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/*
* Copyright (C) 2008 Free Software Foundation, Inc.
* This file is part of GNU Modula-2.
*
* GNU Modula-2 is free software; you can redistribute it and/or modify it under
* the terms of the GNU General Public License as published by the Free
* Software Foundation; either version 2, or (at your option) any later
* version.
*
* GNU Modula-2 is distributed in the hope that it will be useful, but WITHOUT ANY
* WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* for more details.
*
* You should have received a copy of the GNU General Public License along
* with gm2; see the file COPYING. If not, write to the Free Software
* Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
#include <setjmp.h>
#include <malloc.h>
#include <stdio.h>
typedef enum jmpstatus {
jmp_normal,
jmp_retry,
jmp_exception,
} jmp_status;
struct setjmp_stack {
jmp_buf env;
struct setjmp_stack *next;
} *head = NULL;
void pushsetjmp (void)
{
struct setjmp_stack *p = (struct setjmp_stack *) malloc (sizeof (struct setjmp_stack));
p->next = head;
head = p;
}
void exception (void)
{
printf("invoking exception handler\n");
longjmp (head->env, jmp_exception);
}
void retry (void)
{
printf("retry\n");
longjmp (head->env, jmp_retry);
}
void popsetjmp (void)
{
struct setjmp_stack *p = head;
head = head->next;
free (p);
}
static int *ip = NULL;
void fly (void)
{
printf("fly main body\n");
if (ip == NULL) {
printf("ip == NULL\n");
exception();
}
if ((*ip) == 0) {
printf("*ip == 0\n");
exception();
}
if ((4 / (*ip)) == 4)
printf("yes it worked\n");
else
printf("no it failed\n");
}
/*
* a GNU C version of the Modula-2 example given in the ISO standard.
* This is written to prove that the underlying runtime system
* will work with the C interpretation. Thus gm2 will produce
* trees which follow the "template" setjmp/longjmp schema below
* when compiling EXCEPT/TRY statements.
*/
void tryFlying (void)
{
void tryFlying_m2_exception () {
printf("inside tryFlying exception routine\n");
if ((ip != NULL) && ((*ip) == 0)) {
(*ip) = 1;
retry();
}
}
int t;
pushsetjmp ();
do {
t = setjmp (head->env);
} while (t == jmp_retry);
if (t == jmp_exception) {
/* exception called */
tryFlying_m2_exception ();
/* exception has not been handled, invoke previous handler */
printf("exception not handled here\n");
popsetjmp();
exception();
}
printf("tryFlying main body\n");
fly();
popsetjmp();
}
void keepFlying (void)
{
void keepFlying_m2_exception () {
printf("inside keepFlying exception routine\n");
if (ip == NULL) {
ip = (int *)malloc (sizeof (int));
*ip = 0;
retry();
}
}
int t;
pushsetjmp ();
do {
t = setjmp (head->env);
} while (t == jmp_retry);
if (t == jmp_exception) {
/* exception called */
keepFlying_m2_exception ();
/* exception has not been handled, invoke previous handler */
popsetjmp();
exception();
}
printf("keepFlying main body\n");
tryFlying();
popsetjmp();
}
main ()
{
keepFlying();
printf("all done\n");
}
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