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 *      https://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 */
017
018package org.apache.commons.collections4;
019
020/**
021 * Defines a map that allows bidirectional lookup between key and values and retains and provides access to an ordering.
022 * <p>
023 * Implementations should allow a value to be looked up from a key and a key to be looked up from a value with equal performance.
024 * </p>
025 *
026 * @param <K> The type of the keys in the map.
027 * @param <V> The type of the values in the map.
028 * @since 3.0
029 */
030public interface OrderedBidiMap<K, V> extends BidiMap<K, V>, OrderedMap<K, V> {
031
032    /**
033     * Gets a view of this map where the keys and values are reversed.
034     * <p>
035     * Changes to one map will be visible in the other and vice versa. This enables both directions of the map to be accessed equally.
036     * </p>
037     * <p>
038     * Implementations should seek to avoid creating a new object every time this method is called. See {@code AbstractMap.values()} etc. Calling this method on
039     * the inverse map should return the original.
040     * </p>
041     * <p>
042     * Implementations must return an {@code OrderedBidiMap} instance, usually by forwarding to {@code inverseOrderedBidiMap()}.
043     * </p>
044     *
045     * @return An inverted bidirectional map.
046     */
047    @Override
048    OrderedBidiMap<V, K> inverseBidiMap();
049}