module Mail::Received

def _nt_primary
  start_index = index
  if node_cache[:primary].has_key?(index)
    cached = node_cache[:primary][index]
    @index = cached.interval.end if cached
    return cached
  end
  i0, s0 = index, []
  r1 = _nt_name_val_list
  s0 << r1
  if r1
    if has_terminal?(";", false, index)
      r2 = instantiate_node(SyntaxNode,input, index...(index + 1))
      @index += 1
    else
      terminal_parse_failure(";")
      r2 = nil
    end
    s0 << r2
    if r2
      r3 = _nt_date_time
      s0 << r3
    end
  end
  if s0.last
    r0 = instantiate_node(SyntaxNode,input, i0...index, s0)
    r0.extend(Primary0)
  else
    @index = i0
    r0 = nil
  end
  node_cache[:primary][start_index] = r0
  r0
end

def root
  @root ||= :primary
end