/*
* Copyright (C) 2007 The Guava Authors
*
* 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 static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.base.Preconditions.checkState;
import com.google.common.annotations.GwtCompatible;
import java.io.Serializable;
import java.util.AbstractCollection;
import java.util.AbstractMap;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.ConcurrentModificationException;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;
import java.util.Map;
import java.util.Map.Entry;
import java.util.RandomAccess;
import java.util.Set;
import java.util.SortedMap;
import java.util.SortedSet;
import javax.annotation.Nullable;
/**
* Basic implementation of the {@link Multimap} interface. This class represents
* a multimap as a map that associates each key with a collection of values. All
* methods of {@link Multimap} are supported, including those specified as
* optional in the interface.
*
* <p>To implement a multimap, a subclass must define the method {@link
* #createCollection()}, which creates an empty collection of values for a key.
*
* <p>The multimap constructor takes a map that has a single entry for each
* distinct key. When you insert a key-value pair with a key that isn't already
* in the multimap, {@code AbstractMultimap} calls {@link #createCollection()}
* to create the collection of values for that key. The subclass should not call
* {@link #createCollection()} directly, and a new instance should be created
* every time the method is called.
*
* <p>For example, the subclass could pass a {@link java.util.TreeMap} during
* construction, and {@link #createCollection()} could return a {@link
* java.util.TreeSet}, in which case the multimap's iterators would propagate
* through the keys and values in sorted order.
*
* <p>Keys and values may be null, as long as the underlying collection classes
* support null elements.
*
* <p>The collections created by {@link #createCollection()} may or may not
* allow duplicates. If the collection, such as a {@link Set}, does not support
* duplicates, an added key-value pair will replace an existing pair with the
* same key and value, if such a pair is present. With collections like {@link
* List} that allow duplicates, the collection will keep the existing key-value
* pairs while adding a new pair.
*
* <p>This class is not threadsafe when any concurrent operations update the
* multimap, even if the underlying map and {@link #createCollection()} method
* return threadsafe classes. Concurrent read operations will work correctly. To
* allow concurrent update operations, wrap your multimap with a call to {@link
* Multimaps#synchronizedMultimap}.
*
* <p>For serialization to work, the subclass must specify explicit
* {@code readObject} and {@code writeObject} methods.
*
* @author Jared Levy
* @author Louis Wasserman
*/
@GwtCompatible
abstract class AbstractMultimap<K, V> implements Multimap<K, V>, Serializable {
/*
* Here's an outline of the overall design.
*
* The map variable contains the collection of values associated with each
* key. When a key-value pair is added to a multimap that didn't previously
* contain any values for that key, a new collection generated by
* createCollection is added to the map. That same collection instance
* remains in the map as long as the multimap has any values for the key. If
* all values for the key are removed, the key and collection are removed
* from the map.
*
* The get method returns a WrappedCollection, which decorates the collection
* in the map (if the key is present) or an empty collection (if the key is
* not present). When the collection delegate in the WrappedCollection is
* empty, the multimap may contain subsequently added values for that key. To
* handle that situation, the WrappedCollection checks whether map contains
* an entry for the provided key, and if so replaces the delegate.
*/
private transient Map<K, Collection<V>> map;
private transient int totalSize;
/**
* Creates a new multimap that uses the provided map.
*
* @param map place to store the mapping from each key to its corresponding
* values
* @throws IllegalArgumentException if {@code map} is not empty
*/
protected AbstractMultimap(Map<K, Collection<V>> map) {
checkArgument(map.isEmpty());
this.map = map;
}
/** Used during deserialization only. */
final void setMap(Map<K, Collection<V>> map) {
this.map = map;
totalSize = 0;
for (Collection<V> values : map.values()) {
checkArgument(!values.isEmpty());
totalSize += values.size();
}
}
/**
* Creates the collection of values for a single key.
*
* <p>Collections with weak, soft, or phantom references are not supported.
* Each call to {@code createCollection} should create a new instance.
*
* <p>The returned collection class determines whether duplicate key-value
* pairs are allowed.
*
* @return an empty collection of values
*/
abstract Collection<V> createCollection();
/**
* Creates the collection of values for an explicitly provided key. By
* default, it simply calls {@link #createCollection()}, which is the correct
* behavior for most implementations. The {@link LinkedHashMultimap} class
* overrides it.
