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Diffstat (limited to 'src/main/python/venv/Lib/site-packages/astroid/inference.py')
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diff --git a/src/main/python/venv/Lib/site-packages/astroid/inference.py b/src/main/python/venv/Lib/site-packages/astroid/inference.py new file mode 100644 index 0000000..77c6b1d --- /dev/null +++ b/src/main/python/venv/Lib/site-packages/astroid/inference.py @@ -0,0 +1,943 @@ +# -*- coding: utf-8 -*- +# Copyright (c) 2006-2011, 2013-2014 LOGILAB S.A. (Paris, FRANCE) <contact@logilab.fr> +# Copyright (c) 2012 FELD Boris <lothiraldan@gmail.com> +# Copyright (c) 2013-2014 Google, Inc. +# Copyright (c) 2014-2018 Claudiu Popa <pcmanticore@gmail.com> +# Copyright (c) 2014 Eevee (Alex Munroe) <amunroe@yelp.com> +# Copyright (c) 2015-2016 Ceridwen <ceridwenv@gmail.com> +# Copyright (c) 2015 Dmitry Pribysh <dmand@yandex.ru> +# Copyright (c) 2016 Jakub Wilk <jwilk@jwilk.net> +# Copyright (c) 2017 Michał Masłowski <m.maslowski@clearcode.cc> +# Copyright (c) 2017 Calen Pennington <cale@edx.org> +# Copyright (c) 2017 Łukasz Rogalski <rogalski.91@gmail.com> +# Copyright (c) 2018 Bryce Guinta <bryce.paul.guinta@gmail.com> +# Copyright (c) 2018 Nick Drozd <nicholasdrozd@gmail.com> +# Copyright (c) 2018 Ashley Whetter <ashley@awhetter.co.uk> +# Copyright (c) 2018 HoverHell <hoverhell@gmail.com> + +# 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 + +"""this module contains a set of functions to handle inference on astroid trees +""" + +import functools +import itertools +import operator + +from astroid import bases +from astroid import context as contextmod +from astroid import exceptions +from astroid import decorators +from astroid import helpers +from astroid import manager +from astroid import nodes +from astroid.interpreter import dunder_lookup +from astroid import protocols +from astroid import util + + +MANAGER = manager.AstroidManager() + + +# .infer method ############################################################### + + +def infer_end(self, context=None): + """inference's end for node such as Module, ClassDef, FunctionDef, + Const... + + """ + yield self + + +nodes.Module._infer = infer_end +nodes.ClassDef._infer = infer_end +nodes.FunctionDef._infer = infer_end +nodes.Lambda._infer = infer_end +nodes.Const._infer = infer_end +nodes.Slice._infer = infer_end + + +def _infer_sequence_helper(node, context=None): + """Infer all values based on _BaseContainer.elts""" + values = [] + + for elt in node.elts: + if isinstance(elt, nodes.Starred): + starred = helpers.safe_infer(elt.value, context) + if not starred: + raise exceptions.InferenceError(node=node, context=context) + if not hasattr(starred, "elts"): + raise exceptions.InferenceError(node=node, context=context) + values.extend(_infer_sequence_helper(starred)) + elif isinstance(elt, nodes.NamedExpr): + value = helpers.safe_infer(elt.value, context) + if not value: + raise exceptions.InferenceError(node=node, context=context) + values.append(value) + else: + values.append(elt) + return values + + +@decorators.raise_if_nothing_inferred +def infer_sequence(self, context=None): + has_starred_named_expr = any( + isinstance(e, (nodes.Starred, nodes.NamedExpr)) for e in self.elts + ) + if has_starred_named_expr: + values = _infer_sequence_helper(self, context) + new_seq = type(self)( + lineno=self.lineno, col_offset=self.col_offset, parent=self.parent + ) + new_seq.postinit(values) + + yield new_seq + else: + yield self + + +nodes.List._infer = infer_sequence +nodes.Tuple._infer = infer_sequence +nodes.Set._infer = infer_sequence + + +def infer_map(self, context=None): + if not any(isinstance(k, nodes.DictUnpack) for k, _ in self.items): + yield self + else: + items = _infer_map(self, context) + new_seq = type(self)(self.lineno, self.col_offset, self.parent) + new_seq.postinit(list(items.items())) + yield new_seq + + +def _update_with_replacement(lhs_dict, rhs_dict): + """Delete nodes that equate to duplicate keys + + Since an astroid node doesn't 'equal' another node with the same value, + this function uses the as_string method to make sure duplicate keys + don't get through + + Note that both the key and