org.apache.lucene.analysis.nl.DutchAnalyzer Maven / Gradle / Ivy
package org.apache.lucene.analysis.nl;
/**
* 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.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.File;
import java.io.IOException;
import java.io.Reader;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Set;
import java.util.Map;
/**
* {@link Analyzer} for Dutch language.
*
* Supports an external list of stopwords (words that
* will not be indexed at all), an external list of exclusions (word that will
* not be stemmed, but indexed) and an external list of word-stem pairs that overrule
* the algorithm (dictionary stemming).
* A default set of stopwords is used unless an alternative list is specified, but the
* exclusion list is empty by default.
*
*
* NOTE: This class uses the same {@link Version}
* dependent settings as {@link StandardAnalyzer}.
*/
public class DutchAnalyzer extends Analyzer {
/**
* List of typical Dutch stopwords.
* @deprecated use {@link #getDefaultStopSet()} instead
*/
public final static String[] DUTCH_STOP_WORDS =
{
"de", "en", "van", "ik", "te", "dat", "die", "in", "een",
"hij", "het", "niet", "zijn", "is", "was", "op", "aan", "met", "als", "voor", "had",
"er", "maar", "om", "hem", "dan", "zou", "of", "wat", "mijn", "men", "dit", "zo",
"door", "over", "ze", "zich", "bij", "ook", "tot", "je", "mij", "uit", "der", "daar",
"haar", "naar", "heb", "hoe", "heeft", "hebben", "deze", "u", "want", "nog", "zal",
"me", "zij", "nu", "ge", "geen", "omdat", "iets", "worden", "toch", "al", "waren",
"veel", "meer", "doen", "toen", "moet", "ben", "zonder", "kan", "hun", "dus",
"alles", "onder", "ja", "eens", "hier", "wie", "werd", "altijd", "doch", "wordt",
"wezen", "kunnen", "ons", "zelf", "tegen", "na", "reeds", "wil", "kon", "niets",
"uw", "iemand", "geweest", "andere"
};
/**
* Returns an unmodifiable instance of the default stop-words set.
* @return an unmodifiable instance of the default stop-words set.
*/
public static Set getDefaultStopSet(){
return DefaultSetHolder.DEFAULT_STOP_SET;
}
private static class DefaultSetHolder {
static final Set DEFAULT_STOP_SET = CharArraySet
.unmodifiableSet(new CharArraySet(Arrays.asList(DUTCH_STOP_WORDS),
false));
}
/**
* Contains the stopwords used with the StopFilter.
*/
private final Set stoptable;
/**
* Contains words that should be indexed but not stemmed.
*/
private Set excltable = Collections.emptySet();
private Map stemdict = new HashMap();
private final Version matchVersion;
/**
* Builds an analyzer with the default stop words ({@link #DUTCH_STOP_WORDS})
* and a few default entries for the stem exclusion table.
*
*/
public DutchAnalyzer(Version matchVersion) {
this(matchVersion, DefaultSetHolder.DEFAULT_STOP_SET);
stemdict.put("fiets", "fiets"); //otherwise fiet
stemdict.put("bromfiets", "bromfiets"); //otherwise bromfiet
stemdict.put("ei", "eier");
stemdict.put("kind", "kinder");
}
public DutchAnalyzer(Version matchVersion, Set stopwords){
this(matchVersion, stopwords, CharArraySet.EMPTY_SET);
}
public DutchAnalyzer(Version matchVersion, Set stopwords, Set stemExclusionTable){
stoptable = CharArraySet.unmodifiableSet(CharArraySet.copy(stopwords));
excltable = CharArraySet.unmodifiableSet(CharArraySet.copy(stemExclusionTable));
this.matchVersion = matchVersion;
setOverridesTokenStreamMethod(DutchAnalyzer.class);
}
/**
* Builds an analyzer with the given stop words.
*
* @param matchVersion
* @param stopwords
* @deprecated use {@link #DutchAnalyzer(Version, Set)} instead
*/
public DutchAnalyzer(Version matchVersion, String... stopwords) {
this(matchVersion, StopFilter.makeStopSet(stopwords));
}
/**
* Builds an analyzer with the given stop words.
*
* @param stopwords
* @deprecated use {@link #DutchAnalyzer(Version, Set)} instead
*/
public DutchAnalyzer(Version matchVersion, HashSet stopwords) {
this(matchVersion, (Set)stopwords);
}
/**
* Builds an analyzer with the given stop words.
*
* @param stopwords
* @deprecated use {@link #DutchAnalyzer(Version, Set)} instead
*/
public DutchAnalyzer(Version matchVersion, File stopwords) {
// this is completely broken!
setOverridesTokenStreamMethod(DutchAnalyzer.class);
try {
stoptable = org.apache.lucene.analysis.WordlistLoader.getWordSet(stopwords);
} catch (IOException e) {
// TODO: throw IOException
throw new RuntimeException(e);
}
this.matchVersion = matchVersion;
}
/**
* Builds an exclusionlist from an array of Strings.
*
* @param exclusionlist
* @deprecated use {@link #DutchAnalyzer(Version, Set, Set)} instead
*/
public void setStemExclusionTable(String... exclusionlist) {
excltable = StopFilter.makeStopSet(exclusionlist);
setPreviousTokenStream(null); // force a new stemmer to be created
}
/**
* Builds an exclusionlist from a Hashtable.
* @deprecated use {@link #DutchAnalyzer(Version, Set, Set)} instead
*/
public void setStemExclusionTable(HashSet exclusionlist) {
excltable = exclusionlist;
setPreviousTokenStream(null); // force a new stemmer to be created
}
/**
* Builds an exclusionlist from the words contained in the given file.
* @deprecated use {@link #DutchAnalyzer(Version, Set, Set)} instead
*/
public void setStemExclusionTable(File exclusionlist) {
try {
excltable = org.apache.lucene.analysis.WordlistLoader.getWordSet(exclusionlist);
setPreviousTokenStream(null); // force a new stemmer to be created
} catch (IOException e) {
// TODO: throw IOException
throw new RuntimeException(e);
}
}
/**
* Reads a stemdictionary file , that overrules the stemming algorithm
* This is a textfile that contains per line
* word\tstem, i.e: two tab seperated words
*/
public void setStemDictionary(File stemdictFile) {
try {
stemdict = WordlistLoader.getStemDict(stemdictFile);
setPreviousTokenStream(null); // force a new stemmer to be created
} catch (IOException e) {
// TODO: throw IOException
throw new RuntimeException(e);
}
}
/**
* 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 StopFilter},
* and {@link DutchStemFilter}
*/
@Override
public TokenStream tokenStream(String fieldName, Reader reader) {
TokenStream result = new StandardTokenizer(matchVersion, reader);
result = new StandardFilter(result);
result = new StopFilter(StopFilter.getEnablePositionIncrementsVersionDefault(matchVersion),
result, stoptable);
result = new DutchStemFilter(result, excltable, stemdict);
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 StopFilter},
* and {@link DutchStemFilter}
*/
@Override
public TokenStream reusableTokenStream(String fieldName, Reader reader)
throws IOException {
if (overridesTokenStreamMethod) {
// LUCENE-1678: force fallback to tokenStream() if we
// have been subclassed and that subclass overrides
// tokenStream but not reusableTokenStream
return tokenStream(fieldName, reader);
}
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 StopFilter(StopFilter.getEnablePositionIncrementsVersionDefault(matchVersion),
streams.result, stoptable);
streams.result = new DutchStemFilter(streams.result, excltable, stemdict);
setPreviousTokenStream(streams);
} else {
streams.source.reset(reader);
}
return streams.result;
}
}