    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    }