libchill/exh.c

   1 /* Implement runtime actions for CHILL.
   2    Copyright (C) 1992,1993 Free Software Foundation, Inc.
   3    Author: Wilfried Moser
   4
   5 This file is part of GNU CC.
   6
   7 GNU CC is free software; you can redistribute it and/or modify
   8 it under the terms of the GNU General Public License as published by
   9 the Free Software Foundation; either version 2, or (at your option)
  10 any later version.
  11
  12 GNU CC is distributed in the hope that it will be useful,
  13 but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 GNU General Public License for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GNU CC; see the file COPYING.  If not, write to
  19 the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
  20
  21 #define __CHILL_LIB__
  22
  23 #include <stdio.h>
  24 #include <setjmp.h>
  25 #include "rtltypes.h"
  26
  27 extern void cause_exception (char *exname, char *file, int lineno, int user_arg);
  28 extern void unhandled_exception (char *exname, char *file, int lineno, int user_arg);
  29
  30 /* An action with a handler:
  31         BODY ON (e1, e2): H12; (e3): H3; ELSE HE; END;
  32    is translated into:
  33
  34     struct __ch_handler __tmp;
  35     static struct __ch_handler_excepts _H[4] =
  36       {
  37         { <<e1>>, 1 },
  38         { <<e2>>, 1 },
  39         { <<e3>>, 2 },
  40         { __ch_else_except, 3 },
  41       };
  42     __ch_link_handler(&__tmp);
  43     __tmp.handlers = _H;
  44     switch (setmp(&__tmp.jbuf))
  45       {
  46       case 0:  BODY; __ch_unlink_handler(&__tmp); break;
  47       case 1:  H12; break;
  48       case 2:  H3; break;
  49       case 3:  HE; break;
  50       }
  51 */
  52
  53 /* this part contains all neccessary functions to handle exceptions in CHILL */
  54
  55 /* These two trivial function aren't inlines, to allow for
  56    more flexibility (e.g. a per-thread exception stack). */
  57
  58 extern void __setexceptionStack (TExceptionHandlerStack *new);
  59 extern TExceptionHandlerStack * __getexceptionStack (void);
  60
  61 void
  62 __ch_link_handler (handler)
  63      struct __ch_handler *handler;
  64 {
  65   handler->prev = __getexceptionStack ();
  66   __setexceptionStack (handler);
  67 }
  68
  69  void
  70 __ch_unlink_handler (handler)
  71      struct __ch_handler *handler;
  72 {
  73   __setexceptionStack (handler->prev);
  74 }
  75
  76 /*
  77  * function __cause_exception
  78  *
  79  * parameters:
  80  *  exnum               name string of exception to raise
  81  *  file                filename of CAUSE statement
  82  *  lineno              linenumber of CAUSE statement
  83  *  user_arg            user specified argument
  84  *
  85  * returns:
  86  *  never               leave function with longjmp or abort
  87  *
  88  * abstract:
  89  *  search exceptionstack for last handler of caused exception,
  90  *  call userdefined function to signal exception,
  91  *  jump to handler with longjmp or call unhandled_exception
  92  *
  93  */
  94
  95 void
  96 __cause_exception  (ex, file, lineno, user_arg)
  97      char *ex;
  98      char *file;
  99      int  lineno;
 100      int user_arg;
 101 {
 102   register struct __ch_handler *handler = __getexceptionStack();
 103
 104   /* call user defined cause function */
 105   cause_exception (ex, file, lineno, user_arg);
 106
 107   for ( ; handler != NULL; handler = handler->prev)
 108     {
 109       register struct __ch_handled_excepts *list = handler->handlers;
 110       for ( ; list->code != 0; list++ )
 111         {
 112           if (list->ex == __ch_else_except || EX_EQ(list->ex, ex)) /* found */
 113             {
 114               __setexceptionStack (handler->prev);
 115               longjmp(handler->jbuf, list->code);
 116             }
 117         }
 118     }
 119
 120   /* no handler found -- call unhandled_exception */
 121   unhandled_exception (ex, file, lineno, user_arg);
 122   abort ();
 123 }
 124
 125 /*
 126  * function __cause_ex1
 127  *
 128  * parameters:
 129  *  exnum               name string of exception to raise
 130  *  file                filename of CAUSE statement
 131  *  lineno              linenumber of CAUSE statement
 132  *
 133  * returns:
 134  *  never               leave function with longjmp or abort
 135  *
 136  * abstract:
 137  *  This is the function the compiler generated code calls.
 138  *  Search exceptionstack for last handler of caused exception,
 139  *  call userdefined function to signal exception,
 140  *  jump to handler with longjmp or call unhandled_exception
 141  *
 142  */
 143
 144 void
 145 __cause_ex1  (ex, file, lineno)
 146      char *ex;
 147      char *file;
 148      int  lineno;
 149 {
 150   __cause_exception (ex, file, lineno, 0);
 151 }