import java.io.*;

abstract public class PatternFilter extends FilterReader
{
   public PatternFilter(Reader r)
   {
      super(r);
   }

   abstract protected void test() throws IOException;

   public int read() throws IOException
   {
      // Look ahead in the input stream for a match --
      //   method test() should throw an exception is one
      //   one is found...

      test();

      return in.read();
   }
}