package org.wikimedia.search.extra.analysis.turkish;
   
   import java.io.IOException;
   
   import org.apache.lucene.analysis.TokenFilter;
   import org.apache.lucene.analysis.TokenStream;
   import org.apache.lucene.analysis.tokenattributes.CharTermAttribute;
   
   import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
  
  /*
   * Better Apostrophe handling for Turkish.
   *
   * Input is expected to be in lowercase, but with diacritical marks
   */
  @SuppressFBWarnings(value = "EQ_DOESNT_OVERRIDE_EQUALS", justification = "Standard pattern for token filters.")
  public final class BetterApostropheFilter extends TokenFilter {
  
      private final CharTermAttribute termAtt = addAttribute(CharTermAttribute.class);
      private static final BetterApostrophe APOSTROPHE = new BetterApostrophe();
  
      public BetterApostropheFilter(TokenStream input) {
          super(input);
      }
  
      @Override
      public boolean incrementToken() throws IOException {
          if (input.incrementToken()) {
              CharSequence converted = APOSTROPHE.apos(termAtt);
              if (converted != termAtt) {
                  termAtt.setEmpty().append(converted);
              }
              return true;
          }
          return false;
      }
  
  }