    001    /*
    002     * Copyright (C) 2009 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.Beta;
    022    import com.google.common.annotations.GwtCompatible;
    023    import com.google.common.annotations.GwtIncompatible;
    024    import com.google.common.base.Function;
    025
    026    import java.io.IOException;
    027    import java.io.InvalidObjectException;
    028    import java.io.ObjectInputStream;
    029    import java.io.ObjectOutputStream;
    030    import java.util.Arrays;
    031    import java.util.Collection;
    032    import java.util.Collections;
    033    import java.util.Comparator;
    034    import java.util.LinkedHashMap;
    035    import java.util.List;
    036    import java.util.Map;
    037    import java.util.Map.Entry;
    038    import java.util.TreeMap;
    039
    040    import javax.annotation.Nullable;
    041
    042    /**
    043     * An immutable {@link SetMultimap} with reliable user-specified key and value
    044     * iteration order. Does not permit null keys or values.
    045     *
    046     * <p>Unlike {@link Multimaps#unmodifiableSetMultimap(SetMultimap)}, which is
    047     * a <i>view</i> of a separate multimap which can still change, an instance of
    048     * {@code ImmutableSetMultimap} contains its own data and will <i>never</i>
    049     * change. {@code ImmutableSetMultimap} is convenient for
    050     * {@code public static final} multimaps ("constant multimaps") and also lets
    051     * you easily make a "defensive copy" of a multimap provided to your class by
    052     * a caller.
    053     *
    054     * <p><b>Note:</b> Although this class is not final, it cannot be subclassed as
    055     * it has no public or protected constructors. Thus, instances of this class
    056     * are guaranteed to be immutable.
    057     *
    058     * <p>See the Guava User Guide article on <a href=
    059     * "http://code.google.com/p/guava-libraries/wiki/ImmutableCollectionsExplained">
    060     * immutable collections</a>.
    061     *
    062     * @author Mike Ward
    063     * @since 2.0 (imported from Google Collections Library)
    064     */
    065    @GwtCompatible(serializable = true, emulated = true)
    066    public class ImmutableSetMultimap<K, V>
    067        extends ImmutableMultimap<K, V>
    068        implements SetMultimap<K, V> {
    069
    070      /** Returns the empty multimap. */
    071      // Casting is safe because the multimap will never hold any elements.
    072      @SuppressWarnings("unchecked")
    073      public static <K, V> ImmutableSetMultimap<K, V> of() {
    074        return (ImmutableSetMultimap<K, V>) EmptyImmutableSetMultimap.INSTANCE;
    075      }
    076
    077      /**
    078       * Returns an immutable multimap containing a single entry.
    079       */
    080      public static <K, V> ImmutableSetMultimap<K, V> of(K k1, V v1) {
    081        ImmutableSetMultimap.Builder<K, V> builder = ImmutableSetMultimap.builder();
    082        builder.put(k1, v1);
    083        return builder.build();
    084      }
    085
    086      /**
    087       * Returns an immutable multimap containing the given entries, in order.
    088       * Repeated occurrences of an entry (according to {@link Object#equals}) after
    089       * the first are ignored.
    090       */
    091      public static <K, V> ImmutableSetMultimap<K, V> of(K k1, V v1, K k2, V v2) {
    092        ImmutableSetMultimap.Builder<K, V> builder = ImmutableSetMultimap.builder();
    093        builder.put(k1, v1);
    094        builder.put(k2, v2);
    095        return builder.build();
    096      }
    097
    098      /**
    099       * Returns an immutable multimap containing the given entries, in order.
    100       * Repeated occurrences of an entry (according to {@link Object#equals}) after
    101       * the first are ignored.
    102       */
    103      public static <K, V> ImmutableSetMultimap<K, V> of(
    104          K k1, V v1, K k2, V v2, K k3, V v3) {
    105        ImmutableSetMultimap.Builder<K, V> builder = ImmutableSetMultimap.builder();
    106        builder.put(k1, v1);
    107        builder.put(k2, v2);
    108        builder.put(k3, v3);
    109        return builder.build();
    110      }
    111
    112      /**
    113       * Returns an immutable multimap containing the given entries, in order.
