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 it 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
068 * Multimap}</a>.
069 *
070 * @author Jared Levy
071 * @author Louis Wasserman
072 * @since 2.0
073 */
074@GwtCompatible(serializable = true, emulated = true)
075public class TreeMultimap<K, V> extends AbstractSortedKeySortedSetMultimap<K, V> {
076  private transient Comparator<? super K> keyComparator;
077  private transient Comparator<? super V> valueComparator;
078
079  /**
080   * Creates an empty {@code TreeMultimap} ordered by the natural ordering of its keys and values.
081   */
082  public static <K extends Comparable, V extends Comparable> TreeMultimap<K, V> create() {
083    return new TreeMultimap<>(Ordering.natural(), Ordering.natural());
084  }
085
086  /**
087   * Creates an empty {@code TreeMultimap} instance using explicit comparators. Neither comparator
088   * may be null; use {@link Ordering#natural()} to specify natural order.
089   *
090   * @param keyComparator the comparator that determines the key ordering
091   * @param valueComparator the comparator that determines the value ordering
092   */
093  public static <K, V> TreeMultimap<K, V> create(
094      Comparator<? super K> keyComparator, Comparator<? super V> valueComparator) {
095    return new TreeMultimap<>(checkNotNull(keyComparator), checkNotNull(valueComparator));
096  }
097
098  /**
099   * 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}