def _infer_context_manager(self, mgr, context):
inferred = next(mgr.infer(context=context))
if isinstance(inferred, bases.Generator):
# Check if it is decorated with contextlib.contextmanager.
func = inferred.parent
if not func.decorators:
raise exceptions.InferenceError(
"No decorators found on inferred generator %s", node=func
)
for decorator_node in func.decorators.nodes:
decorator = next(decorator_node.infer(context=context))
if isinstance(decorator, nodes.FunctionDef):
if decorator.qname() == _CONTEXTLIB_MGR:
break
else:
# It doesn't interest us.
raise exceptions.InferenceError(node=func)
# Get the first yield point. If it has multiple yields,
# then a RuntimeError will be raised.
possible_yield_points = func.nodes_of_class(nodes.Yield)
# Ignore yields in nested functions
yield_point = next(
(node for node in possible_yield_points if node.scope() == func), None
)
if yield_point:
if not yield_point.value:
const = nodes.Const(None)
const.parent = yield_point
const.lineno = yield_point.lineno
yield const
else:
yield from yield_point.value.infer(context=context)
elif isinstance(inferred, bases.Instance):
try:
enter = next(inferred.igetattr("__enter__", context=context))
except (exceptions.InferenceError, exceptions.AttributeInferenceError):
raise exceptions.InferenceError(node=inferred)
if not isinstance(enter, bases.BoundMethod):
raise exceptions.InferenceError(node=enter)
yield from enter.infer_call_result(self, context)
else:
raise exceptions.InferenceError(node=mgr)
def _infer_context_manager(self, mgr, context):
try:
inferred = next(mgr.infer(context=context))
except exceptions.InferenceError:
return
if isinstance(inferred, bases.Generator):
# Check if it is decorated with contextlib.contextmanager.
func = inferred.parent
if not func.decorators:
return
for decorator_node in func.decorators.nodes:
decorator = next(decorator_node.infer(context))
if isinstance(decorator, nodes.FunctionDef):
if decorator.qname() == _CONTEXTLIB_MGR:
break
else:
# It doesn't interest us.
return
# Get the first yield point. If it has multiple yields,
# then a RuntimeError will be raised.
# TODO(cpopa): Handle flows.
yield_point = next(func.nodes_of_class(nodes.Yield), None)
if yield_point:
if not yield_point.value:
# TODO(cpopa): an empty yield. Should be wrapped to Const.
const = nodes.Const(None)
const.parent = yield_point
const.lineno = yield_point.lineno
yield const
else:
for inferred in yield_point.value.infer(context=context):
yield inferred
elif isinstance(inferred, bases.Instance):
try:
enter = next(inferred.igetattr('__enter__', context=context))
except (exceptions.InferenceError, exceptions.AttributeInferenceError):
return
if not isinstance(enter, bases.BoundMethod):
return
if not context.callcontext:
context.callcontext = contextmod.CallContext(args=[inferred])
for result in enter.infer_call_result(self, context):
yield result
def infer_issubclass(callnode, context=None):
"""Infer issubclass() calls
:param nodes.Call callnode: an `issubclass` call
:param InferenceContext: 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 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 const_infer_binary_op(self, opnode, operator, other, context, _):
not_implemented = nodes.Const(NotImplemented)
if isinstance(other, nodes.Const):
try:
impl = BIN_OP_IMPL[operator]
try:
yield nodes.const_factory(impl(self.value, other.value))
except TypeError:
# ArithmeticError is not enough: float >> float is a TypeError
yield not_implemented
except Exception: # pylint: disable=broad-except
yield util.Uninferable
except TypeError:
yield not_implemented
elif isinstance(self.value, six.string_types) and operator == '%':
# TODO(cpopa): implement string interpolation later on.
yield util.Uninferable
else:
yield not_implemented
def instance_getitem(self, index, context=None):
# Rewrap index to Const for this case
index = nodes.Const(index)
if context:
new_context = context.clone()
else:
context = new_context = contextmod.InferenceContext()
# Create a new callcontext for providing index as an argument.
new_context.callcontext = contextmod.CallContext(args=[index])
new_context.boundnode = self
method = next(self.igetattr('__getitem__', context=context))
if not isinstance(method, bases.BoundMethod):
raise exceptions.InferenceError
try:
return next(method.infer_call_result(self, new_context))
except StopIteration:
raise exceptions.InferenceError
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_callable(node, context=None):
"""Understand callable calls
This follows Python's semantics, where an object
is callable if it provides an attribute __call__,
even though that attribute is something which can't be
called.
