1/*
2 * Copyright (C) 2007 The Guava Authors
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package com.google.common.collect;
18
19import static com.google.common.base.Preconditions.checkNotNull;
20
21import com.google.common.annotations.GwtCompatible;
22
23import java.util.Collection;
24import java.util.Comparator;
25import java.util.SortedSet;
26import java.util.TreeMap;
27import java.util.TreeSet;
28
29import javax.annotation.Nullable;
30
31/**
32 * Implementation of {@code Multimap} whose keys and values are ordered by
33 * their natural ordering or by supplied comparators. In all cases, this
34 * implementation uses {@link Comparable#compareTo} or {@link
35 * Comparator#compare} instead of {@link Object#equals} to determine
36 * equivalence of instances.
37 *
38 * <p><b>Warning:</b> The comparators or comparables used must be <i>consistent
39 * with equals</i> as explained by the {@link Comparable} class specification.
40 * Otherwise, the resulting multiset will violate the general contract of {@link
41 * SetMultimap}, which it is specified in terms of {@link Object#equals}.
42 *
43 * <p>The collections returned by {@code keySet} and {@code asMap} iterate
44 * through the keys according to the key comparator ordering or the natural
45 * ordering of the keys. Similarly, {@code get}, {@code removeAll}, and {@code
46 * replaceValues} return collections that iterate through the values according
47 * to the value comparator ordering or the natural ordering of the values. The
48 * collections generated by {@code entries}, {@code keys}, and {@code values}
49 * iterate across the keys according to the above key ordering, and for each
50 * key they iterate across the values according to the value ordering.
51 *
52 * <p>The multimap does not store duplicate key-value pairs. Adding a new
53 * key-value pair equal to an existing key-value pair has no effect.
54 *
55 * <p>Null keys and values are permitted (provided, of course, that the
56 * respective comparators support them). All optional multimap methods are
57 * supported, and all returned views are modifiable.
58 *
59 * <p>This class is not threadsafe when any concurrent operations update the
60 * multimap. Concurrent read operations will work correctly. To allow concurrent
61 * update operations, wrap your multimap with a call to {@link
62 * Multimaps#synchronizedSortedSetMultimap}.
63 *
64 * <p>See the Guava User Guide article on <a href=
65 * "http://code.google.com/p/guava-libraries/wiki/NewCollectionTypesExplained#Multimap">
66 * {@code Multimap}</a>.
67 *
68 * @author Jared Levy
69 * @author Louis Wasserman
70 * @since 2.0 (imported from Google Collections Library)
71 */
72@GwtCompatible(serializable = true, emulated = true)
73public class TreeMultimap<K, V> extends AbstractSortedKeySortedSetMultimap<K, V> {
74  private transient Comparator<? super K> keyComparator;
75  private transient Comparator<? super V> valueComparator;
76
77  /**
78   * Creates an empty {@code TreeMultimap} ordered by the natural ordering of
79   * its keys and values.
80   */
81  public static <K extends Comparable, V extends Comparable>
82      TreeMultimap<K, V> create() {
83    return new TreeMultimap<K, V>(Ordering.natural(), Ordering.natural());
84  }
85
86  /**
87   * Creates an empty {@code TreeMultimap} instance using explicit comparators.
88   * Neither comparator may be null; use {@link Ordering#natural()} to specify
89   * natural order.
90   *
91   * @param keyComparator the comparator that determines the key ordering
92   * @param valueComparator the comparator that determines the value ordering
93   */
94  public static <K, V> TreeMultimap<K, V> create(
95      Comparator<? super K> keyComparator,
96      Comparator<? super V> valueComparator) {
97    return new TreeMultimap<K, V>(checkNotNull(keyComparator),
98        checkNotNull(valueComparator));
99  }
100
101  /**
102   * Constructs a {@code TreeMultimap}, ordered by the natural ordering of its
103   * keys and values, with the same mappings as the specified multimap.
104   *
105   * @param multimap the multimap whose contents are copied to this multimap
106   */
107  public static <K extends Comparable, V extends Comparable>
108      TreeMultimap<K, V> create(Multimap<? extends K, ? extends V> multimap) {
109    return new TreeMultimap<K, V>(Ordering.natural(), Ordering.natural(),
110        multimap);
111  }
112
113  TreeMultimap(Comparator<? super K> keyComparator,
114      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(Comparator<? super K> keyComparator,
121      Comparator<? super V> valueComparator,
122      Multimap<? extends K, ? extends V> multimap) {
123    this(keyComparator, valueComparator);
124    putAll(multimap);
125  }
126
127  /**
128   * {@inheritDoc}
129   *
130   * <p>Creates an empty {@code TreeSet} for a collection of values for one key.
131   *
132   * @return a new {@code TreeSet} containing a collection of values for one
133   *     key
134   */
135  @Override SortedSet<V> createCollection() {
136    return new TreeSet<V>(valueComparator);
137  }
138
139  @Override
140  Collection<V> createCollection(@Nullable K key) {
141    if (key == null) {
142      keyComparator().compare(key, key);
143    }
144    return super.createCollection(key);
145  }
146
147  /**
148   * Returns the comparator that orders the multimap keys.
149   */
150  public Comparator<? super K> keyComparator() {
151    return keyComparator;
152  }
153
154  @Override
155  public Comparator<? super V> valueComparator() {
156    return valueComparator;
157  }
158
159  /*
160   * The following @GwtIncompatible methods override the methods in
161   * AbstractSortedKeySortedSetMultimap, so GWT will fall back to the ASKSSM implementations,
162   * which return SortedSets and SortedMaps.
163   */
164}
165
166