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# Copyright (c) 2015-2018 Claudiu Popa <pcmanticore@gmail.com>
# Copyright (c) 2015-2016 Ceridwen <ceridwenv@gmail.com>
# Copyright (c) 2018 Bryce Guinta <bryce.paul.guinta@gmail.com>
# Licensed under the LGPL: https://www.gnu.org/licenses/old-licenses/lgpl-2.1.en.html
# For details: https://github.com/PyCQA/astroid/blob/master/COPYING.LESSER
"""
Various helper utilities.
"""
import builtins as builtins_mod
from astroid import bases
from astroid import context as contextmod
from astroid import exceptions
from astroid import manager
from astroid import nodes
from astroid import raw_building
from astroid import scoped_nodes
from astroid import util
BUILTINS = builtins_mod.__name__
def _build_proxy_class(cls_name, builtins):
proxy = raw_building.build_class(cls_name)
proxy.parent = builtins
return proxy
def _function_type(function, builtins):
if isinstance(function, scoped_nodes.Lambda):
if function.root().name == BUILTINS:
cls_name = "builtin_function_or_method"
else:
cls_name = "function"
elif isinstance(function, bases.BoundMethod):
cls_name = "method"
elif isinstance(function, bases.UnboundMethod):
cls_name = "function"
return _build_proxy_class(cls_name, builtins)
def _object_type(node, context=None):
astroid_manager = manager.AstroidManager()
builtins = astroid_manager.builtins_module
context = context or contextmod.InferenceContext()
for inferred in node.infer(context=context):
if isinstance(inferred, scoped_nodes.ClassDef):
if inferred.newstyle:
metaclass = inferred.metaclass()
if metaclass:
yield metaclass
continue
yield builtins.getattr("type")[0]
elif isinstance(inferred, (scoped_nodes.Lambda, bases.UnboundMethod)):
yield _function_type(inferred, builtins)
elif isinstance(inferred, scoped_nodes.Module):
yield _build_proxy_class("module", builtins)
else:
yield inferred._proxied
def object_type(node, context=None):
"""Obtain the type of the given node
This is used to implement the ``type`` builtin, which means that it's
used for inferring type calls, as well as used in a couple of other places
in the inference.
The node will be inferred first, so this function can support all
sorts of objects, as long as they support inference.
"""
try:
types = set(_object_type(node, context))
except exceptions.InferenceError:
return util.Uninferable
if len(types) > 1 or not types:
return util.Uninferable
return list(types)[0]
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_isinstance(node, class_or_seq, context=None):
"""Check if a node 'isinstance' any node in class_or_seq
:param node: A given node
:param class_or_seq: Union[nodes.NodeNG, Sequence[nodes.NodeNG]]
:rtype: bool
:raises AstroidTypeError: if the given ``classes_or_seq`` are not types
"""
obj_type = object_type(node, context)
if obj_type is util.Uninferable:
return util.Uninferable
return _object_type_is_subclass(obj_type, class_or_seq, context=context)
def object_issubclass(node, class_or_seq, context=None):
"""Check if a type is a subclass of any node in class_or_seq
:param node: A given node
:param class_or_seq: Union[Nodes.NodeNG, Sequence[nodes.NodeNG]]
:rtype: bool
:raises AstroidTypeError: if the given ``classes_or_seq`` are not types
:raises AstroidError: if the type of the given node cannot be inferred
or its type's mro doesn't work
"""
if not isinstance(node, nodes.ClassDef):
raise TypeError("{node} needs to be a ClassDef node".format(node=node))
return _object_type_is_subclass(node, class_or_seq, context=context)
def safe_infer(node, context=None):
"""Return the inferred value for the given node.
Return None if inference failed or if there is some ambiguity (more than
one node has been inferred).
"""
try:
inferit = node.infer(context=context)
value = next(inferit)
except exceptions.InferenceError:
return None
try:
next(inferit)
return None # None if there is ambiguity on the inferred node
except exceptions.InferenceError:
return None # there is some kind of ambiguity
except StopIteration:
return value
def has_known_bases(klass, context=None):
"""Return true if all base classes of a class could be inferred."""
try:
return klass._all_bases_known
except AttributeError:
pass
for base in klass.bases:
result = safe_infer(base, context=context)
# TODO: check for A->B->A->B pattern in class structure too?
if (
not isinstance(result, scoped_nodes.ClassDef)
or result is klass
or not has_known_bases(result, context=context)
):
klass._all_bases_known = False
return False
klass._all_bases_known = True
return True
def _type_check(type1, type2):
if not all(map(has_known_bases, (type1, type2))):
raise exceptions._NonDeducibleTypeHierarchy
if not all([type1.newstyle, type2.newstyle]):
return False
try:
return type1 in type2.mro()[:-1]
except exceptions.MroError:
# The MRO is invalid.
raise exceptions._NonDeducibleTypeHierarchy
def is_subtype(type1, type2):
"""Check if *type1* is a subtype of *typ2*."""
return _type_check(type2, type1)
def is_supertype(type1, type2):
"""Check if *type2* is a supertype of *type1*."""
return _type_check(type1, type2)
def class_instance_as_index(node):
"""Get the value as an index for the given instance.
If an instance provides an __index__ method, then it can
be used in some scenarios where an integer is expected,
for instance when multiplying or subscripting a list.
"""
context = contextmod.InferenceContext()
context.callcontext = contextmod.CallContext(args=[node])
try:
for inferred in node.igetattr("__index__", context=context):
if not isinstance(inferred, bases.BoundMethod):
continue
for result in inferred.infer_call_result(node, context=context):
if isinstance(result, nodes.Const) and isinstance(result.value, int):
return result
except exceptions.InferenceError:
pass
return None
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())
)
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
raise exceptions.AstroidTypeError(
"'{}' object cannot be interpreted as an integer".format(result_of_len)
)