File : s-valrea.ads


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--                                                                          --
--                         GNAT COMPILER COMPONENTS                         --
--                                                                          --
--                      S Y S T E M . V A L _ R E A L                       --
--                                                                          --
--                                 S p e c                                  --
--                                                                          --
--                            $Revision: 1.8 $                              --
--                                                                          --
--   Copyright (C) 1992,1993,1994,1995,1996 Free Software Foundation, Inc.  --
--                                                                          --
-- GNAT is free software;  you can  redistribute it  and/or modify it under --
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-- As a special exception,  if other files  instantiate  generics from this --
-- unit, or you link  this unit with other files  to produce an executable, --
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-- covered by the  GNU Public License.                                      --
--                                                                          --
-- GNAT was originally developed  by the GNAT team at  New York University. --
-- It is now maintained by Ada Core Technologies Inc (http://www.gnat.com). --
--                                                                          --
------------------------------------------------------------------------------

package System.Val_Real is
pragma Pure (Val_Real);

   function Scan_Real
     (Str  : String;
      Ptr  : access Integer;
      Max  : Integer)
      return Long_Long_Float;
   --  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 is found after scanning past any initial spaces, then
   --  Ptr.all is updated past the last character of the real (but trailing
   --  spaces are not scanned out).
   --
   --  If no valid real is found, then Ptr.all points either to an initial
   --  non-blank character, or to Max + 1 if the field is all spaces and the
   --  exception Constraint_Error is raised.
   --
   --  If a syntactically valid real 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 real literal,
   --  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_Real (Str : String) return Long_Long_Float;
   --  Used in computing X'Value (Str) where X is a floating-point type or an
   --  ordinary fixed-point type. Str is the string argument of the attribute.
   --  Constraint_Error is raised if the string is malformed, or if the value
   --  out of range of Long_Long_Float.

end System.Val_Real;