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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 """This module contains base classes and functions for the nodes and some inference utils. """ from __future__ import annotations import collections import collections.abc import sys from collections.abc import Sequence from typing import TYPE_CHECKING, Any, ClassVar from astroid import decorators, nodes from astroid.const import PY310_PLUS from astroid.context import ( CallContext, InferenceContext, bind_context_to_node, copy_context, ) from astroid.exceptions import ( AstroidTypeError, AttributeInferenceError, InferenceError, NameInferenceError, ) from astroid.typing import InferBinaryOp, InferenceErrorInfo, InferenceResult from astroid.util import Uninferable, UninferableBase, lazy_descriptor, lazy_import if sys.version_info >= (3, 8): from typing import Literal else: from typing_extensions import Literal if TYPE_CHECKING: from astroid.constraint import Constraint objectmodel = lazy_import("interpreter.objectmodel") helpers = lazy_import("helpers") manager = lazy_import("manager") # TODO: check if needs special treatment BOOL_SPECIAL_METHOD = "__bool__" BUILTINS = "builtins" # TODO Remove in 2.8 PROPERTIES = {"builtins.property", "abc.abstractproperty"} if PY310_PLUS: PROPERTIES.add("enum.property") # List of possible property names. We use this list in order # to see if a method is a property or not. This should be # pretty reliable and fast, the alternative being to check each # decorator to see if its a real property-like descriptor, which # can be too complicated. # Also, these aren't qualified, because each project can # define them, we shouldn't expect to know every possible # property-like decorator! POSSIBLE_PROPERTIES = { "cached_property", "cachedproperty", "lazyproperty", "lazy_property", "reify", "lazyattribute", "lazy_attribute", "LazyProperty", "lazy", "cache_readonly", "DynamicClassAttribute", } def _is_property(meth, context: InferenceContext | None = None) -> bool: decoratornames = meth.decoratornames(context=context) if PROPERTIES.intersection(decoratornames): return True stripped = { name.split(".")[-1] for name in decoratornames if not isinstance(name, UninferableBase) } if any(name in stripped for name in POSSIBLE_PROPERTIES): return True # Lookup for subclasses of *property* if not meth.decorators: return False for decorator in meth.decorators.nodes or (): inferred = helpers.safe_infer(decorator, context=context) if inferred is None or isinstance(inferred, UninferableBase): continue if inferred.__class__.__name__ == "ClassDef": for base_class in inferred.bases: if base_class.__class__.__name__ != "Name": continue module, _ = base_class.lookup(base_class.name) if module.name == "builtins" and base_class.name == "property": return True return False class Proxy: """A simple proxy object. Note: Subclasses of this object will need a custom __getattr__ if new instance attributes are created. See the Const class """ _proxied: nodes.ClassDef | nodes.Lambda | Proxy | None = ( None # proxied object may be set by class or by instance ) def __init__( self, proxied: nodes.ClassDef | nodes.Lambda | Proxy | None = None ) -> None: if proxied is None: # This is a hack to allow calling this __init__ during bootstrapping of # builtin classes and their docstrings. # For Const, Generator, and UnionType nodes the _proxied attribute # is set during bootstrapping # as we first need to build the ClassDef that they can proxy. # Thus, if proxied is None self should be a Const or Generator # as that is the only way _proxied will be correctly set as a ClassDef. assert isinstance(self, (nodes.Const, Generator, UnionType)) else: self._proxied = proxied def __getattr__(self, name): if name == "_proxied": return self.__class__._proxied if name in self.__dict__: return self.