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/*
* Copyright (C) 2007 Google Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.google.common.collect;
import com.google.common.annotations.GwtCompatible;
import com.google.common.base.Function;
import com.google.common.base.Joiner;
import com.google.common.base.Joiner.MapJoiner;
import com.google.common.base.Preconditions;
import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.base.Preconditions.checkState;
import com.google.common.base.Supplier;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.util.AbstractSet;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.NoSuchElementException;
import java.util.Set;
import java.util.SortedSet;
import javax.annotation.Nullable;
/**
* Provides static methods acting on or generating a {@code Multimap}.
*
* @author Jared Levy
* @author Robert Konigsberg
* @author Mike Bostock
*/
@GwtCompatible
public final class Multimaps {
private Multimaps() {}
/**
* Creates a new {@code Multimap} that uses the provided map and factory. It
* can generate a multimap based on arbitrary {@link Map} and
* {@link Collection} classes.
*
* The {@code factory}-generated and {@code map} classes determine the
* multimap iteration order. They also specify the behavior of the
* {@code equals}, {@code hashCode}, and {@code toString} methods for the
* multimap and its returned views. However, the multimap's {@code get}
* method returns instances of a different class than {@code factory.get()}
* does.
*
*
The multimap is serializable if {@code map}, {@code factory}, the
* collections generated by {@code factory}, and the multimap contents are all
* serializable.
*
*
The multimap is not threadsafe when any concurrent operations update the
* multimap, even if {@code map} and the instances generated by
* {@code factory} are. Concurrent read operations will work correctly. To
* allow concurrent update operations, wrap the multimap with a call to
* {@link #synchronizedMultimap}.
*
*
Call this method only when the simpler methods
* {@link ArrayListMultimap#create()}, {@link HashMultimap#create()},
* {@link LinkedHashMultimap#create()}, {@link LinkedListMultimap#create()},
* {@link TreeMultimap#create()}, and
* {@link TreeMultimap#create(Comparator, Comparator)} won't suffice.
*
*
Note: the multimap assumes complete ownership over of {@code map} and
* the collections returned by {@code factory}. Those objects should not be
* manually updated and they should not use soft, weak, or phantom references.
*
* @param map place to store the mapping from each key to its corresponding
* values
* @param factory supplier of new, empty collections that will each hold all
* values for a given key
* @throws IllegalArgumentException if {@code map} is not empty
*/
public static Multimap newMultimap(Map> map,
final Supplier> factory) {
return new CustomMultimap(map, factory);
}
private static class CustomMultimap extends AbstractMultimap {
transient Supplier> factory;
CustomMultimap(Map> map,
Supplier> factory) {
super(map);
this.factory = checkNotNull(factory);
}
@Override protected Collection createCollection() {
return factory.get();
}
// can't use Serialization writeMultimap and populateMultimap methods since
// there's no way to generate the empty backing map.
/** @serialData the factory and the backing map */
private void writeObject(ObjectOutputStream stream) throws IOException {
stream.defaultWriteObject();
stream.writeObject(factory);
stream.writeObject(backingMap());
}
@SuppressWarnings("unchecked") // reading data stored by writeObject
private void readObject(ObjectInputStream stream)
throws IOException, ClassNotFoundException {
stream.defaultReadObject();
factory = (Supplier>) stream.readObject();
Map> map = (Map>) stream.readObject();
setMap(map);
}
private static final long serialVersionUID = 0;
}
/**
* Creates a new {@code ListMultimap} that uses the provided map and factory.
* It can generate a multimap based on arbitrary {@link Map} and {@link List}
* classes.
*
* The {@code factory}-generated and {@code map} classes determine the
* multimap iteration order. They also specify the behavior of the
* {@code equals}, {@code hashCode}, and {@code toString} methods for the
* multimap and its returned views. The multimap's {@code get}, {@code
* removeAll}, and {@code replaceValues} methods return {@code RandomAccess}
* lists if the factory does. However, the multimap's {@code get} method
* returns instances of a different class than does {@code factory.get()}.
*
*
The multimap is serializable if {@code map}, {@code factory}, the
* lists generated by {@code factory}, and the multimap contents are all
* serializable.
