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;
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     * @author Jared Levy
050     * @since 2 (imported from Google Collections Library)
051     */
052    @GwtCompatible(serializable = true, emulated = true)
053    public class ImmutableListMultimap<K, V>
054        extends ImmutableMultimap<K, V>
055        implements ListMultimap<K, V> {
056    
057      /** Returns the empty multimap. */
058      // Casting is safe because the multimap will never hold any elements.
059      @SuppressWarnings("unchecked")
060      public static <K, V> ImmutableListMultimap<K, V> of() {
061        return (ImmutableListMultimap<K, V>) EmptyImmutableListMultimap.INSTANCE;
062      }
063    
064      /**
065       * Returns an immutable multimap containing a single entry.
066       */
067      public static <K, V> ImmutableListMultimap<K, V> of(K k1, V v1) {
068        ImmutableListMultimap.Builder<K, V> builder
069            = ImmutableListMultimap.builder();
070        builder.put(k1, v1);
071        return builder.build();
072      }
073    
074      /**
075       * Returns an immutable multimap containing the given entries, in order.
076       */
077      public static <K, V> ImmutableListMultimap<K, V> of(K k1, V v1, K k2, V v2) {
078        ImmutableListMultimap.Builder<K, V> builder
079            = ImmutableListMultimap.builder();
080        builder.put(k1, v1);
081        builder.put(k2, v2);
082        return builder.build();
083      }
084    
085      /**
086       * Returns an immutable multimap containing the given entries, in order.
087       */
088      public static <K, V> ImmutableListMultimap<K, V> of(
089          K k1, V v1, K k2, V v2, K k3, V v3) {
090        ImmutableListMultimap.Builder<K, V> builder
091            = ImmutableListMultimap.builder();
092        builder.put(k1, v1);
093        builder.put(k2, v2);
094        builder.put(k3, v3);
095        return builder.build();
096      }
097    
098      /**
099       * Returns an immutable multimap containing the given entries, in order.
100       */
101      public static <K, V> ImmutableListMultimap<K, V> of(
102          K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4) {
103        ImmutableListMultimap.Builder<K, V> builder
104            = ImmutableListMultimap.builder();
105        builder.put(k1, v1);
106        builder.put(k2, v2);
107        builder.put(k3, v3);
108        builder.put(k4, v4);
109        return builder.build();
110      }
111    
112      /**
113       * Returns an immutable multimap containing the given entries, in order.
114       */
115      public static <K, V> ImmutableListMultimap<K, V> of(
116          K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5) {
117        ImmutableListMultimap.Builder<K, V> builder
118            = ImmutableListMultimap.builder();
119        builder.put(k1, v1);
120        builder.put(k2, v2);
121        builder.put(k3, v3);
122        builder.put(k4, v4);
123        builder.put(k5, v5);
124        return builder.build();
125      }
126    
127      // looking for of() with > 5 entries? Use the builder instead.
128    
129      /**
130       * Returns a new builder. The generated builder is equivalent to the builder
131       * created by the {@link Builder} constructor.
132       */
133      public static <K, V> Builder<K, V> builder() {
134        return new Builder<K, V>();
135      }
136    
137      /**
138       * A builder for creating immutable {@code ListMultimap} instances, especially
139       * {@code public static final} multimaps ("constant multimaps"). Example:
140       * <pre>   {@code
141       *
142       *   static final Multimap<String, Integer> STRING_TO_INTEGER_MULTIMAP =
143       *       new ImmutableListMultimap.Builder<String, Integer>()
144       *           .put("one", 1)
145       *           .putAll("several", 1, 2, 3)
146       *           .putAll("many", 1, 2, 3, 4, 5)
147       *           .build();}</pre>
148       *
149       * Builder instances can be reused; it is safe to call {@link #build} multiple
150       * times to build multiple multimaps in series. Each multimap contains the
151       * key-value mappings in the previously created multimaps.
152       *
153       * @since 2 (imported from Google Collections Library)
154       */
155      public static final class Builder<K, V>
156          extends ImmutableMultimap.Builder<K, V> {
157        /**
158         * Creates a new builder. The returned builder is equivalent to the builder
159         * generated by {@link ImmutableListMultimap#builder}.
160         */
161        public Builder() {}
162    
163        @Override public Builder<K, V> put(K key, V value) {
164          super.put(key, value);
165          return this;
166        }
167    
168        @Override public Builder<K, V> putAll(K key, Iterable<? extends V> values) {
169          super.putAll(key, values);
170          return this;
171        }
172    
173        @Override public Builder<K, V> putAll(K key, V... values) {
174          super.putAll(key, values);
175          return this;
176        }
177    
178        @Override public Builder<K, V> putAll(
179            Multimap<? extends K, ? extends V> multimap) {
180          super.putAll(multimap);
181          return this;
182        }
183    
184        /**
185         * {@inheritDoc}
186         *
187         * @since 8
188         */
189        @Beta @Override
190        public Builder<K, V> orderKeysBy(Comparator<? super K> keyComparator) {
191          super.orderKeysBy(keyComparator);
192          return this;
193        }
194    
195        /**
196         * {@inheritDoc}
197         *
198         * @since 8
199         */
200        @Beta @Override
201        public Builder<K, V> orderValuesBy(Comparator<? super V> valueComparator) {
202          super.orderValuesBy(valueComparator);
203          return this;
204        }
205    
206        /**
207         * Returns a newly-created immutable list multimap.
