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Lucene example source code file (ArmenianAnalyzer.java)

This example Lucene source code file (ArmenianAnalyzer.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Lucene tags/keywords

armeniananalyzer, armeniananalyzer, default_stop_set, default_stopword_file, default_stopword_file, io, ioexception, reader, set, set, stopfilter, stopwordanalyzerbase, tokenizer, tokenstreamcomponents, tokenstreamcomponents, util

The Lucene ArmenianAnalyzer.java source code

package org.apache.lucene.analysis.hy;

/**
 * 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.Set;

import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.analysis.LowerCaseFilter;
import org.apache.lucene.analysis.StopFilter;
import org.apache.lucene.analysis.KeywordMarkerFilter;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.Tokenizer;
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.CharArraySet;
import org.apache.lucene.analysis.StopwordAnalyzerBase;
import org.apache.lucene.util.Version;
import org.tartarus.snowball.ext.ArmenianStemmer;

/**
 * {@link Analyzer} for Armenian.
 */
public final class ArmenianAnalyzer extends StopwordAnalyzerBase {
  private final Set<?> stemExclusionSet;
  
  /** File containing default Armenian stopwords. */
  public final static String DEFAULT_STOPWORD_FILE = "stopwords.txt";
  
  /**
   * Returns an unmodifiable instance of the default stop words set.
   * @return 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, 
            ArmenianAnalyzer.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: {@link #DEFAULT_STOPWORD_FILE}.
   */
  public ArmenianAnalyzer(Version matchVersion) {
    this(matchVersion, DefaultSetHolder.DEFAULT_STOP_SET);
  }
  
  /**
   * Builds an analyzer with the given stop words.
   * 
   * @param matchVersion lucene compatibility version
   * @param stopwords a stopword set
   */
  public ArmenianAnalyzer(Version matchVersion, Set<?> stopwords) {
    this(matchVersion, stopwords, CharArraySet.EMPTY_SET);
  }

  /**
   * Builds an analyzer with the given stop words. If a non-empty stem exclusion set is
   * provided this analyzer will add a {@link KeywordMarkerFilter} before
   * stemming.
   * 
   * @param matchVersion lucene compatibility version
   * @param stopwords a stopword set
   * @param stemExclusionSet a set of terms not to be stemmed
   */
  public ArmenianAnalyzer(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 SnowballFilter}.
   */
  @Override
  protected 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 SnowballFilter(result, new ArmenianStemmer());
    return new TokenStreamComponents(source, result);
  }
}

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