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 @Override Collection<V> createCollection() {
161 return Sets.newLinkedHashSet();
162 }
163 private static final long serialVersionUID = 0;
164 }
165
166 /**
167 * Multimap for {@link ImmutableSetMultimap.Builder} that sorts keys and
168 * maintains value orderings.
169 */
170 private static class SortedKeyBuilderMultimap<K, V>
171 extends AbstractMultimap<K, V> {
172 SortedKeyBuilderMultimap(
173 Comparator<? super K> keyComparator, Multimap<K, V> multimap) {
174 super(new TreeMap<K, Collection<V>>(keyComparator));
175 putAll(multimap);
176 }
177 @Override Collection<V> createCollection() {
178 return Sets.newLinkedHashSet();
179 }
180 private static final long serialVersionUID = 0;
181 }
182
183 /**
184 * A builder for creating immutable {@code SetMultimap} instances, especially
185 * {@code public static final} multimaps ("constant multimaps"). Example:
186 * <pre> {@code
187 *
188 * static final Multimap<String, Integer> STRING_TO_INTEGER_MULTIMAP =
189 * new ImmutableSetMultimap.Builder<String, Integer>()
190 * .put("one", 1)
191 * .putAll("several", 1, 2, 3)
192 * .putAll("many", 1, 2, 3, 4, 5)
193 * .build();}</pre>
194 *
195 * Builder instances can be reused; it is safe to call {@link #build} multiple
196 * times to build multiple multimaps in series. Each multimap contains the
197 * key-value mappings in the previously created multimaps.
198 *
199 * @since 2.0 (imported from Google Collections Library)
200 */
201 public static final class Builder<K, V>
202 extends ImmutableMultimap.Builder<K, V> {
203 /**
204 * Creates a new builder. The returned builder is equivalent to the builder
205 * generated by {@link ImmutableSetMultimap#builder}.
206 */
207 public Builder() {
208 builderMultimap = new BuilderMultimap<K, V>();
209 }
210
211 /**
212 * Adds a key-value mapping to the built multimap if it is not already
213 * present.
214 */
215 @Override public Builder<K, V> put(K key, V value) {
216 builderMultimap.put(checkNotNull(key), checkNotNull(value));
217 return this;
218 }
219
220 /**
221 * Adds an entry to the built multimap if it is not already present.
222 *
223 * @since 11.0
224 */
225 @Override public Builder<K, V> put(Entry<? extends K, ? extends V> entry) {
226 builderMultimap.put(
227 checkNotNull(entry.getKey()), checkNotNull(entry.getValue()));
228 return this;
229 }
230
231 @Override public Builder<K, V> putAll(K key, Iterable<? extends V> values) {
232 Collection<V> collection = builderMultimap.get(checkNotNull(key));
233 for (V value : values) {
234 collection.add(checkNotNull(value));
235 }
236 return this;
237 }
238
239 @Override public Builder<K, V> putAll(K key, V... values) {
240 return putAll(key, Arrays.asList(values));
241 }
242
243 @Override public Builder<K, V> putAll(
244 Multimap<? extends K, ? extends V> multimap) {
245 for (Entry<? extends K, ? extends Collection<? extends V>> entry
246 : multimap.asMap().entrySet()) {
247 putAll(entry.getKey(), entry.getValue());
248 }
249 return this;
250 }
251
252 /**
253 * {@inheritDoc}
254 *
255 * @since 8.0
256 */
257 @Beta @Override
258 public Builder<K, V> orderKeysBy(Comparator<? super K> keyComparator) {
259 this.keyComparator = checkNotNull(keyComparator);
260 return this;
261 }
262
263 /**
264 * Specifies the ordering of the generated multimap's values for each key.
265 *
266 * <p>If this method is called, the sets returned by the {@code get()}
267 * method of the generated multimap and its {@link Multimap#asMap()} view
268 * are {@link ImmutableSortedSet} instances. However, serialization does not
269 * preserve that property, though it does maintain the key and value
270 * ordering.
271 *
272 * @since 8.0
273 */
274 // TODO: Make serialization behavior consistent.
275 @Beta @Override
276 public Builder<K, V> orderValuesBy(Comparator<? super V> valueComparator) {
277 super.orderValuesBy(valueComparator);
278 return this;
279 }
280
281 /**
282 * Returns a newly-created immutable set multimap.
