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
017 package com.google.common.collect;
018
019 import com.google.common.annotations.Beta;
020 import com.google.common.annotations.GwtCompatible;
021 import com.google.common.annotations.GwtIncompatible;
022
023 import java.io.IOException;
024 import java.io.InvalidObjectException;
025 import java.io.ObjectInputStream;
026 import java.io.ObjectOutputStream;
027 import java.util.Collection;
028 import java.util.Comparator;
029 import java.util.Map.Entry;
030
031 import javax.annotation.Nullable;
032
033 /**
034 * An immutable {@link ListMultimap} with reliable user-specified key and value
035 * iteration order. Does not permit null keys or values.
036 *
037 * <p>Unlike {@link Multimaps#unmodifiableListMultimap(ListMultimap)}, which is
038 * a <i>view</i> of a separate multimap which can still change, an instance of
039 * {@code ImmutableListMultimap} contains its own data and will <i>never</i>
040 * change. {@code ImmutableListMultimap} is convenient for
041 * {@code public static final} multimaps ("constant multimaps") and also lets
042 * you easily make a "defensive copy" of a multimap provided to your class by
043 * a caller.
044 *
045 * <p><b>Note:</b> Although this class is not final, it cannot be subclassed as
046 * it has no public or protected constructors. Thus, instances of this class
047 * are guaranteed to be immutable.
048 *
049 * <p>See the Guava User Guide article on <a href=
050 * "http://code.google.com/p/guava-libraries/wiki/ImmutableCollectionsExplained">
051 * immutable collections</a>.
052 *
053 * @author Jared Levy
054 * @since 2.0 (imported from Google Collections Library)
055 */
056 @GwtCompatible(serializable = true, emulated = true)
057 public class ImmutableListMultimap<K, V>
058 extends ImmutableMultimap<K, V>
059 implements ListMultimap<K, V> {
060
061 /** Returns the empty multimap. */
062 // Casting is safe because the multimap will never hold any elements.
063 @SuppressWarnings("unchecked")
064 public static <K, V> ImmutableListMultimap<K, V> of() {
065 return (ImmutableListMultimap<K, V>) EmptyImmutableListMultimap.INSTANCE;
066 }
067
068 /**
069 * Returns an immutable multimap containing a single entry.
070 */
071 public static <K, V> ImmutableListMultimap<K, V> of(K k1, V v1) {
072 ImmutableListMultimap.Builder<K, V> builder
073 = ImmutableListMultimap.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 */
081 public static <K, V> ImmutableListMultimap<K, V> of(K k1, V v1, K k2, V v2) {
082 ImmutableListMultimap.Builder<K, V> builder
083 = ImmutableListMultimap.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.
091 */
092 public static <K, V> ImmutableListMultimap<K, V> of(
093 K k1, V v1, K k2, V v2, K k3, V v3) {
094 ImmutableListMultimap.Builder<K, V> builder
095 = ImmutableListMultimap.builder();
096 builder.put(k1, v1);
097 builder.put(k2, v2);
098 builder.put(k3, v3);
099 return builder.build();
100 }
101
102 /**
103 * Returns an immutable multimap containing the given entries, in order.
104 */
105 public static <K, V> ImmutableListMultimap<K, V> of(
106 K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4) {
107 ImmutableListMultimap.Builder<K, V> builder
108 = ImmutableListMultimap.builder();
109 builder.put(k1, v1);
110 builder.put(k2, v2);
111 builder.put(k3, v3);
112 builder.put(k4, v4);
113 return builder.build();
114 }
115
116 /**
117 * Returns an immutable multimap containing the given entries, in order.
118 */
119 public static <K, V> ImmutableListMultimap<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 ImmutableListMultimap.Builder<K, V> builder
122 = ImmutableListMultimap.builder();
123 builder.put(k1, v1);
124 builder.put(k2, v2);
125 builder.put(k3, v3);
126 builder.put(k4, v4);
127 builder.put(k5, v5);
128 return builder.build();
129 }
130
131 // looking for of() with > 5 entries? Use the builder instead.
132
133 /**
134 * Returns a new builder. The generated builder is equivalent to the builder
135 * created by the {@link Builder} constructor.
