org.apache.lucene.analysis.de.GermanMinimalStemmer Maven / Gradle / Ivy
package org.apache.lucene.analysis.de;
/*
* 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.
*/
/*
* 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.
*/
/**
* Minimal Stemmer for German.
*
* This stemmer implements the following algorithm:
* Morphologie et recherche d'information
* Jacques Savoy.
*/
public class GermanMinimalStemmer {
public int stem(char s[], int len) {
if (len < 5)
return len;
for (int i = 0; i < len; i++)
switch(s[i]) {
case 'ä': s[i] = 'a'; break;
case 'ö': s[i] = 'o'; break;
case 'ü': s[i] = 'u'; break;
}
if (len > 6 && s[len-3] == 'n' && s[len-2] == 'e' && s[len-1] == 'n')
return len - 3;
if (len > 5)
switch(s[len-1]) {
case 'n': if (s[len-2] == 'e') return len - 2; else break;
case 'e': if (s[len-2] == 's') return len - 2; else break;
case 's': if (s[len-2] == 'e') return len - 2; else break;
case 'r': if (s[len-2] == 'e') return len - 2; else break;
}
switch(s[len-1]) {
case 'n':
case 'e':
case 's':
case 'r': return len - 1;
}
return len;
}
}