content: package org.apache.lucene.analysis.el;
  
  /**
   * Copyright 2005 The Apache Software Foundation
   *
   * Licensed 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 org.apache.lucene.analysis.Analyzer;
  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.standard.StandardFilter;
  import org.apache.lucene.analysis.standard.StandardTokenizer;
  import org.apache.lucene.analysis.standard.StandardAnalyzer;  // for javadoc
  import org.apache.lucene.util.Version;
  
  import java.io.IOException;
  import java.io.Reader;
  import java.util.Map;
  import java.util.Set;
  
  /**
   * {@link Analyzer} for the Greek language. 
   * <p>
   * Supports an external list of stopwords (words
   * that will not be indexed at all).
   * A default set of stopwords is used unless an alternative list is specified.
   * </p>
   *
   * <a name="version"/>
   * <p>You must specify the required {@link Version}
   * compatibility when creating GreekAnalyzer:
   * <ul>
   *   <li> As of 3.1, StandardFilter and GreekStemmer are used by default.
   *   <li> As of 2.9, StopFilter preserves position
   *        increments
   * </ul>
   * 
   * <p><b>NOTE</b>: This class uses the same {@link Version}
   * dependent settings as {@link StandardAnalyzer}.</p>
   */
  public final class GreekAnalyzer extends StopwordAnalyzerBase {
    /** File containing default Greek stopwords. */
    public final static String DEFAULT_STOPWORD_FILE = "stopwords.txt";
    
    /**
     * Returns a set of default Greek-stopwords 
     * @return a set of default Greek-stopwords 
     */
    public static final Set<?> getDefaultStopSet(){
      return DefaultSetHolder.DEFAULT_SET;
    }
    
    private static class DefaultSetHolder {
      private static final Set<?> DEFAULT_SET;
      
      static {
        try {
          DEFAULT_SET = loadStopwordSet(false, GreekAnalyzer.class, DEFAULT_STOPWORD_FILE, "#");
        } 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");
        }
      }
    }
    
    /**
     * Builds an analyzer with the default stop words.
     * @param matchVersion Lucene compatibility version,
     *   See <a href="#version">above</a>
     */
    public GreekAnalyzer(Version matchVersion) {
      this(matchVersion, DefaultSetHolder.DEFAULT_SET);
    }
    
    /**
     * Builds an analyzer with the given stop words. 
     * <p>
     * <b>NOTE:</b> The stopwords set should be pre-processed with the logic of 
     * {@link GreekLowerCaseFilter} for best results.
     *  
     * @param matchVersion Lucene compatibility version,
     *   See <a href="#version">above</a>
     * @param stopwords a stopword set
     */
    public GreekAnalyzer(Version matchVersion, Set<?> stopwords) {
      super(matchVersion, stopwords);
    }
    
    /**
     * Builds an analyzer with the given stop words.
     * @param stopwords Array of stopwords to use.
     * @deprecated use {@link #GreekAnalyzer(Version, Set)} instead
     */
    @Deprecated
    public GreekAnalyzer(Version matchVersion, String... stopwords) {
      this(matchVersion, StopFilter.makeStopSet(matchVersion, stopwords));
    }
    
    /**
     * Builds an analyzer with the given stop words.
     * @deprecated use {@link #GreekAnalyzer(Version, Set)} instead
     */
    @Deprecated
    public GreekAnalyzer(Version matchVersion, Map<?,?> stopwords) {
      this(matchVersion, stopwords.keySet());
    }
    
    /**
     * Creates
     * {@link org.apache.lucene.analysis.ReusableAnalyzerBase.TokenStreamComponents}
     * used to tokenize all the text in the provided {@link Reader}.
     * 
     * @return {@link org.apache.lucene.analysis.ReusableAnalyzerBase.TokenStreamComponents}
     *         built from a {@link StandardTokenizer} filtered with
     *         {@link GreekLowerCaseFilter}, {@link StandardFilter},
     *         {@link StopFilter}, and {@link GreekStemFilter}
     */
    @Override
    protected TokenStreamComponents createComponents(String fieldName,
        Reader reader) {
      final Tokenizer source = new StandardTokenizer(matchVersion, reader);
      TokenStream result = new GreekLowerCaseFilter(matchVersion, source);
      if (matchVersion.onOrAfter(Version.LUCENE_31))
        result = new StandardFilter(matchVersion, result);
      result = new StopFilter(matchVersion, result, stopwords);
      if (matchVersion.onOrAfter(Version.LUCENE_31))
        result = new GreekStemFilter(result);
      return new TokenStreamComponents(source, result);
    }
  }
  