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.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 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 replaceValues(@Nullable K key, Iterable extends V> 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 Multimaps.EntrySet() {
@Override
Multimap multimap() {
return AbstractMultimap.this;
}
@Override
public Iterator> iterator() {
return entryIterator();
}
};
}
return new Multimaps.Entries() {
@Override
Multimap multimap() {
return AbstractMultimap.this;
}
@Override
public Iterator> iterator() {
return entryIterator();
}
};
}
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>() {
@Override
Map> map() {
return 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 Multimaps.Values(this);
}
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) {
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.
*
* 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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