gcc/gcc/ada/s-valuns.ads

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--                                                                          --
--                         GNAT COMPILER COMPONENTS                         --
--                                                                          --
--                       S Y S T E M . V A L _ U N S                        --
--                                                                          --
--                                 S p e c                                  --
--                                                                          --
--          Copyright (C) 1992-2005, Free Software Foundation, Inc.         --
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--                                                                          --
------------------------------------------------------------------------------

--  This package contains routines for scanning modular Unsigned
--  values for use in Text_IO.Modular, and the Value attribute.

with System.Unsigned_Types;

package System.Val_Uns is
   pragma Pure;

   function Scan_Unsigned
     (Str : String;
      Ptr : access Integer;
      Max : Integer) return System.Unsigned_Types.Unsigned;
   --  This function scans the string starting at Str (Ptr.all) for a valid
   --  integer 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 integer is found after scanning past any initial spaces, then
   --  Ptr.all is updated past the last character of the integer (but trailing
   --  spaces are not scanned out).
   --
   --  If no valid integer 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 that if a minus sign is present, and
   --  the integer value is non-zero, then constraint error will be 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_Unsigned
     (Str : String) return System.Unsigned_Types.Unsigned;
   --  Used in computing X'Value (Str) where X is a modular integer type whose
   --  modulus does not exceed the range of System.Unsigned_Types.Unsigned. 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.

end System.Val_Uns;