001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.commons.collections4;
018
019import java.util.Comparator;
020import java.util.SortedMap;
021
022/**
023 * Defines a map that allows bidirectional lookup between key and values
024 * and retains both keys and values in sorted order.
025 * <p>
026 * Implementations should allow a value to be looked up from a key and
027 * a key to be looked up from a value with equal performance.
028 * </p>
029 *
030 * @param <K> the type of the keys in the map
031 * @param <V> the type of the values in the map
032 * @since 3.0
033 */
034public interface SortedBidiMap<K, V> extends OrderedBidiMap<K, V>, SortedMap<K, V> {
035
036    /**
037     * Gets a view of this map where the keys and values are reversed.
038     * <p>
039     * Changes to one map will be visible in the other and vice versa.
040     * This enables both directions of the map to be accessed equally.
041     * </p>
042     * <p>
043     * Implementations should seek to avoid creating a new object every time this
044     * method is called. See {@code AbstractMap.values()} etc. Calling this
045     * method on the inverse map should return the original.
046     * </p>
047     * <p>
048     * Implementations must return a {@code SortedBidiMap} instance,
049     * usually by forwarding to {@code inverseSortedBidiMap()}.
050     * </p>
051     *
052     * @return an inverted bidirectional map
053     */
054    @Override
055    SortedBidiMap<V, K> inverseBidiMap();
056
057    /**
058     * Gets the comparator used for the values in the value-to-key map aspect.
059     * @return Comparator&lt;? super V&gt;
060     */
061    Comparator<? super V> valueComparator();
062}