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 static com.google.common.base.Preconditions.checkNotNull;
20
21 import com.google.common.annotations.GwtCompatible;
22 import com.google.common.annotations.GwtIncompatible;
23 import java.io.IOException;
24 import java.io.ObjectInputStream;
25 import java.io.ObjectOutputStream;
26 import java.util.Collection;
27 import java.util.Comparator;
28 import java.util.Map;
29 import java.util.NavigableMap;
30 import java.util.NavigableSet;
31 import java.util.SortedSet;
32 import java.util.TreeMap;
33 import java.util.TreeSet;
34 import org.checkerframework.checker.nullness.qual.Nullable;
35
36 /**
37 * Implementation of {@code Multimap} whose keys and values are ordered by their natural ordering or
38 * by supplied comparators. In all cases, this implementation uses {@link Comparable#compareTo} or
39 * {@link Comparator#compare} instead of {@link Object#equals} to determine equivalence of
40 * instances.
41 *
42 * <p><b>Warning:</b> The comparators or comparables used must be <i>consistent with equals</i> as
43 * explained by the {@link Comparable} class specification. Otherwise, the resulting multiset will
44 * violate the general contract of {@link SetMultimap}, which is specified in terms of {@link
45 * Object#equals}.
46 *
47 * <p>The collections returned by {@code keySet} and {@code asMap} iterate through the keys
48 * according to the key comparator ordering or the natural ordering of the keys. Similarly, {@code
49 * get}, {@code removeAll}, and {@code replaceValues} return collections that iterate through the
50 * values according to the value comparator ordering or the natural ordering of the values. The
51 * collections generated by {@code entries}, {@code keys}, and {@code values} iterate across the
52 * keys according to the above key ordering, and for each key they iterate across the values
53 * according to the value ordering.
54 *
55 * <p>The multimap does not store duplicate key-value pairs. Adding a new key-value pair equal to an
56 * existing key-value pair has no effect.
57 *
58 * <p>Null keys and values are permitted (provided, of course, that the respective comparators
59 * support them). All optional multimap methods are supported, and all returned views are
60 * modifiable.
61 *
62 * <p>This class is not threadsafe when any concurrent operations update the multimap. Concurrent
63 * read operations will work correctly. To allow concurrent update operations, wrap your multimap
64 * with a call to {@link Multimaps#synchronizedSortedSetMultimap}.
65 *
66 * <p>See the Guava User Guide article on <a href=
67 * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multimap"> {@code
68 * Multimap}</a>.
69 *
70 * @author Jared Levy
71 * @author Louis Wasserman
72 * @since 2.0
73 */
74 @GwtCompatible(serializable = true, emulated = true)
75 public class TreeMultimap<K, V> extends AbstractSortedKeySortedSetMultimap<K, V> {
76 private transient Comparator<? super K> keyComparator;
77 private transient Comparator<? super V> valueComparator;
78
79 /**
80 * Creates an empty {@code TreeMultimap} ordered by the natural ordering of its keys and values.
81 */
82 public static <K extends Comparable, V extends Comparable> TreeMultimap<K, V> create() {
83 return new TreeMultimap<>(Ordering.natural(), Ordering.natural());
84 }
85
86 /**
87 * Creates an empty {@code TreeMultimap} instance using explicit comparators. Neither comparator
88 * may be null; use {@link Ordering#natural()} to specify natural order.
89 *
90 * @param keyComparator the comparator that determines the key ordering
91 * @param valueComparator the comparator that determines the value ordering
92 */
93 public static <K, V> TreeMultimap<K, V> create(
94 Comparator<? super K> keyComparator, Comparator<? super V> valueComparator) {
95 return new TreeMultimap<>(checkNotNull(keyComparator), checkNotNull(valueComparator));
96 }
97
98 /**
99 * Constructs a {@code TreeMultimap}, ordered by the natural ordering of its keys and values, with
100 * the same mappings as the specified multimap.
