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 package org.apache.commons.collections4.trie;
18
19 import java.util.Map;
20
21 import org.apache.commons.collections4.Trie;
22 import org.apache.commons.collections4.trie.analyzer.StringKeyAnalyzer;
23
24 /**
25 * Implements a PATRICIA Trie (Practical Algorithm to Retrieve Information
26 * Coded in Alphanumeric).
27 * <p>
28 * A PATRICIA {@link Trie} is a compressed
29 * {@link Trie}. Instead of storing
30 * all data at the edges of the {@link Trie}
31 * (and having empty internal nodes), PATRICIA stores data in every node.
32 * This allows for very efficient traversal, insert, delete, predecessor,
33 * successor, prefix, range, and {@link #select(Object)}
34 * operations. All operations are performed at worst in O(K) time, where K
35 * is the number of bits in the largest item in the tree. In practice,
36 * operations actually take O(A(K)) time, where A(K) is the average number of
37 * bits of all items in the tree.
38 * </p>
39 * <p>
40 * Most importantly, PATRICIA requires very few comparisons to keys while
41 * doing any operation. While performing a lookup, each comparison (at most
42 * K of them, described above) will perform a single bit comparison against
43 * the given key, instead of comparing the entire key to another key.
44 * </p>
45 * <p>
46 * The {@link Trie} can return operations in
47 * lexicographical order using the 'prefixMap', 'submap', or 'iterator' methods.
48 * The {@link Trie} can also
49 * scan for items that are 'bitwise' (using an XOR metric) by the 'select' method.
50 * Bitwise closeness is determined by the {@link KeyAnalyzer} returning true or
51 * false for a bit being set or not in a given key.
52 * </p>
53 * <p>
54 * This PATRICIA {@link Trie} supports both variable
55 * length & fixed length keys. Some methods, such as {@link org.apache.commons.collections4.Trie#prefixMap(Object)}
56 * are suited only to variable length keys.
57 * </p>
58 *
59 * @param <V> The type of the values in this map
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 /**
70 * Constructs a new instance.
71 */
72 public PatriciaTrie() {
73 super(StringKeyAnalyzer.INSTANCE);
74 }
75
76 /**
77 * Constructs a new instance.
78 *
79 * @param map mappings to be stored in this map.
80 */
81 public PatriciaTrie(final Map<? extends String, ? extends V> map) {
82 super(StringKeyAnalyzer.INSTANCE, map);
83 }
84
85 }