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;
20
21import java.util.EnumMap;
22import java.util.Iterator;
23
24/**
25 * Multiset implementation backed by an {@link EnumMap}.
26 *
27 * <p>See the Guava User Guide article on <a href=
28 * "http://code.google.com/p/guava-libraries/wiki/NewCollectionTypesExplained#Multiset">
29 * {@code Multiset}</a>.
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  /**
59   * Returns a new {@code EnumMultiset} instance containing the given elements.  Unlike
60   * {@link EnumMultiset#create(Iterable)}, this method does not produce an exception on an empty
61   * iterable.
62   *
63   * @since 14.0
64   */
65  public static <E extends Enum<E>> EnumMultiset<E> create(Iterable<E> elements, Class<E> type) {
66    EnumMultiset<E> result = create(type);
67    Iterables.addAll(result, elements);
68    return result;
69  }
70
71  private transient Class<E> type;
72
73  /** Creates an empty {@code EnumMultiset}. */
74  private EnumMultiset(Class<E> type) {
75    super(WellBehavedMap.wrap(new EnumMap<E, Count>(type)));
76    this.type = type;
77  }
78}
79
80