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.GwtCompatible; 022import com.google.common.annotations.GwtIncompatible; 023import com.google.common.base.Function; 024 025import java.io.IOException; 026import java.io.InvalidObjectException; 027import java.io.ObjectInputStream; 028import java.io.ObjectOutputStream; 029import java.util.Arrays; 030import java.util.Collection; 031import java.util.Collections; 032import java.util.Comparator; 033import java.util.LinkedHashMap; 034import java.util.List; 035import java.util.Map; 036import java.util.Map.Entry; 037 038import javax.annotation.Nullable; 039 040/** 041 * An immutable {@link SetMultimap} with reliable user-specified key and value 042 * iteration order. Does not permit null keys or values. 043 * 044 * <p>Unlike {@link Multimaps#unmodifiableSetMultimap(SetMultimap)}, which is 045 * a <i>view</i> of a separate multimap which can still change, an instance of 046 * {@code ImmutableSetMultimap} contains its own data and will <i>never</i> 047 * change. {@code ImmutableSetMultimap} is convenient for 048 * {@code public static final} multimaps ("constant multimaps") and also lets 049 * you easily make a "defensive copy" of a multimap provided to your class by 050 * a caller. 051 * 052 * <p><b>Note:</b> Although this class is not final, it cannot be subclassed as 053 * it has no public or protected constructors. Thus, instances of this class 054 * are guaranteed to be immutable. 055 * 056 * <p>See the Guava User Guide article on <a href= 057 * "http://code.google.com/p/guava-libraries/wiki/ImmutableCollectionsExplained"> 058 * immutable collections</a>. 059 * 060 * @author Mike Ward 061 * @since 2.0 (imported from Google Collections Library) 062 */ 063@GwtCompatible(serializable = true, emulated = true) 064public class ImmutableSetMultimap<K, V> 065 extends ImmutableMultimap<K, V> 066 implements SetMultimap<K, V> { 067 068 /** Returns the empty multimap. */ 069 // Casting is safe because the multimap will never hold any elements. 070 @SuppressWarnings("unchecked") 071 public static <K, V> ImmutableSetMultimap<K, V> of() { 072 return (ImmutableSetMultimap<K, V>) EmptyImmutableSetMultimap.INSTANCE; 073 } 074 075 /** 076 * Returns an immutable multimap containing a single entry. 077 */ 078 public static <K, V> ImmutableSetMultimap<K, V> of(K k1, V v1) { 079 ImmutableSetMultimap.Builder<K, V> builder = ImmutableSetMultimap.builder(); 080 builder.put(k1, v1); 081 return builder.build(); 082 } 083 084 /** 085 * Returns an immutable multimap containing the given entries, in order. 086 * Repeated occurrences of an entry (according to {@link Object#equals}) after 087 * the first are ignored. 088 */ 089 public static <K, V> ImmutableSetMultimap<K, V> of(K k1, V v1, K k2, V v2) { 090 ImmutableSetMultimap.Builder<K, V> builder = ImmutableSetMultimap.builder(); 091 builder.put(k1, v1); 092 builder.put(k2, v2); 093 return builder.build(); 094 } 095 096 /** 097 * Returns an immutable multimap containing the given entries, in order. 098 * Repeated occurrences of an entry (according to {@link Object#equals}) after 099 * the first are ignored. 100 */ 101 public static <K, V> ImmutableSetMultimap<K, V> of( 102 K k1, V v1, K k2, V v2, K k3, V v3) { 103 ImmutableSetMultimap.Builder<K, V> builder = ImmutableSetMultimap.builder(); 104 builder.put(k1, v1); 105 builder.put(k2, v2); 106 builder.put(k3, v3); 107 return builder.build(); 108 } 109 110 /** 111 * Returns an immutable multimap containing the given entries, in order. 112 * Repeated occurrences of an entry (according to {@link Object#equals}) after 113 * the first are ignored. 114 */ 115 public static <K, V> ImmutableSetMultimap<K, V> of( 116 K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4) { 117 ImmutableSetMultimap.Builder<K, V> builder = ImmutableSetMultimap.builder(); 118 builder.put(k1, v1); 119 builder.put(k2, v2); 120 builder.put(k3, v3); 121 builder.put(k4, v4); 122 return builder.build(); 123 } 124 125 /** 126 * Returns an immutable multimap containing the given entries, in order. 