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# Licensed under the LGPL: https://www.gnu.org/licenses/old-licenses/lgpl-2.1.en.html
# For details: https://github.com/PyCQA/astroid/blob/main/LICENSE
# Copyright (c) https://github.com/PyCQA/astroid/blob/main/CONTRIBUTORS.txt
"""Astroid hooks for typing.py support."""
from __future__ import annotations
import sys
import typing
from collections.abc import Iterator
from functools import partial
from astroid import context, extract_node, inference_tip
from astroid.builder import _extract_single_node
from astroid.const import PY38_PLUS, PY39_PLUS
from astroid.exceptions import (
AttributeInferenceError,
InferenceError,
UseInferenceDefault,
)
from astroid.manager import AstroidManager
from astroid.nodes.node_classes import (
Assign,
AssignName,
Attribute,
Call,
Const,
JoinedStr,
Name,
NodeNG,
Subscript,
Tuple,
)
from astroid.nodes.scoped_nodes import ClassDef, FunctionDef
if sys.version_info >= (3, 8):
from typing import Final
else:
from typing_extensions import Final
TYPING_TYPEVARS = {"TypeVar", "NewType"}
TYPING_TYPEVARS_QUALIFIED: Final = {
"typing.TypeVar",
"typing.NewType",
"typing_extensions.TypeVar",
}
TYPING_TYPEDDICT_QUALIFIED: Final = {"typing.TypedDict", "typing_extensions.TypedDict"}
TYPING_TYPE_TEMPLATE = """
class Meta(type):
def __getitem__(self, item):
return self
@property
def __args__(self):
return ()
class {0}(metaclass=Meta):
pass
"""
TYPING_MEMBERS = set(getattr(typing, "__all__", []))
TYPING_ALIAS = frozenset(
(
"typing.Hashable",
"typing.Awaitable",
"typing.Coroutine",
"typing.AsyncIterable",
"typing.AsyncIterator",
"typing.Iterable",
"typing.Iterator",
"typing.Reversible",
"typing.Sized",
"typing.Container",
"typing.Collection",
"typing.Callable",
"typing.AbstractSet",
"typing.MutableSet",
"typing.Mapping",
"typing.MutableMapping",
"typing.Sequence",
"typing.MutableSequence",
"typing.ByteString",
"typing.Tuple",
"typing.List",
"typing.Deque",
"typing.Set",
"typing.FrozenSet",
"typing.MappingView",
"typing.KeysView",
"typing.ItemsView",
"typing.ValuesView",
"typing.ContextManager",
"typing.AsyncContextManager",
"typing.Dict",
"typing.DefaultDict",
"typing.OrderedDict",
"typing.Counter",
"typing.ChainMap",
"typing.Generator",
"typing.AsyncGenerator",
"typing.Type",
"typing.Pattern",
"typing.Match",
)
)
CLASS_GETITEM_TEMPLATE = """
@classmethod
def __class_getitem__(cls, item):
return cls
"""
def looks_like_typing_typevar_or_newtype(node) -> bool:
func = node.func
if isinstance(func, Attribute):
return func.attrname in TYPING_TYPEVARS
if isinstance(func, Name):
return func.name in TYPING_TYPEVARS
return False
def infer_typing_typevar_or_newtype(node, context_itton=None):
"""Infer a typing.TypeVar(...) or typing.NewType(...) call."""
try:
func = next(node.func.infer(context=context_itton))
except (InferenceError, StopIteration) as exc:
raise UseInferenceDefault from exc
if func.qname() not in TYPING_TYPEVARS_QUALIFIED:
raise UseInferenceDefault
if not node.args:
raise UseInferenceDefault
# Cannot infer from a dynamic class name (f-string)
if isinstance(node.args[0], JoinedStr):
raise UseInferenceDefault
typename = node.args[0].as_string().strip("'")
node = extract_node(TYPING_TYPE_TEMPLATE.format(typename))
return node.infer(context=context_itton)
def _looks_like_typing_subscript(node) -> bool:
"""Try to figure out if a Subscript node *might* be a typing-related subscript."""
if isinstance(node, Name):
return node.name in TYPING_MEMBERS
if isinstance(node, Attribute):
return node.attrname in TYPING_MEMBERS
if isinstance(node, Subscript):
return _looks_like_typing_subscript(node.value)
return False
def infer_typing_attr(
node: Subscript, ctx: context.InferenceContext | None = None
) -> Iterator[ClassDef]:
"""Infer a typing.X[...] subscript."""
try:
value = next(node.value.infer()) # type: ignore[union-attr] # value shouldn't be None for Subscript.
