001 /*
002 * Copyright (C) 2007 Google Inc.
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
017 package com.google.common.collect;
018
019 import static com.google.common.base.Preconditions.checkNotNull;
020
021 import com.google.common.annotations.GwtCompatible;
022 import com.google.common.annotations.GwtIncompatible;
023
024 import java.io.IOException;
025 import java.io.ObjectInputStream;
026 import java.io.ObjectOutputStream;
027 import java.util.Collection;
028 import java.util.Comparator;
029 import java.util.Set;
030 import java.util.SortedMap;
031 import java.util.SortedSet;
032 import java.util.TreeMap;
033 import java.util.TreeSet;
034
035 /**
036 * Implementation of {@code Multimap} whose keys and values are ordered by
037 * their natural ordering or by supplied comparators. In all cases, this
038 * implementation uses {@link Comparable#compareTo} or {@link
039 * Comparator#compare} instead of {@link Object#equals} to determine
040 * equivalence of instances.
041 *
042 * <p><b>Warning:</b> The comparators or comparables used must be <i>consistent
043 * with equals</i> as explained by the {@link Comparable} class specification.
044 * Otherwise, the resulting multiset will violate the general contract of {@link
045 * SetMultimap}, which it is specified in terms of {@link Object#equals}.
046 *
047 * <p>The collections returned by {@code keySet} and {@code asMap} iterate
048 * through the keys according to the key comparator ordering or the natural
049 * ordering of the keys. Similarly, {@code get}, {@code removeAll}, and {@code
050 * replaceValues} return collections that iterate through the values according
051 * to the value comparator ordering or the natural ordering of the values. The
052 * collections generated by {@code entries}, {@code keys}, and {@code values}
053 * iterate across the keys according to the above key ordering, and for each
054 * key they iterate across the values according to the value ordering.
055 *
056 * <p>The multimap does not store duplicate key-value pairs. Adding a new
057 * key-value pair equal to an existing key-value pair has no effect.
058 *
059 * <p>Depending on the comparators, null keys and values may or may not be
060 * supported. The natural ordering does not support nulls. All optional multimap
061 * methods are supported, and all returned views are modifiable.
062 *
063 * <p>This class is not threadsafe when any concurrent operations update the
064 * multimap. Concurrent read operations will work correctly. To allow concurrent
065 * update operations, wrap your multimap with a call to {@link
066 * Multimaps#synchronizedSortedSetMultimap}.
067 *
068 * @author Jared Levy
069 * @since 2 (imported from Google Collections Library)
070 */
071 @GwtCompatible(serializable = true, emulated = true)
072 public class TreeMultimap<K, V> extends AbstractSortedSetMultimap<K, V> {
073 private transient Comparator<? super K> keyComparator;
074 private transient Comparator<? super V> valueComparator;
075
076 /**
077 * Creates an empty {@code TreeMultimap} ordered by the natural ordering of
078 * its keys and values.
079 */
080 @SuppressWarnings("unchecked") // eclipse doesn't like the raw Comparable
081 public static <K extends Comparable, V extends Comparable>
082 TreeMultimap<K, V> create() {
083 return new TreeMultimap<K, V>(Ordering.natural(), Ordering.natural());
084 }
085
086 /**
087 * Creates an empty {@code TreeMultimap} instance using explicit comparators.
088 * Neither comparator may be null; use {@link Ordering#natural()} to specify
089 * 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, V> TreeMultimap<K, V> create(
095 Comparator<? super K> keyComparator,
096 Comparator<? super V> valueComparator) {
097 return new TreeMultimap<K, V>(checkNotNull(keyComparator),
098 checkNotNull(valueComparator));
099 }
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 @SuppressWarnings("unchecked") // eclipse doesn't like the raw Comparable
108 public static <K extends Comparable, V extends Comparable>
109 TreeMultimap<K, V> create(Multimap<? extends K, ? extends V> multimap) {
110 return new TreeMultimap<K, V>(Ordering.natural(), Ordering.natural(),
111 multimap);
112 }
113
114 TreeMultimap(Comparator<? super K> keyComparator,
115 Comparator<? super V> valueComparator) {
116 super(new TreeMap<K, Collection<V>>(keyComparator));
117 this.keyComparator = keyComparator;
118 this.valueComparator = valueComparator;
119 }
120
121 private TreeMultimap(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 /**
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
134 * key
135 */
136 @Override SortedSet<V> createCollection() {
137 return new TreeSet<V>(valueComparator);
138 }
139
140 /**
141 * Returns the comparator that orders the multimap keys.
142 */
143 public Comparator<? super K> keyComparator() {
144 return keyComparator;
145 }
146
147 public Comparator<? super V> valueComparator() {
148 return valueComparator;
149 }
150
151 /**
152 * {@inheritDoc}
153 *
154 * <p>Because a {@code TreeMultimap} has unique sorted keys, this method
155 * returns a {@link SortedSet}, instead of the {@link Set} specified in the
156 * {@link Multimap} interface.
157 */
158 @Override public SortedSet<K> keySet() {
159 return (SortedSet<K>) super.keySet();
160 }
161
162 /**
163 * {@inheritDoc}
164 *
165 * <p>Because a {@code TreeMultimap} has unique sorted keys, this method
166 * returns a {@link SortedMap}, instead of the {@link java.util.Map} specified
167 * in the {@link Multimap} interface.
168 */
169 @Override public SortedMap<K, Collection<V>> asMap() {
170 return (SortedMap<K, Collection<V>>) super.asMap();
171 }
172
173 /**
174 * @serialData key comparator, value comparator, number of distinct keys, and
175 * then for each distinct key: the key, number of values for that key, and
176 * key values
177 */
178 @GwtIncompatible("java.io.ObjectOutputStream")
179 private void writeObject(ObjectOutputStream stream) throws IOException {
180 stream.defaultWriteObject();
181 stream.writeObject(keyComparator());
182 stream.writeObject(valueComparator());
183 Serialization.writeMultimap(this, stream);
184 }
185
186 @GwtIncompatible("java.io.ObjectInputStream")
187 @SuppressWarnings("unchecked") // reading data stored by writeObject
188 private void readObject(ObjectInputStream stream)
189 throws IOException, ClassNotFoundException {
190 stream.defaultReadObject();
191 keyComparator = checkNotNull((Comparator<? super K>) stream.readObject());
192 valueComparator = checkNotNull((Comparator<? super V>) stream.readObject());
193 setMap(new TreeMap<K, Collection<V>>(keyComparator));
194 Serialization.populateMultimap(this, stream);
195 }
196
197 @GwtIncompatible("not needed in emulated source")
198 private static final long serialVersionUID = 0;
199 }