*
*
The multimap is not threadsafe when any concurrent operations update the
* multimap, even if {@code map} and the instances generated by
* {@code factory} are. Concurrent read operations will work correctly. To
* allow concurrent update operations, wrap the multimap with a call to
* {@link #synchronizedListMultimap}.
*
*
Call this method only when the simpler methods
* {@link ArrayListMultimap#create()} and {@link LinkedListMultimap#create()}
* won't suffice.
*
*
Note: the multimap assumes complete ownership over of {@code map} and
* the lists returned by {@code factory}. Those objects should not be manually
* updated and they should not use soft, weak, or phantom references.
*
* @param map place to store the mapping from each key to its corresponding
* values
* @param factory supplier of new, empty lists that will each hold all values
* for a given key
* @throws IllegalArgumentException if {@code map} is not empty
*/
public static ListMultimap newListMultimap(
Map> map, final Supplier> factory) {
return new CustomListMultimap(map, factory);
}
private static class CustomListMultimap
extends AbstractListMultimap {
transient Supplier> factory;
CustomListMultimap(Map> map,
Supplier> factory) {
super(map);
this.factory = checkNotNull(factory);
}
@Override protected List createCollection() {
return factory.get();
}
/** @serialData the factory and the backing map */
private void writeObject(ObjectOutputStream stream) throws IOException {
stream.defaultWriteObject();
stream.writeObject(factory);
stream.writeObject(backingMap());
}
@SuppressWarnings("unchecked") // reading data stored by writeObject
private void readObject(ObjectInputStream stream)
throws IOException, ClassNotFoundException {
stream.defaultReadObject();
factory = (Supplier>) stream.readObject();
Map> map = (Map>) stream.readObject();
setMap(map);
}
private static final long serialVersionUID = 0;
}
/**
* Creates a new {@code SetMultimap} that uses the provided map and factory.
* It can generate a multimap based on arbitrary {@link Map} and {@link Set}
* classes.
*
* The {@code factory}-generated and {@code map} classes determine the
* multimap iteration order. They also specify the behavior of the
* {@code equals}, {@code hashCode}, and {@code toString} methods for the
* multimap and its returned views. However, the multimap's {@code get}
* method returns instances of a different class than {@code factory.get()}
* does.
*
*
The multimap is serializable if {@code map}, {@code factory}, the
* sets generated by {@code factory}, and the multimap contents are all
* serializable.
*
*
The multimap is not threadsafe when any concurrent operations update the
* multimap, even if {@code map} and the instances generated by
* {@code factory} are. Concurrent read operations will work correctly. To
* allow concurrent update operations, wrap the multimap with a call to
* {@link #synchronizedSetMultimap}.
*
*
Call this method only when the simpler methods
* {@link HashMultimap#create()}, {@link LinkedHashMultimap#create()},
* {@link TreeMultimap#create()}, and
* {@link TreeMultimap#create(Comparator, Comparator)} won't suffice.
*
*
Note: the multimap assumes complete ownership over of {@code map} and
* the sets returned by {@code factory}. Those objects should not be manually
* updated and they should not use soft, weak, or phantom references.
*
* @param map place to store the mapping from each key to its corresponding
* values
* @param factory supplier of new, empty sets that will each hold all values
* for a given key
* @throws IllegalArgumentException if {@code map} is not empty
*/
public static SetMultimap newSetMultimap(
Map> map, final Supplier> factory) {
return new CustomSetMultimap(map, factory);
}
private static class CustomSetMultimap
extends AbstractSetMultimap {
transient Supplier> factory;
CustomSetMultimap(Map> map,
Supplier> factory) {
super(map);
this.factory = checkNotNull(factory);
}
@Override protected Set createCollection() {
return factory.get();
}
/** @serialData the factory and the backing map */
private void writeObject(ObjectOutputStream stream) throws IOException {
stream.defaultWriteObject();
stream.writeObject(factory);
stream.writeObject(backingMap());
}
@SuppressWarnings("unchecked") // reading data stored by writeObject
private void readObject(ObjectInputStream stream)
throws IOException, ClassNotFoundException {
stream.defaultReadObject();
factory = (Supplier>) stream.readObject();
Map> map = (Map>) stream.readObject();
setMap(map);
}
private static final long serialVersionUID = 0;
}
/**
* Creates a new {@code SortedSetMultimap} that uses the provided map and
* factory. It can generate a multimap based on arbitrary {@link Map} and
* {@link SortedSet} classes.
