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Lucene example source code file (FrenchAnalyzer.java)

This example Lucene source code file (FrenchAnalyzer.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

default_stop_set, deprecated, deprecated, frenchanalyzer, frenchanalyzer, io, ioexception, ioexception, set, set, standardtokenizer, stopfilter, string, tokenizer, tokenstreamcomponents, util

The Lucene FrenchAnalyzer.java source code

package org.apache.lucene.analysis.fr;

/**
 * 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 org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.analysis.CharArraySet;
import org.apache.lucene.analysis.LowerCaseFilter;
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.snowball.SnowballFilter;
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.File;
import java.io.IOException;
import java.io.Reader;
import java.util.Arrays;
import java.util.HashSet;
import java.util.Collections;
import java.util.Map;
import java.util.Set;

/**
 * {@link Analyzer} for French language. 
 * <p>
 * Supports an external list of stopwords (words that
 * will not be indexed at all) and an external list of exclusions (word that will
 * not be stemmed, but indexed).
 * A default set of stopwords is used unless an alternative list is specified, but the
 * exclusion list is empty by default.
 * </p>
 *
 * <a name="version"/>
 * <p>You must specify the required {@link Version}
 * compatibility when creating FrenchAnalyzer:
 * <ul>
 *   <li> As of 3.1, Snowball stemming is done with SnowballFilter, 
 *        LowerCaseFilter is used prior to StopFilter, and ElisionFilter and 
 *        Snowball stopwords are used by default.
 *   <li> As of 2.9, StopFilter preserves position
 *        increments
 * </ul>
 *
 * <p>NOTE: This class uses the same {@link Version}
 * dependent settings as {@link StandardAnalyzer}.</p>
 */
public final class FrenchAnalyzer extends StopwordAnalyzerBase {

  /**
   * Extended list of typical French stopwords.
   * @deprecated use {@link #getDefaultStopSet()} instead
   */
  @Deprecated
  public final static String[] FRENCH_STOP_WORDS = {
    "a", "afin", "ai", "ainsi", "après", "attendu", "au", "aujourd", "auquel", "aussi",
    "autre", "autres", "aux", "auxquelles", "auxquels", "avait", "avant", "avec", "avoir",
    "c", "car", "ce", "ceci", "cela", "celle", "celles", "celui", "cependant", "certain",
    "certaine", "certaines", "certains", "ces", "cet", "cette", "ceux", "chez", "ci",
    "combien", "comme", "comment", "concernant", "contre", "d", "dans", "de", "debout",
    "dedans", "dehors", "delà", "depuis", "derrière", "des", "désormais", "desquelles",
    "desquels", "dessous", "dessus", "devant", "devers", "devra", "divers", "diverse",
    "diverses", "doit", "donc", "dont", "du", "duquel", "durant", "dès", "elle", "elles",
    "en", "entre", "environ", "est", "et", "etc", "etre", "eu", "eux", "excepté", "hormis",
    "hors", "hélas", "hui", "il", "ils", "j", "je", "jusqu", "jusque", "l", "la", "laquelle",
    "le", "lequel", "les", "lesquelles", "lesquels", "leur", "leurs", "lorsque", "lui", "là",
    "ma", "mais", "malgré", "me", "merci", "mes", "mien", "mienne", "miennes", "miens", "moi",
    "moins", "mon", "moyennant", "même", "mêmes", "n", "ne", "ni", "non", "nos", "notre",
    "nous", "néanmoins", "nôtre", "nôtres", "on", "ont", "ou", "outre", "où", "par", "parmi",
    "partant", "pas", "passé", "pendant", "plein", "plus", "plusieurs", "pour", "pourquoi",
    "proche", "près", "puisque", "qu", "quand", "que", "quel", "quelle", "quelles", "quels",
    "qui", "quoi", "quoique", "revoici", "revoilà", "s", "sa", "sans", "sauf", "se", "selon",
    "seront", "ses", "si", "sien", "sienne", "siennes", "siens", "sinon", "soi", "soit",
    "son", "sont", "sous", "suivant", "sur", "ta", "te", "tes", "tien", "tienne", "tiennes",
    "tiens", "toi", "ton", "tous", "tout", "toute", "toutes", "tu", "un", "une", "va", "vers",
    "voici", "voilà", "vos", "votre", "vous", "vu", "vôtre", "vôtres", "y", "à", "ça", "ès",
    "été", "être", "ô"
  };

