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; 018 019 020import com.google.common.annotations.Beta; 021import com.google.common.annotations.GwtCompatible; 022import com.google.common.annotations.GwtIncompatible; 023import com.google.errorprone.annotations.CanIgnoreReturnValue; 024import com.google.errorprone.annotations.DoNotCall; 025import com.google.errorprone.annotations.concurrent.LazyInit; 026import com.google.j2objc.annotations.RetainedWith; 027import java.io.IOException; 028import java.io.InvalidObjectException; 029import java.io.ObjectInputStream; 030import java.io.ObjectOutputStream; 031import java.util.Collection; 032import java.util.Comparator; 033import java.util.Map; 034import java.util.Map.Entry; 035import java.util.function.Function; 036import java.util.stream.Collector; 037import java.util.stream.Stream; 038import javax.annotation.CheckForNull; 039import org.checkerframework.checker.nullness.qual.Nullable; 040 041/** 042 * A {@link ListMultimap} whose contents will never change, with many other important properties 043 * detailed at {@link ImmutableCollection}. 044 * 045 * <p>See the Guava User Guide article on <a href= 046 * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained">immutable collections</a>. 047 * 048 * @author Jared Levy 049 * @since 2.0 050 */ 051@GwtCompatible(serializable = true, emulated = true) 052@ElementTypesAreNonnullByDefault 053public class ImmutableListMultimap<K, V> extends ImmutableMultimap<K, V> 054 implements ListMultimap<K, V> { 055 /** 056 * Returns a {@link Collector} that accumulates elements into an {@code ImmutableListMultimap} 057 * whose keys and values are the result of applying the provided mapping functions to the input 058 * elements. 059 * 060 * <p>For streams with defined encounter order (as defined in the Ordering section of the {@link 061 * java.util.stream} Javadoc), that order is preserved, but entries are <a 062 * href="ImmutableMultimap.html#iteration">grouped by key</a>. 063 * 064 * <p>Example: 065 * 066 * <pre>{@code 067 * static final Multimap<Character, String> FIRST_LETTER_MULTIMAP = 068 * Stream.of("banana", "apple", "carrot", "asparagus", "cherry") 069 * .collect(toImmutableListMultimap(str -> str.charAt(0), str -> str.substring(1))); 070 * 071 * // is equivalent to 072 * 073 * static final Multimap<Character, String> FIRST_LETTER_MULTIMAP = 074 * new ImmutableListMultimap.Builder<Character, String>() 075 * .put('b', "anana") 076 * .putAll('a', "pple", "sparagus") 077 * .putAll('c', "arrot", "herry") 078 * .build(); 079 * }</pre> 080 * 081 * @since 21.0 082 */ 083 public static <T extends @Nullable Object, K, V> 084 Collector<T, ?, ImmutableListMultimap<K, V>> toImmutableListMultimap( 085 Function<? super T, ? extends K> keyFunction, 086 Function<? super T, ? extends V> valueFunction) { 087 return CollectCollectors.toImmutableListMultimap(keyFunction, valueFunction); 088 } 089 090 /** 091 * Returns a {@code Collector} accumulating entries into an {@code ImmutableListMultimap}. Each 092 * input element is mapped to a key and a stream of values, each of which are put into the 093 * resulting {@code Multimap}, in the encounter order of the stream and the encounter order of the 094 * streams of values. 095 * 096 * <p>Example: 097 * 098 * <pre>{@code 099 * static final ImmutableListMultimap<Character, Character> FIRST_LETTER_MULTIMAP = 100 * Stream.of("banana", "apple", "carrot", "asparagus", "cherry") 101 * .collect( 102 * flatteningToImmutableListMultimap( 103 * str -> str.charAt(0), 104 * str -> str.substring(1).chars().mapToObj(c -> (char) c)); 105 * 106 * // is equivalent to 107 * 108 * static final ImmutableListMultimap<Character, Character> FIRST_LETTER_MULTIMAP = 109 * ImmutableListMultimap.<Character, Character>builder() 110 * .putAll('b', Arrays.asList('a', 'n', 'a', 'n', 'a')) 111 * .putAll('a', Arrays.asList('p', 'p', 'l', 'e')) 112 * .putAll('c', Arrays.asList('a', 'r', 'r', 'o', 't')) 113 * .putAll('a', Arrays.asList('s', 'p', 'a', 'r', 'a', 'g', 'u', 's')) 114 * .putAll('c', Arrays.asList('h', 'e', 'r', 'r', 'y')) 115 * .build(); 116 * } 117 * }</pre> 118 * 119 * @since 21.0 120 */ 121 public static <T extends @Nullable Object, K, V> 122 Collector<T, ?, ImmutableListMultimap<K, V>> flatteningToImmutableListMultimap( 123 Function<? super T, ? extends K> keyFunction, 124 Function<? super T, ? extends Stream<? extends V>> valuesFunction) { 125 return CollectCollectors.flatteningToImmutableListMultimap(keyFunction, valuesFunction); 126 } 127 128 /** 129 * Returns the empty multimap. 