/**
* 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.
*/
package org.apache.solr.analysis;
import java.util.Map;
import java.io.IOException;
import org.apache.lucene.analysis.KeywordMarkerFilter;
import org.apache.lucene.analysis.TokenFilter;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.CharArraySet;
import org.apache.lucene.analysis.snowball.SnowballFilter;
import org.apache.solr.common.ResourceLoader;
import org.apache.solr.util.plugin.ResourceLoaderAware;
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>
*
* @version $Id: SnowballPorterFilterFactory.java 1074243 2011-02-24 18:07:16Z rmuir $
*/
public class SnowballPorterFilterFactory extends BaseTokenFilterFactory implements ResourceLoaderAware {
public static final String PROTECTED_TOKENS = "protected";
private String language = "English";
private Class<?> stemClass;
public void inform(ResourceLoader loader) {
String wordFiles = args.get(PROTECTED_TOKENS);
if (wordFiles != null) {
try {
protectedWords = getWordSet(loader, wordFiles, false);
} catch (IOException e) {
throw new RuntimeException(e);
}
}
}
private CharArraySet protectedWords = null;
@Override
public void init(Map<String, String> args) {
super.init(args);
final String cfgLanguage = args.get("language");
if(cfgLanguage!=null) language = cfgLanguage;
try {
stemClass = Class.forName("org.tartarus.snowball.ext." + language + "Stemmer");
} catch (ClassNotFoundException e) {
throw new RuntimeException("Can't find class for stemmer language " + language, e);
}
}
public TokenFilter create(TokenStream input) {
SnowballProgram program;
try {
program = (SnowballProgram)stemClass.newInstance();
} catch (Exception e) {
throw new RuntimeException("Error instantiating stemmer for language " + language + "from class " +stemClass, e);
}
if (protectedWords != null)
input = new KeywordMarkerFilter(input, protectedWords);
return new SnowballFilter(input, program);
}
}