    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.Entry;
    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     * <p>See the Guava User Guide article on <a href=
    050     * "http://code.google.com/p/guava-libraries/wiki/ImmutableCollectionsExplained">
    051     * immutable collections</a>.
    052     *
    053     * @author Jared Levy
    054     * @since 2.0 (imported from Google Collections Library)
    055     */
    056    @GwtCompatible(serializable = true, emulated = true)
    057    public class ImmutableListMultimap<K, V>
    058        extends ImmutableMultimap<K, V>
    059        implements ListMultimap<K, V> {
    060
    061      /** Returns the empty multimap. */
    062      // Casting is safe because the multimap will never hold any elements.
    063      @SuppressWarnings("unchecked")
    064      public static <K, V> ImmutableListMultimap<K, V> of() {
    065        return (ImmutableListMultimap<K, V>) EmptyImmutableListMultimap.INSTANCE;
    066      }
    067
    068      /**
    069       * Returns an immutable multimap containing a single entry.
    070       */
    071      public static <K, V> ImmutableListMultimap<K, V> of(K k1, V v1) {
    072        ImmutableListMultimap.Builder<K, V> builder
    073            = ImmutableListMultimap.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       */
    081      public static <K, V> ImmutableListMultimap<K, V> of(K k1, V v1, K k2, V v2) {
    082        ImmutableListMultimap.Builder<K, V> builder
    083            = ImmutableListMultimap.builder();
    084        builder.put(k1, v1);
    085        builder.put(k2, v2);
    086        return builder.build();
    087      }
    088
    089      /**
    090       * Returns an immutable multimap containing the given entries, in order.
    091       */
    092      public static <K, V> ImmutableListMultimap<K, V> of(
    093          K k1, V v1, K k2, V v2, K k3, V v3) {
    094        ImmutableListMultimap.Builder<K, V> builder
    095            = ImmutableListMultimap.builder();
    096        builder.put(k1, v1);
    097        builder.put(k2, v2);
    098        builder.put(k3, v3);
    099        return builder.build();
    100      }
    101
    102      /**
    103       * Returns an immutable multimap containing the given entries, in order.
    104       */
    105      public static <K, V> ImmutableListMultimap<K, V> of(
    106          K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4) {
    107        ImmutableListMultimap.Builder<K, V> builder
    108            = ImmutableListMultimap.builder();
    109        builder.put(k1, v1);
    110        builder.put(k2, v2);
    111        builder.put(k3, v3);
    112        builder.put(k4, v4);
    113        return builder.build();
    114      }
    115
    116      /**
    117       * Returns an immutable multimap containing the given entries, in order.
    118       */
    119      public static <K, V> ImmutableListMultimap<K, V> of(
    120          K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5) {
    121        ImmutableListMultimap.Builder<K, V> builder
    122            = ImmutableListMultimap.builder();
    123        builder.put(k1, v1);
    124        builder.put(k2, v2);
    125        builder.put(k3, v3);
    126        builder.put(k4, v4);
    127        builder.put(k5, v5);
    128        return builder.build();
    129      }
    130
    131      // looking for of() with > 5 entries? Use the builder instead.
    132
    133      /**
    134       * Returns a new builder. The generated builder is equivalent to the builder
    135       * created by the {@link Builder} constructor.
    136       */
    137      public static <K, V> Builder<K, V> builder() {
    138        return new Builder<K, V>();
    139      }
    140
    141      /**
    142       * A builder for creating immutable {@code ListMultimap} instances, especially
    143       * {@code public static final} multimaps ("constant multimaps"). Example:
    144       * <pre>   {@code
    145       *
    146       *   static final Multimap<String, Integer> STRING_TO_INTEGER_MULTIMAP =
    147       *       new ImmutableListMultimap.Builder<String, Integer>()
    148       *           .put("one", 1)
    149       *           .putAll("several", 1, 2, 3)
    150       *           .putAll("many", 1, 2, 3, 4, 5)
    151       *           .build();}</pre>
    152       *
    153       * Builder instances can be reused; it is safe to call {@link #build} multiple
    154       * times to build multiple multimaps in series. Each multimap contains the
    155       * key-value mappings in the previously created multimaps.
