ls9-error.nw

Error reporting and handling

<<ls9 globals>>=
full	Trace[NTRACE];
full	Tp = 0;

size_t	Plimit = 0;

full	Line = 1;
full	Files = NIL;

full	Symbols;

jmp_buf	Restart;
jmp_buf	Errtag;
full	Handler = NIL;

full	Glob;
full	S_errtag, S_errval;
@

<<ls9 impl>>=
void clrtrace(void) {
	int	i;

	for (i=0; i<NTRACE; i++) Trace[i] = NIL;
}

int gottrace(void) {
	int	i;

	for (i=0; i<NTRACE; i++)
		if (Trace[i] != NIL) return 1;
	return 0;
}

void report(char *s, full x) {
	full	i, j, o;

	o = set_outport(2);
	prints("*** error: ");
	prints(s);
	if (x != UNDEF) {
		prints(": ");
		Plimit = 100;
		prin(x);
		Plimit = 0;
	}
	nl();
	if (Files != NIL) {
		prints("*** file: ");
		printb(string(car(Files)));
		prints(", line: ");
		prints(ntoa((ifull)Line, 10));
		nl();
	}
	if (gottrace()) {
		prints("*** trace:");
		i = Tp;
		for (j=0; j<NTRACE; j++) {
			if (i >= NTRACE) i = 0;
			if (Trace[i] != NIL) {
				prints(" ");
				printb(symname(vector(Symbols)[Trace[i]]));
			}
			i++;
		}
		nl();
	}
	set_outport(o);
}

void error(char *s, full x) {
	full	n;

	n = assq(S_errtag, Glob);
	Handler = (NIL == n)? NIL: cadr(n);
	if (Handler != NIL) {
		n = assq(S_errval, Glob);
		if (n != NIL && cadr(n) == Handler)
			bindset(S_errval, mkstr(s, strlen(s)));
		longjmp(Errtag, 1);
	}
	report(s, x);
	longjmp(Restart, 1);
}

void expect(char *who, char *what, full got) {
	char	b[100];

	sprintf(b, "%s: expected %s", who, what);
	error(b, got);
}

void fatal(char *s) {
	fprintf(stderr, "*** fatal error: ");
	fprintf(stderr, "%s\n", s);
	exit(EXIT_FAILURE);
}
@