"""
if len(node.args) != 1:
# Invalid callable call.
raise UseInferenceDefault
argument = node.args[0]
try:
inferred = next(argument.infer(context=context))
except InferenceError:
return util.Uninferable
if inferred is util.Uninferable:
return util.Uninferable
return nodes.Const(inferred.callable())
def visit_name(self, node, parent, assign_ctx=None):
"""visit a Name node by returning a fresh instance of it"""
# True and False can be assigned to something in py2x, so we have to
# check first the asscontext
# pylint: disable=redefined-variable-type
if assign_ctx == "Del":
newnode = new.DelName()
elif assign_ctx is not None: # Ass
newnode = new.AssName()
elif node.id in CONST_NAME_TRANSFORMS:
newnode = new.Const(CONST_NAME_TRANSFORMS[node.id])
_set_infos(node, newnode, parent)
return newnode
else:
newnode = new.Name()
_lineno_parent(node, newnode, parent)
newnode.name = node.id
# XXX REMOVE me :
if assign_ctx in ('Del', 'Assign'): # 'Aug' ??
self._save_assignment(newnode)
return newnode
def visit_name(self, node, parent):
"""visit a Name node by returning a fresh instance of it"""
# True and False can be assigned to something in py2x, so we have to
# check first the asscontext
if self.asscontext == "Del":
newnode = new.DelName()
elif self.asscontext is not None: # Ass
assert self.asscontext == "Ass"
newnode = new.AssName()
elif node.id in CONST_NAME_TRANSFORMS:
newnode = new.Const(CONST_NAME_TRANSFORMS[node.id])
_set_infos(node, newnode, parent)
return newnode
else:
newnode = new.Name()
_lineno_parent(node, newnode, parent)
newnode.name = node.id
# XXX REMOVE me :
if self.asscontext in ('Del', 'Ass'): # 'Aug' ??
self._save_assignment(newnode)
return newnode
def tl_infer_binary_op(
self,
opnode: nodes.BinOp,
operator: str,
other: nodes.NodeNG,
context: InferenceContext,
method: nodes.FunctionDef,
) -> Generator[nodes.NodeNG | type[util.Uninferable], None, None]:
"""Infer a binary operation on a tuple or list.
The instance on which the binary operation is performed is a tuple
or list. This refers to the left-hand side of the operation, so:
'tuple() + 1' or '[] + A()'
"""
# For tuples and list the boundnode is no longer the tuple or list instance
context.boundnode = None
not_implemented = nodes.Const(NotImplemented)
if isinstance(other, self.__class__) and operator == "+":
node = self.__class__(parent=opnode)
node.elts = list(
itertools.chain(
_filter_uninferable_nodes(self.elts, context),
_filter_uninferable_nodes(other.elts, context),
))
yield node
elif isinstance(other, nodes.Const) and operator == "*":
if not isinstance(other.value, int):
yield not_implemented
return
yield _multiply_seq_by_int(self, opnode, other, context)
elif isinstance(other, bases.Instance) and operator == "*":
# Verify if the instance supports __index__.
as_index = helpers.class_instance_as_index(other)
if not as_index:
yield util.Uninferable
else:
yield _multiply_seq_by_int(self, opnode, as_index, context)
else:
yield not_implemented
def infer_isinstance(callnode, context=None):
"""Infer isinstance calls
:param nodes.Call callnode: an isinstance call
:param InferenceContext: 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 _resolve_asspart(parts, asspath, context):
"""recursive function to resolve multiple assignments"""
asspath = asspath[:]
index = asspath.pop(0)
for part in parts:
assigned = None
if isinstance(part, nodes.Dict):
# A dictionary in an iterating context
try:
assigned, _ = part.items[index]
except IndexError:
return
elif hasattr(part, 'getitem'):
index_node = nodes.Const(index)
try:
assigned = part.getitem(index_node, context)
# XXX raise a specific exception to avoid potential hiding of
# unexpected exception ?
except (exceptions.AstroidTypeError, exceptions.AstroidIndexError):
return
if not assigned:
return
if not asspath:
# we achieved to resolved the assignment path, don't infer the
# last part
yield assigned
elif assigned is util.Uninferable:
return
else:
# we are not yet on the last part of the path search on each
# possibly inferred value
try:
yield from _resolve_asspart(assigned.infer(context), asspath,
context)
except exceptions.InferenceError:
return
def tl_infer_binary_op(self, opnode, operator, other, context, method):
not_implemented = nodes.Const(NotImplemented)
if isinstance(other, self.__class__) and operator == '+':
node = self.__class__(parent=opnode)
elts = list(_filter_uninferable_nodes(self.elts, context))
elts += list(_filter_uninferable_nodes(other.elts, context))
node.elts = elts
yield node
elif isinstance(other, nodes.Const) and operator == '*':
if not isinstance(other.value, int):
yield not_implemented
return
yield _multiply_seq_by_int(self, opnode, other, context)
elif isinstance(other, bases.Instance) and operator == '*':
