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
025 import java.io.IOException;
026 import java.io.InvalidObjectException;
027 import java.io.ObjectInputStream;
028 import java.io.ObjectOutputStream;
029 import java.util.Arrays;
030 import java.util.Collection;
031 import java.util.Comparator;
032 import java.util.LinkedHashMap;
033 import java.util.Map.Entry;
034 import java.util.TreeMap;
035
036 import javax.annotation.Nullable;
037
038 /**
039 * An immutable {@link SetMultimap} with reliable user-specified key and value
040 * iteration order. Does not permit null keys or values.
041 *
042 * <p>Unlike {@link Multimaps#unmodifiableSetMultimap(SetMultimap)}, which is
043 * a <i>view</i> of a separate multimap which can still change, an instance of
044 * {@code ImmutableSetMultimap} contains its own data and will <i>never</i>
045 * change. {@code ImmutableSetMultimap} is convenient for
046 * {@code public static final} multimaps ("constant multimaps") and also lets
047 * you easily make a "defensive copy" of a multimap provided to your class by
048 * a caller.
049 *
050 * <p><b>Note:</b> Although this class is not final, it cannot be subclassed as
051 * it has no public or protected constructors. Thus, instances of this class
052 * are guaranteed to be immutable.
053 *
054 * <p>See the Guava User Guide article on <a href=
055 * "http://code.google.com/p/guava-libraries/wiki/ImmutableCollectionsExplained">
056 * immutable collections</a>.
057 *
058 * @author Mike Ward
059 * @since 2.0 (imported from Google Collections Library)
060 */
061 @GwtCompatible(serializable = true, emulated = true)
062 public class ImmutableSetMultimap<K, V>
063 extends ImmutableMultimap<K, V>
064 implements SetMultimap<K, V> {
065
066 /** Returns the empty multimap. */
067 // Casting is safe because the multimap will never hold any elements.
068 @SuppressWarnings("unchecked")
069 public static <K, V> ImmutableSetMultimap<K, V> of() {
070 return (ImmutableSetMultimap<K, V>) EmptyImmutableSetMultimap.INSTANCE;
071 }
072
073 /**
074 * Returns an immutable multimap containing a single entry.
075 */
076 public static <K, V> ImmutableSetMultimap<K, V> of(K k1, V v1) {
077 ImmutableSetMultimap.Builder<K, V> builder = ImmutableSetMultimap.builder();
078 builder.put(k1, v1);
079 return builder.build();
080 }
081
082 /**
083 * Returns an immutable multimap containing the given entries, in order.
084 * Repeated occurrences of an entry (according to {@link Object#equals}) after
085 * the first are ignored.
086 */
087 public static <K, V> ImmutableSetMultimap<K, V> of(K k1, V v1, K k2, V v2) {
088 ImmutableSetMultimap.Builder<K, V> builder = ImmutableSetMultimap.builder();
089 builder.put(k1, v1);
090 builder.put(k2, v2);
091 return builder.build();
092 }
093
094 /**
095 * Returns an immutable multimap containing the given entries, in order.
096 * Repeated occurrences of an entry (according to {@link Object#equals}) after
097 * the first are ignored.
098 */
099 public static <K, V> ImmutableSetMultimap<K, V> of(
100 K k1, V v1, K k2, V v2, K k3, V v3) {
101 ImmutableSetMultimap.Builder<K, V> builder = ImmutableSetMultimap.builder();
102 builder.put(k1, v1);
103 builder.put(k2, v2);
104 builder.put(k3, v3);
105 return builder.build();
106 }
107
108 /**
109 * Returns an immutable multimap containing the given entries, in order.
110 * Repeated occurrences of an entry (according to {@link Object#equals}) after
111 * the first are ignored.
112 */
113 public static <K, V> ImmutableSetMultimap<K, V> of(
114 K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4) {
115 ImmutableSetMultimap.Builder<K, V> builder = ImmutableSetMultimap.builder();
116 builder.put(k1, v1);
117 builder.put(k2, v2);
118 builder.put(k3, v3);
119 builder.put(k4, v4);
120 return builder.build();
121 }
122
123 /**
124 * Returns an immutable multimap containing the given entries, in order.
125 * Repeated occurrences of an entry (according to {@link Object#equals}) after
126 * the first are ignored.
