    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.SortedMap;
    020
    021/**
    022 * Defines the interface for a prefix tree, an ordered tree data structure. For
    023 * more information, see <a href="http://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
    033     * by the given key.
    034     * <p>
    035     * In a {@link Trie} with fixed size keys, this is essentially a
    036     * {@link #get(Object)} operation.
    037     * <p>
    038     * For example, if the {@link Trie} contains 'Anna', 'Anael',
    039     * 'Analu', 'Andreas', 'Andrea', 'Andres', and 'Anatole', then
    040     * a lookup of 'And' would return 'Andreas', 'Andrea', and 'Andres'.
    041     *
    042     * @param key  the key used in the search
    043     * @return a {@link SortedMap} view of this {@link Trie} with all elements whose
    044     *   key is prefixed by the search key
    045     */
    046    SortedMap<K, V> prefixMap(K key);
    047
    048}