# Verify if the instance supports __index__.
as_index = helpers.class_instance_as_index(other)
if not as_index:
yield util.Uninferable
else:
yield _multiply_seq_by_int(self, opnode, as_index, context)
else:
yield not_implemented
def visit_name(self, node, parent):
"""visit a Name node by returning a fresh instance of it"""
context = self._get_context(node)
# True and False can be assigned to something in py2x, so we have to
# check first the context.
if context == astroid.Del:
newnode = nodes.DelName(node.id, node.lineno, node.col_offset,
parent)
elif context == astroid.Store:
newnode = nodes.AssignName(node.id, node.lineno, node.col_offset,
parent)
elif node.id in CONST_NAME_TRANSFORMS:
newnode = nodes.Const(CONST_NAME_TRANSFORMS[node.id],
getattr(node, 'lineno', None),
getattr(node, 'col_offset', None), parent)
return newnode
else:
newnode = nodes.Name(node.id, node.lineno, node.col_offset, parent)
# XXX REMOVE me :
if context in (astroid.Del, astroid.Store): # 'Aug' ??
self._save_assignment(newnode)
return newnode
def _resolve_looppart(parts, assign_path, context):
"""recursive function to resolve multiple assignments on loops"""
assign_path = assign_path[:]
index = assign_path.pop(0)
for part in parts:
if part is util.Uninferable:
continue
if not hasattr(part, "itered"):
continue
try:
itered = part.itered()
except TypeError:
continue
for stmt in itered:
index_node = nodes.Const(index)
try:
assigned = stmt.getitem(index_node, context)
except (
AttributeError,
exceptions.AstroidTypeError,
exceptions.AstroidIndexError,
):
continue
if not assign_path:
# we achieved to resolved the assignment path,
# don't infer the last part
yield assigned
elif assigned is util.Uninferable:
break
else:
# we are not yet on the last part of the path
# search on each possibly inferred value
try:
yield from _resolve_looppart(
assigned.infer(context), assign_path, context
)
except exceptions.InferenceError:
break
def test_cls_special_attributes_1(self):
cls = MODULE['YO']
self.assertEqual(len(cls.getattr('__bases__')), 1)
self.assertEqual(len(cls.getattr('__name__')), 1)
self.assertIsInstance(cls.getattr('__name__')[0], nodes.Const)
self.assertEqual(cls.getattr('__name__')[0].value, 'YO')
self.assertEqual(len(cls.getattr('__doc__')), 1)
self.assertIsInstance(cls.getattr('__doc__')[0], nodes.Const)
self.assertEqual(cls.getattr('__doc__')[0].value, 'hehe')
self.assertEqual(len(cls.getattr('__module__')), 1)
self.assertIsInstance(cls.getattr('__module__')[0], nodes.Const)
self.assertEqual(cls.getattr('__module__')[0].value, 'data.module')
self.assertEqual(len(cls.getattr('__dict__')), 1)
if not cls.newstyle:
self.assertRaises(NotFoundError, cls.getattr, '__mro__')
for cls in (nodes.List._proxied, nodes.Const(1)._proxied):
self.assertEqual(len(cls.getattr('__bases__')), 1)
self.assertEqual(len(cls.getattr('__name__')), 1)
self.assertEqual(len(cls.getattr('__doc__')), 1, (cls, cls.getattr('__doc__')))
self.assertEqual(cls.getattr('__doc__')[0].value, cls.doc)
self.assertEqual(len(cls.getattr('__module__')), 1)
self.assertEqual(len(cls.getattr('__dict__')), 1)
self.assertEqual(len(cls.getattr('__mro__')), 1)
def _infer_compare(self: nodes.Compare,
context: Optional[InferenceContext] = None) -> Any:
"""Chained comparison inference logic."""