208         */
209        @Override public ImmutableListMultimap<K, V> build() {
210          return (ImmutableListMultimap<K, V>) super.build();
211        }
212      }
213    
214      /**
215       * Returns an immutable multimap containing the same mappings as {@code
216       * multimap}. The generated multimap's key and value orderings correspond to
217       * the iteration ordering of the {@code multimap.asMap()} view.
218       *
219       * <p>Despite the method name, this method attempts to avoid actually copying
220       * the data when it is safe to do so. The exact circumstances under which a
221       * copy will or will not be performed are undocumented and subject to change.
222       *
223       * @throws NullPointerException if any key or value in {@code multimap} is
224       *         null
225       */
226      public static <K, V> ImmutableListMultimap<K, V> copyOf(
227          Multimap<? extends K, ? extends V> multimap) {
228        if (multimap.isEmpty()) {
229          return of();
230        }
231    
232        // TODO(user): copy ImmutableSetMultimap by using asList() on the sets
233        if (multimap instanceof ImmutableListMultimap) {
234          @SuppressWarnings("unchecked") // safe since multimap is not writable
235          ImmutableListMultimap<K, V> kvMultimap
236              = (ImmutableListMultimap<K, V>) multimap;
237          if (!kvMultimap.isPartialView()) {
238            return kvMultimap;
239          }
240        }
241    
242        ImmutableMap.Builder<K, ImmutableList<V>> builder = ImmutableMap.builder();
243        int size = 0;
244    
245        for (Map.Entry<? extends K, ? extends Collection<? extends V>> entry
246            : multimap.asMap().entrySet()) {
247          ImmutableList<V> list = ImmutableList.copyOf(entry.getValue());
248          if (!list.isEmpty()) {
249            builder.put(entry.getKey(), list);
250            size += list.size();
251          }
252        }
253    
254        return new ImmutableListMultimap<K, V>(builder.build(), size);
255      }
256    
257      ImmutableListMultimap(ImmutableMap<K, ImmutableList<V>> map, int size) {
258        super(map, size);
259      }
260    
261      // views
262    
263      /**
264       * Returns an immutable list of the values for the given key.  If no mappings
265       * in the multimap have the provided key, an empty immutable list is
266       * returned. The values are in the same order as the parameters used to build
267       * this multimap.
268       */
269      @Override public ImmutableList<V> get(@Nullable K key) {
270        // This cast is safe as its type is known in constructor.
271        ImmutableList<V> list = (ImmutableList<V>) map.get(key);
272        return (list == null) ? ImmutableList.<V>of() : list;
273      }
274    
275      /**
276       * Guaranteed to throw an exception and leave the multimap unmodified.
277       *
278       * @throws UnsupportedOperationException always
279       */
280      @Override public ImmutableList<V> removeAll(Object key) {
281        throw new UnsupportedOperationException();
282      }
283    
284      /**
285       * Guaranteed to throw an exception and leave the multimap unmodified.
286       *
287       * @throws UnsupportedOperationException always
288       */
289      @Override public ImmutableList<V> replaceValues(
290          K key, Iterable<? extends V> values) {
291        throw new UnsupportedOperationException();
292      }
293    
294      /**
295       * @serialData number of distinct keys, and then for each distinct key: the
296       *     key, the number of values for that key, and the key's values
297       */
298      @GwtIncompatible("java.io.ObjectOutputStream")
299      private void writeObject(ObjectOutputStream stream) throws IOException {
300        stream.defaultWriteObject();
301        Serialization.writeMultimap(this, stream);
302      }
303    
304      @GwtIncompatible("java.io.ObjectInputStream")
305      private void readObject(ObjectInputStream stream)
306          throws IOException, ClassNotFoundException {
307        stream.defaultReadObject();
308        int keyCount = stream.readInt();
309        if (keyCount < 0) {
310          throw new InvalidObjectException("Invalid key count " + keyCount);
311        }
312        ImmutableMap.Builder<Object, ImmutableList<Object>> builder
313            = ImmutableMap.builder();
314        int tmpSize = 0;
315    
316        for (int i = 0; i < keyCount; i++) {
317          Object key = stream.readObject();
318          int valueCount = stream.readInt();
319          if (valueCount <= 0) {
320            throw new InvalidObjectException("Invalid value count " + valueCount);
321          }
322    
323          Object[] array = new Object[valueCount];
324          for (int j = 0; j < valueCount; j++) {
325            array[j] = stream.readObject();
326          }
327          builder.put(key, ImmutableList.copyOf(array));
328          tmpSize += valueCount;
329        }
330    
331        ImmutableMap<Object, ImmutableList<Object>> tmpMap;
332        try {
333          tmpMap = builder.build();
334        } catch (IllegalArgumentException e) {
335          throw (InvalidObjectException)
336              new InvalidObjectException(e.getMessage()).initCause(e);
337        }
338    
339        FieldSettersHolder.MAP_FIELD_SETTER.set(this, tmpMap);
340        FieldSettersHolder.SIZE_FIELD_SETTER.set(this, tmpSize);
341      }
342    
343      @GwtIncompatible("Not needed in emulated source")
344      private static final long serialVersionUID = 0;
345    }