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"""
Backport Python3.8+ typing utils & issubtype & more
![Python 3.6](https://github.com/bojiang/typing_utils/workflows/Python%203.6/badge.svg)
![Python 3.7](https://github.com/bojiang/typing_utils/workflows/Python%203.7/badge.svg)
![Python 3.8](https://github.com/bojiang/typing_utils/workflows/Python%203.8/badge.svg)
## Install
``` bash
pip install typing_utils
```
"""
import collections.abc
import io
import itertools
import types
import typing
if hasattr(typing, "ForwardRef"): # python3.8
ForwardRef = getattr(typing, "ForwardRef")
elif hasattr(typing, "_ForwardRef"): # python3.6
ForwardRef = getattr(typing, "_ForwardRef")
else:
raise NotImplementedError()
if hasattr(typing, "Literal"):
Literal = getattr(typing, "Literal")
else:
Literal = None
if hasattr(typing, "_TypedDictMeta"):
_TypedDictMeta = getattr(typing, "_TypedDictMeta")
else:
_TypedDictMeta = None
if hasattr(types, "UnionType"):
UnionType = getattr(types, "UnionType")
else:
UnionType = None
unknown = None
BUILTINS_MAPPING = {
typing.List: list,
typing.Set: set,
typing.Dict: dict,
typing.Tuple: tuple,
typing.ByteString: bytes, # https://docs.python.org/3/library/typing.html#typing.ByteString
typing.Callable: collections.abc.Callable,
typing.Sequence: collections.abc.Sequence,
type(None): None,
}
STATIC_SUBTYPE_MAPPING: typing.Dict[type, typing.Type] = {
io.TextIOWrapper: typing.TextIO,
io.TextIOBase: typing.TextIO,
io.StringIO: typing.TextIO,
io.BufferedReader: typing.BinaryIO,
io.BufferedWriter: typing.BinaryIO,
io.BytesIO: typing.BinaryIO,
}
if UnionType:
def is_union(element: object) -> bool:
return element is typing.Union or element is UnionType
else:
def is_union(element: object) -> bool:
return element is typing.Union
def optional_all(elements) -> typing.Optional[bool]:
if all(elements):
return True
if all(e is False for e in elements):
return False
return unknown
def optional_any(elements) -> typing.Optional[bool]:
if any(elements):
return True
if any(e is None for e in elements):
return unknown
return False
def _hashable(value):
"""Determine whether `value` can be hashed."""
try:
hash(value)
except TypeError:
return False
return True
get_type_hints = typing.get_type_hints
GenericClass = type(typing.List)
UnionClass = type(typing.Union)
Type = typing.Union[None, type, "typing.TypeVar"]
OriginType = typing.Union[None, type]
TypeArgs = typing.Union[type, typing.AbstractSet[type], typing.Sequence[type]]
def _normalize_aliases(type_: Type) -> Type:
if isinstance(type_, typing.TypeVar):
return type_
assert _hashable(type_), "_normalize_aliases should only be called on element types"
if type_ in BUILTINS_MAPPING:
return BUILTINS_MAPPING[type_] # type: ignore
return type_
def get_origin(type_):
"""Get the unsubscripted version of a type.
This supports generic types, Callable, Tuple, Union, Literal, Final and ClassVar.
Return None for unsupported types.
Examples:
```python
from typing_utils import get_origin
get_origin(Literal[42]) is Literal
get_origin(int) is None
get_origin(ClassVar[int]) is ClassVar
get_origin(Generic) is Generic
get_origin(Generic[T]) is Generic
get_origin(Union[T, int]) is Union
get_origin(List[Tuple[T, T]][int]) == list
```
"""
if hasattr(typing, "get_origin"): # python 3.8+
_getter = getattr(typing, "get_origin")
ori = _getter(type_)
elif hasattr(typing.List, "_special"): # python 3.7
if isinstance(type_, GenericClass) and not type_._special:
ori = type_.__origin__
elif hasattr(type_, "_special") and type_._special:
ori = type_
elif type_ is typing.Generic:
ori = typing.Generic
else:
ori = None
else: # python 3.6
if isinstance(type_, GenericClass):
ori = type_.__origin__
if ori is None:
ori = type_
elif isinstance(type_, UnionClass):
ori = type_.__origin__
elif type_ is typing.Generic:
ori = typing.Generic
else:
ori = None
if ori is None and _TypedDictMeta and isinstance(type_, _TypedDictMeta):
ori = dict
return _normalize_aliases(ori)
def get_args(type_) -> typing.Tuple:
"""Get type arguments with all substitutions performed.
