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 017package com.google.common.collect; 018 019import static com.google.common.base.Preconditions.checkNotNull; 020 021import com.google.common.annotations.Beta; 022import com.google.common.annotations.GwtCompatible; 023import com.google.common.annotations.GwtIncompatible; 024import com.google.common.base.MoreObjects; 025import com.google.errorprone.annotations.CanIgnoreReturnValue; 026import com.google.errorprone.annotations.DoNotCall; 027import com.google.errorprone.annotations.concurrent.LazyInit; 028import com.google.j2objc.annotations.RetainedWith; 029import com.google.j2objc.annotations.Weak; 030import java.io.IOException; 031import java.io.InvalidObjectException; 032import java.io.ObjectInputStream; 033import java.io.ObjectOutputStream; 034import java.util.Arrays; 035import java.util.Collection; 036import java.util.Comparator; 037import java.util.Map; 038import java.util.Map.Entry; 039import javax.annotation.CheckForNull; 040 041/** 042 * A {@link SetMultimap} whose contents will never change, with many other important properties 043 * detailed at {@link ImmutableCollection}. 044 * 045 * <p><b>Warning:</b> As in all {@link SetMultimap}s, do not modify either a key <i>or a value</i> 046 * of a {@code ImmutableSetMultimap} in a way that affects its {@link Object#equals} behavior. 047 * Undefined behavior and bugs will result. 048 * 049 * <p>See the Guava User Guide article on <a href= 050 * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained"> immutable collections</a>. 051 * 052 * @author Mike Ward 053 * @since 2.0 054 */ 055@GwtCompatible(serializable = true, emulated = true) 056@ElementTypesAreNonnullByDefault 057public class ImmutableSetMultimap<K, V> extends ImmutableMultimap<K, V> 058 implements SetMultimap<K, V> { 059 060 /** 061 * Returns the empty multimap. 062 * 063 * <p><b>Performance note:</b> the instance returned is a singleton. 064 */ 065 // Casting is safe because the multimap will never hold any elements. 066 @SuppressWarnings("unchecked") 067 public static <K, V> ImmutableSetMultimap<K, V> of() { 068 return (ImmutableSetMultimap<K, V>) EmptyImmutableSetMultimap.INSTANCE; 069 } 070 071 /** Returns an immutable multimap containing a single entry. */ 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. Repeated occurrences of 080 * an entry (according to {@link Object#equals}) after the first are ignored. 081 */ 082 public static <K, V> ImmutableSetMultimap<K, V> of(K k1, V v1, K k2, V v2) { 083 ImmutableSetMultimap.Builder<K, V> builder = ImmutableSetMultimap.builder(); 084 builder.put(k1, v1); 085 builder.put(k2, v2); 086 return builder.build(); 087 } 088 089 /** 090 * Returns an immutable multimap containing the given entries, in order. Repeated occurrences of 091 * an entry (according to {@link Object#equals}) after the first are ignored. 092 */ 093 public static <K, V> ImmutableSetMultimap<K, V> of(K k1, V v1, K k2, V v2, K k3, V v3) { 094 ImmutableSetMultimap.Builder<K, V> builder = ImmutableSetMultimap.builder(); 095 builder.put(k1, v1); 096 builder.put(k2, v2); 097 builder.put(k3, v3); 098 return builder.build(); 099 } 100 101 /** 102 * Returns an immutable multimap containing the given entries, in order. Repeated occurrences of 103 * an entry (according to {@link Object#equals}) after the first are ignored. 104 */ 105 public static <K, V> ImmutableSetMultimap<K, V> of( 106 K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4) { 107 ImmutableSetMultimap.Builder<K, V> builder = ImmutableSetMultimap.builder(); 108 builder.put(k1, v1); 109 builder.put(k2, v2); 110 builder.put(k3, v3); 111 builder.put(k4, v4); 112 return builder.build(); 113 } 114 115 /** 116 * Returns an immutable multimap containing the given entries, in order. Repeated occurrences of 117 * an entry (according to {@link Object#equals}) after the first are ignored. 