package org.apache.lucene.analysis.br;
/**
* Copyright 2004-2005 The Apache Software Foundation
*
* Licensed 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.LowerCaseFilter;
import org.apache.lucene.analysis.StopFilter;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.WordlistLoader;
import org.apache.lucene.analysis.standard.StandardFilter;
import org.apache.lucene.analysis.standard.StandardTokenizer;
import java.io.File;
import java.io.IOException;
import java.io.Reader;
import java.util.Hashtable;
import java.util.HashSet;
import java.util.Set;
/**
* Analyzer for Brazilian language. Supports an external list of stopwords (words that
* will not be indexed at all) and an external list of exclusions (word that will
* not be stemmed, but indexed).
*
* @author João Kramer
*/
public final class BrazilianAnalyzer extends Analyzer {
/**
* List of typical Brazilian stopwords.
*/
public final static String[] BRAZILIAN_STOP_WORDS = {
"a","ainda","alem","ambas","ambos","antes",
"ao","aonde","aos","apos","aquele","aqueles",
"as","assim","com","como","contra","contudo",
"cuja","cujas","cujo","cujos","da","das","de",
"dela","dele","deles","demais","depois","desde",
"desta","deste","dispoe","dispoem","diversa",
"diversas","diversos","do","dos","durante","e",
"ela","elas","ele","eles","em","entao","entre",
"essa","essas","esse","esses","esta","estas",
"este","estes","ha","isso","isto","logo","mais",
"mas","mediante","menos","mesma","mesmas","mesmo",
"mesmos","na","nas","nao","nas","nem","nesse","neste",
"nos","o","os","ou","outra","outras","outro","outros",
"pelas","pelas","pelo","pelos","perante","pois","por",
"porque","portanto","proprio","propios","quais","qual",
"qualquer","quando","quanto","que","quem","quer","se",
"seja","sem","sendo","seu","seus","sob","sobre","sua",
"suas","tal","tambem","teu","teus","toda","todas","todo",
"todos","tua","tuas","tudo","um","uma","umas","uns"};
/**
* Contains the stopwords used with the StopFilter.
*/
private Set stoptable = new HashSet();
/**
* Contains words that should be indexed but not stemmed.
*/
private Set excltable = new HashSet();
/**
* Builds an analyzer with the default stop words ({@link #BRAZILIAN_STOP_WORDS}).
*/
public BrazilianAnalyzer() {
stoptable = StopFilter.makeStopSet( BRAZILIAN_STOP_WORDS );
}
/**
* Builds an analyzer with the given stop words.
*/
public BrazilianAnalyzer( String[] stopwords ) {
stoptable = StopFilter.makeStopSet( stopwords );
}
/**
* Builds an analyzer with the given stop words.
*/
public BrazilianAnalyzer( Hashtable stopwords ) {
stoptable = new HashSet(stopwords.keySet());
}
/**
* Builds an analyzer with the given stop words.
*/
public BrazilianAnalyzer( File stopwords ) throws IOException {
stoptable = WordlistLoader.getWordSet( stopwords );
}
/**
* Builds an exclusionlist from an array of Strings.
*/
public void setStemExclusionTable( String[] exclusionlist ) {
excltable = StopFilter.makeStopSet( exclusionlist );
}
/**
* Builds an exclusionlist from a Hashtable.
*/
public void setStemExclusionTable( Hashtable exclusionlist ) {
excltable = new HashSet(exclusionlist.keySet());
}
/**
* Builds an exclusionlist from the words contained in the given file.
*/
public void setStemExclusionTable( File exclusionlist ) throws IOException {
excltable = WordlistLoader.getWordSet( exclusionlist );
}
/**
* Creates a TokenStream which tokenizes all the text in the provided Reader.
*
* @return A TokenStream build from a StandardTokenizer filtered with
* StandardFilter, StopFilter, GermanStemFilter and LowerCaseFilter.
*/
public final TokenStream tokenStream(String fieldName, Reader reader) {
TokenStream result = new StandardTokenizer( reader );
result = new StandardFilter( result );
result = new StopFilter( result, stoptable );
result = new BrazilianStemFilter( result, excltable );
// Convert to lowercase after stemming!
result = new LowerCaseFilter( result );
return result;
}
}