the value are astroid nodes + + Fixes issue with DictUnpack causing duplicte keys + in inferred Dict items + + :param dict(nodes.NodeNG, nodes.NodeNG) lhs_dict: Dictionary to 'merge' nodes into + :param dict(nodes.NodeNG, nodes.NodeNG) rhs_dict: Dictionary with nodes to pull from + :return dict(nodes.NodeNG, nodes.NodeNG): merged dictionary of nodes + """ + combined_dict = itertools.chain(lhs_dict.items(), rhs_dict.items()) + # Overwrite keys which have the same string values + string_map = {key.as_string(): (key, value) for key, value in combined_dict} + # Return to dictionary + return dict(string_map.values()) + + +def _infer_map(node, context): + """Infer all values based on Dict.items""" + values = {} + for name, value in node.items: + if isinstance(name, nodes.DictUnpack): + double_starred = helpers.safe_infer(value, context) + if not double_starred: + raise exceptions.InferenceError + if not isinstance(double_starred, nodes.Dict): + raise exceptions.InferenceError(node=node, context=context) + unpack_items = _infer_map(double_starred, context) + values = _update_with_replacement(values, unpack_items) + else: + key = helpers.safe_infer(name, context=context) + value = helpers.safe_infer(value, context=context) + if any(not elem for elem in (key, value)): + raise exceptions.InferenceError(node=node, context=context) + values = _update_with_replacement(values, {key: value}) + return values + + +nodes.Dict._infer = infer_map + + +def _higher_function_scope(node): + """ Search for the first function which encloses the given + scope. This can be used for looking up in that function's + scope, in case looking up in a lower scope for a particular + name fails. + + :param node: A scope node. + :returns: + ``None``, if no parent function scope was found, + otherwise an instance of :class:`astroid.scoped_nodes.Function`, + which encloses the given node. + """ + current = node + while current.parent and not isinstance(current.parent, nodes.FunctionDef): + current = current.parent + if current and current.parent: + return current.parent + return None + + +def infer_name(self, context=None): + """infer a Name: use name lookup rules""" + frame, stmts = self.lookup(self.name) + if not stmts: + # Try to see if the name is enclosed in a nested function + # and use the higher (first function) scope for searching. + parent_function = _higher_function_scope(self.scope()) + if parent_function: + _, stmts = parent_function.lookup(self.name) + + if not stmts: + raise exceptions.NameInferenceError( + name=self.name, scope=self.scope(), context=context + ) + context = contextmod.copy_context(context) + context.lookupname = self.name + return bases._infer_stmts(stmts, context, frame) + + +# pylint: disable=no-value-for-parameter +nodes.Name._infer = decorators.raise_if_nothing_inferred( + decorators.path_wrapper(infer_name) +) +nodes.AssignName.infer_lhs = infer_name # won't work with a path wrapper + + +@decorators.raise_if_nothing_inferred +@decorators.path_wrapper +def infer_call(self, context=None): + """infer a Call node by trying to guess what the function returns""" + callcontext = contextmod.copy_context(context) + callcontext.callcontext = contextmod.CallContext( + args=self.args, keywords=self.keywords + ) + callcontext.boundnode = None + if context is not None: + callcontext.extra_context = _populate_context_lookup(self, context.clone()) + + for callee in self.func.infer(context): + if callee is util.Uninferable: + yield callee + continue + try: + if hasattr(callee, "infer_call_result"): + yield from callee.infer_call_result(caller=self, context=callcontext) + except exceptions.InferenceError: + continue + return dict(node=self, context=context) + + +nodes.Call._infer = infer_call + + +@decorators.raise_if_nothing_inferred +@decorators.path_wrapper +def infer_import(self, context=None, asname=True): + """infer an Import node: return the imported module/object""" + name = context.lookupname + if name is None: + raise exceptions.InferenceError(node=self, context=context) + + try: + if asname: + yield self.do_import_module(self.real_name(name)) + else: + yield self.do_import_module(name) + except exceptions.AstroidBuildingError as exc: + raise