118 */ 119 public static <K, V> ImmutableSetMultimap<K, V> of( 120 K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5) { 121 ImmutableSetMultimap.Builder<K, V> builder = ImmutableSetMultimap.builder(); 122 builder.put(k1, v1); 123 builder.put(k2, v2); 124 builder.put(k3, v3); 125 builder.put(k4, v4); 126 builder.put(k5, v5); 127 return builder.build(); 128 } 129 130 // looking for of() with > 5 entries? Use the builder instead. 131 132 /** Returns a new {@link Builder}. */ 133 public static <K, V> Builder<K, V> builder() { 134 return new Builder<>(); 135 } 136 137 /** 138 * A builder for creating immutable {@code SetMultimap} instances, especially {@code public static 139 * final} multimaps ("constant multimaps"). Example: 140 * 141 * <pre>{@code 142 * static final Multimap<String, Integer> STRING_TO_INTEGER_MULTIMAP = 143 * new ImmutableSetMultimap.Builder<String, Integer>() 144 * .put("one", 1) 145 * .putAll("several", 1, 2, 3) 146 * .putAll("many", 1, 2, 3, 4, 5) 147 * .build(); 148 * }</pre> 149 * 150 * <p>Builder instances can be reused; it is safe to call {@link #build} multiple times to build 151 * multiple multimaps in series. Each multimap contains the key-value mappings in the previously 152 * created multimaps. 153 * 154 * @since 2.0 155 */ 156 public static final class Builder<K, V> extends ImmutableMultimap.Builder<K, V> { 157 /** 158 * Creates a new builder. The returned builder is equivalent to the builder generated by {@link 159 * ImmutableSetMultimap#builder}. 160 */ 161 public Builder() { 162 super(); 163 } 164 165 @Override 166 Collection<V> newMutableValueCollection() { 167 return Platform.preservesInsertionOrderOnAddsSet(); 168 } 169 170 /** Adds a key-value mapping to the built multimap if it is not already present. */ 171 @CanIgnoreReturnValue 172 @Override 173 public Builder<K, V> put(K key, V value) { 174 super.put(key, value); 175 return this; 176 } 177 178 /** 179 * Adds an entry to the built multimap if it is not already present. 180 * 181 * @since 11.0 182 */ 183 @CanIgnoreReturnValue 184 @Override 185 public Builder<K, V> put(Entry<? extends K, ? extends V> entry) { 186 super.put(entry); 187 return this; 188 } 189 190 /** 191 * {@inheritDoc} 192 * 193 * @since 19.0 194 */ 195 @CanIgnoreReturnValue 196 @Beta 197 @Override 198 public Builder<K, V> putAll(Iterable<? extends Entry<? extends K, ? extends V>> entries) { 199 super.putAll(entries); 200 return this; 201 } 202 203 @CanIgnoreReturnValue 204 @Override 205 public Builder<K, V> putAll(K key, Iterable<? extends V> values) { 206 super.putAll(key, values); 207 return this; 208 } 209 210 @CanIgnoreReturnValue 211 @Override 212 public Builder<K, V> putAll(K key, V... values) { 213 return putAll(key, Arrays.asList(values)); 214 } 215 216 @CanIgnoreReturnValue 217 @Override 218 public Builder<K, V> putAll(Multimap<? extends K, ? extends V> multimap) { 219 for (Entry<? extends K, ? extends Collection<? extends V>> entry : 220 multimap.asMap().entrySet()) { 221 putAll(entry.getKey(), entry.getValue()); 222 } 223 return this; 224 } 225 226 @CanIgnoreReturnValue 227 @Override 228 Builder<K, V> combine(ImmutableMultimap.Builder<K, V> other) { 229 super.combine(other); 230 return this; 231 } 232 233 /** 234 * {@inheritDoc} 235 * 236 * @since 8.0 237 */ 238 @CanIgnoreReturnValue 239 @Override 240 public Builder<K, V> orderKeysBy(Comparator<? super K> keyComparator) { 241 super.orderKeysBy(keyComparator); 242 return this; 243 } 244 245 /** 246 * Specifies the ordering of the generated multimap's values for each key. 247 * 248 * <p>If this method is called, the sets returned by the {@code get()} method of the generated 249 * multimap and its {@link Multimap#asMap()} view are {@link ImmutableSortedSet} instances. 