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