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# Licensed under the LGPL: https://www.gnu.org/licenses/old-licenses/lgpl-2.1.en.html
# For details: https://github.com/PyCQA/astroid/blob/main/LICENSE
# Copyright (c) https://github.com/PyCQA/astroid/blob/main/CONTRIBUTORS.txt
"""Various helper utilities."""
from __future__ import annotations
from collections.abc import Generator
from astroid import bases, manager, nodes, objects, raw_building, util
from astroid.context import CallContext, InferenceContext
from astroid.exceptions import (
AstroidTypeError,
AttributeInferenceError,
InferenceError,
MroError,
_NonDeducibleTypeHierarchy,
)
from astroid.nodes import scoped_nodes
from astroid.typing import InferenceResult, SuccessfulInferenceResult
def _build_proxy_class(cls_name: str, builtins: nodes.Module) -> nodes.ClassDef:
proxy = raw_building.build_class(cls_name)
proxy.parent = builtins
return proxy
def _function_type(
function: nodes.Lambda | bases.UnboundMethod, builtins: nodes.Module
) -> nodes.ClassDef:
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"
else:
cls_name = "function"
return _build_proxy_class(cls_name, builtins)
def _object_type(
node: SuccessfulInferenceResult, context: InferenceContext | None = None
) -> Generator[InferenceResult | None, None, None]:
astroid_manager = manager.AstroidManager()
builtins = astroid_manager.builtins_module
context = context or InferenceContext()
for inferred in node.infer(context=context):
if isinstance(inferred, scoped_nodes.ClassDef):
if inferred.newstyle:
metaclass = inferred.metaclass(context=context)
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)
elif isinstance(inferred, nodes.Unknown):
raise InferenceError
elif isinstance(inferred, util.UninferableBase):
yield inferred
elif isinstance(inferred, (bases.Proxy, nodes.Slice, objects.Super)):
yield inferred._proxied
else: # pragma: no cover
raise AssertionError(f"We don't handle {type(inferred)} currently")
def object_type(
node: SuccessfulInferenceResult, context: InferenceContext | None = None
) -> InferenceResult | 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 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: InferenceContext | None = None
):
if not isinstance(class_or_seq, (tuple, list)):
class_seq = (class_or_seq,)
else:
class_seq = class_or_seq
if isinstance(obj_type, util.UninferableBase):
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 isinstance(klass, util.UninferableBase):
raise 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: InferenceContext | None = 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 isinstance(obj_type, util.UninferableBase):
return util.Uninferable
return _object_type_is_subclass(obj_type, class_or_seq, context=context)
def object_issubclass(node, class_or_seq, context: InferenceContext | None = 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(f"{node} needs to be a ClassDef node")
return _object_type_is_subclass(node, class_or_seq, context=context)
def safe_infer(
node: nodes.NodeNG | bases.Proxy, context: InferenceContext | None = None
) -> InferenceResult | 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 (InferenceError, StopIteration):
return None
try:
next(inferit)
return None # None if there is ambiguity on the inferred node
except InferenceError:
return None # there is some kind of ambiguity
except StopIteration:
return value
def has_known_bases(klass, context: InferenceContext | None = None) -> bool:
"""Return whether 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) -> bool:
if not all(map(has_known_bases, (type1, type2))):
raise _NonDeducibleTypeHierarchy
if not all([type1.newstyle, type2.newstyle]):
return False
try:
return type1 in type2.mro()[:-1]
except MroError as e:
# The MRO is invalid.
raise _NonDeducibleTypeHierarchy from e
def is_subtype(type1, type2) -> bool:
"""Check if *type1* is a subtype of *type2*."""
return _type_check(type1=type2, type2=type1)
def is_supertype(type1, type2) -> bool:
"""Check if *type2* is a supertype of *type1*."""
return _type_check(type1, type2)
def class_instance_as_index(node: SuccessfulInferenceResult) -> nodes.Const | None:
"""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 = InferenceContext()
try:
for inferred in node.igetattr("__index__", context=context):
if not isinstance(inferred, bases.BoundMethod):
continue
context.boundnode = node
context.callcontext = CallContext(args=[], callee=inferred)
for result in inferred.infer_call_result(node, context=context):
if isinstance(result, nodes.Const) and isinstance(result.value, int):
return result
except InferenceError:
pass
return None
def object_len(node, context: InferenceContext | None = 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(future=True)
if (
isinstance(node_frame, scoped_nodes.FunctionDef)
and node_frame.name == "__len__"
and hasattr(inferred_node, "_proxied")
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 InferenceError(message)
if inferred_node is None or isinstance(inferred_node, util.UninferableBase):
raise 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 InferenceError(node=node)
try:
len_call = next(node_type.igetattr("__len__", context=context))
except StopIteration as e:
raise AstroidTypeError(str(e)) from e
except AttributeInferenceError as e:
raise AstroidTypeError(
f"object of type '{node_type.pytype()}' has no len()"
) from e
inferred = len_call.infer_call_result(node, context)
if isinstance(inferred, util.UninferableBase):
raise InferenceError(node=node, context=context)
result_of_len = next(inferred, None)
if (
isinstance(result_of_len, nodes.Const)
and result_of_len.pytype() == "builtins.int"
):
return result_of_len.value
if (
result_of_len is None
or 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 AstroidTypeError(
f"'{result_of_len}' object cannot be interpreted as an integer"
)