org.apache.lucene.analysis.el.GreekAnalyzer Maven / Gradle / Ivy
/*
* 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.
*/
package org.apache.lucene.analysis.el;
import java.io.IOException;
import java.io.Reader;
import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.analysis.CharArraySet;
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.StandardAnalyzer;
import org.apache.lucene.analysis.standard.StandardTokenizer;
/**
* {@link Analyzer} for the Greek language.
*
* 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.
*
*
* NOTE: This class uses the same {@link org.apache.lucene.util.Version}
* dependent settings as {@link StandardAnalyzer}.
*
* @since 3.1
*/
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 CharArraySet getDefaultStopSet(){
return DefaultSetHolder.DEFAULT_SET;
}
private static class DefaultSetHolder {
private static final CharArraySet 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.
*/
public GreekAnalyzer() {
this(DefaultSetHolder.DEFAULT_SET);
}
/**
* Builds an analyzer with the given stop words.
*
* NOTE: The stopwords set should be pre-processed with the logic of
* {@link GreekLowerCaseFilter} for best results.
*
* @param stopwords a stopword set
*/
public GreekAnalyzer(CharArraySet stopwords) {
super(stopwords);
}
/**
* Creates
* {@link org.apache.lucene.analysis.Analyzer.TokenStreamComponents}
* used to tokenize all the text in the provided {@link Reader}.
*
* @return {@link org.apache.lucene.analysis.Analyzer.TokenStreamComponents}
* built from a {@link StandardTokenizer} filtered with
* {@link GreekLowerCaseFilter},
* {@link StopFilter}, and {@link GreekStemFilter}
*/
@Override
protected TokenStreamComponents createComponents(String fieldName) {
final Tokenizer source = new StandardTokenizer();
TokenStream result = new GreekLowerCaseFilter(source);
result = new StopFilter(result, stopwords);
result = new GreekStemFilter(result);
return new TokenStreamComponents(source, result);
}
@Override
protected TokenStream normalize(String fieldName, TokenStream in) {
return new GreekLowerCaseFilter(in);
}
}