650 lines
23 KiB
Python
650 lines
23 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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"""This module contains base classes and functions for the nodes and some
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inference utils.
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"""
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from __future__ import annotations
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import collections
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import collections.abc
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import sys
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from collections.abc import Sequence
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from typing import Any
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from astroid import decorators, nodes
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from astroid.const import PY310_PLUS
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from astroid.context import (
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CallContext,
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InferenceContext,
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bind_context_to_node,
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copy_context,
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)
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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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NameInferenceError,
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)
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from astroid.typing import InferenceErrorInfo, InferenceResult
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from astroid.util import Uninferable, lazy_descriptor, lazy_import
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if sys.version_info >= (3, 8):
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from typing import Literal
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else:
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from typing_extensions import Literal
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objectmodel = lazy_import("interpreter.objectmodel")
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helpers = lazy_import("helpers")
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manager = lazy_import("manager")
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# TODO: check if needs special treatment
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BOOL_SPECIAL_METHOD = "__bool__"
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BUILTINS = "builtins" # TODO Remove in 2.8
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PROPERTIES = {"builtins.property", "abc.abstractproperty"}
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if PY310_PLUS:
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PROPERTIES.add("enum.property")
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# List of possible property names. We use this list in order
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# to see if a method is a property or not. This should be
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# pretty reliable and fast, the alternative being to check each
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# decorator to see if its a real property-like descriptor, which
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# can be too complicated.
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# Also, these aren't qualified, because each project can
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# define them, we shouldn't expect to know every possible
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# property-like decorator!
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POSSIBLE_PROPERTIES = {
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"cached_property",
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"cachedproperty",
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"lazyproperty",
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"lazy_property",
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"reify",
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"lazyattribute",
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"lazy_attribute",
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"LazyProperty",
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"lazy",
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"cache_readonly",
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"DynamicClassAttribute",
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}
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def _is_property(meth, context=None):
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decoratornames = meth.decoratornames(context=context)
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if PROPERTIES.intersection(decoratornames):
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return True
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stripped = {
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name.split(".")[-1] for name in decoratornames if name is not Uninferable
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}
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if any(name in stripped for name in POSSIBLE_PROPERTIES):
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return True
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# Lookup for subclasses of *property*
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if not meth.decorators:
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return False
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for decorator in meth.decorators.nodes or ():
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inferred = helpers.safe_infer(decorator, context=context)
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if inferred is None or inferred is Uninferable:
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continue
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if inferred.__class__.__name__ == "ClassDef":
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for base_class in inferred.bases:
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if base_class.__class__.__name__ != "Name":
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continue
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module, _ = base_class.lookup(base_class.name)
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if module.name == "builtins" and base_class.name == "property":
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return True
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return False
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class Proxy:
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"""a simple proxy object
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Note:
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Subclasses of this object will need a custom __getattr__
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if new instance attributes are created. See the Const class
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"""
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_proxied: nodes.ClassDef | nodes.Lambda | Proxy | None = (
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None # proxied object may be set by class or by instance
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)
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def __init__(
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self, proxied: nodes.ClassDef | nodes.Lambda | Proxy | None = None
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) -> None:
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if proxied is None:
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# This is a hack to allow calling this __init__ during bootstrapping of
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# builtin classes and their docstrings.
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# For Const and Generator nodes the _proxied attribute is set during bootstrapping
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# as we first need to build the ClassDef that they can proxy.
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# Thus, if proxied is None self should be a Const or Generator
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# as that is the only way _proxied will be correctly set as a ClassDef.
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assert isinstance(self, (nodes.Const, Generator))
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else:
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self._proxied = proxied
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def __getattr__(self, name):
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if name == "_proxied":
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return self.__class__._proxied
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if name in self.__dict__:
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return self.__dict__[name]
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return getattr(self._proxied, name)
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def infer( # type: ignore[return]
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self, context: InferenceContext | None = None, **kwargs: Any
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) -> collections.abc.Generator[InferenceResult, None, InferenceErrorInfo | None]:
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yield self
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def _infer_stmts(
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stmts: Sequence[nodes.NodeNG | type[Uninferable] | Instance],
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context: InferenceContext | None,
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frame: nodes.NodeNG | Instance | None = None,
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) -> collections.abc.Generator[InferenceResult, None, None]:
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"""Return an iterator on statements inferred by each statement in *stmts*."""
