A data structure for TOML data that's more convenient to use than a plain dict.

toml_data.py

from typing import Iterator, Tuple, Dict, List

class MissingConfigEntry(Exception): pass

class TomlData:
	"""A better TOML data structure than a plain dict.
	Usage examples:
		data = TomlData({'x': {'y': {'z': 155}}})
		print(data['x.y.z'])   # prints 155
		data.sub('x.y')        # returns a new TomlData for {'z': 155}
		data.()                # returns (x, {}
	"""

	top = None

	def __init__(self, top_level_item: Dict[str, object]):
		assert top_level_item is not None
		self.top = top_level_item

	def __str__(self):
		print(self.top)

	def __getitem__(self, key: str):
		return self.sub(key).top

	def sub(self, key: str):
		"""Returns a new TomlData with its top set to items[1][2]..."""
		items = key.split('.')
		item = self.top
		for i, s in enumerate(items):
			if s not in item: raise MissingConfigEntry(
				"{} is not in the TOML; failed at {}"\
						.format(key, '.'.join(items[:i+1]))
			)
			item = item[s]
		return TomlData(item)


	def items(self) -> Iterator[Tuple[str, object]]:
		return self.top.items()

	def keys(self) -> Iterator[str]:
		return self.top.keys()

	def values(self) -> Iterator[object]:
		return self.top.values()

	def nested_keys(self, separator='.') -> Iterator[str]:
		for lst in self.nested_key_lists(self.top):
			yield separator.join(lst)

	def nested_key_lists(self, dictionary: Dict[str, object], prefix=None) -> Iterator[List[str]]:

		prefix = prefix[:] if prefix else []

		if isinstance(dictionary, dict):
			for key, value in dictionary.items():

				if isinstance(value, dict):
					for result in self.nested_key_lists(value, [key] + prefix): yield result
				else: yield prefix + [key]

		else: yield dictionary