    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
    018    package org.apache.commons.codec.language;
    019
    020    import org.apache.commons.codec.EncoderException;
    021    import 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     *
    030     * @version $Id: RefinedSoundex.java 1429868 2013-01-07 16:08:05Z ggregory $
    031     */
    032    public class RefinedSoundex implements StringEncoder {
    033
    034        /**
    035         * @since 1.4
    036         */
    037        public static final String US_ENGLISH_MAPPING_STRING = "01360240043788015936020505";
    038
    039       /**
    040         * RefinedSoundex is *refined* for a number of reasons one being that the
    041         * mappings have been altered. This implementation contains default
    042         * mappings for US English.
    043         */
    044        private static final char[] US_ENGLISH_MAPPING = US_ENGLISH_MAPPING_STRING.toCharArray();
    045
    046        /**
    047         * Every letter of the alphabet is "mapped" to a numerical value. This char
    048         * array holds the values to which each letter is mapped. This
    049         * implementation contains a default map for US_ENGLISH
    050         */
    051        private final char[] soundexMapping;
    052
    053        /**
    054         * This static variable contains an instance of the RefinedSoundex using
    055         * the US_ENGLISH mapping.
    056         */
    057        public static final RefinedSoundex US_ENGLISH = new RefinedSoundex();
    058
    059         /**
    060         * Creates an instance of the RefinedSoundex object using the default US
    061         * English mapping.
    062         */
    063        public RefinedSoundex() {
    064            this.soundexMapping = US_ENGLISH_MAPPING;
    065        }
    066
    067        /**
    068         * Creates a refined soundex instance using a custom mapping. This
    069         * constructor can be used to customize the mapping, and/or possibly
    070         * provide an internationalized mapping for a non-Western character set.
    071         *
    072         * @param mapping
    073         *                  Mapping array to use when finding the corresponding code for
    074         *                  a given character
    075         */
    076        public RefinedSoundex(final char[] mapping) {
    077            this.soundexMapping = new char[mapping.length];
    078            System.arraycopy(mapping, 0, this.soundexMapping, 0, mapping.length);
    079        }
    080
    081        /**
    082         * Creates a refined Soundex instance using a custom mapping. This constructor can be used to customize the mapping,
    083         * and/or possibly provide an internationalized mapping for a non-Western character set.
    084         *
    085         * @param mapping
    086         *            Mapping string to use when finding the corresponding code for a given character
    087         * @since 1.4
    088         */
    089        public RefinedSoundex(final String mapping) {
    090            this.soundexMapping = mapping.toCharArray();
    091        }
    092
    093        /**
    094         * Returns the number of characters in the two encoded Strings that are the
    095         * same. This return value ranges from 0 to the length of the shortest
    096         * encoded String: 0 indicates little or no similarity, and 4 out of 4 (for
    097         * example) indicates strong similarity or identical values. For refined
    098         * Soundex, the return value can be greater than 4.
    099         *
    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(final String s1, final 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(final 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(final 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(final 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            final 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    }