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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
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package org.apache.lucene.analysis.br;


import java.io.IOException;
import java.io.Reader;
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;

Analyzer for Brazilian Portuguese language. 

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).

NOTE: This class uses the same Version dependent settings as StandardAnalyzer.
Since:
3.1/**
 * {@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>
 *
 * <p><b>NOTE</b>: This class uses the same {@link org.apache.lucene.util.Version}
 * dependent settings as {@link StandardAnalyzer}.</p>
 *
 * @since 3.1
 */
public final class BrazilianAnalyzer extends StopwordAnalyzerBase {
  
File containing default Brazilian Portuguese stopwords. /** File containing default Brazilian Portuguese stopwords. */
  public final static String DEFAULT_STOPWORD_FILE = "stopwords.txt";
  
  
Returns an unmodifiable instance of the default stop-words set.
Returns:
an unmodifiable instance of the default stop-words set./**
   * 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(BrazilianAnalyzer.class, 
            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 RuntimeException("Unable to load default stopword set");
      }
    }
  }


  
Contains words that should be indexed but not stemmed.
/**
   * Contains words that should be indexed but not stemmed.
   */
  private CharArraySet excltable = CharArraySet.EMPTY_SET;

  
Builds an analyzer with the default stop words (getDefaultStopSet()). /**
   * 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
Params:
stopwords – 
         a stopword 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
Params:
stopwords – 
         a stopword set/**
   * 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 TokenStreamComponents used to tokenize all the text in the provided Reader. 
Returns:
TokenStreamComponents built from a StandardTokenizer filtered with LowerCaseFilter, StopFilter , and BrazilianStemFilter./**
   * 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);
  }
}