在python中构建区分大小写的字典

class CaseInsensitiveDict(dict):
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self._key_map = {}

    def __setitem__(self, key, value):
        normalized_key = key.lower()
        self._key_map[normalized_key] = key
        super().__setitem__(normalized_key, value)

    def __getitem__(self, key):
        normalized_key = key.lower()
        real_key = self._key_map.get(normalized_key)
        if real_key is None:
            raise KeyError(key)
        return super().__getitem__(normalized_key)

    def __delitem__(self, key):
        normalized_key = key.lower()
        real_key = self._key_map.pop(normalized_key, None)
        if real_key is None:
            raise KeyError(key)
        super().__delitem__(normalized_key)

    def __contains__(self, key):
        normalized_key = key.lower()
        return normalized_key in self._key_map

    def keys(self):
        return self._key_map.values()

    def items(self):
        return ((real_key, self[real_key]) for real_key in self.keys())

    def values(self):
        return (self[real_key] for real_key in self.keys())

d = CaseInsensitiveDict()
d['Key'] = 'Value'
print(d['key'])  # 输出：Value
print('Key' in d)  # 输出：True
print(list(d.keys()))  # 输出：['Key']