130 * 131 * <p><b>Performance note:</b> the instance returned is a singleton. 132 */ 133 // Casting is safe because the multimap will never hold any elements. 134 @SuppressWarnings("unchecked") 135 public static <K, V> ImmutableListMultimap<K, V> of() { 136 return (ImmutableListMultimap<K, V>) EmptyImmutableListMultimap.INSTANCE; 137 } 138 139 /** Returns an immutable multimap containing a single entry. */ 140 public static <K, V> ImmutableListMultimap<K, V> of(K k1, V v1) { 141 ImmutableListMultimap.Builder<K, V> builder = ImmutableListMultimap.builder(); 142 builder.put(k1, v1); 143 return builder.build(); 144 } 145 146 /** Returns an immutable multimap containing the given entries, in order. */ 147 public static <K, V> ImmutableListMultimap<K, V> of(K k1, V v1, K k2, V v2) { 148 ImmutableListMultimap.Builder<K, V> builder = ImmutableListMultimap.builder(); 149 builder.put(k1, v1); 150 builder.put(k2, v2); 151 return builder.build(); 152 } 153 154 /** Returns an immutable multimap containing the given entries, in order. */ 155 public static <K, V> ImmutableListMultimap<K, V> of(K k1, V v1, K k2, V v2, K k3, V v3) { 156 ImmutableListMultimap.Builder<K, V> builder = ImmutableListMultimap.builder(); 157 builder.put(k1, v1); 158 builder.put(k2, v2); 159 builder.put(k3, v3); 160 return builder.build(); 161 } 162 163 /** Returns an immutable multimap containing the given entries, in order. */ 164 public static <K, V> ImmutableListMultimap<K, V> of( 165 K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4) { 166 ImmutableListMultimap.Builder<K, V> builder = ImmutableListMultimap.builder(); 167 builder.put(k1, v1); 168 builder.put(k2, v2); 169 builder.put(k3, v3); 170 builder.put(k4, v4); 171 return builder.build(); 172 } 173 174 /** Returns an immutable multimap containing the given entries, in order. */ 175 public static <K, V> ImmutableListMultimap<K, V> of( 176 K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5) { 177 ImmutableListMultimap.Builder<K, V> builder = ImmutableListMultimap.builder(); 178 builder.put(k1, v1); 179 builder.put(k2, v2); 180 builder.put(k3, v3); 181 builder.put(k4, v4); 182 builder.put(k5, v5); 183 return builder.build(); 184 } 185 186 // looking for of() with > 5 entries? Use the builder instead. 187 188 /** 189 * Returns a new builder. The generated builder is equivalent to the builder created by the {@link 190 * Builder} constructor. 191 */ 192 public static <K, V> Builder<K, V> builder() { 193 return new Builder<>(); 194 } 195 196 /** 197 * A builder for creating immutable {@code ListMultimap} instances, especially {@code public 198 * static final} multimaps ("constant multimaps"). Example: 199 * 200 * <pre>{@code 201 * static final Multimap<String, Integer> STRING_TO_INTEGER_MULTIMAP = 202 * new ImmutableListMultimap.Builder<String, Integer>() 203 * .put("one", 1) 204 * .putAll("several", 1, 2, 3) 205 * .putAll("many", 1, 2, 3, 4, 5) 206 * .build(); 207 * }</pre> 208 * 209 * <p>Builder instances can be reused; it is safe to call {@link #build} multiple times to build 210 * multiple multimaps in series. Each multimap contains the key-value mappings in the previously 211 * created multimaps. 212 * 213 * @since 2.0 214 */ 215 public static final class Builder<K, V> extends ImmutableMultimap.Builder<K, V> { 216 /** 217 * Creates a new builder. The returned builder is equivalent to the builder generated by {@link 218 * ImmutableListMultimap#builder}. 