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65 lines
2.3 KiB
Python
65 lines
2.3 KiB
Python
# This file is derived from github.com/ericvsmith/dataclasses, and is Apache 2 licensed.
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# https://github.com/ericvsmith/dataclasses/blob/ae712dd993420d43444f188f452/LICENSE.txt
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# https://github.com/ericvsmith/dataclasses/blob/ae712dd993420d43444f/dataclass_tools.py
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# Changed: takes slots in base classes into account when creating slots
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import dataclasses
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from itertools import chain, filterfalse
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from typing import Any, Mapping, Type, TypeVar
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_T = TypeVar("_T")
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def add_slots(cls: Type[_T]) -> Type[_T]:
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# Need to create a new class, since we can't set __slots__
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# after a class has been created.
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# Make sure __slots__ isn't already set.
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if "__slots__" in cls.__dict__:
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raise TypeError(f"{cls.__name__} already specifies __slots__")
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# Create a new dict for our new class.
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cls_dict = dict(cls.__dict__)
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field_names = tuple(f.name for f in dataclasses.fields(cls))
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inherited_slots = set(
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chain.from_iterable(
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superclass.__dict__.get("__slots__", ()) for superclass in cls.mro()
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)
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)
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cls_dict["__slots__"] = tuple(
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filterfalse(inherited_slots.__contains__, field_names)
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)
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for field_name in field_names:
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# Remove our attributes, if present. They'll still be
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# available in _MARKER.
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cls_dict.pop(field_name, None)
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# Remove __dict__ itself.
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cls_dict.pop("__dict__", None)
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# Create the class.
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qualname = getattr(cls, "__qualname__", None)
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# pyre-fixme[9]: cls has type `Type[Variable[_T]]`; used as `_T`.
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# pyre-fixme[19]: Expected 0 positional arguments.
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cls = type(cls)(cls.__name__, cls.__bases__, cls_dict)
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if qualname is not None:
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cls.__qualname__ = qualname
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# Set __getstate__ and __setstate__ to workaround a bug with pickling frozen
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# dataclasses with slots. See https://bugs.python.org/issue36424
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def __getstate__(self: object) -> Mapping[str, Any]:
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return {
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field.name: getattr(self, field.name)
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for field in dataclasses.fields(self)
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if hasattr(self, field.name)
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}
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def __setstate__(self: object, state: Mapping[str, Any]) -> None:
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for fieldname, value in state.items():
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object.__setattr__(self, fieldname, value)
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cls.__getstate__ = __getstate__
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cls.__setstate__ = __setstate__
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return cls
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