如何解析字符串并返回嵌套数组？

Question

我想要一个带字符串并返回一个数组的Python函数，该数组中的每个项目都是字符，或者是这种类型的另一个数组。嵌套数组在输入字符串中以’（’开始，以’）’结尾。

因此，该函数将如下所示：

1) foo("abc") == ["a", "b", "c"]
2) foo("a(b)c") == ["a", ["b"], "c"]
3) foo("a(b(c))") == ["a", ["b", ["c"]]]
4) foo("a(b(c)") == error: closing bracket is missing
5) foo("a(b))c") == error: opening bracket is missing
6) foo("a)b(c") == error: opening bracket is missing

注意：我更喜欢纯功能的解决方案。

Answer 1

def foo(s):
    def foo_helper(level=0):
        try:
            token = next(tokens)
        except StopIteration:
            if level != 0:
                raise Exception('missing closing paren')
            else:
                return []
        if token == ')':
            if level == 0:
                raise Exception('missing opening paren')
            else:
                return []
        elif token == '(':
            return [foo_helper(level+1)] + foo_helper(level)
        else:
            return [token] + foo_helper(level)
    tokens = iter(s)
    return foo_helper()

和，

>>> foo('a((b(c))d)(e)')
['a', [['b', ['c']], 'd'], ['e']]