For unions, basic simplifications used by Union constructor are performed.
Examples:
```python
from typing_utils import get_args
get_args(Dict[str, int]) == (str, int)
get_args(int) == ()
get_args(Union[int, Union[T, int], str][int]) == (int, str)
get_args(Union[int, Tuple[T, int]][str]) == (int, Tuple[str, int])
get_args(Callable[[], T][int]) == ([], int)
```
"""
if hasattr(typing, "get_args"): # python 3.8+
_getter = getattr(typing, "get_args")
res = _getter(type_)
elif hasattr(typing.List, "_special"): # python 3.7
if (
isinstance(type_, GenericClass) and not type_._special # type: ignore
): # backport for python 3.8
res = type_.__args__ # type: ignore
if get_origin(type_) is collections.abc.Callable and res[0] is not Ellipsis:
res = (list(res[:-1]), res[-1])
else:
res = ()
else: # python 3.6
if isinstance(type_, (GenericClass, UnionClass)): # backport for python 3.8
res = type_.__args__ # type: ignore
if get_origin(type_) is collections.abc.Callable and res[0] is not Ellipsis:
res = (list(res[:-1]), res[-1])
else:
res = ()
if _TypedDictMeta and isinstance(type_, _TypedDictMeta):
return str, typing.Any
return () if res is None else res
def eval_forward_ref(ref, forward_refs=None):
"""
eval forward_refs in all cPython versions
"""
localns = forward_refs or {}
if hasattr(typing, "_eval_type"): # python3.8 & python 3.9
_eval_type = getattr(typing, "_eval_type")
return _eval_type(ref, globals(), localns)
if hasattr(ref, "_eval_type"): # python3.6
_eval_type = getattr(ref, "_eval_type")
return _eval_type(globals(), localns)
raise NotImplementedError()
class NormalizedType(typing.NamedTuple):
"""
Normalized type, made it possible to compare, hash between types.
"""
origin: Type
args: typing.Union[tuple, frozenset] = tuple()
def __eq__(self, other):
if isinstance(other, NormalizedType):
if self.origin != other.origin:
return False
if isinstance(self.args, frozenset) and isinstance(other.args, frozenset):
return self.args <= other.args and other.args <= self.args
return self.origin == other.origin and self.args == other.args
if not self.args:
return self.origin == other
return False
def __hash__(self) -> int:
if not self.args:
return hash(self.origin)
return hash((self.origin, self.args))
def __repr__(self):
if not self.args:
return f"{self.origin}"
return f"{self.origin}[{self.args}])"
def _normalize_args(tps: TypeArgs):
if isinstance(tps, str):
return tps
if isinstance(tps, collections.abc.Sequence):
return tuple(_normalize_args(type_) for type_ in tps)
if isinstance(tps, collections.abc.Set):
return frozenset(_normalize_args(type_) for type_ in tps)
return normalize(tps)
def normalize(type_: Type) -> NormalizedType:
"""
convert types to NormalizedType instances.
"""
args = get_args(type_)
origin = get_origin(type_)
if not origin:
return NormalizedType(_normalize_aliases(type_))
origin = _normalize_aliases(origin)
if is_union(origin): # sort args when the origin is Union
args = _normalize_args(frozenset(args))
else:
args = _normalize_args(args)
return NormalizedType(origin, args)
def _is_origin_subtype(left: OriginType, right: OriginType) -> bool:
if left is right:
return True
if (
left is not None
and left in STATIC_SUBTYPE_MAPPING
and right == STATIC_SUBTYPE_MAPPING[left]
):
return True
if hasattr(left, "mro"):
for parent in left.mro(): # type: ignore
if parent == right:
return True
if isinstance(left, type) and isinstance(right, type):
return issubclass(left, right)
return left == right
NormalizedTypeArgs = typing.Union[
typing.Tuple[typing.Any, ...],
typing.FrozenSet[NormalizedType],
NormalizedType,
]
def _is_origin_subtype_args(
left: "NormalizedTypeArgs",
right: "NormalizedTypeArgs",
forward_refs: typing.Optional[typing.Mapping[str, type]],
) -> typing.Optional[bool]:
if isinstance(left, frozenset):
if not isinstance(right, frozenset):
return False
excluded = left - right
if not excluded:
# Union[str, int] <> Union[int, str]
return True
# Union[list, int] <> Union[typing.Sequence, int]
return all(
any(_is_normal_subtype(e, r, forward_refs) for r in right) for e in excluded
)
if isinstance(left, collections.abc.Sequence) and not isinstance(
left, NormalizedType
):
if not isinstance(right, collections.abc.Sequence) or isinstance(
right, NormalizedType
):
return False
if (
left
and left[-1].origin is not Ellipsis
and right
and right[-1].origin is Ellipsis
):
