def _get_elts(arg, context):
def is_iterable(n):
return isinstance(n, (nodes.List, nodes.Tuple, nodes.Set))
try:
inferred = next(arg.infer(context))
except (InferenceError, StopIteration) as exc:
raise UseInferenceDefault from exc
if isinstance(inferred, nodes.Dict):
items = inferred.items
elif is_iterable(inferred):
items = []
for elt in inferred.elts:
# If an item is not a pair of two items,
# then fallback to the default inference.
# Also, take in consideration only hashable items,
# tuples and consts. We are choosing Names as well.
if not is_iterable(elt):
raise UseInferenceDefault()
if len(elt.elts) != 2:
raise UseInferenceDefault()
if not isinstance(elt.elts[0],
(nodes.Tuple, nodes.Const, nodes.Name)):
raise UseInferenceDefault()
items.append(tuple(elt.elts))
else:
raise UseInferenceDefault()
return items
def infer_int(node, context=None):
"""Infer int() calls
:param nodes.Call node: int() call to infer
:param context.InferenceContext: node context
:rtype nodes.Const: a Const containing the integer value of the int() call
"""
call = arguments.CallSite.from_call(node, context=context)
if call.keyword_arguments:
raise UseInferenceDefault(
"TypeError: int() must take no keyword arguments")
if call.positional_arguments:
try:
first_value = next(
call.positional_arguments[0].infer(context=context))
except (InferenceError, StopIteration) as exc:
raise UseInferenceDefault(str(exc)) from exc
if first_value is util.Uninferable:
raise UseInferenceDefault
if isinstance(first_value, nodes.Const) and isinstance(
first_value.value, (int, str)):
try:
actual_value = int(first_value.value)
except ValueError:
return nodes.Const(0)
return nodes.Const(actual_value)
return nodes.Const(0)
def infer_named_tuple(node, context=None):
"""Specific inference function for namedtuple Call node"""
tuple_base_name = nodes.Name(name="tuple", parent=node.root())
class_node, name, attributes = infer_func_form(
node, tuple_base_name, context=context
)
call_site = arguments.CallSite.from_call(node, context=context)
node = extract_node("import collections; collections.namedtuple")
try:
func = next(node.infer())
except StopIteration as e:
raise InferenceError(node=node) from e
try:
rename = next(call_site.infer_argument(func, "rename", context)).bool_value()
except (InferenceError, StopIteration):
rename = False
try:
attributes = _check_namedtuple_attributes(name, attributes, rename)
except AstroidTypeError as exc:
raise UseInferenceDefault("TypeError: " + str(exc)) from exc
except AstroidValueError as exc:
raise UseInferenceDefault("ValueError: " + str(exc)) from exc
replace_args = ", ".join(f"{arg}=None" for arg in attributes)
field_def = (
" {name} = property(lambda self: self[{index:d}], "
"doc='Alias for field number {index:d}')"
)
field_defs = "\n".join(
field_def.format(name=name, index=index)
for index, name in enumerate(attributes)
)
fake = AstroidBuilder(AstroidManager()).string_build(
f"""
class {name}(tuple):
__slots__ = ()
_fields = {attributes!r}
def _asdict(self):
return self.__dict__
@classmethod
def _make(cls, iterable, new=tuple.__new__, len=len):
return new(cls, iterable)
def _replace(self, {replace_args}):
return self
def __getnewargs__(self):
return tuple(self)
{field_defs}
"""
)
class_node.locals["_asdict"] = fake.body[0].locals["_asdict"]
class_node.locals["_make"] = fake.body[0].locals["_make"]
class_node.locals["_replace"] = fake.body[0].locals["_replace"]
class_node.locals["_fields"] = fake.body[0].locals["_fields"]
for attr in attributes:
class_node.locals[attr] = fake.body[0].locals[attr]
# we use UseInferenceDefault, we can't be a generator so return an iterator
return iter([class_node])
def _functools_partial_inference(
node: nodes.Call,
context: InferenceContext | None = None
) -> Iterator[objects.PartialFunction]:
call = arguments.CallSite.from_call(node, context=context)
number_of_positional = len(call.positional_arguments)
if number_of_positional < 1:
raise UseInferenceDefault(
"functools.partial takes at least one argument")
if number_of_positional == 1 and not call.keyword_arguments:
raise UseInferenceDefault(
"functools.partial needs at least to have some filled arguments")
partial_function = call.positional_arguments[0]
try:
inferred_wrapped_function = next(
partial_function.infer(context=context))
except (InferenceError, StopIteration) as exc:
raise UseInferenceDefault from exc
if inferred_wrapped_function is Uninferable:
raise UseInferenceDefault("Cannot infer the wrapped function")
if not isinstance(inferred_wrapped_function, FunctionDef):
raise UseInferenceDefault("The wrapped function is not a function")
