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BrazilianAnalyzer.java
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BrazilianAnalyzer.java
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/*
* 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.br;
import java.io.IOException;
import java.io.Reader;
import java.io.UncheckedIOException;
import java.nio.charset.StandardCharsets;
import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.analysis.CharArraySet;
import org.apache.lucene.analysis.LowerCaseFilter;
import org.apache.lucene.analysis.StopFilter;
import org.apache.lucene.analysis.StopwordAnalyzerBase;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.Tokenizer;
import org.apache.lucene.analysis.WordlistLoader;
import org.apache.lucene.analysis.miscellaneous.SetKeywordMarkerFilter;
import org.apache.lucene.analysis.standard.StandardAnalyzer;
import org.apache.lucene.analysis.standard.StandardTokenizer;
import org.apache.lucene.util.IOUtils;
/**
* {@link Analyzer} for Brazilian Portuguese language.
*
* <p>Supports an external list of stopwords (words that will not be indexed at all) and an external
* list of exclusions (words that will not be stemmed, but indexed).
*
* <p><b>NOTE</b>: This class uses the same {@link org.apache.lucene.util.Version} dependent
* settings as {@link StandardAnalyzer}.
*
* @since 3.1
*/
public final class BrazilianAnalyzer extends StopwordAnalyzerBase {
/** File containing default Brazilian Portuguese stopwords. */
public static final String DEFAULT_STOPWORD_FILE = "stopwords.txt";
/**
* Returns an unmodifiable instance of the default stop-words set.
*
* @return an unmodifiable instance of the default stop-words set.
*/
public static CharArraySet getDefaultStopSet() {
return DefaultSetHolder.DEFAULT_STOP_SET;
}
private static class DefaultSetHolder {
static final CharArraySet DEFAULT_STOP_SET;
static {
try {
DEFAULT_STOP_SET =
WordlistLoader.getWordSet(
IOUtils.getDecodingReader(
IOUtils.requireResourceNonNull(
BrazilianAnalyzer.class.getResourceAsStream(DEFAULT_STOPWORD_FILE),
DEFAULT_STOPWORD_FILE),
StandardCharsets.UTF_8),
"#");
} catch (IOException ex) {
// default set should always be present as it is part of the
// distribution (JAR)
throw new UncheckedIOException("Unable to load default stopword set", ex);
}
}
}
/** Contains words that should be indexed but not stemmed. */
private CharArraySet excltable = CharArraySet.EMPTY_SET;
/** Builds an analyzer with the default stop words ({@link #getDefaultStopSet()}). */
public BrazilianAnalyzer() {
this(DefaultSetHolder.DEFAULT_STOP_SET);
}
/**
* Builds an analyzer with the given stop words
*
* @param stopwords a stopword set
*/
public BrazilianAnalyzer(CharArraySet stopwords) {
super(stopwords);
}
/**
* Builds an analyzer with the given stop words and stemming exclusion words
*
* @param stopwords a stopword set
*/
public BrazilianAnalyzer(CharArraySet stopwords, CharArraySet stemExclusionSet) {
this(stopwords);
excltable = CharArraySet.unmodifiableSet(CharArraySet.copy(stemExclusionSet));
}
/**
* Creates {@link org.apache.lucene.analysis.Analyzer.TokenStreamComponents} used to tokenize all
* the text in the provided {@link Reader}.
*
* @return {@link org.apache.lucene.analysis.Analyzer.TokenStreamComponents} built from a {@link
* StandardTokenizer} filtered with {@link LowerCaseFilter}, {@link StopFilter}, and {@link
* BrazilianStemFilter}.
*/
@Override
protected TokenStreamComponents createComponents(String fieldName) {
Tokenizer source = new StandardTokenizer();
TokenStream result = new LowerCaseFilter(source);
result = new StopFilter(result, stopwords);
if (excltable != null && !excltable.isEmpty())
result = new SetKeywordMarkerFilter(result, excltable);
return new TokenStreamComponents(source, new BrazilianStemFilter(result));
}
@Override
protected TokenStream normalize(String fieldName, TokenStream in) {
return new LowerCaseFilter(in);
}
}