311 lines
10 KiB
Python
311 lines
10 KiB
Python
# Licensed under the LGPL: https://www.gnu.org/licenses/old-licenses/lgpl-2.1.en.html
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# For details: https://github.com/PyCQA/astroid/blob/main/LICENSE
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# Copyright (c) https://github.com/PyCQA/astroid/blob/main/CONTRIBUTORS.txt
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"""
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Various helper utilities.
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"""
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from __future__ import annotations
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from astroid import bases, manager, nodes, raw_building, util
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from astroid.context import CallContext, InferenceContext
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from astroid.exceptions import (
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AstroidTypeError,
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AttributeInferenceError,
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InferenceError,
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MroError,
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_NonDeducibleTypeHierarchy,
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)
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from astroid.nodes import scoped_nodes
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from astroid.typing import InferenceResult
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def _build_proxy_class(cls_name: str, builtins: nodes.Module) -> nodes.ClassDef:
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proxy = raw_building.build_class(cls_name)
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proxy.parent = builtins
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return proxy
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def _function_type(
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function: nodes.Lambda | bases.UnboundMethod, builtins: nodes.Module
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) -> nodes.ClassDef:
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if isinstance(function, scoped_nodes.Lambda):
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if function.root().name == "builtins":
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cls_name = "builtin_function_or_method"
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else:
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cls_name = "function"
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elif isinstance(function, bases.BoundMethod):
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cls_name = "method"
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else:
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cls_name = "function"
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return _build_proxy_class(cls_name, builtins)
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def _object_type(node, context=None):
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astroid_manager = manager.AstroidManager()
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builtins = astroid_manager.builtins_module
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context = context or InferenceContext()
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for inferred in node.infer(context=context):
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if isinstance(inferred, scoped_nodes.ClassDef):
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if inferred.newstyle:
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metaclass = inferred.metaclass(context=context)
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if metaclass:
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yield metaclass
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continue
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yield builtins.getattr("type")[0]
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elif isinstance(inferred, (scoped_nodes.Lambda, bases.UnboundMethod)):
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yield _function_type(inferred, builtins)
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elif isinstance(inferred, scoped_nodes.Module):
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yield _build_proxy_class("module", builtins)
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elif isinstance(inferred, nodes.Unknown):
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raise InferenceError
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else:
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yield inferred._proxied
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def object_type(node, context=None):
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"""Obtain the type of the given node
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This is used to implement the ``type`` builtin, which means that it's
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used for inferring type calls, as well as used in a couple of other places
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in the inference.
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The node will be inferred first, so this function can support all
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sorts of objects, as long as they support inference.
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"""
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try:
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types = set(_object_type(node, context))
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except InferenceError:
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return util.Uninferable
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if len(types) > 1 or not types:
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return util.Uninferable
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return list(types)[0]
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def _object_type_is_subclass(obj_type, class_or_seq, context=None):
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if not isinstance(class_or_seq, (tuple, list)):
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class_seq = (class_or_seq,)
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else:
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class_seq = class_or_seq
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if obj_type is util.Uninferable:
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return util.Uninferable
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# Instances are not types
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class_seq = [
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item if not isinstance(item, bases.Instance) else util.Uninferable
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for item in class_seq
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]
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# strict compatibility with issubclass
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# issubclass(type, (object, 1)) evaluates to true
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# issubclass(object, (1, type)) raises TypeError
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for klass in class_seq:
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if klass is util.Uninferable:
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raise AstroidTypeError("arg 2 must be a type or tuple of types")
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for obj_subclass in obj_type.mro():
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if obj_subclass == klass:
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return True
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return False
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def object_isinstance(node, class_or_seq, context=None):
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"""Check if a node 'isinstance' any node in class_or_seq
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:param node: A given node
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:param class_or_seq: Union[nodes.NodeNG, Sequence[nodes.NodeNG]]
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:rtype: bool
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:raises AstroidTypeError: if the given ``classes_or_seq`` are not types
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"""
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obj_type = object_type(node, context)
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if obj_type is util.Uninferable:
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return util.Uninferable
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return _object_type_is_subclass(obj_type, class_or_seq, context=context)
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def object_issubclass(node, class_or_seq, context=None):
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"""Check if a type is a subclass of any node in class_or_seq
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:param node: A given node
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:param class_or_seq: Union[Nodes.NodeNG, Sequence[nodes.NodeNG]]
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:rtype: bool
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:raises AstroidTypeError: if the given ``classes_or_seq`` are not types
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:raises AstroidError: if the type of the given node cannot be inferred
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or its type's mro doesn't work
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"""
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if not isinstance(node, nodes.ClassDef):
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raise TypeError(f"{node} needs to be a ClassDef node")
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return _object_type_is_subclass(node, class_or_seq, context=context)
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def safe_infer(
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node: nodes.NodeNG | bases.Proxy, context: InferenceContext | None = None
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) -> InferenceResult | None:
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"""Return the inferred value for the given node.