*
* @param key key to associate with values in the collection
* @return an empty collection of values
*/
Collection<V> createCollection(@Nullable K key) {
return createCollection();
}
Map<K, Collection<V>> backingMap() {
return map;
}
// Query Operations
@Override
public int size() {
return totalSize;
}
@Override
public boolean isEmpty() {
return totalSize == 0;
}
@Override
public boolean containsKey(@Nullable Object key) {
return map.containsKey(key);
}
@Override
public boolean containsValue(@Nullable Object value) {
for (Collection<V> collection : map.values()) {
if (collection.contains(value)) {
return true;
}
}
return false;
}
@Override
public boolean containsEntry(@Nullable Object key, @Nullable Object value) {
Collection<V> collection = map.get(key);
return collection != null && collection.contains(value);
}
// Modification Operations
@Override
public boolean put(@Nullable K key, @Nullable V value) {
Collection<V> collection = getOrCreateCollection(key);
if (collection.add(value)) {
totalSize++;
return true;
} else {
return false;
}
}
private Collection<V> getOrCreateCollection(@Nullable K key) {
Collection<V> collection = map.get(key);
if (collection == null) {
collection = createCollection(key);
map.put(key, collection);
}
return collection;
}
@Override
public boolean remove(@Nullable Object key, @Nullable Object value) {
Collection<V> collection = map.get(key);
if (collection == null) {
return false;
}
boolean changed = collection.remove(value);
if (changed) {
totalSize--;
if (collection.isEmpty()) {
map.remove(key);
}
}
return changed;
}
// Bulk Operations
@Override
public boolean putAll(@Nullable K key, Iterable<? extends V> values) {
if (!values.iterator().hasNext()) {
return false;
}
Collection<V> collection = getOrCreateCollection(key);
int oldSize = collection.size();
boolean changed = false;
if (values instanceof Collection) {
Collection<? extends V> c = Collections2.cast(values);
changed = collection.addAll(c);
} else {
for (V value : values) {
changed |= collection.add(value);
}
}
totalSize += (collection.size() - oldSize);
return changed;
}
@Override
public boolean putAll(Multimap<? extends K, ? extends V> multimap) {
boolean changed = false;
for (Map.Entry<? extends K, ? extends V> entry : multimap.entries()) {
changed |= put(entry.getKey(), entry.getValue());
}
return changed;
}
/**
* {@inheritDoc}
*
* <p>The returned collection is immutable.
*/
@Override
public Collection<V> replaceValues(
@Nullable K key, Iterable<? extends V> values) {
Iterator<? extends V> iterator = values.iterator();
if (!iterator.hasNext()) {
return removeAll(key);
}
Collection<V> collection = getOrCreateCollection(key);
Collection<V> oldValues = createCollection();
oldValues.addAll(collection);
totalSize -= collection.size();
collection.clear();
while (iterator.hasNext()) {
if (collection.add(iterator.next())) {
totalSize++;
}
}
return unmodifiableCollectionSubclass(oldValues);
}
/**
* {@inheritDoc}
*
* <p>The returned collection is immutable.
*/
@Override
public Collection<V> removeAll(@Nullable Object key) {
Collection<V> collection = map.remove(key);
Collection<V> output = createCollection();
if (collection != null) {
output.addAll(collection);
totalSize -= collection.size();
collection.clear();
}
return unmodifiableCollectionSubclass(output);
}
private Collection<V> unmodifiableCollectionSubclass(
Collection<V> collection) {
if (collection instanceof SortedSet) {
return Collections.unmodifiableSortedSet((SortedSet<V>) collection);
} else if (collection instanceof Set) {
return Collections.unmodifiableSet((Set<V>) collection);
} else if (collection instanceof List) {
return Collections.unmodifiableList((List<V>) collection);
} else {
return Collections.unmodifiableCollection(collection);
}
}
@Override
public void clear() {
// Clear each collection, to make previously returned collections empty.
for (Collection<V> collection : map.values()) {
collection.clear();
}
map.clear();
totalSize = 0;
}
// Views
/**
* {@inheritDoc}
*
* <p>The returned collection is not serializable.