127 */
128 public static <K, V> ImmutableSetMultimap<K, V> of(
129 K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5) {
130 ImmutableSetMultimap.Builder<K, V> builder = ImmutableSetMultimap.builder();
131 builder.put(k1, v1);
132 builder.put(k2, v2);
133 builder.put(k3, v3);
134 builder.put(k4, v4);
135 builder.put(k5, v5);
136 return builder.build();
137 }
138
139 // looking for of() with > 5 entries? Use the builder instead.
140
141 /**
142 * Returns a new {@link Builder}.
143 */
144 public static <K, V> Builder<K, V> builder() {
145 return new Builder<K, V>();
146 }
147
148 /**
149 * Multimap for {@link ImmutableSetMultimap.Builder} that maintains key
150 * and value orderings and performs better than {@link LinkedHashMultimap}.
151 */
152 private static class BuilderMultimap<K, V> extends AbstractMultimap<K, V> {
153 BuilderMultimap() {
154 super(new LinkedHashMap<K, Collection<V>>());
155 }
156 @Override Collection<V> createCollection() {
157 return Sets.newLinkedHashSet();
158 }
159 private static final long serialVersionUID = 0;
160 }
161
162 /**
163 * Multimap for {@link ImmutableSetMultimap.Builder} that sorts keys and
164 * maintains value orderings.
165 */
166 private static class SortedKeyBuilderMultimap<K, V>
167 extends AbstractMultimap<K, V> {
168 SortedKeyBuilderMultimap(
169 Comparator<? super K> keyComparator, Multimap<K, V> multimap) {
170 super(new TreeMap<K, Collection<V>>(keyComparator));
171 putAll(multimap);
172 }
173 @Override Collection<V> createCollection() {
174 return Sets.newLinkedHashSet();
175 }
176 private static final long serialVersionUID = 0;
177 }
178
179 /**
180 * A builder for creating immutable {@code SetMultimap} instances, especially
181 * {@code public static final} multimaps ("constant multimaps"). Example:
182 * <pre> {@code
183 *
184 * static final Multimap<String, Integer> STRING_TO_INTEGER_MULTIMAP =
185 * new ImmutableSetMultimap.Builder<String, Integer>()
186 * .put("one", 1)
187 * .putAll("several", 1, 2, 3)
188 * .putAll("many", 1, 2, 3, 4, 5)
189 * .build();}</pre>
190 *
191 * Builder instances can be reused; it is safe to call {@link #build} multiple
192 * times to build multiple multimaps in series. Each multimap contains the
193 * key-value mappings in the previously created multimaps.
194 *
195 * @since 2.0 (imported from Google Collections Library)
196 */
197 public static final class Builder<K, V>
198 extends ImmutableMultimap.Builder<K, V> {
199 /**
200 * Creates a new builder. The returned builder is equivalent to the builder
201 * generated by {@link ImmutableSetMultimap#builder}.
202 */
203 public Builder() {
204 builderMultimap = new BuilderMultimap<K, V>();
205 }
206
207 /**
208 * Adds a key-value mapping to the built multimap if it is not already
209 * present.
210 */
211 @Override public Builder<K, V> put(K key, V value) {
212 builderMultimap.put(checkNotNull(key), checkNotNull(value));
213 return this;
214 }
215
216 /**
217 * Adds an entry to the built multimap if it is not already present.
218 *
219 * @since 11.0
220 */
221 @Override public Builder<K, V> put(Entry<? extends K, ? extends V> entry) {
222 builderMultimap.put(
223 checkNotNull(entry.getKey()), checkNotNull(entry.getValue()));
224 return this;
225 }
226
227 @Override public Builder<K, V> putAll(K key, Iterable<? extends V> values) {
228 Collection<V> collection = builderMultimap.get(checkNotNull(key));
229 for (V value : values) {
230 collection.add(checkNotNull(value));
231 }
232 return this;
233 }
234
235 @Override public Builder<K, V> putAll(K key, V... values) {
236 return putAll(key, Arrays.asList(values));
237 }
238
239 @Override public Builder<K, V> putAll(
240 Multimap<? extends K, ? extends V> multimap) {
241 for (Entry<? extends K, ? extends Collection<? extends V>> entry
242 : multimap.asMap().entrySet()) {
243 putAll(entry.getKey(), entry.getValue());
244 }
245 return this;
246 }
247
248 /**
249 * {@inheritDoc}
250 *
251 * @since 8.0
252 */
253 @Beta @Override
254 public Builder<K, V> orderKeysBy(Comparator<? super K> keyComparator) {
255 builderMultimap = new SortedKeyBuilderMultimap<K, V>(
256 checkNotNull(keyComparator), builderMultimap);
257 return this;
258 }
259
260 /**
261 * Specifies the ordering of the generated multimap's values for each key.
