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
020import java.util.SortedMap;
021
022/**
023 * Defines the interface for a prefix tree, an ordered tree data structure. For more information, see <a href="https://en.wikipedia.org/wiki/Trie">Tries</a>.
024 *
025 * @param <K> The type of the keys in this map.
026 * @param <V> The type of the values in this map.
027 * @since 4.0
028 */
029public interface Trie<K, V> extends IterableSortedMap<K, V> {
030
031    /**
032     * Returns a view of this {@link Trie} of all elements that are prefixed by the given key.
033     * <p>
034     * In a {@link Trie} with fixed size keys, this is essentially a {@link #get(Object)} operation.
035     * </p>
036     * <p>
037     * For example, if the {@link Trie} contains 'Anna', 'Anael', 'Analu', 'Andreas', 'Andrea', 'Andres', and 'Anatole', then a lookup of 'And' would return
038     * 'Andreas', 'Andrea', and 'Andres'.
039     * </p>
040     *
041     * @param key The key used in the search.
042     * @return A {@link SortedMap} view of this {@link Trie} with all elements whose key is prefixed by the search key.
043     */
044    SortedMap<K, V> prefixMap(K key);
045}