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-- CC54003.A
--
-- Grant of Unlimited Rights
--
-- Under contracts F33600-87-D-0337, F33600-84-D-0280, MDA903-79-C-0687,
-- F08630-91-C-0015, and DCA100-97-D-0025, the U.S. Government obtained
-- unlimited rights in the software and documentation contained herein.
-- Unlimited rights are defined in DFAR 252.227-7013(a)(19). By making
-- this public release, the Government intends to confer upon all
-- recipients unlimited rights equal to those held by the Government.
-- These rights include rights to use, duplicate, release or disclose the
-- released technical data and computer software in whole or in part, in
-- any manner and for any purpose whatsoever, and to have or permit others
-- to do so.
--
-- DISCLAIMER
--
-- ALL MATERIALS OR INFORMATION HEREIN RELEASED, MADE AVAILABLE OR
-- DISCLOSED ARE AS IS. THE GOVERNMENT MAKES NO EXPRESS OR IMPLIED
-- WARRANTY AS TO ANY MATTER WHATSOEVER, INCLUDING THE CONDITIONS OF THE
-- SOFTWARE, DOCUMENTATION OR OTHER INFORMATION RELEASED, MADE AVAILABLE
-- OR DISCLOSED, OR THE OWNERSHIP, MERCHANTABILITY, OR FITNESS FOR A
-- PARTICULAR PURPOSE OF SAID MATERIAL.
--*
--
-- OBJECTIVE:
-- Check that a general access-to-subprogram type may be passed as an
-- actual to a generic formal access-to-subprogram type. Check that
-- designated subprograms may be called by dereferencing the access
-- values.
--
-- TEST DESCRIPTION:
-- The generic implements a stack of access-to-subprogram objects as an
-- array. The profile of the access-to-subprogram formal corresponds to
-- a function which accepts a parameter of some type and returns an
-- object of the same type.
--
-- For this test, the functions for which access values will be pushed
-- onto the stack accept a parameter of type access-to-string, lengthen
-- the pointed-to string, then return an access object pointing to this
-- lengthened string.
--
-- The instance declares a function Execute_Stack which executes each
-- subprogram on the stack in sequence. This function accepts some initial
-- access-to-string, then returns an access object pointing to the
-- lengthened string resulting from the execution of the stacked
-- subprograms. Access-to-string objects are used rather than strings
-- themselves because the initial string "grows" during each iteration.
--
--
-- CHANGE HISTORY:
-- 06 Dec 94 SAIC ACVC 2.0
-- 10 Apr 96 SAIC ACVC 2.1: Added pragma Elaborate to context clause
-- preceding CC54003_2.
--
--!
generic
Size : in Positive;
type Item_Type (<>) is private;
type Item_Ptr is access Item_Type;
type Function_Ptr is access function (Item : Item_Ptr)
return Item_Ptr;
package CC54003_0 is -- Generic stack of pointers.
type Stack_Type is private;
procedure Push (Stack : in out Stack_Type;
Func_Ptr : in Function_Ptr);
function Execute_Stack (Stack : Stack_Type;
Initial_Input : Item_Ptr) return Item_Ptr;
-- ... Other operations.
private
subtype Index is Positive range 1 .. (Size + 1);
type Stack_Type is array (Index) of Function_Ptr; -- Last slot unused.
Top : Index := 1; -- Top refers to the next available slot.
end CC54003_0;
--===================================================================--
package body CC54003_0 is
procedure Push (Stack : in out Stack_Type;
Func_Ptr : in Function_Ptr) is
begin
Stack(Top) := Func_Ptr;
Top := Top + 1; -- Artificial: no Constraint_Error protection.
end Push;
-- Call each subprogram on the stack in sequence. For the first call, pass
-- Initial_Input. For succeeding calls, pass the result of the previous
-- call.
function Execute_Stack (Stack : Stack_Type;
Initial_Input : Item_Ptr) return Item_Ptr is
Result : Item_Ptr := Initial_Input;
begin
for I in reverse Index'First .. (Top - 1) loop -- Artificial: no C_E
Result := Stack(I)(Result); -- protection.
end loop;
return Result;
end Execute_Stack;
end CC54003_0;
--===================================================================--
package CC54003_1 is
subtype Message is String;
type Message_Ptr is access Message;
function Add_Prefix (Msg_Ptr : Message_Ptr) return Message_Ptr;
function Add_Suffix (Msg_Ptr : Message_Ptr) return Message_Ptr;
-- ...Other operations.
end CC54003_1;
--===================================================================--
package body CC54003_1 is
function Add_Prefix (Msg_Ptr : Message_Ptr) return Message_Ptr is
Sender : constant String := "Dummy: "; -- Artificial; in a real
-- application Sender might
New_Msg : Message := Sender & Msg_Ptr.all; -- be a call to a function.
begin
return new Message'(New_Msg);
end Add_Prefix;
function Add_Suffix (Msg_Ptr : Message_Ptr) return Message_Ptr is
Time : constant String := " (12:03pm)"; -- Artificial; in a real
-- application Time might be a
New_Msg : Message := Msg_Ptr.all & Time; -- be a call to a function.
begin
return new Message'(New_Msg);
end Add_Suffix;
end CC54003_1;
--===================================================================--
with CC54003_0; -- Generic stack of pointers.
pragma Elaborate (CC54003_0);
with CC54003_1; -- Message abstraction.
package CC54003_2 is
type Operation_Ptr is access function (Msg_Ptr : CC54003_1.Message_Ptr)
return CC54003_1.Message_Ptr;
Maximum_Ops : constant := 4; -- Arbitrary.
package Stack_of_Ops is new CC54003_0
(Item_Type => CC54003_1.Message,
Item_Ptr => CC54003_1.Message_Ptr,
Function_Ptr => Operation_Ptr,
Size => Maximum_Ops);
Operation_Stack : Stack_Of_Ops.Stack_Type;
procedure Create_Operation_Stack;
end CC54003_2;
--===================================================================--
package body CC54003_2 is
procedure Create_Operation_Stack is
begin
Stack_Of_Ops.Push (Operation_Stack, CC54003_1.Add_Prefix'Access);
Stack_Of_Ops.Push (Operation_Stack, CC54003_1.Add_Suffix'Access);
end Create_Operation_Stack;
end CC54003_2;
--===================================================================--
with CC54003_1; -- Message abstraction.
with CC54003_2; -- Message-operation stack.
with Report;
procedure CC54003 is
package Msg_Ops renames CC54003_2.Stack_Of_Ops;
Msg : CC54003_1.Message_Ptr := new CC54003_1.Message'("Hello there");
Expected : CC54003_1.Message := "Dummy: Hello there (12:03pm)";
begin
Report.Test ("CC54003", "Check that a general access-to-subprogram type " &
"may be passed as an actual to a generic formal " &
"access-to-subprogram type");
CC54003_2.Create_Operation_Stack;
declare
Actual : CC54003_1.Message_Ptr :=
Msg_Ops.Execute_Stack (CC54003_2.Operation_Stack, Msg);
begin
if Actual.all /= Expected then
Report.Failed ("Wrong result from dereferenced subprogram execution");
end if;
end;
Report.Result;
end CC54003;
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