219 */ 220 public Builder() {} 221 222 @CanIgnoreReturnValue 223 @Override 224 public Builder<K, V> put(K key, V value) { 225 super.put(key, value); 226 return this; 227 } 228 229 /** 230 * {@inheritDoc} 231 * 232 * @since 11.0 233 */ 234 @CanIgnoreReturnValue 235 @Override 236 public Builder<K, V> put(Entry<? extends K, ? extends V> entry) { 237 super.put(entry); 238 return this; 239 } 240 241 /** 242 * {@inheritDoc} 243 * 244 * @since 19.0 245 */ 246 @CanIgnoreReturnValue 247 @Beta 248 @Override 249 public Builder<K, V> putAll(Iterable<? extends Entry<? extends K, ? extends V>> entries) { 250 super.putAll(entries); 251 return this; 252 } 253 254 @CanIgnoreReturnValue 255 @Override 256 public Builder<K, V> putAll(K key, Iterable<? extends V> values) { 257 super.putAll(key, values); 258 return this; 259 } 260 261 @CanIgnoreReturnValue 262 @Override 263 public Builder<K, V> putAll(K key, V... values) { 264 super.putAll(key, values); 265 return this; 266 } 267 268 @CanIgnoreReturnValue 269 @Override 270 public Builder<K, V> putAll(Multimap<? extends K, ? extends V> multimap) { 271 super.putAll(multimap); 272 return this; 273 } 274 275 @CanIgnoreReturnValue 276 @Override 277 Builder<K, V> combine(ImmutableMultimap.Builder<K, V> other) { 278 super.combine(other); 279 return this; 280 } 281 282 /** 283 * {@inheritDoc} 284 * 285 * @since 8.0 286 */ 287 @CanIgnoreReturnValue 288 @Override 289 public Builder<K, V> orderKeysBy(Comparator<? super K> keyComparator) { 290 super.orderKeysBy(keyComparator); 291 return this; 292 } 293 294 /** 295 * {@inheritDoc} 296 * 297 * @since 8.0 298 */ 299 @CanIgnoreReturnValue 300 @Override 301 public Builder<K, V> orderValuesBy(Comparator<? super V> valueComparator) { 302 super.orderValuesBy(valueComparator); 303 return this; 304 } 305 306 /** Returns a newly-created immutable list multimap. */ 307 @Override 308 public ImmutableListMultimap<K, V> build() { 309 return (ImmutableListMultimap<K, V>) super.build(); 310 } 311 } 312 313 /** 314 * Returns an immutable multimap containing the same mappings as {@code multimap}. The generated 315 * multimap's key and value orderings correspond to the iteration ordering of the {@code 316 * multimap.asMap()} view. 317 * 318 * <p>Despite the method name, this method attempts to avoid actually copying the data when it is 319 * safe to do so. The exact circumstances under which a copy will or will not be performed are 320 * undocumented and subject to change. 321 * 322 * @throws NullPointerException if any key or value in {@code multimap} is null 323 */ 324 public static <K, V> ImmutableListMultimap<K, V> copyOf( 325 Multimap<? extends K, ? extends V> multimap) { 326 if (multimap.isEmpty()) { 327 return of(); 328 } 329 330 // TODO(lowasser): copy ImmutableSetMultimap by using asList() on the sets 331 if (multimap instanceof ImmutableListMultimap) { 332 @SuppressWarnings("unchecked") // safe since multimap is not writable 333 ImmutableListMultimap<K, V> kvMultimap = (ImmutableListMultimap<K, V>) multimap; 334 if (!kvMultimap.isPartialView()) { 335 return kvMultimap; 336 } 337 } 338 339 return fromMapEntries(multimap.asMap().entrySet(), null); 340 } 341 342 /** 343 * Returns an immutable multimap containing the specified entries. The returned multimap iterates 344 * over keys in the order they were first encountered in the input, and the values for each key 345 * are iterated in the order they were encountered. 346 * 347 * @throws NullPointerException if any key, value, or entry is null 348 * @since 19.0 349 */ 350 @Beta 351 public static <K, V> ImmutableListMultimap<K, V> copyOf( 352 Iterable<? extends Entry<? extends K, ? extends V>> entries) { 353 return new Builder<K, V>().putAll(entries).build(); 354 } 355 356 /** Creates an ImmutableListMultimap from an asMap.entrySet. */ 357 static <K, V> ImmutableListMultimap<K, V> fromMapEntries( 358 Collection<? extends Map.Entry<? extends K, ? extends Collection<? extends V>>> mapEntries, 359 @Nullable Comparator<? super V> valueComparator) { 360 if (mapEntries.isEmpty()) { 361 return of(); 362 } 363 ImmutableMap.Builder<K, ImmutableList<V>> builder = 364 new ImmutableMap.Builder<>(mapEntries.size()); 365 int size = 0; 366 367 for (Entry<? extends K, ? extends Collection<? extends V>> entry : mapEntries) { 368 K key = entry.getKey(); 369 Collection<? extends V> values = entry.getValue(); 370 ImmutableList<V> list = 371 (valueComparator == null) 372 ? ImmutableList.copyOf(values) 373 : ImmutableList.sortedCopyOf(valueComparator, values); 374 if (!list.isEmpty()) { 375 builder.put(key, list); 376 size += list.size(); 377 } 378 } 379 380 return new ImmutableListMultimap<>(builder.buildOrThrow(), size); 381 } 382 383 ImmutableListMultimap(ImmutableMap<K, ImmutableList<V>> map, int size) { 384 super(map, size); 385 } 386 387 // views 388 389 /** 390 * Returns an immutable list of the values for the given key. If no mappings in the multimap have 391 * the provided key, an empty immutable list is returned. The values are in the same order as the 392 * parameters used to build this multimap. 