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inferred = False
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if context is not None:
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name = context.lookupname
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context = context.clone()
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else:
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name = None
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context = InferenceContext()
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for stmt in stmts:
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if stmt is Uninferable:
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yield stmt
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inferred = True
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continue
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# 'context' is always InferenceContext and Instances get '_infer_name' from ClassDef
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context.lookupname = stmt._infer_name(frame, name) # type: ignore[union-attr]
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try:
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# Mypy doesn't recognize that 'stmt' can't be Uninferable
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for inf in stmt.infer(context=context): # type: ignore[union-attr]
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yield inf
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inferred = True
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except NameInferenceError:
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continue
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except InferenceError:
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yield Uninferable
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inferred = True
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if not inferred:
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raise InferenceError(
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"Inference failed for all members of {stmts!r}.",
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stmts=stmts,
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frame=frame,
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context=context,
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)
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def _infer_method_result_truth(instance, method_name, context):
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# Get the method from the instance and try to infer
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# its return's truth value.
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meth = next(instance.igetattr(method_name, context=context), None)
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if meth and hasattr(meth, "infer_call_result"):
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if not meth.callable():
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return Uninferable
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try:
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context.callcontext = CallContext(args=[], callee=meth)
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for value in meth.infer_call_result(instance, context=context):
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if value is Uninferable:
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return value
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try:
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inferred = next(value.infer(context=context))
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except StopIteration as e:
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raise InferenceError(context=context) from e
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return inferred.bool_value()
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except InferenceError:
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pass
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return Uninferable
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class BaseInstance(Proxy):
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"""An instance base class, which provides lookup methods for potential instances."""
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special_attributes = None
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def display_type(self):
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return "Instance of"
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def getattr(self, name, context=None, lookupclass=True):
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try:
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values = self._proxied.instance_attr(name, context)
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except AttributeInferenceError as exc:
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if self.special_attributes and name in self.special_attributes:
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return [self.special_attributes.lookup(name)]
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if lookupclass:
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# Class attributes not available through the instance
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# unless they are explicitly defined.
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return self._proxied.getattr(name, context, class_context=False)
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raise AttributeInferenceError(
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target=self, attribute=name, context=context
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) from exc
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# since we've no context information, return matching class members as
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# well
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if lookupclass:
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try:
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return values + self._proxied.getattr(
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name, context, class_context=False
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)
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except AttributeInferenceError:
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pass
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return values
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def igetattr(self, name, context=None):
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"""inferred getattr"""
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if not context:
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context = InferenceContext()
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try:
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context.lookupname = name
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# avoid recursively inferring the same attr on the same class
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if context.push(self._proxied):
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raise InferenceError(
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message="Cannot infer the same attribute again",
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node=self,
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context=context,
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)
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# XXX frame should be self._proxied, or not ?
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get_attr = self.getattr(name, context, lookupclass=False)
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yield from _infer_stmts(
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self._wrap_attr(get_attr, context), context, frame=self
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)
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except AttributeInferenceError:
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try:
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# fallback to class.igetattr since it has some logic to handle
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# descriptors
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# But only if the _proxied is the Class.