127 * Repeated occurrences of an entry (according to {@link Object#equals}) after 128 * the first are ignored. 129 */ 130 public static <K, V> ImmutableSetMultimap<K, V> of( 131 K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5) { 132 ImmutableSetMultimap.Builder<K, V> builder = ImmutableSetMultimap.builder(); 133 builder.put(k1, v1); 134 builder.put(k2, v2); 135 builder.put(k3, v3); 136 builder.put(k4, v4); 137 builder.put(k5, v5); 138 return builder.build(); 139 } 140 141 // looking for of() with > 5 entries? Use the builder instead. 142 143 /** 144 * Returns a new {@link Builder}. 145 */ 146 public static <K, V> Builder<K, V> builder() { 147 return new Builder<K, V>(); 148 } 149 150 /** 151 * Multimap for {@link ImmutableSetMultimap.Builder} that maintains key 152 * and value orderings and performs better than {@link LinkedHashMultimap}. 153 */ 154 private static class BuilderMultimap<K, V> extends AbstractMapBasedMultimap<K, V> { 155 BuilderMultimap() { 156 super(new LinkedHashMap<K, Collection<V>>()); 157 } 158 @Override Collection<V> createCollection() { 159 return Sets.newLinkedHashSet(); 160 } 161 private static final long serialVersionUID = 0; 162 } 163 164 /** 165 * A builder for creating immutable {@code SetMultimap} instances, especially 166 * {@code public static final} multimaps ("constant multimaps"). Example: 167 * <pre> {@code 168 * 169 * static final Multimap<String, Integer> STRING_TO_INTEGER_MULTIMAP = 170 * new ImmutableSetMultimap.Builder<String, Integer>() 171 * .put("one", 1) 172 * .putAll("several", 1, 2, 3) 173 * .putAll("many", 1, 2, 3, 4, 5) 174 * .build();}</pre> 175 * 176 * Builder instances can be reused; it is safe to call {@link #build} multiple 177 * times to build multiple multimaps in series. Each multimap contains the 178 * key-value mappings in the previously created multimaps. 179 * 180 * @since 2.0 (imported from Google Collections Library) 181 */ 182 public static final class Builder<K, V> 183 extends ImmutableMultimap.Builder<K, V> { 184 /** 185 * Creates a new builder. The returned builder is equivalent to the builder 186 * generated by {@link ImmutableSetMultimap#builder}. 187 */ 188 public Builder() { 189 builderMultimap = new BuilderMultimap<K, V>(); 190 } 191 192 /** 193 * Adds a key-value mapping to the built multimap if it is not already 194 * present. 195 */ 196 @Override public Builder<K, V> put(K key, V value) { 197 builderMultimap.put(checkNotNull(key), checkNotNull(value)); 198 return this; 199 } 200 201 /** 202 * Adds an entry to the built multimap if it is not already present. 203 * 204 * @since 11.0 205 */ 206 @Override public Builder<K, V> put(Entry<? extends K, ? extends V> entry) { 207 builderMultimap.put( 208 checkNotNull(entry.getKey()), checkNotNull(entry.getValue())); 209 return this; 210 } 211 212 @Override public Builder<K, V> putAll(K key, Iterable<? extends V> values) { 213 Collection<V> collection = builderMultimap.get(checkNotNull(key)); 214 for (V value : values) { 215 collection.add(checkNotNull(value)); 216 } 217 return this; 218 } 219 220 @Override public Builder<K, V> putAll(K key, V... values) { 221 return putAll(key, Arrays.asList(values)); 222 } 223 224 @Override public Builder<K, V> putAll( 225 Multimap<? extends K, ? extends V> multimap) { 226 for (Entry<? extends K, ? extends Collection<? extends V>> entry 227 : multimap.asMap().entrySet()) { 228 putAll(entry.getKey(), entry.getValue()); 229 } 230 return this; 231 } 232 233 /** 234 * {@inheritDoc} 235 * 236 * @since 8.0 237 */ 238 @Override 239 public Builder<K, V> orderKeysBy(Comparator<? super K> keyComparator) { 240 this.keyComparator = checkNotNull(keyComparator); 241 return this; 242 } 243 244 /** 245 * Specifies the ordering of the generated multimap's values for each key. 246 * 247 * <p>If this method is called, the sets returned by the {@code get()} 248 * method of the generated multimap and its {@link Multimap#asMap()} view 249 * are {@link ImmutableSortedSet} instances. However, serialization does not 250 * preserve that property, though it does maintain the key and value 251 * ordering. 