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.CharArraySet;
import org.apache.lucene.analysis.StopFilter;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.Tokenizer;
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.Arrays;
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.
*
*
* NOTE: This class uses the same {@link Version}
* dependent settings as {@link StandardAnalyzer}.
*/
public final class GreekAnalyzer extends Analyzer
{
/**
* List of typical Greek stopwords.
*/
private static final String[] GREEK_STOP_WORDS = {
"ο", "η", "το", "οι", "τα", "του", "τησ", "των", "τον", "την", "και",
"κι", "κ", "ειμαι", "εισαι", "ειναι", "ειμαστε", "ειστε", "στο", "στον",
"στη", "στην", "μα", "αλλα", "απο", "για", "προσ", "με", "σε", "ωσ",
"παρα", "αντι", "κατα", "μετα", "θα", "να", "δε", "δεν", "μη", "μην",
"επι", "ενω", "εαν", "αν", "τοτε", "που", "πωσ", "ποιοσ", "ποια", "ποιο",
"ποιοι", "ποιεσ", "ποιων", "ποιουσ", "αυτοσ", "αυτη", "αυτο", "αυτοι",
"αυτων", "αυτουσ", "αυτεσ", "αυτα", "εκεινοσ", "εκεινη", "εκεινο",
"εκεινοι", "εκεινεσ", "εκεινα", "εκεινων", "εκεινουσ", "οπωσ", "ομωσ",
"ισωσ", "οσο", "οτι"
};
/**
* 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 = CharArraySet.unmodifiableSet(new CharArraySet(
Arrays.asList(GREEK_STOP_WORDS), false));
}
/**
* Contains the stopwords used with the {@link StopFilter}.
*/
private final Set stopSet;
private final Version matchVersion;
public GreekAnalyzer(Version matchVersion) {
this(matchVersion, DefaultSetHolder.DEFAULT_SET);
}
/**
* Builds an analyzer with the given stop words
*
* @param matchVersion
* lucene compatibility version
* @param stopwords
* a stopword set
*/
public GreekAnalyzer(Version matchVersion, Set stopwords) {
stopSet = CharArraySet.unmodifiableSet(CharArraySet.copy(stopwords));
this.matchVersion = matchVersion;
}
/**
* Builds an analyzer with the given stop words.
* @param stopwords Array of stopwords to use.
* @deprecated use {@link #GreekAnalyzer(Version, Set)} instead
*/
public GreekAnalyzer(Version matchVersion, String... stopwords)
{
this(matchVersion, StopFilter.makeStopSet(stopwords));
}
/**
* Builds an analyzer with the given stop words.
* @deprecated use {@link #GreekAnalyzer(Version, Set)} instead
*/
public GreekAnalyzer(Version matchVersion, Map stopwords)
{
this(matchVersion, stopwords.keySet());
}
/**
* Creates a {@link TokenStream} which tokenizes all the text in the provided {@link Reader}.
*
* @return A {@link TokenStream} built from a {@link StandardTokenizer} filtered with
* {@link GreekLowerCaseFilter} and {@link StopFilter}
*/
@Override
public TokenStream tokenStream(String fieldName, Reader reader)
{
TokenStream result = new StandardTokenizer(matchVersion, reader);
result = new GreekLowerCaseFilter(result);
result = new StopFilter(StopFilter.getEnablePositionIncrementsVersionDefault(matchVersion),
result, stopSet);
return result;
}
private class SavedStreams {
Tokenizer source;
TokenStream result;
};
/**
* Returns a (possibly reused) {@link TokenStream} which tokenizes all the text
* in the provided {@link Reader}.
*
* @return A {@link TokenStream} built from a {@link StandardTokenizer} filtered with
* {@link GreekLowerCaseFilter} and {@link StopFilter}
*/
@Override
public TokenStream reusableTokenStream(String fieldName, Reader reader)
throws IOException {
SavedStreams streams = (SavedStreams) getPreviousTokenStream();
if (streams == null) {
streams = new SavedStreams();
streams.source = new StandardTokenizer(matchVersion, reader);
streams.result = new GreekLowerCaseFilter(streams.source);
streams.result = new StopFilter(StopFilter.getEnablePositionIncrementsVersionDefault(matchVersion),
streams.result, stopSet);
setPreviousTokenStream(streams);
} else {
streams.source.reset(reader);
}
return streams.result;
}
}