python 判断括号是否匹配

class StackError(Exception):
    pass


# 节点类
class Node:
    def __init__(self, val, next=None):
        self.val = val
        self.next = next


# 链式栈 *** 作
class LStack:
    def __init__(self):
        # 标记栈的栈顶位置
        self._top = None

    def is_empty(self):
        # 是否为空
        return self._top is None

    def push(self, elem):
        # 入栈
        self._top = Node(elem, self._top)

    def pop(self):
        # 出栈
        if self.is_empty():
            raise StackError('Stack is empty')
        val = self._top.val
        self._top = self._top.next
        return val

    def top(self):
        # 查看栈顶元素
        if self.is_empty():
            raise StackError('Stack is empty')
        return self._top.val


def parent(text, parens):
    # 编写生成器,用来遍历字符串,不断地提供括号及其位置
    # i 遍历字符串的索引位置
    for i in range(len(text)):
        if text[i] in parens:
            yield text[i], i


def ver(str_):
    # 将验证条件提前定义好
    parens = '()[]{}'  # 特殊处理的字符集
    left_parens = '([{'  # 入栈字符集
    # 验证匹配关系
    opposite = {'}': '{', ']': '[', ')': '('}
    # 功能函数判断提供的括号是否匹配
    print('判断内容是:', str_)
    # 存储括号的栈
    ls = LStack()
    for value, index in parent(str_, parens):
        if value in left_parens:
            # 左括号入栈
            ls.push((value, index))
        elif ls.is_empty() or ls.pop()[0] != opposite[value]:
            print('出错了第%d个位置,内容是 %s' % (index + 1, value))
            break

    else:
        if ls.is_empty():
            print('符合要求')
        else:
            print('出错了第%d个位置,内容是 %s' % (index + 1, value))


if __name__ == '__main__':
    ver('{[]{()((')