org.apache.lucene.analysis.cz.CzechAnalyzer Maven / Gradle / Ivy
package org.apache.lucene.analysis.cz;
/**
* 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.Analyzer;
import org.apache.lucene.analysis.CharArraySet;
import org.apache.lucene.analysis.LowerCaseFilter;
import org.apache.lucene.analysis.StopFilter;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.Tokenizer;
import org.apache.lucene.analysis.WordlistLoader;
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.*;
import java.util.Arrays;
import java.util.HashSet;
import java.util.Set;
import java.util.Collections;
/**
* {@link Analyzer} for Czech 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 CzechAnalyzer extends Analyzer {
/**
* List of typical stopwords.
* @deprecated use {@link #getDefaultStopSet()} instead
*/
// TODO make this private in 3.1
public final static String[] CZECH_STOP_WORDS = {
"a","s","k","o","i","u","v","z","dnes","cz","t\u00edmto","bude\u0161","budem",
"byli","jse\u0161","m\u016fj","sv\u00fdm","ta","tomto","tohle","tuto","tyto",
"jej","zda","pro\u010d","m\u00e1te","tato","kam","tohoto","kdo","kte\u0159\u00ed",
"mi","n\u00e1m","tom","tomuto","m\u00edt","nic","proto","kterou","byla",
"toho","proto\u017ee","asi","ho","na\u0161i","napi\u0161te","re","co\u017e","t\u00edm",
"tak\u017ee","sv\u00fdch","jej\u00ed","sv\u00fdmi","jste","aj","tu","tedy","teto",
"bylo","kde","ke","prav\u00e9","ji","nad","nejsou","\u010di","pod","t\u00e9ma",
"mezi","p\u0159es","ty","pak","v\u00e1m","ani","kdy\u017e","v\u0161ak","neg","jsem",
"tento","\u010dl\u00e1nku","\u010dl\u00e1nky","aby","jsme","p\u0159ed","pta","jejich",
"byl","je\u0161t\u011b","a\u017e","bez","tak\u00e9","pouze","prvn\u00ed","va\u0161e","kter\u00e1",
"n\u00e1s","nov\u00fd","tipy","pokud","m\u016f\u017ee","strana","jeho","sv\u00e9","jin\u00e9",
"zpr\u00e1vy","nov\u00e9","nen\u00ed","v\u00e1s","jen","podle","zde","u\u017e","b\u00fdt","v\u00edce",
"bude","ji\u017e","ne\u017e","kter\u00fd","by","kter\u00e9","co","nebo","ten","tak",
"m\u00e1","p\u0159i","od","po","jsou","jak","dal\u0161\u00ed","ale","si","se","ve",
"to","jako","za","zp\u011bt","ze","do","pro","je","na","atd","atp",
"jakmile","p\u0159i\u010dem\u017e","j\u00e1","on","ona","ono","oni","ony","my","vy",
"j\u00ed","ji","m\u011b","mne","jemu","tomu","t\u011bm","t\u011bmu","n\u011bmu","n\u011bmu\u017e",
"jeho\u017e","j\u00ed\u017e","jeliko\u017e","je\u017e","jako\u017e","na\u010de\u017e",
};
/**
* Returns a set of default Czech-stopwords
* @return a set of default Czech-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(CZECH_STOP_WORDS), false));
}
/**
* Contains the stopwords used with the {@link StopFilter}.
*/
// TODO make this final in 3.1
private Set stoptable;
private final Version matchVersion;
/**
* Builds an analyzer with the default stop words ({@link #CZECH_STOP_WORDS}).
*/
public CzechAnalyzer(Version matchVersion) {
this(matchVersion, DefaultSetHolder.DEFAULT_SET);
}
/**
* Builds an analyzer with the given stop words and stemming exclusion words
*
* @param matchVersion
* lucene compatibility version
* @param stopwords
* a stopword set
*/
public CzechAnalyzer(Version matchVersion, Set stopwords) {
this.matchVersion = matchVersion;
this.stoptable = CharArraySet.unmodifiableSet(CharArraySet.copy(stopwords));
}
/**
* Builds an analyzer with the given stop words.
* @deprecated use {@link #CzechAnalyzer(Version, Set)} instead
*/
public CzechAnalyzer(Version matchVersion, String... stopwords) {
this(matchVersion, StopFilter.makeStopSet( stopwords ));
}
/**
* Builds an analyzer with the given stop words.
*
* @deprecated use {@link #CzechAnalyzer(Version, Set)} instead
*/
public CzechAnalyzer(Version matchVersion, HashSet stopwords) {
this(matchVersion, (Set)stopwords);
}
/**
* Builds an analyzer with the given stop words.
* @deprecated use {@link #CzechAnalyzer(Version, Set)} instead
*/
public CzechAnalyzer(Version matchVersion, File stopwords ) throws IOException {
this(matchVersion, (Set)WordlistLoader.getWordSet( stopwords ));
}
/**
* Loads stopwords hash from resource stream (file, database...).
* @param wordfile File containing the wordlist
* @param encoding Encoding used (win-1250, iso-8859-2, ...), null for default system encoding
* @deprecated use {@link WordlistLoader#getWordSet(Reader, String) }
* and {@link #CzechAnalyzer(Version, Set)} instead
*/
public void loadStopWords( InputStream wordfile, String encoding ) {
setPreviousTokenStream(null); // force a new stopfilter to be created
if ( wordfile == null ) {
stoptable = Collections.emptySet();
return;
}
try {
// clear any previous table (if present)
stoptable = Collections.emptySet();
InputStreamReader isr;
if (encoding == null)
isr = new InputStreamReader(wordfile);
else
isr = new InputStreamReader(wordfile, encoding);
stoptable = WordlistLoader.getWordSet(isr);
} catch ( IOException e ) {
// clear any previous table (if present)
// TODO: throw IOException
stoptable = Collections.emptySet();
}
}
/**
* 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 StandardFilter}, {@link LowerCaseFilter}, and {@link StopFilter}
*/
@Override
public final TokenStream tokenStream( String fieldName, Reader reader ) {
TokenStream result = new StandardTokenizer( matchVersion, reader );
result = new StandardFilter( result );
result = new LowerCaseFilter( result );
result = new StopFilter( StopFilter.getEnablePositionIncrementsVersionDefault(matchVersion),
result, stoptable );
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 StandardFilter}, {@link LowerCaseFilter}, 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 StandardFilter(streams.source);
streams.result = new LowerCaseFilter(streams.result);
streams.result = new StopFilter(StopFilter.getEnablePositionIncrementsVersionDefault(matchVersion),
streams.result, stoptable);
setPreviousTokenStream(streams);
} else {
streams.source.reset(reader);
}
return streams.result;
}
}
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