*
* The {@code factory}-generated and {@code map} classes determine the
* multimap iteration order. They also specify the behavior of the
* {@code equals}, {@code hashCode}, and {@code toString} methods for the
* multimap and its returned views. However, the multimap's {@code get}
* method returns instances of a different class than {@code factory.get()}
* does.
*
*
The multimap is serializable if {@code map}, {@code factory}, the
* sets generated by {@code factory}, and the multimap contents are all
* serializable.
*
*
The multimap is not threadsafe when any concurrent operations update the
* multimap, even if {@code map} and the instances generated by
* {@code factory} are. Concurrent read operations will work correctly. To
* allow concurrent update operations, wrap the multimap with a call to
* {@link #synchronizedSortedSetMultimap}.
*
*
Call this method only when the simpler methods
* {@link TreeMultimap#create()} and
* {@link TreeMultimap#create(Comparator, Comparator)} won't suffice.
*
*
Note: the multimap assumes complete ownership over of {@code map} and
* the sets returned by {@code factory}. Those objects should not be manually
* updated and they should not use soft, weak, or phantom references.
*
* @param map place to store the mapping from each key to its corresponding
* values
* @param factory supplier of new, empty sorted sets that will each hold
* all values for a given key
* @throws IllegalArgumentException if {@code map} is not empty
*/
public static SortedSetMultimap newSortedSetMultimap(
Map> map,
final Supplier> factory) {
return new CustomSortedSetMultimap(map, factory);
}
private static class CustomSortedSetMultimap
extends AbstractSortedSetMultimap {
transient Supplier> factory;
transient Comparator valueComparator;
CustomSortedSetMultimap(Map> map,
Supplier> factory) {
super(map);
this.factory = checkNotNull(factory);
valueComparator = factory.get().comparator();
}
@Override protected SortedSet createCollection() {
return factory.get();
}
/*@Override*/ public Comparator valueComparator() {
return valueComparator;
}
/** @serialData the factory and the backing map */
private void writeObject(ObjectOutputStream stream) throws IOException {
stream.defaultWriteObject();
stream.writeObject(factory);
stream.writeObject(backingMap());
}
@SuppressWarnings("unchecked") // reading data stored by writeObject
private void readObject(ObjectInputStream stream)
throws IOException, ClassNotFoundException {
stream.defaultReadObject();
factory = (Supplier>) stream.readObject();
valueComparator = factory.get().comparator();
Map> map = (Map>) stream.readObject();
setMap(map);
}
private static final long serialVersionUID = 0;
}
/**
* Copies each key-value mapping in {@code source} into {@code dest}, with
* its key and value reversed.
*
* @param source any multimap
* @param dest the multimap to copy into; usually empty
* @return {@code dest}
*/
public static > M invertFrom(
Multimap source, M dest) {
for (Map.Entry entry : source.entries()) {
dest.put(entry.getValue(), entry.getKey());
}
return dest;
}
/**
* Returns a synchronized (thread-safe) multimap backed by the specified
* multimap. In order to guarantee serial access, it is critical that
* all access to the backing multimap is accomplished through the
* returned multimap.
*
* It is imperative that the user manually synchronize on the returned
* multimap when accessing any of its collection views:
{@code
*
* Multimap m = Multimaps.synchronizedMultimap(
* HashMultimap.create());
* ...
* Set s = m.keySet(); // Needn't be in synchronized block
* ...
* synchronized (m) { // Synchronizing on m, not s!
* Iterator i = s.iterator(); // Must be in synchronized block
* while (i.hasNext()) {
* foo(i.next());
* }
* }}
*
* Failure to follow this advice may result in non-deterministic behavior.
*
* Note that the generated multimap's {@link Multimap#removeAll} and
* {@link Multimap#replaceValues} methods return collections that aren't
* synchronized.
*
*
The returned multimap will be serializable if the specified multimap is
* serializable.
*
* @param multimap the multimap to be wrapped in a synchronized view
* @return a synchronized view of the specified multimap
*/
public static Multimap synchronizedMultimap(
Multimap multimap) {
return Synchronized.multimap(multimap, null);
}
/**
* Returns an unmodifiable view of the specified multimap. Query operations on
* the returned multimap "read through" to the specified multimap, and
* attempts to modify the returned multimap, either directly or through the
* multimap's views, result in an {@code UnsupportedOperationException}.