283 */
284 @Override public ImmutableSetMultimap<K, V> build() {
285 if (keyComparator != null) {
286 Multimap<K, V> sortedCopy = new BuilderMultimap<K, V>();
287 List<Map.Entry<K, Collection<V>>> entries = Lists.newArrayList(
288 builderMultimap.asMap().entrySet());
289 Collections.sort(
290 entries,
291 Ordering.from(keyComparator).onResultOf(new Function<Entry<K, Collection<V>>, K>() {
292 @Override
293 public K apply(Entry<K, Collection<V>> entry) {
294 return entry.getKey();
295 }
296 }));
297 for (Map.Entry<K, Collection<V>> entry : entries) {
298 sortedCopy.putAll(entry.getKey(), entry.getValue());
299 }
300 builderMultimap = sortedCopy;
301 }
302 return copyOf(builderMultimap, valueComparator);
303 }
304 }
305
306 /**
307 * Returns an immutable set multimap containing the same mappings as
308 * {@code multimap}. The generated multimap's key and value orderings
309 * correspond to the iteration ordering of the {@code multimap.asMap()} view.
310 * Repeated occurrences of an entry in the multimap after the first are
311 * ignored.
312 *
313 * <p>Despite the method name, this method attempts to avoid actually copying
314 * the data when it is safe to do so. The exact circumstances under which a
315 * copy will or will not be performed are undocumented and subject to change.
316 *
317 * @throws NullPointerException if any key or value in {@code multimap} is
318 * null
319 */
320 public static <K, V> ImmutableSetMultimap<K, V> copyOf(
321 Multimap<? extends K, ? extends V> multimap) {
322 return copyOf(multimap, null);
323 }
324
325 private static <K, V> ImmutableSetMultimap<K, V> copyOf(
326 Multimap<? extends K, ? extends V> multimap,
327 Comparator<? super V> valueComparator) {
328 checkNotNull(multimap); // eager for GWT
329 if (multimap.isEmpty() && valueComparator == null) {
330 return of();
331 }
332
333 if (multimap instanceof ImmutableSetMultimap) {
334 @SuppressWarnings("unchecked") // safe since multimap is not writable
335 ImmutableSetMultimap<K, V> kvMultimap
336 = (ImmutableSetMultimap<K, V>) multimap;
337 if (!kvMultimap.isPartialView()) {
338 return kvMultimap;
339 }
340 }
341
342 ImmutableMap.Builder<K, ImmutableSet<V>> builder = ImmutableMap.builder();
343 int size = 0;
344
345 for (Entry<? extends K, ? extends Collection<? extends V>> entry
346 : multimap.asMap().entrySet()) {
347 K key = entry.getKey();
348 Collection<? extends V> values = entry.getValue();
349 ImmutableSet<V> set = (valueComparator == null)
350 ? ImmutableSet.copyOf(values)
351 : ImmutableSortedSet.copyOf(valueComparator, values);
352 if (!set.isEmpty()) {
353 builder.put(key, set);
354 size += set.size();
355 }
356 }
357
358 return new ImmutableSetMultimap<K, V>(
359 builder.build(), size, valueComparator);
360 }
361
362 // Returned by get() when values are sorted and a missing key is provided.
363 private final transient ImmutableSortedSet<V> emptySet;
364
365 ImmutableSetMultimap(ImmutableMap<K, ImmutableSet<V>> map, int size,
366 @Nullable Comparator<? super V> valueComparator) {
367 super(map, size);
368 this.emptySet = (valueComparator == null)
369 ? null : ImmutableSortedSet.<V>emptySet(valueComparator);
370 }
371
372 // views
373
374 /**
375 * Returns an immutable set of the values for the given key. If no mappings
376 * in the multimap have the provided key, an empty immutable set is returned.
377 * The values are in the same order as the parameters used to build this
378 * multimap.
379 */
380 @Override public ImmutableSet<V> get(@Nullable K key) {
381 // This cast is safe as its type is known in constructor.
382 ImmutableSet<V> set = (ImmutableSet<V>) map.get(key);
383 if (set != null) {
384 return set;
385 } else if (emptySet != null) {
386 return emptySet;
387 } else {
388 return ImmutableSet.<V>of();
389 }
390 }
391
392 private transient ImmutableSetMultimap<V, K> inverse;
393
394 /**
395 * {@inheritDoc}
396 *
397 * <p>Because an inverse of a set multimap cannot contain multiple pairs with the same key and
398 * value, this method returns an {@code ImmutableSetMultimap} rather than the
399 * {@code ImmutableMultimap} specified in the {@code ImmutableMultimap} class.