except (InferenceError, StopIteration) as exc:
raise UseInferenceDefault from exc
if not value.qname().startswith("typing.") or value.qname() in TYPING_ALIAS:
# If typing subscript belongs to an alias handle it separately.
raise UseInferenceDefault
if isinstance(value, ClassDef) and value.qname() in {
"typing.Generic",
"typing.Annotated",
"typing_extensions.Annotated",
}:
# typing.Generic and typing.Annotated (PY39) are subscriptable
# through __class_getitem__. Since astroid can't easily
# infer the native methods, replace them for an easy inference tip
func_to_add = _extract_single_node(CLASS_GETITEM_TEMPLATE)
value.locals["__class_getitem__"] = [func_to_add]
if (
isinstance(node.parent, ClassDef)
and node in node.parent.bases
and getattr(node.parent, "__cache", None)
):
# node.parent.slots is evaluated and cached before the inference tip
# is first applied. Remove the last result to allow a recalculation of slots
cache = node.parent.__cache # type: ignore[attr-defined] # Unrecognized getattr
if cache.get(node.parent.slots) is not None:
del cache[node.parent.slots]
return iter([value])
node = extract_node(TYPING_TYPE_TEMPLATE.format(value.qname().split(".")[-1]))
return node.infer(context=ctx)
def _looks_like_typedDict( # pylint: disable=invalid-name
node: FunctionDef | ClassDef,
) -> bool:
"""Check if node is TypedDict FunctionDef."""
return node.qname() in TYPING_TYPEDDICT_QUALIFIED
def infer_old_typedDict( # pylint: disable=invalid-name
node: ClassDef, ctx: context.InferenceContext | None = None
) -> Iterator[ClassDef]:
func_to_add = _extract_single_node("dict")
node.locals["__call__"] = [func_to_add]
return iter([node])
def infer_typedDict( # pylint: disable=invalid-name
node: FunctionDef, ctx: context.InferenceContext | None = None
) -> Iterator[ClassDef]:
"""Replace TypedDict FunctionDef with ClassDef."""
class_def = ClassDef(
name="TypedDict",
lineno=node.lineno,
col_offset=node.col_offset,
parent=node.parent,
)
class_def.postinit(bases=[extract_node("dict")], body=[], decorators=None)
func_to_add = _extract_single_node("dict")
class_def.locals["__call__"] = [func_to_add]
return iter([class_def])
def _looks_like_typing_alias(node: Call) -> bool:
"""
Returns True if the node corresponds to a call to _alias function.
For example :
MutableSet = _alias(collections.abc.MutableSet, T)
:param node: call node
"""
return (
isinstance(node.func, Name)
and node.func.name == "_alias"
and (
# _alias function works also for builtins object such as list and dict
isinstance(node.args[0], (Attribute, Name))
)
)
def _forbid_class_getitem_access(node: ClassDef) -> None:
"""Disable the access to __class_getitem__ method for the node in parameters."""
def full_raiser(origin_func, attr, *args, **kwargs):
"""
Raises an AttributeInferenceError in case of access to __class_getitem__ method.
Otherwise, just call origin_func.
"""
if attr == "__class_getitem__":
raise AttributeInferenceError("__class_getitem__ access is not allowed")
return origin_func(attr, *args, **kwargs)
try:
node.getattr("__class_getitem__")
# If we are here, then we are sure to modify an object that does have
# __class_getitem__ method (which origin is the protocol defined in
# collections module) whereas the typing module considers it should not.
# We do not want __class_getitem__ to be found in the classdef
partial_raiser = partial(full_raiser, node.getattr)
node.getattr = partial_raiser
except AttributeInferenceError:
pass
def infer_typing_alias(
node: Call, ctx: context.InferenceContext | None = None
) -> Iterator[ClassDef]:
"""
Infers the call to _alias function
Insert ClassDef, with same name as aliased class,
in mro to simulate _GenericAlias.
:param node: call node
:param context: inference context
"""
if (
not isinstance(node.parent, Assign)
or not len(node.parent.targets) == 1
or not isinstance(node.parent.targets[0], AssignName)
):
raise UseInferenceDefault
try:
res = next(node.args[0].infer(context=ctx))
except StopIteration as e:
raise InferenceError(node=node.args[0], context=ctx) from e
assign_name = node.parent.targets[0]
class_def = ClassDef(
name=assign_name.name,
lineno=assign_name.lineno,
col_offset=assign_name.col_offset,
parent=node.parent,
)
if isinstance(res, ClassDef):
# Only add `res` as base if it's a `ClassDef`
# This isn't the case for `typing.Pattern` and `typing.Match`
class_def.postinit(bases=[res], body=[], decorators=None)
maybe_type_var = node.args[1]
if (
not PY39_PLUS
and not (isinstance(maybe_type_var, Tuple) and not maybe_type_var.elts)
or PY39_PLUS
and isinstance(maybe_type_var, Const)
and maybe_type_var.value > 0
):
# If typing alias is subscriptable, add `__class_getitem__` to ClassDef
func_to_add = _extract_single_node(CLASS_GETITEM_TEMPLATE)
class_def.locals["__class_getitem__"] = [func_to_add]
else:
