cpython/Parser/firstsets.c

114 lines
2.3 KiB
C
Raw Normal View History

1991-02-19 08:39:46 -04:00
1990-10-14 09:07:46 -03:00
/* Computation of FIRST stets */
1990-12-20 11:06:42 -04:00
#include "pgenheaders.h"
1990-10-14 09:07:46 -03:00
#include "grammar.h"
#include "token.h"
1997-04-29 18:03:06 -03:00
extern int Py_DebugFlag;
1990-10-14 09:07:46 -03:00
1990-12-20 11:06:42 -04:00
/* Forward */
static void calcfirstset(grammar *, dfa *);
1990-12-20 11:06:42 -04:00
void
addfirstsets(grammar *g)
1990-12-20 11:06:42 -04:00
{
int i;
dfa *d;
2001-09-11 13:43:16 -03:00
if (Py_DebugFlag)
printf("Adding FIRST sets ...\n");
1990-12-20 11:06:42 -04:00
for (i = 0; i < g->g_ndfas; i++) {
d = &g->g_dfa[i];
if (d->d_first == NULL)
calcfirstset(g, d);
}
}
1990-10-14 09:07:46 -03:00
static void
calcfirstset(grammar *g, dfa *d)
1990-10-14 09:07:46 -03:00
{
int i, j;
state *s;
arc *a;
int nsyms;
int *sym;
int nbits;
static bitset dummy;
bitset result;
int type;
dfa *d1;
label *l0;
1997-04-29 18:03:06 -03:00
if (Py_DebugFlag)
1990-10-14 09:07:46 -03:00
printf("Calculate FIRST set for '%s'\n", d->d_name);
if (dummy == NULL)
dummy = newbitset(1);
if (d->d_first == dummy) {
fprintf(stderr, "Left-recursion for '%s'\n", d->d_name);
return;
}
if (d->d_first != NULL) {
fprintf(stderr, "Re-calculating FIRST set for '%s' ???\n",
d->d_name);
}
d->d_first = dummy;
l0 = g->g_ll.ll_label;
nbits = g->g_ll.ll_nlabels;
result = newbitset(nbits);
sym = (int *)PyObject_MALLOC(sizeof(int));
1990-10-14 09:07:46 -03:00
if (sym == NULL)
1997-04-29 18:03:06 -03:00
Py_FatalError("no mem for new sym in calcfirstset");
1990-10-14 09:07:46 -03:00
nsyms = 1;
sym[0] = findlabel(&g->g_ll, d->d_type, (char *)NULL);
s = &d->d_state[d->d_initial];
for (i = 0; i < s->s_narcs; i++) {
a = &s->s_arc[i];
for (j = 0; j < nsyms; j++) {
if (sym[j] == a->a_lbl)
break;
}
if (j >= nsyms) { /* New label */
sym = (int *)PyObject_REALLOC(sym,
sizeof(int) * (nsyms + 1));
1990-10-14 09:07:46 -03:00
if (sym == NULL)
1997-04-29 18:03:06 -03:00
Py_FatalError(
"no mem to resize sym in calcfirstset");
1990-10-14 09:07:46 -03:00
sym[nsyms++] = a->a_lbl;
type = l0[a->a_lbl].lb_type;
if (ISNONTERMINAL(type)) {
1997-04-29 18:03:06 -03:00
d1 = PyGrammar_FindDFA(g, type);
1990-10-14 09:07:46 -03:00
if (d1->d_first == dummy) {
fprintf(stderr,
"Left-recursion below '%s'\n",
d->d_name);
}
else {
if (d1->d_first == NULL)
calcfirstset(g, d1);
1997-04-29 18:03:06 -03:00
mergebitset(result,
d1->d_first, nbits);
1990-10-14 09:07:46 -03:00
}
}
else if (ISTERMINAL(type)) {
addbit(result, a->a_lbl);
}
}
}
d->d_first = result;
1997-04-29 18:03:06 -03:00
if (Py_DebugFlag) {
1990-10-14 09:07:46 -03:00
printf("FIRST set for '%s': {", d->d_name);
for (i = 0; i < nbits; i++) {
if (testbit(result, i))
1997-04-29 18:03:06 -03:00
printf(" %s", PyGrammar_LabelRepr(&l0[i]));
1990-10-14 09:07:46 -03:00
}
printf(" }\n");
}
PyObject_FREE(sym);
1990-10-14 09:07:46 -03:00
}