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package org.apache.lucene.analysis.fi;
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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* http://www.apache.org/licenses/LICENSE-2.0
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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* This algorithm is updated based on code located at:
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* http://members.unine.ch/jacques.savoy/clef/
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* Full copyright for that code follows:
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* Copyright (c) 2005, Jacques Savoy
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* All rights reserved.
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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* Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer. Redistributions in binary
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* form must reproduce the above copyright notice, this list of conditions and
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* the following disclaimer in the documentation and/or other materials
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* provided with the distribution. Neither the name of the author nor the names
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* of its contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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import static org.apache.lucene.analysis.util.StemmerUtil.*;
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* Light Stemmer for Finnish.
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* This stemmer implements the algorithm described in:
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* <i>Report on CLEF-2003 Monolingual Tracks</i>
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public class FinnishLightStemmer {
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public int stem(char s[], int len) {
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for (int i = 0; i < len; i++)
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case 'å': s[i] = 'a'; break;
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case 'ö': s[i] = 'o'; break;
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private int step1(char s[], int len) {
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if (endsWith(s, len, "kin"))
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return step1(s, len-3);
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if (endsWith(s, len, "ko"))
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return step1(s, len-2);
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if (endsWith(s, len, "dellinen"))
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if (endsWith(s, len, "dellisuus"))
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private int step2(char s[], int len) {
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if (endsWith(s, len, "lla")
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|| endsWith(s, len, "tse")
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|| endsWith(s, len, "sti"))
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if (endsWith(s, len, "ni"))
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if (endsWith(s, len, "aa"))
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return len-1; // aa -> a
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private int step3(char s[], int len) {
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if (endsWith(s, len, "nnen")) {
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if (endsWith(s, len, "ntena")) {
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if (endsWith(s, len, "tten"))
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if (endsWith(s, len, "eiden"))
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if (endsWith(s, len, "neen")
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|| endsWith(s, len, "niin")
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|| endsWith(s, len, "seen")
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|| endsWith(s, len, "teen")
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|| endsWith(s, len, "inen"))
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if (s[len-3] == 'h' && isVowel(s[len-2]) && s[len-1] == 'n')
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if (endsWith(s, len, "den")) {
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if (endsWith(s, len, "ksen")) {
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if (endsWith(s, len, "ssa")
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|| endsWith(s, len, "sta")
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|| endsWith(s, len, "lla")
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|| endsWith(s, len, "lta")
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|| endsWith(s, len, "tta")
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|| endsWith(s, len, "ksi")
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|| endsWith(s, len, "lle"))
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if (endsWith(s, len, "na")
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|| endsWith(s, len, "ne"))
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if (endsWith(s, len, "nei"))
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if (endsWith(s, len, "ja")
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|| endsWith(s, len, "ta"))
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if (s[len-1] == 'n' && isVowel(s[len-2]))
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private int norm1(char s[], int len) {
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if (len > 5 && endsWith(s, len, "hde")) {
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if (endsWith(s, len, "ei") || endsWith(s, len, "at"))
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case 'i': return len-1;
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private int norm2(char s[], int len) {
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for (int i = 1; i < len; i++) {
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(ch == 'k' || ch == 'p' || ch == 't'))
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len = delete(s, i--, len);
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private boolean isVowel(char ch) {
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case 'y': return true;
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default: return false;