def concatenate_nfa(self):
nfa_last = self.nfa_stack.pop()
nfa_first = self.nfa_stack.pop()
nfa_first.end.accept = False
nfa_first.end.epsilon.append(nfa_last.start)
nfa = NFA(nfa_first.start, nfa_last.end)
self.nfa_stack.append(nfa)
def char_nfa(self, token):
start_status = Status()
end_status = Status()
start_status.translate(token.value, end_status)
end_status.accept = True
nfa = NFA(start_status, end_status)
self.nfa_stack.append(nfa)
def plus_nfa(self):
start_status = Status()
end_status = Status()
end_status.accept = True
nfa = self.nfa_stack.pop()
nfa.end.accept = False
nfa.end.epsilon.append(nfa.start)
start_status.epsilon.append(nfa.start)
nfa.end.epsilon.append(end_status)
self.nfa_stack.append(NFA(start_status, end_status))
def bar_nfa(self):
nfa_last = self.nfa_stack.pop()
nfa_first = self.nfa_stack.pop()
start_status = Status()
end_status = Status()
end_status.accept = True
start_status.epsilon.append(nfa_first.start)
start_status.epsilon.append(nfa_last.start)
nfa_first.end.epsilon.append(end_status)
nfa_last.end.epsilon.append(end_status)
nfa_first.end.accept = False
nfa_last.end.accept = False
nfa = NFA(start_status, end_status)
self.nfa_stack.append(nfa)
def reverse(self):
# reset Status count
Status.count = 0
end_status = Status()
end_status.accept = True
accept_status_list = []
status_list = {self.dfa.start: end_status}
work_list = [self.dfa.start]
while work_list:
status = work_list.pop()
new_status = status_list[status]
if status not in self.dfa.table:
# this status gos no where
continue
for k, v in self.dfa.table[status].items():
sub_status = None
if v not in status_list:
sub_status = Status()
if v.accept:
accept_status_list.append(sub_status)
status_list.update({v: sub_status})
work_list.append(v)
else:
sub_status = status_list[v]
sub_status.translate(k, new_status)
start_status = Status()
start_status.epsilon = accept_status_list
return NFA(start_status, end_status)