Re: Optimising string handling in application

[Frode Tenneboe <ft@alne.edh.ericsson.se>]

tmoran@acm.org wrote:
> Does this (with its questions answered) do what you want?

Yes. Thank you. However, since I'm calling this all over the place
and need the fixed length types I have reintroduced them to put
the gritty stuff in one place:

   procedure Replace_Callsign_In_Msg
     (Msg             : in out Dpu_Loc_Messages.T_Msg_Data_Str;
      Msg_Length      : in out T_Integer_32;
      Callsign        : in     Dpu_Loc_Messages.T_Msg_Callsign;
      Callsign_Length : in     Positive) is

      Stop_First_String : constant Positive := Ada.Strings.Fixed.Index
        (Source => Msg(1 .. Msg_Length),
         Pattern => "ME001=") + 5;
      Start_Next_String : Positive;

   begin

      if Stop_First_String = 5 then -- "ME001=" not present
         raise Constraint_Error;
      end if;

      Start_Next_String := Ada.Strings.Fixed.Index
        (Source => Msg(Stop_First_String .. Msg_Length),
         Pattern => ";");
      if Start_Next_String = 0 then -- ";" not present
         raise Constraint_Error;
      end if;

      declare
         Dummy : constant String :=
           Msg (1 .. Stop_First_String) &
           Callsign(1 .. Callsign_Length) &
           Msg (Start_Next_String .. Msg_Length);
      begin
         Msg_Length := Dummy'Length;
         Msg (1 .. Msg_Length) := Dummy;
      end;

   end Replace_Callsign_In_Msg;


Better. Could probably be tuned more, but it's also more readable
now. Thanks all.

Follow-up question: Is it safe to asume that strings _allways_
start with 'First = 1 (provided the (sub)type starts with 1) except when 
passing slices where 'First = start_of_slice?


 -Frode

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