001 /*
002 * Copyright (C) 2007 Google Inc.
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
021 import com.google.common.annotations.GwtCompatible;
022 import com.google.common.annotations.GwtIncompatible;
023
024 import java.io.IOException;
025 import java.io.ObjectInputStream;
026 import java.io.ObjectOutputStream;
027 import java.util.EnumMap;
028 import java.util.Map;
029
030 /**
031 * A {@code BiMap} backed by two {@code EnumMap} instances. Null keys and values
032 * are not permitted. An {@code EnumBiMap} and its inverse are both
033 * serializable.
034 *
035 * @author Mike Bostock
036 * @since 2 (imported from Google Collections Library)
037 */
038 @GwtCompatible(emulated = true)
039 public final class EnumBiMap<K extends Enum<K>, V extends Enum<V>>
040 extends AbstractBiMap<K, V> {
041 private transient Class<K> keyType;
042 private transient Class<V> valueType;
043
044 /**
045 * Returns a new, empty {@code EnumBiMap} using the specified key and value
046 * types.
047 *
048 * @param keyType the key type
049 * @param valueType the value type
050 */
051 public static <K extends Enum<K>, V extends Enum<V>> EnumBiMap<K, V>
052 create(Class<K> keyType, Class<V> valueType) {
053 return new EnumBiMap<K, V>(keyType, valueType);
054 }
055
056 /**
057 * Returns a new bimap with the same mappings as the specified map. If the
058 * specified map is an {@code EnumBiMap}, the new bimap has the same types as
059 * the provided map. Otherwise, the specified map must contain at least one
060 * mapping, in order to determine the key and value types.
061 *
062 * @param map the map whose mappings are to be placed in this map
063 * @throws IllegalArgumentException if map is not an {@code EnumBiMap}
064 * instance and contains no mappings
065 */
066 public static <K extends Enum<K>, V extends Enum<V>> EnumBiMap<K, V>
067 create(Map<K, V> map) {
068 EnumBiMap<K, V> bimap = create(inferKeyType(map), inferValueType(map));
069 bimap.putAll(map);
070 return bimap;
071 }
072
073 private EnumBiMap(Class<K> keyType, Class<V> valueType) {
074 super(new EnumMap<K, V>(keyType), new EnumMap<V, K>(valueType));
075 this.keyType = keyType;
076 this.valueType = valueType;
077 }
078
079 static <K extends Enum<K>> Class<K> inferKeyType(Map<K, ?> map) {
080 if (map instanceof EnumBiMap) {
081 return ((EnumBiMap<K, ?>) map).keyType();
082 }
083 if (map instanceof EnumHashBiMap) {
084 return ((EnumHashBiMap<K, ?>) map).keyType();
085 }
086 checkArgument(!map.isEmpty());
087 return map.keySet().iterator().next().getDeclaringClass();
088 }
089
090 private static <V extends Enum<V>> Class<V> inferValueType(Map<?, V> map) {
091 if (map instanceof EnumBiMap) {
092 return ((EnumBiMap<?, V>) map).valueType;
093 }
094 checkArgument(!map.isEmpty());
095 return map.values().iterator().next().getDeclaringClass();
096 }
097
098 /** Returns the associated key type. */
099 public Class<K> keyType() {
100 return keyType;
101 }
102
103 /** Returns the associated value type. */
104 public Class<V> valueType() {
105 return valueType;
106 }
107
108 /**
109 * @serialData the key class, value class, number of entries, first key, first
110 * value, second key, second value, and so on.
111 */
112 @GwtIncompatible("java.io.ObjectOutputStream")
113 private void writeObject(ObjectOutputStream stream) throws IOException {
114 stream.defaultWriteObject();
115 stream.writeObject(keyType);
116 stream.writeObject(valueType);
117 Serialization.writeMap(this, stream);
118 }
119
120 @SuppressWarnings("unchecked") // reading fields populated by writeObject
121 @GwtIncompatible("java.io.ObjectInputStream")
122 private void readObject(ObjectInputStream stream)
123 throws IOException, ClassNotFoundException {
124 stream.defaultReadObject();
125 keyType = (Class<K>) stream.readObject();
126 valueType = (Class<V>) stream.readObject();
127 setDelegates(new EnumMap<K, V>(keyType), new EnumMap<V, K>(valueType));
128 Serialization.populateMap(this, stream);
129 }
130
131 @GwtIncompatible("not needed in emulated source.")
132 private static final long serialVersionUID = 0;
133 }