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 import com.google.common.base.Function;
025
026 import java.io.IOException;
027 import java.io.InvalidObjectException;
028 import java.io.ObjectInputStream;
029 import java.io.ObjectOutputStream;
030 import java.util.Arrays;
031 import java.util.Collection;
032 import java.util.Collections;
033 import java.util.Comparator;
034 import java.util.LinkedHashMap;
035 import java.util.List;
036 import java.util.Map;
037 import java.util.Map.Entry;
038 import java.util.TreeMap;
039
040 import javax.annotation.Nullable;
041
042 /**
043 * An immutable {@link SetMultimap} with reliable user-specified key and value
044 * iteration order. Does not permit null keys or values.
045 *
046 * <p>Unlike {@link Multimaps#unmodifiableSetMultimap(SetMultimap)}, which is
047 * a <i>view</i> of a separate multimap which can still change, an instance of
048 * {@code ImmutableSetMultimap} contains its own data and will <i>never</i>
049 * change. {@code ImmutableSetMultimap} is convenient for
050 * {@code public static final} multimaps ("constant multimaps") and also lets
051 * you easily make a "defensive copy" of a multimap provided to your class by
052 * a caller.
053 *
054 * <p><b>Note:</b> Although this class is not final, it cannot be subclassed as
055 * it has no public or protected constructors. Thus, instances of this class
056 * are guaranteed to be immutable.
057 *
058 * <p>See the Guava User Guide article on <a href=
059 * "http://code.google.com/p/guava-libraries/wiki/ImmutableCollectionsExplained">
060 * immutable collections</a>.
061 *
062 * @author Mike Ward
063 * @since 2.0 (imported from Google Collections Library)
064 */
065 @GwtCompatible(serializable = true, emulated = true)
066 public class ImmutableSetMultimap<K, V>
067 extends ImmutableMultimap<K, V>
068 implements SetMultimap<K, V> {
069
070 /** Returns the empty multimap. */
071 // Casting is safe because the multimap will never hold any elements.
072 @SuppressWarnings("unchecked")
073 public static <K, V> ImmutableSetMultimap<K, V> of() {
074 return (ImmutableSetMultimap<K, V>) EmptyImmutableSetMultimap.INSTANCE;
075 }
076
077 /**
078 * Returns an immutable multimap containing a single entry.
079 */
080 public static <K, V> ImmutableSetMultimap<K, V> of(K k1, V v1) {
081 ImmutableSetMultimap.Builder<K, V> builder = ImmutableSetMultimap.builder();
082 builder.put(k1, v1);
083 return builder.build();
084 }
085
086 /**
087 * Returns an immutable multimap containing the given entries, in order.
088 * Repeated occurrences of an entry (according to {@link Object#equals}) after
089 * the first are ignored.
090 */
091 public static <K, V> ImmutableSetMultimap<K, V> of(K k1, V v1, K k2, V v2) {
092 ImmutableSetMultimap.Builder<K, V> builder = ImmutableSetMultimap.builder();
093 builder.put(k1, v1);
094 builder.put(k2, v2);
095 return builder.build();
096 }
097
098 /**
099 * Returns an immutable multimap containing the given entries, in order.
100 * Repeated occurrences of an entry (according to {@link Object#equals}) after
101 * the first are ignored.
102 */
103 public static <K, V> ImmutableSetMultimap<K, V> of(
104 K k1, V v1, K k2, V v2, K k3, V v3) {
105 ImmutableSetMultimap.Builder<K, V> builder = ImmutableSetMultimap.builder();
106 builder.put(k1, v1);
107 builder.put(k2, v2);
108 builder.put(k3, v3);
109 return builder.build();
110 }
111
112 /**
113 * Returns an immutable multimap containing the given entries, in order.
114 * Repeated occurrences of an entry (according to {@link Object#equals}) after
115 * the first are ignored.
116 */
117 public static <K, V> ImmutableSetMultimap<K, V> of(
118 K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4) {
119 ImmutableSetMultimap.Builder<K, V> builder = ImmutableSetMultimap.builder();
120 builder.put(k1, v1);
121 builder.put(k2, v2);
122 builder.put(k3, v3);
123 builder.put(k4, v4);
124 return builder.build();
125 }
126
127 /**
128 * Returns an immutable multimap containing the given entries, in order.
129 * Repeated occurrences of an entry (according to {@link Object#equals}) after
130 * the first are ignored.
131 */
132 public static <K, V> ImmutableSetMultimap<K, V> of(
133 K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5) {
134 ImmutableSetMultimap.Builder<K, V> builder = ImmutableSetMultimap.builder();
135 builder.put(k1, v1);
136 builder.put(k2, v2);
137 builder.put(k3, v3);
138 builder.put(k4, v4);
139 builder.put(k5, v5);
140 return builder.build();
141 }
142
143 // looking for of() with > 5 entries? Use the builder instead.