*/
@Override
public Collection<V> get(@Nullable K key) {
Collection<V> collection = map.get(key);
if (collection == null) {
collection = createCollection(key);
}
return wrapCollection(key, collection);
}
/**
* Generates a decorated collection that remains consistent with the values in
* the multimap for the provided key. Changes to the multimap may alter the
* returned collection, and vice versa.
*/
private Collection<V> wrapCollection(
@Nullable K key, Collection<V> collection) {
if (collection instanceof SortedSet) {
return new WrappedSortedSet(key, (SortedSet<V>) collection, null);
} else if (collection instanceof Set) {
return new WrappedSet(key, (Set<V>) collection);
} else if (collection instanceof List) {
return wrapList(key, (List<V>) collection, null);
} else {
return new WrappedCollection(key, collection, null);
}
}
private List<V> wrapList(
@Nullable K key, List<V> list, @Nullable WrappedCollection ancestor) {
return (list instanceof RandomAccess)
? new RandomAccessWrappedList(key, list, ancestor)
: new WrappedList(key, list, ancestor);
}
/**
* Collection decorator that stays in sync with the multimap values for a key.
* There are two kinds of wrapped collections: full and subcollections. Both
* have a delegate pointing to the underlying collection class.
*
* <p>Full collections, identified by a null ancestor field, contain all
* multimap values for a given key. Its delegate is a value in {@link
* AbstractMultimap#map} whenever the delegate is non-empty. The {@code
* refreshIfEmpty}, {@code removeIfEmpty}, and {@code addToMap} methods ensure
* that the {@code WrappedCollection} and map remain consistent.
*
* <p>A subcollection, such as a sublist, contains some of the values for a
* given key. Its ancestor field points to the full wrapped collection with
* all values for the key. The subcollection {@code refreshIfEmpty}, {@code
* removeIfEmpty}, and {@code addToMap} methods call the corresponding methods
* of the full wrapped collection.
*/
private class WrappedCollection extends AbstractCollection<V> {
final K key;
Collection<V> delegate;
final WrappedCollection ancestor;
final Collection<V> ancestorDelegate;
WrappedCollection(@Nullable K key, Collection<V> delegate,
@Nullable WrappedCollection ancestor) {
this.key = key;
this.delegate = delegate;
this.ancestor = ancestor;
this.ancestorDelegate
= (ancestor == null) ? null : ancestor.getDelegate();
}
/**
* If the delegate collection is empty, but the multimap has values for the
* key, replace the delegate with the new collection for the key.
*
* <p>For a subcollection, refresh its ancestor and validate that the
* ancestor delegate hasn't changed.
*/
void refreshIfEmpty() {
if (ancestor != null) {
ancestor.refreshIfEmpty();
if (ancestor.getDelegate() != ancestorDelegate) {
throw new ConcurrentModificationException();
}
} else if (delegate.isEmpty()) {
Collection<V> newDelegate = map.get(key);
if (newDelegate != null) {
delegate = newDelegate;
}
}
}
/**
* If collection is empty, remove it from {@code AbstractMultimap.this.map}.
* For subcollections, check whether the ancestor collection is empty.
*/
void removeIfEmpty() {
if (ancestor != null) {
ancestor.removeIfEmpty();
} else if (delegate.isEmpty()) {
map.remove(key);
}
}
K getKey() {
return key;
}
/**
* Add the delegate to the map. Other {@code WrappedCollection} methods
* should call this method after adding elements to a previously empty
* collection.
*
* <p>Subcollection add the ancestor's delegate instead.
*/
void addToMap() {
if (ancestor != null) {
ancestor.addToMap();
} else {
map.put(key, delegate);
}
}
@Override public int size() {
refreshIfEmpty();
return delegate.size();
}
@Override public boolean equals(@Nullable Object object) {
if (object == this) {
return true;
}
refreshIfEmpty();
return delegate.equals(object);
}
@Override public int hashCode() {
refreshIfEmpty();
return delegate.hashCode();
}
@Override public String toString() {
refreshIfEmpty();
return delegate.toString();
}
Collection<V> getDelegate() {
return delegate;
}
@Override public Iterator<V> iterator() {
refreshIfEmpty();
return new WrappedIterator();
}
/** Collection iterator for {@code WrappedCollection}. */
class WrappedIterator implements Iterator<V> {
final Iterator<V> delegateIterator;
final Collection<V> originalDelegate = delegate;
WrappedIterator() {
delegateIterator = iteratorOrListIterator(delegate);
}
WrappedIterator(Iterator<V> delegateIterator) {
this.delegateIterator = delegateIterator;
}
/**
* If the delegate changed since the iterator was created, the iterator is
* no longer valid.
