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Lucene example source code file (ArabicNormalizer.java)

This example Lucene source code file (ArabicNormalizer.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Lucene tags/keywords

alef, alef_hamza_below, alef_madda, damma, dotless_yeh, dotless_yeh, fatha, fathatan, heh, shadda, shadda, tatweel, yeh, yeh

The Lucene ArabicNormalizer.java source code

package org.apache.lucene.analysis.ar;

/**
 * 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.
 */

import static org.apache.lucene.analysis.util.StemmerUtil.*;

/**
 *  Normalizer for Arabic.
 *  <p>
 *  Normalization is done in-place for efficiency, operating on a termbuffer.
 *  <p>
 *  Normalization is defined as:
 *  <ul>
 *  <li> Normalization of hamza with alef seat to a bare alef.
 *  <li> Normalization of teh marbuta to heh
 *  <li> Normalization of dotless yeh (alef maksura) to yeh.
 *  <li> Removal of Arabic diacritics (the harakat)
 *  <li> Removal of tatweel (stretching character).
 * </ul>
 *
 */
public class ArabicNormalizer {
  public static final char ALEF = '\u0627';
  public static final char ALEF_MADDA = '\u0622';
  public static final char ALEF_HAMZA_ABOVE = '\u0623';
  public static final char ALEF_HAMZA_BELOW = '\u0625';

  public static final char YEH = '\u064A';
  public static final char DOTLESS_YEH = '\u0649';

  public static final char TEH_MARBUTA = '\u0629';
  public static final char HEH = '\u0647';

  public static final char TATWEEL = '\u0640';

  public static final char FATHATAN = '\u064B';
  public static final char DAMMATAN = '\u064C';
  public static final char KASRATAN = '\u064D';
  public static final char FATHA = '\u064E';
  public static final char DAMMA = '\u064F';
  public static final char KASRA = '\u0650';
  public static final char SHADDA = '\u0651';
  public static final char SUKUN = '\u0652';

  /**
   * Normalize an input buffer of Arabic text
   * 
   * @param s input buffer
   * @param len length of input buffer
   * @return length of input buffer after normalization
   */
  public int normalize(char s[], int len) {

    for (int i = 0; i < len; i++) {
      switch (s[i]) {
      case ALEF_MADDA:
      case ALEF_HAMZA_ABOVE:
      case ALEF_HAMZA_BELOW:
        s[i] = ALEF;
        break;
      case DOTLESS_YEH:
        s[i] = YEH;
        break;
      case TEH_MARBUTA:
        s[i] = HEH;
        break;
      case TATWEEL:
      case KASRATAN:
      case DAMMATAN:
      case FATHATAN:
      case FATHA:
      case DAMMA:
      case KASRA:
      case SHADDA:
      case SUKUN:
        len = delete(s, i, len);
        i--;
        break;
      default:
        break;
      }
    }

    return len;
  }
}

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