001/*
002 * Copyright (C) 2007 The Guava Authors
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 * http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package com.google.common.collect;
018
019import static com.google.common.base.Preconditions.checkNotNull;
020import static java.util.Objects.requireNonNull;
021
022import com.google.common.annotations.GwtCompatible;
023import com.google.common.annotations.GwtIncompatible;
024import com.google.common.annotations.J2ktIncompatible;
025import java.io.IOException;
026import java.io.ObjectInputStream;
027import java.io.ObjectOutputStream;
028import java.util.Collection;
029import java.util.Comparator;
030import java.util.NavigableMap;
031import java.util.NavigableSet;
032import java.util.SortedSet;
033import java.util.TreeMap;
034import java.util.TreeSet;
035import org.jspecify.annotations.Nullable;
036
037/**
038 * Implementation of {@code Multimap} whose keys and values are ordered by their natural ordering or
039 * by supplied comparators. In all cases, this implementation uses {@link Comparable#compareTo} or
040 * {@link Comparator#compare} instead of {@link Object#equals} to determine equivalence of
041 * instances.
042 *
043 * <p><b>Warning:</b> The comparators or comparables used must be <i>consistent with equals</i> as
044 * explained by the {@link Comparable} class specification. Otherwise, the resulting multiset will
045 * violate the general contract of {@link SetMultimap}, which is specified in terms of {@link
046 * Object#equals}.
047 *
048 * <p>The collections returned by {@code keySet} and {@code asMap} iterate through the keys
049 * according to the key comparator ordering or the natural ordering of the keys. Similarly, {@code
050 * get}, {@code removeAll}, and {@code replaceValues} return collections that iterate through the
051 * values according to the value comparator ordering or the natural ordering of the values. The
052 * collections generated by {@code entries}, {@code keys}, and {@code values} iterate across the
053 * keys according to the above key ordering, and for each key they iterate across the values
054 * according to the value ordering.
055 *
056 * <p>The multimap does not store duplicate key-value pairs. Adding a new key-value pair equal to an
057 * existing key-value pair has no effect.
058 *
059 * <p>Null keys and values are permitted (provided, of course, that the respective comparators
060 * support them). All optional multimap methods are supported, and all returned views are
061 * modifiable.
062 *
063 * <p>This class is not threadsafe when any concurrent operations update the multimap. Concurrent
064 * read operations will work correctly. To allow concurrent update operations, wrap your multimap
065 * with a call to {@link Multimaps#synchronizedSortedSetMultimap}.
066 *
067 * <p>See the Guava User Guide article on <a href=
068 * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multimap">{@code Multimap}</a>.
069 *
070 * @author Jared Levy
071 * @author Louis Wasserman
072 * @since 2.0
073 */
074@GwtCompatible
075public final class TreeMultimap<K extends @Nullable Object, V extends @Nullable Object>
076    extends AbstractSortedKeySortedSetMultimap<K, V> {
077  private transient Comparator<? super K> keyComparator;
078  private transient Comparator<? super V> valueComparator;
079
080  /**
081   * Creates an empty {@code TreeMultimap} ordered by the natural ordering of its keys and values.
082   */
083  @SuppressWarnings("rawtypes") // https://github.com/google/guava/issues/989
084  public static <K extends Comparable, V extends Comparable> TreeMultimap<K, V> create() {
085    return new TreeMultimap<>(Ordering.natural(), Ordering.natural());
086  }
087
088  /**
089   * Creates an empty {@code TreeMultimap} instance using explicit comparators. Neither comparator
090   * may be null; use {@link Ordering#natural()} to specify natural order.
091   *
092   * @param keyComparator the comparator that determines the key ordering
093   * @param valueComparator the comparator that determines the value ordering
094   */
095  public static <K extends @Nullable Object, V extends @Nullable Object> TreeMultimap<K, V> create(
096      Comparator<? super K> keyComparator, Comparator<? super V> valueComparator) {
097    return new TreeMultimap<>(checkNotNull(keyComparator), checkNotNull(valueComparator));
098  }
099
100  /**
101   * Constructs a {@code TreeMultimap}, ordered by the natural ordering of its keys and values, with
102   * the same mappings as the specified multimap.
103   *
104   * @param multimap the multimap whose contents are copied to this multimap
105   */
106  @SuppressWarnings("rawtypes") // https://github.com/google/guava/issues/989
107  public static <K extends Comparable, V extends Comparable> TreeMultimap<K, V> create(
108      Multimap<? extends K, ? extends V> multimap) {
109    return new TreeMultimap<>(Ordering.natural(), Ordering.natural(), multimap);
110  }
111
112  TreeMultimap(Comparator<? super K> keyComparator, Comparator<? super V> valueComparator) {
113    super(new TreeMap<K, Collection<V>>(keyComparator));
114    this.keyComparator = keyComparator;
115    this.valueComparator = valueComparator;
116  }
117
118  private TreeMultimap(
119      Comparator<? super K> keyComparator,
120      Comparator<? super V> valueComparator,
121      Multimap<? extends K, ? extends V> multimap) {
122    this(keyComparator, valueComparator);
123    putAll(multimap);
124  }
125
126  /**
127   * {@inheritDoc}
128   *
129   * <p>Creates an empty {@code TreeSet} for a collection of values for one key.
130   *
131   * @return a new {@code TreeSet} containing a collection of values for one key
132   */
133  @Override
134  SortedSet<V> createCollection() {
135    return new TreeSet<>(valueComparator);
136  }
137
138  @Override
139  Collection<V> createCollection(@ParametricNullness K key) {
140    if (key == null) {
141      int unused = keyComparator().compare(key, key);
142    }
143    return super.createCollection(key);
144  }
145
146  /**
147   * Returns the comparator that orders the multimap keys.
148   *
149   * @deprecated Use {@code ((NavigableSet<K>) multimap.keySet()).comparator()} instead.
150   */
151  @Deprecated
152  public Comparator<? super K> keyComparator() {
153    return keyComparator;
154  }
155
156  @Override
157  public Comparator<? super V> valueComparator() {
158    return valueComparator;
159  }
160
161  /**
162   * @since 14.0 (present with return type {@code SortedSet} since 2.0)
163   */
164  @Override
165  @GwtIncompatible // NavigableSet
166  public NavigableSet<V> get(@ParametricNullness 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
203  @J2ktIncompatible
204    private void writeObject(ObjectOutputStream stream) throws IOException {
205    stream.defaultWriteObject();
206    stream.writeObject(keyComparator());
207    stream.writeObject(valueComparator());
208    Serialization.writeMultimap(this, stream);
209  }
210
211  @GwtIncompatible
212  @J2ktIncompatible
213    @SuppressWarnings("unchecked") // reading data stored by writeObject
214  private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException {
215    stream.defaultReadObject();
216    keyComparator = requireNonNull((Comparator<? super K>) stream.readObject());
217    valueComparator = requireNonNull((Comparator<? super V>) stream.readObject());
218    setMap(new TreeMap<K, Collection<V>>(keyComparator));
219    Serialization.populateMultimap(this, stream);
220  }
221
222  @GwtIncompatible @J2ktIncompatible private static final long serialVersionUID = 0;
223}