    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    }