# If not, make sure that `__class_getitem__` access is forbidden.
# This is an issue in cases where the aliased class implements it,
# but the typing alias isn't subscriptable. E.g., `typing.ByteString` for PY39+
_forbid_class_getitem_access(class_def)
return iter([class_def])
def _looks_like_special_alias(node: Call) -> bool:
"""Return True if call is for Tuple or Callable alias.
In PY37 and PY38 the call is to '_VariadicGenericAlias' with 'tuple' as
first argument. In PY39+ it is replaced by a call to '_TupleType'.
PY37: Tuple = _VariadicGenericAlias(tuple, (), inst=False, special=True)
PY39: Tuple = _TupleType(tuple, -1, inst=False, name='Tuple')
PY37: Callable = _VariadicGenericAlias(collections.abc.Callable, (), special=True)
PY39: Callable = _CallableType(collections.abc.Callable, 2)
"""
return isinstance(node.func, Name) and (
not PY39_PLUS
and node.func.name == "_VariadicGenericAlias"
and (
isinstance(node.args[0], Name)
and node.args[0].name == "tuple"
or isinstance(node.args[0], Attribute)
and node.args[0].as_string() == "collections.abc.Callable"
)
or PY39_PLUS
and (
node.func.name == "_TupleType"
and isinstance(node.args[0], Name)
and node.args[0].name == "tuple"
or node.func.name == "_CallableType"
and isinstance(node.args[0], Attribute)
and node.args[0].as_string() == "collections.abc.Callable"
)
)
def infer_special_alias(
node: Call, ctx: context.InferenceContext | None = None
) -> Iterator[ClassDef]:
"""Infer call to tuple alias as new subscriptable class typing.Tuple."""
if not (
isinstance(node.parent, Assign)
and len(node.parent.targets) == 1
and isinstance(node.parent.targets[0], AssignName)
):
raise UseInferenceDefault
try:
res = next(node.args[0].infer(context=ctx))
except StopIteration as e:
raise InferenceError(node=node.args[0], context=ctx) from e
assign_name = node.parent.targets[0]
class_def = ClassDef(
name=assign_name.name,
parent=node.parent,
)
class_def.postinit(bases=[res], body=[], decorators=None)
func_to_add = _extract_single_node(CLASS_GETITEM_TEMPLATE)
class_def.locals["__class_getitem__"] = [func_to_add]
return iter([class_def])
def _looks_like_typing_cast(node: Call) -> bool:
return isinstance(node, Call) and (
isinstance(node.func, Name)
and node.func.name == "cast"
or isinstance(node.func, Attribute)
and node.func.attrname == "cast"
)
def infer_typing_cast(
node: Call, ctx: context.InferenceContext | None = None
) -> Iterator[NodeNG]:
"""Infer call to cast() returning same type as casted-from var."""
if not isinstance(node.func, (Name, Attribute)):
raise UseInferenceDefault
try:
func = next(node.func.infer(context=ctx))
except (InferenceError, StopIteration) as exc:
raise UseInferenceDefault from exc
if (
not isinstance(func, FunctionDef)
or func.qname() != "typing.cast"
or len(node.args) != 2
):
raise UseInferenceDefault
return node.args[1].infer(context=ctx)
AstroidManager().register_transform(
Call,
inference_tip(infer_typing_typevar_or_newtype),
looks_like_typing_typevar_or_newtype,
)
AstroidManager().register_transform(
Subscript, inference_tip(infer_typing_attr), _looks_like_typing_subscript
)
AstroidManager().register_transform(
Call, inference_tip(infer_typing_cast), _looks_like_typing_cast
)
if PY39_PLUS:
AstroidManager().register_transform(
FunctionDef, inference_tip(infer_typedDict), _looks_like_typedDict
)
elif PY38_PLUS:
AstroidManager().register_transform(
ClassDef, inference_tip(infer_old_typedDict), _looks_like_typedDict
)
AstroidManager().register_transform(
Call, inference_tip(infer_typing_alias), _looks_like_typing_alias
)
AstroidManager().register_transform(
Call, inference_tip(infer_special_alias), _looks_like_special_alias
)
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