*
* Note that the generated multimap's {@link Multimap#removeAll} and
* {@link Multimap#replaceValues} methods return collections that are
* modifiable.
*
*
The returned multimap will be serializable if the specified multimap is
* serializable.
*
* @param delegate the multimap for which an unmodifiable view is to be
* returned
* @return an unmodifiable view of the specified multimap
*/
public static Multimap unmodifiableMultimap(
Multimap delegate) {
return new UnmodifiableMultimap(delegate);
}
private static class UnmodifiableMultimap
extends ForwardingMultimap implements Serializable {
final Multimap delegate;
transient Collection> entries;
transient Multiset keys;
transient Set keySet;
transient Collection values;
transient Map> map;
UnmodifiableMultimap(final Multimap delegate) {
this.delegate = delegate;
}
@Override protected Multimap delegate() {
return delegate;
}
@Override public void clear() {
throw new UnsupportedOperationException();
}
@Override public Map> asMap() {
Map> result = map;
if (result == null) {
final Map> unmodifiableMap
= Collections.unmodifiableMap(delegate.asMap());
map = result = new ForwardingMap>() {
@Override protected Map> delegate() {
return unmodifiableMap;
}
Set>> entrySet;
@Override public Set>> entrySet() {
Set>> result = entrySet;
return (result == null)
? entrySet
= unmodifiableAsMapEntries(unmodifiableMap.entrySet())
: result;
}
@Override public Collection get(Object key) {
Collection collection = unmodifiableMap.get(key);
return (collection == null)
? null : unmodifiableValueCollection(collection);
}
Collection> asMapValues;
@Override public Collection> values() {
Collection> result = asMapValues;
return (result == null)
? asMapValues
= new UnmodifiableAsMapValues(unmodifiableMap.values())
: result;
}
@Override public boolean containsValue(Object o) {
return values().contains(o);
}
};
}
return result;
}
@Override public Collection> entries() {
Collection> result = entries;
if (result == null) {
entries = result = unmodifiableEntries(delegate.entries());
}
return result;
}
@Override public Collection get(K key) {
return unmodifiableValueCollection(delegate.get(key));
}
@Override public Multiset keys() {
Multiset result = keys;
if (result == null) {
keys = result = Multisets.unmodifiableMultiset(delegate.keys());
}
return result;
}
@Override public Set keySet() {
Set result = keySet;
if (result == null) {
keySet = result = Collections.unmodifiableSet(delegate.keySet());
}
return result;
}
@Override public boolean put(K key, V value) {
throw new UnsupportedOperationException();
}
@Override public boolean putAll(K key,
@SuppressWarnings("hiding") Iterable values) {
throw new UnsupportedOperationException();
}
@Override
public boolean putAll(Multimap multimap) {
throw new UnsupportedOperationException();
}
@Override public boolean remove(Object key, Object value) {
throw new UnsupportedOperationException();
}
@Override public Collection removeAll(Object key) {
throw new UnsupportedOperationException();
}
@Override public Collection replaceValues(K key,
@SuppressWarnings("hiding") Iterable values) {
throw new UnsupportedOperationException();
}
@Override public Collection values() {
Collection result = values;
if (result == null) {
values = result = Collections.unmodifiableCollection(delegate.values());
}
return result;
}
private static final long serialVersionUID = 0;
}
private static class UnmodifiableAsMapValues
extends ForwardingCollection> {
final Collection> delegate;
UnmodifiableAsMapValues(Collection> delegate) {
this.delegate = Collections.unmodifiableCollection(delegate);
}
@Override protected Collection> delegate() {
return delegate;
}
@Override public Iterator> iterator() {
final Iterator> iterator = delegate.iterator();
return new Iterator>() {
public boolean hasNext() {
return iterator.hasNext();
}
public Collection next() {
return unmodifiableValueCollection(iterator.next());
}
public void remove() {
throw new UnsupportedOperationException();
}
};
}
@Override public Object[] toArray() {
return ObjectArrays.toArrayImpl(this);
}
@Override public T[] toArray(T[] array) {
return ObjectArrays.toArrayImpl(this, array);
}
@Override public boolean contains(Object o) {
return Iterators.contains(iterator(), o);
}
@Override public boolean containsAll(Collection c) {
return Collections2.containsAll(this, c);
}
}
private static class UnmodifiableListMultimap
extends UnmodifiableMultimap implements ListMultimap {
UnmodifiableListMultimap(ListMultimap delegate) {
super(delegate);
}
@Override public ListMultimap delegate() {
return (ListMultimap) super.delegate();
}
@Override public List get(K key) {
return Collections.unmodifiableList(delegate().get(key));
}
@Override public List removeAll(Object key) {
throw new UnsupportedOperationException();
}
@Override public List replaceValues(
K key, @SuppressWarnings("hiding") Iterable values) {
throw new UnsupportedOperationException();
}
private static final long serialVersionUID = 0;
}
private static class UnmodifiableSetMultimap
extends UnmodifiableMultimap implements SetMultimap {
UnmodifiableSetMultimap(SetMultimap delegate) {
super(delegate);
}
@Override public SetMultimap delegate() {
return (SetMultimap) super.delegate();
}
@Override public Set get(K key) {
/*
* Note that this doesn't return a SortedSet when delegate is a
* SortedSetMultiset, unlike (SortedSet) super.get().
