001/* 002 * Copyright (C) 2008 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 com.google.common.annotations.GwtCompatible; 020import com.google.common.annotations.GwtIncompatible; 021import com.google.common.annotations.J2ktIncompatible; 022import com.google.errorprone.annotations.CanIgnoreReturnValue; 023import com.google.errorprone.annotations.DoNotCall; 024import com.google.errorprone.annotations.concurrent.LazyInit; 025import com.google.j2objc.annotations.RetainedWith; 026import java.io.IOException; 027import java.io.InvalidObjectException; 028import java.io.ObjectInputStream; 029import java.io.ObjectOutputStream; 030import java.util.Collection; 031import java.util.Comparator; 032import java.util.Map; 033import java.util.Map.Entry; 034import java.util.function.Function; 035import java.util.stream.Collector; 036import java.util.stream.Stream; 037import javax.annotation.CheckForNull; 038import org.checkerframework.checker.nullness.qual.Nullable; 039 040/** 041 * A {@link ListMultimap} whose contents will never change, with many other important properties 042 * detailed at {@link ImmutableCollection}. 043 * 044 * <p>See the Guava User Guide article on <a href= 045 * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained">immutable collections</a>. 046 * 047 * @author Jared Levy 048 * @since 2.0 049 */ 050@GwtCompatible(serializable = true, emulated = true) 051@ElementTypesAreNonnullByDefault 052public class ImmutableListMultimap<K, V> extends ImmutableMultimap<K, V> 053 implements ListMultimap<K, V> { 054 /** 055 * Returns a {@link Collector} that accumulates elements into an {@code ImmutableListMultimap} 056 * whose keys and values are the result of applying the provided mapping functions to the input 057 * elements. 058 * 059 * <p>For streams with defined encounter order (as defined in the Ordering section of the {@link 060 * java.util.stream} Javadoc), that order is preserved, but entries are <a 061 * href="ImmutableMultimap.html#iteration">grouped by key</a>. 062 * 063 * <p>Example: 064 * 065 * <pre>{@code 066 * static final Multimap<Character, String> FIRST_LETTER_MULTIMAP = 067 * Stream.of("banana", "apple", "carrot", "asparagus", "cherry") 068 * .collect(toImmutableListMultimap(str -> str.charAt(0), str -> str.substring(1))); 069 * 070 * // is equivalent to 071 * 072 * static final Multimap<Character, String> FIRST_LETTER_MULTIMAP = 073 * new ImmutableListMultimap.Builder<Character, String>() 074 * .put('b', "anana") 075 * .putAll('a', "pple", "sparagus") 076 * .putAll('c', "arrot", "herry") 077 * .build(); 078 * }</pre> 079 * 080 * @since 21.0 081 */ 082 public static <T extends @Nullable Object, K, V> 083 Collector<T, ?, ImmutableListMultimap<K, V>> toImmutableListMultimap( 084 Function<? super T, ? extends K> keyFunction, 085 Function<? super T, ? extends V> valueFunction) { 086 return CollectCollectors.toImmutableListMultimap(keyFunction, valueFunction); 087 } 088 089 /** 090 * Returns a {@code Collector} accumulating entries into an {@code ImmutableListMultimap}. Each 091 * input element is mapped to a key and a stream of values, each of which are put into the 092 * resulting {@code Multimap}, in the encounter order of the stream and the encounter order of the 093 * streams of values. 094 * 095 * <p>Example: 096 * 097 * <pre>{@code 098 * static final ImmutableListMultimap<Character, Character> FIRST_LETTER_MULTIMAP = 099 * Stream.of("banana", "apple", "carrot", "asparagus", "cherry") 100 * .collect( 101 * flatteningToImmutableListMultimap( 102 * str -> str.charAt(0), 103 * str -> str.substring(1).chars().mapToObj(c -> (char) c)); 104 * 105 * // is equivalent to 106 * 107 * static final ImmutableListMultimap<Character, Character> FIRST_LETTER_MULTIMAP = 108 * ImmutableListMultimap.<Character, Character>builder() 109 * .putAll('b', Arrays.asList('a', 'n', 'a', 'n', 'a')) 110 * .putAll('a', Arrays.asList('p', 'p', 'l', 'e')) 111 * .putAll('c', Arrays.asList('a', 'r', 'r', 'o', 't')) 112 * .putAll('a', Arrays.asList('s', 'p', 'a', 'r', 'a', 'g', 'u', 's')) 113 * .putAll('c', Arrays.asList('h', 'e', 'r', 'r', 'y')) 114 * .build(); 115 * } 116 * }</pre> 117 * 118 * @since 21.0 119 */ 120 public static <T extends @Nullable Object, K, V> 121 Collector<T, ?, ImmutableListMultimap<K, V>> flatteningToImmutableListMultimap( 122 Function<? super T, ? extends K> keyFunction, 123 Function<? super T, ? extends Stream<? extends V>> valuesFunction) { 124 return CollectCollectors.flatteningToImmutableListMultimap(keyFunction, valuesFunction); 125 } 126 127 /** 128 * Returns the empty multimap. 