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;
020
021import com.google.common.annotations.GwtCompatible;
022import com.google.common.annotations.GwtIncompatible;
023import java.io.IOException;
024import java.io.ObjectInputStream;
025import java.io.ObjectOutputStream;
026import java.util.Collection;
027import java.util.Comparator;
028import java.util.Map;
029import java.util.NavigableMap;
030import java.util.NavigableSet;
031import java.util.SortedSet;
032import java.util.TreeMap;
033import java.util.TreeSet;
034import org.checkerframework.checker.nullness.qual.Nullable;
035
036/**
037 * Implementation of {@code Multimap} whose keys and values are ordered by their natural ordering or
038 * by supplied comparators. In all cases, this implementation uses {@link Comparable#compareTo} or
039 * {@link Comparator#compare} instead of {@link Object#equals} to determine equivalence of
040 * instances.
041 *
042 * <p><b>Warning:</b> The comparators or comparables used must be <i>consistent with equals</i> as
043 * explained by the {@link Comparable} class specification. Otherwise, the resulting multiset will
044 * violate the general contract of {@link SetMultimap}, which is specified in terms of {@link
045 * Object#equals}.
046 *
047 * <p>The collections returned by {@code keySet} and {@code asMap} iterate through the keys
048 * according to the key comparator ordering or the natural ordering of the keys. Similarly, {@code
049 * get}, {@code removeAll}, and {@code replaceValues} return collections that iterate through the
050 * values according to the value comparator ordering or the natural ordering of the values. The
051 * collections generated by {@code entries}, {@code keys}, and {@code values} iterate across the
052 * keys according to the above key ordering, and for each key they iterate across the values
053 * according to the value ordering.
054 *
055 * <p>The multimap does not store duplicate key-value pairs. Adding a new key-value pair equal to an
056 * existing key-value pair has no effect.
057 *
058 * <p>Null keys and values are permitted (provided, of course, that the respective comparators
059 * support them). All optional multimap methods are supported, and all returned views are
060 * modifiable.
061 *
062 * <p>This class is not threadsafe when any concurrent operations update the multimap. Concurrent
063 * read operations will work correctly. To allow concurrent update operations, wrap your multimap
064 * with a call to {@link Multimaps#synchronizedSortedSetMultimap}.
065 *
066 * <p>See the Guava User Guide article on <a href=
067 * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multimap">{@code Multimap}</a>.
068 *
069 * @author Jared Levy
070 * @author Louis Wasserman
071 * @since 2.0
072 */
073@GwtCompatible(serializable = true, emulated = true)
074@ElementTypesAreNonnullByDefault
075public 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  public static <K extends Comparable, V extends Comparable> TreeMultimap<K, V> create() {
084    return new TreeMultimap<>(Ordering.natural(), Ordering.natural());
085  }
086
087  /**
088   * Creates an empty {@code TreeMultimap} instance using explicit comparators. Neither comparator
089   * may be null; use {@link Ordering#natural()} to specify natural order.
090   *
091   * @param keyComparator the comparator that determines the key ordering
092   * @param valueComparator the comparator that determines the value ordering
093   */
094  public static <K extends @Nullable Object, V extends @Nullable Object> TreeMultimap<K, V> create(
095      Comparator<? super K> keyComparator, Comparator<? super V> valueComparator) {
096    return new TreeMultimap<>(checkNotNull(keyComparator), checkNotNull(valueComparator));
097  }
098
099  /**
100   * Constructs a {@code TreeMultimap}, ordered by the natural ordering of its keys and values, with
101   * the same mappings as the specified multimap.
102   *
103   * @param multimap the multimap whose contents are copied to this multimap
104   */
105  public static <K extends Comparable, V extends Comparable> TreeMultimap<K, V> create(
106      Multimap<? extends K, ? extends V> multimap) {
107    return new TreeMultimap<>(Ordering.natural(), Ordering.natural(), multimap);
108  }
109
110  TreeMultimap(Comparator<? super K> keyComparator, Comparator<? super V> valueComparator) {
111    super(new TreeMap<K, Collection<V>>(keyComparator));
112    this.keyComparator = keyComparator;
113    this.valueComparator = valueComparator;
114  }
115
116  private TreeMultimap(
117      Comparator<? super K> keyComparator,
118      Comparator<? super V> valueComparator,
119      Multimap<? extends K, ? extends V> multimap) {
120    this(keyComparator, valueComparator);
121    putAll(multimap);
122  }
123
124  @Override
125  Map<K, Collection<V>> createAsMap() {
126    return createMaybeNavigableAsMap();
127  }
128
129  /**
130   * {@inheritDoc}
131   *
132   * <p>Creates an empty {@code TreeSet} for a collection of values for one key.
133   *
134   * @return a new {@code TreeSet} containing a collection of values for one key
135   */
136  @Override
137  SortedSet<V> createCollection() {
138    return new TreeSet<>(valueComparator);
139  }
140
141  @Override
142  Collection<V> createCollection(@ParametricNullness K key) {
143    if (key == null) {
144      int unused = keyComparator().compare(key, key);
145    }
146    return super.createCollection(key);
147  }
148
149  /**
150   * Returns the comparator that orders the multimap keys.
151   *
152   * @deprecated Use {@code ((NavigableSet<K>) multimap.keySet()).comparator()} instead.
153   */
154  @Deprecated
155  public Comparator<? super K> keyComparator() {
156    return keyComparator;
157  }
158
159  @Override
160  public Comparator<? super V> valueComparator() {
161    return valueComparator;
162  }
163
164  /** @since 14.0 (present with return type {@code SortedSet} since 2.0) */
165  @Override
166  @GwtIncompatible // NavigableSet
167  public NavigableSet<V> get(@ParametricNullness K key) {
168    return (NavigableSet<V>) super.get(key);
169  }
170
171  /**
172   * {@inheritDoc}
173   *
174   * <p>Because a {@code TreeMultimap} has unique sorted keys, this method returns a {@link
175   * NavigableSet}, instead of the {@link java.util.Set} specified in the {@link Multimap}
176   * interface.
177   *
178   * @since 14.0 (present with return type {@code SortedSet} since 2.0)
179   */
180  @Override
181  public NavigableSet<K> keySet() {
182    return (NavigableSet<K>) super.keySet();
183  }
184
185  /**
186   * {@inheritDoc}
187   *
188   * <p>Because a {@code TreeMultimap} has unique sorted keys, this method returns a {@link
189   * NavigableMap}, instead of the {@link java.util.Map} specified in the {@link Multimap}
190   * interface.
191   *
192   * @since 14.0 (present with return type {@code SortedMap} since 2.0)
193   */
194  @Override
195  public NavigableMap<K, Collection<V>> asMap() {
196    return (NavigableMap<K, Collection<V>>) super.asMap();
197  }
198
199  /**
200   * @serialData key comparator, value comparator, number of distinct keys, and then for each
201   *     distinct key: the key, number of values for that key, and key values
202   */
203  @GwtIncompatible // java.io.ObjectOutputStream
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 // java.io.ObjectInputStream
212  @SuppressWarnings("unchecked") // reading data stored by writeObject
213  private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException {
214    stream.defaultReadObject();
215    keyComparator = checkNotNull((Comparator<? super K>) stream.readObject());
216    valueComparator = checkNotNull((Comparator<? super V>) stream.readObject());
217    setMap(new TreeMap<K, Collection<V>>(keyComparator));
218    Serialization.populateMultimap(this, stream);
219  }
220
221  @GwtIncompatible // not needed in emulated source
222  private static final long serialVersionUID = 0;
223}