org.apache.lucene.analysis.el.GreekAnalyzer Maven / Gradle / Ivy
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.
*
* 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.
*
*
*
* You must specify the required {@link Version}
* compatibility when creating GreekAnalyzer:
*
* - As of 3.1, StandardFilter and GreekStemmer are used by default.
*
- As of 2.9, StopFilter preserves position
* increments
*
*
* NOTE: This class uses the same {@link Version}
* dependent settings as {@link StandardAnalyzer}.
*/
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 above
*/
public GreekAnalyzer(Version matchVersion) {
this(matchVersion, 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 matchVersion Lucene compatibility version,
* See above
* @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);
}
}