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.Map;
031import java.util.NavigableMap;
032import java.util.NavigableSet;
033import java.util.SortedSet;
034import java.util.TreeMap;
035import java.util.TreeSet;
036import org.checkerframework.checker.nullness.qual.Nullable;
037
038/**
039 * Implementation of {@code Multimap} whose keys and values are ordered by their natural ordering or
040 * by supplied comparators. In all cases, this implementation uses {@link Comparable#compareTo} or
041 * {@link Comparator#compare} instead of {@link Object#equals} to determine equivalence of
042 * instances.
043 *
044 * <p><b>Warning:</b> The comparators or comparables used must be <i>consistent with equals</i> as
045 * explained by the {@link Comparable} class specification. Otherwise, the resulting multiset will
046 * violate the general contract of {@link SetMultimap}, which is specified in terms of {@link
047 * Object#equals}.
048 *
049 * <p>The collections returned by {@code keySet} and {@code asMap} iterate through the keys
050 * according to the key comparator ordering or the natural ordering of the keys. Similarly, {@code
051 * get}, {@code removeAll}, and {@code replaceValues} return collections that iterate through the
052 * values according to the value comparator ordering or the natural ordering of the values. The
053 * collections generated by {@code entries}, {@code keys}, and {@code values} iterate across the
054 * keys according to the above key ordering, and for each key they iterate across the values
055 * according to the value ordering.
056 *
057 * <p>The multimap does not store duplicate key-value pairs. Adding a new key-value pair equal to an
058 * existing key-value pair has no effect.
059 *
060 * <p>Null keys and values are permitted (provided, of course, that the respective comparators
061 * support them). All optional multimap methods are supported, and all returned views are
062 * modifiable.
063 *
064 * <p>This class is not threadsafe when any concurrent operations update the multimap. Concurrent
065 * read operations will work correctly. To allow concurrent update operations, wrap your multimap
066 * with a call to {@link Multimaps#synchronizedSortedSetMultimap}.
067 *
068 * <p>See the Guava User Guide article on <a href=
069 * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multimap">{@code Multimap}</a>.
070 *
071 * @author Jared Levy
072 * @author Louis Wasserman
073 * @since 2.0
074 */
075@GwtCompatible(serializable = true, emulated = true)
076@ElementTypesAreNonnullByDefault
077public class TreeMultimap<K extends @Nullable Object, V extends @Nullable Object>
078    extends AbstractSortedKeySortedSetMultimap<K, V> {
079  private transient Comparator<? super K> keyComparator;
080  private transient Comparator<? super V> valueComparator;
081
082  /**
083   * Creates an empty {@code TreeMultimap} ordered by the natural ordering of its keys and values.
084   */
085  @SuppressWarnings("rawtypes") // https://github.com/google/guava/issues/989
086  public static <K extends Comparable, V extends Comparable> TreeMultimap<K, V> create() {
087    return new TreeMultimap<>(Ordering.natural(), Ordering.natural());
088  }
089
090  /**
091   * Creates an empty {@code TreeMultimap} instance using explicit comparators. Neither comparator
092   * may be null; use {@link Ordering#natural()} to specify natural order.
093   *
094   * @param keyComparator the comparator that determines the key ordering
095   * @param valueComparator the comparator that determines the value ordering
096   */
097  public static <K extends @Nullable Object, V extends @Nullable Object> TreeMultimap<K, V> create(
098      Comparator<? super K> keyComparator, Comparator<? super V> valueComparator) {
099    return new TreeMultimap<>(checkNotNull(keyComparator), checkNotNull(valueComparator));
100  }
101
102  /**
103   * Constructs a {@code TreeMultimap}, ordered by the natural ordering of its keys and values, with
104   * the same mappings as the specified multimap.
