1/*
2 * Copyright (C) 2007 The Guava Authors
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package com.google.common.collect;
18
19import com.google.common.annotations.GwtCompatible;
20
21import java.util.Collection;
22import java.util.Map;
23import java.util.Set;
24
25import javax.annotation.Nullable;
26
27/**
28 * Basic implementation of the {@link SetMultimap} interface. It's a wrapper
29 * around {@link AbstractMapBasedMultimap} that converts the returned collections into
30 * {@code Sets}. The {@link #createCollection} method must return a {@code Set}.
31 *
32 * @author Jared Levy
33 */
34@GwtCompatible
35abstract class AbstractSetMultimap<K, V>
36    extends AbstractMapBasedMultimap<K, V> implements SetMultimap<K, V> {
37  /**
38   * Creates a new multimap that uses the provided map.
39   *
40   * @param map place to store the mapping from each key to its corresponding
41   *     values
42   */
43  protected AbstractSetMultimap(Map<K, Collection<V>> map) {
44    super(map);
45  }
46
47  @Override abstract Set<V> createCollection();
48
49  @Override Set<V> createUnmodifiableEmptyCollection() {
50    return ImmutableSet.of();
51  }
52
53  // Following Javadoc copied from SetMultimap.
54
55  /**
56   * {@inheritDoc}
57   *
58   * <p>Because a {@code SetMultimap} has unique values for a given key, this
59   * method returns a {@link Set}, instead of the {@link Collection} specified
60   * in the {@link Multimap} interface.
61   */
62  @Override public Set<V> get(@Nullable K key) {
63    return (Set<V>) super.get(key);
64  }
65
66  /**
67   * {@inheritDoc}
68   *
69   * <p>Because a {@code SetMultimap} has unique values for a given key, this
70   * method returns a {@link Set}, instead of the {@link Collection} specified
71   * in the {@link Multimap} interface.
72   */
73  @Override public Set<Map.Entry<K, V>> entries() {
74    return (Set<Map.Entry<K, V>>) super.entries();
75  }
76
77  /**
78   * {@inheritDoc}
79   *
80   * <p>Because a {@code SetMultimap} has unique values for a given key, this
81   * method returns a {@link Set}, instead of the {@link Collection} specified
82   * in the {@link Multimap} interface.
83   */
84  @Override public Set<V> removeAll(@Nullable Object key) {
85    return (Set<V>) super.removeAll(key);
86  }
87
88  /**
89   * {@inheritDoc}
90   *
91   * <p>Because a {@code SetMultimap} has unique values for a given key, this
92   * method returns a {@link Set}, instead of the {@link Collection} specified
93   * in the {@link Multimap} interface.
94   *
95   * <p>Any duplicates in {@code values} will be stored in the multimap once.
96   */
97  @Override public Set<V> replaceValues(
98      @Nullable K key, Iterable<? extends V> values) {
99    return (Set<V>) super.replaceValues(key, values);
100  }
101
102  /**
103   * {@inheritDoc}
104   *
105   * <p>Though the method signature doesn't say so explicitly, the returned map
106   * has {@link Set} values.
107   */
108  @Override public Map<K, Collection<V>> asMap() {
109    return super.asMap();
110  }
111
112  /**
113   * Stores a key-value pair in the multimap.
114   *
115   * @param key key to store in the multimap
116   * @param value value to store in the multimap
117   * @return {@code true} if the method increased the size of the multimap, or
118   *     {@code false} if the multimap already contained the key-value pair
119   */
120  @Override public boolean put(@Nullable K key, @Nullable V value) {
121    return super.put(key, value);
122  }
123
124  /**
125   * Compares the specified object to this multimap for equality.
126   *
127   * <p>Two {@code SetMultimap} instances are equal if, for each key, they
128   * contain the same values. Equality does not depend on the ordering of keys
129   * or values.
130   */
131  @Override public boolean equals(@Nullable Object object) {
132    return super.equals(object);
133  }
134
135  private static final long serialVersionUID = 7431625294878419160L;
136}
137