136 */
137 public static <K, V> Builder<K, V> builder() {
138 return new Builder<K, V>();
139 }
140
141 /**
142 * A builder for creating immutable {@code ListMultimap} instances, especially
143 * {@code public static final} multimaps ("constant multimaps"). Example:
144 * <pre> {@code
145 *
146 * static final Multimap<String, Integer> STRING_TO_INTEGER_MULTIMAP =
147 * new ImmutableListMultimap.Builder<String, Integer>()
148 * .put("one", 1)
149 * .putAll("several", 1, 2, 3)
150 * .putAll("many", 1, 2, 3, 4, 5)
151 * .build();}</pre>
152 *
153 * Builder instances can be reused; it is safe to call {@link #build} multiple
154 * times to build multiple multimaps in series. Each multimap contains the
155 * key-value mappings in the previously created multimaps.
156 *
157 * @since 2.0 (imported from Google Collections Library)
158 */
159 public static final class Builder<K, V>
160 extends ImmutableMultimap.Builder<K, V> {
161 /**
162 * Creates a new builder. The returned builder is equivalent to the builder
163 * generated by {@link ImmutableListMultimap#builder}.
164 */
165 public Builder() {}
166
167
168 @Override
169 public Builder<K, V> put(K key, V value) {
170 super.put(key, value);
171 return this;
172 }
173
174 /**
175 * {@inheritDoc}
176 *
177 * @since 11.0
178 */
179
180 @Override
181 public Builder<K, V> put(
182 Entry<? extends K, ? extends V> entry) {
183 super.put(entry);
184 return this;
185 }
186
187
188 @Override
189 public Builder<K, V> putAll(K key, Iterable<? extends V> values) {
190 super.putAll(key, values);
191 return this;
192 }
193
194
195 @Override
196 public Builder<K, V> putAll(K key, V... values) {
197 super.putAll(key, values);
198 return this;
199 }
200
201
202 @Override
203 public Builder<K, V> putAll(
204 Multimap<? extends K, ? extends V> multimap) {
205 super.putAll(multimap);
206 return this;
207 }
208
209 /**
210 * {@inheritDoc}
211 *
212 * @since 8.0
213 */
214 @Beta @Override
215 public Builder<K, V> orderKeysBy(Comparator<? super K> keyComparator) {
216 super.orderKeysBy(keyComparator);
217 return this;
218 }
219
220 /**
221 * {@inheritDoc}
222 *
223 * @since 8.0
224 */
225 @Beta @Override
226 public Builder<K, V> orderValuesBy(Comparator<? super V> valueComparator) {
227 super.orderValuesBy(valueComparator);
228 return this;
229 }
230
231 /**
232 * Returns a newly-created immutable list multimap.
233 */
234
235 @Override
236 public ImmutableListMultimap<K, V> build() {
237 return (ImmutableListMultimap<K, V>) super.build();
238 }
239 }
240
241 /**
242 * Returns an immutable multimap containing the same mappings as {@code
243 * multimap}. The generated multimap's key and value orderings correspond to
244 * the iteration ordering of the {@code multimap.asMap()} view.
245 *
246 * <p>Despite the method name, this method attempts to avoid actually copying
247 * the data when it is safe to do so. The exact circumstances under which a
248 * copy will or will not be performed are undocumented and subject to change.
249 *
250 * @throws NullPointerException if any key or value in {@code multimap} is
251 * null
252 */
253 public static <K, V> ImmutableListMultimap<K, V> copyOf(
254 Multimap<? extends K, ? extends V> multimap) {
255 if (multimap.isEmpty()) {
256 return of();
257 }
258
259 // TODO(user): copy ImmutableSetMultimap by using asList() on the sets
260 if (multimap instanceof ImmutableListMultimap) {
261 @SuppressWarnings("unchecked") // safe since multimap is not writable
262 ImmutableListMultimap<K, V> kvMultimap
263 = (ImmutableListMultimap<K, V>) multimap;
264 if (!kvMultimap.isPartialView()) {
265 return kvMultimap;
266 }
267 }
268
269 ImmutableMap.Builder<K, ImmutableList<V>> builder = ImmutableMap.builder();
270 int size = 0;
271
272 for (Entry<? extends K, ? extends Collection<? extends V>> entry
273 : multimap.asMap().entrySet()) {
274 ImmutableList<V> list = ImmutableList.copyOf(entry.getValue());
275 if (!list.isEmpty()) {
276 builder.put(entry.getKey(), list);
277 size += list.size();
278 }
279 }
280
281 return new ImmutableListMultimap<K, V>(builder.build(), size);
282 }
283
284 ImmutableListMultimap(ImmutableMap<K, ImmutableList<V>> map, int size) {
285 super(map, size);
286 }
287
288 // views
289
290 /**
291 * Returns an immutable list of the values for the given key. If no mappings
292 * in the multimap have the provided key, an empty immutable list is
293 * returned. The values are in the same order as the parameters used to build
294 * this multimap.
