package org.apache.lucene.analysis.ru;
/*
* 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.Arrays;
import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.analysis.snowball.SnowballFilter;
import org.apache.lucene.analysis.standard.StandardFilter;
import org.apache.lucene.analysis.standard.StandardTokenizer;
import org.apache.lucene.analysis.util.CharArraySet;
import org.apache.lucene.analysis.util.StopwordAnalyzerBase;
import org.apache.lucene.analysis.util.WordlistLoader;
import org.apache.lucene.analysis.core.LowerCaseFilter;
import org.apache.lucene.analysis.core.StopFilter;
import org.apache.lucene.analysis.miscellaneous.SetKeywordMarkerFilter;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.Tokenizer;
import org.apache.lucene.util.IOUtils;
import org.apache.lucene.util.Version;
/**
* {@link Analyzer} for Russian language.
* <p>
* 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.
* </p>
* <a name="version"/>
* <p>You must specify the required {@link Version}
* compatibility when creating RussianAnalyzer:
* <ul>
* <li> As of 3.1, StandardTokenizer is used, Snowball stemming is done with
* SnowballFilter, and Snowball stopwords are used by default.
* </ul>
*/
public final class RussianAnalyzer extends StopwordAnalyzerBase
{
/**
* List of typical Russian stopwords. (for backwards compatibility)
* @deprecated (3.1) Remove this for LUCENE 5.0
*/
@Deprecated
private static final String[] RUSSIAN_STOP_WORDS_30 = {
"а", "без", "более", "бы", "был", "была", "были", "было", "быть", "в",
"вам", "вас", "весь", "во", "вот", "все", "всего", "всех", "вы", "где",
"да", "даже", "для", "до", "его", "ее", "ей", "ею", "если", "есть",
"еще", "же", "за", "здесь", "и", "из", "или", "им", "их", "к", "как",
"ко", "когда", "кто", "ли", "либо", "мне", "может", "мы", "на", "надо",
"наш", "не", "него", "нее", "нет", "ни", "них", "но", "ну", "о", "об",
"однако", "он", "она", "они", "оно", "от", "очень", "по", "под", "при",
"с", "со", "так", "также", "такой", "там", "те", "тем", "то", "того",
"тоже", "той", "только", "том", "ты", "у", "уже", "хотя", "чего", "чей",
"чем", "что", "чтобы", "чье", "чья", "эта", "эти", "это", "я"
};
/** File containing default Russian stopwords. */
public final static String DEFAULT_STOPWORD_FILE = "russian_stop.txt";
private static class DefaultSetHolder {
/** @deprecated (3.1) remove this for Lucene 5.0 */
@Deprecated
static final CharArraySet DEFAULT_STOP_SET_30 = CharArraySet
.unmodifiableSet(new CharArraySet(Version.LUCENE_CURRENT,
Arrays.asList(RUSSIAN_STOP_WORDS_30), false));
static final CharArraySet DEFAULT_STOP_SET;
static {
try {
DEFAULT_STOP_SET = WordlistLoader.getSnowballWordSet(IOUtils.getDecodingReader(SnowballFilter.class,
DEFAULT_STOPWORD_FILE, IOUtils.CHARSET_UTF_8), Version.LUCENE_CURRENT);
} 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", ex);
}
}
}
private final CharArraySet stemExclusionSet;
/**
* Returns an unmodifiable instance of the default stop-words set.
*
* @return an unmodifiable instance of the default stop-words set.
*/
public static CharArraySet getDefaultStopSet() {
return DefaultSetHolder.DEFAULT_STOP_SET;
}
public RussianAnalyzer(Version matchVersion) {
this(matchVersion,
matchVersion.onOrAfter(Version.LUCENE_31) ? DefaultSetHolder.DEFAULT_STOP_SET
: DefaultSetHolder.DEFAULT_STOP_SET_30);
}
/**
* Builds an analyzer with the given stop words
*
* @param matchVersion
* lucene compatibility version
* @param stopwords
* a stopword set
*/
public RussianAnalyzer(Version matchVersion, CharArraySet stopwords){
this(matchVersion, stopwords, CharArraySet.EMPTY_SET);
}
/**
* Builds an analyzer with the given stop words
*
* @param matchVersion
* lucene compatibility version
* @param stopwords
* a stopword set
* @param stemExclusionSet a set of words not to be stemmed
*/
public RussianAnalyzer(Version matchVersion, CharArraySet stopwords, CharArraySet stemExclusionSet){
super(matchVersion, stopwords);
this.stemExclusionSet = CharArraySet.unmodifiableSet(CharArraySet.copy(matchVersion, stemExclusionSet));
}
/**
* 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 StandardFilter}, {@link LowerCaseFilter}, {@link StopFilter}
* , {@link SetKeywordMarkerFilter} if a stem exclusion set is
* provided, and {@link SnowballFilter}
*/
@Override
protected TokenStreamComponents createComponents(String fieldName,
Reader reader) {
if (matchVersion.onOrAfter(Version.LUCENE_31)) {
final Tokenizer source = new StandardTokenizer(matchVersion, reader);
TokenStream result = new StandardFilter(matchVersion, source);
result = new LowerCaseFilter(matchVersion, result);
result = new StopFilter(matchVersion, result, stopwords);
if (!stemExclusionSet.isEmpty()) result = new SetKeywordMarkerFilter(
result, stemExclusionSet);
result = new SnowballFilter(result, new org.tartarus.snowball.ext.RussianStemmer());
return new TokenStreamComponents(source, result);
} else {
final Tokenizer source = new RussianLetterTokenizer(matchVersion, reader);
TokenStream result = new LowerCaseFilter(matchVersion, source);
result = new StopFilter(matchVersion, result, stopwords);
if (!stemExclusionSet.isEmpty()) result = new SetKeywordMarkerFilter(
result, stemExclusionSet);
result = new SnowballFilter(result, new org.tartarus.snowball.ext.RussianStemmer());
return new TokenStreamComponents(source, result);
}
}
}