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if self._proxied.__class__.__name__ != "ClassDef":
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raise
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attrs = self._proxied.igetattr(name, context, class_context=False)
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yield from self._wrap_attr(attrs, context)
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except AttributeInferenceError as error:
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raise InferenceError(**vars(error)) from error
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def _wrap_attr(self, attrs, context=None):
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"""wrap bound methods of attrs in a InstanceMethod proxies"""
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for attr in attrs:
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if isinstance(attr, UnboundMethod):
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if _is_property(attr):
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yield from attr.infer_call_result(self, context)
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else:
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yield BoundMethod(attr, self)
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elif hasattr(attr, "name") and attr.name == "<lambda>":
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if attr.args.arguments and attr.args.arguments[0].name == "self":
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yield BoundMethod(attr, self)
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continue
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yield attr
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else:
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yield attr
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def infer_call_result(
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self, caller: nodes.Call | Proxy, context: InferenceContext | None = None
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):
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"""infer what a class instance is returning when called"""
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context = bind_context_to_node(context, self)
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inferred = False
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# If the call is an attribute on the instance, we infer the attribute itself
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if isinstance(caller, nodes.Call) and isinstance(caller.func, nodes.Attribute):
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for res in self.igetattr(caller.func.attrname, context):
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inferred = True
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yield res
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# Otherwise we infer the call to the __call__ dunder normally
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for node in self._proxied.igetattr("__call__", context):
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if node is Uninferable or not node.callable():
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continue
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for res in node.infer_call_result(caller, context):
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inferred = True
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yield res
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if not inferred:
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raise InferenceError(node=self, caller=caller, context=context)
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class Instance(BaseInstance):
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"""A special node representing a class instance."""
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_proxied: nodes.ClassDef
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# pylint: disable=unnecessary-lambda
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special_attributes = lazy_descriptor(lambda: objectmodel.InstanceModel())
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def __init__(self, proxied: nodes.ClassDef | None) -> None:
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super().__init__(proxied)
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def __repr__(self):
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return "<Instance of {}.{} at 0x{}>".format(
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self._proxied.root().name, self._proxied.name, id(self)
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)
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def __str__(self):
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return f"Instance of {self._proxied.root().name}.{self._proxied.name}"
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def callable(self):
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try:
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self._proxied.getattr("__call__", class_context=False)
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return True
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except AttributeInferenceError:
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return False
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def pytype(self) -> str:
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return self._proxied.qname()
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def display_type(self):
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return "Instance of"
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def bool_value(self, context=None):
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"""Infer the truth value for an Instance
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The truth value of an instance is determined by these conditions:
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* if it implements __bool__ on Python 3 or __nonzero__
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on Python 2, then its bool value will be determined by
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calling this special method and checking its result.
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* when this method is not defined, __len__() is called, if it
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is defined, and the object is considered true if its result is
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nonzero. If a class defines neither __len__() nor __bool__(),
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all its instances are considered true.
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"""
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context = context or InferenceContext()
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context.boundnode = self
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try:
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result = _infer_method_result_truth(self, BOOL_SPECIAL_METHOD, context)
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except (InferenceError, AttributeInferenceError):
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# Fallback to __len__.
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try:
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result = _infer_method_result_truth(self, "__len__", context)
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except (AttributeInferenceError, InferenceError):
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return True
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return result
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def getitem(self, index, context=None):
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new_context = bind_context_to_node(context, self)
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if not context:
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context = new_context
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method = next(self.igetattr("__getitem__", context=context), None)
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# Create a new CallContext for providing index as an argument.
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new_context.callcontext = CallContext(args=[index], callee=method)
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if not isinstance(method, BoundMethod):
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raise InferenceError(
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"Could not find __getitem__ for {node!r}.", node=self, context=context
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)
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if len(method.args.arguments) != 2: # (self, index)
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raise AstroidTypeError(
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"__getitem__ for {node!r} does not have correct signature",
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node=self,
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context=context,
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)
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return next(method.infer_call_result(self, new_context), None)
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class UnboundMethod(Proxy):
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"""a special node representing a method not bound to an instance"""
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# pylint: disable=unnecessary-lambda
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special_attributes = lazy_descriptor(lambda: objectmodel.UnboundMethodModel())
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def __repr__(self):
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frame = self._proxied.parent.frame(future=True)
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return "<{} {} of {} at 0x{}".format(
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self.__class__.__name__, self._proxied.name, frame.qname(), id(self)
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)
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def implicit_parameters(self) -> Literal[0]:
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return 0
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def is_bound(self):
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return False
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def getattr(self, name, context=None):
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if name in self.special_attributes:
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return [self.special_attributes.lookup(name)]
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return self._proxied.getattr(name, context)
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def igetattr(self, name, context=None):
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if name in self.special_attributes:
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return iter((self.special_attributes.lookup(name),))
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return self._proxied.igetattr(name, context)
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def infer_call_result(self, caller, context):
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"""
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The boundnode of the regular context with a function called
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on ``object.__new__`` will be of type ``object``,
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which is incorrect for the argument in general.
