1 files changed, 95 insertions, 0 deletions
diff --git a/utils/Burg/closure.c b/utils/Burg/closure.c
new file mode 100644
index 0000000..70e1626
--- /dev/null
+++ b/utils/Burg/closure.c
@@ -0,0 +1,95 @@
+char rcsid_closure[] = "$Id$";
+
+#include <stdio.h>
+#include "b.h"
+
+int prevent_divergence = 0;
+
+List chainrules;
+
+void
+findChainRules()
+{
+	List pl;
+
+	assert(!chainrules);
+
+	for (pl = rules; pl; pl = pl->next) {
+		Rule p = (Rule) pl->x;
+		if (!p->pat->op) {
+			chainrules = newList(p, chainrules);
+		} else {
+			p->pat->op->table->rules = newList(p, p->pat->op->table->rules);
+			addRelevant(p->pat->op->table->relevant, p->lhs->num);
+		}
+	}
+}
+
+void
+zero(t) Item_Set t;
+{
+	int i;
+	DeltaCost base;
+	int exists;
+	int base_nt;
+
+	assert(!t->closed);
+
+	ZEROCOST(base);
+	exists = 0;
+	for (i = 0; i < max_nonterminal; i++) {
+		if (t->virgin[i].rule) {
+			if (exists) {
+				if (LESSCOST(t->virgin[i].delta, base)) {
+					ASSIGNCOST(base, t->virgin[i].delta);
+					base_nt = i;
+				}
+			} else {
+				ASSIGNCOST(base, t->virgin[i].delta);
+				exists = 1;
+				base_nt = i;
+			}
+		}
+	}
+	if (!exists) {
+		return;
+	}
+	for (i = 0; i < max_nonterminal; i++) {
+		if (t->virgin[i].rule) {
+			MINUSCOST(t->virgin[i].delta, base);
+		}
+		NODIVERGE(t->virgin[i].delta, t, i, base_nt);
+	}
+}
+
+void
+closure(t) Item_Set t;
+{
+	int changes;
+	List pl;
+
+	assert(!t->closed);
+	t->closed = itemArrayCopy(t->virgin);
+
+	changes = 1;
+	while (changes) {
+		changes = 0;
+		for (pl = chainrules; pl; pl = pl->next) {
+			Rule p = (Rule) pl->x;
+			register Item *rhs_item = &t->closed[p->pat->children[0]->num];
+
+			if (rhs_item->rule) {	/* rhs is active */
+				DeltaCost dc;
+				register Item *lhs_item = &t->closed[p->lhs->num];
+
+				ASSIGNCOST(dc, rhs_item->delta);
+				ADDCOST(dc, p->delta);
+				if (LESSCOST(dc, lhs_item->delta) || !lhs_item->rule) {
+					ASSIGNCOST(lhs_item->delta, dc);
+					lhs_item->rule = p;
+					changes = 1;
+				}
+			}
+		}
+	}
+}