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Diffstat (limited to 'numpy/typing/_generic_alias.py')
| -rw-r--r-- | numpy/typing/_generic_alias.py | 216 |
1 files changed, 216 insertions, 0 deletions
diff --git a/numpy/typing/_generic_alias.py b/numpy/typing/_generic_alias.py new file mode 100644 index 000000000..8d65ef855 --- /dev/null +++ b/numpy/typing/_generic_alias.py @@ -0,0 +1,216 @@ +from __future__ import annotations + +import sys +import types +from typing import ( + Any, + ClassVar, + FrozenSet, + Generator, + Iterable, + Iterator, + List, + NoReturn, + Tuple, + Type, + TypeVar, + TYPE_CHECKING, +) + +import numpy as np + +__all__ = ["_GenericAlias", "NDArray"] + +_T = TypeVar("_T", bound="_GenericAlias") + + +def _to_str(obj: object) -> str: + """Helper function for `_GenericAlias.__repr__`.""" + if obj is Ellipsis: + return '...' + elif isinstance(obj, type) and not isinstance(obj, _GENERIC_ALIAS_TYPE): + if obj.__module__ == 'builtins': + return obj.__qualname__ + else: + return f'{obj.__module__}.{obj.__qualname__}' + else: + return repr(obj) + + +def _parse_parameters(args: Iterable[Any]) -> Generator[TypeVar, None, None]: + """Search for all typevars and typevar-containing objects in `args`. + + Helper function for `_GenericAlias.__init__`. + + """ + for i in args: + if hasattr(i, "__parameters__"): + yield from i.__parameters__ + elif isinstance(i, TypeVar): + yield i + + +def _reconstruct_alias(alias: _T, parameters: Iterator[TypeVar]) -> _T: + """Recursivelly replace all typevars with those from `parameters`. + + Helper function for `_GenericAlias.__getitem__`. + + """ + args = [] + for i in alias.__args__: + if isinstance(i, TypeVar): + value: Any = next(parameters) + elif isinstance(i, _GenericAlias): + value = _reconstruct_alias(i, parameters) + elif hasattr(i, "__parameters__"): + prm_tup = tuple(next(parameters) for _ in i.__parameters__) + value = i[prm_tup] + else: + value = i + args.append(value) + + cls = type(alias) + return cls(alias.__origin__, tuple(args)) + + +class _GenericAlias: + """A python-based backport of the `types.GenericAlias` class. + + E.g. for ``t = list[int]``, ``t.__origin__`` is ``list`` and + ``t.__args__`` is ``(int,)``. + + See Also + -------- + :pep:`585` + The PEP responsible for introducing `types.GenericAlias`. + + """ + + __slots__ = ("__weakref__", "_origin", "_args", "_parameters", "_hash") + + @property + def __origin__(self) -> type: + return super().__getattribute__("_origin") + + @property + def __args__(self) -> Tuple[object, ...]: + return super().__getattribute__("_args") + + @property + def __parameters__(self) -> Tuple[TypeVar, ...]: + """Type variables in the ``GenericAlias``.""" + return super().__getattribute__("_parameters") + + def __init__( + self, + origin: type, + args: object | Tuple[object, ...], + ) -> None: + self._origin = origin + self._args = args if isinstance(args, tuple) else (args,) + self._parameters = tuple(_parse_parameters(self.__args__)) + + @property + def __call__(self) -> type: + return self.__origin__ + + def __reduce__(self: _T) -> Tuple[ + Type[_T], + Tuple[type, Tuple[object, ...]], + ]: + cls = type(self) + return cls, (self.__origin__, self.__args__) + + def __mro_entries__(self, bases: Iterable[object]) -> Tuple[type]: + return (self.__origin__,) + + def __dir__(self) -> List[str]: + """Implement ``dir(self)``.""" + cls = type(self) + dir_origin = set(dir(self.__origin__)) + return sorted(cls._ATTR_EXCEPTIONS | dir_origin) + + def __hash__(self) -> int: + """Return ``hash(self)``.""" + # Attempt to use the cached hash + try: + return super().__getattribute__("_hash") + except AttributeError: + self._hash: int = hash(self.__origin__) ^ hash(self.__args__) + return super().__getattribute__("_hash") + + def __instancecheck__(self, obj: object) -> NoReturn: + """Check if an `obj` is an instance.""" + raise TypeError("isinstance() argument 2 cannot be a " + "parameterized generic") + + def __subclasscheck__(self, cls: type) -> NoReturn: + """Check if a `cls` is a subclass.""" + raise TypeError("issubclass() argument 2 cannot be a " + "parameterized generic") + + def __repr__(self) -> str: + """Return ``repr(self)``.""" + args = ", ".join(_to_str(i) for i in self.__args__) + origin = _to_str(self.__origin__) + return f"{origin}[{args}]" + + def __getitem__(self: _T, key: object | Tuple[object, ...]) -> _T: + """Return ``self[key]``.""" + key_tup = key if isinstance(key, tuple) else (key,) + + if len(self.__parameters__) == 0: + raise TypeError(f"There are no type variables left in {self}") + elif len(key_tup) > len(self.__parameters__): + raise TypeError(f"Too many arguments for {self}") + elif len(key_tup) < len(self.__parameters__): + raise TypeError(f"Too few arguments for {self}") + + key_iter = iter(key_tup) + return _reconstruct_alias(self, key_iter) + + def __eq__(self, value: object) -> bool: + """Return ``self == value``.""" + if not isinstance(value, _GENERIC_ALIAS_TYPE): + return NotImplemented + return ( + self.__origin__ == value.__origin__ and + self.__args__ == value.__args__ + ) + + _ATTR_EXCEPTIONS: ClassVar[FrozenSet[str]] = frozenset({ + "__origin__", + "__args__", + "__parameters__", + "__mro_entries__", + "__reduce__", + "__reduce_ex__", + }) + + def __getattribute__(self, name: str) -> Any: + """Return ``getattr(self, name)``.""" + # Pull the attribute from `__origin__` unless its + # name is in `_ATTR_EXCEPTIONS` + cls = type(self) + if name in cls._ATTR_EXCEPTIONS: + return super().__getattribute__(name) + return getattr(self.__origin__, name) + + +# See `_GenericAlias.__eq__` +if sys.version_info >= (3, 9): + _GENERIC_ALIAS_TYPE = (_GenericAlias, types.GenericAlias) +else: + _GENERIC_ALIAS_TYPE = (_GenericAlias,) + +ScalarType = TypeVar("ScalarType", bound=np.generic, covariant=True) + +if TYPE_CHECKING: + _DType = np.dtype[ScalarType] + NDArray = np.ndarray[Any, np.dtype[ScalarType]] +elif sys.version_info >= (3, 9): + _DType = types.GenericAlias(np.dtype, (ScalarType,)) + NDArray = types.GenericAlias(np.ndarray, (Any, _DType)) +else: + _DType = _GenericAlias(np.dtype, (ScalarType,)) + NDArray = _GenericAlias(np.ndarray, (Any, _DType)) |