package org.apache.lucene.analysis.ja;
/*
* 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 java.io.IOException;
import java.io.Reader;
import java.util.HashSet;
import java.util.Set;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.Tokenizer;
import org.apache.lucene.analysis.cjk.CJKWidthFilter;
import org.apache.lucene.analysis.core.LowerCaseFilter;
import org.apache.lucene.analysis.core.StopFilter;
import org.apache.lucene.analysis.ja.JapaneseTokenizer.Mode;
import org.apache.lucene.analysis.ja.dict.UserDictionary;
import org.apache.lucene.analysis.util.CharArraySet;
import org.apache.lucene.analysis.util.StopwordAnalyzerBase;
import org.apache.lucene.util.Version;
/**
* Analyzer for Japanese that uses morphological analysis.
* @see JapaneseTokenizer
*/
public class JapaneseAnalyzer extends StopwordAnalyzerBase {
private final Mode mode;
private final Set<String> stoptags;
private final UserDictionary userDict;
public JapaneseAnalyzer(Version matchVersion) {
this(matchVersion, null, JapaneseTokenizer.DEFAULT_MODE, DefaultSetHolder.DEFAULT_STOP_SET, DefaultSetHolder.DEFAULT_STOP_TAGS);
}
public JapaneseAnalyzer(Version matchVersion, UserDictionary userDict, Mode mode, CharArraySet stopwords, Set<String> stoptags) {
super(matchVersion, stopwords);
this.userDict = userDict;
this.mode = mode;
this.stoptags = stoptags;
}
public static CharArraySet getDefaultStopSet(){
return DefaultSetHolder.DEFAULT_STOP_SET;
}
public static Set<String> getDefaultStopTags(){
return DefaultSetHolder.DEFAULT_STOP_TAGS;
}
/**
* Atomically loads DEFAULT_STOP_SET, DEFAULT_STOP_TAGS in a lazy fashion once the
* outer class accesses the static final set the first time.
*/
private static class DefaultSetHolder {
static final CharArraySet DEFAULT_STOP_SET;
static final Set<String> DEFAULT_STOP_TAGS;
static {
try {
DEFAULT_STOP_SET = loadStopwordSet(true, JapaneseAnalyzer.class, "stopwords.txt", "#"); // ignore case
final CharArraySet tagset = loadStopwordSet(false, JapaneseAnalyzer.class, "stoptags.txt", "#");
DEFAULT_STOP_TAGS = new HashSet<String>();
for (Object element : tagset) {
char chars[] = (char[]) element;
DEFAULT_STOP_TAGS.add(new String(chars));
}
} 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 or stoptag set");
}
}
}
@Override
protected TokenStreamComponents createComponents(String fieldName, Reader reader) {
Tokenizer tokenizer = new JapaneseTokenizer(reader, userDict, true, mode);
TokenStream stream = new JapaneseBaseFormFilter(tokenizer);
stream = new JapanesePartOfSpeechStopFilter(true, stream, stoptags);
stream = new CJKWidthFilter(stream);
stream = new StopFilter(matchVersion, stream, stopwords);
stream = new JapaneseKatakanaStemFilter(stream);
stream = new LowerCaseFilter(matchVersion, stream);
return new TokenStreamComponents(tokenizer, stream);
}
}