--- /dev/null
+package org.apache.lucene.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.
+ */
+
+import static org.apache.lucene.analysis.util.StemmerUtil.*;
+
+/**
+ * Light Stemmer for Finnish.
+ * <p>
+ * This stemmer implements the algorithm described in:
+ * <i>Report on CLEF-2003 Monolingual Tracks</i>
+ * Jacques Savoy
+ */
+public class FinnishLightStemmer {
+
+ public 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 (endsWith(s, len, "kin"))
+ return step1(s, len-3);
+ if (endsWith(s, len, "ko"))
+ return step1(s, len-2);
+ }
+
+ if (len > 11) {
+ if (endsWith(s, len, "dellinen"))
+ return len-8;
+ if (endsWith(s, len, "dellisuus"))
+ return len-9;
+ }
+ return len;
+ }
+
+ private int step2(char s[], int len) {
+ if (len > 5) {
+ if (endsWith(s, len, "lla")
+ || endsWith(s, len, "tse")
+ || endsWith(s, len, "sti"))
+ return len-3;
+
+ if (endsWith(s, len, "ni"))
+ return len-2;
+
+ if (endsWith(s, len, "aa"))
+ return len-1; // aa -> a
+ }
+
+ return len;
+ }
+
+ private int step3(char s[], int len) {
+ if (len > 8) {
+ if (endsWith(s, len, "nnen")) {
+ s[len-4] = 's';
+ return len-3;
+ }
+
+ if (endsWith(s, len, "ntena")) {
+ s[len-5] = 's';
+ return len-4;
+ }
+
+ if (endsWith(s, len, "tten"))
+ return len-4;
+
+ if (endsWith(s, len, "eiden"))
+ return len-5;
+ }
+
+ if (len > 6) {
+ if (endsWith(s, len, "neen")
+ || endsWith(s, len, "niin")
+ || endsWith(s, len, "seen")
+ || endsWith(s, len, "teen")
+ || endsWith(s, len, "inen"))
+ return len-4;
+
+ if (s[len-3] == 'h' && isVowel(s[len-2]) && s[len-1] == 'n')
+ return len-3;
+
+ if (endsWith(s, len, "den")) {
+ s[len-3] = 's';
+ return len-2;
+ }
+
+ if (endsWith(s, len, "ksen")) {
+ s[len-4] = 's';
+ return len-3;
+ }
+
+ if (endsWith(s, len, "ssa")
+ || endsWith(s, len, "sta")
+ || endsWith(s, len, "lla")
+ || endsWith(s, len, "lta")
+ || endsWith(s, len, "tta")
+ || endsWith(s, len, "ksi")
+ || endsWith(s, len, "lle"))
+ return len-3;
+ }
+
+ if (len > 5) {
+ if (endsWith(s, len, "na")
+ || endsWith(s, len, "ne"))
+ return len-2;
+
+ if (endsWith(s, len, "nei"))
+ return len-3;
+ }
+
+ if (len > 4) {
+ if (endsWith(s, len, "ja")
+ || 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 && endsWith(s, len, "hde")) {
+ s[len-3] = 'k';
+ s[len-2] = 's';
+ s[len-1] = 'i';
+ }
+
+ if (len > 4) {
+ if (endsWith(s, len, "ei") || 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 = delete(s, i--, len);
+ else
+ ch = s[i];
+ }
+ }
+ }
+
+ return len;
+ }
+
+ private boolean isVowel(char ch) {
+ switch(ch) {
+ case 'a':
+ case 'e':
+ case 'i':
+ case 'o':
+ case 'u':
+ case 'y': return true;
+ default: return false;
+ }
+ }
+}
fnp / pylucene.git / blobdiff