*/
void validateIterator() {
refreshIfEmpty();
if (delegate != originalDelegate) {
throw new ConcurrentModificationException();
}
}
@Override
public boolean hasNext() {
validateIterator();
return delegateIterator.hasNext();
}
@Override
public V next() {
validateIterator();
return delegateIterator.next();
}
@Override
public void remove() {
delegateIterator.remove();
totalSize--;
removeIfEmpty();
}
Iterator<V> getDelegateIterator() {
validateIterator();
return delegateIterator;
}
}
@Override public boolean add(V value) {
refreshIfEmpty();
boolean wasEmpty = delegate.isEmpty();
boolean changed = delegate.add(value);
if (changed) {
totalSize++;
if (wasEmpty) {
addToMap();
}
}
return changed;
}
WrappedCollection getAncestor() {
return ancestor;
}
// The following methods are provided for better performance.
@Override public boolean addAll(Collection<? extends V> collection) {
if (collection.isEmpty()) {
return false;
}
int oldSize = size(); // calls refreshIfEmpty
boolean changed = delegate.addAll(collection);
if (changed) {
int newSize = delegate.size();
totalSize += (newSize - oldSize);
if (oldSize == 0) {
addToMap();
}
}
return changed;
}
@Override public boolean contains(Object o) {
refreshIfEmpty();
return delegate.contains(o);
}
@Override public boolean containsAll(Collection<?> c) {
refreshIfEmpty();
return delegate.containsAll(c);
}
@Override public void clear() {
int oldSize = size(); // calls refreshIfEmpty
if (oldSize == 0) {
return;
}
delegate.clear();
totalSize -= oldSize;
removeIfEmpty(); // maybe shouldn't be removed if this is a sublist
}
@Override public boolean remove(Object o) {
refreshIfEmpty();
boolean changed = delegate.remove(o);
if (changed) {
totalSize--;
removeIfEmpty();
}
return changed;
}
@Override public boolean removeAll(Collection<?> c) {
if (c.isEmpty()) {
return false;
}
int oldSize = size(); // calls refreshIfEmpty
boolean changed = delegate.removeAll(c);
if (changed) {
int newSize = delegate.size();
totalSize += (newSize - oldSize);
removeIfEmpty();
}
return changed;
}
@Override public boolean retainAll(Collection<?> c) {
checkNotNull(c);
int oldSize = size(); // calls refreshIfEmpty
boolean changed = delegate.retainAll(c);
if (changed) {
int newSize = delegate.size();
totalSize += (newSize - oldSize);
removeIfEmpty();
}
return changed;
}
}
private Iterator<V> iteratorOrListIterator(Collection<V> collection) {
return (collection instanceof List)
? ((List<V>) collection).listIterator()
: collection.iterator();
}
/** Set decorator that stays in sync with the multimap values for a key. */
private class WrappedSet extends WrappedCollection implements Set<V> {
WrappedSet(@Nullable K key, Set<V> delegate) {
super(key, delegate, null);
}
}
/**
* SortedSet decorator that stays in sync with the multimap values for a key.
