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.trie;
18
19 import java.util.Map;
20
21 import org.apache.commons.collections4.trie.analyzer.StringKeyAnalyzer;
22
23 /**
24 * Implementation of a PATRICIA Trie (Practical Algorithm to Retrieve Information
25 * Coded in Alphanumeric).
26 * <p>
27 * A PATRICIA {@link org.apache.commons.collections4.Trie} is a compressed
28 * {@link org.apache.commons.collections4.Trie}. Instead of storing
29 * all data at the edges of the {@link org.apache.commons.collections4.Trie}
30 * (and having empty internal nodes), PATRICIA stores data in every node.
31 * This allows for very efficient traversal, insert, delete, predecessor,
32 * successor, prefix, range, and {@link #select(Object)}
33 * operations. All operations are performed at worst in O(K) time, where K
34 * is the number of bits in the largest item in the tree. In practice,
35 * operations actually take O(A(K)) time, where A(K) is the average number of
36 * bits of all items in the tree.
37 * </p>
38 * <p>
39 * Most importantly, PATRICIA requires very few comparisons to keys while
40 * doing any operation. While performing a lookup, each comparison (at most
41 * K of them, described above) will perform a single bit comparison against
42 * the given key, instead of comparing the entire key to another key.
43 * </p>
44 * <p>
45 * The {@link org.apache.commons.collections4.Trie} can return operations in
46 * lexicographical order using the 'prefixMap', 'submap', or 'iterator' methods.
47 * The {@link org.apache.commons.collections4.Trie} can also
48 * scan for items that are 'bitwise' (using an XOR metric) by the 'select' method.
49 * Bitwise closeness is determined by the {@link KeyAnalyzer} returning true or
50 * false for a bit being set or not in a given key.
51 * </p>
52 * <p>
53 * This PATRICIA {@link org.apache.commons.collections4.Trie} supports both variable
54 * length & fixed length keys. Some methods, such as {@link org.apache.commons.collections4.Trie#prefixMap(Object)}
55 * are suited only to variable length keys.
56 * </p>
57 *
58 * @param <V> the type of the values in this map
59 *
60 * @see <a href="https://en.wikipedia.org/wiki/Radix_tree">Radix Tree</a>
61 * @see <a href="https://users.monash.edu/~lloyd/tildeAlgDS/Tree/PATRICIA/">PATRICIA</a>
62 * @see <a href="https://www.imperialviolet.org/binary/critbit.pdf">Crit-Bit Tree</a>
63 * @since 4.0
64 */
65 public class PatriciaTrie<V> extends AbstractPatriciaTrie<String, V> {
66
67 private static final long serialVersionUID = 4446367780901817838L;
68
69 public PatriciaTrie() {
70 super(new StringKeyAnalyzer());
71 }
72
73 public PatriciaTrie(final Map<? extends String, ? extends V> m) {
74 super(new StringKeyAnalyzer(), m);
75 }
76
77 }