/* Computation of FIRST stets */ #include "pgenheaders.h"#include "grammar.h"#include "token.h" extern int Py_DebugFlag; /* Forward */static void calcfirstset(grammar *, dfa *); voidaddfirstsets(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 voidcalcfirstset(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 = (int *)PyObject_MALLOC(sizeof(int));	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 */			sym = (int *)PyObject_REALLOC(sym,                                                 sizeof(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");	} 	PyObject_FREE(sym);}