262 *
263 * <p>If this method is called, the sets returned by the {@code get()}
264 * method of the generated multimap and its {@link Multimap#asMap()} view
265 * are {@link ImmutableSortedSet} instances. However, serialization does not
266 * preserve that property, though it does maintain the key and value
267 * ordering.
268 *
269 * @since 8.0
270 */
271 // TODO: Make serialization behavior consistent.
272 @Beta @Override
273 public Builder<K, V> orderValuesBy(Comparator<? super V> valueComparator) {
274 super.orderValuesBy(valueComparator);
275 return this;
276 }
277
278 /**
279 * Returns a newly-created immutable set multimap.
280 */
281 @Override public ImmutableSetMultimap<K, V> build() {
282 return copyOf(builderMultimap, valueComparator);
283 }
284 }
285
286 /**
287 * Returns an immutable set multimap containing the same mappings as
288 * {@code multimap}. The generated multimap's key and value orderings
289 * correspond to the iteration ordering of the {@code multimap.asMap()} view.
290 * Repeated occurrences of an entry in the multimap after the first are
291 * ignored.
292 *
293 * <p>Despite the method name, this method attempts to avoid actually copying
294 * the data when it is safe to do so. The exact circumstances under which a
295 * copy will or will not be performed are undocumented and subject to change.
296 *
297 * @throws NullPointerException if any key or value in {@code multimap} is
298 * null
299 */
300 public static <K, V> ImmutableSetMultimap<K, V> copyOf(
301 Multimap<? extends K, ? extends V> multimap) {
302 return copyOf(multimap, null);
303 }
304
305 private static <K, V> ImmutableSetMultimap<K, V> copyOf(
306 Multimap<? extends K, ? extends V> multimap,
307 Comparator<? super V> valueComparator) {
308 checkNotNull(multimap); // eager for GWT
309 if (multimap.isEmpty() && valueComparator == null) {
310 return of();
311 }
312
313 if (multimap instanceof ImmutableSetMultimap) {
314 @SuppressWarnings("unchecked") // safe since multimap is not writable
315 ImmutableSetMultimap<K, V> kvMultimap
316 = (ImmutableSetMultimap<K, V>) multimap;
317 if (!kvMultimap.isPartialView()) {
318 return kvMultimap;
319 }
320 }
321
322 ImmutableMap.Builder<K, ImmutableSet<V>> builder = ImmutableMap.builder();
323 int size = 0;
324
325 for (Entry<? extends K, ? extends Collection<? extends V>> entry
326 : multimap.asMap().entrySet()) {
327 K key = entry.getKey();
328 Collection<? extends V> values = entry.getValue();
329 ImmutableSet<V> set = (valueComparator == null)
330 ? ImmutableSet.copyOf(values)
331 : ImmutableSortedSet.copyOf(valueComparator, values);
332 if (!set.isEmpty()) {
333 builder.put(key, set);
334 size += set.size();
335 }
336 }
337
338 return new ImmutableSetMultimap<K, V>(
339 builder.build(), size, valueComparator);
340 }
341
342 // Returned by get() when values are sorted and a missing key is provided.
343 private final transient ImmutableSortedSet<V> emptySet;
344
345 ImmutableSetMultimap(ImmutableMap<K, ImmutableSet<V>> map, int size,
346 @Nullable Comparator<? super V> valueComparator) {
347 super(map, size);
348 this.emptySet = (valueComparator == null)
349 ? null : ImmutableSortedSet.<V>emptySet(valueComparator);
350 }
351
352 // views
353
354 /**
355 * Returns an immutable set of the values for the given key. If no mappings
356 * in the multimap have the provided key, an empty immutable set is returned.
357 * The values are in the same order as the parameters used to build this
358 * multimap.
359 */
360 @Override public ImmutableSet<V> get(@Nullable K key) {
361 // This cast is safe as its type is known in constructor.
