mirror of
https://github.com/python/cpython.git
synced 2024-11-28 16:45:42 +01:00
110 lines
2.1 KiB
C
110 lines
2.1 KiB
C
|
|
/* Computation of FIRST stets */
|
|
|
|
#include "pgenheaders.h"
|
|
#include "grammar.h"
|
|
#include "token.h"
|
|
|
|
extern int Py_DebugFlag;
|
|
|
|
/* Forward */
|
|
static void calcfirstset(grammar *, dfa *);
|
|
|
|
void
|
|
addfirstsets(grammar *g)
|
|
{
|
|
int i;
|
|
dfa *d;
|
|
|
|
printf("Adding FIRST sets ...\n");
|
|
for (i = 0; i < g->g_ndfas; i++) {
|
|
d = &g->g_dfa[i];
|
|
if (d->d_first == NULL)
|
|
calcfirstset(g, d);
|
|
}
|
|
}
|
|
|
|
static void
|
|
calcfirstset(grammar *g, dfa *d)
|
|
{
|
|
int i, j;
|
|
state *s;
|
|
arc *a;
|
|
int nsyms;
|
|
int *sym;
|
|
int nbits;
|
|
static bitset dummy;
|
|
bitset result;
|
|
int type;
|
|
dfa *d1;
|
|
label *l0;
|
|
|
|
if (Py_DebugFlag)
|
|
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 = PyMem_NEW(int, 1);
|
|
if (sym == NULL)
|
|
Py_FatalError("no mem for new sym in calcfirstset");
|
|
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 */
|
|
PyMem_RESIZE(sym, int, nsyms + 1);
|
|
if (sym == NULL)
|
|
Py_FatalError(
|
|
"no mem to resize sym in calcfirstset");
|
|
sym[nsyms++] = a->a_lbl;
|
|
type = l0[a->a_lbl].lb_type;
|
|
if (ISNONTERMINAL(type)) {
|
|
d1 = PyGrammar_FindDFA(g, type);
|
|
if (d1->d_first == dummy) {
|
|
fprintf(stderr,
|
|
"Left-recursion below '%s'\n",
|
|
d->d_name);
|
|
}
|
|
else {
|
|
if (d1->d_first == NULL)
|
|
calcfirstset(g, d1);
|
|
mergebitset(result,
|
|
d1->d_first, nbits);
|
|
}
|
|
}
|
|
else if (ISTERMINAL(type)) {
|
|
addbit(result, a->a_lbl);
|
|
}
|
|
}
|
|
}
|
|
d->d_first = result;
|
|
if (Py_DebugFlag) {
|
|
printf("FIRST set for '%s': {", d->d_name);
|
|
for (i = 0; i < nbits; i++) {
|
|
if (testbit(result, i))
|
|
printf(" %s", PyGrammar_LabelRepr(&l0[i]));
|
|
}
|
|
printf(" }\n");
|
|
}
|
|
}
|