__dict__[name] return getattr(self._proxied, name) def infer( # type: ignore[return] self, context: InferenceContext | None = None, **kwargs: Any ) -> collections.abc.Generator[InferenceResult, None, InferenceErrorInfo | None]: yield self def _infer_stmts( stmts: Sequence[nodes.NodeNG | UninferableBase | Instance], context: InferenceContext | None, frame: nodes.NodeNG | Instance | None = None, ) -> collections.abc.Generator[InferenceResult, None, None]: """Return an iterator on statements inferred by each statement in *stmts*.""" inferred = False constraint_failed = False if context is not None: name = context.lookupname context = context.clone() constraints = context.constraints.get(name, {}) else: name = None constraints = {} context = InferenceContext() for stmt in stmts: if isinstance(stmt, UninferableBase): yield stmt inferred = True continue # 'context' is always InferenceContext and Instances get '_infer_name' from ClassDef context.lookupname = stmt._infer_name(frame, name) # type: ignore[union-attr] try: stmt_constraints: set[Constraint] = set() for constraint_stmt, potential_constraints in constraints.items(): if not constraint_stmt.parent_of(stmt): stmt_constraints.update(potential_constraints) for inf in stmt.infer(context=context): if all(constraint.satisfied_by(inf) for constraint in stmt_constraints): yield inf inferred = True else: constraint_failed = True except NameInferenceError: continue except InferenceError: yield Uninferable inferred = True if not inferred and constraint_failed: yield Uninferable elif not inferred: raise InferenceError( "Inference failed for all members of {stmts!r}.", stmts=stmts, frame=frame, context=context, ) def _infer_method_result_truth(instance, method_name, context): # Get the method from the instance and try to infer # its return's truth value. meth = next(instance.igetattr(method_name, context=context), None) if meth and hasattr(meth, "infer_call_result"): if not meth.callable(): return Uninferable try: context.callcontext = CallContext(args=[], callee=meth) for value in meth.infer_call_result(instance, context=context): if isinstance(value, UninferableBase): return value try: inferred = next(value.infer(context=context)) except StopIteration as e: raise InferenceError(context=context) from e return inferred.bool_value() except InferenceError: pass return Uninferable class BaseInstance(Proxy): """An instance base class, which provides lookup methods for potential instances. """ special_attributes = None def display_type(self) -> str: return "Instance of" def getattr(self, name, context: InferenceContext | None = None, lookupclass=True): try: values = self._proxied.instance_attr(name, context) except AttributeInferenceError as exc: if self.special_attributes and name in self.special_attributes: return [self.special_attributes.lookup(name)] if lookupclass: # Class attributes not available through the instance # unless they are explicitly defined. return self._proxied.getattr(name, context, class_context=False) raise AttributeInferenceError( target=self, attribute=name, context=context ) from exc # since we've no context information, return matching class members as # well if lookupclass: try: return values + self._proxied.getattr( name, context, class_context=False ) except AttributeInferenceError: pass return values def igetattr(self, name, context: InferenceContext | None = None): """Inferred getattr.""" if not context: context = InferenceContext() try: context.lookupname = name # avoid recursively inferring the same attr on the same class if context.push(self._proxied): raise InferenceError( message="Cannot infer the same attribute again", node=self, context=context, ) # XXX frame should be self._proxied, or not ? get_attr = self.getattr(name, context, lookupclass=False) yield from _infer_stmts( self._wrap_attr(get_attr, context), context, frame=self ) except AttributeInferenceError: try: # fallback to class.igetattr since it has some logic to handle # descriptors # But only if the _proxied is the Class. if self._proxied.__class__.__name__ != "ClassDef": raise attrs = self._proxied.igetattr(name, context, class_context=False) yield from self._wrap_attr(attrs, context) except AttributeInferenceError as error: raise InferenceError(**vars(error)) from error def _wrap_attr(self, attrs, context: InferenceContext | None = None): """Wrap bound methods of attrs in a InstanceMethod proxies.""" for attr in attrs: if isinstance(attr, UnboundMethod): if _is_property(attr): yield from attr.infer_call_result(self, context) else: yield BoundMethod(attr, self) elif hasattr(attr, "name") and attr.name == "<lambda>": if attr.args.arguments and attr.args.arguments[0].name == "self": yield BoundMethod(attr, self) continue yield attr else: yield attr def infer_call_result( self, caller: nodes.Call | Proxy, context: InferenceContext | None = None ): """Infer what a class instance is returning when called.""" context = bind_context_to_node(context, self) inferred = False # If the call is an attribute on the instance, we infer the attribute itself if isinstance(caller, nodes.Call) and isinstance(caller.func, nodes.Attribute): for res in