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/*
* Copyright (C) 2007 Google Inc.
*
* 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 com.google.common.base.Nullable;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.Collection;
import java.util.Comparator;
import java.util.Set;
import java.util.SortedSet;
import java.util.TreeMap;
import java.util.TreeSet;
/**
* Implementation of {@code Multimap} whose keys and values are ordered by their
* natural ordering or by supplied comparators. When constructing a {@code
* TreeMultimap}, you may provide a {@link Comparator} for the keys, a {@code
* Comparator} for the values, both, or neither. If the keys or values lack an
* explicit {@code Comparator}, their natural ordering is used.
*
* 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.
*
*
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.
*
*
Depending on the comparators, null keys and values may or may not be
* supported. The natural ordering does not support nulls. All optional multimap
* methods are supported, and all returned views are modifiable.
*
*
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}.
*
* @author Jared Levy
*/
public final class TreeMultimap extends StandardSortedSetMultimap {
private transient Comparator keyComparator;
private transient Comparator valueComparator;
/**
* Constructs an empty {@code TreeMultimap} using the natural ordering of the
* key and value classes. The key and value classes must satisfy the {@link
* Comparable} interface.
*/
public TreeMultimap() {
this(null, null);
}
/**
* Constructs an empty {@code TreeMultimap} with explicit comparators.
*
* @param keyComparator the comparator that determines key ordering, or
* {@code null} for natural ordering
* @param valueComparator the comparator that determines value ordering, or
* {@code null} for natural ordering
*/
public TreeMultimap(@Nullable Comparator keyComparator,
@Nullable Comparator valueComparator) {
super((keyComparator == null)
? new TreeMap>()
: new TreeMap>(keyComparator));
this.keyComparator = keyComparator;
this.valueComparator = valueComparator;
}
/**
* Constructs a {@code TreeMultimap} with the same mappings as the specified
* multimap.
*
* If the supplied multimap is an instance of {@code TreeMultimap}, the
* supplied multimap's key comparator is copied to the new instance.
* Otherwise, the new multimap uses the natural ordering of the keys, and the
* key class must satisfy the {@link Comparable} interface.
*
*
If the supplied multimap is a {@link SortedSetMultimap}, the supplied
* multimap's value comparator is copied to the new instance. Otherwise, the
* new multimap uses the natural ordering of the values, and the value class
* must satisfy the {@link Comparable} interface.
*
* @param multimap the multimap whose contents are copied to this multimap
*/
@SuppressWarnings("unchecked")
public TreeMultimap(Multimap multimap) {
this((multimap instanceof TreeMultimap)
? ((TreeMultimap) multimap).keyComparator() : null,
(multimap instanceof SortedSetMultimap)
? ((SortedSetMultimap) multimap).valueComparator() : null,
multimap);
}
/**
* Constructs a {@code TreeMultimap} with explicit comparators and the same
* mappings as the specified multimap.
*
* @param keyComparator the comparator that determines key ordering, or
* {@code null} for natural ordering
* @param valueComparator the comparator that determines value ordering, or
* {@code null} for natural ordering
* @param multimap the multimap whose contents are copied to this multimap
*/
public TreeMultimap(@Nullable Comparator keyComparator,
@Nullable Comparator valueComparator,
Multimap multimap) {
this(keyComparator, valueComparator);
putAll(multimap);
}
/**
* {@inheritDoc}
*
* 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 createCollection() {
return (valueComparator == null)
? new TreeSet() : new TreeSet(valueComparator);
}
/**
* Returns the comparator that orders the multimap keys, with a {@code null}
* indicating that natural ordering is used.
*/
public Comparator keyComparator() {
return keyComparator;
}
public Comparator valueComparator() {
return valueComparator;
}
/**
* {@inheritDoc}
*
* Because a {@code TreeMultimap} has unique sorted keys, this method
* returns a {@link SortedSet}, instead of the {@link Set} specified in the
* {@link Multimap} interface.
*/
@Override public SortedSet keySet() {
return (SortedSet) super.keySet();
}
/**
* @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
*/
private void writeObject(ObjectOutputStream stream) throws IOException {
stream.defaultWriteObject();
stream.writeObject(keyComparator());
stream.writeObject(valueComparator());
Serialization.writeMultimap(this, stream);
}
@SuppressWarnings("unchecked") // reading data stored by writeObject
private void readObject(ObjectInputStream stream)
throws IOException, ClassNotFoundException {
stream.defaultReadObject();
keyComparator = (Comparator) stream.readObject();
valueComparator = (Comparator) stream.readObject();
setMap(new TreeMap>(keyComparator));
Serialization.populateMultimap(this, stream);
}
private static final long serialVersionUID = 0;
}