lucene/analysis/common/src/java/org/apache/lucene/analysis/pt/PortugueseLightStemmer.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.pt;


/* 
 * 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 Portuguese
 * <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 PortugueseLightStemmer {
  
  public int stem(char s[], int len) {
    if (len < 4)
      return len;
    
    len = removeSuffix(s, len);
    
    if (len > 3 && s[len-1] == 'a')
      len = normFeminine(s, len);
    
    if (len > 4)
      switch(s[len-1]) {
        case 'e':
        case 'a':
        case 'o': len--; break;
      }
    
    for (int i = 0; i < len; i++)
      switch(s[i]) {
        case 'à': 
        case 'á':
        case 'â':
        case 'ä': 
        case 'ã': s[i] = 'a'; break;
        case 'ò':
        case 'ó':
        case 'ô':
        case 'ö': 
        case 'õ': s[i] = 'o'; break;
        case 'è':
        case 'é':
        case 'ê':
        case 'ë': s[i] = 'e'; break;
        case 'ù':
        case 'ú':
        case 'û':
        case 'ü': s[i] = 'u'; break;
        case 'ì':
        case 'í':
        case 'î':
        case 'ï': s[i] = 'i'; break;
        case 'ç': s[i] = 'c'; break;
      }

    return len;
  }
  
  private int removeSuffix(char s[], int len) {
    if (len > 4 && endsWith(s, len, "es"))
      switch(s[len-3]) {
        case 'r':
        case 's':
        case 'l':
        case 'z': return len - 2;
      }
    
    if (len > 3 && endsWith(s, len, "ns")) {
      s[len - 2] = 'm';
      return len - 1;
    }
    
    if (len > 4 && (endsWith(s, len, "eis") || endsWith(s, len, "éis"))) {
      s[len - 3] = 'e';
      s[len - 2] = 'l';
      return len - 1;
    }
    
    if (len > 4 && endsWith(s, len, "ais")) {
      s[len - 2] = 'l';
      return len - 1;
    }
    
    if (len > 4 && endsWith(s, len, "óis")) {
      s[len - 3] = 'o';
      s[len - 2] = 'l';
      return len - 1;
    }
    
    if (len > 4 && endsWith(s, len, "is")) {
      s[len - 1] = 'l';
      return len;
    }
    
    if (len > 3 &&
        (endsWith(s, len, "ões") ||
         endsWith(s, len, "ães"))) {
      len--;
      s[len - 2] = 'ã';
      s[len - 1] = 'o';
      return len;
    }
    
    if (len > 6 && endsWith(s, len, "mente"))
      return len - 5;
    
    if (len > 3 && s[len-1] == 's')
      return len - 1;
    return len;
  }

  private int normFeminine(char s[], int len) {
    if (len > 7 && 
        (endsWith(s, len, "inha") ||
         endsWith(s, len, "iaca") ||
         endsWith(s, len, "eira"))) {
      s[len - 1] = 'o';
      return len;
    }
    
    if (len > 6) {
      if (endsWith(s, len, "osa") ||
          endsWith(s, len, "ica") ||
          endsWith(s, len, "ida") ||
          endsWith(s, len, "ada") ||
          endsWith(s, len, "iva") ||
          endsWith(s, len, "ama")) {
        s[len - 1] = 'o';
        return len;
      }
      
      if (endsWith(s, len, "ona")) {
        s[len - 3] = 'ã';
        s[len - 2] = 'o';
        return len - 1;
      }
      
      if (endsWith(s, len, "ora"))
        return len - 1;
      
      if (endsWith(s, len, "esa")) {
        s[len - 3] = 'ê';
        return len - 1;
      }
      
      if (endsWith(s, len, "na")) {
        s[len - 1] = 'o';
        return len;
      }
    }
    return len;
  }
}