkValue(V value) {
117    return checkNotNull(value);
118  }
119}
120
121