393 */ 394 @Override 395 public ImmutableList<V> get(K key) { 396 // This cast is safe as its type is known in constructor. 397 ImmutableList<V> list = (ImmutableList<V>) map.get(key); 398 return (list == null) ? ImmutableList.<V>of() : list; 399 } 400 401 @LazyInit @RetainedWith @CheckForNull private transient ImmutableListMultimap<V, K> inverse; 402 403 /** 404 * {@inheritDoc} 405 * 406 * <p>Because an inverse of a list multimap can contain multiple pairs with the same key and 407 * value, this method returns an {@code ImmutableListMultimap} rather than the {@code 408 * ImmutableMultimap} specified in the {@code ImmutableMultimap} class. 409 * 410 * @since 11.0 411 */ 412 @Override 413 public ImmutableListMultimap<V, K> inverse() { 414 ImmutableListMultimap<V, K> result = inverse; 415 return (result == null) ? (inverse = invert()) : result; 416 } 417 418 private ImmutableListMultimap<V, K> invert() { 419 Builder<V, K> builder = builder(); 420 for (Entry<K, V> entry : entries()) { 421 builder.put(entry.getValue(), entry.getKey()); 422 } 423 ImmutableListMultimap<V, K> invertedMultimap = builder.build(); 424 invertedMultimap.inverse = this; 425 return invertedMultimap; 426 } 427 428 /** 429 * Guaranteed to throw an exception and leave the multimap unmodified. 430 * 431 * @throws UnsupportedOperationException always 432 * @deprecated Unsupported operation. 433 */ 434 @CanIgnoreReturnValue 435 @Deprecated 436 @Override 437 @DoNotCall("Always throws UnsupportedOperationException") 438 public final ImmutableList<V> removeAll(@CheckForNull Object key) { 439 throw new UnsupportedOperationException(); 440 } 441 442 /** 443 * Guaranteed to throw an exception and leave the multimap unmodified. 444 * 445 * @throws UnsupportedOperationException always 446 * @deprecated Unsupported operation. 447 */ 448 @CanIgnoreReturnValue 449 @Deprecated 450 @Override 451 @DoNotCall("Always throws UnsupportedOperationException") 452 public final ImmutableList<V> replaceValues(K key, Iterable<? extends V> values) { 453 throw new UnsupportedOperationException(); 454 } 455 456 /** 457 * @serialData number of distinct keys, and then for each distinct key: the key, the number of 458 * values for that key, and the key's values 459 */ 460 @GwtIncompatible // java.io.ObjectOutputStream 461 private void writeObject(ObjectOutputStream stream) throws IOException { 462 stream.defaultWriteObject(); 463 Serialization.writeMultimap(this, stream); 464 } 465 466 @GwtIncompatible // java.io.ObjectInputStream 467 private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException { 468 stream.defaultReadObject(); 469 int keyCount = stream.readInt(); 470 if (keyCount < 0) { 471 throw new InvalidObjectException("Invalid key count " + keyCount); 472 } 473 ImmutableMap.Builder<Object, ImmutableList<Object>> builder = ImmutableMap.builder(); 474 int tmpSize = 0; 475 476 for (int i = 0; i < keyCount; i++) { 477 Object key = stream.readObject(); 478 int valueCount = stream.readInt(); 479 if (valueCount <= 0) { 480 throw new InvalidObjectException("Invalid value count " + valueCount); 481 } 482 483 ImmutableList.Builder<Object> valuesBuilder = ImmutableList.builder(); 484 for (int j = 0; j < valueCount; j++) { 485 valuesBuilder.add(stream.readObject()); 486 } 487 builder.put(key, valuesBuilder.build()); 488 tmpSize += valueCount; 489 } 490 491 ImmutableMap<Object, ImmutableList<Object>> tmpMap; 492 try { 493 tmpMap = builder.buildOrThrow(); 494 } catch (IllegalArgumentException e) { 495 throw (InvalidObjectException) new InvalidObjectException(e.getMessage()).initCause(e); 496 } 497 498 FieldSettersHolder.MAP_FIELD_SETTER.set(this, tmpMap); 499 FieldSettersHolder.SIZE_FIELD_SETTER.set(this, tmpSize); 500 } 501 502 @GwtIncompatible // Not needed in emulated source 503 private static final long serialVersionUID = 0; 504}