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.trie; 018 019import java.util.Map; 020 021import org.apache.commons.collections4.trie.analyzer.StringKeyAnalyzer; 022 023/** 024 * Implements a PATRICIA Trie (Practical Algorithm to Retrieve Information 025 * Coded in Alphanumeric). 026 * <p> 027 * A PATRICIA {@link org.apache.commons.collections4.Trie} is a compressed 028 * {@link org.apache.commons.collections4.Trie}. Instead of storing 029 * all data at the edges of the {@link org.apache.commons.collections4.Trie} 030 * (and having empty internal nodes), PATRICIA stores data in every node. 031 * This allows for very efficient traversal, insert, delete, predecessor, 032 * successor, prefix, range, and {@link #select(Object)} 033 * operations. All operations are performed at worst in O(K) time, where K 034 * is the number of bits in the largest item in the tree. In practice, 035 * operations actually take O(A(K)) time, where A(K) is the average number of 036 * bits of all items in the tree. 037 * </p> 038 * <p> 039 * Most importantly, PATRICIA requires very few comparisons to keys while 040 * doing any operation. While performing a lookup, each comparison (at most 041 * K of them, described above) will perform a single bit comparison against 042 * the given key, instead of comparing the entire key to another key. 043 * </p> 044 * <p> 045 * The {@link org.apache.commons.collections4.Trie} can return operations in 046 * lexicographical order using the 'prefixMap', 'submap', or 'iterator' methods. 047 * The {@link org.apache.commons.collections4.Trie} can also 048 * scan for items that are 'bitwise' (using an XOR metric) by the 'select' method. 049 * Bitwise closeness is determined by the {@link KeyAnalyzer} returning true or 050 * false for a bit being set or not in a given key. 051 * </p> 052 * <p> 053 * This PATRICIA {@link org.apache.commons.collections4.Trie} supports both variable 054 * length & fixed length keys. Some methods, such as {@link org.apache.commons.collections4.Trie#prefixMap(Object)} 055 * are suited only to variable length keys. 056 * </p> 057 * 058 * @param <V> the type of the values in this map 059 * 060 * @see <a href="https://en.wikipedia.org/wiki/Radix_tree">Radix Tree</a> 061 * @see <a href="https://users.monash.edu/~lloyd/tildeAlgDS/Tree/PATRICIA/">PATRICIA</a> 062 * @see <a href="https://www.imperialviolet.org/binary/critbit.pdf">Crit-Bit Tree</a> 063 * @since 4.0 064 */ 065public class PatriciaTrie<V> extends AbstractPatriciaTrie<String, V> { 066 067 private static final long serialVersionUID = 4446367780901817838L; 068 069 public PatriciaTrie() { 070 super(new StringKeyAnalyzer()); 071 } 072 073 public PatriciaTrie(final Map<? extends String, ? extends V> m) { 074 super(new StringKeyAnalyzer(), m); 075 } 076 077}