1/*
2 * Copyright (C) 2007 The Guava Authors
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
5 * in compliance with the License. You may obtain a copy of the License at
6 *
7 * http://www.apache.org/licenses/LICENSE-2.0
8 *
9 * Unless required by applicable law or agreed to in writing, software distributed under the License
10 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
11 * or implied. See the License for the specific language governing permissions and limitations under
12 * the License.
13 */
14
15package com.google.common.collect;
16
17import static com.google.common.base.Preconditions.checkArgument;
18
19import com.google.common.annotations.GwtCompatible;
20import com.google.common.annotations.GwtIncompatible;
21
22import java.io.IOException;
23import java.io.ObjectInputStream;
24import java.io.ObjectOutputStream;
25import java.util.EnumMap;
26import java.util.Iterator;
27
28/**
29 * Multiset implementation backed by an {@link EnumMap}.
30 *
31 * @author Jared Levy
32 * @since 2.0 (imported from Google Collections Library)
33 */
34@GwtCompatible(emulated = true)
35public final class EnumMultiset<E extends Enum<E>> extends AbstractMapBasedMultiset<E> {
36  /** Creates an empty {@code EnumMultiset}. */
37  public static <E extends Enum<E>> EnumMultiset<E> create(Class<E> type) {
38    return new EnumMultiset<E>(type);
39  }
40
41  /**
42   * Creates a new {@code EnumMultiset} containing the specified elements.
43   *
44   * <p>This implementation is highly efficient when {@code elements} is itself a {@link
45   * Multiset}.
46   *
47   * @param elements the elements that the multiset should contain
48   * @throws IllegalArgumentException if {@code elements} is empty
49   */
50  public static <E extends Enum<E>> EnumMultiset<E> create(Iterable<E> elements) {
51    Iterator<E> iterator = elements.iterator();
52    checkArgument(iterator.hasNext(), "EnumMultiset constructor passed empty Iterable");
53    EnumMultiset<E> multiset = new EnumMultiset<E>(iterator.next().getDeclaringClass());
54    Iterables.addAll(multiset, elements);
55    return multiset;
56  }
57
58  private transient Class<E> type;
59
60  /** Creates an empty {@code EnumMultiset}. */
61  private EnumMultiset(Class<E> type) {
62    super(WellBehavedMap.wrap(new EnumMap<E, Count>(type)));
63    this.type = type;
64  }
65
66  @GwtIncompatible("java.io.ObjectOutputStream")
67  private void writeObject(ObjectOutputStream stream) throws IOException {
68    stream.defaultWriteObject();
69    stream.writeObject(type);
70    Serialization.writeMultiset(this, stream);
71  }
72
73  /**
74   * @serialData the {@code Class<E>} for the enum type, the number of distinct
75   *             elements, the first element, its count, the second element, its
76   *             count, and so on
77   */
78  @GwtIncompatible("java.io.ObjectInputStream")
79  private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException {
80    stream.defaultReadObject();
81    @SuppressWarnings("unchecked") // reading data stored by writeObject
82    Class<E> localType = (Class<E>) stream.readObject();
83    type = localType;
84    setBackingMap(WellBehavedMap.wrap(new EnumMap<E, Count>(type)));
85    Serialization.populateMultiset(this, stream);
86  }
87
88  @GwtIncompatible("Not needed in emulated source")
89  private static final long serialVersionUID = 0;
90}
91