144
145 /**
146 * Returns a new {@link Builder}.
147 */
148 public static <K, V> Builder<K, V> builder() {
149 return new Builder<K, V>();
150 }
151
152 /**
153 * Multimap for {@link ImmutableSetMultimap.Builder} that maintains key
154 * and value orderings and performs better than {@link LinkedHashMultimap}.
155 */
156 private static class BuilderMultimap<K, V> extends AbstractMultimap<K, V> {
157 BuilderMultimap() {
158 super(new LinkedHashMap<K, Collection<V>>());
159 }
160
161 @Override
162 Collection<V> createCollection() {
163 return Sets.newLinkedHashSet();
164 }
165 private static final long serialVersionUID = 0;
166 }
167
168 /**
169 * Multimap for {@link ImmutableSetMultimap.Builder} that sorts keys and
170 * maintains value orderings.
171 */
172 private static class SortedKeyBuilderMultimap<K, V>
173 extends AbstractMultimap<K, V> {
174 SortedKeyBuilderMultimap(
175 Comparator<? super K> keyComparator, Multimap<K, V> multimap) {
176 super(new TreeMap<K, Collection<V>>(keyComparator));
177 putAll(multimap);
178 }
179
180 @Override
181 Collection<V> createCollection() {
182 return Sets.newLinkedHashSet();
183 }
184 private static final long serialVersionUID = 0;
185 }
186
187 /**
188 * A builder for creating immutable {@code SetMultimap} instances, especially
189 * {@code public static final} multimaps ("constant multimaps"). Example:
190 * <pre> {@code
191 *
192 * static final Multimap<String, Integer> STRING_TO_INTEGER_MULTIMAP =
193 * new ImmutableSetMultimap.Builder<String, Integer>()
194 * .put("one", 1)
195 * .putAll("several", 1, 2, 3)
196 * .putAll("many", 1, 2, 3, 4, 5)
197 * .build();}</pre>
198 *
199 * Builder instances can be reused; it is safe to call {@link #build} multiple
200 * times to build multiple multimaps in series. Each multimap contains the
201 * key-value mappings in the previously created multimaps.
202 *
203 * @since 2.0 (imported from Google Collections Library)
204 */
205 public static final class Builder<K, V>
206 extends ImmutableMultimap.Builder<K, V> {
207 /**
208 * Creates a new builder. The returned builder is equivalent to the builder
209 * generated by {@link ImmutableSetMultimap#builder}.
210 */
211 public Builder() {
212 builderMultimap = new BuilderMultimap<K, V>();
213 }
214
215 /**
216 * Adds a key-value mapping to the built multimap if it is not already
217 * present.
218 */
219
220 @Override
221 public Builder<K, V> put(K key, V value) {
222 builderMultimap.put(checkNotNull(key), checkNotNull(value));
223 return this;
224 }
225
226 /**
227 * Adds an entry to the built multimap if it is not already present.
228 *
229 * @since 11.0
230 */
231
232 @Override
233 public Builder<K, V> put(Entry<? extends K, ? extends V> entry) {
234 builderMultimap.put(
235 checkNotNull(entry.getKey()), checkNotNull(entry.getValue()));
236 return this;
237 }
238
239
240 @Override
241 public Builder<K, V> putAll(K key, Iterable<? extends V> values) {
242 Collection<V> collection = builderMultimap.get(checkNotNull(key));
243 for (V value : values) {
244 collection.add(checkNotNull(value));
245 }
246 return this;
247 }
248
249
250 @Override
251 public Builder<K, V> putAll(K key, V... values) {
252 return putAll(key, Arrays.asList(values));
253 }
254
255
256 @Override
257 public Builder<K, V> putAll(
258 Multimap<? extends K, ? extends V> multimap) {
259 for (Entry<? extends K, ? extends Collection<? extends V>> entry
260 : multimap.asMap().entrySet()) {
261 putAll(entry.getKey(), entry.getValue());
262 }
263 return this;
264 }
265
266 /**
267 * {@inheritDoc}
268 *
269 * @since 8.0
270 */
271 @Beta @Override
272 public Builder<K, V> orderKeysBy(Comparator<? super K> keyComparator) {
273 this.keyComparator = checkNotNull(keyComparator);
274 return this;
275 }
276
277 /**
278 * Specifies the ordering of the generated multimap's values for each key.
