def compute_follow(grammar, first):
follow_list = []
follow_0 = Follow(0)
for n in grammar.get_nonterminals():
if n != grammar.get_start_symbol():
follow_0.set_value_symbol(n, [])
else:
follow_0.set_value_symbol(n, ["epsilon"])
follow_list.append(follow_0)
idx = 0
while True:
idx += 1
follow = Follow(idx)
for n in grammar.get_nonterminals():
f_list = []
for e in follow_list[idx - 1].get_values_for_symbol(n):
f_list.append(e)
for lhs, rhs in get_prod_with_n_rhs(n, grammar).items():
for p in rhs:
x = get_first(n, p, first)
for i in x:
if i == "epsilon":
for e in follow_list[idx -
1].get_values_for_symbol(lhs):
if e not in f_list:
f_list.append(e)
else:
if i not in f_list:
f_list.append(i)
follow.set_value_symbol(n, f_list)
follow_list.append(follow)
if compare_follows(follow_list[idx - 1], follow):
break
return follow_list[-1]