# Determine if the passed keywords into the callsite are supported
# by the wrapped function.
if not inferred_wrapped_function.args:
function_parameters = []
else:
function_parameters = chain(
inferred_wrapped_function.args.args or (),
inferred_wrapped_function.args.posonlyargs or (),
inferred_wrapped_function.args.kwonlyargs or (),
)
parameter_names = {
param.name
for param in function_parameters if isinstance(param, AssignName)
}
if set(call.keyword_arguments) - parameter_names:
raise UseInferenceDefault(
"wrapped function received unknown parameters")
partial_function = objects.PartialFunction(
call,
name=inferred_wrapped_function.name,
lineno=inferred_wrapped_function.lineno,
col_offset=inferred_wrapped_function.col_offset,
parent=node.parent,
)
partial_function.postinit(
args=inferred_wrapped_function.args,
body=inferred_wrapped_function.body,
decorators=inferred_wrapped_function.decorators,
returns=inferred_wrapped_function.returns,
type_comment_returns=inferred_wrapped_function.type_comment_returns,
type_comment_args=inferred_wrapped_function.type_comment_args,
doc_node=inferred_wrapped_function.doc_node,
)
return iter((partial_function, ))
def infer_str(node, context=None):
"""Infer str() calls
:param nodes.Call node: str() call to infer
:param context.InferenceContext: node context
:rtype nodes.Const: a Const containing an empty string
"""
call = arguments.CallSite.from_call(node, context=context)
if call.keyword_arguments:
raise UseInferenceDefault("TypeError: str() must take no keyword arguments")
try:
return nodes.Const("")
except (AstroidTypeError, InferenceError) as exc:
raise UseInferenceDefault(str(exc)) from exc
def _container_generic_transform( # pylint: disable=inconsistent-return-statements
arg, context, klass, iterables, build_elts):
if isinstance(arg, klass):
return arg
if isinstance(arg, iterables):
if all(isinstance(elt, nodes.Const) for elt in arg.elts):
elts = [elt.value for elt in arg.elts]
else:
# TODO: Does not handle deduplication for sets.
elts = []
for element in arg.elts:
if not element:
continue
inferred = helpers.safe_infer(element, context=context)
if inferred:
evaluated_object = nodes.EvaluatedObject(original=element,
value=inferred)
elts.append(evaluated_object)
elif isinstance(arg, nodes.Dict):
# Dicts need to have consts as strings already.
if not all(isinstance(elt[0], nodes.Const) for elt in arg.items):
raise UseInferenceDefault()
elts = [item[0].value for item in arg.items]
elif isinstance(arg, nodes.Const) and isinstance(arg.value, (str, bytes)):
elts = arg.value
else:
return
return klass.from_elements(elts=build_elts(elts))
def _infer_first(node, context):
if node is util.Uninferable:
raise UseInferenceDefault
try:
value = next(node.infer(context=context))
except StopIteration as exc:
raise InferenceError from exc
if value is util.Uninferable:
raise UseInferenceDefault()
return value
def infer_issubclass(callnode, context=None):
"""Infer issubclass() calls
:param nodes.Call callnode: an `issubclass` call
:param InferenceContext context: the context for the inference
:rtype nodes.Const: Boolean Const value of the `issubclass` call
:raises UseInferenceDefault: If the node cannot be inferred
"""
call = arguments.CallSite.from_call(callnode, context=context)
if call.keyword_arguments:
# issubclass doesn't support keyword arguments
raise UseInferenceDefault("TypeError: issubclass() takes no keyword arguments")
if len(call.positional_arguments) != 2:
raise UseInferenceDefault(
"Expected two arguments, got {count}".format(
count=len(call.positional_arguments)
)
)
# The left hand argument is the obj to be checked
obj_node, class_or_tuple_node = call.positional_arguments
try:
obj_type = next(obj_node.infer(context=context))
except (InferenceError, StopIteration) as exc:
raise UseInferenceDefault from exc
if not isinstance(obj_type, nodes.ClassDef):
raise UseInferenceDefault("TypeError: arg 1 must be class")
