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;
022import com.google.errorprone.annotations.CanIgnoreReturnValue;
023import com.google.errorprone.annotations.concurrent.LazyInit;
024import com.google.j2objc.annotations.RetainedWith;
025import java.io.IOException;
026import java.io.InvalidObjectException;
027import java.io.ObjectInputStream;
028import java.io.ObjectOutputStream;
029import java.util.Collection;
030import java.util.Comparator;
031import java.util.Map.Entry;
032import javax.annotation.Nullable;
033
034/**
035 * A {@link ListMultimap} whose contents will never change, with many other important properties
036 * detailed at {@link ImmutableCollection}.
037 *
038 * <p>See the Guava User Guide article on <a href=
039 * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained">
040 * immutable collections</a>.
041 *
042 * @author Jared Levy
043 * @since 2.0
044 */
045@GwtCompatible(serializable = true, emulated = true)
046public class ImmutableListMultimap<K, V> extends ImmutableMultimap<K, V>
047    implements ListMultimap<K, V> {
048
049  /** Returns the empty multimap. */
050  // Casting is safe because the multimap will never hold any elements.
051  @SuppressWarnings("unchecked")
052  public static <K, V> ImmutableListMultimap<K, V> of() {
053    return (ImmutableListMultimap<K, V>) EmptyImmutableListMultimap.INSTANCE;
054  }
055
056  /**
057   * Returns an immutable multimap containing a single entry.
058   */
059  public static <K, V> ImmutableListMultimap<K, V> of(K k1, V v1) {
060    ImmutableListMultimap.Builder<K, V> builder = ImmutableListMultimap.builder();
061    builder.put(k1, v1);
062    return builder.build();
063  }
064
065  /**
066   * Returns an immutable multimap containing the given entries, in order.
067   */
068  public static <K, V> ImmutableListMultimap<K, V> of(K k1, V v1, K k2, V v2) {
069    ImmutableListMultimap.Builder<K, V> builder = ImmutableListMultimap.builder();
070    builder.put(k1, v1);
071    builder.put(k2, v2);
072    return builder.build();
073  }
074
075  /**
076   * Returns an immutable multimap containing the given entries, in order.
077   */
078  public static <K, V> ImmutableListMultimap<K, V> of(K k1, V v1, K k2, V v2, K k3, V v3) {
079    ImmutableListMultimap.Builder<K, V> builder = ImmutableListMultimap.builder();
080    builder.put(k1, v1);
081    builder.put(k2, v2);
082    builder.put(k3, v3);
083    return builder.build();
084  }
085
086  /**
087   * Returns an immutable multimap containing the given entries, in order.
088   */
089  public static <K, V> ImmutableListMultimap<K, V> of(
090      K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4) {
091    ImmutableListMultimap.Builder<K, V> builder = ImmutableListMultimap.builder();
092    builder.put(k1, v1);
093    builder.put(k2, v2);
094    builder.put(k3, v3);
095    builder.put(k4, v4);
096    return builder.build();
097  }
098
099  /**
100   * Returns an immutable multimap containing the given entries, in order.
101   */
102  public static <K, V> ImmutableListMultimap<K, V> of(
103      K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5) {
104    ImmutableListMultimap.Builder<K, V> builder = ImmutableListMultimap.builder();
105    builder.put(k1, v1);
106    builder.put(k2, v2);
107    builder.put(k3, v3);
108    builder.put(k4, v4);
109    builder.put(k5, v5);
110    return builder.build();
111  }
112
113  // looking for of() with > 5 entries? Use the builder instead.
114
115  /**
116   * Returns a new builder. The generated builder is equivalent to the builder
117   * created by the {@link Builder} constructor.
118   */
119  public static <K, V> Builder<K, V> builder() {
120    return new Builder<K, V>();
121  }
122
123  /**
124   * A builder for creating immutable {@code ListMultimap} instances, especially
125   * {@code public static final} multimaps ("constant multimaps"). Example:
126   * <pre>   {@code
127   *
128   *   static final Multimap<String, Integer> STRING_TO_INTEGER_MULTIMAP =
129   *       new ImmutableListMultimap.Builder<String, Integer>()
130   *           .put("one", 1)
131   *           .putAll("several", 1, 2, 3)
132   *           .putAll("many", 1, 2, 3, 4, 5)
133   *           .build();}</pre>
134   *
135   * <p>Builder instances can be reused; it is safe to call {@link #build} multiple
136   * times to build multiple multimaps in series. Each multimap contains the
137   * key-value mappings in the previously created multimaps.
