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.logging.log4j.util;
018
019/**
020 * An extension of {@code ReadOnlyStringMap} that imposes a total ordering on its keys.
021 * The map is ordered according to the natural ordering of its keys. This order is reflected when
022 * {@link #forEach(BiConsumer) consuming} the key-value pairs with a {@link BiConsumer} or a {@link TriConsumer}.
023 * <p>
024 * This interface views all key-value pairs as a sequence ordered by key, and allows
025 * keys and values to be accessed by their index in the sequence.
026 * </p>
027 *
028 * @see ReadOnlyStringMap
029 * @since 2.8
030 */
031public interface IndexedReadOnlyStringMap extends ReadOnlyStringMap {
032
033    /**
034     * Viewing all key-value pairs as a sequence sorted by key, this method returns the key at the specified index,
035     * or {@code null} if the specified index is less than zero or greater or equal to the size of this collection.
036     *
037     * @param index the index of the key to return
038     * @return the key at the specified index or {@code null}
039     */
040    String getKeyAt(final int index);
041
042    /**
043     * Viewing all key-value pairs as a sequence sorted by key, this method returns the value at the specified index,
044     * or {@code null} if the specified index is less than zero or greater or equal to the size of this collection.
045     *
046     * @param index the index of the value to return
047     * @return the value at the specified index or {@code null}
048     */
049    <V> V getValueAt(final int index);
050
051    /**
052     * Viewing all key-value pairs as a sequence sorted by key, this method returns the index of the specified key in
053     * that sequence. If the specified key is not found, this method returns {@code (-(insertion point) - 1)}.
054     *
055     * @param key the key whose index in the ordered sequence of keys to return
056     * @return the index of the specified key or {@code (-(insertion point) - 1)} if the key is not found.
057     *          The insertion point is defined as the point at which the key would be inserted into the array:
058     *          the index of the first element in the range greater than the key, or {@code size()} if all elements
059     *          are less than the specified key. Note that this guarantees that the return value will be &gt;= 0
060     *          if and only if the key is found.
061     */
062    int indexOfKey(final String key);
063}