self.igetattr(caller.func.attrname, context): inferred = True yield res # Otherwise we infer the call to the __call__ dunder normally for node in self._proxied.igetattr("__call__", context): if isinstance(node, UninferableBase) or not node.callable(): continue for res in node.infer_call_result(caller, context): inferred = True yield res if not inferred: raise InferenceError(node=self, caller=caller, context=context) class Instance(BaseInstance): """A special node representing a class instance.""" _proxied: nodes.ClassDef # pylint: disable=unnecessary-lambda special_attributes = lazy_descriptor(lambda: objectmodel.InstanceModel()) def __init__(self, proxied: nodes.ClassDef | None) -> None: super().__init__(proxied) infer_binary_op: ClassVar[InferBinaryOp[Instance]] def __repr__(self) -> str: return "<Instance of {}.{} at 0x{}>".format( self._proxied.root().name, self._proxied.name, id(self) ) def __str__(self) -> str: return f"Instance of {self._proxied.root().name}.{self._proxied.name}" def callable(self) -> bool: try: self._proxied.getattr("__call__", class_context=False) return True except AttributeInferenceError: return False def pytype(self) -> str: return self._proxied.qname() def display_type(self) -> str: return "Instance of" def bool_value(self, context: InferenceContext | None = None): """Infer the truth value for an Instance. The truth value of an instance is determined by these conditions: * if it implements __bool__ on Python 3 or __nonzero__ on Python 2, then its bool value will be determined by calling this special method and checking its result. * when this method is not defined, __len__() is called, if it is defined, and the object is considered true if its result is nonzero. If a class defines neither __len__() nor __bool__(), all its instances are considered true. """ context = context or InferenceContext() context.boundnode = self try: result = _infer_method_result_truth(self, BOOL_SPECIAL_METHOD, context) except (InferenceError, AttributeInferenceError): # Fallback to __len__. try: result = _infer_method_result_truth(self, "__len__", context) except (AttributeInferenceError, InferenceError): return True return result def getitem(self, index, context: InferenceContext | None = None): new_context = bind_context_to_node(context, self) if not context: context = new_context method = next(self.igetattr("__getitem__", context=context), None) # Create a new CallContext for providing index as an argument. new_context.callcontext = CallContext(args=[index], callee=method) if not isinstance(method, BoundMethod): raise InferenceError( "Could not find __getitem__ for {node!r}.", node=self, context=context ) if len(method.args.arguments) != 2: # (self, index) raise AstroidTypeError( "__getitem__ for {node!r} does not have correct signature", node=self, context=context, ) return next(method.infer_call_result(self, new_context), None) class UnboundMethod(Proxy): """A special node representing a method not bound to an instance.""" # pylint: disable=unnecessary-lambda special_attributes = lazy_descriptor(lambda: objectmodel.UnboundMethodModel()) def __repr__(self) -> str: frame = self._proxied.parent.frame(future=True) return "<{} {} of {} at 0x{}".format( self.__class__.__name__, self._proxied.name, frame.qname(), id(self) ) def implicit_parameters(self) -> Literal[0]: return 0 def is_bound(self) -> Literal[False]: return False def getattr(self, name, context: InferenceContext | None = None): if name in self.special_attributes: return [self.special_attributes.lookup(name)] return self._proxied.getattr(name, context) def igetattr(self, name, context: InferenceContext | None = None): if name in self.special_attributes: return iter((self.special_attributes.lookup(name),)) return self._proxied.igetattr(name, context) def infer_call_result(self, caller, context): """ The boundnode of the regular context with a function called on ``object.__new__`` will be of type ``object``, which is incorrect for the argument in general. If no context is given the ``object.