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Java example source code file (FilteredEntryMultimap.java)
This example Java source code file (FilteredEntryMultimap.java) is included in the alvinalexander.com
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The FilteredEntryMultimap.java Java example source code
/*
* Copyright (C) 2012 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.checkNotNull;
import static com.google.common.base.Predicates.in;
import static com.google.common.base.Predicates.not;
import static com.google.common.collect.CollectPreconditions.checkNonnegative;
import com.google.common.annotations.GwtCompatible;
import com.google.common.base.MoreObjects;
import com.google.common.base.Predicate;
import com.google.common.collect.Maps.ViewCachingAbstractMap;
import com.google.j2objc.annotations.WeakOuter;
import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import javax.annotation.Nullable;
/**
* Implementation of {@link Multimaps#filterEntries(Multimap, Predicate)}.
*
* @author Jared Levy
* @author Louis Wasserman
*/
@GwtCompatible
class FilteredEntryMultimap<K, V> extends AbstractMultimap implements FilteredMultimap {
final Multimap<K, V> unfiltered;
final Predicate<? super Entry predicate;
FilteredEntryMultimap(Multimap<K, V> unfiltered, Predicate> predicate) {
this.unfiltered = checkNotNull(unfiltered);
this.predicate = checkNotNull(predicate);
}
@Override
public Multimap<K, V> unfiltered() {
return unfiltered;
}
@Override
public Predicate<? super Entry entryPredicate() {
return predicate;
}
@Override
public int size() {
return entries().size();
}
private boolean satisfies(K key, V value) {
return predicate.apply(Maps.immutableEntry(key, value));
}
final class ValuePredicate implements Predicate<V> {
private final K key;
ValuePredicate(K key) {
this.key = key;
}
@Override
public boolean apply(@Nullable V value) {
return satisfies(key, value);
}
}
static <E> Collection filterCollection(
Collection<E> collection, Predicate predicate) {
if (collection instanceof Set) {
return Sets.filter((Set<E>) collection, predicate);
} else {
return Collections2.filter(collection, predicate);
}
}
@Override
public boolean containsKey(@Nullable Object key) {
return asMap().get(key) != null;
}
@Override
public Collection<V> removeAll(@Nullable Object key) {
return MoreObjects.firstNonNull(asMap().remove(key), unmodifiableEmptyCollection());
}
Collection<V> unmodifiableEmptyCollection() {
// These return false, rather than throwing a UOE, on remove calls.
return (unfiltered instanceof SetMultimap)
? Collections.<V>emptySet()
: Collections.<V>emptyList();
}
@Override
public void clear() {
entries().clear();
}
@Override
public Collection<V> get(final K key) {
return filterCollection(unfiltered.get(key), new ValuePredicate(key));
}
@Override
Collection<Entry createEntries() {
return filterCollection(unfiltered.entries(), predicate);
}
@Override
Collection<V> createValues() {
return new FilteredMultimapValues<K, V>(this);
}
@Override
Iterator<Entry entryIterator() {
throw new AssertionError("should never be called");
}
@Override
Map<K, Collection createAsMap() {
return new AsMap();
}
@Override
public Set<K> keySet() {
return asMap().keySet();
}
boolean removeEntriesIf(Predicate<? super Entry> predicate) {
Iterator<Entry> entryIterator = unfiltered.asMap().entrySet().iterator();
boolean changed = false;
while (entryIterator.hasNext()) {
Entry<K, Collection entry = entryIterator.next();
K key = entry.getKey();
Collection<V> collection = filterCollection(entry.getValue(), new ValuePredicate(key));
if (!collection.isEmpty() && predicate.apply(Maps.immutableEntry(key, collection))) {
if (collection.size() == entry.getValue().size()) {
entryIterator.remove();
} else {
collection.clear();
}
changed = true;
}
}
return changed;
}
@WeakOuter
class AsMap extends ViewCachingAbstractMap<K, Collection {
@Override
public boolean containsKey(@Nullable Object key) {
return get(key) != null;
}
@Override
public void clear() {
FilteredEntryMultimap.this.clear();
}
@Override
public Collection<V> get(@Nullable Object key) {
Collection<V> result = unfiltered.asMap().get(key);
if (result == null) {
return null;
}
@SuppressWarnings("unchecked") // key is equal to a K, if not a K itself
K k = (K) key;
result = filterCollection(result, new ValuePredicate(k));
return result.isEmpty() ? null : result;
}
@Override
public Collection<V> remove(@Nullable Object key) {
Collection<V> collection = unfiltered.asMap().get(key);
if (collection == null) {
return null;
}