252 * 253 * @since 8.0 254 */ 255 // TODO: Make serialization behavior consistent. 256 @Override 257 public Builder<K, V> orderValuesBy(Comparator<? super V> valueComparator) { 258 super.orderValuesBy(valueComparator); 259 return this; 260 } 261 262 /** 263 * Returns a newly-created immutable set multimap. 264 */ 265 @Override public ImmutableSetMultimap<K, V> build() { 266 if (keyComparator != null) { 267 Multimap<K, V> sortedCopy = new BuilderMultimap<K, V>(); 268 List<Map.Entry<K, Collection<V>>> entries = Lists.newArrayList( 269 builderMultimap.asMap().entrySet()); 270 Collections.sort( 271 entries, 272 Ordering.from(keyComparator).onResultOf(new Function<Entry<K, Collection<V>>, K>() { 273 @Override 274 public K apply(Entry<K, Collection<V>> entry) { 275 return entry.getKey(); 276 } 277 })); 278 for (Map.Entry<K, Collection<V>> entry : entries) { 279 sortedCopy.putAll(entry.getKey(), entry.getValue()); 280 } 281 builderMultimap = sortedCopy; 282 } 283 return copyOf(builderMultimap, valueComparator); 284 } 285 } 286 287 /** 288 * Returns an immutable set multimap containing the same mappings as 289 * {@code multimap}. The generated multimap's key and value orderings 290 * correspond to the iteration ordering of the {@code multimap.asMap()} view. 291 * Repeated occurrences of an entry in the multimap after the first are 292 * ignored. 293 * 294 * <p>Despite the method name, this method attempts to avoid actually copying 295 * the data when it is safe to do so. The exact circumstances under which a 296 * copy will or will not be performed are undocumented and subject to change. 297 * 298 * @throws NullPointerException if any key or value in {@code multimap} is 299 * null 300 */ 301 public static <K, V> ImmutableSetMultimap<K, V> copyOf( 302 Multimap<? extends K, ? extends V> multimap) { 303 return copyOf(multimap, null); 304 } 305 306 private static <K, V> ImmutableSetMultimap<K, V> copyOf( 307 Multimap<? extends K, ? extends V> multimap, 308 Comparator<? super V> valueComparator) { 309 checkNotNull(multimap); // eager for GWT 310 if (multimap.isEmpty() && valueComparator == null) { 311 return of(); 312 } 313 314 if (multimap instanceof ImmutableSetMultimap) { 315 @SuppressWarnings("unchecked") // safe since multimap is not writable 316 ImmutableSetMultimap<K, V> kvMultimap 317 = (ImmutableSetMultimap<K, V>) multimap; 318 if (!kvMultimap.isPartialView()) { 319 return kvMultimap; 320 } 321 } 322 323 ImmutableMap.Builder<K, ImmutableSet<V>> builder = ImmutableMap.builder(); 324 int size = 0; 325 326 for (Entry<? extends K, ? extends Collection<? extends V>> entry 327 : multimap.asMap().entrySet()) { 328 K key = entry.getKey(); 329 Collection<? extends V> values = entry.getValue(); 330 ImmutableSet<V> set = (valueComparator == null) 331 ? ImmutableSet.copyOf(values) 332 : ImmutableSortedSet.copyOf(valueComparator, values); 333 if (!set.isEmpty()) { 334 builder.put(key, set); 335 size += set.size(); 336 } 337 } 338 339 return new ImmutableSetMultimap<K, V>( 340 builder.build(), size, valueComparator); 341 } 342 343 // Returned by get() when values are sorted and a missing key is provided. 344 private final transient ImmutableSortedSet<V> emptySet; 345 346 ImmutableSetMultimap(ImmutableMap<K, ImmutableSet<V>> map, int size, 347 @Nullable Comparator<? super V> valueComparator) { 348 super(map, size); 349 this.emptySet = (valueComparator == null) 350 ? null : ImmutableSortedSet.<V>emptySet(valueComparator); 351 } 352 353 // views 354 355 /** 356 * Returns an immutable set of the values for the given key. If no mappings 357 * in the multimap have the provided key, an empty immutable set is returned. 358 * The values are in the same order as the parameters used to build this 359 * multimap. 360 */ 361 @Override public ImmutableSet<V> get(@Nullable K key) { 362 // This cast is safe as its type is known in constructor. 363 ImmutableSet<V> set = (ImmutableSet<V>) map.get(key); 364 if (set != null) { 365 return set; 366 } else if (emptySet != null) { 367 return emptySet; 368 } else { 369 return ImmutableSet.