------------------------------------------------------------------------------
--                                                                          --
--                         GNAT RUN-TIME COMPONENTS                         --
--                                                                          --
--                      G N A T . E X C E P T I O N S                       --
--                                                                          --
--                                 S p e c                                  --
--                                                                          --
--                            $Revision: 1.1 $
--                                                                          --
--           Copyright (C) 2000-2001 Ada Core Technologies, Inc.            --
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-- GNAT is free software;  you can  redistribute it  and/or modify it under --
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-- As a special exception,  if other files  instantiate  generics from this --
-- unit, or you link  this unit with other files  to produce an executable, --
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-- covered  by the  GNU  General  Public  License.  This exception does not --
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-- covered by the  GNU Public License.                                      --
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-- GNAT was originally developed  by the GNAT team at  New York University. --
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--                                                                          --
------------------------------------------------------------------------------

--  This package provides an interface for raising predefined exceptions
--  with an exception message. It can be used from Pure units. This unit
--  is for internal use only, it is not generally available to applications.

package GNAT.Exceptions is
pragma Pure (Exceptions);

   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;
