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More safety, also after terms and nonterminals.

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This commit is contained in:
ceriel
1985-10-03 12:38:55 +00:00
parent 5be4b432dc
commit c1d4bb2597
4 changed files with 58 additions and 51 deletions
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61
util/LLgen/src/compute.c
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@@ -670,28 +670,28 @@ co_safes() {
/*
* Don't know anything yet
*/
setntsafe(&(p->n_flags), NOSAFETY);
setntsafe(p, NOSAFETY);
setntout(p, NOSAFETY);
}
for (st = start; st; st = st->ff_next) {
/*
* But start symbols are called with lookahead done
*/
p = st->ff_nont;
setntsafe(&(p->n_flags),SCANDONE);
setntsafe(p,SCANDONE);
}
change = 1;
while (change) {
change = 0;
for (p = nonterms; p < maxnt; p++) {
i = getntsafe(p->n_flags);
i = getntsafe(p);
if (i == NOSAFETY) {
change = 1;
continue;
}
if (do_safes(p->n_rule, i) == 2 &&
!(p->n_flags & NNOSCAN)) {
p->n_flags |= NNOSCAN;
i = do_safes(p->n_rule, i);
if (getntout(p) != i) {
change = 1;
setntout(p, i);
}
}
}
@@ -705,8 +705,6 @@ do_safes(p,safe) register p_gram p; {
*/
register retval;
if (safe == NOSCANDONE) retval = 2;
else retval = 1;
for (;;) {
switch (g_gettype(p)) {
case ACTION:
@@ -724,10 +722,10 @@ do_safes(p,safe) register p_gram p; {
rep = r_getkind(&(q->t_reps));
retval = do_safes(q->t_rule,
t_safety(rep,i,q->t_flags&PERSISTENT,safe));
if (retval == 2 && (!(q->t_flags & TNOSCAN))) {
q->t_flags |= TNOSCAN;
if (retval != gettout(q)) {
settout(q, retval);
}
safe = t_after(rep, i, q->t_flags & TNOSCAN);
safe = t_after(rep, i, gettout(q));
break; }
case ALTERNATION : {
register p_link l;
@@ -736,51 +734,53 @@ do_safes(p,safe) register p_gram p; {
f = 1;
while (g_gettype(p) == ALTERNATION) {
l = (p_link) pentry[g_getcont(p)];
if (safe && (l->l_flag & DEF)) {
if (safe > SAFE && (l->l_flag & DEF)) {
i = do_safes(l->l_rule,SAFESCANDONE);
}
else i = do_safes(l->l_rule,SAFE);
if (f) retval = i;
else retval &= i;
else if (i != retval) {
if (i == NOSCANDONE ||
retval == NOSCANDONE) {
retval = SCANDONE;
}
else if (i > retval) retval = i;
}
p++;
f = 0;
}
return retval; }
case NONTERM : {
register p_nont n;
int nsafe, osafe;;
int nsafe, osafe;
n = &nonterms[g_getnont(p)];
nsafe = getntsafe(n->n_flags);
nsafe = getntsafe(n);
osafe = safe;
if (!(n->n_flags & NNOSCAN)) {
safe = SCANDONE;
}
else safe = NOSCANDONE;
safe = getntout(n);
if (safe == NOSAFETY) safe = SCANDONE;
if (osafe == nsafe) break;
if (nsafe == NOSAFETY) {
change = 1;
setntsafe(&(n->n_flags), osafe);
setntsafe(n, osafe);
break;
}
if (osafe == NOSCANDONE || nsafe == NOSCANDONE) {
if (nsafe != SCANDONE) {
change = 1;
setntsafe(&(n->n_flags), SCANDONE);
setntsafe(n, SCANDONE);
}
break;
}
if (osafe > nsafe) {
setntsafe(&(n->n_flags), osafe);
setntsafe(n, osafe);
change = 1;
}
break; }
case EORULE :
return retval;
return safe;
}
p++;
if (safe == NOSCANDONE) retval = 2;
else retval = 1;
}
}
@@ -814,10 +814,13 @@ t_safety(rep, count, persistent, safety) {
/* NOTREACHED */
}
t_after(rep, count, noscan) {
t_after(rep, count, outsafety) {
if (count == 0 && (rep == STAR || rep == PLUS)) {
return SAFESCANDONE;
}
if (rep == FIXED && noscan) return NOSCANDONE;
return SCANDONE;
if (rep != FIXED) {
if (outsafety <= SAFESCANDONE) return SAFESCANDONE;
return SCANDONE;
}
return outsafety;
}