*/
return Collections.unmodifiableSet(delegate().get(key));
}
@Override public Set> entries() {
return Maps.unmodifiableEntrySet(delegate().entries());
}
@Override public Set removeAll(Object key) {
throw new UnsupportedOperationException();
}
@Override public Set replaceValues(
K key, @SuppressWarnings("hiding") Iterable values) {
throw new UnsupportedOperationException();
}
private static final long serialVersionUID = 0;
}
private static class UnmodifiableSortedSetMultimap
extends UnmodifiableSetMultimap implements SortedSetMultimap {
UnmodifiableSortedSetMultimap(SortedSetMultimap delegate) {
super(delegate);
}
@Override public SortedSetMultimap delegate() {
return (SortedSetMultimap) super.delegate();
}
@Override public SortedSet get(K key) {
return Collections.unmodifiableSortedSet(delegate().get(key));
}
@Override public SortedSet removeAll(Object key) {
throw new UnsupportedOperationException();
}
@Override public SortedSet replaceValues(
K key, @SuppressWarnings("hiding") Iterable values) {
throw new UnsupportedOperationException();
}
public Comparator valueComparator() {
return delegate().valueComparator();
}
private static final long serialVersionUID = 0;
}
/**
* Returns a synchronized (thread-safe) {@code SetMultimap} backed by the
* specified multimap.
*
* You must follow the warnings described in {@link #synchronizedMultimap}.
*
*
The returned multimap will be serializable if the specified multimap is
* serializable.
*
* @param multimap the multimap to be wrapped
* @return a synchronized view of the specified multimap
*/
public static SetMultimap synchronizedSetMultimap(
SetMultimap multimap) {
return Synchronized.setMultimap(multimap, null);
}
/**
* Returns an unmodifiable view of the specified {@code SetMultimap}. Query
* operations on the returned multimap "read through" to the specified
* multimap, and attempts to modify the returned multimap, either directly or
* through the multimap's views, result in an
* {@code UnsupportedOperationException}.
*
* Note that the generated multimap's {@link Multimap#removeAll} and
* {@link Multimap#replaceValues} methods return collections that are
* modifiable.
*
*
The returned multimap will be serializable if the specified multimap is
* serializable.
*
* @param delegate the multimap for which an unmodifiable view is to be
* returned
* @return an unmodifiable view of the specified multimap
*/
public static SetMultimap unmodifiableSetMultimap(
SetMultimap delegate) {
return new UnmodifiableSetMultimap(delegate);
}
/**
* Returns a synchronized (thread-safe) {@code SortedSetMultimap} backed by
* the specified multimap.
*
* You must follow the warnings described in {@link #synchronizedMultimap}.
*
*
The returned multimap will be serializable if the specified multimap is
* serializable.
*
* @param multimap the multimap to be wrapped
* @return a synchronized view of the specified multimap
*/
public static SortedSetMultimap
synchronizedSortedSetMultimap(SortedSetMultimap multimap) {
return Synchronized.sortedSetMultimap(multimap, null);
}
/**
* Returns an unmodifiable view of the specified {@code SortedSetMultimap}.
