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/*
* 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 com.google.common.annotations.GwtCompatible;
import java.util.Collection;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import javax.annotation.Nullable;
/**
* A skeleton {@code Multimap} implementation, not necessarily in terms of a {@code Map}.
*
* @author Louis Wasserman
*/
@GwtCompatible
abstract class AbstractMultimap<K, V> implements Multimap<K, V> {
@Override
public boolean isEmpty() {
return size() == 0;
}
@Override
public boolean containsValue(@Nullable Object value) {
for (Collection<V> collection : asMap().values()) {
if (collection.contains(value)) {
return true;
}
}
return false;
}
@Override
public boolean containsEntry(@Nullable Object key, @Nullable Object value) {
Collection<V> collection = asMap().get(key);
return collection != null && collection.contains(value);
}
@Override
public boolean remove(@Nullable Object key, @Nullable Object value) {
Collection<V> collection = asMap().get(key);
return collection != null && collection.remove(value);
}
@Override
public boolean put(@Nullable K key, @Nullable V value) {
return get(key).add(value);
}
@Override
public boolean putAll(@Nullable K key, Iterable<? extends V> values) {
checkNotNull(values);
return values.iterator().hasNext() && Iterables.addAll(get(key), values);
}
@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;
}
@Override
public Collection<V> replaceValues(@Nullable K key, Iterable<? extends V> values) {
checkNotNull(values);
Collection<V> result = removeAll(key);
putAll(key, values);
return result;
}
private transient Collection<Entry<K, V>> entries;
@Override
public Collection<Entry<K, V>> entries() {
Collection<Entry<K, V>> result = entries;
return (result == null) ? entries = createEntries() : result;
}
Collection<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 entryIterator();
}
};
}
return new Multimaps.Entries<K, V>() {
@Override
Multimap<K, V> multimap() {
return AbstractMultimap.this;
}
@Override
public Iterator<Entry<K, V>> iterator() {
return entryIterator();
}
};
}
abstract Iterator<Entry<K, V>> entryIterator();
private transient Set<K> keySet;
@Override
public Set<K> keySet() {
Set<K> result = keySet;
return (result == null) ? keySet = createKeySet() : result;
}
Set<K> createKeySet() {
return new Maps.KeySet<K, Collection<V>>() {
@Override
Map<K, Collection<V>> map() {
return asMap();
}
};
}
private transient Multiset<K> keys;
@Override
public Multiset<K> keys() {
Multiset<K> result = keys;
return (result == null) ? keys = createKeys() : result;
}
Multiset<K> createKeys() {
return new Multimaps.Keys<K, V>(this);
}
private transient Collection<V> values;
@Override
public Collection<V> values() {
Collection<V> result = values;
return (result == null) ? values = createValues() : result;
}
Collection<V> createValues() {
return new Multimaps.Values<K, V>(this);
}
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;
}
abstract Map<K, Collection<V>> createAsMap();
// 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.asMap().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 asMap().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 asMap().toString();
}
}
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