138   *
139   * @since 2.0
140   */
141  public static final class Builder<K, V> extends ImmutableMultimap.Builder<K, V> {
142    /**
143     * Creates a new builder. The returned builder is equivalent to the builder
144     * generated by {@link ImmutableListMultimap#builder}.
145     */
146    public Builder() {}
147
148    @CanIgnoreReturnValue
149    @Override
150    public Builder<K, V> put(K key, V value) {
151      super.put(key, value);
152      return this;
153    }
154
155    /**
156     * {@inheritDoc}
157     *
158     * @since 11.0
159     */
160    @CanIgnoreReturnValue
161    @Override
162    public Builder<K, V> put(Entry<? extends K, ? extends V> entry) {
163      super.put(entry);
164      return this;
165    }
166
167    /**
168     * {@inheritDoc}
169     *
170     * @since 19.0
171     */
172    @CanIgnoreReturnValue
173    @Beta
174    @Override
175    public Builder<K, V> putAll(Iterable<? extends Entry<? extends K, ? extends V>> entries) {
176      super.putAll(entries);
177      return this;
178    }
179
180    @CanIgnoreReturnValue
181    @Override
182    public Builder<K, V> putAll(K key, Iterable<? extends V> values) {
183      super.putAll(key, values);
184      return this;
185    }
186
187    @CanIgnoreReturnValue
188    @Override
189    public Builder<K, V> putAll(K key, V... values) {
190      super.putAll(key, values);
191      return this;
192    }
193
194    @CanIgnoreReturnValue
195    @Override
196    public Builder<K, V> putAll(Multimap<? extends K, ? extends V> multimap) {
197      super.putAll(multimap);
198      return this;
199    }
200
201    /**
202     * {@inheritDoc}
203     *
204     * @since 8.0
205     */
206    @CanIgnoreReturnValue
207    @Override
208    public Builder<K, V> orderKeysBy(Comparator<? super K> keyComparator) {
209      super.orderKeysBy(keyComparator);
210      return this;
211    }
212
213    /**
214     * {@inheritDoc}
215     *
216     * @since 8.0
217     */
218    @CanIgnoreReturnValue
219    @Override
220    public Builder<K, V> orderValuesBy(Comparator<? super V> valueComparator) {
221      super.orderValuesBy(valueComparator);
222      return this;
223    }
224
225    /**
226     * Returns a newly-created immutable list multimap.
227     */
228    @Override
229    public ImmutableListMultimap<K, V> build() {
230      return (ImmutableListMultimap<K, V>) super.build();
231    }
232  }
233
234  /**
235   * Returns an immutable multimap containing the same mappings as {@code
236   * multimap}. The generated multimap's key and value orderings correspond to
237   * the iteration ordering of the {@code multimap.asMap()} view.
238   *
239   * <p>Despite the method name, this method attempts to avoid actually copying
240   * the data when it is safe to do so. The exact circumstances under which a
241   * copy will or will not be performed are undocumented and subject to change.
242   *
243   * @throws NullPointerException if any key or value in {@code multimap} is
244   *         null
245   */
246  public static <K, V> ImmutableListMultimap<K, V> copyOf(
247      Multimap<? extends K, ? extends V> multimap) {
248    if (multimap.isEmpty()) {
249      return of();
250    }
251
252    // TODO(lowasser): copy ImmutableSetMultimap by using asList() on the sets
253    if (multimap instanceof ImmutableListMultimap) {
254      @SuppressWarnings("unchecked") // safe since multimap is not writable
255      ImmutableListMultimap<K, V> kvMultimap = (ImmutableListMultimap<K, V>) multimap;
256      if (!kvMultimap.isPartialView()) {
257        return kvMultimap;
258      }
259    }
260
261    ImmutableMap.Builder<K, ImmutableList<V>> builder =
262        new ImmutableMap.Builder<K, ImmutableList<V>>(multimap.asMap().size());
263    int size = 0;
264
265    for (Entry<? extends K, ? extends Collection<? extends V>> entry :
266        multimap.asMap().entrySet()) {
267      ImmutableList<V> list = ImmutableList.copyOf(entry.getValue());
268      if (!list.isEmpty()) {
269        builder.put(entry.getKey(), list);
270        size += list.size();
271      }
272    }
273
274    return new ImmutableListMultimap<K, V>(builder.build(), size);
275  }
276
277  /**
278   * Returns an immutable multimap containing the specified entries.  The
279   * returned multimap iterates over keys in the order they were first
280   * encountered in the input, and the values for each key are iterated in the
281   * order they were encountered.
