    001    /*
    002     * Copyright (C) 2008 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 com.google.common.annotations.Beta;
    020    import com.google.common.annotations.GwtCompatible;
    021    import com.google.common.annotations.GwtIncompatible;
    022
    023    import java.io.IOException;
    024    import java.io.InvalidObjectException;
    025    import java.io.ObjectInputStream;
    026    import java.io.ObjectOutputStream;
    027    import java.util.Collection;
    028    import java.util.Comparator;
    029    import java.util.Map;
    030
    031    import javax.annotation.Nullable;
    032
    033    /**
    034     * An immutable {@link ListMultimap} with reliable user-specified key and value
    035     * iteration order. Does not permit null keys or values.
    036     *
    037     * <p>Unlike {@link Multimaps#unmodifiableListMultimap(ListMultimap)}, which is
    038     * a <i>view</i> of a separate multimap which can still change, an instance of
    039     * {@code ImmutableListMultimap} contains its own data and will <i>never</i>
    040     * change. {@code ImmutableListMultimap} is convenient for
    041     * {@code public static final} multimaps ("constant multimaps") and also lets
    042     * you easily make a "defensive copy" of a multimap provided to your class by
    043     * a caller.
    044     *
    045     * <p><b>Note:</b> Although this class is not final, it cannot be subclassed as
    046     * it has no public or protected constructors. Thus, instances of this class
    047     * are guaranteed to be immutable.
    048     *
    049     * @author Jared Levy
    050     * @since 2.0 (imported from Google Collections Library)
    051     */
    052    @GwtCompatible(serializable = true, emulated = true)
    053    public class ImmutableListMultimap<K, V>
    054        extends ImmutableMultimap<K, V>
    055        implements ListMultimap<K, V> {
    056
    057      /** Returns the empty multimap. */
    058      // Casting is safe because the multimap will never hold any elements.
    059      @SuppressWarnings("unchecked")
    060      public static <K, V> ImmutableListMultimap<K, V> of() {
    061        return (ImmutableListMultimap<K, V>) EmptyImmutableListMultimap.INSTANCE;
    062      }
    063
    064      /**
    065       * Returns an immutable multimap containing a single entry.
    066       */
    067      public static <K, V> ImmutableListMultimap<K, V> of(K k1, V v1) {
    068        ImmutableListMultimap.Builder<K, V> builder
    069            = ImmutableListMultimap.builder();
    070        builder.put(k1, v1);
    071        return builder.build();
    072      }
    073
    074      /**
    075       * Returns an immutable multimap containing the given entries, in order.
    076       */
    077      public static <K, V> ImmutableListMultimap<K, V> of(K k1, V v1, K k2, V v2) {
    078        ImmutableListMultimap.Builder<K, V> builder
    079            = ImmutableListMultimap.builder();
    080        builder.put(k1, v1);
    081        builder.put(k2, v2);
    082        return builder.build();
    083      }
    084
    085      /**
    086       * Returns an immutable multimap containing the given entries, in order.
    087       */
    088      public static <K, V> ImmutableListMultimap<K, V> of(
    089          K k1, V v1, K k2, V v2, K k3, V v3) {
    090        ImmutableListMultimap.Builder<K, V> builder
    091            = ImmutableListMultimap.builder();
    092        builder.put(k1, v1);
    093        builder.put(k2, v2);
    094        builder.put(k3, v3);
    095        return builder.build();
    096      }
    097
    098      /**
    099       * Returns an immutable multimap containing the given entries, in order.
    100       */
    101      public static <K, V> ImmutableListMultimap<K, V> of(
    102          K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4) {
    103        ImmutableListMultimap.Builder<K, V> builder
    104            = ImmutableListMultimap.builder();
    105        builder.put(k1, v1);
    106        builder.put(k2, v2);
    107        builder.put(k3, v3);
    108        builder.put(k4, v4);
    109        return builder.build();
    110      }
    111
    112      /**
    113       * Returns an immutable multimap containing the given entries, in order.
    114       */
    115      public static <K, V> ImmutableListMultimap<K, V> of(
    116          K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5) {
    117        ImmutableListMultimap.Builder<K, V> builder
    118            = ImmutableListMultimap.builder();
    119        builder.put(k1, v1);
    120        builder.put(k2, v2);
    121        builder.put(k3, v3);
    122        builder.put(k4, v4);
    123        builder.put(k5, v5);
    124        return builder.build();
    125      }
    126
    127      // looking for of() with > 5 entries? Use the builder instead.
