package org.apache.lucene.analysis.ru;
/**
* 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.
*/
import static org.apache.lucene.analysis.util.StemmerUtil.*;
/**
* Light Stemmer for Russian.
* <p>
* This stemmer implements the following algorithm:
* <i>Indexing and Searching Strategies for the Russian Language.</i>
* Ljiljana Dolamic and Jacques Savoy.
*/
public class RussianLightStemmer {
public int stem(char s[], int len) {
len = removeCase(s, len);
return normalize(s, len);
}
private int normalize(char s[], int len) {
if (len > 3)
switch(s[len-1]) {
case 'ь':
case 'и': return len - 1;
case 'н': if (s[len-2] == 'н') return len - 1;
}
return len;
}
private int removeCase(char s[], int len) {
if (len > 6 &&
(endsWith(s, len, "иями") ||
endsWith(s, len, "оями")))
return len - 4;
if (len > 5 &&
(endsWith(s, len, "иям") ||
endsWith(s, len, "иях") ||
endsWith(s, len, "оях") ||
endsWith(s, len, "ями") ||
endsWith(s, len, "оям") ||
endsWith(s, len, "оьв") ||
endsWith(s, len, "ами") ||
endsWith(s, len, "его") ||
endsWith(s, len, "ему") ||
endsWith(s, len, "ери") ||
endsWith(s, len, "ими") ||
endsWith(s, len, "ого") ||
endsWith(s, len, "ому") ||
endsWith(s, len, "ыми") ||
endsWith(s, len, "оев")))
return len - 3;
if (len > 4 &&
(endsWith(s, len, "ая") ||
endsWith(s, len, "яя") ||
endsWith(s, len, "ях") ||
endsWith(s, len, "юю") ||
endsWith(s, len, "ах") ||
endsWith(s, len, "ею") ||
endsWith(s, len, "их") ||
endsWith(s, len, "ия") ||
endsWith(s, len, "ию") ||
endsWith(s, len, "ьв") ||
endsWith(s, len, "ою") ||
endsWith(s, len, "ую") ||
endsWith(s, len, "ям") ||
endsWith(s, len, "ых") ||
endsWith(s, len, "ея") ||
endsWith(s, len, "ам") ||
endsWith(s, len, "ем") ||
endsWith(s, len, "ей") ||
endsWith(s, len, "ём") ||
endsWith(s, len, "ев") ||
endsWith(s, len, "ий") ||
endsWith(s, len, "им") ||
endsWith(s, len, "ое") ||
endsWith(s, len, "ой") ||
endsWith(s, len, "ом") ||
endsWith(s, len, "ов") ||
endsWith(s, len, "ые") ||
endsWith(s, len, "ый") ||
endsWith(s, len, "ым") ||
endsWith(s, len, "ми")))
return len - 2;
if (len > 3)
switch(s[len-1]) {
case 'а':
case 'е':
case 'и':
case 'о':
case 'у':
case 'й':
case 'ы':
case 'я':
case 'ь': return len - 1;
}
return len;
}
}