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 com.google.common.annotations.J2ktIncompatible;
024import java.io.IOException;
025import java.io.ObjectInputStream;
026import java.io.ObjectOutputStream;
027import java.util.Collection;
028import java.util.Comparator;
029import java.util.Map;
030import java.util.NavigableMap;
031import java.util.NavigableSet;
032import java.util.SortedSet;
033import java.util.TreeMap;
034import java.util.TreeSet;
035import org.checkerframework.checker.nullness.qual.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(serializable = true, emulated = true)
075@ElementTypesAreNonnullByDefault
076public class TreeMultimap<K extends @Nullable Object, V extends @Nullable Object>
077    extends AbstractSortedKeySortedSetMultimap<K, V> {
078  private transient Comparator<? super K> keyComparator;
079  private transient Comparator<? super V> valueComparator;
080
081  /**
082   * Creates an empty {@code TreeMultimap} ordered by the natural ordering of its keys and values.
083   */
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  public static <K extends Comparable, V extends Comparable> TreeMultimap<K, V> create(
107      Multimap<? extends K, ? extends V> multimap) {
108    return new TreeMultimap<>(Ordering.natural(), Ordering.natural(), multimap);
109  }
110
111  TreeMultimap(Comparator<? super K> keyComparator, Comparator<? super V> valueComparator) {
112    super(new TreeMap<K, Collection<V>>(keyComparator));
113    this.keyComparator = keyComparator;
114    this.valueComparator = valueComparator;
115  }
116
117  private TreeMultimap(
118      Comparator<? super K> keyComparator,
119      Comparator<? super V> valueComparator,
120      Multimap<? extends K, ? extends V> multimap) {
121    this(keyComparator, valueComparator);
122    putAll(multimap);
123  }
124
125  @Override
126  Map<K, Collection<V>> createAsMap() {
127    return createMaybeNavigableAsMap();
128  }
129
130  /**
131   * {@inheritDoc}
132   *
133   * <p>Creates an empty {@code TreeSet} for a collection of values for one key.
134   *
135   * @return a new {@code TreeSet} containing a collection of values for one key
136   */
137  @Override
138  SortedSet<V> createCollection() {
139    return new TreeSet<>(valueComparator);
140  }
141
142  @Override
143  Collection<V> createCollection(@ParametricNullness K key) {
144    if (key == null) {
145      int unused = keyComparator().compare(key, key);
146    }
147    return super.createCollection(key);
148  }
149
150  /**
151   * Returns the comparator that orders the multimap keys.
152   *
153   * @deprecated Use {@code ((NavigableSet<K>) multimap.keySet()).comparator()} instead.
154   */
155  @Deprecated
156  public Comparator<? super K> keyComparator() {
157    return keyComparator;
158  }
159
160  @Override
161  public Comparator<? super V> valueComparator() {
162    return valueComparator;
163  }
164
165  /** @since 14.0 (present with return type {@code SortedSet} since 2.0) */
166  @Override
167  @GwtIncompatible // NavigableSet
168  public NavigableSet<V> get(@ParametricNullness K key) {
169    return (NavigableSet<V>) super.get(key);
170  }
171
172  /**
173   * {@inheritDoc}
174   *
175   * <p>Because a {@code TreeMultimap} has unique sorted keys, this method returns a {@link
176   * NavigableSet}, instead of the {@link java.util.Set} specified in the {@link Multimap}
177   * interface.
178   *
179   * @since 14.0 (present with return type {@code SortedSet} since 2.0)
180   */
181  @Override
182  public NavigableSet<K> keySet() {
183    return (NavigableSet<K>) super.keySet();
184  }
185
186  /**
187   * {@inheritDoc}
188   *
189   * <p>Because a {@code TreeMultimap} has unique sorted keys, this method returns a {@link
190   * NavigableMap}, instead of the {@link java.util.Map} specified in the {@link Multimap}
191   * interface.
192   *
193   * @since 14.0 (present with return type {@code SortedMap} since 2.0)
194   */
195  @Override
196  public NavigableMap<K, Collection<V>> asMap() {
197    return (NavigableMap<K, Collection<V>>) super.asMap();
198  }
199
200  /**
201   * @serialData key comparator, value comparator, number of distinct keys, and then for each
202   *     distinct key: the key, number of values for that key, and key values
203   */
204  @GwtIncompatible // java.io.ObjectOutputStream
205  @J2ktIncompatible
206  private void writeObject(ObjectOutputStream stream) throws IOException {
207    stream.defaultWriteObject();
208    stream.writeObject(keyComparator());
209    stream.writeObject(valueComparator());
210    Serialization.writeMultimap(this, stream);
211  }
212
213  @GwtIncompatible // java.io.ObjectInputStream
214  @J2ktIncompatible
215  @SuppressWarnings("unchecked") // reading data stored by writeObject
216  private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException {
217    stream.defaultReadObject();
218    keyComparator = checkNotNull((Comparator<? super K>) stream.readObject());
219    valueComparator = checkNotNull((Comparator<? super V>) stream.readObject());
220    setMap(new TreeMap<K, Collection<V>>(keyComparator));
221    Serialization.populateMultimap(this, stream);
222  }
223
224  @GwtIncompatible // not needed in emulated source
225  @J2ktIncompatible
226  private static final long serialVersionUID = 0;
227}