295 */
296
297 @Override
298 public ImmutableList<V> get(@Nullable K key) {
299 // This cast is safe as its type is known in constructor.
300 ImmutableList<V> list = (ImmutableList<V>) map.get(key);
301 return (list == null) ? ImmutableList.<V>of() : list;
302 }
303
304 private transient ImmutableListMultimap<V, K> inverse;
305
306 /**
307 * {@inheritDoc}
308 *
309 * <p>Because an inverse of a list multimap can contain multiple pairs with
310 * the same key and value, this method returns an {@code
311 * ImmutableListMultimap} rather than the {@code ImmutableMultimap} specified
312 * in the {@code ImmutableMultimap} class.
313 *
314 * @since 11
315 */
316
317 @Override
318 @Beta
319 public ImmutableListMultimap<V, K> inverse() {
320 ImmutableListMultimap<V, K> result = inverse;
321 return (result == null) ? (inverse = invert()) : result;
322 }
323
324 private ImmutableListMultimap<V, K> invert() {
325 Builder<V, K> builder = builder();
326 for (Entry<K, V> entry : entries()) {
327 builder.put(entry.getValue(), entry.getKey());
328 }
329 ImmutableListMultimap<V, K> invertedMultimap = builder.build();
330 invertedMultimap.inverse = this;
331 return invertedMultimap;
332 }
333
334 /**
335 * Guaranteed to throw an exception and leave the multimap unmodified.
336 *
337 * @throws UnsupportedOperationException always
338 */
339
340 @Override
341 public ImmutableList<V> removeAll(Object key) {
342 throw new UnsupportedOperationException();
343 }
344
345 /**
346 * Guaranteed to throw an exception and leave the multimap unmodified.
347 *
348 * @throws UnsupportedOperationException always
349 */
350
351 @Override
352 public ImmutableList<V> replaceValues(
353 K key, Iterable<? extends V> values) {
354 throw new UnsupportedOperationException();
355 }
356
357 /**
358 * @serialData number of distinct keys, and then for each distinct key: the
359 * key, the number of values for that key, and the key's values
360 */
361 @GwtIncompatible("java.io.ObjectOutputStream")
362 private void writeObject(ObjectOutputStream stream) throws IOException {
363 stream.defaultWriteObject();
364 Serialization.writeMultimap(this, stream);
365 }
366
367 @GwtIncompatible("java.io.ObjectInputStream")
368 private void readObject(ObjectInputStream stream)
369 throws IOException, ClassNotFoundException {
370 stream.defaultReadObject();
371 int keyCount = stream.readInt();
372 if (keyCount < 0) {
373 throw new InvalidObjectException("Invalid key count " + keyCount);
374 }
375 ImmutableMap.Builder<Object, ImmutableList<Object>> builder
376 = ImmutableMap.builder();
377 int tmpSize = 0;
378
379 for (int i = 0; i < keyCount; i++) {
380 Object key = stream.readObject();
381 int valueCount = stream.readInt();
382 if (valueCount <= 0) {
383 throw new InvalidObjectException("Invalid value count " + valueCount);
384 }
385
386 Object[] array = new Object[valueCount];
387 for (int j = 0; j < valueCount; j++) {
388 array[j] = stream.readObject();
389 }
390 builder.put(key, ImmutableList.copyOf(array));
391 tmpSize += valueCount;
392 }
393
394 ImmutableMap<Object, ImmutableList<Object>> tmpMap;
395 try {
396 tmpMap = builder.build();
397 } catch (IllegalArgumentException e) {
398 throw (InvalidObjectException)
399 new InvalidObjectException(e.getMessage()).initCause(e);
400 }
401
402 FieldSettersHolder.MAP_FIELD_SETTER.set(this, tmpMap);
403 FieldSettersHolder.SIZE_FIELD_SETTER.set(this, tmpSize);
404 }
405
406 @GwtIncompatible("Not needed in emulated source")
407 private static final long serialVersionUID = 0;
408 }