129 * 130 * <p><b>Performance note:</b> the instance returned is a singleton. 131 */ 132 // Casting is safe because the multimap will never hold any elements. 133 @SuppressWarnings("unchecked") 134 public static <K, V> ImmutableListMultimap<K, V> of() { 135 return (ImmutableListMultimap<K, V>) EmptyImmutableListMultimap.INSTANCE; 136 } 137 138 /** Returns an immutable multimap containing a single entry. */ 139 public static <K, V> ImmutableListMultimap<K, V> of(K k1, V v1) { 140 ImmutableListMultimap.Builder<K, V> builder = ImmutableListMultimap.builder(); 141 builder.put(k1, v1); 142 return builder.build(); 143 } 144 145 /** Returns an immutable multimap containing the given entries, in order. */ 146 public static <K, V> ImmutableListMultimap<K, V> of(K k1, V v1, K k2, V v2) { 147 ImmutableListMultimap.Builder<K, V> builder = ImmutableListMultimap.builder(); 148 builder.put(k1, v1); 149 builder.put(k2, v2); 150 return builder.build(); 151 } 152 153 /** Returns an immutable multimap containing the given entries, in order. */ 154 public static <K, V> ImmutableListMultimap<K, V> of(K k1, V v1, K k2, V v2, K k3, V v3) { 155 ImmutableListMultimap.Builder<K, V> builder = ImmutableListMultimap.builder(); 156 builder.put(k1, v1); 157 builder.put(k2, v2); 158 builder.put(k3, v3); 159 return builder.build(); 160 } 161 162 /** Returns an immutable multimap containing the given entries, in order. */ 163 public static <K, V> ImmutableListMultimap<K, V> of( 164 K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4) { 165 ImmutableListMultimap.Builder<K, V> builder = ImmutableListMultimap.builder(); 166 builder.put(k1, v1); 167 builder.put(k2, v2); 168 builder.put(k3, v3); 169 builder.put(k4, v4); 170 return builder.build(); 171 } 172 173 /** Returns an immutable multimap containing the given entries, in order. */ 174 public static <K, V> ImmutableListMultimap<K, V> of( 175 K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5) { 176 ImmutableListMultimap.Builder<K, V> builder = ImmutableListMultimap.builder(); 177 builder.put(k1, v1); 178 builder.put(k2, v2); 179 builder.put(k3, v3); 180 builder.put(k4, v4); 181 builder.put(k5, v5); 182 return builder.build(); 183 } 184 185 // looking for of() with > 5 entries? Use the builder instead. 186 187 /** 188 * Returns a new builder. The generated builder is equivalent to the builder created by the {@link 189 * Builder} constructor. 190 */ 191 public static <K, V> Builder<K, V> builder() { 192 return new Builder<>(); 193 } 194 195 /** 196 * A builder for creating immutable {@code ListMultimap} instances, especially {@code public 197 * static final} multimaps ("constant multimaps"). Example: 198 * 199 * <pre>{@code 200 * static final Multimap<String, Integer> STRING_TO_INTEGER_MULTIMAP = 201 * new ImmutableListMultimap.Builder<String, Integer>() 202 * .put("one", 1) 203 * .putAll("several", 1, 2, 3) 204 * .putAll("many", 1, 2, 3, 4, 5) 205 * .build(); 206 * }</pre> 207 * 208 * <p>Builder instances can be reused; it is safe to call {@link #build} multiple times to build 209 * multiple multimaps in series. Each multimap contains the key-value mappings in the previously 210 * created multimaps. 211 * 212 * @since 2.0 213 */ 214 public static final class Builder<K, V> extends ImmutableMultimap.Builder<K, V> { 215 /** 216 * Creates a new builder. The returned builder is equivalent to the builder generated by {@link 217 * ImmutableListMultimap#builder}. 