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If no context is given the ``object.__new__`` call argument will
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be correctly inferred except when inside a call that requires
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the additional context (such as a classmethod) of the boundnode
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to determine which class the method was called from
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"""
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# If we're unbound method __new__ of a builtin, the result is an
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# instance of the class given as first argument.
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if self._proxied.name == "__new__":
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qname = self._proxied.parent.frame(future=True).qname()
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# Avoid checking builtins.type: _infer_type_new_call() does more validation
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if qname.startswith("builtins.") and qname != "builtins.type":
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return self._infer_builtin_new(caller, context)
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return self._proxied.infer_call_result(caller, context)
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def _infer_builtin_new(
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self,
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caller: nodes.Call,
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context: InferenceContext,
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) -> collections.abc.Generator[
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nodes.Const | Instance | type[Uninferable], None, None
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]:
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if not caller.args:
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return
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# Attempt to create a constant
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if len(caller.args) > 1:
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value = None
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if isinstance(caller.args[1], nodes.Const):
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value = caller.args[1].value
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else:
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inferred_arg = next(caller.args[1].infer(), None)
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if isinstance(inferred_arg, nodes.Const):
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value = inferred_arg.value
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if value is not None:
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yield nodes.const_factory(value)
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return
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node_context = context.extra_context.get(caller.args[0])
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for inferred in caller.args[0].infer(context=node_context):
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if inferred is Uninferable:
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yield inferred
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if isinstance(inferred, nodes.ClassDef):
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yield Instance(inferred)
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raise InferenceError
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def bool_value(self, context=None):
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return True
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class BoundMethod(UnboundMethod):
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"""a special node representing a method bound to an instance"""
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# pylint: disable=unnecessary-lambda
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special_attributes = lazy_descriptor(lambda: objectmodel.BoundMethodModel())
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def __init__(self, proxy, bound):
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super().__init__(proxy)
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self.bound = bound
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def implicit_parameters(self) -> Literal[0, 1]:
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if self.name == "__new__":
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# __new__ acts as a classmethod but the class argument is not implicit.
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return 0
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return 1
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def is_bound(self):
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return True
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def _infer_type_new_call(self, caller, context):
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"""Try to infer what type.__new__(mcs, name, bases, attrs) returns.
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In order for such call to be valid, the metaclass needs to be
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a subtype of ``type``, the name needs to be a string, the bases
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needs to be a tuple of classes
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"""
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# pylint: disable=import-outside-toplevel; circular import
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from astroid.nodes import Pass
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# Verify the metaclass
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try:
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mcs = next(caller.args[0].infer(context=context))
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except StopIteration as e:
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raise InferenceError(context=context) from e
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if mcs.__class__.__name__ != "ClassDef":
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# Not a valid first argument.
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return None
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if not mcs.is_subtype_of("builtins.type"):
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# Not a valid metaclass.
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return None
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# Verify the name
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try:
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name = next(caller.args[1].infer(context=context))
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except StopIteration as e:
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raise InferenceError(context=context) from e
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if name.__class__.__name__ != "Const":
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# Not a valid name, needs to be a const.
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return None
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if not isinstance(name.value, str):
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# Needs to be a string.
