You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
110 lines
2.2 KiB
110 lines
2.2 KiB
|
|
/* 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; |
|
|
|
if (Py_DebugFlag) |
|
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"); |
|
} |
|
}
|
|
|