recursive_fstring_interpolation.py

r"""
>>> f('''
...   [variables]
...   c = 1
...   d.e = 1
...   f = ['{g}']
...   g = ['{gg}']
...   gg = 1
...
...   [a]
...   b = 1
... ''')
{'c': 1, 'd': {'e': 1}, 'f': [[1]], 'g': [1], 'gg': 1}
"""


def f(s):
    import re
    import tomli as tomllib
    raw_config = tomllib.loads(s)
    variables = raw_config.get('variables', {})
    def expand(data, base=None):
        if base is None:
            base = data

        match data:
            case str():
                if m := re.search(r'^{(.*)}$', data):
                    return expand(eval(m.group(1), None, base), base)
                else:
                    return data
            case dict():
                return {k: expand(v, base) for k, v in data.items()}
            case list():
                return [expand(v, base) for v in data]
            case _:
                return data
    return expand(variables)