218 */ 219 public Builder() {} 220 221 @CanIgnoreReturnValue 222 @Override 223 public Builder<K, V> put(K key, V value) { 224 super.put(key, value); 225 return this; 226 } 227 228 /** 229 * {@inheritDoc} 230 * 231 * @since 11.0 232 */ 233 @CanIgnoreReturnValue 234 @Override 235 public Builder<K, V> put(Entry<? extends K, ? extends V> entry) { 236 super.put(entry); 237 return this; 238 } 239 240 /** 241 * {@inheritDoc} 242 * 243 * @since 19.0 244 */ 245 @CanIgnoreReturnValue 246 @Override 247 public Builder<K, V> putAll(Iterable<? extends Entry<? extends K, ? extends V>> entries) { 248 super.putAll(entries); 249 return this; 250 } 251 252 @CanIgnoreReturnValue 253 @Override 254 public Builder<K, V> putAll(K key, Iterable<? extends V> values) { 255 super.putAll(key, values); 256 return this; 257 } 258 259 @CanIgnoreReturnValue 260 @Override 261 public Builder<K, V> putAll(K key, V... values) { 262 super.putAll(key, values); 263 return this; 264 } 265 266 @CanIgnoreReturnValue 267 @Override 268 public Builder<K, V> putAll(Multimap<? extends K, ? extends V> multimap) { 269 super.putAll(multimap); 270 return this; 271 } 272 273 @CanIgnoreReturnValue 274 @Override 275 Builder<K, V> combine(ImmutableMultimap.Builder<K, V> other) { 276 super.combine(other); 277 return this; 278 } 279 280 /** 281 * {@inheritDoc} 282 * 283 * @since 8.0 284 */ 285 @CanIgnoreReturnValue 286 @Override 287 public Builder<K, V> orderKeysBy(Comparator<? super K> keyComparator) { 288 super.orderKeysBy(keyComparator); 289 return this; 290 } 291 292 /** 293 * {@inheritDoc} 294 * 295 * @since 8.0 296 */ 297 @CanIgnoreReturnValue 298 @Override 299 public Builder<K, V> orderValuesBy(Comparator<? super V> valueComparator) { 300 super.orderValuesBy(valueComparator); 301 return this; 302 } 303 304 /** Returns a newly-created immutable list multimap. */ 305 @Override 306 public ImmutableListMultimap<K, V> build() { 307 return (ImmutableListMultimap<K, V>) super.build(); 308 } 309 } 310 311 /** 312 * Returns an immutable multimap containing the same mappings as {@code multimap}. The generated 313 * multimap's key and value orderings correspond to the iteration ordering of the {@code 314 * multimap.asMap()} view. 315 * 316 * <p>Despite the method name, this method attempts to avoid actually copying the data when it is 317 * safe to do so. The exact circumstances under which a copy will or will not be performed are 318 * undocumented and subject to change. 319 * 320 * @throws NullPointerException if any key or value in {@code multimap} is null 321 */ 322 public static <K, V> ImmutableListMultimap<K, V> copyOf( 323 Multimap<? extends K, ? extends V> multimap) { 324 if (multimap.isEmpty()) { 325 return of(); 326 } 327 328 // TODO(lowasser): copy ImmutableSetMultimap by using asList() on the sets 329 if (multimap instanceof ImmutableListMultimap) { 330 @SuppressWarnings("unchecked") // safe since multimap is not writable 331 ImmutableListMultimap<K, V> kvMultimap = (ImmutableListMultimap<K, V>) multimap; 332 if (!kvMultimap.isPartialView()) { 333 return kvMultimap; 334 } 335 } 336 337 return fromMapEntries(multimap.asMap().entrySet(), null); 338 } 339 340 /** 341 * Returns an immutable multimap containing the specified entries. The returned multimap iterates 342 * over keys in the order they were first encountered in the input, and the values for each key 343 * are iterated in the order they were encountered. 344 * 345 * @throws NullPointerException if any key, value, or entry is null 346 * @since 19.0 347 */ 348 public static <K, V> ImmutableListMultimap<K, V> copyOf( 349 Iterable<? extends Entry<? extends K, ? extends V>> entries) { 350 return new Builder<K, V>().putAll(entries).build(); 351 } 352 353 /** Creates an ImmutableListMultimap from an asMap.entrySet. */ 354 static <K, V> ImmutableListMultimap<K, V> fromMapEntries( 355 Collection<? extends Map.Entry<? extends K, ? extends Collection<? extends V>>> mapEntries, 356 @CheckForNull Comparator<? super V> valueComparator) { 357 if (mapEntries.isEmpty()) { 358 return of(); 359 } 360 ImmutableMap.Builder<K, ImmutableList<V>> builder = 361 new ImmutableMap.Builder<>(mapEntries.size()); 362 int size = 0; 363 364 for (Entry<? extends K, ? extends Collection<? extends V>> entry : mapEntries) { 365 K key = entry.getKey(); 366 Collection<? extends V> values = entry.getValue(); 367 ImmutableList<V> list = 368 (valueComparator == null) 369 ? ImmutableList.copyOf(values) 370 : ImmutableList.sortedCopyOf(valueComparator, values); 371 if (!list.isEmpty()) { 372 builder.put(key, list); 373 size += list.size(); 374 } 375 } 376 377 return new ImmutableListMultimap<>(builder.buildOrThrow(), size); 378 } 379 380 ImmutableListMultimap(ImmutableMap<K, ImmutableList<V>> map, int size) { 381 super(map, size); 382 } 383 384 // views 385 386 /** 387 * Returns an immutable list of the values for the given key. If no mappings in the multimap have 388 * the provided key, an empty immutable list is returned. The values are in the same order as the 389 * parameters used to build this multimap. 