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Diffstat (limited to 'astroid/bases.py')
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diff --git a/astroid/bases.py b/astroid/bases.py new file mode 100644 index 00000000..c39e887a --- /dev/null +++ b/astroid/bases.py @@ -0,0 +1,599 @@ +# Copyright (c) 2009-2011, 2013-2014 LOGILAB S.A. (Paris, FRANCE) <contact@logilab.fr> +# Copyright (c) 2012 FELD Boris <lothiraldan@gmail.com> +# Copyright (c) 2014-2020 Claudiu Popa <pcmanticore@gmail.com> +# Copyright (c) 2014 Google, Inc. +# Copyright (c) 2014 Eevee (Alex Munroe) <amunroe@yelp.com> +# Copyright (c) 2015-2016 Ceridwen <ceridwenv@gmail.com> +# Copyright (c) 2015 Florian Bruhin <me@the-compiler.org> +# Copyright (c) 2016-2017 Derek Gustafson <degustaf@gmail.com> +# Copyright (c) 2017 Calen Pennington <calen.pennington@gmail.com> +# Copyright (c) 2018-2019 Nick Drozd <nicholasdrozd@gmail.com> +# Copyright (c) 2018-2019 hippo91 <guillaume.peillex@gmail.com> +# Copyright (c) 2018 Ville Skyttä <ville.skytta@iki.fi> +# Copyright (c) 2018 Bryce Guinta <bryce.paul.guinta@gmail.com> +# Copyright (c) 2018 Daniel Colascione <dancol@dancol.org> +# Copyright (c) 2019 Hugo van Kemenade <hugovk@users.noreply.github.com> +# Copyright (c) 2021 Pierre Sassoulas <pierre.sassoulas@gmail.com> +# Copyright (c) 2021 pre-commit-ci[bot] <bot@noreply.github.com> +# Copyright (c) 2021 Daniël van Noord <13665637+DanielNoord@users.noreply.github.com> +# Copyright (c) 2021 David Liu <david@cs.toronto.edu> +# Copyright (c) 2021 doranid <ddandd@gmail.com> +# Copyright (c) 2021 Marc Mueller <30130371+cdce8p@users.noreply.github.com> +# Copyright (c) 2021 Andrew Haigh <hello@nelf.in> + +# 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 + +"""This module contains base classes and functions for the nodes and some +inference utils. +""" + +import collections + +from astroid import decorators +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.util import Uninferable, lazy_descriptor, lazy_import + +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=None): + decoratornames = meth.decoratornames(context=context) + if PROPERTIES.intersection(decoratornames): + return True + stripped = { + name.split(".")[-1] for name in decoratornames if name is not Uninferable + } + 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 inferred is Uninferable: + 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 = None # proxied object may be set by class or by instance + + def __init__(self, proxied=None): + if proxied is not None: + 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(self, context=None): + yield self + + +def _infer_stmts(stmts, context, frame=None): + """Return an iterator on statements inferred by each statement in *stmts*.""" + inferred = False + if context is not None: + name = context.lookupname + context = context.clone() + else: + name = None + context = InferenceContext() + + for stmt in stmts: + if stmt is Uninferable: + yield stmt + inferred = True + continue + context.lookupname = stmt._infer_name(frame, name) + try: + for inf in stmt.infer(context=context): + yield inf + inferred = True + except NameInferenceError: + continue + except InferenceError: + yield Uninferable + inferred = True + if 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 value is Uninferable: + 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): + return "Instance of" + + def getattr(self, name, context=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=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=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, context=None): + """infer what a class instance is returning when called""" + context = bind_context_to_node(context, self) + inferred = False + for node in self._proxied.igetattr("__call__", context): + if node is Uninferable 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.""" + + # pylint: disable=unnecessary-lambda + special_attributes = lazy_descriptor(lambda: objectmodel.InstanceModel()) + + def __repr__(self): + return "<Instance of {}.{} at 0x{}>".format( + self._proxied.root().name, self._proxied.name, id(self) + ) + + def __str__(self): + return f"Instance of {self._proxied.root().name}.{self._proxied.name}" + + def callable(self): + try: + self._proxied.getattr("__call__", class_context=False) + return True + except AttributeInferenceError: + return False + + def pytype(self): + return self._proxied.qname() + + def display_type(self): + return "Instance of" + + def bool_value(self, context=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=None): + # TODO: Rewrap index to Const for this case + 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): + frame = self._proxied.parent.frame() + return "<{} {} of {} at 0x{}".format( + self.__class__.__name__, self._proxied.name, frame.qname(), id(self) + ) + + def implicit_parameters(self): + return 0 + + def is_bound(self): + return False + + def getattr(self, name, context=None): + if name in self.special_attributes: + return [self.special_attributes.lookup(name)] + return self._proxied.getattr(name, context) + + def igetattr(self, name, context=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 + 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 builtin object, the result is an + # instance of the class given as first argument. + if ( + self._proxied.name == "__new__" + and self._proxied.parent.frame().qname() == "builtins.object" + ): + if caller.args: + node_context = context.extra_context.get(caller.args[0]) + infer = caller.args[0].infer(context=node_context) + else: + infer = [] + return (Instance(x) if x is not Uninferable else x for x in infer) + return self._proxied.infer_call_result(caller, context) + + def bool_value(self, context=None): + 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): + if self.name == "__new__": + # __new__ acts as a classmethod but the class argument is not implicit. + return 0 + return 1 + + def is_bound(self): + return True + + def _infer_type_new_call(self, caller, context): + """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=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. + """ + + 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): + 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): + 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})" |