362 ImmutableSet<V> set = (ImmutableSet<V>) map.get(key);
363 if (set != null) {
364 return set;
365 } else if (emptySet != null) {
366 return emptySet;
367 } else {
368 return ImmutableSet.<V>of();
369 }
370 }
371
372 private transient ImmutableSetMultimap<V, K> inverse;
373
374 /**
375 * {@inheritDoc}
376 *
377 * <p>Because an inverse of a set multimap cannot contain multiple pairs with the same key and
378 * value, this method returns an {@code ImmutableSetMultimap} rather than the
379 * {@code ImmutableMultimap} specified in the {@code ImmutableMultimap} class.
380 *
381 * @since 11
382 */
383 @Beta
384 public ImmutableSetMultimap<V, K> inverse() {
385 ImmutableSetMultimap<V, K> result = inverse;
386 return (result == null) ? (inverse = invert()) : result;
387 }
388
389 private ImmutableSetMultimap<V, K> invert() {
390 Builder<V, K> builder = builder();
391 for (Entry<K, V> entry : entries()) {
392 builder.put(entry.getValue(), entry.getKey());
393 }
394 ImmutableSetMultimap<V, K> invertedMultimap = builder.build();
395 invertedMultimap.inverse = this;
396 return invertedMultimap;
397 }
398
399 /**
400 * Guaranteed to throw an exception and leave the multimap unmodified.
401 *
402 * @throws UnsupportedOperationException always
403 */
404 @Override public ImmutableSet<V> removeAll(Object key) {
405 throw new UnsupportedOperationException();
406 }
407
408 /**
409 * Guaranteed to throw an exception and leave the multimap unmodified.
410 *
411 * @throws UnsupportedOperationException always
412 */
413 @Override public ImmutableSet<V> replaceValues(
414 K key, Iterable<? extends V> values) {
415 throw new UnsupportedOperationException();
416 }
417
418 private transient ImmutableSet<Entry<K, V>> entries;
419
420 /**
421 * Returns an immutable collection of all key-value pairs in the multimap.
422 * Its iterator traverses the values for the first key, the values for the
423 * second key, and so on.
424 */
425 // TODO(kevinb): Fix this so that two copies of the entries are not created.
426 @Override public ImmutableSet<Entry<K, V>> entries() {
427 ImmutableSet<Entry<K, V>> result = entries;
428 return (result == null)
429 ? (entries = ImmutableSet.copyOf(super.entries()))
430 : result;
431 }
432
433 /**
434 * @serialData number of distinct keys, and then for each distinct key: the
435 * key, the number of values for that key, and the key's values
436 */
437 @GwtIncompatible("java.io.ObjectOutputStream")
438 private void writeObject(ObjectOutputStream stream) throws IOException {
439 stream.defaultWriteObject();
440 Serialization.writeMultimap(this, stream);
441 }
442
443 @GwtIncompatible("java.io.ObjectInputStream")
444 private void readObject(ObjectInputStream stream)
445 throws IOException, ClassNotFoundException {
446 stream.defaultReadObject();
447 int keyCount = stream.readInt();
448 if (keyCount < 0) {
449 throw new InvalidObjectException("Invalid key count " + keyCount);
450 }
451 ImmutableMap.Builder<Object, ImmutableSet<Object>> builder
452 = ImmutableMap.builder();
453 int tmpSize = 0;
454
455 for (int i = 0; i < keyCount; i++) {
456 Object key = stream.readObject();
457 int valueCount = stream.readInt();
458 if (valueCount <= 0) {
459 throw new InvalidObjectException("Invalid value count " + valueCount);
460 }
461
462 Object[] array = new Object[valueCount];
463 for (int j = 0; j < valueCount; j++) {
464 array[j] = stream.readObject();
465 }
466 ImmutableSet<Object> valueSet = ImmutableSet.copyOf(array);
467 if (valueSet.size() != array.length) {
468 throw new InvalidObjectException(
469 "Duplicate key-value pairs exist for key " + key);
470 }
471 builder.put(key, valueSet);
472 tmpSize += valueCount;
473 }
474
475 ImmutableMap<Object, ImmutableSet<Object>> tmpMap;
476 try {
477 tmpMap = builder.build();
478 } catch (IllegalArgumentException e) {
479 throw (InvalidObjectException)
480 new InvalidObjectException(e.getMessage()).initCause(e);
481 }
482
483 FieldSettersHolder.MAP_FIELD_SETTER.set(this, tmpMap);
484 FieldSettersHolder.SIZE_FIELD_SETTER.set(this, tmpSize);
485 }
486
487 @GwtIncompatible("not needed in emulated source.")
488 private static final long serialVersionUID = 0;
489 }