120 lines
3.2 KiB
Python
120 lines
3.2 KiB
Python
"""Handles merging with the skeleton config."""
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from typing import Dict
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class InvalidKeyError(Exception):
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"""Thrown when a config file contains an invalid key."""
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def __init__(self, key: str):
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"""Create a new InvalidKeyError object with the given key.
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Args:
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key: the invalid key
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"""
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self.message = "Invalid key: {}".format(key)
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super().__init__(key)
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class MissingKeyError(Exception):
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"""Thrown when a required key is missing from a config."""
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def __init__(self, key: str):
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"""Create a new MissingKeyError object with the given key.
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Args:
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key: the invalid key
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"""
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self.message = "Missing key: {}".format(key)
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super().__init__(key)
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def merge(*dicts: [Dict]) -> Dict:
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"""Merge multiple dicts into one.
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It reads the dicts from left to right, always preferring the "right"
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dictionary's values. Therefore, the dictionaries should be sorted from
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least important to most important (e.g. a default values skeleton should be
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to the left of a dict of selected values).
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Args:
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dicts: the dictionaries to merge
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Returns:
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a new dictionary representing the merged dictionaries
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Todo:
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* Make sure an infinite loop is not possible
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"""
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# Base cases
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if len(dicts) == 0:
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return {}
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if len(dicts) == 1:
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return dicts[0]
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# We merge the first two dicts
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d1, d2 = dicts[0], dicts[1]
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output = d1.copy()
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for key, value in d2.items():
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if type(value) == dict:
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# Merge the two sub-dictionaries
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output[key] = (
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merge(output[key], value)
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if type(output.get(key)) == dict
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else value
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)
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else:
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output[key] = value
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return merge(output, *dicts[2:])
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def merge_with_skeleton(data: Dict, skel: Dict) -> Dict:
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"""Merge a dictionary with a skeleton containing default values.
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The skeleton not only defines what the default values are, but also
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enforces a certain shape. This allows us to define a config file using a
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dictionary and parse it.
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Args:
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data: dictionary containing the selected config values
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skel: dictionary containing the skeleton (aka the def)
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Returns:
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a new dictionary representing the two merged dictionaries
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Todo:
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* Check if an infinite loop is possible
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* Split info less complex functions
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"""
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# First, check for illegal keys
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for key in data:
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if key not in skel:
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raise InvalidKeyError(key)
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# Then, check the default values
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for key, value in skel.items():
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if key not in data:
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# Raise error if there's not default value
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if value is None:
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raise MissingKeyError(key)
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# Replace with default value
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data[key] = value
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# Error if value is not same type as default value
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elif type(data[key]) != type(value) and value is not None:
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# TODO make this error message more verbose
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raise TypeError("Invalid value type")
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# Recurse into dicts
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elif type(value) == dict:
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data[key] = merge_with_skeleton(data[key], value)
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return data
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