250 * However, serialization does not preserve that property, though it does maintain the key and 251 * value ordering. 252 * 253 * @since 8.0 254 */ 255 // TODO: Make serialization behavior consistent. 256 @CanIgnoreReturnValue 257 @Override 258 public Builder<K, V> orderValuesBy(Comparator<? super V> valueComparator) { 259 super.orderValuesBy(valueComparator); 260 return this; 261 } 262 263 /** Returns a newly-created immutable set multimap. */ 264 @Override 265 public ImmutableSetMultimap<K, V> build() { 266 Collection<Map.Entry<K, Collection<V>>> mapEntries = builderMap.entrySet(); 267 if (keyComparator != null) { 268 mapEntries = Ordering.from(keyComparator).<K>onKeys().immutableSortedCopy(mapEntries); 269 } 270 return fromMapEntries(mapEntries, valueComparator); 271 } 272 } 273 274 /** 275 * Returns an immutable set multimap containing the same mappings as {@code multimap}. The 276 * generated multimap's key and value orderings correspond to the iteration ordering of the {@code 277 * multimap.asMap()} view. Repeated occurrences of an entry in the multimap after the first are 278 * ignored. 279 * 280 * <p>Despite the method name, this method attempts to avoid actually copying the data when it is 281 * safe to do so. The exact circumstances under which a copy will or will not be performed are 282 * undocumented and subject to change. 283 * 284 * @throws NullPointerException if any key or value in {@code multimap} is null 285 */ 286 public static <K, V> ImmutableSetMultimap<K, V> copyOf( 287 Multimap<? extends K, ? extends V> multimap) { 288 return copyOf(multimap, null); 289 } 290 291 private static <K, V> ImmutableSetMultimap<K, V> copyOf( 292 Multimap<? extends K, ? extends V> multimap, 293 @CheckForNull Comparator<? super V> valueComparator) { 294 checkNotNull(multimap); // eager for GWT 295 if (multimap.isEmpty() && valueComparator == null) { 296 return of(); 297 } 298 299 if (multimap instanceof ImmutableSetMultimap) { 300 @SuppressWarnings("unchecked") // safe since multimap is not writable 301 ImmutableSetMultimap<K, V> kvMultimap = (ImmutableSetMultimap<K, V>) multimap; 302 if (!kvMultimap.isPartialView()) { 303 return kvMultimap; 304 } 305 } 306 307 return fromMapEntries(multimap.asMap().entrySet(), valueComparator); 308 } 309 310 /** 311 * Returns an immutable multimap containing the specified entries. The returned multimap iterates 312 * over keys in the order they were first encountered in the input, and the values for each key 313 * are iterated in the order they were encountered. If two values for the same key are {@linkplain 314 * Object#equals equal}, the first value encountered is used. 315 * 316 * @throws NullPointerException if any key, value, or entry is null 317 * @since 19.0 318 */ 319 @Beta 320 public static <K, V> ImmutableSetMultimap<K, V> copyOf( 321 Iterable<? extends Entry<? extends K, ? extends V>> entries) { 322 return new Builder<K, V>().putAll(entries).build(); 323 } 324 325 /** Creates an ImmutableSetMultimap from an asMap.entrySet. */ 326 static <K, V> ImmutableSetMultimap<K, V> fromMapEntries( 327 Collection<? extends Map.Entry<? extends K, ? extends Collection<? extends V>>> mapEntries, 328 @CheckForNull Comparator<? super V> valueComparator) { 329 if (mapEntries.isEmpty()) { 330 return of(); 331 } 332 ImmutableMap.Builder<K, ImmutableSet<V>> builder = 333 new ImmutableMap.Builder<>(mapEntries.size()); 334 int size = 0; 335 336 for (Entry<? extends K, ? extends Collection<? extends V>> entry : mapEntries) { 337 K key = entry.getKey(); 338 Collection<? extends V> values = entry.getValue(); 339 ImmutableSet<V> set = valueSet(valueComparator, values); 340 if (!set.isEmpty()) { 341 builder.put(key, set); 342 size += set.size(); 343 } 344 } 345 346 return new ImmutableSetMultimap<>(builder.build(), size, valueComparator); 347 } 348 349 /** 350 * Returned by get() when a missing key is provided. Also holds the comparator, if any, used for 351 * values. 