71 lines
2.3 KiB
Python
Executable File
71 lines
2.3 KiB
Python
Executable File
"""Implement a tiny subset of dataclasses_json for config."""
|
|
from collections.abc import Mapping, Sequence
|
|
from dataclasses import asdict, fields, is_dataclass
|
|
from typing import Any, Dict, Type
|
|
|
|
|
|
class DataClassJsonMixin:
|
|
"""Adds from_dict to dataclass."""
|
|
|
|
@classmethod
|
|
def from_dict(cls, data: Dict[str, Any]) -> Any:
|
|
"""Parse dataclasses recursively."""
|
|
kwargs: Dict[str, Any] = {}
|
|
|
|
cls_fields = {field.name: field for field in fields(cls)}
|
|
for key, value in data.items():
|
|
if key not in cls_fields:
|
|
# Skip unknown fields
|
|
continue
|
|
|
|
field = cls_fields[key]
|
|
if is_dataclass(field.type):
|
|
assert issubclass(field.type, DataClassJsonMixin), field.type
|
|
kwargs[key] = field.type.from_dict(value)
|
|
else:
|
|
kwargs[key] = _decode(value, field.type)
|
|
|
|
# Fill in optional fields with None
|
|
for field in cls_fields.values():
|
|
if (field.name not in kwargs) and _is_optional(field.type):
|
|
kwargs[field.name] = None
|
|
|
|
return cls(**kwargs)
|
|
|
|
def to_dict(self) -> Dict[str, Any]:
|
|
"""Alias for asdict."""
|
|
return asdict(self)
|
|
|
|
|
|
def _decode(value: Any, target_type: Type) -> Any:
|
|
"""Decode value using (possibly generic) type."""
|
|
if is_dataclass(target_type):
|
|
assert issubclass(target_type, DataClassJsonMixin), target_type
|
|
return target_type.from_dict(value) if value is not None else None
|
|
|
|
if hasattr(target_type, "__args__"):
|
|
# Optional[T]
|
|
if type(None) in target_type.__args__:
|
|
optional_type = target_type.__args__[0]
|
|
return _decode(value, optional_type)
|
|
|
|
# List[T]
|
|
if isinstance(value, Sequence):
|
|
list_type = target_type.__args__[0]
|
|
return [_decode(item, list_type) for item in value]
|
|
|
|
# Dict[str, T]
|
|
if isinstance(value, Mapping):
|
|
value_type = target_type.__args__[1]
|
|
return {
|
|
map_key: _decode(map_value, value_type)
|
|
for map_key, map_value in value.items()
|
|
}
|
|
|
|
return value
|
|
|
|
|
|
def _is_optional(target_type: Type):
|
|
"""True if type is Optional"""
|
|
return hasattr(target_type, "__args__") and (type(None) in target_type.__args__)
|