# Copyright (c) 2015-2016 Cara Vinson # Copyright (c) 2015-2016 Claudiu Popa # Licensed under the LGPL: https://www.gnu.org/licenses/old-licenses/lgpl-2.1.en.html # For details: https://github.com/PyCQA/astroid/blob/master/COPYING.LESSER """ Inference objects are a way to represent composite AST nodes, which are used only as inference results, so they can't be found in the original AST tree. For instance, inferring the following frozenset use, leads to an inferred FrozenSet: Call(func=Name('frozenset'), args=Tuple(...)) """ import six from astroid import bases from astroid import decorators from astroid import exceptions from astroid import MANAGER from astroid import node_classes from astroid import scoped_nodes from astroid import util BUILTINS = six.moves.builtins.__name__ objectmodel = util.lazy_import('interpreter.objectmodel') class FrozenSet(node_classes._BaseContainer): """class representing a FrozenSet composite node""" def pytype(self): return '%s.frozenset' % BUILTINS def _infer(self, context=None): yield self @decorators.cachedproperty def _proxied(self): # pylint: disable=method-hidden builtins = MANAGER.astroid_cache[BUILTINS] return builtins.getattr('frozenset')[0] class Super(node_classes.NodeNG): """Proxy class over a super call. This class offers almost the same behaviour as Python's super, which is MRO lookups for retrieving attributes from the parents. The *mro_pointer* is the place in the MRO from where we should start looking, not counting it. *mro_type* is the object which provides the MRO, it can be both a type or an instance. *self_class* is the class where the super call is, while *scope* is the function where the super call is. """ # pylint: disable=unnecessary-lambda special_attributes = util.lazy_descriptor(lambda: objectmodel.SuperModel()) # pylint: disable=super-init-not-called def __init__(self, mro_pointer, mro_type, self_class, scope): self.type = mro_type self.mro_pointer = mro_pointer self._class_based = False self._self_class = self_class self._scope = scope def _infer(self, context=None): yield self def super_mro(self): """Get the MRO which will be used to lookup attributes in this super.""" if not isinstance(self.mro_pointer, scoped_nodes.ClassDef): raise exceptions.SuperError( "The first argument to super must be a subtype of " "type, not {mro_pointer}.", super_=self) if isinstance(self.type, scoped_nodes.ClassDef): # `super(type, type)`, most likely in a class method. self._class_based = True mro_type = self.type else: mro_type = getattr(self.type, '_proxied', None) if not isinstance(mro_type, (bases.Instance, scoped_nodes.ClassDef)): raise exceptions.SuperError( "The second argument to super must be an " "instance or subtype of type, not {type}.", super_=self) if not mro_type.newstyle: raise exceptions.SuperError("Unable to call super on old-style classes.", super_=self) mro = mro_type.mro() if self.mro_pointer not in mro: raise exceptions.SuperError( "The second argument to super must be an " "instance or subtype of type, not {type}.", super_=self) index = mro.index(self.mro_pointer) return mro[index + 1:] @decorators.cachedproperty def _proxied(self): builtins = MANAGER.astroid_cache[BUILTINS] return builtins.getattr('super')[0] def pytype(self): return '%s.super' % BUILTINS def display_type(self): return 'Super of' @property def name(self): """Get the name of the MRO pointer.""" return self.mro_pointer.name def igetattr(self, name, context=None): """Retrieve the inferred values of the given attribute name.""" if name in self.special_attributes: yield self.special_attributes.lookup(name) return try: mro = self.super_mro() # Don't let invalid MROs or invalid super calls # leak out as is from this function. except exceptions.SuperError as exc: util.reraise(exceptions.AttributeInferenceError( ('Lookup for {name} on {target!r} because super call {super!r} ' 'is invalid.'), target=self, attribute=name, context=context, super_=exc.super_)) except exceptions.MroError as exc: util.reraise(exceptions.AttributeInferenceError( ('Lookup for {name} on {target!r} failed because {cls!r} has an ' 'invalid MRO.'), target=self, attribute=name, context=context, mros=exc.mros, cls=exc.cls)) found = False for cls in mro: if name not in cls.locals: continue found = True for inferred in bases._infer_stmts([cls[name]], context, frame=self): if not isinstance(inferred, scoped_nodes.FunctionDef): yield inferred continue # We can obtain different descriptors from a super depending # on what we are accessing and where the super call is. if inferred.type == 'classmethod': yield bases.BoundMethod(inferred, cls) elif self._scope.type == 'classmethod' and inferred.type == 'method': yield inferred elif self._class_based or inferred.type == 'staticmethod': yield inferred elif bases._is_property(inferred): # TODO: support other descriptors as well. for value in inferred.infer_call_result(self, context): yield value else: yield bases.BoundMethod(inferred, cls) if not found: raise exceptions.AttributeInferenceError(target=self, attribute=name, context=context) def getattr(self, name, context=None): return list(self.igetattr(name, context=context)) class ExceptionInstance(bases.Instance): """Class for instances of exceptions It has special treatment for some of the exceptions's attributes, which are transformed at runtime into certain concrete objects, such as the case of .args. """ # pylint: disable=unnecessary-lambda special_attributes = util.lazy_descriptor(lambda: objectmodel.ExceptionInstanceModel()) class DictInstance(bases.Instance): """Special kind of instances for dictionaries This instance knows the underlying object model of the dictionaries, which means that methods such as .values or .items can be properly inferred. """ # pylint: disable=unnecessary-lambda special_attributes = util.lazy_descriptor(lambda: objectmodel.DictModel()) # Custom objects tailored for dictionaries, which are used to # disambiguate between the types of Python 2 dict's method returns # and Python 3 (where they return set like objects). class DictItems(bases.Proxy): __str__ = node_classes.NodeNG.__str__ __repr__ = node_classes.NodeNG.__repr__ class DictKeys(bases.Proxy): __str__ = node_classes.NodeNG.__str__ __repr__ = node_classes.NodeNG.__repr__ class DictValues(bases.Proxy): __str__ = node_classes.NodeNG.__str__ __repr__ = node_classes.NodeNG.__repr__ # TODO: Hack to solve the circular import problem between node_classes and objects # This is not needed in 2.0, which has a cleaner design overall node_classes.Dict.__bases__ = (node_classes.NodeNG, DictInstance)