com.google.common.collect.AbstractMultimap Maven / Gradle / Ivy
/*
* 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.AbstractCollection;
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 implements Multimap {
@Override
public boolean isEmpty() {
return size() == 0;
}
@Override
public boolean containsValue(@Nullable Object value) {
for (Collection collection : asMap().values()) {
if (collection.contains(value)) {
return true;
}
}
return false;
}
@Override
public boolean containsEntry(@Nullable Object key, @Nullable Object value) {
Collection collection = asMap().get(key);
return collection != null && collection.contains(value);
}
@Override
public boolean remove(@Nullable Object key, @Nullable Object value) {
Collection 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 values) {
checkNotNull(values);
// make sure we only call values.iterator() once
// and we only call get(key) if values is nonempty
if (values instanceof Collection) {
Collection valueCollection = (Collection) values;
return !valueCollection.isEmpty() && get(key).addAll(valueCollection);
} else {
Iterator valueItr = values.iterator();
return valueItr.hasNext() && Iterators.addAll(get(key), valueItr);
}
}
@Override
public boolean putAll(Multimap multimap) {
boolean changed = false;
for (Map.Entry entry : multimap.entries()) {
changed |= put(entry.getKey(), entry.getValue());
}
return changed;
}
@Override
public Collection replaceValues(@Nullable K key, Iterable values) {
checkNotNull(values);
Collection result = removeAll(key);
putAll(key, values);
return result;
}
private transient Collection> entries;
@Override
public Collection> entries() {
Collection> result = entries;
return (result == null) ? entries = createEntries() : result;
}
Collection> createEntries() {
if (this instanceof SetMultimap) {
return new EntrySet();
} else {
return new Entries();
}
}
private class Entries extends Multimaps.Entries {
@Override
Multimap multimap() {
return AbstractMultimap.this;
}
@Override
public Iterator> iterator() {
return entryIterator();
}
}
private class EntrySet extends Entries implements Set> {
@Override
public int hashCode() {
return Sets.hashCodeImpl(this);
}
@Override
public boolean equals(@Nullable Object obj) {
return Sets.equalsImpl(this, obj);
}
}
abstract Iterator> entryIterator();
private transient Set keySet;
@Override
public Set keySet() {
Set result = keySet;
return (result == null) ? keySet = createKeySet() : result;
}
Set createKeySet() {
return new Maps.KeySet>(asMap());
}
private transient Multiset keys;
@Override
public Multiset keys() {
Multiset result = keys;
return (result == null) ? keys = createKeys() : result;
}
Multiset createKeys() {
return new Multimaps.Keys(this);
}
private transient Collection values;
@Override
public Collection values() {
Collection result = values;
return (result == null) ? values = createValues() : result;
}
Collection createValues() {
return new Values();
}
class Values extends AbstractCollection {
@Override public Iterator iterator() {
return valueIterator();
}
@Override public int size() {
return AbstractMultimap.this.size();
}
@Override public boolean contains(@Nullable Object o) {
return AbstractMultimap.this.containsValue(o);
}
@Override public void clear() {
AbstractMultimap.this.clear();
}
}
Iterator valueIterator() {
return Maps.valueIterator(entries().iterator());
}
private transient Map> asMap;
@Override
public Map> asMap() {
Map> result = asMap;
return (result == null) ? asMap = createAsMap() : result;
}
abstract Map> createAsMap();
// Comparison and hashing
@Override public boolean equals(@Nullable Object object) {
return Multimaps.equalsImpl(this, object);
}
/**
* Returns the hash code for this multimap.
*
* 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();
}
}