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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) 1992,1993,1994,1995,1996 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 2, 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. See the GNU General Public License --
-- for more details. You should have received a copy of the GNU General --
-- Public License distributed with GNAT; see file COPYING. If not, write --
-- to the Free Software Foundation, 51 Franklin Street, Fifth Floor, --
-- Boston, MA 02110-1301, USA. --
-- --
-- As a special exception, if other files instantiate generics from this --
-- unit, or you link this unit with other files to produce an executable, --
-- this unit does not by itself cause the resulting executable to be --
-- covered by the GNU General Public License. This exception does not --
-- however invalidate any other reasons why the executable file might be --
-- covered by the GNU Public License. --
-- --
-- GNAT was originally developed by the GNAT team at New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc. --
-- --
------------------------------------------------------------------------------
-- 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 (Val_Uns);
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;
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