# Copyright (c) 2009-2011, 2013-2014 LOGILAB S.A. (Paris, FRANCE) # Copyright (c) 2014-2020 Claudiu Popa # Copyright (c) 2014 Google, Inc. # Copyright (c) 2014 Eevee (Alex Munroe) # Copyright (c) 2015-2016 Ceridwen # Copyright (c) 2015 Dmitry Pribysh # Copyright (c) 2016 Derek Gustafson # Copyright (c) 2017-2018 Ashley Whetter # Copyright (c) 2017 Łukasz Rogalski # Copyright (c) 2017 rr- # Copyright (c) 2018 Nick Drozd # Copyright (c) 2018 Ville Skyttä # Copyright (c) 2018 Bryce Guinta # Copyright (c) 2018 HoverHell # Copyright (c) 2019 Hugo van Kemenade # Copyright (c) 2020-2021 hippo91 # Copyright (c) 2020 Vilnis Termanis # Copyright (c) 2020 Ram Rachum # Copyright (c) 2021 Pierre Sassoulas # Copyright (c) 2021 doranid # Copyright (c) 2021 Marc Mueller <30130371+cdce8p@users.noreply.github.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/main/LICENSE """this module contains a set of functions to handle python protocols for nodes where it makes sense. """ import collections import itertools import operator as operator_mod import sys from typing import Generator, Optional from astroid import arguments, bases from astroid import context as contextmod from astroid import decorators, helpers, node_classes, nodes, util from astroid.const import Context from astroid.exceptions import ( AstroidIndexError, AstroidTypeError, AttributeInferenceError, InferenceError, NoDefault, ) if sys.version_info >= (3, 8): # pylint: disable=no-name-in-module from typing import Literal else: from typing_extensions import Literal raw_building = util.lazy_import("raw_building") objects = util.lazy_import("objects") def _reflected_name(name): return "__r" + name[2:] def _augmented_name(name): return "__i" + name[2:] _CONTEXTLIB_MGR = "contextlib.contextmanager" BIN_OP_METHOD = { "+": "__add__", "-": "__sub__", "/": "__truediv__", "//": "__floordiv__", "*": "__mul__", "**": "__pow__", "%": "__mod__", "&": "__and__", "|": "__or__", "^": "__xor__", "<<": "__lshift__", ">>": "__rshift__", "@": "__matmul__", } REFLECTED_BIN_OP_METHOD = { key: _reflected_name(value) for (key, value) in BIN_OP_METHOD.items() } AUGMENTED_OP_METHOD = { key + "=": _augmented_name(value) for (key, value) in BIN_OP_METHOD.items() } UNARY_OP_METHOD = { "+": "__pos__", "-": "__neg__", "~": "__invert__", "not": None, # XXX not '__nonzero__' } _UNARY_OPERATORS = { "+": operator_mod.pos, "-": operator_mod.neg, "~": operator_mod.invert, "not": operator_mod.not_, } def _infer_unary_op(obj, op): func = _UNARY_OPERATORS[op] value = func(obj) return nodes.const_factory(value) nodes.Tuple.infer_unary_op = lambda self, op: _infer_unary_op(tuple(self.elts), op) nodes.List.infer_unary_op = lambda self, op: _infer_unary_op(self.elts, op) nodes.Set.infer_unary_op = lambda self, op: _infer_unary_op(set(self.elts), op) nodes.Const.infer_unary_op = lambda self, op: _infer_unary_op(self.value, op) nodes.Dict.infer_unary_op = lambda self, op: _infer_unary_op(dict(self.items), op) # Binary operations BIN_OP_IMPL = { "+": lambda a, b: a + b, "-": lambda a, b: a - b, "/": lambda a, b: a / b, "//": lambda a, b: a // b, "*": lambda a, b: a * b, "**": lambda a, b: a ** b, "%": lambda a, b: a % b, "&": lambda a, b: a & b, "|": lambda a, b: a | b, "^": lambda a, b: a ^ b, "<<": lambda a, b: a << b, ">>": lambda a, b: a >> b, "@": operator_mod.matmul, } for _KEY, _IMPL in list(BIN_OP_IMPL.items()): BIN_OP_IMPL[_KEY + "="] = _IMPL @decorators.yes_if_nothing_inferred def const_infer_binary_op(self, opnode, operator, other, context, _): not_implemented = nodes.Const(NotImplemented) if isinstance(other, nodes.Const): try: impl = BIN_OP_IMPL[operator] try: yield nodes.const_factory(impl(self.value, other.value)) except TypeError: # ArithmeticError is not enough: float >> float is a TypeError yield not_implemented except Exception: # pylint: disable=broad-except yield util.Uninferable except TypeError: yield not_implemented elif isinstance(self.value, str) and operator == "%": # TODO(cpopa): implement string interpolation later on. yield util.Uninferable else: yield not_implemented nodes.Const.infer_binary_op = const_infer_binary_op def _multiply_seq_by_int(self, opnode, other, context): node = self.