gcc/ada/g-exctra.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT RUN-TIME COMPONENTS                         --
   4 --                                                                          --
   5 --                  G N A T . E X C E P T I O N _ T R A C E S               --
   6 --                                                                          --
   7 --                                 B o d y                                  --
   8 --                                                                          --
   9 --            Copyright (C) 2000-2002 Ada Core Technologies, Inc.           --
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  25 -- covered  by the  GNU  General  Public  License.  This exception does not --
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  27 -- covered by the  GNU Public License.                                      --
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  30 --                                                                          --
  31 ------------------------------------------------------------------------------
  32
  33 with System.Standard_Library; use System.Standard_Library;
  34 with System.Soft_Links;       use System.Soft_Links;
  35
  36 package body GNAT.Exception_Traces is
  37
  38    --  Calling the decorator directly from where it is needed would require
  39    --  introducing nasty dependencies upon the spec of this package (typically
  40    --  in a-except.adb). We also have to deal with the fact that the traceback
  41    --  array within an exception occurrence and the one the decorator shall
  42    --  accept are of different types. These are two reasons for which a wrapper
  43    --  with a System.Address argument is indeed used to call the decorator
  44    --  provided by the user of this package. This wrapper is called via a
  45    --  soft-link, which either is null when no decorator is in place or "points
  46    --  to" the following function otherwise.
  47
  48    function Decorator_Wrapper
  49      (Traceback : System.Address;
  50       Len       : Natural)
  51       return      String;
  52    --  The wrapper to be called when a decorator is in place for exception
  53    --  backtraces.
  54    --
  55    --  Traceback is the address of the call chain array as stored in the
  56    --  exception occurrence and Len is the number of significant addresses
  57    --  contained in this array.
  58
  59    Current_Decorator : Traceback_Decorator := null;
  60    --  The decorator to be called by the wrapper when it is not null, as set
  61    --  by Set_Trace_Decorator. When this access is null, the wrapper is null
  62    --  also and shall then not be called.
  63
  64    -----------------------
  65    -- Decorator_Wrapper --
  66    -----------------------
  67
  68    function Decorator_Wrapper
  69      (Traceback : System.Address;
  70       Len       : Natural)
  71       return      String
  72    is
  73       Decorator_Traceback : Tracebacks_Array (1 .. Len);
  74       for Decorator_Traceback'Address use Traceback;
  75
  76       --  Handle the "transition" from the array stored in the exception
  77       --  occurrence to the array expected by the decorator.
  78
  79       pragma Import (Ada, Decorator_Traceback);
  80
  81    begin
  82       return Current_Decorator.all (Decorator_Traceback);
  83    end Decorator_Wrapper;
  84
  85    -------------------------
  86    -- Set_Trace_Decorator --
  87    -------------------------
  88
  89    procedure Set_Trace_Decorator (Decorator : Traceback_Decorator) is
  90    begin
  91       Current_Decorator := Decorator;
  92
  93       if Current_Decorator /= null then
  94          Traceback_Decorator_Wrapper := Decorator_Wrapper'Access;
  95       else
  96          Traceback_Decorator_Wrapper := null;
  97       end if;
  98    end Set_Trace_Decorator;
  99
 100    --  Trace_On/Trace_Off control the kind of automatic output to occur
 101    --  by way of the global Exception_Trace variable.
 102
 103    ---------------
 104    -- Trace_Off --
 105    ---------------
 106
 107    procedure Trace_Off is
 108    begin
 109       Exception_Trace := RM_Convention;
 110    end Trace_Off;
 111
 112    --------------
 113    -- Trace_On --
 114    --------------
 115
 116    procedure Trace_On (Kind : Trace_Kind) is
 117    begin
 118       case Kind is
 119          when Every_Raise =>
 120             Exception_Trace := Every_Raise;
 121          when Unhandled_Raise =>
 122             Exception_Trace := Unhandled_Raise;
 123       end case;
 124    end Trace_On;
 125
 126 end GNAT.Exception_Traces;