1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.collections4;
18
19 import java.util.SortedMap;
20
21 /**
22 * 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>.
23 *
24 * @param <K> the type of the keys in this map
25 * @param <V> the type of the values in this map
26 * @since 4.0
27 */
28 public interface Trie<K, V> extends IterableSortedMap<K, V> {
29
30 /**
31 * Returns a view of this {@link Trie} of all elements that are prefixed by the given key.
32 * <p>
33 * In a {@link Trie} with fixed size keys, this is essentially a {@link #get(Object)} operation.
34 * </p>
35 * <p>
36 * For example, if the {@link Trie} contains 'Anna', 'Anael', 'Analu', 'Andreas', 'Andrea', 'Andres', and 'Anatole', then a lookup of 'And' would return
37 * 'Andreas', 'Andrea', and 'Andres'.
38 * </p>
39 *
40 * @param key the key used in the search
41 * @return a {@link SortedMap} view of this {@link Trie} with all elements whose key is prefixed by the search key
42 */
43 SortedMap<K, V> prefixMap(K key);
44
45 }