def _infer_instance_from_annotation(node: NodeNG,
ctx: context.InferenceContext = None
) -> Generator:
"""Infer an instance corresponding to the type annotation represented by node.
Currently has limited support for the typing module.
"""
klass = None
try:
klass = next(node.infer(context=ctx))
except (InferenceError, StopIteration):
yield Uninferable
if not isinstance(klass, ClassDef):
yield Uninferable
elif klass.root().name in {
"typing",
"_collections_abc",
"",
}: # "" because of synthetic nodes in brain_typing.py
if klass.name in _INFERABLE_TYPING_TYPES:
yield klass.instantiate_class()
else:
yield Uninferable
else:
yield klass.instantiate_class()
def _looks_like_dataclass_decorator(
node: NodeNG,
decorator_names: FrozenSet[str] = DATACLASSES_DECORATORS) -> bool:
"""Return True if node looks like a dataclass decorator.
Uses inference to lookup the value of the node, and if that fails,
matches against specific names.
"""
if isinstance(node, Call): # decorator with arguments
node = node.func
try:
inferred = next(node.infer())
except (InferenceError, StopIteration):
inferred = Uninferable
if inferred is Uninferable:
if isinstance(node, Name):
return node.name in decorator_names
if isinstance(node, Attribute):
return node.attrname in decorator_names
return False
return (isinstance(inferred, FunctionDef)
and inferred.name in decorator_names
and inferred.root().name in DATACLASS_MODULES)
def _is_init_var(node: NodeNG) -> bool:
"""Return True if node is an InitVar, with or without subscripting."""
try:
inferred = next(node.infer())
except (InferenceError, StopIteration):
return False
return getattr(inferred, "name", "") == "InitVar"
def _is_class_var(node: NodeNG) -> bool:
"""Return True if node is a ClassVar, with or without subscripting."""
if PY39_PLUS:
try:
inferred = next(node.infer())
except (InferenceError, StopIteration):
return False
return getattr(inferred, "name", "") == "ClassVar"
# Before Python 3.9, inference returns typing._SpecialForm instead of ClassVar.
# Our backup is to inspect the node's structure.
return isinstance(node, Subscript) and (
isinstance(node.value, Name) and node.value.name == "ClassVar"
or isinstance(node.value, Attribute)
and node.value.attrname == "ClassVar")
def looks_like_numpy_member(member_name: str, node: NodeNG) -> bool:
"""
Returns True if the node is a member of numpy whose
name is member_name.
:param member_name: name of the member
:param node: node to test
:return: True if the node is a member of numpy
"""
if (isinstance(node, Attribute) and node.attrname == member_name
and isinstance(node.expr, Name) and _is_a_numpy_module(node.expr)):
return True
if (isinstance(node, Name) and node.name == member_name
and node.root().name.startswith("numpy")):
return True
return False