@SuppressWarnings("unchecked") // it's definitely equal to a K
K k = (K) key;
List<V> result = Lists.newArrayList();
Iterator<V> itr = collection.iterator();
while (itr.hasNext()) {
V v = itr.next();
if (satisfies(k, v)) {
itr.remove();
result.add(v);
}
}
if (result.isEmpty()) {
return null;
} else if (unfiltered instanceof SetMultimap) {
return Collections.unmodifiableSet(Sets.newLinkedHashSet(result));
} else {
return Collections.unmodifiableList(result);
}
}
@Override
Set<K> createKeySet() {
@WeakOuter
class KeySetImpl extends Maps.KeySet<K, Collection {
KeySetImpl() {
super(AsMap.this);
}
@Override
public boolean removeAll(Collection<?> c) {
return removeEntriesIf(Maps.<K>keyPredicateOnEntries(in(c)));
}
@Override
public boolean retainAll(Collection<?> c) {
return removeEntriesIf(Maps.<K>keyPredicateOnEntries(not(in(c))));
}
@Override
public boolean remove(@Nullable Object o) {
return AsMap.this.remove(o) != null;
}
}
return new KeySetImpl();
}
@Override
Set<Entry> createEntrySet() {
@WeakOuter
class EntrySetImpl extends Maps.EntrySet<K, Collection {
@Override
Map<K, Collection map() {
return AsMap.this;
}
@Override
public Iterator<Entry> iterator() {
return new AbstractIterator<Entry>() {
final Iterator<Entry> backingIterator =
unfiltered.asMap().entrySet().iterator();
@Override
protected Entry<K, Collection computeNext() {
while (backingIterator.hasNext()) {
Entry<K, Collection entry = backingIterator.next();
K key = entry.getKey();
Collection<V> collection =
filterCollection(entry.getValue(), new ValuePredicate(key));
if (!collection.isEmpty()) {
return Maps.immutableEntry(key, collection);
}
}
return endOfData();
}
};
}
@Override
public boolean removeAll(Collection<?> c) {
return removeEntriesIf(in(c));
}
@Override
public boolean retainAll(Collection<?> c) {
return removeEntriesIf(not(in(c)));
}
@Override
public int size() {
return Iterators.size(iterator());
}
}
return new EntrySetImpl();
}
@Override
Collection<Collection createValues() {
@WeakOuter
class ValuesImpl extends Maps.Values<K, Collection {
ValuesImpl() {
super(AsMap.this);
}
@Override
public boolean remove(@Nullable Object o) {
if (o instanceof Collection) {
Collection<?> c = (Collection) o;
Iterator<Entry> entryIterator =
unfiltered.asMap().entrySet().iterator();
while (entryIterator.hasNext()) {
Entry<K, Collection entry = entryIterator.next();
K key = entry.getKey();
Collection<V> collection =
filterCollection(entry.getValue(), new ValuePredicate(key));
if (!collection.isEmpty() && c.equals(collection)) {
if (collection.size() == entry.getValue().size()) {
entryIterator.remove();
} else {
collection.clear();
}
return true;
}
}
}
return false;
}
@Override
public boolean removeAll(Collection<?> c) {
return removeEntriesIf(Maps.<CollectionvaluePredicateOnEntries(in(c)));
}
@Override
public boolean retainAll(Collection<?> c) {
return removeEntriesIf(Maps.<CollectionvaluePredicateOnEntries(not(in(c))));
}
}
return new ValuesImpl();
}
}
@Override
Multiset<K> createKeys() {
return new Keys();
}
@WeakOuter
class Keys extends Multimaps.Keys<K, V> {
Keys() {
super(FilteredEntryMultimap.this);
}
@Override
public int remove(@Nullable Object key, int occurrences) {
checkNonnegative(occurrences, "occurrences");
if (occurrences == 0) {
return count(key);
}
Collection<V> collection = unfiltered.asMap().get(key);
if (collection == null) {
return 0;
}
@SuppressWarnings("unchecked") // key is equal to a K, if not a K itself
K k = (K) key;
int oldCount = 0;
Iterator<V> itr = collection.iterator();
while (itr.hasNext()) {
V v = itr.next();
if (satisfies(k, v)) {
oldCount++;
if (oldCount <= occurrences) {
itr.remove();
}
}
}
return oldCount;
}
@Override
public Set<Multiset.Entry entrySet() {
return new Multisets.EntrySet<K>() {
@Override
Multiset<K> multiset() {
return Keys.this;
}
@Override
public Iterator<Multiset.Entry iterator() {
return Keys.this.entryIterator();
}
@Override
public int size() {
return FilteredEntryMultimap.this.keySet().size();
}
private boolean removeEntriesIf(final Predicate<? super Multiset.Entry predicate) {
return FilteredEntryMultimap.this
.removeEntriesIf(
new Predicate<Map.Entry>() {
@Override
public boolean apply(Map.Entry<K, Collection entry) {
return predicate.apply(
Multisets.immutableEntry(entry.getKey(), entry.getValue().size()));
}
});
}
@Override
public boolean removeAll(Collection<?> c) {
return removeEntriesIf(in(c));
}
@Override
public boolean retainAll(Collection<?> c) {
return removeEntriesIf(not(in(c)));
}
};
}
}
}
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