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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 = 0;
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;
}
}
}
}
}
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