s-valdec.ads   [plain text]

--                                                                          --
--                         GNAT COMPILER COMPONENTS                         --
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--                       S Y S T E M . V A L _ D E C                        --
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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 (Val_Dec);

   function Scan_Decimal
     (Str   : String;
      Ptr   : 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;