400 *
401 * @since 11
402 */
403 @Beta
404 public ImmutableSetMultimap<V, K> inverse() {
405 ImmutableSetMultimap<V, K> result = inverse;
406 return (result == null) ? (inverse = invert()) : result;
407 }
408
409 private ImmutableSetMultimap<V, K> invert() {
410 Builder<V, K> builder = builder();
411 for (Entry<K, V> entry : entries()) {
412 builder.put(entry.getValue(), entry.getKey());
413 }
414 ImmutableSetMultimap<V, K> invertedMultimap = builder.build();
415 invertedMultimap.inverse = this;
416 return invertedMultimap;
417 }
418
419 /**
420 * Guaranteed to throw an exception and leave the multimap unmodified.
421 *
422 * @throws UnsupportedOperationException always
423 */
424 @Override public ImmutableSet<V> removeAll(Object key) {
425 throw new UnsupportedOperationException();
426 }
427
428 /**
429 * Guaranteed to throw an exception and leave the multimap unmodified.
430 *
431 * @throws UnsupportedOperationException always
432 */
433 @Override public ImmutableSet<V> replaceValues(
434 K key, Iterable<? extends V> values) {
435 throw new UnsupportedOperationException();
436 }
437
438 private transient ImmutableSet<Entry<K, V>> entries;
439
440 /**
441 * Returns an immutable collection of all key-value pairs in the multimap.
442 * Its iterator traverses the values for the first key, the values for the
443 * second key, and so on.
444 */
445 // TODO(kevinb): Fix this so that two copies of the entries are not created.
446 @Override public ImmutableSet<Entry<K, V>> entries() {
447 ImmutableSet<Entry<K, V>> result = entries;
448 return (result == null)
449 ? (entries = ImmutableSet.copyOf(super.entries()))
450 : result;
451 }
452
453 /**
454 * @serialData number of distinct keys, and then for each distinct key: the
455 * key, the number of values for that key, and the key's values
456 */
457 @GwtIncompatible("java.io.ObjectOutputStream")
458 private void writeObject(ObjectOutputStream stream) throws IOException {
459 stream.defaultWriteObject();
460 Serialization.writeMultimap(this, stream);
461 }
462
463 @GwtIncompatible("java.io.ObjectInputStream")
464 private void readObject(ObjectInputStream stream)
465 throws IOException, ClassNotFoundException {
466 stream.defaultReadObject();
467 int keyCount = stream.readInt();
468 if (keyCount < 0) {
469 throw new InvalidObjectException("Invalid key count " + keyCount);
470 }
471 ImmutableMap.Builder<Object, ImmutableSet<Object>> builder
472 = ImmutableMap.builder();
473 int tmpSize = 0;
474
475 for (int i = 0; i < keyCount; i++) {
476 Object key = stream.readObject();
477 int valueCount = stream.readInt();
478 if (valueCount <= 0) {
479 throw new InvalidObjectException("Invalid value count " + valueCount);
480 }
481
482 Object[] array = new Object[valueCount];
483 for (int j = 0; j < valueCount; j++) {
484 array[j] = stream.readObject();
485 }
486 ImmutableSet<Object> valueSet = ImmutableSet.copyOf(array);
487 if (valueSet.size() != array.length) {
488 throw new InvalidObjectException(
489 "Duplicate key-value pairs exist for key " + key);
490 }
491 builder.put(key, valueSet);
492 tmpSize += valueCount;
493 }
494
495 ImmutableMap<Object, ImmutableSet<Object>> tmpMap;
496 try {
497 tmpMap = builder.build();
498 } catch (IllegalArgumentException e) {
499 throw (InvalidObjectException)
500 new InvalidObjectException(e.getMessage()).initCause(e);
501 }
502
503 FieldSettersHolder.MAP_FIELD_SETTER.set(this, tmpMap);
504 FieldSettersHolder.SIZE_FIELD_SETTER.set(this, tmpSize);
505 }
506
507 @GwtIncompatible("not needed in emulated source.")
508 private static final long serialVersionUID = 0;
509 }