__class__(parent=opnode) filtered_elts = ( helpers.safe_infer(elt, context) or util.Uninferable for elt in self.elts if elt is not util.Uninferable ) node.elts = list(filtered_elts) * other.value return node def _filter_uninferable_nodes(elts, context): for elt in elts: if elt is util.Uninferable: yield nodes.Unknown() else: for inferred in elt.infer(context): if inferred is not util.Uninferable: yield inferred else: yield nodes.Unknown() @decorators.yes_if_nothing_inferred def tl_infer_binary_op(self, opnode, operator, other, context, method): not_implemented = nodes.Const(NotImplemented) if isinstance(other, self.__class__) and operator == "+": node = self.__class__(parent=opnode) node.elts = list( itertools.chain( _filter_uninferable_nodes(self.elts, context), _filter_uninferable_nodes(other.elts, context), ) ) yield node elif isinstance(other, nodes.Const) and operator == "*": if not isinstance(other.value, int): yield not_implemented return yield _multiply_seq_by_int(self, opnode, other, context) elif isinstance(other, bases.Instance) and operator == "*": # Verify if the instance supports __index__. as_index = helpers.class_instance_as_index(other) if not as_index: yield util.Uninferable else: yield _multiply_seq_by_int(self, opnode, as_index, context) else: yield not_implemented nodes.Tuple.infer_binary_op = tl_infer_binary_op nodes.List.infer_binary_op = tl_infer_binary_op @decorators.yes_if_nothing_inferred def instance_class_infer_binary_op(self, opnode, operator, other, context, method): return method.infer_call_result(self, context) bases.Instance.infer_binary_op = instance_class_infer_binary_op nodes.ClassDef.infer_binary_op = instance_class_infer_binary_op # assignment ################################################################## """the assigned_stmts method is responsible to return the assigned statement (e.g. not inferred) according to the assignment type. The `assign_path` argument is used to record the lhs path of the original node. For instance if we want assigned statements for 'c' in 'a, (b,c)', assign_path will be [1, 1] once arrived to the Assign node. The `context` argument is the current inference context which should be given to any intermediary inference necessary. """ def _resolve_looppart(parts, assign_path, context): """recursive function to resolve multiple assignments on loops""" assign_path = assign_path[:] index = assign_path.pop(0) for part in parts: if part is util.Uninferable: continue if not hasattr(part, "itered"): continue try: itered = part.itered() except TypeError: continue for stmt in itered: index_node = nodes.Const(index) try: assigned = stmt.getitem(index_node, context) except (AttributeError, AstroidTypeError, AstroidIndexError): continue if not assign_path: # we achieved to resolved the assignment path, # don't infer the last part yield assigned elif assigned is util.Uninferable: break else: # we are not yet on the last part of the path # search on each possibly inferred value try: yield from _resolve_looppart( assigned.infer(context), assign_path, context ) except InferenceError: break @decorators.raise_if_nothing_inferred def for_assigned_stmts(self, node=None, context=None, assign_path=None): if isinstance(self, nodes.AsyncFor) or getattr(self, "is_async", False): # Skip inferring of async code for now return dict(node=self, unknown=node, assign_path=assign_path, context=context) if assign_path is None: for lst in self.iter.infer(context): if isinstance(lst, (nodes.Tuple, nodes.List)): yield from lst.elts else: yield from _resolve_looppart(self.iter.infer(context), assign_path, context) return dict(node=self, unknown=node, assign_path=assign_path, context=context) nodes.For.assigned_stmts = for_assigned_stmts nodes.Comprehension.assigned_stmts = for_assigned_stmts def sequence_assigned_stmts(self, node=None, context=None, assign_path=None): if assign_path is None: assign_path = [] try: index = self.elts.index(node) except ValueError as