105   *
106   * @param multimap the multimap whose contents are copied to this multimap
107   */
108  @SuppressWarnings("rawtypes") // https://github.com/google/guava/issues/989
109  public static <K extends Comparable, V extends Comparable> TreeMultimap<K, V> create(
110      Multimap<? extends K, ? extends V> multimap) {
111    return new TreeMultimap<>(Ordering.natural(), Ordering.natural(), multimap);
112  }
113
114  TreeMultimap(Comparator<? super K> keyComparator, Comparator<? super V> valueComparator) {
115    super(new TreeMap<K, Collection<V>>(keyComparator));
116    this.keyComparator = keyComparator;
117    this.valueComparator = valueComparator;
118  }
119
120  private TreeMultimap(
121      Comparator<? super K> keyComparator,
122      Comparator<? super V> valueComparator,
123      Multimap<? extends K, ? extends V> multimap) {
124    this(keyComparator, valueComparator);
125    putAll(multimap);
126  }
127
128  @Override
129  Map<K, Collection<V>> createAsMap() {
130    return createMaybeNavigableAsMap();
131  }
132
133  /**
134   * {@inheritDoc}
135   *
136   * <p>Creates an empty {@code TreeSet} for a collection of values for one key.
137   *
138   * @return a new {@code TreeSet} containing a collection of values for one key
139   */
140  @Override
141  SortedSet<V> createCollection() {
142    return new TreeSet<>(valueComparator);
143  }
144
145  @Override
146  Collection<V> createCollection(@ParametricNullness K key) {
147    if (key == null) {
148      int unused = keyComparator().compare(key, key);
149    }
150    return super.createCollection(key);
151  }
152
153  /**
154   * Returns the comparator that orders the multimap keys.
155   *
156   * @deprecated Use {@code ((NavigableSet<K>) multimap.keySet()).comparator()} instead.
157   */
158  @Deprecated
159  public Comparator<? super K> keyComparator() {
160    return keyComparator;
161  }
162
163  @Override
164  public Comparator<? super V> valueComparator() {
165    return valueComparator;
166  }
167
168  /** @since 14.0 (present with return type {@code SortedSet} since 2.0) */
169  @Override
170  @GwtIncompatible // NavigableSet
171  public NavigableSet<V> get(@ParametricNullness K key) {
172    return (NavigableSet<V>) super.get(key);
173  }
174
175  /**
176   * {@inheritDoc}
177   *
178   * <p>Because a {@code TreeMultimap} has unique sorted keys, this method returns a {@link
179   * NavigableSet}, instead of the {@link java.util.Set} specified in the {@link Multimap}
180   * interface.
181   *
182   * @since 14.0 (present with return type {@code SortedSet} since 2.0)
183   */
184  @Override
185  public NavigableSet<K> keySet() {
186    return (NavigableSet<K>) super.keySet();
187  }
188
189  /**
190   * {@inheritDoc}
191   *
192   * <p>Because a {@code TreeMultimap} has unique sorted keys, this method returns a {@link
193   * NavigableMap}, instead of the {@link java.util.Map} specified in the {@link Multimap}
194   * interface.
195   *
196   * @since 14.0 (present with return type {@code SortedMap} since 2.0)
197   */
198  @Override
199  public NavigableMap<K, Collection<V>> asMap() {
200    return (NavigableMap<K, Collection<V>>) super.asMap();
201  }
202
203  /**
204   * @serialData key comparator, value comparator, number of distinct keys, and then for each
205   *     distinct key: the key, number of values for that key, and key values
206   */
207  @GwtIncompatible // java.io.ObjectOutputStream
208  @J2ktIncompatible
209  private void writeObject(ObjectOutputStream stream) throws IOException {
210    stream.defaultWriteObject();
211    stream.writeObject(keyComparator());
212    stream.writeObject(valueComparator());
213    Serialization.writeMultimap(this, stream);
214  }
215
216  @GwtIncompatible // java.io.ObjectInputStream
217  @J2ktIncompatible
218  @SuppressWarnings("unchecked") // reading data stored by writeObject
219  private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException {
220    stream.defaultReadObject();
221    keyComparator = requireNonNull((Comparator<? super K>) stream.readObject());
222    valueComparator = requireNonNull((Comparator<? super V>) stream.readObject());
223    setMap(new TreeMap<K, Collection<V>>(keyComparator));
224    Serialization.populateMultimap(this, stream);
225  }
226
227  @GwtIncompatible // not needed in emulated source
228  @J2ktIncompatible
229  private static final long serialVersionUID = 0;
230}