*/
private class WrappedSortedSet extends WrappedCollection
implements SortedSet<V> {
WrappedSortedSet(@Nullable K key, SortedSet<V> delegate,
@Nullable WrappedCollection ancestor) {
super(key, delegate, ancestor);
}
SortedSet<V> getSortedSetDelegate() {
return (SortedSet<V>) getDelegate();
}
@Override
public Comparator<? super V> comparator() {
return getSortedSetDelegate().comparator();
}
@Override
public V first() {
refreshIfEmpty();
return getSortedSetDelegate().first();
}
@Override
public V last() {
refreshIfEmpty();
return getSortedSetDelegate().last();
}
@Override
public SortedSet<V> headSet(V toElement) {
refreshIfEmpty();
return new WrappedSortedSet(
getKey(), getSortedSetDelegate().headSet(toElement),
(getAncestor() == null) ? this : getAncestor());
}
@Override
public SortedSet<V> subSet(V fromElement, V toElement) {
refreshIfEmpty();
return new WrappedSortedSet(
getKey(), getSortedSetDelegate().subSet(fromElement, toElement),
(getAncestor() == null) ? this : getAncestor());
}
@Override
public SortedSet<V> tailSet(V fromElement) {
refreshIfEmpty();
return new WrappedSortedSet(
getKey(), getSortedSetDelegate().tailSet(fromElement),
(getAncestor() == null) ? this : getAncestor());
}
}
/** List decorator that stays in sync with the multimap values for a key. */
private class WrappedList extends WrappedCollection implements List<V> {
WrappedList(@Nullable K key, List<V> delegate,
@Nullable WrappedCollection ancestor) {
super(key, delegate, ancestor);
}
List<V> getListDelegate() {
return (List<V>) getDelegate();
}
@Override
public boolean addAll(int index, Collection<? extends V> c) {
if (c.isEmpty()) {
return false;
}
int oldSize = size(); // calls refreshIfEmpty
boolean changed = getListDelegate().addAll(index, c);
if (changed) {
int newSize = getDelegate().size();
totalSize += (newSize - oldSize);
if (oldSize == 0) {
addToMap();
}
}
return changed;
}
@Override
public V get(int index) {
refreshIfEmpty();
return getListDelegate().get(index);
}
@Override
public V set(int index, V element) {
refreshIfEmpty();
return getListDelegate().set(index, element);
}
@Override
public void add(int index, V element) {
refreshIfEmpty();
boolean wasEmpty = getDelegate().isEmpty();
getListDelegate().add(index, element);
totalSize++;
if (wasEmpty) {
addToMap();
}
}
@Override
public V remove(int index) {
refreshIfEmpty();
V value = getListDelegate().remove(index);
totalSize--;
removeIfEmpty();
return value;
}
@Override
public int indexOf(Object o) {
refreshIfEmpty();
return getListDelegate().indexOf(o);
}
@Override
public int lastIndexOf(Object o) {
refreshIfEmpty();
return getListDelegate().lastIndexOf(o);
}
@Override
public ListIterator<V> listIterator() {
refreshIfEmpty();
return new WrappedListIterator();
}
@Override
public ListIterator<V> listIterator(int index) {
refreshIfEmpty();
return new WrappedListIterator(index);
}
@Override
public List<V> subList(int fromIndex, int toIndex) {
refreshIfEmpty();
return wrapList(getKey(),
getListDelegate().subList(fromIndex, toIndex),
(getAncestor() == null) ? this : getAncestor());
}
/** ListIterator decorator. */
private class WrappedListIterator extends WrappedIterator
implements ListIterator<V> {
WrappedListIterator() {}
public WrappedListIterator(int index) {
super(getListDelegate().listIterator(index));
}
private ListIterator<V> getDelegateListIterator() {
return (ListIterator<V>) getDelegateIterator();
}
@Override
public boolean hasPrevious() {
return getDelegateListIterator().hasPrevious();
}
@Override
public V previous() {
return getDelegateListIterator().previous();
}
@Override
public int nextIndex() {
return getDelegateListIterator().nextIndex();
}
@Override
public int previousIndex() {
return getDelegateListIterator().previousIndex();
}
@Override
public void set(V value) {
getDelegateListIterator().set(value);
}
@Override
public void add(V value) {
boolean wasEmpty = isEmpty();
getDelegateListIterator().add(value);
totalSize++;
if (wasEmpty) {
addToMap();
}
}
}
}
/**
* List decorator that stays in sync with the multimap values for a key and
* supports rapid random access.