    128
    129      /**
    130       * Returns a new builder. The generated builder is equivalent to the builder
    131       * created by the {@link Builder} constructor.
    132       */
    133      public static <K, V> Builder<K, V> builder() {
    134        return new Builder<K, V>();
    135      }
    136
    137      /**
    138       * A builder for creating immutable {@code ListMultimap} instances, especially
    139       * {@code public static final} multimaps ("constant multimaps"). Example:
    140       * <pre>   {@code
    141       *
    142       *   static final Multimap<String, Integer> STRING_TO_INTEGER_MULTIMAP =
    143       *       new ImmutableListMultimap.Builder<String, Integer>()
    144       *           .put("one", 1)
    145       *           .putAll("several", 1, 2, 3)
    146       *           .putAll("many", 1, 2, 3, 4, 5)
    147       *           .build();}</pre>
    148       *
    149       * Builder instances can be reused; it is safe to call {@link #build} multiple
    150       * times to build multiple multimaps in series. Each multimap contains the
    151       * key-value mappings in the previously created multimaps.
    152       *
    153       * @since 2.0 (imported from Google Collections Library)
    154       */
    155      public static final class Builder<K, V>
    156          extends ImmutableMultimap.Builder<K, V> {
    157        /**
    158         * Creates a new builder. The returned builder is equivalent to the builder
    159         * generated by {@link ImmutableListMultimap#builder}.
    160         */
    161        public Builder() {}
    162
    163        @Override public Builder<K, V> put(K key, V value) {
    164          super.put(key, value);
    165          return this;
    166        }
    167
    168        @Override public Builder<K, V> putAll(K key, Iterable<? extends V> values) {
    169          super.putAll(key, values);
    170          return this;
    171        }
    172
    173        @Override public Builder<K, V> putAll(K key, V... values) {
    174          super.putAll(key, values);
    175          return this;
    176        }
    177
    178        @Override public Builder<K, V> putAll(
    179            Multimap<? extends K, ? extends V> multimap) {
    180          super.putAll(multimap);
    181          return this;
    182        }
    183
    184        /**
    185         * {@inheritDoc}
    186         *
    187         * @since 8.0
    188         */
    189        @Beta @Override
    190        public Builder<K, V> orderKeysBy(Comparator<? super K> keyComparator) {
    191          super.orderKeysBy(keyComparator);
    192          return this;
    193        }
    194
    195        /**
    196         * {@inheritDoc}
    197         *
    198         * @since 8.0
    199         */
    200        @Beta @Override
    201        public Builder<K, V> orderValuesBy(Comparator<? super V> valueComparator) {
    202          super.orderValuesBy(valueComparator);
    203          return this;
    204        }
    205
    206        /**
    207         * Returns a newly-created immutable list multimap.
    208         */
    209        @Override public ImmutableListMultimap<K, V> build() {
    210          return (ImmutableListMultimap<K, V>) super.build();
    211        }
    212      }
    213
    214      /**
    215       * Returns an immutable multimap containing the same mappings as {@code
    216       * multimap}. The generated multimap's key and value orderings correspond to
    217       * the iteration ordering of the {@code multimap.asMap()} view.
    218       *
    219       * <p>Despite the method name, this method attempts to avoid actually copying
    220       * the data when it is safe to do so. The exact circumstances under which a
    221       * copy will or will not be performed are undocumented and subject to change.
