content: package org.apache.lucene.analysis.bg;
  
  /**
   * 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.
   */
  
  import java.io.File;
  import java.io.IOException;
  import java.io.Reader;
  import java.util.Set;
  
  import org.apache.lucene.analysis.Analyzer;
  import org.apache.lucene.analysis.LowerCaseFilter;
  import org.apache.lucene.analysis.CharArraySet;
  import org.apache.lucene.analysis.KeywordMarkerFilter;
  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.standard.StandardFilter;
  import org.apache.lucene.analysis.standard.StandardTokenizer;
  import org.apache.lucene.util.Version;
  
  /**
   * {@link Analyzer} for Bulgarian.
   * <p>
   * This analyzer implements light-stemming as specified by: <i> Searching
   * Strategies for the Bulgarian Language </i>
   * http://members.unine.ch/jacques.savoy/Papers/BUIR.pdf
   * <p>
   */
  public final class BulgarianAnalyzer extends StopwordAnalyzerBase {
    
    /**
     * File containing default Bulgarian stopwords.
     * 
     * Default stopword list is from
     * http://members.unine.ch/jacques.savoy/clef/index.html The stopword list is
     * BSD-Licensed.
     */
    public final static String DEFAULT_STOPWORD_FILE = "stopwords.txt";
    
    /**
     * The comment character in the stopwords file. All lines prefixed with this
     * will be ignored
     * @deprecated use {@link WordlistLoader#getWordSet(Reader, String, Version)} directly
     */
    //TODO make this private
    @Deprecated
    public static final String STOPWORDS_COMMENT = "#";
    
    /**
     * Returns an unmodifiable instance of the default stop-words set.
     * 
     * @return an unmodifiable instance of the default stop-words set.
     */
    public static Set<?> getDefaultStopSet() {
      return DefaultSetHolder.DEFAULT_STOP_SET;
    }
    
    /**
     * Atomically loads the DEFAULT_STOP_SET in a lazy fashion once the outer
     * class accesses the static final set the first time.;
     */
    private static class DefaultSetHolder {
      static final Set<?> DEFAULT_STOP_SET;
      
      static {
        try {
          DEFAULT_STOP_SET = loadStopwordSet(false, BulgarianAnalyzer.class, DEFAULT_STOPWORD_FILE, STOPWORDS_COMMENT);
        } 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");
        }
      }
    }
    
    private final Set<?> stemExclusionSet;
     
    /**
     * Builds an analyzer with the default stop words:
     * {@link #DEFAULT_STOPWORD_FILE}.
     */
    public BulgarianAnalyzer(Version matchVersion) {
      this(matchVersion, DefaultSetHolder.DEFAULT_STOP_SET);
    }
    
    /**
     * Builds an analyzer with the given stop words.
     */
    public BulgarianAnalyzer(Version matchVersion, Set<?> stopwords) {
      this(matchVersion, stopwords, CharArraySet.EMPTY_SET);
    }
    
    /**
     * Builds an analyzer with the given stop words and a stem exclusion set.
     * If a stem exclusion set is provided this analyzer will add a {@link KeywordMarkerFilter} 
     * before {@link BulgarianStemFilter}.
     */
    public BulgarianAnalyzer(Version matchVersion, Set<?> stopwords, Set<?> stemExclusionSet) {
      super(matchVersion, stopwords);
      this.stemExclusionSet = CharArraySet.unmodifiableSet(CharArraySet.copy(
          matchVersion, stemExclusionSet));  }
  
    /**
     * Creates a
     * {@link org.apache.lucene.analysis.ReusableAnalyzerBase.TokenStreamComponents}
     * which tokenizes all the text in the provided {@link Reader}.
     * 
     * @return A
     *         {@link org.apache.lucene.analysis.ReusableAnalyzerBase.TokenStreamComponents}
     *         built from an {@link StandardTokenizer} filtered with
     *         {@link StandardFilter}, {@link LowerCaseFilter}, {@link StopFilter}
     *         , {@link KeywordMarkerFilter} if a stem exclusion set is
     *         provided and {@link BulgarianStemFilter}.
     */
    @Override
    public TokenStreamComponents createComponents(String fieldName, Reader reader) {
      final Tokenizer source = new StandardTokenizer(matchVersion, reader);
      TokenStream result = new StandardFilter(matchVersion, source);
      result = new LowerCaseFilter(matchVersion, result);
      result = new StopFilter(matchVersion, result, stopwords);
      if(!stemExclusionSet.isEmpty())
        result = new KeywordMarkerFilter(result, stemExclusionSet);
      result = new BulgarianStemFilter(result);
      return new TokenStreamComponents(source, result);
    }
  }
  