lucene/analysis/common/src/java/org/apache/lucene/analysis/fa/PersianNormalizer.java

/*
 * 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.lucene.analysis.fa;

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

/**
 * Normalizer for Persian.
 *
 * <p>Normalization is done in-place for efficiency, operating on a termbuffer.
 *
 * <p>Normalization is defined as:
 *
 * <ul>
 *   <li>Normalization of various heh + hamza forms and heh goal to heh.
 *   <li>Normalization of farsi yeh and yeh barree to arabic yeh
 *   <li>Normalization of persian keheh to arabic kaf
 * </ul>
 */
public class PersianNormalizer {
  public static final char YEH = '\u064A';

  public static final char FARSI_YEH = '\u06CC';

  public static final char YEH_BARREE = '\u06D2';

  public static final char KEHEH = '\u06A9';

  public static final char KAF = '\u0643';

  public static final char HAMZA_ABOVE = '\u0654';

  public static final char HEH_YEH = '\u06C0';

  public static final char HEH_GOAL = '\u06C1';

  public static final char HEH = '\u0647';

  /**
   * Normalize an input buffer of Persian 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 FARSI_YEH:
        case YEH_BARREE:
          s[i] = YEH;
          break;
        case KEHEH:
          s[i] = KAF;
          break;
        case HEH_YEH:
        case HEH_GOAL:
          s[i] = HEH;
          break;
        case HAMZA_ABOVE: // necessary for HEH + HAMZA
          len = delete(s, i, len);
          i--;
          break;
        default:
          break;
      }
    }

    return len;
  }
}