exc: raise InferenceError( "Tried to retrieve a node {node!r} which does not exist", node=self, assign_path=assign_path, context=context, ) from exc assign_path.insert(0, index) return self.parent.assigned_stmts( node=self, context=context, assign_path=assign_path ) nodes.Tuple.assigned_stmts = sequence_assigned_stmts nodes.List.assigned_stmts = sequence_assigned_stmts def assend_assigned_stmts(self, node=None, context=None, assign_path=None): return self.parent.assigned_stmts(node=self, context=context) nodes.AssignName.assigned_stmts = assend_assigned_stmts nodes.AssignAttr.assigned_stmts = assend_assigned_stmts def _arguments_infer_argname(self, name, context): # arguments information may be missing, in which case we can't do anything # more if not (self.arguments or self.vararg or self.kwarg): yield util.Uninferable return functype = self.parent.type # first argument of instance/class method if ( self.arguments and getattr(self.arguments[0], "name", None) == name and functype != "staticmethod" ): cls = self.parent.parent.scope() is_metaclass = isinstance(cls, nodes.ClassDef) and cls.type == "metaclass" # If this is a metaclass, then the first argument will always # be the class, not an instance. if context.boundnode and isinstance(context.boundnode, bases.Instance): cls = context.boundnode._proxied if is_metaclass or functype == "classmethod": yield cls return if functype == "method": yield cls.instantiate_class() return if context and context.callcontext: call_site = arguments.CallSite(context.callcontext, context.extra_context) yield from call_site.infer_argument(self.parent, name, context) return if name == self.vararg: vararg = nodes.const_factory(()) vararg.parent = self if not self.arguments and self.parent.name == "__init__": cls = self.parent.parent.scope() vararg.elts = [cls.instantiate_class()] yield vararg return if name == self.kwarg: kwarg = nodes.const_factory({}) kwarg.parent = self yield kwarg return # if there is a default value, yield it. And then yield Uninferable to reflect # we can't guess given argument value try: context = contextmod.copy_context(context) yield from self.default_value(name).infer(context) yield util.Uninferable except NoDefault: yield util.Uninferable def arguments_assigned_stmts(self, node=None, context=None, assign_path=None): if context.callcontext: # reset call context/name callcontext = context.callcontext context = contextmod.copy_context(context) context.callcontext = None args = arguments.CallSite(callcontext, context=context) return args.infer_argument(self.parent, node.name, context) return _arguments_infer_argname(self, node.name, context) nodes.Arguments.assigned_stmts = arguments_assigned_stmts @decorators.raise_if_nothing_inferred def assign_assigned_stmts(self, node=None, context=None, assign_path=None): if not assign_path: yield self.value return None yield from _resolve_assignment_parts( self.value.infer(context), assign_path, context ) return dict(node=self, unknown=node, assign_path=assign_path, context=context) def assign_annassigned_stmts(self, node=None, context=None, assign_path=None): for inferred in assign_assigned_stmts(self, node, context, assign_path): if inferred is None: yield util.Uninferable else: yield inferred nodes.Assign.assigned_stmts = assign_assigned_stmts nodes.AnnAssign.assigned_stmts = assign_annassigned_stmts nodes.AugAssign.assigned_stmts = assign_assigned_stmts def _resolve_assignment_parts(parts, assign_path, context): """recursive function to resolve multiple assignments""" assign_path = assign_path[:] index = assign_path.pop(0) for part in parts: assigned = None if isinstance(part, nodes.Dict): # A dictionary in an iterating context try: assigned, _ = part.items[index] except IndexError: return elif hasattr(part, "getitem"): index_node = nodes.Const(index) try: assigned = part.getitem(index_node, context) except (AstroidTypeError, AstroidIndexError): return if not assigned: return if not assign_path: # we achieved to resolved the assignment path, don't infer the # last part yield assigned elif assigned is util.Uninferable: return else: # we are not yet on the last part of the path search on each # possibly inferred value try: yield from _resolve_assignment_parts( assigned.infer(context), assign_path, context ) except InferenceError: return @decorators.raise_if_nothing_inferred def excepthandler_assigned_stmts(self, node=None, context=None, assign_path=None): for assigned in node_classes.unpack_infer(self.type): if isinstance(assigned, nodes.ClassDef): assigned = objects.ExceptionInstance(assigned) yield assigned return dict(node=self, unknown=node, assign_path=assign_path, context=context) nodes.ExceptHandler.assigned_stmts = excepthandler_assigned_stmts def _infer_context_manager(self, mgr, context): try: inferred = next(mgr.infer(context=context)) except StopIteration as e: raise InferenceError(node=mgr) from e if isinstance(inferred, bases.Generator): # Check if it is decorated with contextlib.contextmanager. func = inferred.parent if not func.decorators: raise InferenceError( "No decorators found on inferred generator %s", node=func ) for decorator_node in func.decorators.nodes: decorator = next(decorator_node.infer(context=context), None) if isinstance(decorator, nodes.FunctionDef): if decorator.qname() == _CONTEXTLIB_MGR: break else: # It doesn't interest us. raise InferenceError(node=func) try: yield next(inferred.infer_yield_types()) except StopIteration as e: raise InferenceError(node=func) from e elif isinstance(inferred, bases.Instance): try: enter = next(inferred.igetattr("__enter__", context=context)) except (InferenceError, AttributeInferenceError, StopIteration) as exc: raise InferenceError(node=inferred) from exc if not isinstance(enter, bases.BoundMethod): raise InferenceError(node=enter) yield from enter.infer_call_result(self, context) else: raise InferenceError(node=mgr) @decorators.raise_if_nothing_inferred def with_assigned_stmts(self, node=None, context=None, assign_path=None): """Infer names and other nodes from a *with* statement. This enables only inference for name binding in a *with* statement. For instance, in the following code, inferring `func` will return the `ContextManager` class, not whatever ``__enter__`` returns. We are doing this intentionally, because we consider that the context manager result is whatever __enter__ returns and what it is binded using the ``as`` keyword. class ContextManager(object): def __enter__(self): return 42 with ContextManager() as f: pass # ContextManager().infer() will return ContextManager # f.infer() will return 42. Arguments: self: nodes.With node: The target of the assignment, `as (a, b)` in `with foo as (a, b)`. context: Inference context used for caching already inferred objects assign_path: A list of indices, where each index specifies what item to fetch from the inference results. """ try: mgr = next(mgr for (mgr, vars) in self.items if vars == node) except StopIteration: return None if assign_path is None: yield from _infer_context_manager(self, mgr, context) else: for result in _infer_context_manager(self, mgr, context): # Walk the assign_path and get the item at the final index. obj = result for index in assign_path: if not hasattr(obj, "elts"): raise InferenceError( "Wrong type ({targets!r}) for {node!r} assignment", node=self, targets=node, assign_path=assign_path, context=context, ) try: obj = obj.elts[index] except IndexError as exc: raise InferenceError( "Tried to infer a nonexistent target with index {index} " "in {node!r}.", node=self, targets=node, assign_path=assign_path, context=context, ) from exc except TypeError as exc: raise InferenceError( "Tried to unpack a non-iterable value " "in {node!r}.", node=self, targets=node, assign_path=assign_path, context=context, ) from exc yield obj return dict(node=self, unknown=node, assign_path=assign_path, context=context) nodes.With.assigned_stmts = with_assigned_stmts @decorators.raise_if_nothing_inferred def named_expr_assigned_stmts(self, node, context=None, assign_path=None): """Infer names and other nodes from an assignment expression""" if self.target == node: yield from