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return None
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# Verify the bases
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try:
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bases = next(caller.args[2].infer(context=context))
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except StopIteration as e:
|
|
raise InferenceError(context=context) from e
|
|
if bases.__class__.__name__ != "Tuple":
|
|
# Needs to be a tuple.
|
|
return None
|
|
try:
|
|
inferred_bases = [next(elt.infer(context=context)) for elt in bases.elts]
|
|
except StopIteration as e:
|
|
raise InferenceError(context=context) from e
|
|
if any(base.__class__.__name__ != "ClassDef" for base in inferred_bases):
|
|
# All the bases needs to be Classes
|
|
return None
|
|
|
|
# Verify the attributes.
|
|
try:
|
|
attrs = next(caller.args[3].infer(context=context))
|
|
except StopIteration as e:
|
|
raise InferenceError(context=context) from e
|
|
if attrs.__class__.__name__ != "Dict":
|
|
# Needs to be a dictionary.
|
|
return None
|
|
cls_locals = collections.defaultdict(list)
|
|
for key, value in attrs.items:
|
|
try:
|
|
key = next(key.infer(context=context))
|
|
except StopIteration as e:
|
|
raise InferenceError(context=context) from e
|
|
try:
|
|
value = next(value.infer(context=context))
|
|
except StopIteration as e:
|
|
raise InferenceError(context=context) from e
|
|
# Ignore non string keys
|
|
if key.__class__.__name__ == "Const" and isinstance(key.value, str):
|
|
cls_locals[key.value].append(value)
|
|
|
|
# Build the class from now.
|
|
cls = mcs.__class__(
|
|
name=name.value,
|
|
lineno=caller.lineno,
|
|
col_offset=caller.col_offset,
|
|
parent=caller,
|
|
)
|
|
empty = Pass()
|
|
cls.postinit(
|
|
bases=bases.elts,
|
|
body=[empty],
|
|
decorators=[],
|
|
newstyle=True,
|
|
metaclass=mcs,
|
|
keywords=[],
|
|
)
|
|
cls.locals = cls_locals
|
|
return cls
|
|
|
|
def infer_call_result(self, caller, context=None):
|
|
context = bind_context_to_node(context, self.bound)
|
|
if (
|
|
self.bound.__class__.__name__ == "ClassDef"
|
|
and self.bound.name == "type"
|
|
and self.name == "__new__"
|
|
and len(caller.args) == 4
|
|
):
|
|
# Check if we have a ``type.__new__(mcs, name, bases, attrs)`` call.
|
|
new_cls = self._infer_type_new_call(caller, context)
|
|
if new_cls:
|
|
return iter((new_cls,))
|
|
|
|
return super().infer_call_result(caller, context)
|
|
|
|
def bool_value(self, context=None):
|
|
return True
|
|
|
|
|
|
class Generator(BaseInstance):
|
|
"""a special node representing a generator.
|
|
|
|
Proxied class is set once for all in raw_building.
|
|
"""
|
|
|
|
_proxied: nodes.ClassDef
|
|
|
|
special_attributes = lazy_descriptor(objectmodel.GeneratorModel)
|
|
|
|
def __init__(self, parent=None, generator_initial_context=None):
|
|
super().__init__()
|
|
self.parent = parent
|
|
self._call_context = copy_context(generator_initial_context)
|
|
|
|
@decorators.cached
|
|
def infer_yield_types(self):
|
|
yield from self.parent.infer_yield_result(self._call_context)
|
|
|
|
def callable(self):
|
|
return False
|
|
|
|
def pytype(self) -> Literal["builtins.generator"]:
|
|
return "builtins.generator"
|
|
|
|
def display_type(self):
|
|
return "Generator"
|
|
|
|
def bool_value(self, context=None):
|
|
return True
|
|
|
|
def __repr__(self):
|
|
return f"<Generator({self._proxied.name}) l.{self.lineno} at 0x{id(self)}>"
|
|
|
|
def __str__(self):
|
|
return f"Generator({self._proxied.name})"
|
|
|
|
|
|
class AsyncGenerator(Generator):
|
|
"""Special node representing an async generator"""
|
|
|
|
def pytype(self) -> Literal["builtins.async_generator"]:
|
|
return "builtins.async_generator"
|
|
|
|
def display_type(self):
|
|
return "AsyncGenerator"
|
|
|
|
def __repr__(self):
|
|
return f"<AsyncGenerator({self._proxied.name}) l.{self.lineno} at 0x{id(self)}>"
|
|
|
|
def __str__(self):
|
|
return f"AsyncGenerator({self._proxied.name})"
|