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--                                                                          --

--                         GNAT RUN-TIME COMPONENTS                         --

--                                                                          --

--                      G N A T . E X C E P T I O N S                       --

--                                                                          --

--                                 S p e c                                  --

--                                                                          --

--                     Copyright (C) 2000-2008, 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.      --

--                                                                          --

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--  This package provides an interface for raising predefined exceptions

--  with an exception message. It can be used from Pure units.

--  There is no prohibition in Ada that prevents exceptions being raised

--  from within pure units. The raise statement is perfectly acceptable.

--  However, it is not normally possible to raise an exception with a

--  message because the routine Ada.Exceptions.Raise_Exception is not in

--  a Pure unit. This is an annoying and unnecessary restriction and this

--  package allows for raising the standard predefined exceptions at least.

package GNAT.Exceptions is

   pragma Pure;

   type Exception_Type is limited null record;

   --  Type used to specify which exception to raise

   --  Really Exception_Type is Exception_Id, but Exception_Id can't be

   --  used directly since it is declared in the non-pure unit Ada.Exceptions,

   --  Exception_Id is in fact simply a pointer to the type Exception_Data

   --  declared in System.Standard_Library (which is also non-pure). So what

   --  we do is to define it here as a by reference type (any by reference

   --  type would do), and then Import the definitions from Standard_Library.

   --  Since this is a by reference type, these will be passed by reference,

   --  which has the same effect as passing a pointer.

   --  This type is not private because keeping it by reference would require

   --  defining it in a way (e.g a tagged type) that would drag other run time

   --  files, which is unwanted in the case of e.g ravenscar where we want to

   --  minimize the number of run time files needed by default.

   CE : constant Exception_Type;  -- Constraint_Error

   PE : constant Exception_Type;  -- Program_Error

   SE : constant Exception_Type;  -- Storage_Error

   TE : constant Exception_Type;  -- Tasking_Error

   --  One of these constants is used in the call to specify the exception

   procedure Raise_Exception (E : Exception_Type; Message : String);

   pragma Import (Ada, Raise_Exception, "__gnat_raise_exception");

   pragma No_Return (Raise_Exception);

   --  Raise specified exception with specified message

private

   pragma Import (C, CE, "constraint_error");

   pragma Import (C, PE, "program_error");

   pragma Import (C, SE, "storage_error");

   pragma Import (C, TE, "tasking_error");

   --  References to the exception structures in the standard library

end GNAT.Exceptions;