# Tuple[type, type] <> Tuple[type, ...]
return all(_is_origin_subtype_args(l, right[0], forward_refs) for l in left)
if len(left) != len(right):
return False
return all(
l is not None
and r is not None
and _is_origin_subtype_args(l, r, forward_refs)
for l, r in itertools.zip_longest(left, right)
)
assert isinstance(left, NormalizedType)
assert isinstance(right, NormalizedType)
return _is_normal_subtype(left, right, forward_refs)
def _is_normal_subtype(
left: NormalizedType,
right: NormalizedType,
forward_refs: typing.Optional[typing.Mapping[str, type]],
) -> typing.Optional[bool]:
if isinstance(left.origin, ForwardRef):
left = normalize(eval_forward_ref(left.origin, forward_refs=forward_refs))
if isinstance(right.origin, ForwardRef):
right = normalize(eval_forward_ref(right.origin, forward_refs=forward_refs))
# Any
if right.origin is typing.Any:
return True
# Union
if is_union(right.origin) and is_union(left.origin):
return _is_origin_subtype_args(left.args, right.args, forward_refs)
if is_union(right.origin):
return optional_any(
_is_normal_subtype(left, a, forward_refs) for a in right.args
)
if is_union(left.origin):
return optional_all(
_is_normal_subtype(a, right, forward_refs) for a in left.args
)
# Literal
if right.origin is Literal:
if left.origin is not Literal:
return False
return set(left.args).issubset(set(right.args))
# TypeVar
if isinstance(left.origin, typing.TypeVar) and isinstance(
right.origin, typing.TypeVar
):
if left.origin is right.origin:
return True
left_bound = getattr(left.origin, "__bound__", None)
right_bound = getattr(right.origin, "__bound__", None)
if right_bound is None or left_bound is None:
return unknown
return _is_normal_subtype(
normalize(left_bound), normalize(right_bound), forward_refs
)
if isinstance(right.origin, typing.TypeVar):
return unknown
if isinstance(left.origin, typing.TypeVar):
left_bound = getattr(left.origin, "__bound__", None)
if left_bound is None:
return unknown
return _is_normal_subtype(normalize(left_bound), right, forward_refs)
if not left.args and not right.args:
return _is_origin_subtype(left.origin, right.origin)
if not right.args:
return _is_origin_subtype(left.origin, right.origin)
if _is_origin_subtype(left.origin, right.origin):
return _is_origin_subtype_args(left.args, right.args, forward_refs)
return False
def issubtype(
left: Type,
right: Type,
forward_refs: typing.Optional[dict] = None,
) -> typing.Optional[bool]:
"""Check that the left argument is a subtype of the right.
For unions, check if the type arguments of the left is a subset of the right.
Also works for nested types including ForwardRefs.
Examples:
```python
from typing_utils import issubtype
issubtype(typing.List, typing.Any) == True
issubtype(list, list) == True
issubtype(list, typing.List) == True
issubtype(list, typing.Sequence) == True
issubtype(typing.List[int], list) == True
issubtype(typing.List[typing.List], list) == True
issubtype(list, typing.List[int]) == False
issubtype(list, typing.Union[typing.Tuple, typing.Set]) == False
issubtype(typing.List[typing.List], typing.List[typing.Sequence]) == True
JSON = typing.Union[
int, float, bool, str, None, typing.Sequence["JSON"],
typing.Mapping[str, "JSON"]
]
issubtype(str, JSON, forward_refs={'JSON': JSON}) == True
issubtype(typing.Dict[str, str], JSON, forward_refs={'JSON': JSON}) == True
issubtype(typing.Dict[str, bytes], JSON, forward_refs={'JSON': JSON}) == False
```
"""
return _is_normal_subtype(normalize(left), normalize(right), forward_refs)
__all__ = [
"issubtype",
"get_origin",
"get_args",
"get_type_hints",
]