content: /*
   * 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
   * <CITE>Margaret Odell</CITE> and <CITE>Robert Russell</CITE>.
   * 
   * @author Apache Software Foundation
   * @version $Id: RefinedSoundex.java 1064455 2011-01-28 04:40:27Z ggregory $
   */
  public class RefinedSoundex implements StringEncoder {
  
      /**
       * @since 1.4
       */
      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(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(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 <a href="http://msdn.microsoft.com/library/default.asp?url=/library/en-us/tsqlref/ts_de-dz_8co5.asp">
       *          MS T-SQL DIFFERENCE</a>
       * 
       * @throws EncoderException
       *                  if an error occurs encoding one of the strings
       * @since 1.3
       */
      public int difference(String s1, 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 pObject
       *                  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
       */
      public Object encode(Object pObject) throws EncoderException {
          if (!(pObject instanceof String)) {
              throw new EncoderException("Parameter supplied to RefinedSoundex encode is not of type java.lang.String");
          }
          return soundex((String) pObject);
      }
  
      /**
       * Encodes a String using the refined soundex algorithm.
       * 
       * @param pString
       *                  A String object to encode
       * @return A Soundex code corresponding to the String supplied
       */
      public String encode(String pString) {
          return soundex(pString);
      }
  
      /**
       * 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(char c) {
          if (!Character.isLetter(c)) {
              return 0;
          }
          return this.soundexMapping[Character.toUpperCase(c) - 'A'];
      }
  
      /**
       * Retreives 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;
          }
  
          StringBuffer sBuf = new StringBuffer();
          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();
      }
  }
  