    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 */
    017
    018package org.apache.commons.codec.language;
    019
    020import org.apache.commons.codec.EncoderException;
    021import org.apache.commons.codec.StringEncoder;
    022
    023/**
    024 * Encodes a string into a Refined Soundex value. A refined soundex code is
    025 * optimized for spell checking words. Soundex method originally developed by
    026 * <CITE>Margaret Odell</CITE> and <CITE>Robert Russell</CITE>.
    027 *
    028 * <p>This class is immutable and thread-safe.</p>
    029 */
    030public class RefinedSoundex implements StringEncoder {
    031
    032    /**
    033     * Mapping:
    034     * <pre>
    035     * 0: A E I O U Y H W
    036     * 1: B P
    037     * 2: F V
    038     * 3: C K S
    039     * 4: G J
    040     * 5: Q X Z
    041     * 6: D T
    042     * 7: L
    043     * 8: M N
    044     * 9: R
    045     * </pre>
    046     * @since 1.4
    047     */
    048    //                                                      ABCDEFGHIJKLMNOPQRSTUVWXYZ
    049    public static final String US_ENGLISH_MAPPING_STRING = "01360240043788015936020505";
    050
    051   /**
    052     * RefinedSoundex is *refined* for a number of reasons one being that the
    053     * mappings have been altered. This implementation contains default
    054     * mappings for US English.
    055     */
    056    private static final char[] US_ENGLISH_MAPPING = US_ENGLISH_MAPPING_STRING.toCharArray();
    057
    058    /**
    059     * Every letter of the alphabet is "mapped" to a numerical value. This char
    060     * array holds the values to which each letter is mapped. This
    061     * implementation contains a default map for US_ENGLISH
    062     */
    063    private final char[] soundexMapping;
    064
    065    /**
    066     * This static variable contains an instance of the RefinedSoundex using
    067     * the US_ENGLISH mapping.
    068     */
    069    public static final RefinedSoundex US_ENGLISH = new RefinedSoundex();
    070
    071     /**
    072     * Creates an instance of the RefinedSoundex object using the default US
    073     * English mapping.
    074     */
    075    public RefinedSoundex() {
    076        this.soundexMapping = US_ENGLISH_MAPPING;
    077    }
    078
    079    /**
    080     * Creates a refined soundex instance using a custom mapping. This
    081     * constructor can be used to customize the mapping, and/or possibly
    082     * provide an internationalized mapping for a non-Western character set.
    083     *
    084     * @param mapping
    085     *                  Mapping array to use when finding the corresponding code for
    086     *                  a given character
    087     */
    088    public RefinedSoundex(final char[] mapping) {
    089        this.soundexMapping = mapping.clone();
    090    }
    091
    092    /**
    093     * Creates a refined Soundex instance using a custom mapping. This constructor can be used to customize the mapping,
    094     * and/or possibly provide an internationalized mapping for a non-Western character set.
    095     *
    096     * @param mapping
    097     *            Mapping string to use when finding the corresponding code for a given character
    098     * @since 1.4
    099     */
    100    public RefinedSoundex(final String mapping) {
    101        this.soundexMapping = mapping.toCharArray();
    102    }
    103
    104    /**
    105     * Returns the number of characters in the two encoded Strings that are the
    106     * same. This return value ranges from 0 to the length of the shortest
    107     * encoded String: 0 indicates little or no similarity, and 4 out of 4 (for
    108     * example) indicates strong similarity or identical values. For refined
    109     * Soundex, the return value can be greater than 4.
    110     *
    111     * @param s1
    112     *                  A String that will be encoded and compared.
    113     * @param s2
    114     *                  A String that will be encoded and compared.
    115     * @return The number of characters in the two encoded Strings that are the
    116     *             same from 0 to the length of the shortest encoded String.
    117     *
    118     * @see SoundexUtils#difference(StringEncoder,String,String)
    119     * @see <a href="http://msdn.microsoft.com/library/default.asp?url=/library/en-us/tsqlref/ts_de-dz_8co5.asp">
    120     *          MS T-SQL DIFFERENCE</a>
    121     *
    122     * @throws EncoderException
    123     *                  if an error occurs encoding one of the strings
    124     * @since 1.3
    125     */
    126    public int difference(final String s1, final String s2) throws EncoderException {
    127        return SoundexUtils.difference(this, s1, s2);
    128    }
    129
    130    /**
    131     * Encodes an Object using the refined soundex algorithm. This method is
    132     * provided in order to satisfy the requirements of the Encoder interface,
    133     * and will throw an EncoderException if the supplied object is not of type
    134     * java.lang.String.
    135     *
    136     * @param obj
    137     *                  Object to encode
    138     * @return An object (or type java.lang.String) containing the refined
    139     *             soundex code which corresponds to the String supplied.
    140     * @throws EncoderException
    141     *                  if the parameter supplied is not of type java.lang.String
    142     */
    143    @Override
    144    public Object encode(final Object obj) throws EncoderException {
    145        if (!(obj instanceof String)) {
    146            throw new EncoderException("Parameter supplied to RefinedSoundex encode is not of type java.lang.String");
    147        }
    148        return soundex((String) obj);
    149    }
    150
    151    /**
    152     * Encodes a String using the refined soundex algorithm.
    153     *
    154     * @param str
    155     *                  A String object to encode
    156     * @return A Soundex code corresponding to the String supplied
    157     */
    158    @Override
    159    public String encode(final String str) {
    160        return soundex(str);
    161    }
    162
    163    /**
    164     * Returns the mapping code for a given character. The mapping codes are
    165     * maintained in an internal char array named soundexMapping, and the
    166     * default values of these mappings are US English.
    167     *
    168     * @param c
    169     *                  char to get mapping for
    170     * @return A character (really a numeral) to return for the given char
    171     */
    172    char getMappingCode(final char c) {
    173        if (!Character.isLetter(c)) {
    174            return 0;
    175        }
    176        return this.soundexMapping[Character.toUpperCase(c) - 'A'];
    177    }
    178
    179    /**
    180     * Retrieves the Refined Soundex code for a given String object.
    181     *
    182     * @param str
    183     *                  String to encode using the Refined Soundex algorithm
    184     * @return A soundex code for the String supplied
    185     */
    186    public String soundex(String str) {
    187        if (str == null) {
    188            return null;
    189        }
    190        str = SoundexUtils.clean(str);
    191        if (str.isEmpty()) {
    192            return str;
    193        }
    194
    195        final StringBuilder sBuf = new StringBuilder();
    196        sBuf.append(str.charAt(0));
    197
    198        char last, current;
    199        last = '*';
    200
    201        for (int i = 0; i < str.length(); i++) {
    202
    203            current = getMappingCode(str.charAt(i));
    204            if (current == last) {
    205                continue;
    206            }
    207            if (current != 0) {
    208                sBuf.append(current);
    209            }
    210
    211            last = current;
    212
    213        }
    214
    215        return sBuf.toString();
    216    }
    217}