content: package org.apache.lucene.analysis.ru;
  
  /**
   * 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.IOException;
  import java.io.Reader;
  import java.util.Arrays;
  import java.util.Map;
  import java.util.Set;
  
  import org.apache.lucene.analysis.Analyzer;
  import org.apache.lucene.analysis.CharArraySet;
  import org.apache.lucene.analysis.LowerCaseFilter;
  import org.apache.lucene.analysis.snowball.SnowballFilter;
  import org.apache.lucene.analysis.standard.StandardFilter;
  import org.apache.lucene.analysis.standard.StandardTokenizer;
  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.util.IOUtils;
  import org.apache.lucene.util.Version;
  
  /**
   * {@link Analyzer} for Russian 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 RussianAnalyzer:
   * <ul>
   *   <li> As of 3.1, StandardTokenizer is used, Snowball stemming is done with
   *        SnowballFilter, and Snowball stopwords are used by default.
   * </ul>
   */
  public final class RussianAnalyzer extends StopwordAnalyzerBase
  {
      /**
       * List of typical Russian stopwords. (for backwards compatibility)
       * @deprecated Remove this for LUCENE 5.0
       */
      @Deprecated
      private static final String[] RUSSIAN_STOP_WORDS_30 = {
        "а", "без", "более", "бы", "был", "была", "были", "было", "быть", "в",
        "вам", "вас", "весь", "во", "вот", "все", "всего", "всех", "вы", "где", 
        "да", "даже", "для", "до", "его", "ее", "ей", "ею", "если", "есть", 
        "еще", "же", "за", "здесь", "и", "из", "или", "им", "их", "к", "как",
        "ко", "когда", "кто", "ли", "либо", "мне", "может", "мы", "на", "надо", 
        "наш", "не", "него", "нее", "нет", "ни", "них", "но", "ну", "о", "об", 
        "однако", "он", "она", "они", "оно", "от", "очень", "по", "под", "при", 
        "с", "со", "так", "также", "такой", "там", "те", "тем", "то", "того", 
        "тоже", "той", "только", "том", "ты", "у", "уже", "хотя", "чего", "чей", 
        "чем", "что", "чтобы", "чье", "чья", "эта", "эти", "это", "я"
      };
      
      /** File containing default Russian stopwords. */
      public final static String DEFAULT_STOPWORD_FILE = "russian_stop.txt";
      
      private static class DefaultSetHolder {
        /** @deprecated remove this for Lucene 5.0 */
        @Deprecated
        static final Set<?> DEFAULT_STOP_SET_30 = CharArraySet
            .unmodifiableSet(new CharArraySet(Version.LUCENE_CURRENT, 
                Arrays.asList(RUSSIAN_STOP_WORDS_30), false));
        static final Set<?> DEFAULT_STOP_SET;
        
        static {
          try {
            DEFAULT_STOP_SET = WordlistLoader.getSnowballWordSet(IOUtils.getDecodingReader(SnowballFilter.class, 
                DEFAULT_STOPWORD_FILE, IOUtils.CHARSET_UTF_8), Version.LUCENE_CURRENT);
          } 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", ex);
          }
        }
      }
      
      private final Set<?> stemExclusionSet;
      
      /**
       * 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;
      }
  
      public RussianAnalyzer(Version matchVersion) {
        this(matchVersion,
          matchVersion.onOrAfter(Version.LUCENE_31) ? DefaultSetHolder.DEFAULT_STOP_SET
              : DefaultSetHolder.DEFAULT_STOP_SET_30);
      }
    
      /**
       * Builds an analyzer with the given stop words.
       * @deprecated use {@link #RussianAnalyzer(Version, Set)} instead
       */
      @Deprecated
      public RussianAnalyzer(Version matchVersion, String... stopwords) {
        this(matchVersion, StopFilter.makeStopSet(matchVersion, stopwords));
      }
      
      /**
       * Builds an analyzer with the given stop words
       * 
       * @param matchVersion
       *          lucene compatibility version
       * @param stopwords
       *          a stopword set
       */
      public RussianAnalyzer(Version matchVersion, Set<?> stopwords){
        this(matchVersion, stopwords, CharArraySet.EMPTY_SET);
      }
      
      /**
       * Builds an analyzer with the given stop words
       * 
       * @param matchVersion
       *          lucene compatibility version
       * @param stopwords
       *          a stopword set
       * @param stemExclusionSet a set of words not to be stemmed
       */
      public RussianAnalyzer(Version matchVersion, Set<?> stopwords, Set<?> stemExclusionSet){
        super(matchVersion, stopwords);
        this.stemExclusionSet = CharArraySet.unmodifiableSet(CharArraySet.copy(matchVersion, stemExclusionSet));
      }
     
     
      /**
       * Builds an analyzer with the given stop words.
       * TODO: create a Set version of this ctor
       * @deprecated use {@link #RussianAnalyzer(Version, Set)} instead
       */
      @Deprecated
      public RussianAnalyzer(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 StandardFilter}, {@link LowerCaseFilter}, {@link StopFilter}
     *         , {@link KeywordMarkerFilter} if a stem exclusion set is
     *         provided, and {@link SnowballFilter}
     */
      @Override
      protected TokenStreamComponents createComponents(String fieldName,
          Reader reader) {
        if (matchVersion.onOrAfter(Version.LUCENE_31)) {
          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 SnowballFilter(result, new org.tartarus.snowball.ext.RussianStemmer());
          return new TokenStreamComponents(source, result);
        } else {
          final Tokenizer source = new RussianLetterTokenizer(matchVersion, reader);
          TokenStream result = new LowerCaseFilter(matchVersion, source);
          result = new StopFilter(matchVersion, result, stopwords);
          if (!stemExclusionSet.isEmpty()) result = new KeywordMarkerFilter(
            result, stemExclusionSet);
          return new TokenStreamComponents(source, new RussianStemFilter(result));
        }
      }
  }
  