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;
020
021import com.google.common.annotations.GwtCompatible;
022import com.google.common.annotations.GwtIncompatible;
023
024import java.io.IOException;
025import java.io.ObjectInputStream;
026import java.io.ObjectOutputStream;
027import java.util.EnumMap;
028import java.util.Iterator;
029import java.util.concurrent.atomic.AtomicInteger;
030
031/**
032 * Multiset implementation backed by an {@link EnumMap}.
033 *
034 * @author Jared Levy
035 * @since 2 (imported from Google Collections Library)
036 */
037@GwtCompatible(emulated = true)
038public final class EnumMultiset<E extends Enum<E>> extends AbstractMapBasedMultiset<E> {
039  /** Creates an empty {@code EnumMultiset}. */
040  public static <E extends Enum<E>> EnumMultiset<E> create(Class<E> type) {
041    return new EnumMultiset<E>(type);
042  }
043
044  /**
045   * Creates a new {@code EnumMultiset} containing the specified elements.
046   *
047   * @param elements the elements that the multiset should contain
048   * @throws IllegalArgumentException if {@code elements} is empty
049   */
050  public static <E extends Enum<E>> EnumMultiset<E> create(Iterable<E> elements) {
051    Iterator<E> iterator = elements.iterator();
052    checkArgument(iterator.hasNext(), "EnumMultiset constructor passed empty Iterable");
053    EnumMultiset<E> multiset = new EnumMultiset<E>(iterator.next().getDeclaringClass());
054    Iterables.addAll(multiset, elements);
055    return multiset;
056  }
057
058  private transient Class<E> type;
059
060  /** Creates an empty {@code EnumMultiset}. */
061  private EnumMultiset(Class<E> type) {
062    super(WellBehavedMap.wrap(new EnumMap<E, AtomicInteger>(type)));
063    this.type = type;
064  }
065
066  @GwtIncompatible("java.io.ObjectOutputStream")
067  private void writeObject(ObjectOutputStream stream) throws IOException {
068    stream.defaultWriteObject();
069    stream.writeObject(type);
070    Serialization.writeMultiset(this, stream);
071  }
072
073  /**
074   * @serialData the {@code Class<E>} for the enum type, the number of distinct
075   *             elements, the first element, its count, the second element, its
076   *             count, and so on
077   */
078  @GwtIncompatible("java.io.ObjectInputStream")
079  private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException {
080    stream.defaultReadObject();
081    @SuppressWarnings("unchecked") // reading data stored by writeObject
082    Class<E> localType = (Class<E>) stream.readObject();
083    type = localType;
084    setBackingMap(WellBehavedMap.wrap(new EnumMap<E, AtomicInteger>(type)));
085    Serialization.populateMultiset(this, stream);
086  }
087
088  @GwtIncompatible("Not needed in emulated source")
089  private static final long serialVersionUID = 0;
090}