TreeMultimap.java
/*
* 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.checkNotNull;
import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.Collection;
import java.util.Comparator;
import java.util.Map;
import java.util.NavigableMap;
import java.util.NavigableSet;
import java.util.SortedSet;
import java.util.TreeMap;
import java.util.TreeSet;
import org.checkerframework.checker.nullness.qual.Nullable;
/**
* Implementation of {@code Multimap} whose keys and values are ordered by their natural ordering or
* by supplied comparators. In all cases, this implementation uses {@link Comparable#compareTo} or
* {@link Comparator#compare} instead of {@link Object#equals} to determine equivalence of
* instances.
*
* <p><b>Warning:</b> The comparators or comparables used must be <i>consistent with equals</i> as
* explained by the {@link Comparable} class specification. Otherwise, the resulting multiset will
* violate the general contract of {@link SetMultimap}, which is specified in terms of {@link
* Object#equals}.
*
* <p>The collections returned by {@code keySet} and {@code asMap} iterate through the keys
* according to the key comparator ordering or the natural ordering of the keys. Similarly, {@code
* get}, {@code removeAll}, and {@code replaceValues} return collections that iterate through the
* values according to the value comparator ordering or the natural ordering of the values. The
* collections generated by {@code entries}, {@code keys}, and {@code values} iterate across the
* keys according to the above key ordering, and for each key they iterate across the values
* according to the value ordering.
*
* <p>The multimap does not store duplicate key-value pairs. Adding a new key-value pair equal to an
* existing key-value pair has no effect.
*
* <p>Null keys and values are permitted (provided, of course, that the respective comparators
* support them). All optional multimap methods are supported, and all returned views are
* modifiable.
*
* <p>This class is not threadsafe when any concurrent operations update the multimap. Concurrent
* read operations will work correctly. To allow concurrent update operations, wrap your multimap
* with a call to {@link Multimaps#synchronizedSortedSetMultimap}.
*
* <p>See the Guava User Guide article on <a href=
* "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multimap"> {@code
* Multimap}</a>.
*
* @author Jared Levy
* @author Louis Wasserman
* @since 2.0
*/
@GwtCompatible(serializable = true, emulated = true)
public class TreeMultimap<K, V> extends AbstractSortedKeySortedSetMultimap<K, V> {
private transient Comparator<? super K> keyComparator;
private transient Comparator<? super V> valueComparator;
/**
* Creates an empty {@code TreeMultimap} ordered by the natural ordering of its keys and values.
*/
public static <K extends Comparable, V extends Comparable> TreeMultimap<K, V> create() {
return new TreeMultimap<>(Ordering.natural(), Ordering.natural());
}
/**
* Creates an empty {@code TreeMultimap} instance using explicit comparators. Neither comparator
* may be null; use {@link Ordering#natural()} to specify natural order.
*
* @param keyComparator the comparator that determines the key ordering
* @param valueComparator the comparator that determines the value ordering
*/
public static <K, V> TreeMultimap<K, V> create(
Comparator<? super K> keyComparator, Comparator<? super V> valueComparator) {
return new TreeMultimap<>(checkNotNull(keyComparator), checkNotNull(valueComparator));
}
/**
* Constructs a {@code TreeMultimap}, ordered by the natural ordering of its keys and values, with
* the same mappings as the specified multimap.
*
* @param multimap the multimap whose contents are copied to this multimap
*/
public static <K extends Comparable, V extends Comparable> TreeMultimap<K, V> create(
Multimap<? extends K, ? extends V> multimap) {
return new TreeMultimap<>(Ordering.natural(), Ordering.natural(), multimap);
}
TreeMultimap(Comparator<? super K> keyComparator, Comparator<? super V> valueComparator) {
super(new TreeMap<K, Collection<V>>(keyComparator));
this.keyComparator = keyComparator;
this.valueComparator = valueComparator;
}
private TreeMultimap(
Comparator<? super K> keyComparator,
Comparator<? super V> valueComparator,
Multimap<? extends K, ? extends V> multimap) {
this(keyComparator, valueComparator);
putAll(multimap);
}
@Override
Map<K, Collection<V>> createAsMap() {
return createMaybeNavigableAsMap();
}
/**
* {@inheritDoc}
*
* <p>Creates an empty {@code TreeSet} for a collection of values for one key.
*
* @return a new {@code TreeSet} containing a collection of values for one key
*/
@Override
SortedSet<V> createCollection() {
return new TreeSet<V>(valueComparator);
}
@Override
Collection<V> createCollection(@Nullable K key) {
if (key == null) {
keyComparator().compare(key, key);
}
return super.createCollection(key);
}
/**
* Returns the comparator that orders the multimap keys.
*
* @deprecated Use {@code ((NavigableSet<K>) multimap.keySet()).comparator()} instead.
*/
@Deprecated
public Comparator<? super K> keyComparator() {
return keyComparator;
}
@Override
public Comparator<? super V> valueComparator() {
return valueComparator;
}
/** @since 14.0 (present with return type {@code SortedSet} since 2.0) */
@Override
@GwtIncompatible // NavigableSet
public NavigableSet<V> get(@Nullable K key) {
return (NavigableSet<V>) super.get(key);
}
/**
* {@inheritDoc}
*
* <p>Because a {@code TreeMultimap} has unique sorted keys, this method returns a {@link
* NavigableSet}, instead of the {@link java.util.Set} specified in the {@link Multimap}
* interface.
*
* @since 14.0 (present with return type {@code SortedSet} since 2.0)
*/
@Override
public NavigableSet<K> keySet() {
return (NavigableSet<K>) super.keySet();
}
/**
* {@inheritDoc}
*
* <p>Because a {@code TreeMultimap} has unique sorted keys, this method returns a {@link
* NavigableMap}, instead of the {@link java.util.Map} specified in the {@link Multimap}
* interface.
*
* @since 14.0 (present with return type {@code SortedMap} since 2.0)
*/
@Override
public NavigableMap<K, Collection<V>> asMap() {
return (NavigableMap<K, Collection<V>>) super.asMap();
}
/**
* @serialData key comparator, value comparator, number of distinct keys, and then for each
* distinct key: the key, number of values for that key, and key values
*/
@GwtIncompatible // java.io.ObjectOutputStream
private void writeObject(ObjectOutputStream stream) throws IOException {
stream.defaultWriteObject();
stream.writeObject(keyComparator());
stream.writeObject(valueComparator());
Serialization.writeMultimap(this, stream);
}
@GwtIncompatible // java.io.ObjectInputStream
@SuppressWarnings("unchecked") // reading data stored by writeObject
private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException {
stream.defaultReadObject();
keyComparator = checkNotNull((Comparator<? super K>) stream.readObject());
valueComparator = checkNotNull((Comparator<? super V>) stream.readObject());
setMap(new TreeMap<K, Collection<V>>(keyComparator));
Serialization.populateMultimap(this, stream);
}
@GwtIncompatible // not needed in emulated source
private static final long serialVersionUID = 0;
}