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Return None if inference failed or if there is some ambiguity (more than
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one node has been inferred).
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"""
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try:
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inferit = node.infer(context=context)
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value = next(inferit)
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except (InferenceError, StopIteration):
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return None
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try:
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next(inferit)
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return None # None if there is ambiguity on the inferred node
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except InferenceError:
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return None # there is some kind of ambiguity
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except StopIteration:
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return value
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def has_known_bases(klass, context=None):
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"""Return true if all base classes of a class could be inferred."""
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try:
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return klass._all_bases_known
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except AttributeError:
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pass
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for base in klass.bases:
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result = safe_infer(base, context=context)
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# TODO: check for A->B->A->B pattern in class structure too?
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if (
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not isinstance(result, scoped_nodes.ClassDef)
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or result is klass
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or not has_known_bases(result, context=context)
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):
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klass._all_bases_known = False
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return False
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klass._all_bases_known = True
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return True
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def _type_check(type1, type2):
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if not all(map(has_known_bases, (type1, type2))):
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raise _NonDeducibleTypeHierarchy
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if not all([type1.newstyle, type2.newstyle]):
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return False
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try:
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return type1 in type2.mro()[:-1]
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except MroError as e:
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# The MRO is invalid.
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raise _NonDeducibleTypeHierarchy from e
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def is_subtype(type1, type2):
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"""Check if *type1* is a subtype of *type2*."""
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return _type_check(type1=type2, type2=type1)
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def is_supertype(type1, type2):
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"""Check if *type2* is a supertype of *type1*."""
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return _type_check(type1, type2)
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def class_instance_as_index(node):
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"""Get the value as an index for the given instance.
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If an instance provides an __index__ method, then it can
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be used in some scenarios where an integer is expected,
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for instance when multiplying or subscripting a list.
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"""
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context = InferenceContext()
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try:
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for inferred in node.igetattr("__index__", context=context):
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if not isinstance(inferred, bases.BoundMethod):
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continue
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context.boundnode = node
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context.callcontext = CallContext(args=[], callee=inferred)
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for result in inferred.infer_call_result(node, context=context):
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if isinstance(result, nodes.Const) and isinstance(result.value, int):
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return result
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except InferenceError:
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pass
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return None
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def object_len(node, context=None):
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"""Infer length of given node object
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:param Union[nodes.ClassDef, nodes.Instance] node:
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:param node: Node to infer length of
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:raises AstroidTypeError: If an invalid node is returned
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from __len__ method or no __len__ method exists
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:raises InferenceError: If the given node cannot be inferred
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or if multiple nodes are inferred or if the code executed in python
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would result in a infinite recursive check for length
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:rtype int: Integer length of node
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"""
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# pylint: disable=import-outside-toplevel; circular import
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from astroid.objects import FrozenSet
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inferred_node = safe_infer(node, context=context)
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# prevent self referential length calls from causing a recursion error
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# see https://github.com/PyCQA/astroid/issues/777
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node_frame = node.frame(future=True)
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if (
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isinstance(node_frame, scoped_nodes.FunctionDef)
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and node_frame.name == "__len__"
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and hasattr(inferred_node, "_proxied")
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and inferred_node._proxied == node_frame.parent
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):
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message = (
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"Self referential __len__ function will "
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"cause a RecursionError on line {} of {}".format(
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node.lineno, node.root().file
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)
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)
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raise InferenceError(message)
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if inferred_node is None or inferred_node is util.Uninferable:
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raise InferenceError(node=node)
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if isinstance(inferred_node, nodes.Const) and isinstance(
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inferred_node.value, (bytes, str)
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):
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return len(inferred_node.value)
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if isinstance(inferred_node, (nodes.List, nodes.Set, nodes.Tuple, FrozenSet)):
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return len(inferred_node.elts)
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if isinstance(inferred_node, nodes.Dict):
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return len(inferred_node.items)
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node_type = object_type(inferred_node, context=context)
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if not node_type:
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raise InferenceError(node=node)
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try:
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len_call = next(node_type.igetattr("__len__", context=context))
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except StopIteration as e:
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raise AstroidTypeError(str(e)) from e
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except AttributeInferenceError as e:
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raise AstroidTypeError(
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f"object of type '{node_type.pytype()}' has no len()"
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) from e
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inferred = len_call.infer_call_result(node, context)
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if inferred is util.Uninferable:
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raise InferenceError(node=node, context=context)
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result_of_len = next(inferred, None)
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if (
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isinstance(result_of_len, nodes.Const)
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and result_of_len.pytype() == "builtins.int"
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):
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return result_of_len.value
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if (
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result_of_len is None
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or isinstance(result_of_len, bases.Instance)
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and result_of_len.is_subtype_of("builtins.int")
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):
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# Fake a result as we don't know the arguments of the instance call.
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return 0
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raise AstroidTypeError(
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f"'{result_of_len}' object cannot be interpreted as an integer"
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)
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