Ada Source code modifications using ASIS(Ada Semantics interface specifications)

Question

i am developing a tool for finding sub type range overflow problems in Ada source code.for this purpose i am using ASIS for finding assignment statements in Ada source code and finding type of the variables on the right side of the assignment expression.now i want to replace the variables(not of record type) of the assignment expression with 'first, 'last values of the variable type in the assignment statement so that i will get compilation error if any range overflow happens.below is an example what i am trying to convey.

procedure Example is
   subtype A_Type is integer 1 .. 10;
   subtype B_Type is integer -5 .. 5;
   subtype C_Type is integer 1 .. 12;

   A : A_Type;
   B : B_Type;
   C : C_Type;
begin
   C := A + B;
end Example;

I want modify C := A + B; with C := A_Type'Last + B_Type'Last in the source code. C := A_Type'Last + B_Type'Last assignment statement will get warning at compile time or Constraint error during run time.

Is it possible do above modifications with ASIS?

Answer 1

For your purpose, you shouldn't rewrite the source text you are processing. You should rather write a new program, which only contains exactly the required declarations and assignments.

So the output should be something like:

with Type_Declarations;

procedure Test_Driver is
begin
   declare
      C : Type_Declarations.C_Type;
   begin
      C := Type_Declarations."+" (Type_Declarations.A_Type'First, Type_Declarations.B_Type'First);
      C := Type_Declarations."+" (Type_Declarations.A_Type'First, Type_Declarations.B_Type'Last);
      C := Type_Declarations."+" (Type_Declarations.A_Type'Last, Type_Declarations.B_Type'First);
      C := Type_Declarations."+" (Type_Declarations.A_Type'Last, Type_Declarations.B_Type'Last);
   end;
end Test_Driver;