exceptions.InferenceError(node=self, context=context) from exc + + +nodes.Import._infer = infer_import + + +@decorators.raise_if_nothing_inferred +@decorators.path_wrapper +def infer_import_from(self, context=None, asname=True): + """infer a ImportFrom node: return the imported module/object""" + name = context.lookupname + if name is None: + raise exceptions.InferenceError(node=self, context=context) + if asname: + name = self.real_name(name) + + try: + module = self.do_import_module() + except exceptions.AstroidBuildingError as exc: + raise exceptions.InferenceError(node=self, context=context) from exc + + try: + context = contextmod.copy_context(context) + context.lookupname = name + stmts = module.getattr(name, ignore_locals=module is self.root()) + return bases._infer_stmts(stmts, context) + except exceptions.AttributeInferenceError as error: + raise exceptions.InferenceError( + error.message, target=self, attribute=name, context=context + ) from error + + +nodes.ImportFrom._infer = infer_import_from + + +def infer_attribute(self, context=None): + """infer an Attribute node by using getattr on the associated object""" + for owner in self.expr.infer(context): + if owner is util.Uninferable: + yield owner + continue + + if context and context.boundnode: + # This handles the situation where the attribute is accessed through a subclass + # of a base class and the attribute is defined at the base class's level, + # by taking in consideration a redefinition in the subclass. + if isinstance(owner, bases.Instance) and isinstance( + context.boundnode, bases.Instance + ): + try: + if helpers.is_subtype( + helpers.object_type(context.boundnode), + helpers.object_type(owner), + ): + owner = context.boundnode + except exceptions._NonDeducibleTypeHierarchy: + # Can't determine anything useful. + pass + + try: + context.boundnode = owner + yield from owner.igetattr(self.attrname, context) + context.boundnode = None + except (exceptions.AttributeInferenceError, exceptions.InferenceError): + context.boundnode = None + except AttributeError: + # XXX method / function + context.boundnode = None + return dict(node=self, context=context) + + +nodes.Attribute._infer = decorators.raise_if_nothing_inferred( + decorators.path_wrapper(infer_attribute) +) +# won't work with a path wrapper +nodes.AssignAttr.infer_lhs = decorators.raise_if_nothing_inferred(infer_attribute) + + +@decorators.raise_if_nothing_inferred +@decorators.path_wrapper +def infer_global(self, context=None): + if context.lookupname is None: + raise exceptions.InferenceError(node=self, context=context) + try: + return bases._infer_stmts(self.root().getattr(context.lookupname), context) + except exceptions.AttributeInferenceError as error: + raise exceptions.InferenceError( + error.message, target=self, attribute=context.lookupname, context=context + ) from error + + +nodes.Global._infer = infer_global + + +_SUBSCRIPT_SENTINEL = object() + + +@decorators.raise_if_nothing_inferred +def infer_subscript(self, context=None): + """Inference for subscripts + + We're understanding if the index is a Const + or a slice, passing the result of inference + to the value's `getitem` method, which should + handle each supported index type accordingly. + """ + + found_one = False + for value in self.value.infer(context): + if value is util.Uninferable: + yield util.Uninferable + return None + for index in self.slice.infer(context): + if index is util.Uninferable: + yield util.Uninferable + return None + + # Try to deduce the index value. + index_value = _SUBSCRIPT_SENTINEL + if value.__class__ == bases.Instance: + index_value = index + else: + if index.