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CustomizedIndonesianAnalyzer.java
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CustomizedIndonesianAnalyzer.java
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import org.apache.lucene.analysis.id.*;
import java.io.IOException;
import java.io.Reader;
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.analysis.standard.StandardFilter;
import org.apache.lucene.analysis.standard.StandardTokenizer;
import org.apache.lucene.analysis.standard.std40.StandardTokenizer40;
import org.apache.lucene.analysis.util.CharArraySet;
import org.apache.lucene.analysis.util.StopwordAnalyzerBase;
import org.apache.lucene.util.Version;
/**
* CustomizedIndonesianAnalyzer if you want to customized the analyzer with or
* without stopword removal and stemming process
* Modified from org.apache.lucene.analysis.core.id.IndonesianAnalyzer
* @author Remmy Zen
* @version 1.0 2016-03-20
*/
public class CustomizedIndonesianAnalyzer extends StopwordAnalyzerBase {
private boolean useStemmer;
private boolean useStopword;
/** File containing default Indonesian stopwords. */
public final static String DEFAULT_STOPWORD_FILE = "stopwords.txt";
/**
* 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;
}
/**
* Atomically loads the DEFAULT_STOP_SET 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 {
try {
DEFAULT_STOP_SET = loadStopwordSet(false,
IndonesianAnalyzer.class, DEFAULT_STOPWORD_FILE, "#");
} 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");
}
}
}
private final CharArraySet stemExclusionSet;
/**
* Builds an analyzer with the default stop words:
* {@link #DEFAULT_STOPWORD_FILE}.
*/
public CustomizedIndonesianAnalyzer() {
this(DefaultSetHolder.DEFAULT_STOP_SET);
}
/**
* Builds an analyzer with the given stop words
*
* @param stopwords
* a stopword set
*/
public CustomizedIndonesianAnalyzer(CharArraySet stopwords) {
this(stopwords, CharArraySet.EMPTY_SET);
}
/**
* Builds an analyzer with the given stop word. If a none-empty stem
* exclusion set is provided this analyzer will add a
* {@link SetKeywordMarkerFilter} before {@link IndonesianStemFilter}.
*
* @param stopwords
* a stopword set
* @param stemExclusionSet
* a set of terms not to be stemmed
*/
public CustomizedIndonesianAnalyzer(CharArraySet stopwords,
CharArraySet stemExclusionSet) {
super(stopwords);
this.stemExclusionSet = CharArraySet.unmodifiableSet(CharArraySet
.copy(stemExclusionSet));
}
/**
* CustomizedIndonesianAnalyzer with stemmer and stopword removal option
*
* @param useStemmer
* true if want to use the stemmer, and vice versa
* @param useStopword
* true if want to remove stopword, and vice versa
*/
public CustomizedIndonesianAnalyzer(boolean useStemmer, boolean useStopword) {
this();
this.useStemmer = useStemmer;
this.useStopword = useStopword;
}
/**
* 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 an {@link StandardTokenizer} filtered with
* {@link StandardFilter}, {@link LowerCaseFilter},
* {@link StopFilter}, {@link SetKeywordMarkerFilter} if a stem
* exclusion set is provided and {@link IndonesianStemFilter}.
*/
@Override
protected TokenStreamComponents createComponents(String fieldName) {
final Tokenizer source;
if (getVersion().onOrAfter(Version.LUCENE_4_7_0)) {
source = new StandardTokenizer();
} else {
source = new StandardTokenizer40();
}
TokenStream result = new StandardFilter(source);
result = new LowerCaseFilter(result);
if (useStopword) {
result = new StopFilter(result, stopwords);
}
if (useStemmer) {
if (!stemExclusionSet.isEmpty()) {
result = new SetKeywordMarkerFilter(result, stemExclusionSet);
}
return new TokenStreamComponents(source, new IndonesianStemFilter(
result));
} else {
return new TokenStreamComponents(source, result);
}
}
}