def object_len(node, context=None):
"""Infer length of given node object
:param Union[nodes.ClassDef, nodes.Instance] node:
:param node: Node to infer length of
:raises AstroidTypeError: If an invalid node is returned
from __len__ method or no __len__ method exists
:raises InferenceError: If the given node cannot be inferred
or if multiple nodes are inferred
:rtype int: Integer length of node
"""
# pylint: disable=import-outside-toplevel; circular import
from astroid.objects import FrozenSet
inferred_node = safe_infer(node, context=context)
if inferred_node is None or inferred_node is util.Uninferable:
raise exceptions.InferenceError(node=node)
if isinstance(inferred_node, nodes.Const) and isinstance(
inferred_node.value, (bytes, str)):
return len(inferred_node.value)
if isinstance(inferred_node,
(nodes.List, nodes.Set, nodes.Tuple, FrozenSet)):
return len(inferred_node.elts)
if isinstance(inferred_node, nodes.Dict):
return len(inferred_node.items)
node_type = object_type(inferred_node, context=context)
if not node_type:
raise exceptions.InferenceError(node=node)
try:
len_call = next(node_type.igetattr("__len__", context=context))
except exceptions.AttributeInferenceError:
raise exceptions.AstroidTypeError(
"object of type '{}' has no len()".format(node_type.pytype()))
result_of_len = next(len_call.infer_call_result(node, context))
if (isinstance(result_of_len, nodes.Const)
and result_of_len.pytype() == "builtins.int"):
return result_of_len.value
if isinstance(
result_of_len,
bases.Instance) and result_of_len.is_subtype_of("builtins.int"):
# Fake a result as we don't know the arguments of the instance call.
return 0
raise exceptions.AstroidTypeError(
"'{}' object cannot be interpreted as an integer".format(
result_of_len))
def _object_type_is_subclass(obj_type, class_or_seq, context=None):
if not isinstance(class_or_seq, (tuple, list)):
class_seq = (class_or_seq, )
else:
class_seq = class_or_seq
if obj_type is util.Uninferable:
return util.Uninferable
# Instances are not types
class_seq = [
item if not isinstance(item, bases.Instance) else util.Uninferable
for item in class_seq
]
# strict compatibility with issubclass
# issubclass(type, (object, 1)) evaluates to true
# issubclass(object, (1, type)) raises TypeError
for klass in class_seq:
if klass is util.Uninferable:
raise exceptions.AstroidTypeError(
"arg 2 must be a type or tuple of types")
for obj_subclass in obj_type.mro():
if obj_subclass == klass:
return True
return False
def object_len(node, context=None):
"""Infer length of given node object
:param Union[nodes.ClassDef, nodes.Instance] node:
:param node: Node to infer length of
:raises AstroidTypeError: If an invalid node is returned
from __len__ method or no __len__ method exists
:raises InferenceError: If the given node cannot be inferred
or if multiple nodes are inferred
:rtype int: Integer length of node
"""
from astroid.objects import FrozenSet
inferred_node = safe_infer(node, context=context)
if inferred_node is None or inferred_node is util.Uninferable:
raise exceptions.InferenceError(node=node)
if (isinstance(inferred_node, nodes.Const)
and isinstance(inferred_node.value, (bytes, str))):
return len(inferred_node.value)
if isinstance(inferred_node,
(nodes.List, nodes.Set, nodes.Tuple, FrozenSet)):
return len(inferred_node.elts)
if isinstance(inferred_node, nodes.Dict):
return len(inferred_node.items)
try:
node_type = object_type(inferred_node, context=context)
len_call = next(node_type.igetattr("__len__", context=context))
except exceptions.AttributeInferenceError:
raise exceptions.AstroidTypeError(
"object of type '{}' has no len()".format(len_call.pytype()))
try:
result_of_len = next(len_call.infer_call_result(node, context))
# Remove StopIteration catch when #507 is fixed
except StopIteration:
raise exceptions.InferenceError(node=node)
if (isinstance(result_of_len, nodes.Const)
and result_of_len.pytype() == "builtins.int"):
return result_of_len.value
else:
raise exceptions.AstroidTypeError(
"'{}' object cannot be interpreted as an integer".format(
result_of_len))
def object_len(node, context=None):
"""Infer length of given node object
:param Union[nodes.ClassDef, nodes.Instance] node:
:param node: Node to infer length of
:raises AstroidTypeError: If an invalid node is returned
from __len__ method or no __len__ method exists
:raises InferenceError: If the given node cannot be inferred
or if multiple nodes are inferred or if the code executed in python
would result in a infinite recursive check for length
:rtype int: Integer length of node
"""
# pylint: disable=import-outside-toplevel; circular import
from astroid.objects import FrozenSet
inferred_node = safe_infer(node, context=context)
# prevent self referential length calls from causing a recursion error
# see https://github.com/PyCQA/astroid/issues/777
node_frame = node.frame()
if (isinstance(node_frame, scoped_nodes.FunctionDef)
and node_frame.name == "__len__" and inferred_node is not None
and inferred_node._proxied == node_frame.parent):
message = ("Self referential __len__ function will "
"cause a RecursionError on line {} of {}".format(
node.lineno,
node.root().file))
raise exceptions.InferenceError(message)
if inferred_node is None or inferred_node is util.Uninferable:
raise exceptions.InferenceError(node=node)
if isinstance(inferred_node, nodes.Const) and isinstance(
inferred_node.value, (bytes, str)):
return len(inferred_node.value)
if isinstance(inferred_node,
(nodes.List, nodes.Set, nodes.Tuple, FrozenSet)):
return len(inferred_node.elts)
if isinstance(inferred_node, nodes.Dict):
return len(inferred_node.items)
node_type = object_type(inferred_node, context=context)
if not node_type:
raise exceptions.InferenceError(node=node)
try:
len_call = next(node_type.igetattr("__len__", context=context))
except exceptions.AttributeInferenceError as e:
raise exceptions.AstroidTypeError(
"object of type '{}' has no len()".format(
node_type.pytype())) from e
result_of_len = next(len_call.infer_call_result(node, context))
if (isinstance(result_of_len, nodes.Const)
and result_of_len.pytype() == "builtins.int"):
return result_of_len.value
if isinstance(
result_of_len,
bases.Instance) and result_of_len.is_subtype_of("builtins.int"):
# Fake a result as we don't know the arguments of the instance call.
return 0
raise exceptions.AstroidTypeError(
"'{}' object cannot be interpreted as an integer".format(
result_of_len))