* Query operations on the returned multimap "read through" to the specified
* multimap, and attempts to modify the returned multimap, either directly or
* through the multimap's views, result in an
* {@code UnsupportedOperationException}.
*
* Note that the generated multimap's {@link Multimap#removeAll} and
* {@link Multimap#replaceValues} methods return collections that are
* modifiable.
*
*
The returned multimap will be serializable if the specified multimap is
* serializable.
*
* @param delegate the multimap for which an unmodifiable view is to be
* returned
* @return an unmodifiable view of the specified multimap
*/
public static SortedSetMultimap unmodifiableSortedSetMultimap(
SortedSetMultimap delegate) {
return new UnmodifiableSortedSetMultimap(delegate);
}
/**
* Returns a synchronized (thread-safe) {@code ListMultimap} backed by the
* specified multimap.
*
* You must follow the warnings described in {@link #synchronizedMultimap}.
*
* @param multimap the multimap to be wrapped
* @return a synchronized view of the specified multimap
*/
public static ListMultimap synchronizedListMultimap(
ListMultimap multimap) {
return Synchronized.listMultimap(multimap, null);
}
/**
* Returns an unmodifiable view of the specified {@code ListMultimap}. Query
* operations on the returned multimap "read through" to the specified
* multimap, and attempts to modify the returned multimap, either directly or
* through the multimap's views, result in an
* {@code UnsupportedOperationException}.
*
* Note that the generated multimap's {@link Multimap#removeAll} and
* {@link Multimap#replaceValues} methods return collections that are
* modifiable.
*
*
The returned multimap will be serializable if the specified multimap is
* serializable.
*
* @param delegate the multimap for which an unmodifiable view is to be
* returned
* @return an unmodifiable view of the specified multimap
*/
public static ListMultimap unmodifiableListMultimap(
ListMultimap delegate) {
return new UnmodifiableListMultimap(delegate);
}
/**
* Returns an unmodifiable view of the specified collection, preserving the
* interface for instances of {@code SortedSet}, {@code Set}, {@code List} and
* {@code Collection}, in that order of preference.
*
* @param collection the collection for which to return an unmodifiable view
* @return an unmodifiable view of the collection
*/
private static Collection unmodifiableValueCollection(
Collection collection) {
if (collection instanceof SortedSet) {
return Collections.unmodifiableSortedSet((SortedSet) collection);
} else if (collection instanceof Set) {
return Collections.unmodifiableSet((Set) collection);
} else if (collection instanceof List) {
return Collections.unmodifiableList((List) collection);
}
return Collections.unmodifiableCollection(collection);
}
/**
* Returns an unmodifiable view of the specified multimap {@code asMap} entry.
* The {@link Entry#setValue} operation throws an {@link
* UnsupportedOperationException}, and the collection returned by {@code
* getValue} is also an unmodifiable (type-preserving) view. This also has the
* side-effect of redefining equals to comply with the Map.Entry contract, and
* to avoid a possible nefarious implementation of equals.
*
* @param entry the entry for which to return an unmodifiable view
* @return an unmodifiable view of the entry
*/
private static Map.Entry> unmodifiableAsMapEntry(
final Map.Entry> entry) {
checkNotNull(entry);
return new AbstractMapEntry>() {
@Override public K getKey() {
return entry.getKey();
}
@Override public Collection getValue() {
return unmodifiableValueCollection(entry.getValue());
}
};
}
/**
* Returns an unmodifiable view of the specified collection of entries. The
* {@link Entry#setValue} operation throws an {@link
* UnsupportedOperationException}. If the specified collection is a {@code
* Set}, the returned collection is also a {@code Set}.
*
* @param entries the entries for which to return an unmodifiable view
* @return an unmodifiable view of the entries
*/
private static Collection> unmodifiableEntries(
Collection> entries) {
if (entries instanceof Set) {
return Maps.unmodifiableEntrySet((Set>) entries);
}
return new Maps.UnmodifiableEntries(
Collections.unmodifiableCollection(entries));
}
/**
* Returns an unmodifiable view of the specified set of {@code asMap} entries.
* The {@link Entry#setValue} operation throws an {@link
* UnsupportedOperationException}, as do any operations that attempt to modify
* the returned collection.