*/
private class RandomAccessWrappedList extends WrappedList
implements RandomAccess {
RandomAccessWrappedList(@Nullable K key, List<V> delegate,
@Nullable WrappedCollection ancestor) {
super(key, delegate, ancestor);
}
}
private transient Set<K> keySet;
@Override
public Set<K> keySet() {
Set<K> result = keySet;
return (result == null) ? keySet = createKeySet() : result;
}
private Set<K> createKeySet() {
return (map instanceof SortedMap)
? new SortedKeySet((SortedMap<K, Collection<V>>) map) : new KeySet(map);
}
private class KeySet extends Maps.KeySet<K, Collection<V>> {
/**
* This is usually the same as map, except when someone requests a
* subcollection of a {@link SortedKeySet}.
*/
final Map<K, Collection<V>> subMap;
KeySet(final Map<K, Collection<V>> subMap) {
this.subMap = subMap;
}
@Override
Map<K, Collection<V>> map() {
return subMap;
}
@Override public Iterator<K> iterator() {
return new Iterator<K>() {
final Iterator<Map.Entry<K, Collection<V>>> entryIterator
= subMap.entrySet().iterator();
Map.Entry<K, Collection<V>> entry;
@Override
public boolean hasNext() {
return entryIterator.hasNext();
}
@Override
public K next() {
entry = entryIterator.next();
return entry.getKey();
}
@Override
public void remove() {
checkState(entry != null);
Collection<V> collection = entry.getValue();
entryIterator.remove();
totalSize -= collection.size();
collection.clear();
}
};
}
// The following methods are included for better performance.
@Override public boolean remove(Object key) {
int count = 0;
Collection<V> collection = subMap.remove(key);
if (collection != null) {
count = collection.size();
collection.clear();
totalSize -= count;
}
return count > 0;
}
@Override
public void clear() {
Iterators.clear(iterator());
}
@Override public boolean containsAll(Collection<?> c) {
return subMap.keySet().containsAll(c);
}
@Override public boolean equals(@Nullable Object object) {
return this == object || this.subMap.keySet().equals(object);
}
@Override public int hashCode() {
return subMap.keySet().hashCode();
}
}
private class SortedKeySet extends KeySet implements SortedSet<K> {
SortedKeySet(SortedMap<K, Collection<V>> subMap) {
super(subMap);
}
SortedMap<K, Collection<V>> sortedMap() {
return (SortedMap<K, Collection<V>>) subMap;
}
@Override
public Comparator<? super K> comparator() {
return sortedMap().comparator();
}
@Override
public K first() {
return sortedMap().firstKey();
}
@Override
public SortedSet<K> headSet(K toElement) {
return new SortedKeySet(sortedMap().headMap(toElement));
}
@Override
public K last() {
return sortedMap().lastKey();
}
@Override
public SortedSet<K> subSet(K fromElement, K toElement) {
return new SortedKeySet(sortedMap().subMap(fromElement, toElement));
}
@Override
public SortedSet<K> tailSet(K fromElement) {
return new SortedKeySet(sortedMap().tailMap(fromElement));
}
}
private transient Multiset<K> multiset;
@Override
public Multiset<K> keys() {
Multiset<K> result = multiset;
if (result == null) {
return multiset = new Multimaps.Keys<K, V>() {
@Override Multimap<K, V> multimap() {
return AbstractMultimap.this;
}
};
}
return result;
}
/**
* Removes all values for the provided key. Unlike {@link #removeAll}, it
* returns the number of removed mappings.
*/
private int removeValuesForKey(Object key) {
Collection<V> collection;
try {
collection = map.remove(key);
} catch (NullPointerException e) {
return 0;
} catch (ClassCastException e) {
return 0;
}
int count = 0;
if (collection != null) {
count = collection.size();
collection.clear();
totalSize -= count;
}
return count;
}
private transient Collection<V> valuesCollection;
/**
* {@inheritDoc}
*
* <p>The iterator generated by the returned collection traverses the values
* for one key, followed by the values of a second key, and so on.
*/
@Override public Collection<V> values() {
Collection<V> result = valuesCollection;
if (result == null) {
return valuesCollection = new Multimaps.Values<K, V>() {
@Override Multimap<K, V> multimap() {
return AbstractMultimap.this;
}
};
}
return result;
}
private transient Collection<Map.Entry<K, V>> entries;
/*
* TODO(kevinb): should we copy this javadoc to each concrete class, so that
* classes like LinkedHashMultimap that need to say something different are
* still able to {@inheritDoc} all the way from Multimap?
