TOML Path — A simple utility class to retrieve a specific key path in a TOML file

tomlpath.py

from os import PathLike
from functools import reduce
from operator import getitem

try:
    # Python 3.11+
    from tomllib import load, loads
except ImportError:
    from tomli import load, loads
from typing import Any, BinaryIO, Iterable, Mapping, TypeAlias, TypeGuard, Union

StrOrBytesPath: TypeAlias = str | bytes | PathLike[str] | PathLike[bytes]
_Path: TypeAlias = str
_PathParts: TypeAlias = Iterable[_Path]
_PathOrParts: TypeAlias = _Path | _PathParts


def _path_guard(__o: object) -> TypeGuard[_Path]:
    return isinstance(__o, str)


def _path_parts_guard(__o: object) -> TypeGuard[_PathParts]:
    if not isinstance(__o, Iterable):
        return False

    return all(_path_guard(member) for member in __o)


class TOMLPath:
    parts: tuple[str, ...]

    def __init__(self, path_or_parts: _PathOrParts, separator: str = ".") -> None:
        if _path_guard(path_or_parts):
            self.parts = tuple(path_or_parts.split(separator))
            return
        if _path_parts_guard(path_or_parts):
            self.parts = tuple(path_or_parts)
            return

        raise ValueError(
            "TOMLPath requires a path string or an iterable returning the path keys"
        )

    def get_from_file(self, path: StrOrBytesPath | int) -> Any:
        with open(path, "rb") as fp:
            return self.get(parsed=load(fp))

    def get_from_fp(self, file_pointer: BinaryIO) -> Any:
        return self.get(parsed=load(file_pointer))

    def get_from_str(self, content: str) -> Any:
        return self.get(parsed=loads(content))

    def get(self, parsed: Mapping[str, Any]) -> Any:
        return reduce(getitem, self.parts, parsed)