001 /*
002 * Copyright (C) 2007 The Guava Authors
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 * http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017 package com.google.common.collect;
018
019 import static com.google.common.base.Preconditions.checkArgument;
020 import static com.google.common.base.Preconditions.checkNotNull;
021
022 import com.google.common.annotations.GwtCompatible;
023 import com.google.common.annotations.GwtIncompatible;
024
025 import java.io.IOException;
026 import java.io.ObjectInputStream;
027 import java.io.ObjectOutputStream;
028 import java.util.EnumMap;
029 import java.util.Map;
030
031 /**
032 * A {@code BiMap} backed by two {@code EnumMap} instances. Null keys and values
033 * are not permitted. An {@code EnumBiMap} and its inverse are both
034 * serializable.
035 *
036 * <p>See the Guava User Guide article on <a href=
037 * "http://code.google.com/p/guava-libraries/wiki/NewCollectionTypesExplained#BiMap">
038 * {@code BiMap}</a>.
039 *
040 * @author Mike Bostock
041 * @since 2.0 (imported from Google Collections Library)
042 */
043 @GwtCompatible(emulated = true)
044 public final class EnumBiMap<K extends Enum<K>, V extends Enum<V>>
045 extends AbstractBiMap<K, V> {
046 private transient Class<K> keyType;
047 private transient Class<V> valueType;
048
049 /**
050 * Returns a new, empty {@code EnumBiMap} using the specified key and value
051 * types.
052 *
053 * @param keyType the key type
054 * @param valueType the value type
055 */
056 public static <K extends Enum<K>, V extends Enum<V>> EnumBiMap<K, V>
057 create(Class<K> keyType, Class<V> valueType) {
058 return new EnumBiMap<K, V>(keyType, valueType);
059 }
060
061 /**
062 * Returns a new bimap with the same mappings as the specified map. If the
063 * specified map is an {@code EnumBiMap}, the new bimap has the same types as
064 * the provided map. Otherwise, the specified map must contain at least one
065 * mapping, in order to determine the key and value types.
066 *
067 * @param map the map whose mappings are to be placed in this map
068 * @throws IllegalArgumentException if map is not an {@code EnumBiMap}
069 * instance and contains no mappings
070 */
071 public static <K extends Enum<K>, V extends Enum<V>> EnumBiMap<K, V>
072 create(Map<K, V> map) {
073 EnumBiMap<K, V> bimap = create(inferKeyType(map), inferValueType(map));
074 bimap.putAll(map);
075 return bimap;
076 }
077
078 private EnumBiMap(Class<K> keyType, Class<V> valueType) {
079 super(WellBehavedMap.wrap(new EnumMap<K, V>(keyType)),
080 WellBehavedMap.wrap(new EnumMap<V, K>(valueType)));
081 this.keyType = keyType;
082 this.valueType = valueType;
083 }
084
085 static <K extends Enum<K>> Class<K> inferKeyType(Map<K, ?> map) {
086 if (map instanceof EnumBiMap) {
087 return ((EnumBiMap<K, ?>) map).keyType();
088 }
089 if (map instanceof EnumHashBiMap) {
090 return ((EnumHashBiMap<K, ?>) map).keyType();
091 }
092 checkArgument(!map.isEmpty());
093 return map.keySet().iterator().next().getDeclaringClass();
094 }
095
096 private static <V extends Enum<V>> Class<V> inferValueType(Map<?, V> map) {
097 if (map instanceof EnumBiMap) {
098 return ((EnumBiMap<?, V>) map).valueType;
099 }
100 checkArgument(!map.isEmpty());
101 return map.values().iterator().next().getDeclaringClass();
102 }
103
104 /** Returns the associated key type. */
105 public Class<K> keyType() {
106 return keyType;
107 }
108
109 /** Returns the associated value type. */
110 public Class<V> valueType() {
111 return valueType;
112 }
113
114 @Override
115 K checkKey(K key) {
116 return checkNotNull(key);
117 }
118
119 @Override
120 V checkValue(V value) {
121 return checkNotNull(value);
122 }
123
124 /**
125 * @serialData the key class, value class, number of entries, first key, first
126 * value, second key, second value, and so on.
127 */
128 @GwtIncompatible("java.io.ObjectOutputStream")
129 private void writeObject(ObjectOutputStream stream) throws IOException {
130 stream.defaultWriteObject();
131 stream.writeObject(keyType);
132 stream.writeObject(valueType);
133 Serialization.writeMap(this, stream);
134 }
135
136 @SuppressWarnings("unchecked") // reading fields populated by writeObject
137 @GwtIncompatible("java.io.ObjectInputStream")
138 private void readObject(ObjectInputStream stream)
139 throws IOException, ClassNotFoundException {
140 stream.defaultReadObject();
141 keyType = (Class<K>) stream.readObject();
142 valueType = (Class<V>) stream.readObject();
143 setDelegates(
144 WellBehavedMap.wrap(new EnumMap<K, V>(keyType)),
145 WellBehavedMap.wrap(new EnumMap<V, K>(valueType)));
146 Serialization.populateMap(this, stream);
147 }
148
149 @GwtIncompatible("not needed in emulated source.")
150 private static final long serialVersionUID = 0;
151 }