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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.commons.codec.language;

import org.apache.commons.codec.EncoderException;
import org.apache.commons.codec.StringEncoder;

/**
 * Encodes a string into a Refined Soundex value. A refined soundex code is
 * optimized for spell checking words. Soundex method originally developed by
 * Margaret Odell and Robert Russell.
 *
 * 

This class is immutable and thread-safe.

* * @version $Id$ */ public class RefinedSoundex implements StringEncoder { /** * Mapping: *
     * 0: A E I O U Y H W
     * 1: B P
     * 2: F V
     * 3: C K S
     * 4: G J
     * 5: Q X Z
     * 6: D T
     * 7: L
     * 8: M N
     * 9: R
     * 
* @since 1.4 */ // ABCDEFGHIJKLMNOPQRSTUVWXYZ public static final String US_ENGLISH_MAPPING_STRING = "01360240043788015936020505"; /** * RefinedSoundex is *refined* for a number of reasons one being that the * mappings have been altered. This implementation contains default * mappings for US English. */ private static final char[] US_ENGLISH_MAPPING = US_ENGLISH_MAPPING_STRING.toCharArray(); /** * Every letter of the alphabet is "mapped" to a numerical value. This char * array holds the values to which each letter is mapped. This * implementation contains a default map for US_ENGLISH */ private final char[] soundexMapping; /** * This static variable contains an instance of the RefinedSoundex using * the US_ENGLISH mapping. */ public static final RefinedSoundex US_ENGLISH = new RefinedSoundex(); /** * Creates an instance of the RefinedSoundex object using the default US * English mapping. */ public RefinedSoundex() { this.soundexMapping = US_ENGLISH_MAPPING; } /** * Creates a refined soundex instance using a custom mapping. This * constructor can be used to customize the mapping, and/or possibly * provide an internationalized mapping for a non-Western character set. * * @param mapping * Mapping array to use when finding the corresponding code for * a given character */ public RefinedSoundex(final char[] mapping) { this.soundexMapping = new char[mapping.length]; System.arraycopy(mapping, 0, this.soundexMapping, 0, mapping.length); } /** * Creates a refined Soundex instance using a custom mapping. This constructor can be used to customize the mapping, * and/or possibly provide an internationalized mapping for a non-Western character set. * * @param mapping * Mapping string to use when finding the corresponding code for a given character * @since 1.4 */ public RefinedSoundex(final String mapping) { this.soundexMapping = mapping.toCharArray(); } /** * Returns the number of characters in the two encoded Strings that are the * same. This return value ranges from 0 to the length of the shortest * encoded String: 0 indicates little or no similarity, and 4 out of 4 (for * example) indicates strong similarity or identical values. For refined * Soundex, the return value can be greater than 4. * * @param s1 * A String that will be encoded and compared. * @param s2 * A String that will be encoded and compared. * @return The number of characters in the two encoded Strings that are the * same from 0 to to the length of the shortest encoded String. * * @see SoundexUtils#difference(StringEncoder,String,String) * @see * MS T-SQL DIFFERENCE * * @throws EncoderException * if an error occurs encoding one of the strings * @since 1.3 */ public int difference(final String s1, final String s2) throws EncoderException { return SoundexUtils.difference(this, s1, s2); } /** * Encodes an Object using the refined soundex algorithm. This method is * provided in order to satisfy the requirements of the Encoder interface, * and will throw an EncoderException if the supplied object is not of type * java.lang.String. * * @param obj * Object to encode * @return An object (or type java.lang.String) containing the refined * soundex code which corresponds to the String supplied. * @throws EncoderException * if the parameter supplied is not of type java.lang.String */ @Override public Object encode(final Object obj) throws EncoderException { if (!(obj instanceof String)) { throw new EncoderException("Parameter supplied to RefinedSoundex encode is not of type java.lang.String"); } return soundex((String) obj); } /** * Encodes a String using the refined soundex algorithm. * * @param str * A String object to encode * @return A Soundex code corresponding to the String supplied */ @Override public String encode(final String str) { return soundex(str); } /** * Returns the mapping code for a given character. The mapping codes are * maintained in an internal char array named soundexMapping, and the * default values of these mappings are US English. * * @param c * char to get mapping for * @return A character (really a numeral) to return for the given char */ char getMappingCode(final char c) { if (!Character.isLetter(c)) { return 0; } return this.soundexMapping[Character.toUpperCase(c) - 'A']; } /** * Retrieves the Refined Soundex code for a given String object. * * @param str * String to encode using the Refined Soundex algorithm * @return A soundex code for the String supplied */ public String soundex(String str) { if (str == null) { return null; } str = SoundexUtils.clean(str); if (str.length() == 0) { return str; } final StringBuilder sBuf = new StringBuilder(); sBuf.append(str.charAt(0)); char last, current; last = '*'; for (int i = 0; i < str.length(); i++) { current = getMappingCode(str.charAt(i)); if (current == last) { continue; } else if (current != 0) { sBuf.append(current); } last = current; } return sBuf.toString(); } }




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