# The right hand argument is the class(es) that the given
# object is to be checked against.
try:
class_container = _class_or_tuple_to_container(
class_or_tuple_node, context=context
)
except InferenceError as exc:
raise UseInferenceDefault from exc
try:
issubclass_bool = helpers.object_issubclass(obj_type, class_container, context)
except AstroidTypeError as exc:
raise UseInferenceDefault("TypeError: " + str(exc)) from exc
except MroError as exc:
raise UseInferenceDefault from exc
return nodes.Const(issubclass_bool)
def infer_len(node, context=None):
"""Infer length calls
:param nodes.Call node: len call to infer
:param context.InferenceContext: node context
:rtype nodes.Const: a Const node with the inferred length, if possible
"""
call = arguments.CallSite.from_call(node, context=context)
if call.keyword_arguments:
raise UseInferenceDefault(
"TypeError: len() must take no keyword arguments")
if len(call.positional_arguments) != 1:
raise UseInferenceDefault(
"TypeError: len() must take exactly one argument "
"({len}) given".format(len=len(call.positional_arguments)))
[argument_node] = call.positional_arguments
try:
return nodes.Const(helpers.object_len(argument_node, context=context))
except (AstroidTypeError, InferenceError) as exc:
raise UseInferenceDefault(str(exc)) from exc
def infer_isinstance(callnode, context=None):
"""Infer isinstance calls
:param nodes.Call callnode: an isinstance call
:param InferenceContext context: context for call
(currently unused but is a common interface for inference)
:rtype nodes.Const: Boolean Const value of isinstance call
:raises UseInferenceDefault: If the node cannot be inferred
"""
call = arguments.CallSite.from_call(callnode, context=context)
if call.keyword_arguments:
# isinstance doesn't support keyword arguments
raise UseInferenceDefault("TypeError: isinstance() takes no keyword arguments")
if len(call.positional_arguments) != 2:
raise UseInferenceDefault(
"Expected two arguments, got {count}".format(
count=len(call.positional_arguments)
)
)
# The left hand argument is the obj to be checked
obj_node, class_or_tuple_node = call.positional_arguments
# The right hand argument is the class(es) that the given
# obj is to be check is an instance of
try:
class_container = _class_or_tuple_to_container(
class_or_tuple_node, context=context
)
except InferenceError as exc:
raise UseInferenceDefault from exc
try:
isinstance_bool = helpers.object_isinstance(obj_node, class_container, context)
except AstroidTypeError as exc:
raise UseInferenceDefault("TypeError: " + str(exc)) from exc
except MroError as exc:
raise UseInferenceDefault from exc
if isinstance_bool is util.Uninferable:
raise UseInferenceDefault
return nodes.Const(isinstance_bool)
def _infer_copy_method(
node: nodes.Call,
context: InferenceContext | None = None) -> Iterator[nodes.NodeNG]:
assert isinstance(node.func, nodes.Attribute)
inferred_orig, inferred_copy = itertools.tee(
node.func.expr.infer(context=context))
if all(
isinstance(inferred_node, (nodes.Dict, nodes.List, nodes.Set,
objects.FrozenSet))
for inferred_node in inferred_orig):
return inferred_copy
raise UseInferenceDefault()
def infer_namespace(node, context=None):
callsite = arguments.CallSite.from_call(node, context=context)
if not callsite.keyword_arguments:
# Cannot make sense of it.
raise UseInferenceDefault()
class_node = nodes.ClassDef("Namespace", "docstring")
class_node.parent = node.parent
for attr in set(callsite.keyword_arguments):
fake_node = nodes.EmptyNode()
fake_node.parent = class_node
fake_node.attrname = attr
class_node.instance_attrs[attr] = [fake_node]
return iter((class_node.instantiate_class(),))
def _inference_tip_cached(func: InferFn, instance: None, args: typing.Any,
kwargs: typing.Any) -> Iterator[InferOptions]:
"""Cache decorator used for inference tips"""
node = args[0]
try:
result = _cache[func, node]
# If through recursion we end up trying to infer the same
# func + node we raise here.
if result is None:
raise UseInferenceDefault()
except KeyError:
_cache[func, node] = None
result = _cache[func, node] = list(func(*args, **kwargs))
assert result
return iter(result)
def _container_generic_inference(node, context, node_type, transform):
args = node.args
if not args:
return node_type()
if len(node.args) > 1:
raise UseInferenceDefault()
(arg, ) = args
transformed = transform(arg)
if not transformed:
try:
inferred = next(arg.infer(context=context))
except (InferenceError, StopIteration) as exc:
raise UseInferenceDefault from exc
if inferred is util.Uninferable:
raise UseInferenceDefault
transformed = transform(inferred)
if not transformed or transformed is util.Uninferable:
raise UseInferenceDefault
return transformed
def infer_dict(node, context=None):
"""Try to infer a dict call to a Dict node.