352 */ 353 private final transient ImmutableSet<V> emptySet; 354 355 ImmutableSetMultimap( 356 ImmutableMap<K, ImmutableSet<V>> map, 357 int size, 358 @CheckForNull Comparator<? super V> valueComparator) { 359 super(map, size); 360 this.emptySet = emptySet(valueComparator); 361 } 362 363 // views 364 365 /** 366 * Returns an immutable set of the values for the given key. If no mappings in the multimap have 367 * the provided key, an empty immutable set is returned. The values are in the same order as the 368 * parameters used to build this multimap. 369 */ 370 @Override 371 public ImmutableSet<V> get(K key) { 372 // This cast is safe as its type is known in constructor. 373 ImmutableSet<V> set = (ImmutableSet<V>) map.get(key); 374 return MoreObjects.firstNonNull(set, emptySet); 375 } 376 377 @LazyInit @RetainedWith @CheckForNull private transient ImmutableSetMultimap<V, K> inverse; 378 379 /** 380 * {@inheritDoc} 381 * 382 * <p>Because an inverse of a set multimap cannot contain multiple pairs with the same key and 383 * value, this method returns an {@code ImmutableSetMultimap} rather than the {@code 384 * ImmutableMultimap} specified in the {@code ImmutableMultimap} class. 385 */ 386 @Override 387 public ImmutableSetMultimap<V, K> inverse() { 388 ImmutableSetMultimap<V, K> result = inverse; 389 return (result == null) ? (inverse = invert()) : result; 390 } 391 392 private ImmutableSetMultimap<V, K> invert() { 393 Builder<V, K> builder = builder(); 394 for (Entry<K, V> entry : entries()) { 395 builder.put(entry.getValue(), entry.getKey()); 396 } 397 ImmutableSetMultimap<V, K> invertedMultimap = builder.build(); 398 invertedMultimap.inverse = this; 399 return invertedMultimap; 400 } 401 402 /** 403 * Guaranteed to throw an exception and leave the multimap unmodified. 404 * 405 * @throws UnsupportedOperationException always 406 * @deprecated Unsupported operation. 407 */ 408 @CanIgnoreReturnValue 409 @Deprecated 410 @Override 411 @DoNotCall("Always throws UnsupportedOperationException") 412 public final ImmutableSet<V> removeAll(@CheckForNull Object key) { 413 throw new UnsupportedOperationException(); 414 } 415 416 /** 417 * Guaranteed to throw an exception and leave the multimap unmodified. 418 * 419 * @throws UnsupportedOperationException always 420 * @deprecated Unsupported operation. 421 */ 422 @CanIgnoreReturnValue 423 @Deprecated 424 @Override 425 @DoNotCall("Always throws UnsupportedOperationException") 426 public final ImmutableSet<V> replaceValues(K key, Iterable<? extends V> values) { 427 throw new UnsupportedOperationException(); 428 } 429 430 @LazyInit @RetainedWith @CheckForNull private transient ImmutableSet<Entry<K, V>> entries; 431 432 /** 433 * Returns an immutable collection of all key-value pairs in the multimap. Its iterator traverses 434 * the values for the first key, the values for the second key, and so on. 435 */ 436 @Override 437 public ImmutableSet<Entry<K, V>> entries() { 438 ImmutableSet<Entry<K, V>> result = entries; 439 return result == null ? (entries = new EntrySet<>(this)) : result; 440 } 441 442 private static final class EntrySet<K, V> extends ImmutableSet<Entry<K, V>> { 443 @Weak private final transient ImmutableSetMultimap<K, V> multimap; 444 445 EntrySet(ImmutableSetMultimap<K, V> multimap) { 446 this.multimap = multimap; 447 } 448 449 @Override 450 public boolean contains(@CheckForNull Object object) { 451 if (object instanceof Entry) { 452 Entry<?, ?> entry = (Entry<?, ?