*/
/**
* {@inheritDoc}
*
* <p>The iterator generated by the returned collection traverses the values
* for one key, followed by the values of a second key, and so on.
*
* <p>Each entry is an immutable snapshot of a key-value mapping in the
* multimap, taken at the time the entry is returned by a method call to the
* collection or its iterator.
*/
@Override
public Collection<Map.Entry<K, V>> entries() {
Collection<Map.Entry<K, V>> result = entries;
return (result == null) ? entries = createEntries() : result;
}
Collection<Map.Entry<K, V>> createEntries() {
if (this instanceof SetMultimap) {
return new Multimaps.EntrySet<K, V>() {
@Override Multimap<K, V> multimap() {
return AbstractMultimap.this;
}
@Override public Iterator<Entry<K, V>> iterator() {
return createEntryIterator();
}
};
}
return new Multimaps.Entries<K, V>() {
@Override Multimap<K, V> multimap() {
return AbstractMultimap.this;
}
@Override public Iterator<Entry<K, V>> iterator() {
return createEntryIterator();
}
};
}
/**
* Returns an iterator across all key-value map entries, used by {@code
* entries().iterator()} and {@code values().iterator()}. The default
* behavior, which traverses the values for one key, the values for a second
* key, and so on, suffices for most {@code AbstractMultimap} implementations.
*
* @return an iterator across map entries
*/
Iterator<Map.Entry<K, V>> createEntryIterator() {
return new EntryIterator();
}
/** Iterator across all key-value pairs. */
private class EntryIterator implements Iterator<Map.Entry<K, V>> {
final Iterator<Map.Entry<K, Collection<V>>> keyIterator;
K key;
Collection<V> collection;
Iterator<V> valueIterator;
EntryIterator() {
keyIterator = map.entrySet().iterator();
if (keyIterator.hasNext()) {
findValueIteratorAndKey();
} else {
valueIterator = Iterators.emptyModifiableIterator();
}
}
void findValueIteratorAndKey() {
Map.Entry<K, Collection<V>> entry = keyIterator.next();
key = entry.getKey();
collection = entry.getValue();
valueIterator = collection.iterator();
}
@Override
public boolean hasNext() {
return keyIterator.hasNext() || valueIterator.hasNext();
}
@Override
public Map.Entry<K, V> next() {
if (!valueIterator.hasNext()) {
findValueIteratorAndKey();
}
return Maps.immutableEntry(key, valueIterator.next());
}
@Override
public void remove() {
valueIterator.remove();
if (collection.isEmpty()) {
keyIterator.remove();
}
totalSize--;
}
}
private transient Map<K, Collection<V>> asMap;
@Override
public Map<K, Collection<V>> asMap() {
Map<K, Collection<V>> result = asMap;
return (result == null) ? asMap = createAsMap() : result;
}
private Map<K, Collection<V>> createAsMap() {
return (map instanceof SortedMap)
? new SortedAsMap((SortedMap<K, Collection<V>>) map) : new AsMap(map);
}
private class AsMap extends AbstractMap<K, Collection<V>> {
/**
* Usually the same as map, but smaller for the headMap(), tailMap(), or
* subMap() of a SortedAsMap.
*/
final transient Map<K, Collection<V>> submap;
AsMap(Map<K, Collection<V>> submap) {
this.submap = submap;
}
transient Set<Map.Entry<K, Collection<V>>> entrySet;
@Override public Set<Map.Entry<K, Collection<V>>> entrySet() {
Set<Map.Entry<K, Collection<V>>> result = entrySet;
return (result == null) ? entrySet = new AsMapEntries() : result;
}
// The following methods are included for performance.