279 *
280 * <p>If this method is called, the sets returned by the {@code get()}
281 * method of the generated multimap and its {@link Multimap#asMap()} view
282 * are {@link ImmutableSortedSet} instances. However, serialization does not
283 * preserve that property, though it does maintain the key and value
284 * ordering.
285 *
286 * @since 8.0
287 */
288 // TODO: Make serialization behavior consistent.
289 @Beta @Override
290 public Builder<K, V> orderValuesBy(Comparator<? super V> valueComparator) {
291 super.orderValuesBy(valueComparator);
292 return this;
293 }
294
295 /**
296 * Returns a newly-created immutable set multimap.
297 */
298
299 @Override
300 public ImmutableSetMultimap<K, V> build() {
301 if (keyComparator != null) {
302 Multimap<K, V> sortedCopy = new BuilderMultimap<K, V>();
303 List<Map.Entry<K, Collection<V>>> entries = Lists.newArrayList(
304 builderMultimap.asMap().entrySet());
305 Collections.sort(
306 entries,
307 Ordering.from(keyComparator).onResultOf(new Function<Entry<K, Collection<V>>, K>() {
308 public K apply(Entry<K, Collection<V>> entry) {
309 return entry.getKey();
310 }
311 }));
312 for (Map.Entry<K, Collection<V>> entry : entries) {
313 sortedCopy.putAll(entry.getKey(), entry.getValue());
314 }
315 builderMultimap = sortedCopy;
316 }
317 return copyOf(builderMultimap, valueComparator);
318 }
319 }
320
321 /**
322 * Returns an immutable set multimap containing the same mappings as
323 * {@code multimap}. The generated multimap's key and value orderings
324 * correspond to the iteration ordering of the {@code multimap.asMap()} view.
325 * Repeated occurrences of an entry in the multimap after the first are
326 * ignored.
327 *
328 * <p>Despite the method name, this method attempts to avoid actually copying
329 * the data when it is safe to do so. The exact circumstances under which a
330 * copy will or will not be performed are undocumented and subject to change.
331 *
332 * @throws NullPointerException if any key or value in {@code multimap} is
333 * null
334 */
335 public static <K, V> ImmutableSetMultimap<K, V> copyOf(
336 Multimap<? extends K, ? extends V> multimap) {
337 return copyOf(multimap, null);
338 }
339
340 private static <K, V> ImmutableSetMultimap<K, V> copyOf(
341 Multimap<? extends K, ? extends V> multimap,
342 Comparator<? super V> valueComparator) {
343 checkNotNull(multimap); // eager for GWT
344 if (multimap.isEmpty() && valueComparator == null) {
345 return of();
346 }
347
348 if (multimap instanceof ImmutableSetMultimap) {
349 @SuppressWarnings("unchecked") // safe since multimap is not writable
350 ImmutableSetMultimap<K, V> kvMultimap
351 = (ImmutableSetMultimap<K, V>) multimap;
352 if (!kvMultimap.isPartialView()) {
353 return kvMultimap;
354 }
355 }
356
357 ImmutableMap.Builder<K, ImmutableSet<V>> builder = ImmutableMap.builder();
358 int size = 0;
359
360 for (Entry<? extends K, ? extends Collection<? extends V>> entry
361 : multimap.asMap().entrySet()) {
362 K key = entry.getKey();
363 Collection<? extends V> values = entry.getValue();
364 ImmutableSet<V> set = (valueComparator == null)
365 ? ImmutableSet.copyOf(values)
366 : ImmutableSortedSet.copyOf(valueComparator, values);
367 if (!set.isEmpty()) {
368 builder.put(key, set);
369 size += set.size();
370 }
371 }
372
373 return new ImmutableSetMultimap<K, V>(
374 builder.build(), size, valueComparator);
375 }
376
377 // Returned by get() when values are sorted and a missing key is provided.
378 private final transient ImmutableSortedSet<V> emptySet;
379
380 ImmutableSetMultimap(ImmutableMap<K, ImmutableSet<V>> map, int size,
381 @Nullable Comparator<? super V> valueComparator) {
382 super(map, size);
383 this.emptySet = (valueComparator == null)
384 ? null : ImmutableSortedSet.<V>emptySet(valueComparator);
385 }
386
387 // views
388
389 /**
390 * Returns an immutable set of the values for the given key. If no mappings
391 * in the multimap have the provided key, an empty immutable set is returned.
392 * The values are in the same order as the parameters used to build this
393 * multimap.
394 */
395
396 @Override
397 public ImmutableSet<V> get(@Nullable K key) {
398 // This cast is safe as its type is known in constructor.