__class__ == bases.Instance: + instance_as_index = helpers.class_instance_as_index(index) + if instance_as_index: + index_value = instance_as_index + else: + index_value = index + if index_value is _SUBSCRIPT_SENTINEL: + raise exceptions.InferenceError(node=self, context=context) + + try: + assigned = value.getitem(index_value, context) + except ( + exceptions.AstroidTypeError, + exceptions.AstroidIndexError, + exceptions.AttributeInferenceError, + AttributeError, + ) as exc: + raise exceptions.InferenceError(node=self, context=context) from exc + + # Prevent inferring if the inferred subscript + # is the same as the original subscripted object. + if self is assigned or assigned is util.Uninferable: + yield util.Uninferable + return None + yield from assigned.infer(context) + found_one = True + + if found_one: + return dict(node=self, context=context) + return None + + +nodes.Subscript._infer = decorators.path_wrapper(infer_subscript) +nodes.Subscript.infer_lhs = infer_subscript + + +@decorators.raise_if_nothing_inferred +@decorators.path_wrapper +def _infer_boolop(self, context=None): + """Infer a boolean operation (and / or / not). + + The function will calculate the boolean operation + for all pairs generated through inference for each component + node. + """ + values = self.values + if self.op == "or": + predicate = operator.truth + else: + predicate = operator.not_ + + try: + values = [value.infer(context=context) for value in values] + except exceptions.InferenceError: + yield util.Uninferable + return None + + for pair in itertools.product(*values): + if any(item is util.Uninferable for item in pair): + # Can't infer the final result, just yield Uninferable. + yield util.Uninferable + continue + + bool_values = [item.bool_value() for item in pair] + if any(item is util.Uninferable for item in bool_values): + # Can't infer the final result, just yield Uninferable. + yield util.Uninferable + continue + + # Since the boolean operations are short circuited operations, + # this code yields the first value for which the predicate is True + # and if no value respected the predicate, then the last value will + # be returned (or Uninferable if there was no last value). + # This is conforming to the semantics of `and` and `or`: + # 1 and 0 -> 1 + # 0 and 1 -> 0 + # 1 or 0 -> 1 + # 0 or 1 -> 1 + value = util.Uninferable + for value, bool_value in zip(pair, bool_values): + if predicate(bool_value): + yield value + break + else: + yield value + + return dict(node=self, context=context) + + +nodes.BoolOp._infer = _infer_boolop + + +# UnaryOp, BinOp and AugAssign inferences + + +def _filter_operation_errors(self, infer_callable, context, error): + for result in infer_callable(self, context): + if isinstance(result, error): + # For the sake of .infer(), we don't care about operation + # errors, which is the job of pylint. So return something + # which shows that we can't infer the result. + yield util.Uninferable + else: + yield result + + +def _infer_unaryop(self, context=None): + """Infer what an UnaryOp should return when evaluated.""" + for operand in self.operand.infer(context): + try: + yield operand.infer_unary_op(self.op) + except TypeError as exc: + # The operand doesn't support this operation. + yield util.BadUnaryOperationMessage(operand, self.op, exc) + except AttributeError as exc: + meth = protocols.UNARY_OP_METHOD[self.op] + if meth is None: + # `not node`. Determine node's boolean + # value and negate its result, unless it is + # Uninferable, which will be returned as is. + bool_value = operand.bool_value() + if bool_value is not util.Uninferable: + yield nodes.const_factory(not bool_value) + else: + yield util.Uninferable + else: + if not isinstance(operand, (bases.Instance, nodes.ClassDef)): + # The operation was used on something which + # doesn't support it. + yield util.BadUnaryOperationMessage(operand, self.op, exc) + continue + + try: + try: + methods = dunder_lookup.lookup(operand, meth) + except exceptions.AttributeInferenceError: + yield util.BadUnaryOperationMessage(operand, self.op, exc) + continue + + meth = methods[0] + inferred = next(meth.infer(context=context)) + if inferred is util.Uninferable or not inferred.callable(): + continue + + context = contextmod.copy_context(context) + context.callcontext = contextmod.CallContext(args=[operand]) + call_results = inferred.infer_call_result(self, context=context) + result = next(call_results, None) + if result is None: + # Failed to infer, return the same type. + yield operand + else: + yield result + except exceptions.AttributeInferenceError as exc: + # The unary operation special method was not found. + yield util.BadUnaryOperationMessage(operand, self.op, exc) + except exceptions.InferenceError: + yield util.Uninferable + + +@decorators.raise_if_nothing_inferred +@decorators.path_wrapper +def infer_unaryop(self, context=None): + """Infer what an UnaryOp should return when evaluated.""" + yield from _filter_operation_errors( + self, _infer_unaryop, context, util.BadUnaryOperationMessage + ) + return dict(node=self, context=context) + + +nodes.UnaryOp._infer_unaryop = _infer_unaryop +nodes.UnaryOp._infer = infer_unaryop + + +def _is_not_implemented(const): + """Check if the given const node is NotImplemented.""" + return isinstance(const, nodes.Const) and const.value is NotImplemented + + +def _invoke_binop_inference(instance, opnode, op, other, context, method_name): + """Invoke binary operation inference on the given instance.""" + methods = dunder_lookup.lookup(instance, method_name) + context = contextmod.bind_context_to_node(context, instance) + method = methods[0] + inferred = next(method.infer(context=context)) + if inferred is util.Uninferable: + raise exceptions.InferenceError + return instance.infer_binary_op(opnode, op, other, context, inferred) + + +def _aug_op(instance, opnode, op, other, context, reverse=False): + """Get an inference callable for an augmented binary operation.""" + method_name = protocols.AUGMENTED_OP_METHOD[op] + return functools.partial( + _invoke_binop_inference, + instance=instance, + op=op, + opnode=opnode, + other=other, + context=context, + method_name=method_name, + ) + + +def _bin_op(instance, opnode, op, other, context, reverse=False): + """Get an inference callable for a normal binary operation. + + If *reverse* is True, then the reflected method will be used instead. + """ + if reverse: + method_name = protocols.REFLECTED_BIN_OP_METHOD[op] + else: + method_name = protocols.BIN_OP_METHOD[op] + return functools.partial( + _invoke_binop_inference, + instance=instance, + op=op, + opnode=opnode, + other=other, + context=context, + method_name=method_name, + ) + + +def _get_binop_contexts(context, left, right): + """Get contexts for binary operations. + + This will return two inference contexts, the first one + for x.__op__(y), the other one for y.__rop__(x), where + only the arguments are inversed. + """ + # The order is important, since the first one should be + # left.__op__(right). + for arg in (right, left): + new_context = context.clone() + new_context.callcontext = contextmod.CallContext(args=[arg]) + new_context.boundnode = None + yield new_context + + +def _same_type(type1, type2): + """Check if type1 is the same as type2.""" + return type1.qname() == type2.qname() + + +def _get_binop_flow( + left, left_type, binary_opnode, right, right_type, context, reverse_context +): + """Get the flow for binary operations. + + The rules are a bit messy: + + * if left and right have the same type, then only one + method will be called, left.__op__(right) + * if left and right are unrelated typewise, then first + left.__op__(right) is tried and if this does not exist + or returns NotImplemented, then right.__rop__(left) is tried. + * if left is a subtype of right, then only left.__op__(right) + is tried. + * if left is a supertype of right, then right.__rop__(left) + is first tried and then left.__op__(right) + """ + op = binary_opnode.op + if _same_type(left_type, right_type): + methods = [_bin_op(left, binary_opnode, op, right, context)] + elif helpers.is_subtype(left_type, right_type): + methods = [_bin_op(left, binary_opnode, op, right, context)] + elif helpers.is_supertype(left_type, right_type): + methods = [ + _bin_op(right, binary_opnode, op, left, reverse_context, reverse=True), + _bin_op(left, binary_opnode, op, right, context), + ] + else: + methods = [ + _bin_op(left, binary_opnode, op, right, context), + _bin_op(right, binary_opnode, op, left, reverse_context, reverse=True), + ] + return methods + + +def _get_aug_flow( + left, left_type, aug_opnode, right, right_type, context, reverse_context +): + """Get the flow for augmented binary operations. + + The rules are a bit messy: + + * if left and right have the same type, then left.__augop__(right) + is first tried and then left.__op__(right). + * if left and right are unrelated typewise, then + left.__augop__(right) is tried, then left.__op__(right) + is tried and then right.