@Override public boolean containsKey(Object key) {
return Maps.safeContainsKey(submap, key);
}
@Override public Collection<V> get(Object key) {
Collection<V> collection = Maps.safeGet(submap, key);
if (collection == null) {
return null;
}
@SuppressWarnings("unchecked")
K k = (K) key;
return wrapCollection(k, collection);
}
@Override public Set<K> keySet() {
return AbstractMultimap.this.keySet();
}
@Override
public int size() {
return submap.size();
}
@Override public Collection<V> remove(Object key) {
Collection<V> collection = submap.remove(key);
if (collection == null) {
return null;
}
Collection<V> output = createCollection();
output.addAll(collection);
totalSize -= collection.size();
collection.clear();
return output;
}
@Override public boolean equals(@Nullable Object object) {
return this == object || submap.equals(object);
}
@Override public int hashCode() {
return submap.hashCode();
}
@Override public String toString() {
return submap.toString();
}
@Override
public void clear() {
if (submap == map) {
AbstractMultimap.this.clear();
} else {
Iterators.clear(new AsMapIterator());
}
}
class AsMapEntries extends Maps.EntrySet<K, Collection<V>> {
@Override
Map<K, Collection<V>> map() {
return AsMap.this;
}
@Override public Iterator<Map.Entry<K, Collection<V>>> iterator() {
return new AsMapIterator();
}
// The following methods are included for performance.
@Override public boolean contains(Object o) {
return Collections2.safeContains(submap.entrySet(), o);
}
@Override public boolean remove(Object o) {
if (!contains(o)) {
return false;
}
Map.Entry<?, ?> entry = (Map.Entry<?, ?>) o;
removeValuesForKey(entry.getKey());
return true;
}
}
/** Iterator across all keys and value collections. */
class AsMapIterator implements Iterator<Map.Entry<K, Collection<V>>> {
final Iterator<Map.Entry<K, Collection<V>>> delegateIterator
= submap.entrySet().iterator();
Collection<V> collection;
@Override
public boolean hasNext() {
return delegateIterator.hasNext();
}
@Override
public Map.Entry<K, Collection<V>> next() {
Map.Entry<K, Collection<V>> entry = delegateIterator.next();
K key = entry.getKey();
collection = entry.getValue();
return Maps.immutableEntry(key, wrapCollection(key, collection));
}
@Override
public void remove() {
delegateIterator.remove();
totalSize -= collection.size();
collection.clear();
}
}
}
private class SortedAsMap extends AsMap
implements SortedMap<K, Collection<V>> {
SortedAsMap(SortedMap<K, Collection<V>> submap) {
super(submap);
}
SortedMap<K, Collection<V>> sortedMap() {
return (SortedMap<K, Collection<V>>) submap;
}
@Override
public Comparator<? super K> comparator() {
return sortedMap().comparator();
}
@Override
public K firstKey() {
return sortedMap().firstKey();
}
@Override
public K lastKey() {
return sortedMap().lastKey();
}
@Override
public SortedMap<K, Collection<V>> headMap(K toKey) {
return new SortedAsMap(sortedMap().headMap(toKey));
}
@Override
public SortedMap<K, Collection<V>> subMap(K fromKey, K toKey) {
return new SortedAsMap(sortedMap().subMap(fromKey, toKey));
}
@Override
public SortedMap<K, Collection<V>> tailMap(K fromKey) {
return new SortedAsMap(sortedMap().tailMap(fromKey));
}
SortedSet<K> sortedKeySet;
// returns a SortedSet, even though returning a Set would be sufficient to
// satisfy the SortedMap.keySet() interface
@Override public SortedSet<K> keySet() {
SortedSet<K> result = sortedKeySet;
return (result == null)
? sortedKeySet = new SortedKeySet(sortedMap()) : result;
}
}
// Comparison and hashing
@Override public boolean equals(@Nullable Object object) {
if (object == this) {
return true;
}
if (object instanceof Multimap) {
Multimap<?, ?> that = (Multimap<?, ?>) object;
return this.map.equals(that.asMap());
}
return false;
}
/**
* Returns the hash code for this multimap.
*
* <p>The hash code of a multimap is defined as the hash code of the map view,
* as returned by {@link Multimap#asMap}.
*
* @see Map#hashCode
*/
@Override public int hashCode() {
return map.hashCode();
}
/**
* Returns a string representation of the multimap, generated by calling
* {@code toString} on the map returned by {@link Multimap#asMap}.
*
* @return a string representation of the multimap
*/
@Override
public String toString() {
return map.toString();
}
private static final long serialVersionUID = 2447537837011683357L;
}
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