protected boolean shift_under_error(){
  return get_action(((Symbol)stack.peek()).parse_state,error_sym()) > 0;
}

protected boolean shift_under_error ( ) { return get_action ( ( ( Symbol ) stack . peek ( ) ) . parse_state , error_sym ( ) ) > 0 ; }
determine if we can shift under the special error symbol out of the state currently on the top of the ( real ) parse stack .