    114       * Repeated occurrences of an entry (according to {@link Object#equals}) after
    115       * the first are ignored.
    116       */
    117      public static <K, V> ImmutableSetMultimap<K, V> of(
    118          K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4) {
    119        ImmutableSetMultimap.Builder<K, V> builder = ImmutableSetMultimap.builder();
    120        builder.put(k1, v1);
    121        builder.put(k2, v2);
    122        builder.put(k3, v3);
    123        builder.put(k4, v4);
    124        return builder.build();
    125      }
    126
    127      /**
    128       * Returns an immutable multimap containing the given entries, in order.
    129       * Repeated occurrences of an entry (according to {@link Object#equals}) after
    130       * the first are ignored.
    131       */
    132      public static <K, V> ImmutableSetMultimap<K, V> of(
    133          K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5) {
    134        ImmutableSetMultimap.Builder<K, V> builder = ImmutableSetMultimap.builder();
    135        builder.put(k1, v1);
    136        builder.put(k2, v2);
    137        builder.put(k3, v3);
    138        builder.put(k4, v4);
    139        builder.put(k5, v5);
    140        return builder.build();
    141      }
    142
    143      // looking for of() with > 5 entries? Use the builder instead.
    144
    145      /**
    146       * Returns a new {@link Builder}.
    147       */
    148      public static <K, V> Builder<K, V> builder() {
    149        return new Builder<K, V>();
    150      }
    151
    152      /**
    153       * Multimap for {@link ImmutableSetMultimap.Builder} that maintains key
    154       * and value orderings and performs better than {@link LinkedHashMultimap}.
    155       */
    156      private static class BuilderMultimap<K, V> extends AbstractMultimap<K, V> {
    157        BuilderMultimap() {
    158          super(new LinkedHashMap<K, Collection<V>>());
    159        }
    160        @Override Collection<V> createCollection() {
    161          return Sets.newLinkedHashSet();
    162        }
    163        private static final long serialVersionUID = 0;
    164      }
    165
    166      /**
    167       * Multimap for {@link ImmutableSetMultimap.Builder} that sorts keys and
    168       * maintains value orderings.
    169       */
    170      private static class SortedKeyBuilderMultimap<K, V>
    171          extends AbstractMultimap<K, V> {
    172        SortedKeyBuilderMultimap(
    173            Comparator<? super K> keyComparator, Multimap<K, V> multimap) {
    174          super(new TreeMap<K, Collection<V>>(keyComparator));
    175          putAll(multimap);
    176        }
    177        @Override Collection<V> createCollection() {
    178          return Sets.newLinkedHashSet();
    179        }
    180        private static final long serialVersionUID = 0;
    181      }
    182
    183      /**
    184       * A builder for creating immutable {@code SetMultimap} instances, especially
    185       * {@code public static final} multimaps ("constant multimaps"). Example:
    186       * <pre>   {@code
    187       *
    188       *   static final Multimap<String, Integer> STRING_TO_INTEGER_MULTIMAP =
    189       *       new ImmutableSetMultimap.Builder<String, Integer>()
    190       *           .put("one", 1)
    191       *           .putAll("several", 1, 2, 3)
    192       *           .putAll("many", 1, 2, 3, 4, 5)
    193       *           .build();}</pre>
    194       *
    195       * Builder instances can be reused; it is safe to call {@link #build} multiple
    196       * times to build multiple multimaps in series. Each multimap contains the
    197       * key-value mappings in the previously created multimaps.
    198       *
    199       * @since 2.0 (imported from Google Collections Library)
    200       */
    201      public static final class Builder<K, V>
    202          extends ImmutableMultimap.Builder<K, V> {
    203        /**
    204         * Creates a new builder. The returned builder is equivalent to the builder
    205         * generated by {@link ImmutableSetMultimap#builder}.
