package org.wikimedia.search.extra.analysis.filters;
   
   import org.apache.lucene.analysis.TokenStream;
   import org.elasticsearch.common.settings.Settings;
   import org.elasticsearch.common.settings.SettingsException;
   import org.elasticsearch.env.Environment;
   import org.elasticsearch.index.IndexSettings;
   import org.elasticsearch.index.analysis.AbstractTokenFilterFactory;
   
  
  /**
   * Factories for the term_frequency token filters.
   */
  public class TermFreqTokenFilterFactory extends AbstractTokenFilterFactory {
      private final char splitChar;
      private final int maxTF;
  
      public TermFreqTokenFilterFactory(IndexSettings indexSettings, Environment environment, String name, Settings settings) {
          super(indexSettings, name, settings);
          maxTF = settings.getAsInt("max_tf", 1000);
          if (maxTF <= 0) {
              throw new SettingsException("[max_tf] must be strictly positive");
          }
          String tmp = settings.get("split_char", "|");
          if (tmp.length() == 1) {
              splitChar = tmp.charAt(0);
          } else {
              throw new SettingsException("[split_char] expects a single char");
          }
      }
  
      @Override
      public TokenStream create(TokenStream tokenStream) {
          return new TermFreqTokenFilter(tokenStream, splitChar, maxTF);
      }
  }