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--                                                                          --

--                         GNAT COMPILER COMPONENTS                         --

--                                                                          --

--                       S Y S T E M . V A L _ D E C                        --

--                                                                          --

--                                 S p e c                                  --

--                                                                          --

--            Copyright (C) 1992-2009, 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.      --

--                                                                          --

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--  This package contains routines for scanning decimal values where the size

--  of the type is no greater than Standard.Integer'Size, for use in Text_IO.

--  Decimal_IO, and the Value attribute for such decimal types.

package System.Val_Dec is

   pragma Pure;

   function Scan_Decimal

     (Str   : String;

      Ptr   : not null access Integer;

      Max   : Integer;

      Scale : Integer) return Integer;

   --  This function scans the string starting at Str (Ptr.all) for a valid

   --  real literal according to the syntax described in (RM 3.5(43)). The

   --  substring scanned extends no further than Str (Max). There are three

   --  cases for the return:

   --

   --  If a valid real literal is found after scanning past any initial spaces,

   --  then Ptr.all is updated past the last character of the literal (but

   --  trailing spaces are not scanned out). The value returned is the value

   --  Integer'Integer_Value (decimal-literal-value), using the given Scale

   --  to determine this value.

   --

   --  If no valid real literal is found, then Ptr.all points either to an

   --  initial non-digit character, or to Max + 1 if the field is all spaces

   --  and the exception Constraint_Error is raised.

   --

   --  If a syntactically valid integer is scanned, but the value is out of

   --  range, or, in the based case, the base value is out of range or there

   --  is an out of range digit, then Ptr.all points past the integer, and

   --  Constraint_Error is raised.

   --

   --  Note: these rules correspond to the requirements for leaving the

   --  pointer positioned in Text_Io.Get

   --

   --  Note: if Str is null, i.e. if Max is less than Ptr, then this is a

   --  special case of an all-blank string, and Ptr is unchanged, and hence

   --  is greater than Max as required in this case.

   function Value_Decimal (Str : String; Scale : Integer) return Integer;

   --  Used in computing X'Value (Str) where X is a decimal types whose size

   --  does not exceed Standard.Integer'Size. Str is the string argument of

   --  the attribute. Constraint_Error is raised if the string is malformed

   --  or if the value is out of range, otherwise the value returned is the

   --  value Integer'Integer_Value (decimal-literal-value), using the given

   --  Scale to determine this value.

end System.Val_Dec;