    206         */
    207        public Builder() {
    208          builderMultimap = new BuilderMultimap<K, V>();
    209        }
    210
    211        /**
    212         * Adds a key-value mapping to the built multimap if it is not already
    213         * present.
    214         */
    215        @Override public Builder<K, V> put(K key, V value) {
    216          builderMultimap.put(checkNotNull(key), checkNotNull(value));
    217          return this;
    218        }
    219
    220        /**
    221         * Adds an entry to the built multimap if it is not already present.
    222         *
    223         * @since 11.0
    224         */
    225        @Override public Builder<K, V> put(Entry<? extends K, ? extends V> entry) {
    226          builderMultimap.put(
    227              checkNotNull(entry.getKey()), checkNotNull(entry.getValue()));
    228          return this;
    229        }
    230
    231        @Override public Builder<K, V> putAll(K key, Iterable<? extends V> values) {
    232          Collection<V> collection = builderMultimap.get(checkNotNull(key));
    233          for (V value : values) {
    234            collection.add(checkNotNull(value));
    235          }
    236          return this;
    237        }
    238
    239        @Override public Builder<K, V> putAll(K key, V... values) {
    240          return putAll(key, Arrays.asList(values));
    241        }
    242
    243        @Override public Builder<K, V> putAll(
    244            Multimap<? extends K, ? extends V> multimap) {
    245          for (Entry<? extends K, ? extends Collection<? extends V>> entry
    246              : multimap.asMap().entrySet()) {
    247            putAll(entry.getKey(), entry.getValue());
    248          }
    249          return this;
    250        }
    251
    252        /**
    253         * {@inheritDoc}
    254         *
    255         * @since 8.0
    256         */
    257        @Beta @Override
    258        public Builder<K, V> orderKeysBy(Comparator<? super K> keyComparator) {
    259          this.keyComparator = checkNotNull(keyComparator);
    260          return this;
    261        }
    262
    263        /**
    264         * Specifies the ordering of the generated multimap's values for each key.
    265         *
    266         * <p>If this method is called, the sets returned by the {@code get()}
    267         * method of the generated multimap and its {@link Multimap#asMap()} view
    268         * are {@link ImmutableSortedSet} instances. However, serialization does not
    269         * preserve that property, though it does maintain the key and value
    270         * ordering.
    271         *
    272         * @since 8.0
    273         */
    274        // TODO: Make serialization behavior consistent.
    275        @Beta @Override
    276        public Builder<K, V> orderValuesBy(Comparator<? super V> valueComparator) {
    277          super.orderValuesBy(valueComparator);
    278          return this;
    279        }
    280
    281        /**
    282         * Returns a newly-created immutable set multimap.
    283         */
    284        @Override public ImmutableSetMultimap<K, V> build() {
    285          if (keyComparator != null) {
    286            Multimap<K, V> sortedCopy = new BuilderMultimap<K, V>();
    287            List<Map.Entry<K, Collection<V>>> entries = Lists.newArrayList(
    288                builderMultimap.asMap().entrySet());
    289            Collections.sort(
    290                entries,
    291                Ordering.from(keyComparator).onResultOf(new Function<Entry<K, Collection<V>>, K>() {
    292                  @Override
    293                  public K apply(Entry<K, Collection<V>> entry) {
    294                    return entry.getKey();
    295                  }
    296                }));
    297            for (Map.Entry<K, Collection<V>> entry : entries) {
    298              sortedCopy.putAll(entry.getKey(), entry.getValue());
    299            }
    300            builderMultimap = sortedCopy;
    301          }
    302          return copyOf(builderMultimap, valueComparator);
    303        }
    304      }
    305
    306      /**
    307       * Returns an immutable set multimap containing the same mappings as
    308       * {@code multimap}. The generated multimap's key and value orderings
    309       * correspond to the iteration ordering of the {@code multimap.asMap()} view.
    310       * Repeated occurrences of an entry in the multimap after the first are
    311       * ignored.
