------------------------------------------------------------------------------
--                                                                          --
--                         GNAT RUN-TIME COMPONENTS                         --
--                                                                          --
--                S Y S T E M . E X C E P T I O N _ T R A C E S             --
--                                                                          --
--                                 S p e c                                  --
--                                                                          --
--                     Copyright (C) 2000-2020, 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 3,  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.                                     --
--                                                                          --
-- As a special exception under Section 7 of GPL version 3, you are granted --
-- additional permissions described in the GCC Runtime Library Exception,   --
-- version 3.1, as published by the Free Software Foundation.               --
--                                                                          --
-- You should have received a copy of the GNU General Public License and    --
-- a copy of the GCC Runtime Library Exception along with this program;     --
-- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
-- <http://www.gnu.org/licenses/>.                                          --
--                                                                          --
-- GNAT was originally developed  by the GNAT team at  New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc.      --
--                                                                          --
------------------------------------------------------------------------------

--  This package provides an interface allowing to control *automatic* output
--  to standard error upon exception occurrences (as opposed to explicit
--  generation of traceback information using System.Traceback).

--  This output includes the basic information associated with the exception
--  (name, message) as well as a backtrace of the call chain at the point
--  where the exception occurred. This backtrace is only output if the call
--  chain information is available, depending if the binder switch dedicated
--  to that purpose has been used or not.

--  The default backtrace is in the form of absolute code locations which may
--  be converted to corresponding source locations using the addr2line utility
--  or from within GDB. Please refer to System.Traceback for information about
--  what is necessary to be able to exploit this possibility.

--  The backtrace output can also be customized by way of a "decorator" which
--  may return any string output in association with a provided call chain.
--  The decorator replaces the default backtrace mentioned above.

--  On systems that use DWARF debugging output, then if the "-g" compiler
--  switch and the "-Es" binder switch are used, the decorator is automatically
--  set to Symbolic_Traceback.

with System.Traceback_Entries;

package System.Exception_Traces is

   --  The following defines the exact situations in which raises will
   --  cause automatic output of trace information.

   type Trace_Kind is
     (Every_Raise,
      --  Denotes the initial raise event for any exception occurrence, either
      --  explicit or due to a specific language rule, within the context of a
      --  task or not.

      Unhandled_Raise,
      --  Denotes the raise events corresponding to exceptions for which there
      --  is no user defined handler. This includes unhandled exceptions in
      --  task bodies.

      Unhandled_Raise_In_Main
      --  Same as Unhandled_Raise, except exceptions in task bodies are not
      --  included.
     );

   --  The following procedures can be used to activate and deactivate
   --  traces identified by the above trace kind values.

   procedure Trace_On (Kind : Trace_Kind);
   --  Activate the traces denoted by Kind

   procedure Trace_Off;
   --  Stop the tracing requested by the last call to Trace_On.
   --  Has no effect if no such call has ever occurred.

   --  The following provide the backtrace decorating facilities

   type Traceback_Decorator is access
     function (Traceback : Traceback_Entries.Tracebacks_Array) return String;
   --  A backtrace decorator is a function which returns the string to be
   --  output for a call chain provided by way of a tracebacks array.

   procedure Set_Trace_Decorator (Decorator : Traceback_Decorator);
   --  Set the decorator to be used for future automatic outputs. Restore the
   --  default behavior if the provided access value is null.
   --
   --  Note: System.Traceback.Symbolic.Symbolic_Traceback may be used as the
   --  Decorator, to get a symbolic traceback. This will cause a significant
   --  cpu and memory overhead on some platforms.
   --
   --  Note: The Decorator is called when constructing the
   --  Exception_Information; that needs to be taken into account
   --  if the Decorator has any side effects.

end System.Exception_Traces;
