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;
024
025import java.io.IOException;
026import java.io.ObjectInputStream;
027import java.io.ObjectOutputStream;
028import java.util.EnumMap;
029import 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)
044public 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}