    312       *
    313       * <p>Despite the method name, this method attempts to avoid actually copying
    314       * the data when it is safe to do so. The exact circumstances under which a
    315       * copy will or will not be performed are undocumented and subject to change.
    316       *
    317       * @throws NullPointerException if any key or value in {@code multimap} is
    318       *     null
    319       */
    320      public static <K, V> ImmutableSetMultimap<K, V> copyOf(
    321          Multimap<? extends K, ? extends V> multimap) {
    322        return copyOf(multimap, null);
    323      }
    324
    325      private static <K, V> ImmutableSetMultimap<K, V> copyOf(
    326          Multimap<? extends K, ? extends V> multimap,
    327          Comparator<? super V> valueComparator) {
    328        checkNotNull(multimap); // eager for GWT
    329        if (multimap.isEmpty() && valueComparator == null) {
    330          return of();
    331        }
    332
    333        if (multimap instanceof ImmutableSetMultimap) {
    334          @SuppressWarnings("unchecked") // safe since multimap is not writable
    335          ImmutableSetMultimap<K, V> kvMultimap
    336              = (ImmutableSetMultimap<K, V>) multimap;
    337          if (!kvMultimap.isPartialView()) {
    338            return kvMultimap;
    339          }
    340        }
    341
    342        ImmutableMap.Builder<K, ImmutableSet<V>> builder = ImmutableMap.builder();
    343        int size = 0;
    344
    345        for (Entry<? extends K, ? extends Collection<? extends V>> entry
    346            : multimap.asMap().entrySet()) {
    347          K key = entry.getKey();
    348          Collection<? extends V> values = entry.getValue();
    349          ImmutableSet<V> set = (valueComparator == null)
    350              ? ImmutableSet.copyOf(values)
    351              : ImmutableSortedSet.copyOf(valueComparator, values);
    352          if (!set.isEmpty()) {
    353            builder.put(key, set);
    354            size += set.size();
    355          }
    356        }
    357
    358        return new ImmutableSetMultimap<K, V>(
    359            builder.build(), size, valueComparator);
    360      }
    361
    362      // Returned by get() when values are sorted and a missing key is provided.
    363      private final transient ImmutableSortedSet<V> emptySet;
    364
    365      ImmutableSetMultimap(ImmutableMap<K, ImmutableSet<V>> map, int size,
    366          @Nullable Comparator<? super V> valueComparator) {
    367        super(map, size);
    368        this.emptySet = (valueComparator == null)
    369            ? null : ImmutableSortedSet.<V>emptySet(valueComparator);
    370      }
    371
    372      // views
    373
    374      /**
    375       * Returns an immutable set of the values for the given key.  If no mappings
    376       * in the multimap have the provided key, an empty immutable set is returned.
    377       * The values are in the same order as the parameters used to build this
    378       * multimap.
    379       */
    380      @Override public ImmutableSet<V> get(@Nullable K key) {
    381        // This cast is safe as its type is known in constructor.
    382        ImmutableSet<V> set = (ImmutableSet<V>) map.get(key);
    383        if (set != null) {
    384          return set;
    385        } else if (emptySet != null) {
    386          return emptySet;
    387        } else {
    388          return ImmutableSet.<V>of();
    389        }
    390      }
    391
    392      private transient ImmutableSetMultimap<V, K> inverse;
    393
    394      /**
    395       * {@inheritDoc}
    396       *
    397       * <p>Because an inverse of a set multimap cannot contain multiple pairs with
    398       * the same key and value, this method returns an {@code ImmutableSetMultimap}
    399       * rather than the {@code ImmutableMultimap} specified in the {@code
    400       * ImmutableMultimap} class.