__rop__(left) is tried. + * if left is a subtype of right, then left.__augop__(right) + is tried and then left.__op__(right). + * if left is a supertype of right, then left.__augop__(right) + is tried, then right.__rop__(left) and then + left.__op__(right) + """ + bin_op = aug_opnode.op.strip("=") + aug_op = aug_opnode.op + if _same_type(left_type, right_type): + methods = [ + _aug_op(left, aug_opnode, aug_op, right, context), + _bin_op(left, aug_opnode, bin_op, right, context), + ] + elif helpers.is_subtype(left_type, right_type): + methods = [ + _aug_op(left, aug_opnode, aug_op, right, context), + _bin_op(left, aug_opnode, bin_op, right, context), + ] + elif helpers.is_supertype(left_type, right_type): + methods = [ + _aug_op(left, aug_opnode, aug_op, right, context), + _bin_op(right, aug_opnode, bin_op, left, reverse_context, reverse=True), + _bin_op(left, aug_opnode, bin_op, right, context), + ] + else: + methods = [ + _aug_op(left, aug_opnode, aug_op, right, context), + _bin_op(left, aug_opnode, bin_op, right, context), + _bin_op(right, aug_opnode, bin_op, left, reverse_context, reverse=True), + ] + return methods + + +def _infer_binary_operation(left, right, binary_opnode, context, flow_factory): + """Infer a binary operation between a left operand and a right operand + + This is used by both normal binary operations and augmented binary + operations, the only difference is the flow factory used. + """ + + context, reverse_context = _get_binop_contexts(context, left, right) + left_type = helpers.object_type(left) + right_type = helpers.object_type(right) + methods = flow_factory( + left, left_type, binary_opnode, right, right_type, context, reverse_context + ) + for method in methods: + try: + results = list(method()) + except AttributeError: + continue + except exceptions.AttributeInferenceError: + continue + except exceptions.InferenceError: + yield util.Uninferable + return + else: + if any(result is util.Uninferable for result in results): + yield util.Uninferable + return + + if all(map(_is_not_implemented, results)): + continue + not_implemented = sum( + 1 for result in results if _is_not_implemented(result) + ) + if not_implemented and not_implemented != len(results): + # Can't infer yet what this is. + yield util.Uninferable + return + + yield from results + return + # The operation doesn't seem to be supported so let the caller know about it + yield util.BadBinaryOperationMessage(left_type, binary_opnode.op, right_type) + + +def _infer_binop(self, context): + """Binary operation inference logic.""" + left = self.left + right = self.right + + # we use two separate contexts for evaluating lhs and rhs because + # 1. evaluating lhs may leave some undesired entries in context.path + # which may not let us infer right value of rhs + context = context or contextmod.InferenceContext() + lhs_context = contextmod.copy_context(context) + rhs_context = contextmod.copy_context(context) + lhs_iter = left.infer(context=lhs_context) + rhs_iter = right.infer(context=rhs_context) + for lhs, rhs in itertools.product(lhs_iter, rhs_iter): + if any(value is util.Uninferable for value in (rhs, lhs)): + # Don't know how to process this. + yield util.Uninferable + return + + try: + yield from _infer_binary_operation(lhs, rhs, self, context, _get_binop_flow) + except exceptions._NonDeducibleTypeHierarchy: + yield util.Uninferable + + +@decorators.yes_if_nothing_inferred +@decorators.path_wrapper +def infer_binop(self, context=None): + return _filter_operation_errors( + self, _infer_binop, context, util.BadBinaryOperationMessage + ) + + +nodes.BinOp._infer_binop = _infer_binop +nodes.BinOp._infer = infer_binop + + +def _infer_augassign(self, context=None): + """Inference logic for augmented binary operations.""" + if context is None: + context = contextmod.InferenceContext() + + rhs_context = context.clone() + + lhs_iter = self.target.infer_lhs(context=context) + rhs_iter = self.value.infer(context=rhs_context) + for lhs, rhs in itertools.product(lhs_iter, rhs_iter): + if any(value is util.Uninferable for value in (rhs, lhs)): + # Don't know how to process this. + yield util.Uninferable + return + + try: + yield from _infer_binary_operation( + left=lhs, + right=rhs, + binary_opnode=self, + context=context, + flow_factory=_get_aug_flow, + ) + except exceptions._NonDeducibleTypeHierarchy: + yield util.Uninferable + + +@decorators.raise_if_nothing_inferred +@decorators.path_wrapper +def infer_augassign(self, context=None): + return _filter_operation_errors( + self, _infer_augassign, context, util.BadBinaryOperationMessage + ) + + +nodes.AugAssign._infer_augassign = _infer_augassign +nodes.AugAssign._infer = infer_augassign + +# End of binary operation inference. + + +@decorators.raise_if_nothing_inferred +def infer_arguments(self, context=None): + name = context.lookupname + if name is None: + raise exceptions.InferenceError(node=self, context=context) + return protocols._arguments_infer_argname(self, name, context) + + +nodes.Arguments._infer = infer_arguments + + +@decorators.raise_if_nothing_inferred +@decorators.path_wrapper +def infer_assign(self, context=None): + """infer a AssignName/AssignAttr: need to inspect the RHS part of the + assign node + """ + stmt = self.statement() + if isinstance(stmt, nodes.AugAssign): + return stmt.infer(context) + + stmts = list(self.assigned_stmts(context=context)) + return bases._infer_stmts(stmts, context) + + +nodes.AssignName._infer = infer_assign +nodes.AssignAttr._infer = infer_assign + + +@decorators.raise_if_nothing_inferred +@decorators.path_wrapper +def infer_empty_node(self, context=None): + if not self.has_underlying_object(): + yield util.Uninferable + else: + try: + yield from MANAGER.infer_ast_from_something(self.object, context=context) + except exceptions.AstroidError: + yield util.Uninferable + + +nodes.EmptyNode._infer = infer_empty_node + + +@decorators.raise_if_nothing_inferred +def infer_index(self, context=None): + return self.value.infer(context) + + +nodes.Index._infer = infer_index + +# TODO: move directly into bases.Instance when the dependency hell +# will be solved. +def instance_getitem(self, index, context=None): + # Rewrap index to Const for this case + new_context = contextmod.bind_context_to_node(context, self) + if not context: + context = new_context + + # Create a new callcontext for providing index as an argument. + new_context.callcontext = contextmod.CallContext(args=[index]) + + method = next(self.igetattr("__getitem__", context=context), None) + if not isinstance(method, bases.BoundMethod): + raise exceptions.InferenceError( + "Could not find __getitem__ for {node!r}.", node=self, context=context + ) + + return next(method.infer_call_result(self, new_context)) + + +bases.Instance.getitem = instance_getitem + + +def _populate_context_lookup(call, context): + # Allows context to be saved for later + # for inference inside a function + context_lookup = {} + if context is None: + return context_lookup + for arg in call.args: + if isinstance(arg, nodes.Starred): + context_lookup[arg.value] = context + else: + context_lookup[arg] = context + keywords = call.keywords if call.keywords is not None else [] + for keyword in keywords: + context_lookup[keyword.value] = context + return context_lookup + + +@decorators.raise_if_nothing_inferred +def infer_ifexp(self, context=None): + """Support IfExp inference + + If we can't infer the truthiness of the condition, we default + to inferring both branches. Otherwise, we infer either branch + depending on the condition. + """ + both_branches = False + # We use two separate contexts for evaluating lhs and rhs because + # evaluating lhs may leave some undesired entries in context.path + # which may not let us infer right value of rhs. + + context = context or contextmod.InferenceContext() + lhs_context = contextmod.copy_context(context) + rhs_context = contextmod.copy_context(context) + try: + test = next(self.test.infer(context=context.clone())) + except exceptions.InferenceError: + both_branches = True + else: + if test is not util.Uninferable: + if test.bool_value(): + yield from self.body.infer(context=lhs_context) + else: + yield from self.orelse.infer(context=rhs_context) + else: + both_branches = True + if both_branches: + yield from self.body.infer(context=lhs_context) + yield from self.orelse.infer(context=rhs_context) + + +nodes.IfExp._infer = infer_ifexp |