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 * https://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
18 package org.apache.commons.collections4;
19
20 import java.util.SortedMap;
21
22 /**
23 * 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>.
24 *
25 * @param <K> The type of the keys in this map.
26 * @param <V> The type of the values in this map.
27 * @since 4.0
28 */
29 public interface Trie<K, V> extends IterableSortedMap<K, V> {
30
31 /**
32 * Returns a view of this {@link Trie} of all elements that are prefixed by the given key.
33 * <p>
34 * In a {@link Trie} with fixed size keys, this is essentially a {@link #get(Object)} operation.
35 * </p>
36 * <p>
37 * For example, if the {@link Trie} contains 'Anna', 'Anael', 'Analu', 'Andreas', 'Andrea', 'Andres', and 'Anatole', then a lookup of 'And' would return
38 * 'Andreas', 'Andrea', and 'Andres'.
39 * </p>
40 *
41 * @param key The key used in the search.
42 * @return A {@link SortedMap} view of this {@link Trie} with all elements whose key is prefixed by the search key.
43 */
44 SortedMap<K, V> prefixMap(K key);
45 }