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------------------------------------------------------------------------------
-- --
-- GNAT COMPILER COMPONENTS --
-- --
-- S Y S T E M . V A L U E _ I --
-- --
-- B o d y --
-- --
-- Copyright (C) 1992-2023, Free Software Foundation, Inc. --
-- --
-- GNAT is free software; you can redistribute it and/or modify it under --
-- terms of the GNU General Public License as published by the Free Soft- --
-- ware Foundation; either version 3, or (at your option) any later ver- --
-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
-- or FITNESS FOR A PARTICULAR PURPOSE. --
-- --
-- As a special exception under Section 7 of GPL version 3, you are granted --
-- additional permissions described in the GCC Runtime Library Exception, --
-- version 3.1, as published by the Free Software Foundation. --
-- --
-- You should have received a copy of the GNU General Public License and --
-- a copy of the GCC Runtime Library Exception along with this program; --
-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
-- <http://www.gnu.org/licenses/>. --
-- --
-- GNAT was originally developed by the GNAT team at New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc. --
-- --
------------------------------------------------------------------------------
with System.Val_Util; use System.Val_Util;
package body System.Value_I is
-- Ghost code, loop invariants and assertions in this unit are meant for
-- analysis only, not for run-time checking, as it would be too costly
-- otherwise. This is enforced by setting the assertion policy to Ignore.
pragma Assertion_Policy (Ghost => Ignore,
Loop_Invariant => Ignore,
Assert => Ignore,
Assert_And_Cut => Ignore,
Subprogram_Variant => Ignore);
------------------
-- Scan_Integer --
------------------
procedure Scan_Integer
(Str : String;
Ptr : not null access Integer;
Max : Integer;
Res : out Int)
is
procedure Prove_Is_Int_Of_Uns
(Minus : Boolean;
Uval : Uns;
Val : Int)
with Ghost,
Pre => Spec.Uns_Is_Valid_Int (Minus, Uval)
and then
(if Minus and then Uval = Uns (Int'Last) + 1 then Val = Int'First
elsif Minus then Val = -(Int (Uval))
else Val = Int (Uval)),
Post => Spec.Is_Int_Of_Uns (Minus, Uval, Val);
-- Unfold the definition of Is_Int_Of_Uns
procedure Prove_Is_Int_Of_Uns
(Minus : Boolean;
Uval : Uns;
Val : Int)
is null;
Uval : Uns;
-- Unsigned result
Minus : Boolean;
-- Set to True if minus sign is present, otherwise to False
Unused_Start : Positive;
-- Saves location of first non-blank (not used in this case)
Non_Blank : constant Positive :=
First_Non_Space_Ghost (Str, Ptr.all, Max)
with Ghost;
Fst_Num : constant Positive :=
(if Str (Non_Blank) in '+' | '-' then Non_Blank + 1
else Non_Blank)
with Ghost;
begin
Scan_Sign (Str, Ptr, Max, Minus, Unused_Start);
if Str (Ptr.all) not in '0' .. '9' then
Ptr.all := Unused_Start;
Bad_Value (Str);
end if;
Scan_Raw_Unsigned (Str, Ptr, Max, Uval);
pragma Assert
(Uval = U_Spec.Scan_Raw_Unsigned_Ghost (Str, Fst_Num, Max));
-- Deal with overflow cases, and also with largest negative number
if Uval > Uns (Int'Last) then
if Minus and then Uval = Uns (Int'Last) + 1 then
Res := Int'First;
else
Bad_Value (Str);
end if;
-- Negative values
elsif Minus then
Res := -(Int (Uval));
-- Positive values
else
Res := Int (Uval);
end if;
Prove_Is_Int_Of_Uns
(Minus => Str (Non_Blank) = '-',
Uval => Uval,
Val => Res);
end Scan_Integer;
-------------------
-- Value_Integer --
-------------------
function Value_Integer (Str : String) return Int is
begin
-- We have to special case Str'Last = Positive'Last because the normal
-- circuit ends up setting P to Str'Last + 1 which is out of bounds. We
-- deal with this by converting to a subtype which fixes the bounds.
if Str'Last = Positive'Last then
declare
subtype NT is String (1 .. Str'Length);
procedure Prove_Is_Integer_Ghost with
Ghost,
Pre => Str'Length < Natural'Last
and then not Only_Space_Ghost (Str, Str'First, Str'Last)
and then Spec.Is_Integer_Ghost (Spec.Slide_To_1 (Str)),
Post => Spec.Is_Integer_Ghost (NT (Str));
procedure Prove_Is_Integer_Ghost is null;
begin
Prove_Is_Integer_Ghost;
return Value_Integer (NT (Str));
end;
-- Normal case where Str'Last < Positive'Last
else
declare
V : Int;
P : aliased Integer := Str'First;
Non_Blank : constant Positive := First_Non_Space_Ghost
(Str, Str'First, Str'Last)
with Ghost;
Fst_Num : constant Positive :=
(if Str (Non_Blank) in '+' | '-' then Non_Blank + 1
else Non_Blank)
with Ghost;
begin
declare
P_Acc : constant not null access Integer := P'Access;
begin
Scan_Integer (Str, P_Acc, Str'Last, V);
end;
pragma Assert
(P = U_Spec.Raw_Unsigned_Last_Ghost
(Str, Fst_Num, Str'Last));
Scan_Trailing_Blanks (Str, P);
pragma Assert
(Spec.Is_Value_Integer_Ghost (Spec.Slide_If_Necessary (Str), V));
return V;
end;
end if;
end Value_Integer;
end System.Value_I;
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