retval = True
ops = self.ops
left_node = self.left
lhs = list(left_node.infer(context=context))
# should we break early if first element is uninferable?
for op, right_node in ops:
# eagerly evaluate rhs so that values can be re-used as lhs
rhs = list(right_node.infer(context=context))
try:
retval = _do_compare(lhs, op, rhs)
except AstroidTypeError:
retval = util.Uninferable
break
if retval is not True:
break # short-circuit
lhs = rhs # continue
if retval is util.Uninferable:
yield retval
else:
yield nodes.Const(retval)
def test_copy(self):
"""
Make sure copying a Const object doesn't result in infinite recursion
"""
const = copy.copy(nodes.Const(1))
assert const.value == 1
def visit_nameconstant(self, node, parent):
# in Python 3.4 we have NameConstant for True / False / None
return nodes.Const(node.value, getattr(node, 'lineno', None),
getattr(node, 'col_offset', None), parent)
def visit_num(self, node, parent):
"""visit a Num node by returning a fresh instance of Const"""
return nodes.Const(node.n, getattr(node, 'lineno', None),
getattr(node, 'col_offset', None), parent)
def visit_str(self, node, parent):
"""visit a String/Bytes node by returning a fresh instance of Const"""
return nodes.Const(node.s, getattr(node, 'lineno', None),
getattr(node, 'col_offset', None), parent)
def visit_constant(self, node, parent):
"""visit a Constant node by returning a fresh instance of Const"""
return nodes.Const(node.value, getattr(node, 'lineno', None),
getattr(node, 'col_offset', None), parent)
def infer_dict_fromkeys(node, context=None):
"""Infer dict.fromkeys
:param nodes.Call node: dict.fromkeys() call to infer
:param context.InferenceContext: 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:
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)
elif 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)
elif 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([])
def test_unpacking_in_dict_getitem(self):
node = extract_node('{1:2, **{2:3, 3:4}, **{5: 6}}')
for key, expected in ((1, 2), (2, 3), (3, 4), (5, 6)):
value = node.getitem(nodes.Const(key))
self.assertIsInstance(value, nodes.Const)
self.assertEqual(value.value, expected)
def test_genexpr(node):
if node.elt.value == 1:
node.elt = nodes.Const(2, node.lineno, node.col_offset,
node.parent)
return node
return None
def visit_num(self, node, parent):
"""visit a Num node by returning a fresh instance of Const"""
newnode = new.Const(node.n)
_set_infos(node, newnode, parent)
return newnode
def visit_nameconstant(self, node, parent):
# in Python 3.4 we have NameConstant for True / False / None
newnode = new.Const(node.value)
_set_infos(node, newnode, parent)
return newnode
def _patch_uuid_class(node):
# The .int member is patched using __dict__
node.locals["int"] = [nodes.Const(0, parent=node)]
def visit_str(self, node, parent):
"""visit a Str node by returning a fresh instance of Const"""
newnode = new.Const(node.s)
_set_infos(node, newnode, parent)
return newnode
def _check_new_format_specifiers(self, node, fields, named):
"""
Check attribute and index access in the format
string ("{0.a}" and "{0[a]}").
"""
for key, specifiers in fields:
# Obtain the argument. If it can't be obtained
# or inferred, skip this check.
if key == "":
# {[0]} will have an unnamed argument, defaulting
# to 0. It will not be present in `named`, so use the value
# 0 for it.
key = 0
if isinstance(key, numbers.Number):
try:
argname = utils.get_argument_from_call(node, key)
except utils.NoSuchArgumentError:
continue
else:
if key not in named:
continue
argname = named[key]
if argname in (astroid.Uninferable, None):
continue
try:
argument = utils.safe_infer(argname)
except astroid.InferenceError:
continue
if not specifiers or not argument:
# No need to check this key if it doesn't
# use attribute / item access
continue
if argument.parent and isinstance(argument.parent,
nodes.Arguments):
# Ignore any object coming from an argument,
# because we can't infer its value properly.
continue
previous = argument
parsed = []
for is_attribute, specifier in specifiers:
if previous is astroid.Uninferable:
break
parsed.append((is_attribute, specifier))
if is_attribute:
try:
previous = previous.getattr(specifier)[0]
except astroid.NotFoundError:
if (hasattr(previous, "has_dynamic_getattr")
and previous.has_dynamic_getattr()):
# Don't warn if the object has a custom __getattr__
break
path = get_access_path(key, parsed)
self.add_message(
"missing-format-attribute",
args=(specifier, path),
node=node,
)
break
else:
warn_error = False
if hasattr(previous, "getitem"):
try:
previous = previous.getitem(nodes.Const(specifier))
except (
astroid.AstroidIndexError,
astroid.AstroidTypeError,
astroid.AttributeInferenceError,
):
warn_error = True
except astroid.InferenceError:
break
if previous is astroid.Uninferable:
break
else:
try:
# Lookup __getitem__ in the current node,
# but skip further checks, because we can't
# retrieve the looked object
previous.getattr("__getitem__")
break
except astroid.NotFoundError:
warn_error = True
if warn_error:
path = get_access_path(key, parsed)
self.add_message("invalid-format-index",
args=(specifier, path),
node=node)
break
try:
previous = next(previous.infer())
except astroid.InferenceError:
# can't check further if we can't infer it
break
