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
18 package org.apache.commons.codec.language;
19
20 import org.apache.commons.codec.EncoderException;
21 import org.apache.commons.codec.StringEncoder;
22
23 /**
24 * Encodes a string into a Refined Soundex value. A refined soundex code is
25 * optimized for spell checking words. Soundex method originally developed by
26 * <CITE>Margaret Odell</CITE> and <CITE>Robert Russell</CITE>.
27 *
28 * <p>This class is immutable and thread-safe.</p>
29 *
30 * @version $Id: RefinedSoundex.html 889935 2013-12-11 05:05:13Z ggregory $
31 */
32 public class RefinedSoundex implements StringEncoder {
33
34 /**
35 * @since 1.4
36 */
37 public static final String US_ENGLISH_MAPPING_STRING = "01360240043788015936020505";
38
39 /**
40 * RefinedSoundex is *refined* for a number of reasons one being that the
41 * mappings have been altered. This implementation contains default
42 * mappings for US English.
43 */
44 private static final char[] US_ENGLISH_MAPPING = US_ENGLISH_MAPPING_STRING.toCharArray();
45
46 /**
47 * Every letter of the alphabet is "mapped" to a numerical value. This char
48 * array holds the values to which each letter is mapped. This
49 * implementation contains a default map for US_ENGLISH
50 */
51 private final char[] soundexMapping;
52
53 /**
54 * This static variable contains an instance of the RefinedSoundex using
55 * the US_ENGLISH mapping.
56 */
57 public static final RefinedSoundex US_ENGLISH = new RefinedSoundex();
58
59 /**
60 * Creates an instance of the RefinedSoundex object using the default US
61 * English mapping.
62 */
63 public RefinedSoundex() {
64 this.soundexMapping = US_ENGLISH_MAPPING;
65 }
66
67 /**
68 * Creates a refined soundex instance using a custom mapping. This
69 * constructor can be used to customize the mapping, and/or possibly
70 * provide an internationalized mapping for a non-Western character set.
71 *
72 * @param mapping
73 * Mapping array to use when finding the corresponding code for
74 * a given character
75 */
76 public RefinedSoundex(char[] mapping) {
77 this.soundexMapping = new char[mapping.length];
78 System.arraycopy(mapping, 0, this.soundexMapping, 0, mapping.length);
79 }
80
81 /**
82 * Creates a refined Soundex instance using a custom mapping. This constructor can be used to customize the mapping,
83 * and/or possibly provide an internationalized mapping for a non-Western character set.
84 *
85 * @param mapping
86 * Mapping string to use when finding the corresponding code for a given character
87 * @since 1.4
88 */
89 public RefinedSoundex(String mapping) {
90 this.soundexMapping = mapping.toCharArray();
91 }
92
93 /**
94 * Returns the number of characters in the two encoded Strings that are the
95 * same. This return value ranges from 0 to the length of the shortest
96 * encoded String: 0 indicates little or no similarity, and 4 out of 4 (for
97 * example) indicates strong similarity or identical values. For refined
98 * Soundex, the return value can be greater than 4.
99 *
100 * @param s1
101 * A String that will be encoded and compared.
102 * @param s2
103 * A String that will be encoded and compared.
104 * @return The number of characters in the two encoded Strings that are the
105 * same from 0 to to the length of the shortest encoded String.
106 *
107 * @see SoundexUtils#difference(StringEncoder,String,String)
108 * @see <a href="http://msdn.microsoft.com/library/default.asp?url=/library/en-us/tsqlref/ts_de-dz_8co5.asp">
109 * MS T-SQL DIFFERENCE</a>
110 *
111 * @throws EncoderException
112 * if an error occurs encoding one of the strings
113 * @since 1.3
114 */
115 public int difference(String s1, String s2) throws EncoderException {
116 return SoundexUtils.difference(this, s1, s2);
117 }
118
119 /**
120 * Encodes an Object using the refined soundex algorithm. This method is
121 * provided in order to satisfy the requirements of the Encoder interface,
122 * and will throw an EncoderException if the supplied object is not of type
123 * java.lang.String.
124 *
125 * @param obj
126 * Object to encode
127 * @return An object (or type java.lang.String) containing the refined
128 * soundex code which corresponds to the String supplied.
129 * @throws EncoderException
130 * if the parameter supplied is not of type java.lang.String
131 */
132 @Override
133 public Object encode(Object obj) throws EncoderException {
134 if (!(obj instanceof String)) {
135 throw new EncoderException("Parameter supplied to RefinedSoundex encode is not of type java.lang.String");
136 }
137 return soundex((String) obj);
138 }
139
140 /**
141 * Encodes a String using the refined soundex algorithm.
142 *
143 * @param str
144 * A String object to encode
145 * @return A Soundex code corresponding to the String supplied
146 */
147 @Override
148 public String encode(String str) {
149 return soundex(str);
150 }
151
152 /**
153 * Returns the mapping code for a given character. The mapping codes are
154 * maintained in an internal char array named soundexMapping, and the
155 * default values of these mappings are US English.
156 *
157 * @param c
158 * char to get mapping for
159 * @return A character (really a numeral) to return for the given char
160 */
161 char getMappingCode(char c) {
162 if (!Character.isLetter(c)) {
163 return 0;
164 }
165 return this.soundexMapping[Character.toUpperCase(c) - 'A'];
166 }
167
168 /**
169 * Retrieves the Refined Soundex code for a given String object.
170 *
171 * @param str
172 * String to encode using the Refined Soundex algorithm
173 * @return A soundex code for the String supplied
174 */
175 public String soundex(String str) {
176 if (str == null) {
177 return null;
178 }
179 str = SoundexUtils.clean(str);
180 if (str.length() == 0) {
181 return str;
182 }
183
184 StringBuilder sBuf = new StringBuilder();
185 sBuf.append(str.charAt(0));
186
187 char last, current;
188 last = '*';
189
190 for (int i = 0; i < str.length(); i++) {
191
192 current = getMappingCode(str.charAt(i));
193 if (current == last) {
194 continue;
195 } else if (current != 0) {
196 sBuf.append(current);
197 }
198
199 last = current;
200
201 }
202
203 return sBuf.toString();
204 }
205 }