390 */ 391 @Override 392 public ImmutableList<V> get(K key) { 393 // This cast is safe as its type is known in constructor. 394 ImmutableList<V> list = (ImmutableList<V>) map.get(key); 395 return (list == null) ? ImmutableList.<V>of() : list; 396 } 397 398 @LazyInit @RetainedWith @CheckForNull private transient ImmutableListMultimap<V, K> inverse; 399 400 /** 401 * {@inheritDoc} 402 * 403 * <p>Because an inverse of a list multimap can contain multiple pairs with the same key and 404 * value, this method returns an {@code ImmutableListMultimap} rather than the {@code 405 * ImmutableMultimap} specified in the {@code ImmutableMultimap} class. 406 * 407 * @since 11.0 408 */ 409 @Override 410 public ImmutableListMultimap<V, K> inverse() { 411 ImmutableListMultimap<V, K> result = inverse; 412 return (result == null) ? (inverse = invert()) : result; 413 } 414 415 private ImmutableListMultimap<V, K> invert() { 416 Builder<V, K> builder = builder(); 417 for (Entry<K, V> entry : entries()) { 418 builder.put(entry.getValue(), entry.getKey()); 419 } 420 ImmutableListMultimap<V, K> invertedMultimap = builder.build(); 421 invertedMultimap.inverse = this; 422 return invertedMultimap; 423 } 424 425 /** 426 * Guaranteed to throw an exception and leave the multimap unmodified. 427 * 428 * @throws UnsupportedOperationException always 429 * @deprecated Unsupported operation. 430 */ 431 @CanIgnoreReturnValue 432 @Deprecated 433 @Override 434 @DoNotCall("Always throws UnsupportedOperationException") 435 public final ImmutableList<V> removeAll(@CheckForNull Object key) { 436 throw new UnsupportedOperationException(); 437 } 438 439 /** 440 * Guaranteed to throw an exception and leave the multimap unmodified. 441 * 442 * @throws UnsupportedOperationException always 443 * @deprecated Unsupported operation. 444 */ 445 @CanIgnoreReturnValue 446 @Deprecated 447 @Override 448 @DoNotCall("Always throws UnsupportedOperationException") 449 public final ImmutableList<V> replaceValues(K key, Iterable<? extends V> values) { 450 throw new UnsupportedOperationException(); 451 } 452 453 /** 454 * @serialData number of distinct keys, and then for each distinct key: the key, the number of 455 * values for that key, and the key's values 456 */ 457 @GwtIncompatible // java.io.ObjectOutputStream 458 @J2ktIncompatible 459 private void writeObject(ObjectOutputStream stream) throws IOException { 460 stream.defaultWriteObject(); 461 Serialization.writeMultimap(this, stream); 462 } 463 464 @GwtIncompatible // java.io.ObjectInputStream 465 @J2ktIncompatible 466 private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException { 467 stream.defaultReadObject(); 468 int keyCount = stream.readInt(); 469 if (keyCount < 0) { 470 throw new InvalidObjectException("Invalid key count " + keyCount); 471 } 472 ImmutableMap.Builder<Object, ImmutableList<Object>> builder = 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 ImmutableList.Builder<Object> valuesBuilder = ImmutableList.builder(); 483 for (int j = 0; j < valueCount; j++) { 484 valuesBuilder.add(stream.readObject()); 485 } 486 builder.put(key, valuesBuilder.build()); 487 tmpSize += valueCount; 488 } 489 490 ImmutableMap<Object, ImmutableList<Object>> tmpMap; 491 try { 492 tmpMap = builder.buildOrThrow(); 493 } catch (IllegalArgumentException e) { 494 throw (InvalidObjectException) new InvalidObjectException(e.getMessage()).initCause(e); 495 } 496 497 FieldSettersHolder.MAP_FIELD_SETTER.set(this, tmpMap); 498 FieldSettersHolder.SIZE_FIELD_SETTER.set(this, tmpSize); 499 } 500 501 @GwtIncompatible // Not needed in emulated source 502 @J2ktIncompatible 503 private static final long serialVersionUID = 0; 504}