namespace Calculator
{
public abstract class ScanBase : AbstractScanner<ValueType,LexLocation> {
}
public class Parser: ShiftReduceParser<ValueType, LexLocation>
{
  static Parser() {
  }
  protected override void Initialize() {
  }
省略
  protected override string TerminalToString(int terminal)
  {
  }
         Parser() : base(null) { }
         public static void Calculate(string input)
         {
            Parser parser = new Parser();
            Scanner scanner = new Scanner();
            scanner.SetSource(input, 0);
            parser.Scanner = scanner;
            parser.Parse();
         }
}
}

         Parser() : base(null) { }
これは何をしてるのですか?