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
17 package com.google.common.collect;
18
19 import com.google.common.annotations.GwtCompatible;
20 import com.google.errorprone.annotations.CanIgnoreReturnValue;
21 import java.util.Collection;
22 import java.util.Collections;
23 import java.util.Map;
24 import java.util.Map.Entry;
25 import java.util.Set;
26 import org.checkerframework.checker.nullness.qual.Nullable;
27
28 /**
29 * Basic implementation of the {@link SetMultimap} interface. It's a wrapper around {@link
30 * AbstractMapBasedMultimap} that converts the returned collections into {@code Sets}. The {@link
31 * #createCollection} method must return a {@code Set}.
32 *
33 * @author Jared Levy
34 */
35 @GwtCompatible
36 abstract class AbstractSetMultimap<K, V> extends AbstractMapBasedMultimap<K, V>
37 implements SetMultimap<K, V> {
38 /**
39 * Creates a new multimap that uses the provided map.
40 *
41 * @param map place to store the mapping from each key to its corresponding values
42 */
43 protected AbstractSetMultimap(Map<K, Collection<V>> map) {
44 super(map);
45 }
46
47 @Override
48 abstract Set<V> createCollection();
49
50 @Override
51 Set<V> createUnmodifiableEmptyCollection() {
52 return Collections.emptySet();
53 }
54
55 @Override
56 <E> Collection<E> unmodifiableCollectionSubclass(Collection<E> collection) {
57 return Collections.unmodifiableSet((Set<E>) collection);
58 }
59
60 @Override
61 Collection<V> wrapCollection(K key, Collection<V> collection) {
62 return new WrappedSet(key, (Set<V>) collection);
63 }
64
65 // Following Javadoc copied from SetMultimap.
66
67 /**
68 * {@inheritDoc}
69 *
70 * <p>Because a {@code SetMultimap} has unique values for a given key, this method returns a
71 * {@link Set}, instead of the {@link Collection} specified in the {@link Multimap} interface.
72 */
73 @Override
74 public Set<V> get(@Nullable K key) {
75 return (Set<V>) super.get(key);
76 }
77
78 /**
79 * {@inheritDoc}
80 *
81 * <p>Because a {@code SetMultimap} has unique values for a given key, this method returns a
82 * {@link Set}, instead of the {@link Collection} specified in the {@link Multimap} interface.
83 */
84 @Override
85 public Set<Entry<K, V>> entries() {
86 return (Set<Entry<K, V>>) super.entries();
87 }
88
89 /**
90 * {@inheritDoc}
91 *
92 * <p>Because a {@code SetMultimap} has unique values for a given key, this method returns a
93 * {@link Set}, instead of the {@link Collection} specified in the {@link Multimap} interface.
94 */
95 @CanIgnoreReturnValue
96 @Override
97 public Set<V> removeAll(@Nullable Object key) {
98 return (Set<V>) super.removeAll(key);
99 }
100
101 /**
102 * {@inheritDoc}
103 *
104 * <p>Because a {@code SetMultimap} has unique values for a given key, this method returns a
105 * {@link Set}, instead of the {@link Collection} specified in the {@link Multimap} interface.
106 *
107 * <p>Any duplicates in {@code values} will be stored in the multimap once.
108 */
109 @CanIgnoreReturnValue
110 @Override
111 public Set<V> replaceValues(@Nullable K key, Iterable<? extends V> values) {
112 return (Set<V>) super.replaceValues(key, values);
113 }
114
115 /**
116 * {@inheritDoc}
117 *
118 * <p>Though the method signature doesn't say so explicitly, the returned map has {@link Set}
119 * values.
120 */
121 @Override
122 public Map<K, Collection<V>> asMap() {
123 return super.asMap();
124 }
125
126 /**
127 * Stores a key-value pair in the multimap.
128 *
129 * @param key key to store in the multimap
130 * @param value value to store in the multimap
131 * @return {@code true} if the method increased the size of the multimap, or {@code false} if the
132 * multimap already contained the key-value pair
133 */
134 @CanIgnoreReturnValue
135 @Override
136 public boolean put(@Nullable K key, @Nullable V value) {
137 return super.put(key, value);
138 }
139
140 /**
141 * Compares the specified object to this multimap for equality.
142 *
143 * <p>Two {@code SetMultimap} instances are equal if, for each key, they contain the same values.
144 * Equality does not depend on the ordering of keys or values.
145 */
146 @Override
147 public boolean equals(@Nullable Object object) {
148 return super.equals(object);
149 }
150
151 private static final long serialVersionUID = 7431625294878419160L;
152 }