diff options
Diffstat (limited to 'src/org/apache/commons/codec/language/RefinedSoundex.java')
| -rw-r--r-- | src/org/apache/commons/codec/language/RefinedSoundex.java | 186 |
1 files changed, 186 insertions, 0 deletions
diff --git a/src/org/apache/commons/codec/language/RefinedSoundex.java b/src/org/apache/commons/codec/language/RefinedSoundex.java new file mode 100644 index 0000000..dbf60fe --- /dev/null +++ b/src/org/apache/commons/codec/language/RefinedSoundex.java @@ -0,0 +1,186 @@ +/* + * Copyright 2001-2004 The Apache Software Foundation. + * + * Licensed 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,v 1.21 2004/06/05 18:32:04 ggregory Exp $ + */ +public class RefinedSoundex implements StringEncoder { + + /** + * This static variable contains an instance of the RefinedSoundex using + * the US_ENGLISH mapping. + */ + public static final RefinedSoundex US_ENGLISH = new RefinedSoundex(); + + /** + * RefinedSoundex is *refined* for a number of reasons one being that the + * mappings have been altered. This implementation contains default + * mappings for US English. + */ + public static final char[] US_ENGLISH_MAPPING = "01360240043788015936020505".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 char[] soundexMapping; + + /** + * Creates an instance of the RefinedSoundex object using the default US + * English mapping. + */ + public RefinedSoundex() { + this(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 = mapping; + } + + // BEGIN android-note + // Removed @see reference to SoundexUtils below, since the class isn't + // public. + // END android-note + /** + * 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 <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 java.lang.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(); + } +} |