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