__new__`` call argument will be correctly inferred except when inside a call that requires the additional context (such as a classmethod) of the boundnode to determine which class the method was called from """ # If we're unbound method __new__ of a builtin, the result is an # instance of the class given as first argument. if self._proxied.name == "__new__": qname = self._proxied.parent.frame(future=True).qname() # Avoid checking builtins.type: _infer_type_new_call() does more validation if qname.startswith("builtins.") and qname != "builtins.type": return self._infer_builtin_new(caller, context) return self._proxied.infer_call_result(caller, context) def _infer_builtin_new( self, caller: nodes.Call, context: InferenceContext, ) -> collections.abc.Generator[ nodes.Const | Instance | UninferableBase, None, None ]: if not caller.args: return # Attempt to create a constant if len(caller.args) > 1: value = None if isinstance(caller.args[1], nodes.Const): value = caller.args[1].value else: inferred_arg = next(caller.args[1].infer(), None) if isinstance(inferred_arg, nodes.Const): value = inferred_arg.value if value is not None: yield nodes.const_factory(value) return node_context = context.extra_context.get(caller.args[0]) for inferred in caller.args[0].infer(context=node_context): if isinstance(inferred, UninferableBase): yield inferred if isinstance(inferred, nodes.ClassDef): yield Instance(inferred) raise InferenceError def bool_value(self, context: InferenceContext | None = None) -> Literal[True]: return True class BoundMethod(UnboundMethod): """A special node representing a method bound to an instance.""" # pylint: disable=unnecessary-lambda special_attributes = lazy_descriptor(lambda: objectmodel.BoundMethodModel()) def __init__(self, proxy, bound): super().__init__(proxy) self.bound = bound def implicit_parameters(self) -> Literal[0, 1]: if self.name == "__new__": # __new__ acts as a classmethod but the class argument is not implicit. return 0 return 1 def is_bound(self) -> Literal[True]: return True def _infer_type_new_call(self, caller, context): # noqa: C901 """Try to infer what type.__new__(mcs, name, bases, attrs) returns. In order for such call to be valid, the metaclass needs to be a subtype of ``type``, the name needs to be a string, the bases needs to be a tuple of classes """ # pylint: disable=import-outside-toplevel; circular import from astroid.nodes import Pass # Verify the metaclass try: mcs = next(caller.args[0].infer(context=context)) except StopIteration as e: raise InferenceError(context=context) from e if mcs.__class__.__name__ != "ClassDef": # Not a valid first argument. return None if not mcs.is_subtype_of("builtins.type"): # Not a valid metaclass. return None # Verify the name try: name = next(caller.args[1].infer(context=context)) except StopIteration as e: raise InferenceError(context=context) from e if name.__class__.__name__ != "Const": # Not a valid name, needs to be a const. return None if not isinstance(name.value, str): # Needs to be a string. return None # Verify the bases try: bases = next(caller.args[2].infer(context=context)) 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: InferenceContext | None = 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: InferenceContext | None = None) -> Literal[True]: 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: InferenceContext | None = 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) -> Literal[False]: return False def pytype(self) -> Literal["builtins.generator"]: return "builtins.generator" def display_type(self) -> str: return "Generator" def bool_value(self, context: InferenceContext | None = None) -> Literal[True]: return True def __repr__(self) -> str: return f"<Generator({self._proxied.name}) l.{self.lineno} at 0x{id(self)}>" def __str__(self) -> str: 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) -> str: return "AsyncGenerator" def __repr__(self) -> str: return f"<AsyncGenerator({self._proxied.name}) l.{self.lineno} at 0x{id(self)}>" def __str__(self) -> str: return f"AsyncGenerator({self._proxied.name})" class UnionType(BaseInstance): """Special node representing new style typing unions. Proxied class is set once for all in raw_building. """ _proxied: nodes.ClassDef def __init__( self, left: UnionType | nodes.ClassDef | nodes.Const, right: UnionType | nodes.ClassDef | nodes.Const, parent: nodes.NodeNG | None = None, ) -> None: super().__init__() self.parent = parent self.left = left self.right = right def callable(self) -> Literal[False]: return False def bool_value(self, context: InferenceContext | None = None) -> Literal[True]: return True def pytype(self) -> Literal["types.UnionType"]: return "types.UnionType" def display_type(self) -> str: return "UnionType" def __repr__(self) -> str: return f"<UnionType({self._proxied.name}) l.{self.lineno} at 0x{id(self)}>" def __str__(self) -> str: return f"UnionType({self._proxied.name})"
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