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import json
from contextlib import suppress
from pathlib import PurePath
from typing import Any, Callable, Dict, List, Optional, Tuple
from .registry import _import_class, get_filesystem_class
from .spec import AbstractFileSystem
class FilesystemJSONEncoder(json.JSONEncoder):
def default(self, o: Any) -> Any:
if isinstance(o, AbstractFileSystem):
return o.to_dict()
if isinstance(o, PurePath):
cls = type(o)
return {"cls": f"{cls.__module__}.{cls.__name__}", "str": str(o)}
return super().default(o)
class FilesystemJSONDecoder(json.JSONDecoder):
def __init__(
self,
*,
object_hook: Optional[Callable[[Dict[str, Any]], Any]] = None,
parse_float: Optional[Callable[[str], Any]] = None,
parse_int: Optional[Callable[[str], Any]] = None,
parse_constant: Optional[Callable[[str], Any]] = None,
strict: bool = True,
object_pairs_hook: Optional[Callable[[List[Tuple[str, Any]]], Any]] = None,
) -> None:
self.original_object_hook = object_hook
super().__init__(
object_hook=self.custom_object_hook,
parse_float=parse_float,
parse_int=parse_int,
parse_constant=parse_constant,
strict=strict,
object_pairs_hook=object_pairs_hook,
)
@classmethod
def try_resolve_path_cls(cls, dct: Dict[str, Any]):
with suppress(Exception):
fqp = dct["cls"]
path_cls = _import_class(fqp)
if issubclass(path_cls, PurePath):
return path_cls
return None
@classmethod
def try_resolve_fs_cls(cls, dct: Dict[str, Any]):
with suppress(Exception):
if "cls" in dct:
try:
fs_cls = _import_class(dct["cls"])
if issubclass(fs_cls, AbstractFileSystem):
return fs_cls
except Exception:
if "protocol" in dct: # Fallback if cls cannot be imported
return get_filesystem_class(dct["protocol"])
raise
return None
def custom_object_hook(self, dct: Dict[str, Any]):
if "cls" in dct:
if (obj_cls := self.try_resolve_fs_cls(dct)) is not None:
return AbstractFileSystem.from_dict(dct)
if (obj_cls := self.try_resolve_path_cls(dct)) is not None:
return obj_cls(dct["str"])
if self.original_object_hook is not None:
return self.original_object_hook(dct)
return dct