    222       *
    223       * @throws NullPointerException if any key or value in {@code multimap} is
    224       *         null
    225       */
    226      public static <K, V> ImmutableListMultimap<K, V> copyOf(
    227          Multimap<? extends K, ? extends V> multimap) {
    228        if (multimap.isEmpty()) {
    229          return of();
    230        }
    231
    232        // TODO(user): copy ImmutableSetMultimap by using asList() on the sets
    233        if (multimap instanceof ImmutableListMultimap) {
    234          @SuppressWarnings("unchecked") // safe since multimap is not writable
    235          ImmutableListMultimap<K, V> kvMultimap
    236              = (ImmutableListMultimap<K, V>) multimap;
    237          if (!kvMultimap.isPartialView()) {
    238            return kvMultimap;
    239          }
    240        }
    241
    242        ImmutableMap.Builder<K, ImmutableList<V>> builder = ImmutableMap.builder();
    243        int size = 0;
    244
    245        for (Map.Entry<? extends K, ? extends Collection<? extends V>> entry
    246            : multimap.asMap().entrySet()) {
    247          ImmutableList<V> list = ImmutableList.copyOf(entry.getValue());
    248          if (!list.isEmpty()) {
    249            builder.put(entry.getKey(), list);
    250            size += list.size();
    251          }
    252        }
    253
    254        return new ImmutableListMultimap<K, V>(builder.build(), size);
    255      }
    256
    257      ImmutableListMultimap(ImmutableMap<K, ImmutableList<V>> map, int size) {
    258        super(map, size);
    259      }
    260
    261      // views
    262
    263      /**
    264       * Returns an immutable list of the values for the given key.  If no mappings
    265       * in the multimap have the provided key, an empty immutable list is
    266       * returned. The values are in the same order as the parameters used to build
    267       * this multimap.
    268       */
    269      @Override public ImmutableList<V> get(@Nullable K key) {
    270        // This cast is safe as its type is known in constructor.
    271        ImmutableList<V> list = (ImmutableList<V>) map.get(key);
    272        return (list == null) ? ImmutableList.<V>of() : list;
    273      }
    274
    275      /**
    276       * Guaranteed to throw an exception and leave the multimap unmodified.
    277       *
    278       * @throws UnsupportedOperationException always
    279       */
    280      @Override public ImmutableList<V> removeAll(Object key) {
    281        throw new UnsupportedOperationException();
    282      }
    283
    284      /**
    285       * Guaranteed to throw an exception and leave the multimap unmodified.
    286       *
    287       * @throws UnsupportedOperationException always
    288       */
    289      @Override public ImmutableList<V> replaceValues(
    290          K key, Iterable<? extends V> values) {
    291        throw new UnsupportedOperationException();
    292      }
    293
    294      /**
    295       * @serialData number of distinct keys, and then for each distinct key: the
    296       *     key, the number of values for that key, and the key's values
    297       */
    298      @GwtIncompatible("java.io.ObjectOutputStream")
    299      private void writeObject(ObjectOutputStream stream) throws IOException {
    300        stream.defaultWriteObject();
    301        Serialization.writeMultimap(this, stream);
    302      }
    303
    304      @GwtIncompatible("java.io.ObjectInputStream")
    305      private void readObject(ObjectInputStream stream)
    306          throws IOException, ClassNotFoundException {
    307        stream.defaultReadObject();
    308        int keyCount = stream.readInt();
    309        if (keyCount < 0) {
    310          throw new InvalidObjectException("Invalid key count " + keyCount);
    311        }
    312        ImmutableMap.Builder<Object, ImmutableList<Object>> builder
    313            = ImmutableMap.builder();
    314        int tmpSize = 0;
    315
    316        for (int i = 0; i < keyCount; i++) {
    317          Object key = stream.readObject();
    318          int valueCount = stream.readInt();
    319          if (valueCount <= 0) {
    320            throw new InvalidObjectException("Invalid value count " + valueCount);
    321          }
    322
    323          Object[] array = new Object[valueCount];
    324          for (int j = 0; j < valueCount; j++) {
    325            array[j] = stream.readObject();
    326          }
    327          builder.put(key, ImmutableList.copyOf(array));
    328          tmpSize += valueCount;
    329        }
    330
    331        ImmutableMap<Object, ImmutableList<Object>> tmpMap;
    332        try {
    333          tmpMap = builder.build();
    334        } catch (IllegalArgumentException e) {
    335          throw (InvalidObjectException)
    336              new InvalidObjectException(e.getMessage()).initCause(e);
    337        }
    338
    339        FieldSettersHolder.MAP_FIELD_SETTER.set(this, tmpMap);
    340        FieldSettersHolder.SIZE_FIELD_SETTER.set(this, tmpSize);
    341      }
    342
    343      @GwtIncompatible("Not needed in emulated source")
    344      private static final long serialVersionUID = 0;
    345    }