>) object; 453 return multimap.containsEntry(entry.getKey(), entry.getValue()); 454 } 455 return false; 456 } 457 458 @Override 459 public int size() { 460 return multimap.size(); 461 } 462 463 @Override 464 public UnmodifiableIterator<Entry<K, V>> iterator() { 465 return multimap.entryIterator(); 466 } 467 468 @Override 469 boolean isPartialView() { 470 return false; 471 } 472 } 473 474 private static <V> ImmutableSet<V> valueSet( 475 @CheckForNull Comparator<? super V> valueComparator, Collection<? extends V> values) { 476 return (valueComparator == null) 477 ? ImmutableSet.copyOf(values) 478 : ImmutableSortedSet.copyOf(valueComparator, values); 479 } 480 481 private static <V> ImmutableSet<V> emptySet(@CheckForNull Comparator<? super V> valueComparator) { 482 return (valueComparator == null) 483 ? ImmutableSet.<V>of() 484 : ImmutableSortedSet.<V>emptySet(valueComparator); 485 } 486 487 private static <V> ImmutableSet.Builder<V> valuesBuilder( 488 @CheckForNull Comparator<? super V> valueComparator) { 489 return (valueComparator == null) 490 ? new ImmutableSet.Builder<V>() 491 : new ImmutableSortedSet.Builder<V>(valueComparator); 492 } 493 494 /** 495 * @serialData number of distinct keys, and then for each distinct key: the key, the number of 496 * values for that key, and the key's values 497 */ 498 @GwtIncompatible // java.io.ObjectOutputStream 499 private void writeObject(ObjectOutputStream stream) throws IOException { 500 stream.defaultWriteObject(); 501 stream.writeObject(valueComparator()); 502 Serialization.writeMultimap(this, stream); 503 } 504 505 @CheckForNull 506 Comparator<? super V> valueComparator() { 507 return emptySet instanceof ImmutableSortedSet 508 ? ((ImmutableSortedSet<V>) emptySet).comparator() 509 : null; 510 } 511 512 @GwtIncompatible // java serialization 513 private static final class SetFieldSettersHolder { 514 static final Serialization.FieldSetter<ImmutableSetMultimap> EMPTY_SET_FIELD_SETTER = 515 Serialization.getFieldSetter(ImmutableSetMultimap.class, "emptySet"); 516 } 517 518 @GwtIncompatible // java.io.ObjectInputStream 519 // Serialization type safety is at the caller's mercy. 520 @SuppressWarnings("unchecked") 521 private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException { 522 stream.defaultReadObject(); 523 Comparator<Object> valueComparator = (Comparator<Object>) stream.readObject(); 524 int keyCount = stream.readInt(); 525 if (keyCount < 0) { 526 throw new InvalidObjectException("Invalid key count " + keyCount); 527 } 528 ImmutableMap.Builder<Object, ImmutableSet<Object>> builder = ImmutableMap.builder(); 529 int tmpSize = 0; 530 531 for (int i = 0; i < keyCount; i++) { 532 Object key = stream.readObject(); 533 int valueCount = stream.readInt(); 534 if (valueCount <= 0) { 535 throw new InvalidObjectException("Invalid value count " + valueCount); 536 } 537 538 ImmutableSet.Builder<Object> valuesBuilder = valuesBuilder(valueComparator); 539 for (int j = 0; j < valueCount; j++) { 540 valuesBuilder.add(stream.readObject()); 541 } 542 ImmutableSet<Object> valueSet = valuesBuilder.build(); 543 if (valueSet.size() != valueCount) { 544 throw new InvalidObjectException("Duplicate key-value pairs exist for key " + key); 545 } 546 builder.put(key, valueSet); 547 tmpSize += valueCount; 548 } 549 550 ImmutableMap<Object, ImmutableSet<Object>> tmpMap; 551 try { 552 tmpMap = builder.build(); 553 } catch (IllegalArgumentException e) { 554 throw (InvalidObjectException) new InvalidObjectException(e.getMessage()).initCause(e); 555 } 556 557 FieldSettersHolder.MAP_FIELD_SETTER.set(this, tmpMap); 558 FieldSettersHolder.SIZE_FIELD_SETTER.set(this, tmpSize); 559 SetFieldSettersHolder.EMPTY_SET_FIELD_SETTER.set(this, emptySet(valueComparator)); 560 } 561 562 @GwtIncompatible // not needed in emulated source. 563 private static final long serialVersionUID = 0; 564}