process_command_line Subroutine

   subroutine process_command_line(options, rc)
      type (CommandLineOptions), intent(inout) :: options
      integer, optional, intent(out) :: rc

      integer :: n_args
      integer :: i_arg
      character(len=:), allocatable :: argument
      character(len=:), allocatable :: buffer

      n_args = command_argument_count()

      i_arg = 0
      do
         if (i_arg > n_args) exit

         argument = get_next_argument()

         select case (argument)
         case ('-nc', '--npes_client')
            buffer = get_next_argument()
            _ASSERT(buffer /= '-', "no -")
            read(buffer,*) options%npes_client
         case ('-ns', '--npes_server')
            buffer = get_next_argument()
            _ASSERT(buffer /= '-', "no -")
            read(buffer,*) options%npes_server
         case ('-f1', '--file_1')
            options%file_1 = get_next_argument()
            _ASSERT(options%file_1(1:1) /= '-', "too many ")
         case ('-f2', '--file_2')
            options%file_2 = get_next_argument()
            _ASSERT(options%file_2(1:1) /= '-', "too many -")
         case ('-v', '--var')
            buffer = get_next_argument()
            _ASSERT(buffer(1:1) /= '-', "too many -")
            options%requested_variables = parse_vars(buffer)
         case ('-s', '--server_type')
            options%server_type = get_next_argument()
            _ASSERT(options%server_type /= '-', "too many -")
         case ('-d', '--debug')
            options%debug = .true.
         case default
            ! ignore
         end select

      end do

   contains
      
      function get_next_argument() result(argument)
         character(len=:), allocatable :: argument
         
         integer :: length
         
         i_arg = i_arg + 1
         
         call get_command_argument(i_arg, length=length)
         allocate(character(len=length) :: argument)
         call get_command_argument(i_arg, value=argument)
         
      end function get_next_argument

      function parse_vars(buffer) result(vars)
         type (StringVector) :: vars
         character(len=*), intent(in) :: buffer

         integer :: idx
         character(len=1), parameter :: COMMA = ','
         character(len=:), allocatable :: string

         string = buffer // COMMA
         do
            if (len(string) == 0) exit
            idx = index(string,COMMA)
            call vars%push_back(string(1:idx-1))
            string = string(idx+1:)
         end do

      end function parse_vars


   end subroutine process_command_line