The function treats the following cases:
* dict()
* dict(mapping)
* dict(iterable)
* dict(iterable, **kwargs)
* dict(mapping, **kwargs)
* dict(**kwargs)
If a case can't be inferred, we'll fallback to default inference.
"""
call = arguments.CallSite.from_call(node, context=context)
if call.has_invalid_arguments() or call.has_invalid_keywords():
raise UseInferenceDefault
args = call.positional_arguments
kwargs = list(call.keyword_arguments.items())
if not args and not kwargs:
# dict()
return nodes.Dict()
if kwargs and not args:
# dict(a=1, b=2, c=4)
items = [(nodes.Const(key), value) for key, value in kwargs]
elif len(args) == 1 and kwargs:
# dict(some_iterable, b=2, c=4)
elts = _get_elts(args[0], context)
keys = [(nodes.Const(key), value) for key, value in kwargs]
items = elts + keys
elif len(args) == 1:
items = _get_elts(args[0], context)
else:
raise UseInferenceDefault()
value = nodes.Dict(col_offset=node.col_offset,
lineno=node.lineno,
parent=node.parent)
value.postinit(items)
return value
def infer_type_sub(node, context=None):
"""
Infer a type[...] subscript
:param node: node to infer
:type node: astroid.nodes.node_classes.NodeNG
:param context: inference context
:type context: astroid.context.InferenceContext
:return: the inferred node
:rtype: nodes.NodeNG
"""
node_scope, _ = node.scope().lookup("type")
if node_scope.qname() != "builtins":
raise UseInferenceDefault()
class_src = """
class type:
def __class_getitem__(cls, key):
return cls
"""
node = extract_node(class_src)
return node.infer(context=context)
def _find_func_form_arguments(node, context):
def _extract_namedtuple_arg_or_keyword( # pylint: disable=inconsistent-return-statements
position, key_name=None
):
if len(args) > position:
return _infer_first(args[position], context)
if key_name and key_name in found_keywords:
return _infer_first(found_keywords[key_name], context)
args = node.args
keywords = node.keywords
found_keywords = (
{keyword.arg: keyword.value for keyword in keywords} if keywords else {}
)
name = _extract_namedtuple_arg_or_keyword(position=0, key_name="typename")
names = _extract_namedtuple_arg_or_keyword(position=1, key_name="field_names")
if name and names:
return name.value, names
raise UseInferenceDefault()
def infer_dict_fromkeys(node, context=None):
"""Infer dict.fromkeys
:param nodes.Call node: dict.fromkeys() call to infer
:param context.InferenceContext context: node context
:rtype nodes.Dict:
a Dictionary containing the values that astroid was able to infer.
In case the inference failed for any reason, an empty dictionary
will be inferred instead.
"""
def _build_dict_with_elements(elements):
new_node = nodes.Dict(col_offset=node.col_offset,
lineno=node.lineno,
parent=node.parent)
new_node.postinit(elements)
return new_node
call = arguments.CallSite.from_call(node, context=context)
if call.keyword_arguments:
raise UseInferenceDefault(
"TypeError: int() must take no keyword arguments")
if len(call.positional_arguments) not in {1, 2}:
raise UseInferenceDefault(
"TypeError: Needs between 1 and 2 positional arguments")
default = nodes.Const(None)
values = call.positional_arguments[0]
try:
inferred_values = next(values.infer(context=context))
except (InferenceError, StopIteration):
return _build_dict_with_elements([])
if inferred_values is util.Uninferable:
return _build_dict_with_elements([])
# Limit to a couple of potential values, as this can become pretty complicated
accepted_iterable_elements = (nodes.Const, )
if isinstance(inferred_values, (nodes.List, nodes.Set, nodes.Tuple)):
elements = inferred_values.elts
for element in elements:
if not isinstance(element, accepted_iterable_elements):
# Fallback to an empty dict
return _build_dict_with_elements([])
elements_with_value = [(element, default) for element in elements]
return _build_dict_with_elements(elements_with_value)
if isinstance(inferred_values, nodes.Const) and isinstance(
inferred_values.value, (str, bytes)):
elements = [(nodes.Const(element), default)
for element in inferred_values.value]
return _build_dict_with_elements(elements)
if isinstance(inferred_values, nodes.Dict):
keys = inferred_values.itered()
for key in keys:
if not isinstance(key, accepted_iterable_elements):
# Fallback to an empty dict
return _build_dict_with_elements([])
elements_with_value = [(element, default) for element in keys]
return _build_dict_with_elements(elements_with_value)
# Fallback to an empty dictionary
return _build_dict_with_elements([])