129 lines
4.2 KiB
Java
129 lines
4.2 KiB
Java
/*
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* Copyright (C) 2007 The Guava Authors
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.google.common.collect;
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import static com.google.common.base.Preconditions.checkNotNull;
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import java.io.IOException;
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import java.io.ObjectInputStream;
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import java.io.ObjectOutputStream;
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import java.util.EnumMap;
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import java.util.HashMap;
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import java.util.Map;
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import javax.annotation.Nullable;
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import com.google.common.annotations.GwtCompatible;
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import com.google.common.annotations.GwtIncompatible;
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/**
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* A {@code BiMap} backed by an {@code EnumMap} instance for keys-to-values, and
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* a {@code HashMap} instance for values-to-keys. Null keys are not permitted,
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* but null values are. An {@code EnumHashBiMap} and its inverse are both
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* serializable.
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*
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* <p>
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* See the Guava User Guide article on <a href=
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* "http://code.google.com/p/guava-libraries/wiki/NewCollectionTypesExplained#BiMap">
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* {@code BiMap}</a>.
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*
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* @author Mike Bostock
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* @since 2.0 (imported from Google Collections Library)
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*/
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@GwtCompatible(emulated = true)
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public final class EnumHashBiMap<K extends Enum<K>, V> extends AbstractBiMap<K, V> {
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private transient Class<K> keyType;
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/**
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* Returns a new, empty {@code EnumHashBiMap} using the specified key type.
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*
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* @param keyType the key type
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*/
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public static <K extends Enum<K>, V> EnumHashBiMap<K, V> create(Class<K> keyType) {
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return new EnumHashBiMap<K, V>(keyType);
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}
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/**
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* Constructs a new bimap with the same mappings as the specified map. If the
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* specified map is an {@code EnumHashBiMap} or an {@link EnumBiMap}, the new
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* bimap has the same key type as the input bimap. Otherwise, the specified map
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* must contain at least one mapping, in order to determine the key type.
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*
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* @param map the map whose mappings are to be placed in this map
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* @throws IllegalArgumentException if map is not an {@code EnumBiMap} or an
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* {@code EnumHashBiMap} instance and contains
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* no mappings
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*/
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public static <K extends Enum<K>, V> EnumHashBiMap<K, V> create(Map<K, ? extends V> map) {
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EnumHashBiMap<K, V> bimap = create(EnumBiMap.inferKeyType(map));
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bimap.putAll(map);
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return bimap;
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}
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private EnumHashBiMap(Class<K> keyType) {
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super(WellBehavedMap.wrap(new EnumMap<K, V>(keyType)),
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Maps.<V, K>newHashMapWithExpectedSize(keyType.getEnumConstants().length));
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this.keyType = keyType;
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}
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// Overriding these 3 methods to show that values may be null (but not keys)
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@Override
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K checkKey(K key) {
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return checkNotNull(key);
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}
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@Override
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public V put(K key, @Nullable V value) {
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return super.put(key, value);
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}
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@Override
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public V forcePut(K key, @Nullable V value) {
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return super.forcePut(key, value);
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}
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/** Returns the associated key type. */
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public Class<K> keyType() {
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return keyType;
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}
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/**
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* @serialData the key class, number of entries, first key, first value, second
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* key, second value, and so on.
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*/
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@GwtIncompatible("java.io.ObjectOutputStream")
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private void writeObject(ObjectOutputStream stream) throws IOException {
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stream.defaultWriteObject();
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stream.writeObject(keyType);
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Serialization.writeMap(this, stream);
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}
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@SuppressWarnings("unchecked") // reading field populated by writeObject
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@GwtIncompatible("java.io.ObjectInputStream")
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private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException {
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stream.defaultReadObject();
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keyType = (Class<K>) stream.readObject();
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setDelegates(WellBehavedMap.wrap(new EnumMap<K, V>(keyType)),
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new HashMap<V, K>(keyType.getEnumConstants().length * 3 / 2));
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Serialization.populateMap(this, stream);
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}
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@GwtIncompatible("only needed in emulated source.")
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private static final long serialVersionUID = 0;
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}
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