package org.apache.lucene.analysis.snowball;
/*
* 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.util.Map;
import java.io.IOException;
import org.apache.lucene.analysis.miscellaneous.SetKeywordMarkerFilter;
import org.apache.lucene.analysis.TokenFilter;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.util.CharArraySet;
import org.apache.lucene.analysis.util.ResourceLoader;
import org.apache.lucene.analysis.util.ResourceLoaderAware;
import org.apache.lucene.analysis.util.TokenFilterFactory;
import org.tartarus.snowball.SnowballProgram;
/**
* Factory for {@link SnowballFilter}, with configurable language
* <p>
* Note: Use of the "Lovins" stemmer is not recommended, as it is implemented with reflection.
* <pre class="prettyprint">
* <fieldType name="text_snowballstem" class="solr.TextField" positionIncrementGap="100">
* <analyzer>
* <tokenizer class="solr.StandardTokenizerFactory"/>
* <filter class="solr.LowerCaseFilterFactory"/>
* <filter class="solr.SnowballPorterFilterFactory" protected="protectedkeyword.txt" language="English"/>
* </analyzer>
* </fieldType></pre>
*/
public class SnowballPorterFilterFactory extends TokenFilterFactory implements ResourceLoaderAware {
public static final String PROTECTED_TOKENS = "protected";
private final String language;
private final String wordFiles;
private Class<? extends SnowballProgram> stemClass;
private CharArraySet protectedWords = null;
/** Creates a new SnowballPorterFilterFactory */
public SnowballPorterFilterFactory(Map<String,String> args) {
super(args);
language = get(args, "language", "English");
wordFiles = get(args, PROTECTED_TOKENS);
if (!args.isEmpty()) {
throw new IllegalArgumentException("Unknown parameters: " + args);
}
}
@Override
public void inform(ResourceLoader loader) throws IOException {
String className = "org.tartarus.snowball.ext." + language + "Stemmer";
stemClass = loader.newInstance(className, SnowballProgram.class).getClass();
if (wordFiles != null) {
protectedWords = getWordSet(loader, wordFiles, false);
}
}
@Override
public TokenFilter create(TokenStream input) {
SnowballProgram program;
try {
program = stemClass.newInstance();
} catch (Exception e) {
throw new RuntimeException("Error instantiating stemmer for language " + language + "from class " + stemClass, e);
}
if (protectedWords != null)
input = new SetKeywordMarkerFilter(input, protectedWords);
return new SnowballFilter(input, program);
}
}