    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    }