/*
* 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.
*/
package org.apache.lucene.analysis.miscellaneous;
import org.apache.lucene.analysis.TokenFilter;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.tokenattributes.CharTermAttribute;
import org.apache.lucene.analysis.util.StemmerUtil;
import java.io.IOException;
/**
* This filter normalize use of the interchangeable Scandinavian characters æÆäÄöÖøØ
* and folded variants (aa, ao, ae, oe and oo) by transforming them to åÅæÆøØ.
* <p>
* It's a semantically less destructive solution than {@link ScandinavianFoldingFilter},
* most useful when a person with a Norwegian or Danish keyboard queries a Swedish index
* and vice versa. This filter does <b>not</b> the common Swedish folds of å and ä to a nor ö to o.
* <p>
* blåbærsyltetøj == blåbärsyltetöj == blaabaarsyltetoej but not blabarsyltetoj
* räksmörgås == ræksmørgås == ræksmörgaos == raeksmoergaas but not raksmorgas
* @see ScandinavianFoldingFilter
*/
public final class ScandinavianNormalizationFilter extends TokenFilter {
public ScandinavianNormalizationFilter(TokenStream input) {
super(input);
}
private final CharTermAttribute charTermAttribute = addAttribute(CharTermAttribute.class);
private static final char AA = '\u00C5'; // Å
private static final char aa = '\u00E5'; // å
private static final char AE = '\u00C6'; // Æ
private static final char ae = '\u00E6'; // æ
private static final char AE_se = '\u00C4'; // Ä
private static final char ae_se = '\u00E4'; // ä
private static final char OE = '\u00D8'; // Ø
private static final char oe = '\u00F8'; // ø
private static final char OE_se = '\u00D6'; // Ö
private static final char oe_se = '\u00F6'; //ö
@Override
public boolean incrementToken() throws IOException {
if (!input.incrementToken()) {
return false;
}
char[] buffer = charTermAttribute.buffer();
int length = charTermAttribute.length();
int i;
for (i = 0; i < length; i++) {
if (buffer[i] == ae_se) {
buffer[i] = ae;
} else if (buffer[i] == AE_se) {
buffer[i] = AE;
} else if (buffer[i] == oe_se) {
buffer[i] = oe;
} else if (buffer[i] == OE_se) {
buffer[i] = OE;
} else if (length - 1 > i) {
if (buffer[i] == 'a' && (buffer[i + 1] == 'a' || buffer[i + 1] == 'o' || buffer[i + 1] == 'A' || buffer[i + 1] == 'O')) {
length = StemmerUtil.delete(buffer, i + 1, length);
buffer[i] = aa;
} else if (buffer[i] == 'A' && (buffer[i + 1] == 'a' || buffer[i + 1] == 'A' || buffer[i + 1] == 'o' || buffer[i + 1] == 'O')) {
length = StemmerUtil.delete(buffer, i + 1, length);
buffer[i] = AA;
} else if (buffer[i] == 'a' && (buffer[i + 1] == 'e' || buffer[i + 1] == 'E')) {
length = StemmerUtil.delete(buffer, i + 1, length);
buffer[i] = ae;
} else if (buffer[i] == 'A' && (buffer[i + 1] == 'e' || buffer[i + 1] == 'E')) {
length = StemmerUtil.delete(buffer, i + 1, length);
buffer[i] = AE;
} else if (buffer[i] == 'o' && (buffer[i + 1] == 'e' || buffer[i + 1] == 'E' || buffer[i + 1] == 'o' || buffer[i + 1] == 'O')) {
length = StemmerUtil.delete(buffer, i + 1, length);
buffer[i] = oe;
} else if (buffer[i] == 'O' && (buffer[i + 1] == 'e' || buffer[i + 1] == 'E' || buffer[i + 1] == 'o' || buffer[i + 1] == 'O')) {
length = StemmerUtil.delete(buffer, i + 1, length);
buffer[i] = OE;
}
}
}
charTermAttribute.setLength(length);
return true;
}
}