  /** File containing default French stopwords. */
  public final static String DEFAULT_STOPWORD_FILE = "french_stop.txt";
  
  /**
   * Contains words that should be indexed but not stemmed.
   */
  private Set<?> excltable = Collections.emptySet();

  /**
   * 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;
  }
  
  private static class DefaultSetHolder {
    /** @deprecated remove this in Lucene 5.0 */
    @Deprecated
    static final Set<?> DEFAULT_STOP_SET_30 = CharArraySet
        .unmodifiableSet(new CharArraySet(Version.LUCENE_CURRENT, Arrays.asList(FRENCH_STOP_WORDS),
            false));
    static final Set<?> DEFAULT_STOP_SET;
    static {
      try {
        DEFAULT_STOP_SET = 
          WordlistLoader.getSnowballWordSet(SnowballFilter.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 #getDefaultStopSet}).
   */
  public FrenchAnalyzer(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
   * 
   * @param matchVersion
   *          lucene compatibility version
   * @param stopwords
   *          a stopword set
   */
  public FrenchAnalyzer(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 stemExclutionSet
   *          a stemming exclusion set
   */
  public FrenchAnalyzer(Version matchVersion, Set<?> stopwords,
      Set<?> stemExclutionSet) {
    super(matchVersion, stopwords);
    this.excltable = CharArraySet.unmodifiableSet(CharArraySet
        .copy(matchVersion, stemExclutionSet));
  }
 

  /**
   * Builds an analyzer with the given stop words.
   * @deprecated use {@link #FrenchAnalyzer(Version, Set)} instead
   */
  @Deprecated
  public FrenchAnalyzer(Version matchVersion, String... stopwords) {
    this(matchVersion, StopFilter.makeStopSet(matchVersion, stopwords));
  }

  /**
   * Builds an analyzer with the given stop words.
   * @throws IOException
   * @deprecated use {@link #FrenchAnalyzer(Version, Set)} instead
   */
  @Deprecated
  public FrenchAnalyzer(Version matchVersion, File stopwords) throws IOException {
    this(matchVersion, WordlistLoader.getWordSet(stopwords));
  }

  /**
   * Builds an exclusionlist from an array of Strings.
   * @deprecated use {@link #FrenchAnalyzer(Version, Set, Set)} instead
   */
  @Deprecated
  public void setStemExclusionTable(String... exclusionlist) {
    excltable = StopFilter.makeStopSet(matchVersion, exclusionlist);
    setPreviousTokenStream(null); // force a new stemmer to be created
  }

  /**
   * Builds an exclusionlist from a Map.
   * @deprecated use {@link #FrenchAnalyzer(Version, Set, Set)} instead
   */
  @Deprecated
  public void setStemExclusionTable(Map<?,?> exclusionlist) {
    excltable = new HashSet<Object>(exclusionlist.keySet());
    setPreviousTokenStream(null); // force a new stemmer to be created
  }

  /**
   * Builds an exclusionlist from the words contained in the given file.
   * @throws IOException
   * @deprecated use {@link #FrenchAnalyzer(Version, Set, Set)} instead
   */
  @Deprecated
  public void setStemExclusionTable(File exclusionlist) throws IOException {
    excltable = new HashSet<Object>(WordlistLoader.getWordSet(exclusionlist));
    setPreviousTokenStream(null); // force a new stemmer to be created
  }

  /**
   * 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 ElisionFilter},
   *         {@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 ElisionFilter(matchVersion, result);
      result = new LowerCaseFilter(matchVersion, result);
      result = new StopFilter(matchVersion, result, stopwords);
      if(!excltable.isEmpty())
        result = new KeywordMarkerFilter(result, excltable);
      result = new SnowballFilter(result, new org.tartarus.snowball.ext.FrenchStemmer());
      return new TokenStreamComponents(source, result);
    } else {
      final Tokenizer source = new StandardTokenizer(matchVersion, reader);
      TokenStream result = new StandardFilter(matchVersion, source);
      result = new StopFilter(matchVersion, result, stopwords);
      if(!excltable.isEmpty())
        result = new KeywordMarkerFilter(result, excltable);
      result = new FrenchStemFilter(result);
      // Convert to lowercase after stemming!
      return new TokenStreamComponents(source, new LowerCaseFilter(matchVersion, result));
    }
  }
}


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