Simple function for recursively iterating JSON-like data in Python

recurse_object.py

from collections.abc import Mapping
from typing import Any, Callable, Iterable, MutableMapping, MutableSequence


def recurse_object(o: Any,
                   k=None,
                   fn: Callable[[Any,Any,Any],Any]=None,
                   prefn:Callable[[Any,Any],None]=None,
                   postfn:Callable[[Any,Any,Any,Any],Any]=None,
                   mapping_cls=dict,
                   sequence_cls=list) -> Any:
    """
    Recurse through an object and apply a function to every key level.
    Only applicable to Mapping/Sequence types.

    :param o: (any) object to recurse through
    :param k: (any) key path of the value that provided the object just requested
    :param fn: fn which manipulates the value
    :param prefn: prefn called before recursing
    :param postfn: postfn called before returning
    :param mapping_cls: class initializer for mapping types
    :param sequence_cls: class initializer for sequence types
    :return:
    """
    if fn is None:
        fn = lambda i, k, o: i

    if prefn is not None:
        i = prefn(o,k)
    else:
        i = o

    r: Any = None

    if isinstance(i, Mapping):
        r: MutableMapping = mapping_cls()
        for k,v in i.items():
            r[k] = recurse_object(v, k, fn=fn, prefn=prefn, postfn=postfn)
    elif isinstance(i, Iterable) and not isinstance(i, (str,bytes)):
        r: MutableSequence = sequence_cls()
        for k,v in enumerate(i):
            r.append(recurse_object(v, k, fn=fn, prefn=prefn, postfn=postfn))
    else:
        r = fn(i,k,o)

    if postfn is not None:
        r = postfn(o,k,i,r)

    return r