    156       *
    157       * @since 2.0 (imported from Google Collections Library)
    158       */
    159      public static final class Builder<K, V>
    160          extends ImmutableMultimap.Builder<K, V> {
    161        /**
    162         * Creates a new builder. The returned builder is equivalent to the builder
    163         * generated by {@link ImmutableListMultimap#builder}.
    164         */
    165        public Builder() {}
    166
    167        @Override public Builder<K, V> put(K key, V value) {
    168          super.put(key, value);
    169          return this;
    170        }
    171
    172        /**
    173         * {@inheritDoc}
    174         *
    175         * @since 11.0
    176         */
    177        @Override public Builder<K, V> put(
    178            Entry<? extends K, ? extends V> entry) {
    179          super.put(entry);
    180          return this;
    181        }
    182
    183        @Override public Builder<K, V> putAll(K key, Iterable<? extends V> values) {
    184          super.putAll(key, values);
    185          return this;
    186        }
    187
    188        @Override public Builder<K, V> putAll(K key, V... values) {
    189          super.putAll(key, values);
    190          return this;
    191        }
    192
    193        @Override public Builder<K, V> putAll(
    194            Multimap<? extends K, ? extends V> multimap) {
    195          super.putAll(multimap);
    196          return this;
    197        }
    198
    199        /**
    200         * {@inheritDoc}
    201         *
    202         * @since 8.0
    203         */
    204        @Beta @Override
    205        public Builder<K, V> orderKeysBy(Comparator<? super K> keyComparator) {
    206          super.orderKeysBy(keyComparator);
    207          return this;
    208        }
    209
    210        /**
    211         * {@inheritDoc}
    212         *
    213         * @since 8.0
    214         */
    215        @Beta @Override
    216        public Builder<K, V> orderValuesBy(Comparator<? super V> valueComparator) {
    217          super.orderValuesBy(valueComparator);
    218          return this;
    219        }
    220
    221        /**
    222         * Returns a newly-created immutable list multimap.
    223         */
    224        @Override public ImmutableListMultimap<K, V> build() {
    225          return (ImmutableListMultimap<K, V>) super.build();
    226        }
    227      }
    228
    229      /**
    230       * Returns an immutable multimap containing the same mappings as {@code
    231       * multimap}. The generated multimap's key and value orderings correspond to
    232       * the iteration ordering of the {@code multimap.asMap()} view.
    233       *
    234       * <p>Despite the method name, this method attempts to avoid actually copying
    235       * the data when it is safe to do so. The exact circumstances under which a
    236       * copy will or will not be performed are undocumented and subject to change.
    237       *
    238       * @throws NullPointerException if any key or value in {@code multimap} is
    239       *         null
    240       */
    241      public static <K, V> ImmutableListMultimap<K, V> copyOf(
    242          Multimap<? extends K, ? extends V> multimap) {
    243        if (multimap.isEmpty()) {
    244          return of();
    245        }
    246
    247        // TODO(user): copy ImmutableSetMultimap by using asList() on the sets
    248        if (multimap instanceof ImmutableListMultimap) {
    249          @SuppressWarnings("unchecked") // safe since multimap is not writable
    250          ImmutableListMultimap<K, V> kvMultimap
    251              = (ImmutableListMultimap<K, V>) multimap;
    252          if (!kvMultimap.isPartialView()) {
    253            return kvMultimap;
    254          }
    255        }
    256
    257        ImmutableMap.Builder<K, ImmutableList<V>> builder = ImmutableMap.builder();
    258        int size = 0;
    259
    260        for (Entry<? extends K, ? extends Collection<? extends V>> entry
    261            : multimap.asMap().entrySet()) {
    262          ImmutableList<V> list = ImmutableList.copyOf(entry.getValue());
    263          if (!list.isEmpty()) {
    264            builder.put(entry.getKey(), list);
    265            size += list.size();
    266          }
    267        }
    268
    269        return new ImmutableListMultimap<K, V>(builder.build(), size);
    270      }
    271
    272      ImmutableListMultimap(ImmutableMap<K, ImmutableList<V>> map, int size) {
    273        super(map, size);
    274      }
    275
    276      // views
    277
    278      /**
    279       * Returns an immutable list of the values for the given key.  If no mappings
    280       * in the multimap have the provided key, an empty immutable list is
    281       * returned. The values are in the same order as the parameters used to build
    282       * this multimap.
