    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 *      https://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;
    022import org.apache.commons.collections4.trie.analyzer.StringKeyAnalyzer;
    023
    024/**
    025 * Implements a PATRICIA Trie (Practical Algorithm to Retrieve Information
    026 * Coded in Alphanumeric).
    027 * <p>
    028 * A PATRICIA {@link Trie} is a compressed
    029 * {@link Trie}. Instead of storing
    030 * all data at the edges of the {@link Trie}
    031 * (and having empty internal nodes), PATRICIA stores data in every node.
    032 * This allows for very efficient traversal, insert, delete, predecessor,
    033 * successor, prefix, range, and {@link #select(Object)}
    034 * operations. All operations are performed at worst in O(K) time, where K
    035 * is the number of bits in the largest item in the tree. In practice,
    036 * operations actually take O(A(K)) time, where A(K) is the average number of
    037 * bits of all items in the tree.
    038 * </p>
    039 * <p>
    040 * Most importantly, PATRICIA requires very few comparisons to keys while
    041 * doing any operation. While performing a lookup, each comparison (at most
    042 * K of them, described above) will perform a single bit comparison against
    043 * the given key, instead of comparing the entire key to another key.
    044 * </p>
    045 * <p>
    046 * The {@link Trie} can return operations in
    047 * lexicographical order using the 'prefixMap', 'submap', or 'iterator' methods.
    048 * The {@link Trie} can also
    049 * scan for items that are 'bitwise' (using an XOR metric) by the 'select' method.
    050 * Bitwise closeness is determined by the {@link KeyAnalyzer} returning true or
    051 * false for a bit being set or not in a given key.
    052 * </p>
    053 * <p>
    054 * This PATRICIA {@link Trie} supports both variable
    055 * length &amp; fixed length keys. Some methods, such as {@link org.apache.commons.collections4.Trie#prefixMap(Object)}
    056 * are suited only to variable length keys.
    057 * </p>
    058 *
    059 * @param <V> The type of the values in this map
    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    /**
    070     * Constructs a new instance.
    071     */
    072    public PatriciaTrie() {
    073        super(StringKeyAnalyzer.INSTANCE);
    074    }
    075
    076    /**
    077     * Constructs a new instance.
    078     *
    079     * @param map mappings to be stored in this map.
    080     */
    081    public PatriciaTrie(final Map<? extends String, ? extends V> map) {
    082        super(StringKeyAnalyzer.INSTANCE, map);
    083    }
    084
    085}