def alt(self):
(first, transitions) = self.concat()
branch_node = None
# alt_tail
while self.match('|'):
(second, snd_transitions) = self.concat()
if branch_node == None:
branch_node = Node()
branch_node.add_epsilon_transition(first)
branch_node.add_epsilon_transition(second)
transitions += snd_transitions
self.append_postfix('|')
if branch_node == None:
return (first, transitions)
else:
return (branch_node, transitions)
def quant(self):
(first, transitions) = self.paren()
# quant_tail
res = self.match('+', '?', '*')
if res:
self.append_postfix(res)
if res == '*':
loop_node = Node()
for n in transitions:
n.attach_destination(loop_node)
loop_node.add_epsilon_transition(first)
transition = Transition(loop_node, None)
return (loop_node, List(transition))
elif res == '+':
loop_node = Node()
for tr in transitions:
tr.attach_destination(loop_node)
loop_node.add_epsilon_transition(first)
out_transition = Transition(loop_node, None)
return (first, List(out_transition))
elif res == '?':
skip_node = Node()
skip_node.add_epsilon_transition(first)
return (skip_node, transitions + List(Transition(skip_node, None)))
return (first, transitions)
