Re: Bitwise "OR" for ada

[mheaney@ni.net (Matthew Heaney)]

In article <Pine.OSF.3.91.970109130027.809A-100000@osf1.gmu.edu>, Joel Rudy
<jrudy@osf1.gmu.edu> wrote:

>Is there any way to do a bitwise or operation on strings in Ada 83? 
>
>For example =>
>
>clean_String := "AAA";
>template     := "LLL";
>
>result := clean_string or template;
>
>Then result would equal "MMM".

Here is a way to do it.  It does not check that Left and Right are of equal
length.

function "or" (Left, Right : String) return String is

   type Bit_Array is array (Positive range 1 .. Left'Size) of Boolean;
   pragma Pack (Bit_Array);

   subtype Constrained_String is String (Left'Range);

   function To_Bit_Array is 
      new Unchecked_Conversion (Constrained_String, Bit_Array);

   function To_String is
      new Unchecked_Conversion (Bit_Array, Constrained_String);

   Left_As_Bit_Array : constant Bit_Array := 
      To_Bit_Array (Left);

   Right_As_Bit_Array : constant Bit_Array :=
      To_Bit_Array (Right);

   The_Result_As_Bit_Array : constant Bit_Array :=
      Left_As_Bit_Array or Right_As_Bit_Array;

   The_Result : constant Constrained_String :=
      To_String (The_Result_As_Bit_Array);
begin
   return The_Result;
end;

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Matthew Heaney
Software Development Consultant
<mailto:matthew_heaney@acm.org>
(818) 985-1271