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 017package com.google.common.collect; 018 019import static com.google.common.base.Preconditions.checkArgument; 020import static com.google.common.base.Preconditions.checkNotNull; 021 022import com.google.common.annotations.GwtCompatible; 023import com.google.common.annotations.GwtIncompatible; 024import java.io.IOException; 025import java.io.ObjectInputStream; 026import java.io.ObjectOutputStream; 027import java.util.EnumMap; 028import java.util.Map; 029 030/** 031 * A {@code BiMap} backed by two {@code EnumMap} instances. Null keys and values are not permitted. 032 * An {@code EnumBiMap} and its inverse are both serializable. 033 * 034 * <p>See the Guava User Guide article on <a href= 035 * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#bimap"> {@code BiMap}</a>. 036 * 037 * @author Mike Bostock 038 * @since 2.0 039 */ 040@GwtCompatible(emulated = true) 041public final class EnumBiMap<K extends Enum<K>, V extends Enum<V>> extends AbstractBiMap<K, V> { 042 private transient Class<K> keyType; 043 private transient Class<V> valueType; 044 045 /** 046 * Returns a new, empty {@code EnumBiMap} using the specified key and value 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> create( 052 Class<K> keyType, Class<V> valueType) { 053 return new EnumBiMap<>(keyType, valueType); 054 } 055 056 /** 057 * Returns a new bimap with the same mappings as the specified map. If the specified map is an 058 * {@code EnumBiMap}, the new bimap has the same types as the provided map. Otherwise, the 059 * specified map must contain at least one mapping, in order to determine the key and value types. 060 * 061 * @param map the map whose mappings are to be placed in this map 062 * @throws IllegalArgumentException if map is not an {@code EnumBiMap} instance and contains no 063 * mappings 064 */ 065 public static <K extends Enum<K>, V extends Enum<V>> EnumBiMap<K, V> create(Map<K, V> map) { 066 EnumBiMap<K, V> bimap = create(inferKeyType(map), inferValueType(map)); 067 bimap.putAll(map); 068 return bimap; 069 } 070 071 private EnumBiMap(Class<K> keyType, Class<V> valueType) { 072 super(new EnumMap<K, V>(keyType), new EnumMap<V, K>(valueType)); 073 this.keyType = keyType; 074 this.valueType = valueType; 075 } 076 077 static <K extends Enum<K>> Class<K> inferKeyType(Map<K, ?> map) { 078 if (map instanceof EnumBiMap) { 079 return ((EnumBiMap<K, ?>) map).keyType(); 080 } 081 if (map instanceof EnumHashBiMap) { 082 return ((EnumHashBiMap<K, ?>) map).keyType(); 083 } 084 checkArgument(!map.isEmpty()); 085 return map.keySet().iterator().next().getDeclaringClass(); 086 } 087 088 private static <V extends Enum<V>> Class<V> inferValueType(Map<?, V> map) { 089 if (map instanceof EnumBiMap) { 090 return ((EnumBiMap<?, V>) map).valueType; 091 } 092 checkArgument(!map.isEmpty()); 093 return map.values().iterator().next().getDeclaringClass(); 094 } 095 096 /** Returns the associated key type. */ 097 public Class<K> keyType() { 098 return keyType; 099 } 100 101 /** Returns the associated value type. */ 102 public Class<V> valueType() { 103 return valueType; 104 } 105 106 @Override 107 K checkKey(K key) { 108 return checkNotNull(key); 109 } 110 111 @Override 112 V checkValue(V value) { 113 return checkNotNull(value); 114 } 115 116 /** 117 * @serialData the key class, value class, number of entries, first key, first value, second key, 118 * second value, and so on. 119 */ 120 @GwtIncompatible // java.io.ObjectOutputStream 121 private void writeObject(ObjectOutputStream stream) throws IOException { 122 stream.defaultWriteObject(); 123 stream.writeObject(keyType); 124 stream.writeObject(valueType); 125 Serialization.writeMap(this, stream); 126 } 127 128 @SuppressWarnings("unchecked") // reading fields populated by writeObject 129 @GwtIncompatible // java.io.ObjectInputStream 130 private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException { 131 stream.defaultReadObject(); 132 keyType = (Class<K>) stream.readObject(); 133 valueType = (Class<V>) stream.readObject(); 134 setDelegates(new EnumMap<K, V>(keyType), new EnumMap<V, K>(valueType)); 135 Serialization.populateMap(this, stream); 136 } 137 138 @GwtIncompatible // not needed in emulated source. 139 private static final long serialVersionUID = 0; 140}