编写一个可以将正规式:((ab)|b)(a|(ba)*)a转化为NFA图的python代码
时间: 2023-12-14 10:39:24 浏览: 39
以下是一个简单的 Python 代码,可以将给定的正则表达式转换为 NFA 图:
```python
class State:
def __init__(self, label=None, edges=None):
self.label = label
self.edges = edges or []
class Fragment:
def __init__(self, start, accept):
self.start = start
self.accept = accept
def re_to_nfa(regex):
stack = []
for c in regex:
if c == '(':
stack.append(c)
elif c == ')':
while stack[-1] != '(':
r = stack.pop()
if r == '|':
frag2 = stack.pop()
frag1 = stack.pop()
frag1.accept.edges.append(frag2.start)
stack.append(Fragment(frag1.start, frag2.accept))
else:
frag = stack.pop()
r.accept.edges.append(frag.start)
stack.append(Fragment(r.start, frag.accept))
stack.pop()
elif c == '|':
stack.append(c)
else:
s = State()
t = State()
s.edges.append(t)
s.label = c
stack.append(Fragment(s, t))
while len(stack) > 1:
frag2 = stack.pop()
frag1 = stack.pop()
frag1.accept.edges.append(frag2.start)
stack.append(Fragment(frag1.start, frag2.accept))
return stack[0]
nfa = re_to_nfa("((ab)|b)(a|(ba)*)a")
```
这个代码使用了栈来处理正则表达式,每次从栈中弹出元素并进行操作,最终返回一个 NFA 图。