399 ImmutableSet<V> set = (ImmutableSet<V>) map.get(key);
400 if (set != null) {
401 return set;
402 } else if (emptySet != null) {
403 return emptySet;
404 } else {
405 return ImmutableSet.<V>of();
406 }
407 }
408
409 private transient ImmutableSetMultimap<V, K> inverse;
410
411 /**
412 * {@inheritDoc}
413 *
414 * <p>Because an inverse of a set multimap cannot contain multiple pairs with
415 * the same key and value, this method returns an {@code ImmutableSetMultimap}
416 * rather than the {@code ImmutableMultimap} specified in the {@code
417 * ImmutableMultimap} class.
418 *
419 * @since 11.0
420 */
421
422 @Override
423 @Beta
424 public ImmutableSetMultimap<V, K> inverse() {
425 ImmutableSetMultimap<V, K> result = inverse;
426 return (result == null) ? (inverse = invert()) : result;
427 }
428
429 private ImmutableSetMultimap<V, K> invert() {
430 Builder<V, K> builder = builder();
431 for (Entry<K, V> entry : entries()) {
432 builder.put(entry.getValue(), entry.getKey());
433 }
434 ImmutableSetMultimap<V, K> invertedMultimap = builder.build();
435 invertedMultimap.inverse = this;
436 return invertedMultimap;
437 }
438
439 /**
440 * Guaranteed to throw an exception and leave the multimap unmodified.
441 *
442 * @throws UnsupportedOperationException always
443 */
444
445 @Override
446 public ImmutableSet<V> removeAll(Object key) {
447 throw new UnsupportedOperationException();
448 }
449
450 /**
451 * Guaranteed to throw an exception and leave the multimap unmodified.
452 *
453 * @throws UnsupportedOperationException always
454 */
455
456 @Override
457 public ImmutableSet<V> replaceValues(
458 K key, Iterable<? extends V> values) {
459 throw new UnsupportedOperationException();
460 }
461
462 private transient ImmutableSet<Entry<K, V>> entries;
463
464 /**
465 * Returns an immutable collection of all key-value pairs in the multimap.
466 * Its iterator traverses the values for the first key, the values for the
467 * second key, and so on.
468 */
469 // TODO(kevinb): Fix this so that two copies of the entries are not created.
470
471 @Override
472 public ImmutableSet<Entry<K, V>> entries() {
473 ImmutableSet<Entry<K, V>> result = entries;
474 return (result == null)
475 ? (entries = ImmutableSet.copyOf(super.entries()))
476 : result;
477 }
478
479 /**
480 * @serialData number of distinct keys, and then for each distinct key: the
481 * key, the number of values for that key, and the key's values
482 */
483 @GwtIncompatible("java.io.ObjectOutputStream")
484 private void writeObject(ObjectOutputStream stream) throws IOException {
485 stream.defaultWriteObject();
486 Serialization.writeMultimap(this, stream);
487 }
488
489 @GwtIncompatible("java.io.ObjectInputStream")
490 private void readObject(ObjectInputStream stream)
491 throws IOException, ClassNotFoundException {
492 stream.defaultReadObject();
493 int keyCount = stream.readInt();
494 if (keyCount < 0) {
495 throw new InvalidObjectException("Invalid key count " + keyCount);
496 }
497 ImmutableMap.Builder<Object, ImmutableSet<Object>> builder
498 = ImmutableMap.builder();
499 int tmpSize = 0;
500
501 for (int i = 0; i < keyCount; i++) {
502 Object key = stream.readObject();
503 int valueCount = stream.readInt();
504 if (valueCount <= 0) {
505 throw new InvalidObjectException("Invalid value count " + valueCount);
506 }
507
508 Object[] array = new Object[valueCount];
509 for (int j = 0; j < valueCount; j++) {
510 array[j] = stream.readObject();
511 }
512 ImmutableSet<Object> valueSet = ImmutableSet.copyOf(array);
513 if (valueSet.size() != array.length) {
514 throw new InvalidObjectException(
515 "Duplicate key-value pairs exist for key " + key);
516 }
517 builder.put(key, valueSet);
518 tmpSize += valueCount;
519 }
520
521 ImmutableMap<Object, ImmutableSet<Object>> tmpMap;
522 try {
523 tmpMap = builder.build();
524 } catch (IllegalArgumentException e) {
525 throw (InvalidObjectException)
526 new InvalidObjectException(e.getMessage()).initCause(e);
527 }
528
529 FieldSettersHolder.MAP_FIELD_SETTER.set(this, tmpMap);
530 FieldSettersHolder.SIZE_FIELD_SETTER.set(this, tmpSize);
531 }
532
533 @GwtIncompatible("not needed in emulated source.")
534 private static final long serialVersionUID = 0;
535 }