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--                                                                          --

--                         GNAT LIBRARY COMPONENTS                          --

--                                                                          --

--               G N A T . C U R R E N T _ E X C E P T I O N                --

--                                                                          --

--                                 S p e c                                  --

--                                                                          --

--                      Copyright (C) 1996-2008, AdaCore                    --

--                                                                          --

-- 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 provides routines for obtaining the current exception

--  information in Ada 83 style. In Ada 83, there was no official method

--  for obtaining exception information, but a number of vendors supplied

--  routines for this purpose, and this package closely approximates the

--  interfaces supplied by DEC Ada 83 and VADS Ada.

--  The routines in this package are associated with a particular exception

--  handler, and can only be called from within an exception handler. See

--  also the package GNAT.Most_Recent_Exception, which provides access to

--  the most recently raised exception, and is not limited to static calls

--  from an exception handler.

package GNAT.Current_Exception is

   pragma Pure;

   -----------------

   -- Subprograms --

   -----------------

   --  Note: the lower bound of returned String values is always one

   function Exception_Information return String;

   --  Returns the result of calling Ada.Exceptions.Exception_Information

   --  with an argument that is the Exception_Occurrence corresponding to

   --  the current exception. Returns the null string if called from outside

   --  an exception handler.

   function Exception_Message return String;

   --  Returns the result of calling Ada.Exceptions.Exception_Message with

   --  an argument that is the Exception_Occurrence corresponding to the

   --  current exception. Returns the null string if called from outside an

   --  exception handler.

   function Exception_Name return String;

   --  Returns the result of calling Ada.Exceptions.Exception_Name with

   --  an argument that is the Exception_Occurrence corresponding to the

   --  current exception. Returns the null string if called from outside

   --  an exception handler.

   --  Note: all these functions return useful information only if

   --  called statically from within an exception handler, and they

   --  return information about the exception corresponding to the

   --  handler in which they appear. This is NOT the same as the most

   --  recently raised exception. Consider the example:

   --     exception

   --        when Constraint_Error =>

   --          begin

   --             ...

   --          exception

   --             when Tasking_Error => ...

   --          end;

   --

   --          -- Exception_xxx at this point returns the information about

   --          -- the constraint error, not about any exception raised within

   --          -- the nested block since it is the static nesting that counts.

   -----------------------------------

   -- Use of Library Level Renaming --

   -----------------------------------

   --  For greater compatibility with existing legacy software, library

   --  level renaming may be used to create a function with a name matching

   --  one that is in use. For example, some versions of VADS Ada provided

   --  a function called Current_Exception whose semantics was identical to

   --  that of GNAT. The following library level renaming declaration:

   --    with GNAT.Current_Exception;

   --    function Current_Exception

   --      renames GNAT.Current_Exception.Exception_Name;

   --  placed in a file called current_exception.ads and compiled into the

   --  application compilation environment, will make the function available

   --  in a manner exactly compatible with that in VADS Ada 83.

private

   pragma Import (Intrinsic, Exception_Information);

   pragma Import (intrinsic, Exception_Message);

   pragma Import (Intrinsic, Exception_Name);

end GNAT.Current_Exception;