    401       *
    402       * @since 11.0
    403       */
    404      @Beta
    405      public ImmutableSetMultimap<V, K> inverse() {
    406        ImmutableSetMultimap<V, K> result = inverse;
    407        return (result == null) ? (inverse = invert()) : result;
    408      }
    409
    410      private ImmutableSetMultimap<V, K> invert() {
    411        Builder<V, K> builder = builder();
    412        for (Entry<K, V> entry : entries()) {
    413          builder.put(entry.getValue(), entry.getKey());
    414        }
    415        ImmutableSetMultimap<V, K> invertedMultimap = builder.build();
    416        invertedMultimap.inverse = this;
    417        return invertedMultimap;
    418      }
    419
    420      /**
    421       * Guaranteed to throw an exception and leave the multimap unmodified.
    422       *
    423       * @throws UnsupportedOperationException always
    424       */
    425      @Override public ImmutableSet<V> removeAll(Object key) {
    426        throw new UnsupportedOperationException();
    427      }
    428
    429      /**
    430       * Guaranteed to throw an exception and leave the multimap unmodified.
    431       *
    432       * @throws UnsupportedOperationException always
    433       */
    434      @Override public ImmutableSet<V> replaceValues(
    435          K key, Iterable<? extends V> values) {
    436        throw new UnsupportedOperationException();
    437      }
    438
    439      private transient ImmutableSet<Entry<K, V>> entries;
    440
    441      /**
    442       * Returns an immutable collection of all key-value pairs in the multimap.
    443       * Its iterator traverses the values for the first key, the values for the
    444       * second key, and so on.
    445       */
    446      // TODO(kevinb): Fix this so that two copies of the entries are not created.
    447      @Override public ImmutableSet<Entry<K, V>> entries() {
    448        ImmutableSet<Entry<K, V>> result = entries;
    449        return (result == null)
    450            ? (entries = ImmutableSet.copyOf(super.entries()))
    451            : result;
    452      }
    453
    454      /**
    455       * @serialData number of distinct keys, and then for each distinct key: the
    456       *     key, the number of values for that key, and the key's values
    457       */
    458      @GwtIncompatible("java.io.ObjectOutputStream")
    459      private void writeObject(ObjectOutputStream stream) throws IOException {
    460        stream.defaultWriteObject();
    461        Serialization.writeMultimap(this, stream);
    462      }
    463
    464      @GwtIncompatible("java.io.ObjectInputStream")
    465      private void readObject(ObjectInputStream stream)
    466          throws IOException, ClassNotFoundException {
    467        stream.defaultReadObject();
    468        int keyCount = stream.readInt();
    469        if (keyCount < 0) {
    470          throw new InvalidObjectException("Invalid key count " + keyCount);
    471        }
    472        ImmutableMap.Builder<Object, ImmutableSet<Object>> builder
    473            = ImmutableMap.builder();
    474        int tmpSize = 0;
    475
    476        for (int i = 0; i < keyCount; i++) {
    477          Object key = stream.readObject();
    478          int valueCount = stream.readInt();
    479          if (valueCount <= 0) {
    480            throw new InvalidObjectException("Invalid value count " + valueCount);
    481          }
    482
    483          Object[] array = new Object[valueCount];
    484          for (int j = 0; j < valueCount; j++) {
    485            array[j] = stream.readObject();
    486          }
    487          ImmutableSet<Object> valueSet = ImmutableSet.copyOf(array);
    488          if (valueSet.size() != array.length) {
    489            throw new InvalidObjectException(
    490                "Duplicate key-value pairs exist for key " + key);
    491          }
    492          builder.put(key, valueSet);
    493          tmpSize += valueCount;
    494        }
    495
    496        ImmutableMap<Object, ImmutableSet<Object>> tmpMap;
    497        try {
    498          tmpMap = builder.build();
    499        } catch (IllegalArgumentException e) {
    500          throw (InvalidObjectException)
    501              new InvalidObjectException(e.getMessage()).initCause(e);
    502        }
    503
    504        FieldSettersHolder.MAP_FIELD_SETTER.set(this, tmpMap);
    505        FieldSettersHolder.SIZE_FIELD_SETTER.set(this, tmpSize);
    506      }
    507
    508      @GwtIncompatible("not needed in emulated source.")
    509      private static final long serialVersionUID = 0;
    510    }