282   *
283   * @throws NullPointerException if any key, value, or entry is null
284   * @since 19.0
285   */
286  @Beta
287  public static <K, V> ImmutableListMultimap<K, V> copyOf(
288      Iterable<? extends Entry<? extends K, ? extends V>> entries) {
289    return new Builder<K, V>().putAll(entries).build();
290  }
291
292  ImmutableListMultimap(ImmutableMap<K, ImmutableList<V>> map, int size) {
293    super(map, size);
294  }
295
296  // views
297
298  /**
299   * Returns an immutable list of the values for the given key.  If no mappings
300   * in the multimap have the provided key, an empty immutable list is
301   * returned. The values are in the same order as the parameters used to build
302   * this multimap.
303   */
304  @Override
305  public ImmutableList<V> get(@Nullable K key) {
306    // This cast is safe as its type is known in constructor.
307    ImmutableList<V> list = (ImmutableList<V>) map.get(key);
308    return (list == null) ? ImmutableList.<V>of() : list;
309  }
310
311  @LazyInit
312  @RetainedWith
313  private transient ImmutableListMultimap<V, K> inverse;
314
315  /**
316   * {@inheritDoc}
317   *
318   * <p>Because an inverse of a list multimap can contain multiple pairs with
319   * the same key and value, this method returns an {@code
320   * ImmutableListMultimap} rather than the {@code ImmutableMultimap} specified
321   * in the {@code ImmutableMultimap} class.
322   *
323   * @since 11.0
324   */
325  @Override
326  public ImmutableListMultimap<V, K> inverse() {
327    ImmutableListMultimap<V, K> result = inverse;
328    return (result == null) ? (inverse = invert()) : result;
329  }
330
331  private ImmutableListMultimap<V, K> invert() {
332    Builder<V, K> builder = builder();
333    for (Entry<K, V> entry : entries()) {
334      builder.put(entry.getValue(), entry.getKey());
335    }
336    ImmutableListMultimap<V, K> invertedMultimap = builder.build();
337    invertedMultimap.inverse = this;
338    return invertedMultimap;
339  }
340
341  /**
342   * Guaranteed to throw an exception and leave the multimap unmodified.
343   *
344   * @throws UnsupportedOperationException always
345   * @deprecated Unsupported operation.
346   */
347  @CanIgnoreReturnValue
348  @Deprecated
349  @Override
350  public ImmutableList<V> removeAll(Object key) {
351    throw new UnsupportedOperationException();
352  }
353
354  /**
355   * Guaranteed to throw an exception and leave the multimap unmodified.
356   *
357   * @throws UnsupportedOperationException always
358   * @deprecated Unsupported operation.
359   */
360  @CanIgnoreReturnValue
361  @Deprecated
362  @Override
363  public ImmutableList<V> replaceValues(K key, Iterable<? extends V> values) {
364    throw new UnsupportedOperationException();
365  }
366
367  /**
368   * @serialData number of distinct keys, and then for each distinct key: the
369   *     key, the number of values for that key, and the key's values
370   */
371  @GwtIncompatible // java.io.ObjectOutputStream
372  private void writeObject(ObjectOutputStream stream) throws IOException {
373    stream.defaultWriteObject();
374    Serialization.writeMultimap(this, stream);
375  }
376
377  @GwtIncompatible // java.io.ObjectInputStream
378  private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException {
379    stream.defaultReadObject();
380    int keyCount = stream.readInt();
381    if (keyCount < 0) {
382      throw new InvalidObjectException("Invalid key count " + keyCount);
383    }
384    ImmutableMap.Builder<Object, ImmutableList<Object>> builder = ImmutableMap.builder();
385    int tmpSize = 0;
386
387    for (int i = 0; i < keyCount; i++) {
388      Object key = stream.readObject();
389      int valueCount = stream.readInt();
390      if (valueCount <= 0) {
391        throw new InvalidObjectException("Invalid value count " + valueCount);
392      }
393
394      ImmutableList.Builder<Object> valuesBuilder = ImmutableList.builder();
395      for (int j = 0; j < valueCount; j++) {
396        valuesBuilder.add(stream.readObject());
397      }
398      builder.put(key, valuesBuilder.build());
399      tmpSize += valueCount;
400    }
401
402    ImmutableMap<Object, ImmutableList<Object>> tmpMap;
403    try {
404      tmpMap = builder.build();
405    } catch (IllegalArgumentException e) {
406      throw (InvalidObjectException) new InvalidObjectException(e.getMessage()).initCause(e);
407    }
408
409    FieldSettersHolder.MAP_FIELD_SETTER.set(this, tmpMap);
410    FieldSettersHolder.SIZE_FIELD_SETTER.set(this, tmpSize);
411  }
412
413  @GwtIncompatible // Not needed in emulated source
414  private static final long serialVersionUID = 0;
415}