    283       */
    284      @Override public ImmutableList<V> get(@Nullable K key) {
    285        // This cast is safe as its type is known in constructor.
    286        ImmutableList<V> list = (ImmutableList<V>) map.get(key);
    287        return (list == null) ? ImmutableList.<V>of() : list;
    288      }
    289
    290      private transient ImmutableListMultimap<V, K> inverse;
    291
    292      /**
    293       * {@inheritDoc}
    294       *
    295       * <p>Because an inverse of a list multimap can contain multiple pairs with
    296       * the same key and value, this method returns an {@code
    297       * ImmutableListMultimap} rather than the {@code ImmutableMultimap} specified
    298       * in the {@code ImmutableMultimap} class.
    299       *
    300       * @since 11
    301       */
    302      @Beta
    303      public ImmutableListMultimap<V, K> inverse() {
    304        ImmutableListMultimap<V, K> result = inverse;
    305        return (result == null) ? (inverse = invert()) : result;
    306      }
    307
    308      private ImmutableListMultimap<V, K> invert() {
    309        Builder<V, K> builder = builder();
    310        for (Entry<K, V> entry : entries()) {
    311          builder.put(entry.getValue(), entry.getKey());
    312        }
    313        ImmutableListMultimap<V, K> invertedMultimap = builder.build();
    314        invertedMultimap.inverse = this;
    315        return invertedMultimap;
    316      }
    317
    318      /**
    319       * Guaranteed to throw an exception and leave the multimap unmodified.
    320       *
    321       * @throws UnsupportedOperationException always
    322       */
    323      @Override public ImmutableList<V> removeAll(Object key) {
    324        throw new UnsupportedOperationException();
    325      }
    326
    327      /**
    328       * Guaranteed to throw an exception and leave the multimap unmodified.
    329       *
    330       * @throws UnsupportedOperationException always
    331       */
    332      @Override public ImmutableList<V> replaceValues(
    333          K key, Iterable<? extends V> values) {
    334        throw new UnsupportedOperationException();
    335      }
    336
    337      /**
    338       * @serialData number of distinct keys, and then for each distinct key: the
    339       *     key, the number of values for that key, and the key's values
    340       */
    341      @GwtIncompatible("java.io.ObjectOutputStream")
    342      private void writeObject(ObjectOutputStream stream) throws IOException {
    343        stream.defaultWriteObject();
    344        Serialization.writeMultimap(this, stream);
    345      }
    346
    347      @GwtIncompatible("java.io.ObjectInputStream")
    348      private void readObject(ObjectInputStream stream)
    349          throws IOException, ClassNotFoundException {
    350        stream.defaultReadObject();
    351        int keyCount = stream.readInt();
    352        if (keyCount < 0) {
    353          throw new InvalidObjectException("Invalid key count " + keyCount);
    354        }
    355        ImmutableMap.Builder<Object, ImmutableList<Object>> builder
    356            = ImmutableMap.builder();
    357        int tmpSize = 0;
    358
    359        for (int i = 0; i < keyCount; i++) {
    360          Object key = stream.readObject();
    361          int valueCount = stream.readInt();
    362          if (valueCount <= 0) {
    363            throw new InvalidObjectException("Invalid value count " + valueCount);
    364          }
    365
    366          Object[] array = new Object[valueCount];
    367          for (int j = 0; j < valueCount; j++) {
    368            array[j] = stream.readObject();
    369          }
    370          builder.put(key, ImmutableList.copyOf(array));
    371          tmpSize += valueCount;
    372        }
    373
    374        ImmutableMap<Object, ImmutableList<Object>> tmpMap;
    375        try {
    376          tmpMap = builder.build();
    377        } catch (IllegalArgumentException e) {
    378          throw (InvalidObjectException)
    379              new InvalidObjectException(e.getMessage()).initCause(e);
    380        }
    381
    382        FieldSettersHolder.MAP_FIELD_SETTER.set(this, tmpMap);
    383        FieldSettersHolder.SIZE_FIELD_SETTER.set(this, tmpSize);
    384      }
    385
    386      @GwtIncompatible("Not needed in emulated source")
    387      private static final long serialVersionUID = 0;
    388    }