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-------------------------------------------------------------------------------
-- (C) Altran Praxis Limited
-------------------------------------------------------------------------------
--
-- The SPARK toolset is free software; you can redistribute it and/or modify it
-- under terms of the GNU General Public License as published by the Free
-- Software Foundation; either version 3, or (at your option) any later
-- version. The SPARK toolset is distributed in the hope that it will be
-- useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
-- Public License for more details. You should have received a copy of the GNU
-- General Public License distributed with the SPARK toolset; see file
-- COPYING3. If not, go to http://www.gnu.org/licenses for a complete copy of
-- the license.
--
--=============================================================================
separate (Sem.CompUnit)
package body Stack
--# own State is S,
--# Top_Ptr;
is
subtype Index_Range is Integer range 1 .. ExaminerConstants.WfCompilationUnitStackMax;
type Stack_Array is array (Index_Range) of Boolean;
subtype Top_Range is Integer range 0 .. ExaminerConstants.WfCompilationUnitStackMax;
S : Stack_Array;
Top_Ptr : Top_Range;
procedure Init
--# global out S;
--# out Top_Ptr;
--# derives S,
--# Top_Ptr from ;
is
begin
Top_Ptr := 0;
S := Stack_Array'(others => False);
end Init;
procedure Push (X : in Boolean)
--# global in out S;
--# in out Top_Ptr;
--# derives S from *,
--# Top_Ptr,
--# X &
--# Top_Ptr from *;
is
begin
if Top_Ptr < ExaminerConstants.WfCompilationUnitStackMax then
Top_Ptr := Top_Ptr + 1;
S (Top_Ptr) := X;
else
SystemErrors.Fatal_Error (Sys_Err => SystemErrors.Wf_Compilation_Unit_Stack_Overflow,
Msg => "in Stack.Push");
end if;
end Push;
-- return of Item removed, it is never used, pop just clears a stack item
procedure Pop
--# global in out Top_Ptr;
--# derives Top_Ptr from *;
is
begin
if Top_Ptr > 0 then
Top_Ptr := Top_Ptr - 1;
else
SystemErrors.Fatal_Error (Sys_Err => SystemErrors.Wf_Compilation_Unit_Stack_Underflow,
Msg => "in Stack.Pop");
end if;
end Pop;
function Top return Boolean
--# global in S;
--# in Top_Ptr;
is
begin
--# accept Flow, 10, "Expected ineffective assignment to Top_Ptr";
if Top_Ptr = 0 then
--# end accept;
SystemErrors.Fatal_Error (Sys_Err => SystemErrors.Wf_Compilation_Unit_Stack_Underflow,
Msg => "in Stack.Top");
end if;
return S (Top_Ptr);
end Top;
end Stack;
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