lucene/analysis/common/src/java/org/apache/lucene/analysis/fr/FrenchLightStemmer.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.fr;

/*
 * This algorithm is updated based on code located at:
 * http://members.unine.ch/jacques.savoy/clef/
 *
 * Full copyright for that code follows:
 */

/*
 * Copyright (c) 2005, Jacques Savoy
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer. Redistributions in binary
 * form must reproduce the above copyright notice, this list of conditions and
 * the following disclaimer in the documentation and/or other materials
 * provided with the distribution. Neither the name of the author nor the names
 * of its contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

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

/**
 * Light Stemmer for French.
 *
 * <p>This stemmer implements the "UniNE" algorithm in: <i>Light Stemming Approaches for the French,
 * Portuguese, German and Hungarian Languages</i> Jacques Savoy
 */
public class FrenchLightStemmer {

  public int stem(char s[], int len) {
    if (len > 5 && s[len - 1] == 'x') {
      if (s[len - 3] == 'a' && s[len - 2] == 'u' && s[len - 4] != 'e') s[len - 2] = 'l';
      len--;
    }

    if (len > 3 && s[len - 1] == 'x') len--;

    if (len > 3 && s[len - 1] == 's') len--;

    if (len > 9 && endsWith(s, len, "issement")) {
      len -= 6;
      s[len - 1] = 'r';
      return norm(s, len);
    }

    if (len > 8 && endsWith(s, len, "issant")) {
      len -= 4;
      s[len - 1] = 'r';
      return norm(s, len);
    }

    if (len > 6 && endsWith(s, len, "ement")) {
      len -= 4;
      if (len > 3 && endsWith(s, len, "ive")) {
        len--;
        s[len - 1] = 'f';
      }
      return norm(s, len);
    }

    if (len > 11 && endsWith(s, len, "ficatrice")) {
      len -= 5;
      s[len - 2] = 'e';
      s[len - 1] = 'r';
      return norm(s, len);
    }

    if (len > 10 && endsWith(s, len, "ficateur")) {
      len -= 4;
      s[len - 2] = 'e';
      s[len - 1] = 'r';
      return norm(s, len);
    }

    if (len > 9 && endsWith(s, len, "catrice")) {
      len -= 3;
      s[len - 4] = 'q';
      s[len - 3] = 'u';
      s[len - 2] = 'e';
      // s[len-1] = 'r' <-- unnecessary, already 'r'.
      return norm(s, len);
    }

    if (len > 8 && endsWith(s, len, "cateur")) {
      len -= 2;
      s[len - 4] = 'q';
      s[len - 3] = 'u';
      s[len - 2] = 'e';
      s[len - 1] = 'r';
      return norm(s, len);
    }

    if (len > 8 && endsWith(s, len, "atrice")) {
      len -= 4;
      s[len - 2] = 'e';
      s[len - 1] = 'r';
      return norm(s, len);
    }

    if (len > 7 && endsWith(s, len, "ateur")) {
      len -= 3;
      s[len - 2] = 'e';
      s[len - 1] = 'r';
      return norm(s, len);
    }

    if (len > 6 && endsWith(s, len, "trice")) {
      len--;
      s[len - 3] = 'e';
      s[len - 2] = 'u';
      s[len - 1] = 'r';
    }

    if (len > 5 && endsWith(s, len, "ième")) return norm(s, len - 4);

    if (len > 7 && endsWith(s, len, "teuse")) {
      len -= 2;
      s[len - 1] = 'r';
      return norm(s, len);
    }

    if (len > 6 && endsWith(s, len, "teur")) {
      len--;
      s[len - 1] = 'r';
      return norm(s, len);
    }

    if (len > 5 && endsWith(s, len, "euse")) return norm(s, len - 2);

    if (len > 8 && endsWith(s, len, "ère")) {
      len--;
      s[len - 2] = 'e';
      return norm(s, len);
    }

    if (len > 7 && endsWith(s, len, "ive")) {
      len--;
      s[len - 1] = 'f';
      return norm(s, len);
    }

    if (len > 4 && (endsWith(s, len, "folle") || endsWith(s, len, "molle"))) {
      len -= 2;
      s[len - 1] = 'u';
      return norm(s, len);
    }

    if (len > 9 && endsWith(s, len, "nnelle")) return norm(s, len - 5);

    if (len > 9 && endsWith(s, len, "nnel")) return norm(s, len - 3);

    if (len > 4 && endsWith(s, len, "ète")) {
      len--;
      s[len - 2] = 'e';
    }

    if (len > 8 && endsWith(s, len, "ique")) len -= 4;

    if (len > 8 && endsWith(s, len, "esse")) return norm(s, len - 3);

    if (len > 7 && endsWith(s, len, "inage")) return norm(s, len - 3);

    if (len > 9 && endsWith(s, len, "isation")) {
      len -= 7;
      if (len > 5 && endsWith(s, len, "ual")) s[len - 2] = 'e';
      return norm(s, len);
    }

    if (len > 9 && endsWith(s, len, "isateur")) return norm(s, len - 7);

    if (len > 8 && endsWith(s, len, "ation")) return norm(s, len - 5);

    if (len > 8 && endsWith(s, len, "ition")) return norm(s, len - 5);

    return norm(s, len);
  }

  private int norm(char s[], int len) {
    if (len > 4) {
      for (int i = 0; i < len; i++)
        switch (s[i]) {
          case 'à':
          case 'á':
          case 'â':
            s[i] = 'a';
            break;
          case 'ô':
            s[i] = 'o';
            break;
          case 'è':
          case 'é':
          case 'ê':
            s[i] = 'e';
            break;
          case 'ù':
          case 'û':
            s[i] = 'u';
            break;
          case 'î':
            s[i] = 'i';
            break;
          case 'ç':
            s[i] = 'c';
            break;
        }

      char ch = s[0];
      for (int i = 1; i < len; i++) {
        if (s[i] == ch && Character.isLetter(ch)) len = delete(s, i--, len);
        else ch = s[i];
      }
    }

    if (len > 4 && endsWith(s, len, "ie")) len -= 2;

    if (len > 4) {
      if (s[len - 1] == 'r') len--;
      if (s[len - 1] == 'e') len--;
      if (s[len - 1] == 'e') len--;
      if (s[len - 1] == s[len - 2] && Character.isLetter(s[len - 1])) len--;
    }
    return len;
  }
}