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