| using Lucene.Net.Analysis.Util; |
| |
| namespace Lucene.Net.Analysis.Fi |
| { |
| /* |
| * 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. |
| */ |
| |
| /// <summary> |
| /// Light Stemmer for Finnish. |
| /// <para> |
| /// This stemmer implements the algorithm described in: |
| /// <c>Report on CLEF-2003 Monolingual Tracks</c> |
| /// Jacques Savoy |
| /// </para> |
| /// </summary> |
| public class FinnishLightStemmer |
| { |
| public virtual int Stem(char[] s, int len) |
| { |
| if (len < 4) |
| { |
| return len; |
| } |
| |
| for (int i = 0; i < len; i++) |
| { |
| switch (s[i]) |
| { |
| case 'ä': |
| case 'å': |
| s[i] = 'a'; |
| break; |
| case 'ö': |
| s[i] = 'o'; |
| break; |
| } |
| } |
| |
| len = Step1(s, len); |
| len = Step2(s, len); |
| len = Step3(s, len); |
| len = Norm1(s, len); |
| len = Norm2(s, len); |
| return len; |
| } |
| |
| private int Step1(char[] s, int len) |
| { |
| if (len > 8) |
| { |
| if (StemmerUtil.EndsWith(s, len, "kin")) |
| { |
| return Step1(s, len - 3); |
| } |
| if (StemmerUtil.EndsWith(s, len, "ko")) |
| { |
| return Step1(s, len - 2); |
| } |
| } |
| |
| if (len > 11) |
| { |
| if (StemmerUtil.EndsWith(s, len, "dellinen")) |
| { |
| return len - 8; |
| } |
| if (StemmerUtil.EndsWith(s, len, "dellisuus")) |
| { |
| return len - 9; |
| } |
| } |
| return len; |
| } |
| |
| private int Step2(char[] s, int len) |
| { |
| if (len > 5) |
| { |
| if (StemmerUtil.EndsWith(s, len, "lla") || StemmerUtil.EndsWith(s, len, "tse") || StemmerUtil.EndsWith(s, len, "sti")) |
| { |
| return len - 3; |
| } |
| |
| if (StemmerUtil.EndsWith(s, len, "ni")) |
| { |
| return len - 2; |
| } |
| |
| if (StemmerUtil.EndsWith(s, len, "aa")) |
| { |
| return len - 1; // aa -> a |
| } |
| } |
| |
| return len; |
| } |
| |
| private int Step3(char[] s, int len) |
| { |
| if (len > 8) |
| { |
| if (StemmerUtil.EndsWith(s, len, "nnen")) |
| { |
| s[len - 4] = 's'; |
| return len - 3; |
| } |
| |
| if (StemmerUtil.EndsWith(s, len, "ntena")) |
| { |
| s[len - 5] = 's'; |
| return len - 4; |
| } |
| |
| if (StemmerUtil.EndsWith(s, len, "tten")) |
| { |
| return len - 4; |
| } |
| |
| if (StemmerUtil.EndsWith(s, len, "eiden")) |
| { |
| return len - 5; |
| } |
| } |
| |
| if (len > 6) |
| { |
| if (StemmerUtil.EndsWith(s, len, "neen") || StemmerUtil.EndsWith(s, len, "niin") || StemmerUtil.EndsWith(s, len, "seen") || StemmerUtil.EndsWith(s, len, "teen") || StemmerUtil.EndsWith(s, len, "inen")) |
| { |
| return len - 4; |
| } |
| |
| if (s[len - 3] == 'h' && IsVowel(s[len - 2]) && s[len - 1] == 'n') |
| { |
| return len - 3; |
| } |
| |
| if (StemmerUtil.EndsWith(s, len, "den")) |
| { |
| s[len - 3] = 's'; |
| return len - 2; |
| } |
| |
| if (StemmerUtil.EndsWith(s, len, "ksen")) |
| { |
| s[len - 4] = 's'; |
| return len - 3; |
| } |
| |
| if (StemmerUtil.EndsWith(s, len, "ssa") || StemmerUtil.EndsWith(s, len, "sta") || StemmerUtil.EndsWith(s, len, "lla") || StemmerUtil.EndsWith(s, len, "lta") || StemmerUtil.EndsWith(s, len, "tta") || StemmerUtil.EndsWith(s, len, "ksi") || StemmerUtil.EndsWith(s, len, "lle")) |
| { |
| return len - 3; |
| } |
| } |
| |
| if (len > 5) |
| { |
| if (StemmerUtil.EndsWith(s, len, "na") || StemmerUtil.EndsWith(s, len, "ne")) |
| { |
| return len - 2; |
| } |
| |
| if (StemmerUtil.EndsWith(s, len, "nei")) |
| { |
| return len - 3; |
| } |
| } |
| |
| if (len > 4) |
| { |
| if (StemmerUtil.EndsWith(s, len, "ja") || StemmerUtil.EndsWith(s, len, "ta")) |
| { |
| return len - 2; |
| } |
| |
| if (s[len - 1] == 'a') |
| { |
| return len - 1; |
| } |
| |
| if (s[len - 1] == 'n' && IsVowel(s[len - 2])) |
| { |
| return len - 2; |
| } |
| |
| if (s[len - 1] == 'n') |
| { |
| return len - 1; |
| } |
| } |
| |
| return len; |
| } |
| |
| private int Norm1(char[] s, int len) |
| { |
| if (len > 5 && StemmerUtil.EndsWith(s, len, "hde")) |
| { |
| s[len - 3] = 'k'; |
| s[len - 2] = 's'; |
| s[len - 1] = 'i'; |
| } |
| |
| if (len > 4) |
| { |
| if (StemmerUtil.EndsWith(s, len, "ei") || StemmerUtil.EndsWith(s, len, "at")) |
| { |
| return len - 2; |
| } |
| } |
| |
| if (len > 3) |
| { |
| switch (s[len - 1]) |
| { |
| case 't': |
| case 's': |
| case 'j': |
| case 'e': |
| case 'a': |
| case 'i': |
| return len - 1; |
| } |
| } |
| |
| return len; |
| } |
| |
| private int Norm2(char[] s, int len) |
| { |
| if (len > 8) |
| { |
| if (s[len - 1] == 'e' || s[len - 1] == 'o' || s[len - 1] == 'u') |
| { |
| len--; |
| } |
| } |
| |
| if (len > 4) |
| { |
| if (s[len - 1] == 'i') |
| { |
| len--; |
| } |
| |
| if (len > 4) |
| { |
| char ch = s[0]; |
| for (int i = 1; i < len; i++) |
| { |
| if (s[i] == ch && (ch == 'k' || ch == 'p' || ch == 't')) |
| { |
| len = StemmerUtil.Delete(s, i--, len); |
| } |
| else |
| { |
| ch = s[i]; |
| } |
| } |
| } |
| } |
| |
| return len; |
| } |
| |
| private bool IsVowel(char ch) |
| { |
| switch (ch) |
| { |
| case 'a': |
| case 'e': |
| case 'i': |
| case 'o': |
| case 'u': |
| case 'y': |
| return true; |
| default: |
| return false; |
| } |
| } |
| } |
| } |