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     * @author Jared Levy
068     * @since 2.0 (imported from Google Collections Library)
069     */
070    @GwtCompatible(serializable = true, emulated = true)
071    public class TreeMultimap<K, V> extends AbstractSortedSetMultimap<K, V> {
072      private transient Comparator<? super K> keyComparator;
073      private transient Comparator<? super V> valueComparator;
074    
075      /**
076       * Creates an empty {@code TreeMultimap} ordered by the natural ordering of
077       * its keys and values.
078       */
079      public static <K extends Comparable, V extends Comparable>
080          TreeMultimap<K, V> create() {
081        return new TreeMultimap<K, V>(Ordering.natural(), Ordering.natural());
082      }
083    
084      /**
085       * Creates an empty {@code TreeMultimap} instance using explicit comparators.
086       * Neither comparator may be null; use {@link Ordering#natural()} to specify
087       * natural order.
088       *
089       * @param keyComparator the comparator that determines the key ordering
090       * @param valueComparator the comparator that determines the value ordering
091       */
092      public static <K, V> TreeMultimap<K, V> create(
093          Comparator<? super K> keyComparator,
094          Comparator<? super V> valueComparator) {
095        return new TreeMultimap<K, V>(checkNotNull(keyComparator),
096            checkNotNull(valueComparator));
097      }
098    
099      /**
100       * Constructs a {@code TreeMultimap}, ordered by the natural ordering of its
101       * keys and values, with the same mappings as the specified multimap.
102       *
103       * @param multimap the multimap whose contents are copied to this multimap
104       */
105      public static <K extends Comparable, V extends Comparable>
106          TreeMultimap<K, V> create(Multimap<? extends K, ? extends V> multimap) {
107        return new TreeMultimap<K, V>(Ordering.natural(), Ordering.natural(),
108            multimap);
109      }
110    
111      TreeMultimap(Comparator<? super K> keyComparator,
112          Comparator<? super V> valueComparator) {
113        super(new TreeMap<K, Collection<V>>(keyComparator));
114        this.keyComparator = keyComparator;
115        this.valueComparator = valueComparator;
116      }
117    
118      private TreeMultimap(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      /**
126       * {@inheritDoc}
127       *
128       * <p>Creates an empty {@code TreeSet} for a collection of values for one key.
129       *
130       * @return a new {@code TreeSet} containing a collection of values for one
131       *     key
132       */
133      @Override SortedSet<V> createCollection() {
134        return new TreeSet<V>(valueComparator);
135      }
136    
137      /**
138       * Returns the comparator that orders the multimap keys.
139       */
140      public Comparator<? super K> keyComparator() {
141        return keyComparator;
142      }
143    
144      @Override
145      public Comparator<? super V> valueComparator() {
146        return valueComparator;
147      }
148    
149      /**
150       * {@inheritDoc}
151       *
152       * <p>Because a {@code TreeMultimap} has unique sorted keys, this method
153       * returns a {@link SortedSet}, instead of the {@link java.util.Set} specified
154       * in the {@link Multimap} interface.
155       */
156      @Override public SortedSet<K> keySet() {
157        return (SortedSet<K>) super.keySet();
158      }
159    
160      /**
161       * {@inheritDoc}
162       *
163       * <p>Because a {@code TreeMultimap} has unique sorted keys, this method
164       * returns a {@link SortedMap}, instead of the {@link java.util.Map} specified
165       * in the {@link Multimap} interface.
166       */
167      @Override public SortedMap<K, Collection<V>> asMap() {
168        return (SortedMap<K, Collection<V>>) super.asMap();
169      }
170    
171      /**
172       * @serialData key comparator, value comparator, number of distinct keys, and
173       *     then for each distinct key: the key, number of values for that key, and
174       *     key values
175       */
176      @GwtIncompatible("java.io.ObjectOutputStream")
177      private void writeObject(ObjectOutputStream stream) throws IOException {
178        stream.defaultWriteObject();
179        stream.writeObject(keyComparator());
180        stream.writeObject(valueComparator());
181        Serialization.writeMultimap(this, stream);
182      }
183    
184      @GwtIncompatible("java.io.ObjectInputStream")
185      @SuppressWarnings("unchecked") // reading data stored by writeObject
186      private void readObject(ObjectInputStream stream)
187          throws IOException, ClassNotFoundException {
188        stream.defaultReadObject();
189        keyComparator = checkNotNull((Comparator<? super K>) stream.readObject());
190        valueComparator = checkNotNull((Comparator<? super V>) stream.readObject());
191        setMap(new TreeMap<K, Collection<V>>(keyComparator));
192        Serialization.populateMultimap(this, stream);
193      }
194    
195      @GwtIncompatible("not needed in emulated source")
196      private static final long serialVersionUID = 0;
197    }