*
* @param asMapEntries the {@code asMap} entries for which to return an
* unmodifiable view
* @return an unmodifiable view of the collection entries
*/
private static Set>> unmodifiableAsMapEntries(
Set>> asMapEntries) {
return new UnmodifiableAsMapEntries(
Collections.unmodifiableSet(asMapEntries));
}
/** @see Multimaps#unmodifiableAsMapEntries */
static class UnmodifiableAsMapEntries
extends ForwardingSet>> {
private final Set>> delegate;
UnmodifiableAsMapEntries(Set>> delegate) {
this.delegate = delegate;
}
@Override protected Set>> delegate() {
return delegate;
}
@Override public Iterator>> iterator() {
final Iterator>> iterator = delegate.iterator();
return new ForwardingIterator>>() {
@Override protected Iterator>> delegate() {
return iterator;
}
@Override public Entry> next() {
return unmodifiableAsMapEntry(iterator.next());
}
};
}
@Override public Object[] toArray() {
return ObjectArrays.toArrayImpl(this);
}
@Override public T[] toArray(T[] array) {
return ObjectArrays.toArrayImpl(this, array);
}
@Override public boolean contains(Object o) {
return Maps.containsEntryImpl(delegate(), o);
}
@Override public boolean containsAll(Collection c) {
return Collections2.containsAll(this, c);
}
@Override public boolean equals(@Nullable Object object) {
return Collections2.setEquals(this, object);
}
}
/**
* Returns a multimap view of the specified map. The multimap is backed by the
* map, so changes to the map are reflected in the multimap, and vice versa.
* If the map is modified while an iteration over one of the multimap's
* collection views is in progress (except through the iterator's own {@code
* remove} operation, or through the {@code setValue} operation on a map entry
* returned by the iterator), the results of the iteration are undefined.
*
* The multimap supports mapping removal, which removes the corresponding
* mapping from the map. It does not support any operations which might add
* mappings, such as {@code put}, {@code putAll} or {@code replaceValues}.
*
*
The returned multimap will be serializable if the specified map is
* serializable.
*
* @param map the backing map for the returned multimap view
*/
public static SetMultimap forMap(Map map) {
return new MapMultimap(map);
}
/** @see Multimaps#forMap */
private static class MapMultimap
implements SetMultimap, Serializable {
final Map map;
transient Map> asMap;
MapMultimap(Map map) {
this.map = checkNotNull(map);
}
public int size() {
return map.size();
}
public boolean isEmpty() {
return map.isEmpty();
}
public boolean containsKey(Object key) {
return map.containsKey(key);
}
public boolean containsValue(Object value) {
return map.containsValue(value);
}
public boolean containsEntry(Object key, Object value) {
return map.entrySet().contains(Maps.immutableEntry(key, value));
}
public Set get(final K key) {
return new AbstractSet() {
@Override public Iterator iterator() {
return new Iterator() {
int i;
public boolean hasNext() {
return (i == 0) && map.containsKey(key);
}
public V next() {
if (!hasNext()) {
throw new NoSuchElementException();
}
i++;
return map.get(key);
}
public void remove() {
checkState(i == 1);
i = -1;
map.remove(key);
}
};
}
@Override public int size() {
return map.containsKey(key) ? 1 : 0;
}
};
}
public boolean put(K key, V value) {
throw new UnsupportedOperationException();
}
public boolean putAll(K key, Iterable values) {
throw new UnsupportedOperationException();
}
public boolean putAll(Multimap multimap) {
throw new UnsupportedOperationException();
}
public Set replaceValues(K key, Iterable values) {
throw new UnsupportedOperationException();
}
public boolean remove(Object key, Object value) {
return map.entrySet().remove(Maps.immutableEntry(key, value));
}
public Set removeAll(Object key) {
Set values = new HashSet(2);
if (!map.containsKey(key)) {
return values;
}
values.add(map.remove(key));
return values;
}
public void clear() {
map.clear();
}
public Set keySet() {
return map.keySet();
}
public Multiset keys() {
return Multisets.forSet(map.keySet());
}
public Collection values() {
return map.values();
}
public Set> entries() {
return map.entrySet();
}
public Map> asMap() {
Map> result = asMap;
if (result == null) {
asMap = result = new AsMap();
}
return result;
}
