package org.apache.lucene.analysis.snowball;
/**
* 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.*;
import org.apache.lucene.analysis.en.EnglishPossessiveFilter;
import org.apache.lucene.analysis.standard.*;
import org.apache.lucene.analysis.tr.TurkishLowerCaseFilter;
import org.apache.lucene.util.Version;
import java.io.IOException;
import java.io.Reader;
import java.util.Set;
/** Filters {@link StandardTokenizer} with {@link StandardFilter}, {@link
* LowerCaseFilter}, {@link StopFilter} and {@link SnowballFilter}.
*
* Available stemmers are listed in org.tartarus.snowball.ext. The name of a
* stemmer is the part of the class name before "Stemmer", e.g., the stemmer in
* {@link org.tartarus.snowball.ext.EnglishStemmer} is named "English".
*
* <p><b>NOTE</b>: This class uses the same {@link Version}
* dependent settings as {@link StandardAnalyzer}, with the following addition:
* <ul>
* <li> As of 3.1, uses {@link TurkishLowerCaseFilter} for Turkish language.
* </ul>
* </p>
* @deprecated Use the language-specific analyzer in contrib/analyzers instead.
* This analyzer will be removed in Lucene 5.0
*/
@Deprecated
public final class SnowballAnalyzer extends Analyzer {
private String name;
private Set<?> stopSet;
private final Version matchVersion;
/** Builds the named analyzer with no stop words. */
public SnowballAnalyzer(Version matchVersion, String name) {
this.name = name;
this.matchVersion = matchVersion;
}
/**
* Builds the named analyzer with the given stop words.
* @deprecated Use {@link #SnowballAnalyzer(Version, String, Set)} instead.
*/
@Deprecated
public SnowballAnalyzer(Version matchVersion, String name, String[] stopWords) {
this(matchVersion, name);
stopSet = StopFilter.makeStopSet(matchVersion, stopWords);
}
/** Builds the named analyzer with the given stop words. */
public SnowballAnalyzer(Version matchVersion, String name, Set<?> stopWords) {
this(matchVersion, name);
stopSet = CharArraySet.unmodifiableSet(CharArraySet.copy(matchVersion,
stopWords));
}
/** Constructs a {@link StandardTokenizer} filtered by a {@link
StandardFilter}, a {@link LowerCaseFilter}, a {@link StopFilter},
and a {@link SnowballFilter} */
@Override
public TokenStream tokenStream(String fieldName, Reader reader) {
TokenStream result = new StandardTokenizer(matchVersion, reader);
result = new StandardFilter(matchVersion, result);
// remove the possessive 's for english stemmers
if (matchVersion.onOrAfter(Version.LUCENE_31) &&
(name.equals("English") || name.equals("Porter") || name.equals("Lovins")))
result = new EnglishPossessiveFilter(result);
// Use a special lowercase filter for turkish, the stemmer expects it.
if (matchVersion.onOrAfter(Version.LUCENE_31) && name.equals("Turkish"))
result = new TurkishLowerCaseFilter(result);
else
result = new LowerCaseFilter(matchVersion, result);
if (stopSet != null)
result = new StopFilter(matchVersion,
result, stopSet);
result = new SnowballFilter(result, name);
return result;
}
private class SavedStreams {
Tokenizer source;
TokenStream result;
}
/** Returns a (possibly reused) {@link StandardTokenizer} filtered by a
* {@link StandardFilter}, a {@link LowerCaseFilter},
* a {@link StopFilter}, and a {@link SnowballFilter} */
@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 StandardFilter(matchVersion, streams.source);
// Use a special lowercase filter for turkish, the stemmer expects it.
if (matchVersion.onOrAfter(Version.LUCENE_31) && name.equals("Turkish"))
streams.result = new TurkishLowerCaseFilter(streams.result);
else
streams.result = new LowerCaseFilter(matchVersion, streams.result);
if (stopSet != null)
streams.result = new StopFilter(matchVersion,
streams.result, stopSet);
streams.result = new SnowballFilter(streams.result, name);
setPreviousTokenStream(streams);
} else {
streams.source.reset(reader);
}
return streams.result;
}
}