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
017package com.google.common.collect;
018
019import com.google.common.annotations.Beta;
020import com.google.common.annotations.GwtCompatible;
021import com.google.common.annotations.GwtIncompatible;
022
023import java.io.IOException;
024import java.io.InvalidObjectException;
025import java.io.ObjectInputStream;
026import java.io.ObjectOutputStream;
027import java.util.Collection;
028import java.util.Comparator;
029import java.util.Map;
030
031import 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 (imported from Google Collections Library)
051 */
052@GwtCompatible(serializable = true, emulated = true)
053public 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 (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
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
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}