The Unsorted BBS Collection/thegreatunsorted.tar/thegreatunsorted/programming/misc_programming/ADAUTIL/SCAN_COM.ADA

Text File | 1990-06-28 | 1.3 KB | 58 lines

-- This example accepts command lines of the form:
--
--      prog [-a] [-b] [arg] ...
--
-- where "prog" is the name of the program, "-a" and
-- "-b" are legal options, and "arg" is some optional
-- argument.
--
with text_handler;      use text_handler;
with text_io;           use text_io;
with arg;
procedure scan_com is
  this: text(127);
  unrecognized_option: exception;
  illegal_argument: exception;
begin
  for i in 2..arg.count loop

    set(this, arg.data(i));
      -- convert string argument to text object.

    if not empty(this) then
      if value(this)(1) = '-' then
    if length(this) < 2 then
      raise illegal_argument;
        -- argument was just '-' alone.
    end if;
    case value(this)(2) is
      when 'a' =>
        put_line("-a recognized");
      when 'b' =>
        put_line("-b recognized");
      when others =>
        raise unrecognized_option;
          -- argument wasn't "-a" or "-b".
    end case;
      else
    put_line("argument """ & value(this) &
            """ recognized");
      -- argument didn't start with '-'.
      end if;
    else
      raise illegal_argument;
    -- argument was empty somehow.
    end if;

  end loop;

exception
  when illegal_argument =>
    put_line("Illegal argument");

  when unrecognized_option =>
    put_line("Unrecognized option: '" &
        value(this) & ''');

end scan_com;