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
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 2.0 (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(WellBehavedMap.wrap(new EnumMap<K, V>(keyType)),
075 WellBehavedMap.wrap(new EnumMap<V, K>(valueType)));
076 this.keyType = keyType;
077 this.valueType = valueType;
078 }
079
080 static <K extends Enum<K>> Class<K> inferKeyType(Map<K, ?> map) {
081 if (map instanceof EnumBiMap) {
082 return ((EnumBiMap<K, ?>) map).keyType();
083 }
084 if (map instanceof EnumHashBiMap) {
085 return ((EnumHashBiMap<K, ?>) map).keyType();
086 }
087 checkArgument(!map.isEmpty());
088 return map.keySet().iterator().next().getDeclaringClass();
089 }
090
091 private static <V extends Enum<V>> Class<V> inferValueType(Map<?, V> map) {
092 if (map instanceof EnumBiMap) {
093 return ((EnumBiMap<?, V>) map).valueType;
094 }
095 checkArgument(!map.isEmpty());
096 return map.values().iterator().next().getDeclaringClass();
097 }
098
099 /** Returns the associated key type. */
100 public Class<K> keyType() {
101 return keyType;
102 }
103
104 /** Returns the associated value type. */
105 public Class<V> valueType() {
106 return valueType;
107 }
108
109 /**
110 * @serialData the key class, value class, number of entries, first key, first
111 * value, second key, second value, and so on.
112 */
113 @GwtIncompatible("java.io.ObjectOutputStream")
114 private void writeObject(ObjectOutputStream stream) throws IOException {
115 stream.defaultWriteObject();
116 stream.writeObject(keyType);
117 stream.writeObject(valueType);
118 Serialization.writeMap(this, stream);
119 }
120
121 @SuppressWarnings("unchecked") // reading fields populated by writeObject
122 @GwtIncompatible("java.io.ObjectInputStream")
123 private void readObject(ObjectInputStream stream)
124 throws IOException, ClassNotFoundException {
125 stream.defaultReadObject();
126 keyType = (Class<K>) stream.readObject();
127 valueType = (Class<V>) stream.readObject();
128 setDelegates(
129 WellBehavedMap.wrap(new EnumMap<K, V>(keyType)),
130 WellBehavedMap.wrap(new EnumMap<V, K>(valueType)));
131 Serialization.populateMap(this, stream);
132 }
133
134 @GwtIncompatible("not needed in emulated source.")
135 private static final long serialVersionUID = 0;
136 }