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;
  
  /**
   * Utility methods for {@link Soundex} and {@link RefinedSoundex} classes.
   * 
   * @author Apache Software Foundation
   * @version $Id: SoundexUtils.java 658834 2008-05-21 19:57:51Z niallp $
   * @since 1.3
   */
  final class SoundexUtils {
  
      /**
       * Cleans up the input string before Soundex processing by only returning
       * upper case letters.
       * 
       * @param str
       *                  The String to clean.
       * @return A clean String.
       */
      static String clean(String str) {
          if (str == null || str.length() == 0) {
              return str;
          }
          int len = str.length();
          char[] chars = new char[len];
          int count = 0;
          for (int i = 0; i < len; i++) {
              if (Character.isLetter(str.charAt(i))) {
                  chars[count++] = str.charAt(i);
              }
          }
          if (count == len) {
              return str.toUpperCase(java.util.Locale.ENGLISH);
          }
          return new String(chars, 0, count).toUpperCase(java.util.Locale.ENGLISH);
      }
  
      /**
       * Encodes the Strings and returns the number of characters in the two
       * encoded Strings that are the same.
       * <ul>
       * <li>For Soundex, this return value ranges from 0 through 4: 0 indicates
       * little or no similarity, and 4 indicates strong similarity or identical
       * values.</li>
       * <li>For refined Soundex, the return value can be greater than 4.</li>
       * </ul>
       * 
       * @param encoder
       *                  The encoder to use to encode the Strings.
       * @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 Soundex encoded Strings that
       *             are the same.
       * 
       * @see #differenceEncoded(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
       */
      static int difference(StringEncoder encoder, String s1, String s2) throws EncoderException {
          return differenceEncoded(encoder.encode(s1), encoder.encode(s2));
      }
  
      /**
       * Returns the number of characters in the two Soundex encoded Strings that
       * are the same.
       * <ul>
       * <li>For Soundex, this return value ranges from 0 through 4: 0 indicates
       * little or no similarity, and 4 indicates strong similarity or identical
       * values.</li>
       * <li>For refined Soundex, the return value can be greater than 4.</li>
       * </ul>
       * 
       * @param es1
       *                  An encoded String.
       * @param es2
       *                  An encoded String.
       * @return The number of characters in the two Soundex encoded Strings that
       *             are the same.
       * 
       * @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>
       */
      static int differenceEncoded(String es1, String es2) {
  
          if (es1 == null || es2 == null) {
              return 0;
          }
          int lengthToMatch = Math.min(es1.length(), es2.length());
          int diff = 0;
          for (int i = 0; i < lengthToMatch; i++) {
              if (es1.charAt(i) == es2.charAt(i)) {
                  diff++;
              }
          }
          return diff;
      }
  
  }
  