<V>of(); 370 } 371 } 372 373 private transient ImmutableSetMultimap<V, K> inverse; 374 375 /** 376 * {@inheritDoc} 377 * 378 * <p>Because an inverse of a set multimap cannot contain multiple pairs with 379 * the same key and value, this method returns an {@code ImmutableSetMultimap} 380 * rather than the {@code ImmutableMultimap} specified in the {@code 381 * ImmutableMultimap} class. 382 * 383 * @since 11.0 384 */ 385 public ImmutableSetMultimap<V, K> inverse() { 386 ImmutableSetMultimap<V, K> result = inverse; 387 return (result == null) ? (inverse = invert()) : result; 388 } 389 390 private ImmutableSetMultimap<V, K> invert() { 391 Builder<V, K> builder = builder(); 392 for (Entry<K, V> entry : entries()) { 393 builder.put(entry.getValue(), entry.getKey()); 394 } 395 ImmutableSetMultimap<V, K> invertedMultimap = builder.build(); 396 invertedMultimap.inverse = this; 397 return invertedMultimap; 398 } 399 400 /** 401 * Guaranteed to throw an exception and leave the multimap unmodified. 402 * 403 * @throws UnsupportedOperationException always 404 * @deprecated Unsupported operation. 405 */ 406 @Deprecated @Override public ImmutableSet<V> removeAll(Object key) { 407 throw new UnsupportedOperationException(); 408 } 409 410 /** 411 * Guaranteed to throw an exception and leave the multimap unmodified. 412 * 413 * @throws UnsupportedOperationException always 414 * @deprecated Unsupported operation. 415 */ 416 @Deprecated @Override public ImmutableSet<V> replaceValues( 417 K key, Iterable<? extends V> values) { 418 throw new UnsupportedOperationException(); 419 } 420 421 private transient ImmutableSet<Entry<K, V>> entries; 422 423 /** 424 * Returns an immutable collection of all key-value pairs in the multimap. 425 * Its iterator traverses the values for the first key, the values for the 426 * second key, and so on. 427 */ 428 // TODO(kevinb): Fix this so that two copies of the entries are not created. 429 @Override public ImmutableSet<Entry<K, V>> entries() { 430 ImmutableSet<Entry<K, V>> result = entries; 431 return (result == null) 432 ? (entries = ImmutableSet.copyOf(super.entries())) 433 : result; 434 } 435 436 /** 437 * @serialData number of distinct keys, and then for each distinct key: the 438 * key, the number of values for that key, and the key's values 439 */ 440 @GwtIncompatible("java.io.ObjectOutputStream") 441 private void writeObject(ObjectOutputStream stream) throws IOException { 442 stream.defaultWriteObject(); 443 Serialization.writeMultimap(this, stream); 444 } 445 446 @GwtIncompatible("java.io.ObjectInputStream") 447 private void readObject(ObjectInputStream stream) 448 throws IOException, ClassNotFoundException { 449 stream.defaultReadObject(); 450 int keyCount = stream.readInt(); 451 if (keyCount < 0) { 452 throw new InvalidObjectException("Invalid key count " + keyCount); 453 } 454 ImmutableMap.Builder<Object, ImmutableSet<Object>> builder 455 = ImmutableMap.builder(); 456 int tmpSize = 0; 457 458 for (int i = 0; i < keyCount; i++) { 459 Object key = stream.readObject(); 460 int valueCount = stream.readInt(); 461 if (valueCount <= 0) { 462 throw new InvalidObjectException("Invalid value count " + valueCount); 463 } 464 465 Object[] array = new Object[valueCount]; 466 for (int j = 0; j < valueCount; j++) { 467 array[j] = stream.readObject(); 468 } 469 ImmutableSet<Object> valueSet = ImmutableSet.copyOf(array); 470 if (valueSet.size() != array.length) { 471 throw new InvalidObjectException( 472 "Duplicate key-value pairs exist for key " + key); 473 } 474 builder.put(key, valueSet); 475 tmpSize += valueCount; 476 } 477 478 ImmutableMap<Object, ImmutableSet<Object>> tmpMap; 479 try { 480 tmpMap = builder.build(); 481 } catch (IllegalArgumentException e) { 482 throw (InvalidObjectException) 483 new InvalidObjectException(e.getMessage()).initCause(e); 484 } 485 486 FieldSettersHolder.MAP_FIELD_SETTER.set(this, tmpMap); 487 FieldSettersHolder.SIZE_FIELD_SETTER.set(this, tmpSize); 488 } 489 490 @GwtIncompatible("not needed in emulated source.") 491 private static final long serialVersionUID = 0; 492}