content: /**
   * 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" >
   * &lt;fieldType name="text_snowballstem" class="solr.TextField" positionIncrementGap="100"&gt;
   *   &lt;analyzer&gt;
   *     &lt;tokenizer class="solr.StandardTokenizerFactory"/&gt;
   *     &lt;filter class="solr.LowerCaseFilterFactory"/&gt;
   *     &lt;filter class="solr.SnowballPorterFilterFactory" protected="protectedkeyword.txt" language="English"/&gt;
   *   &lt;/analyzer&gt;
   * &lt;/fieldType&gt;</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);
    }
  }
  
  