101 *
102 * @param multimap the multimap whose contents are copied to this multimap
103 */
104 public static <K extends Comparable, V extends Comparable> TreeMultimap<K, V> create(
105 Multimap<? extends K, ? extends V> multimap) {
106 return new TreeMultimap<>(Ordering.natural(), Ordering.natural(), multimap);
107 }
108
109 TreeMultimap(Comparator<? super K> keyComparator, Comparator<? super V> valueComparator) {
110 super(new TreeMap<K, Collection<V>>(keyComparator));
111 this.keyComparator = keyComparator;
112 this.valueComparator = valueComparator;
113 }
114
115 private TreeMultimap(
116 Comparator<? super K> keyComparator,
117 Comparator<? super V> valueComparator,
118 Multimap<? extends K, ? extends V> multimap) {
119 this(keyComparator, valueComparator);
120 putAll(multimap);
121 }
122
123 @Override
124 Map<K, Collection<V>> createAsMap() {
125 return createMaybeNavigableAsMap();
126 }
127
128 /**
129 * {@inheritDoc}
130 *
131 * <p>Creates an empty {@code TreeSet} for a collection of values for one key.
132 *
133 * @return a new {@code TreeSet} containing a collection of values for one key
134 */
135 @Override
136 SortedSet<V> createCollection() {
137 return new TreeSet<V>(valueComparator);
138 }
139
140 @Override
141 Collection<V> createCollection(@Nullable K key) {
142 if (key == null) {
143 keyComparator().compare(key, key);
144 }
145 return super.createCollection(key);
146 }
147
148 /**
149 * Returns the comparator that orders the multimap keys.
150 *
151 * @deprecated Use {@code ((NavigableSet<K>) multimap.keySet()).comparator()} instead.
152 */
153 @Deprecated
154 public Comparator<? super K> keyComparator() {
155 return keyComparator;
156 }
157
158 @Override
159 public Comparator<? super V> valueComparator() {
160 return valueComparator;
161 }
162
163 /** @since 14.0 (present with return type {@code SortedSet} since 2.0) */
164 @Override
165 @GwtIncompatible // NavigableSet
166 public NavigableSet<V> get(@Nullable K key) {
167 return (NavigableSet<V>) super.get(key);
168 }
169
170 /**
171 * {@inheritDoc}
172 *
173 * <p>Because a {@code TreeMultimap} has unique sorted keys, this method returns a {@link
174 * NavigableSet}, instead of the {@link java.util.Set} specified in the {@link Multimap}
175 * interface.
176 *
177 * @since 14.0 (present with return type {@code SortedSet} since 2.0)
178 */
179 @Override
180 public NavigableSet<K> keySet() {
181 return (NavigableSet<K>) super.keySet();
182 }
183
184 /**
185 * {@inheritDoc}
186 *
187 * <p>Because a {@code TreeMultimap} has unique sorted keys, this method returns a {@link
188 * NavigableMap}, instead of the {@link java.util.Map} specified in the {@link Multimap}
189 * interface.
190 *
191 * @since 14.0 (present with return type {@code SortedMap} since 2.0)
192 */
193 @Override
194 public NavigableMap<K, Collection<V>> asMap() {
195 return (NavigableMap<K, Collection<V>>) super.asMap();
196 }
197
198 /**
199 * @serialData key comparator, value comparator, number of distinct keys, and then for each
200 * distinct key: the key, number of values for that key, and key values
201 */
202 @GwtIncompatible // java.io.ObjectOutputStream
203 private void writeObject(ObjectOutputStream stream) throws IOException {
204 stream.defaultWriteObject();
205 stream.writeObject(keyComparator());
206 stream.writeObject(valueComparator());
207 Serialization.writeMultimap(this, stream);
208 }
209
210 @GwtIncompatible // java.io.ObjectInputStream
211 @SuppressWarnings("unchecked") // reading data stored by writeObject
212 private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException {
213 stream.defaultReadObject();
214 keyComparator = checkNotNull((Comparator<? super K>) stream.readObject());
215 valueComparator = checkNotNull((Comparator<? super V>) stream.readObject());
216 setMap(new TreeMap<K, Collection<V>>(keyComparator));
217 Serialization.populateMultimap(this, stream);
218 }
219
220 @GwtIncompatible // not needed in emulated source
221 private static final long serialVersionUID = 0;
222 }