Initial revision
diff --git a/Parser/firstsets.c b/Parser/firstsets.c
new file mode 100644
index 0000000..0f28dd0
--- /dev/null
+++ b/Parser/firstsets.c
@@ -0,0 +1,109 @@
+/* Computation of FIRST stets */
+
+#include <stdio.h>
+
+#include "PROTO.h"
+#include "malloc.h"
+#include "grammar.h"
+#include "token.h"
+
+extern int debugging;
+
+static void
+calcfirstset(g, d)
+ 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 (debugging)
+ 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 = NEW(int, 1);
+ if (sym == NULL)
+ fatal("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 */
+ RESIZE(sym, int, nsyms + 1);
+ if (sym == NULL)
+ fatal("no mem to resize sym in calcfirstset");
+ sym[nsyms++] = a->a_lbl;
+ type = l0[a->a_lbl].lb_type;
+ if (ISNONTERMINAL(type)) {
+ d1 = 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 (debugging) {
+ printf("FIRST set for '%s': {", d->d_name);
+ for (i = 0; i < nbits; i++) {
+ if (testbit(result, i))
+ printf(" %s", labelrepr(&l0[i]));
+ }
+ printf(" }\n");
+ }
+}
+
+void
+addfirstsets(g)
+ 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);
+ }
+}