@Override public boolean equals(@Nullable Object object) {
if (object == this) {
return true;
}
if (object instanceof Multimap) {
Multimap that = (Multimap) object;
return this.size() == that.size() && asMap().equals(that.asMap());
}
return false;
}
@Override public int hashCode() {
return map.hashCode();
}
private static final MapJoiner joiner
= Joiner.on("], ").withKeyValueSeparator("=[").useForNull("null");
@Override public String toString() {
if (map.isEmpty()) {
return "{}";
}
StringBuilder builder = new StringBuilder(map.size() * 16).append('{');
joiner.appendTo(builder, map);
return builder.append("]}").toString();
}
/** @see MapMultimap#asMap */
class AsMapEntries extends AbstractSet>> {
@Override public int size() {
return map.size();
}
@Override public Iterator>> iterator() {
return new Iterator>>() {
final Iterator keys = map.keySet().iterator();
public boolean hasNext() {
return keys.hasNext();
}
public Entry> next() {
final K key = keys.next();
return new AbstractMapEntry>() {
@Override public K getKey() {
return key;
}
@Override public Collection getValue() {
return get(key);
}
};
}
public void remove() {
keys.remove();
}
};
}
@Override public boolean contains(Object o) {
if (!(o instanceof Entry)) {
return false;
}
Entry entry = (Entry) o;
if (!(entry.getValue() instanceof Set)) {
return false;
}
Set set = (Set) entry.getValue();
return (set.size() == 1)
&& containsEntry(entry.getKey(), set.iterator().next());
}
@Override public boolean remove(Object o) {
if (!(o instanceof Entry)) {
return false;
}
Entry entry = (Entry) o;
if (!(entry.getValue() instanceof Set)) {
return false;
}
Set set = (Set) entry.getValue();
return (set.size() == 1)
&& map.entrySet().remove(
Maps.immutableEntry(entry.getKey(), set.iterator().next()));
}
}
/** @see MapMultimap#asMap */
class AsMap extends Maps.ImprovedAbstractMap> {
@Override protected Set>> createEntrySet() {
return new AsMapEntries();
}
// The following methods are included for performance.
@Override public boolean containsKey(Object key) {
return map.containsKey(key);
}
@SuppressWarnings("unchecked")
@Override public Collection get(Object key) {
Collection collection = MapMultimap.this.get((K) key);
return collection.isEmpty() ? null : collection;
}
@Override public Collection remove(Object key) {
Collection collection = removeAll(key);
return collection.isEmpty() ? null : collection;
}
}
private static final long serialVersionUID = 7845222491160860175L;
}
/**
* Creates an index {@code ImmutableMultimap} that contains the results of
* applying a specified function to each item in an {@code Iterable} of
* values. Each value will be stored as a value in the resulting multimap,
* yielding a multimap with the same size as the input iterable. The key used
* to store that value in the multimap will be the result of calling the
* function on that value. The resulting multimap is created as an immutable
* snapshot, it does not reflect subsequent changes on the input
* iterable.
*
* For example,
{@code
*
* List badGuys
* = Arrays.asList("Inky", "Blinky", "Pinky", "Pinky", "Clyde");
* Function stringLengthFunction = ...;
* Multimap index
* = Multimaps.index(badGuys, stringLengthFunction);
* System.out.println(index);}
*
* prints {@code
*
* {4=[Inky], 5=[Pinky, Pinky, Clyde], 6=[Blinky]}}
*
* The returned multimap is serializable if its keys and values are all
* serializable.
*
* @param values the values to use when constructing the {@code
* ImmutableMultimap}
* @param keyFunction the function used to produce the key for each value
* @return {@code ImmutableMultimap} mapping the result of evaluating the
* function {@code keyFunction} on each value in the input collection to
* that value
* @throws NullPointerException if any of the following cases is true:
* - {@code values} is null
*
- {@code keyFunction} is null
*
- An element in {@code values} is null
*
- {@code keyFunction} returns null for any element of {@code values}
*
*/
public static ImmutableListMultimap index(
Iterable values, Function keyFunction) {
checkNotNull(keyFunction);
ImmutableListMultimap.Builder builder
= ImmutableListMultimap.builder();
for (V value : values) {
Preconditions.checkNotNull(value, values);
builder.put(keyFunction.apply(value), value);
}
return builder.build();
}
}