gcc/ada/g-curexc.ads

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT LIBRARY COMPONENTS                          --
   4 --                                                                          --
   5 --               G N A T . C U R R E N T _ E X C E P T I O N                --
   6 --                                                                          --
   7 --                                 S p e c                                  --
   8 --                                                                          --
   9 --                      Copyright (C) 1996-2010, AdaCore                    --
  10 --                                                                          --
  11 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
  12 -- terms of the  GNU General Public License as published  by the Free Soft- --
  13 -- ware  Foundation;  either version 3,  or (at your option) any later ver- --
  14 -- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
  15 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  16 -- or FITNESS FOR A PARTICULAR PURPOSE.                                     --
  17 --                                                                          --
  18 -- As a special exception under Section 7 of GPL version 3, you are granted --
  19 -- additional permissions described in the GCC Runtime Library Exception,   --
  20 -- version 3.1, as published by the Free Software Foundation.               --
  21 --                                                                          --
  22 -- You should have received a copy of the GNU General Public License and    --
  23 -- a copy of the GCC Runtime Library Exception along with this program;     --
  24 -- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
  25 -- <http://www.gnu.org/licenses/>.                                          --
  26 --                                                                          --
  27 -- GNAT was originally developed  by the GNAT team at  New York University. --
  28 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  29 --                                                                          --
  30 ------------------------------------------------------------------------------
  31
  32 --  This package provides routines for obtaining the current exception
  33 --  information in Ada 83 style. In Ada 83, there was no official method
  34 --  for obtaining exception information, but a number of vendors supplied
  35 --  routines for this purpose, and this package closely approximates the
  36 --  interfaces supplied by DEC Ada 83 and VADS Ada.
  37
  38 --  The routines in this package are associated with a particular exception
  39 --  handler, and can only be called from within an exception handler. See
  40 --  also the package GNAT.Most_Recent_Exception, which provides access to
  41 --  the most recently raised exception, and is not limited to static calls
  42 --  from an exception handler.
  43
  44 package GNAT.Current_Exception is
  45    pragma Pure;
  46
  47    -----------------
  48    -- Subprograms --
  49    -----------------
  50
  51    --  Note: the lower bound of returned String values is always one
  52
  53    function Exception_Information return String;
  54    --  Returns the result of calling Ada.Exceptions.Exception_Information
  55    --  with an argument that is the Exception_Occurrence corresponding to
  56    --  the current exception. Returns the null string if called from outside
  57    --  an exception handler.
  58
  59    function Exception_Message return String;
  60    --  Returns the result of calling Ada.Exceptions.Exception_Message with
  61    --  an argument that is the Exception_Occurrence corresponding to the
  62    --  current exception. Returns the null string if called from outside an
  63    --  exception handler.
  64
  65    function Exception_Name return String;
  66    --  Returns the result of calling Ada.Exceptions.Exception_Name with
  67    --  an argument that is the Exception_Occurrence corresponding to the
  68    --  current exception. Returns the null string if called from outside
  69    --  an exception handler.
  70
  71    --  Note: all these functions return useful information only if
  72    --  called statically from within an exception handler, and they
  73    --  return information about the exception corresponding to the
  74    --  handler in which they appear. This is NOT the same as the most
  75    --  recently raised exception. Consider the example:
  76
  77    --     exception
  78    --        when Constraint_Error =>
  79    --          begin
  80    --             ...
  81    --          exception
  82    --             when Tasking_Error => ...
  83    --          end;
  84    --
  85    --          -- Exception_xxx at this point returns the information about
  86    --          -- the constraint error, not about any exception raised within
  87    --          -- the nested block since it is the static nesting that counts.
  88
  89    -----------------------------------
  90    -- Use of Library Level Renaming --
  91    -----------------------------------
  92
  93    --  For greater compatibility with existing legacy software, library
  94    --  level renaming may be used to create a function with a name matching
  95    --  one that is in use. For example, some versions of VADS Ada provided
  96    --  a function called Current_Exception whose semantics was identical to
  97    --  that of GNAT. The following library level renaming declaration:
  98
  99    --    with GNAT.Current_Exception;
 100    --    function Current_Exception
 101    --      renames GNAT.Current_Exception.Exception_Name;
 102
 103    --  placed in a file called current_exception.ads and compiled into the
 104    --  application compilation environment, will make the function available
 105    --  in a manner exactly compatible with that in VADS Ada 83.
 106
 107 private
 108    pragma Import (Intrinsic, Exception_Information);
 109    pragma Import (intrinsic, Exception_Message);
 110    pragma Import (Intrinsic, Exception_Name);
 111
 112 end GNAT.Current_Exception;