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With inspiration from other libraries
/*
* 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.
*
* This class is immutable and thread-safe.
*
* @version $Id$
* @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(final String str) {
if (str == null || str.length() == 0) {
return str;
}
final int len = str.length();
final 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.
*
* - For Soundex, this return value ranges from 0 through 4: 0 indicates
* little or no similarity, and 4 indicates strong similarity or identical
* values.
* - For refined Soundex, the return value can be greater than 4.
*
*
* @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
* MS T-SQL DIFFERENCE
*
* @throws EncoderException
* if an error occurs encoding one of the strings
*/
static int difference(final StringEncoder encoder, final String s1, final 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.
*
* - For Soundex, this return value ranges from 0 through 4: 0 indicates
* little or no similarity, and 4 indicates strong similarity or identical
* values.
* - For refined Soundex, the return value can be greater than 4.
*
*
* @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
* MS T-SQL DIFFERENCE
*/
static int differenceEncoded(final String es1, final String es2) {
if (es1 == null || es2 == null) {
return 0;
}
final 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;
}
}