self.value.infer(context=context) else: raise InferenceError( "Cannot infer NamedExpr node {node!r}", node=self, assign_path=assign_path, context=context, ) nodes.NamedExpr.assigned_stmts = named_expr_assigned_stmts @decorators.yes_if_nothing_inferred def starred_assigned_stmts(self, node=None, context=None, assign_path=None): """ Arguments: self: nodes.Starred node: a node related to the current underlying Node. context: Inference context used for caching already inferred objects assign_path: A list of indices, where each index specifies what item to fetch from the inference results. """ # pylint: disable=too-many-locals,too-many-statements def _determine_starred_iteration_lookups(starred, target, lookups): # Determine the lookups for the rhs of the iteration itered = target.itered() for index, element in enumerate(itered): if ( isinstance(element, nodes.Starred) and element.value.name == starred.value.name ): lookups.append((index, len(itered))) break if isinstance(element, nodes.Tuple): lookups.append((index, len(element.itered()))) _determine_starred_iteration_lookups(starred, element, lookups) stmt = self.statement() if not isinstance(stmt, (nodes.Assign, nodes.For)): raise InferenceError( "Statement {stmt!r} enclosing {node!r} " "must be an Assign or For node.", node=self, stmt=stmt, unknown=node, context=context, ) if context is None: context = contextmod.InferenceContext() if isinstance(stmt, nodes.Assign): value = stmt.value lhs = stmt.targets[0] if sum(1 for _ in lhs.nodes_of_class(nodes.Starred)) > 1: raise InferenceError( "Too many starred arguments in the " " assignment targets {lhs!r}.", node=self, targets=lhs, unknown=node, context=context, ) try: rhs = next(value.infer(context)) except (InferenceError, StopIteration): yield util.Uninferable return if rhs is util.Uninferable or not hasattr(rhs, "itered"): yield util.Uninferable return try: elts = collections.deque(rhs.itered()) except TypeError: yield util.Uninferable return # Unpack iteratively the values from the rhs of the assignment, # until the find the starred node. What will remain will # be the list of values which the Starred node will represent # This is done in two steps, from left to right to remove # anything before the starred node and from right to left # to remove anything after the starred node. for index, left_node in enumerate(lhs.elts): if not isinstance(left_node, nodes.Starred): if not elts: break elts.popleft() continue lhs_elts = collections.deque(reversed(lhs.elts[index:])) for right_node in lhs_elts: if not isinstance(right_node, nodes.Starred): if not elts: break elts.pop() continue # We're done unpacking. packed = nodes.List( ctx=Context.Store, parent=self, lineno=lhs.lineno, col_offset=lhs.col_offset, ) packed.postinit(elts=list(elts)) yield packed break if isinstance(stmt, nodes.For): try: inferred_iterable = next(stmt.iter.infer(context=context)) except (InferenceError, StopIteration): yield util.Uninferable return if inferred_iterable is util.Uninferable or not hasattr( inferred_iterable, "itered" ): yield util.Uninferable return try: itered = inferred_iterable.itered() except TypeError: yield util.Uninferable return target = stmt.target if not isinstance(target, nodes.Tuple): raise InferenceError( "Could not make sense of this, the target must be a tuple", context=context, ) lookups = [] _determine_starred_iteration_lookups(self, target, lookups) if not lookups: raise InferenceError( "Could not make sense of this, needs at least a lookup", context=context ) # Make the last lookup a slice, since that what we want for a Starred node last_element_index, last_element_length = lookups[-1] is_starred_last = last_element_index == (last_element_length - 1) lookup_slice = slice( last_element_index, None if is_starred_last else (last_element_length - last_element_index), ) lookups[-1] = lookup_slice for element in itered: # We probably want to infer the potential values *for each* element in an # iterable, but we can't infer a list of all values, when only a list of # step values are expected: # # for a, *b in [...]: # b # # *b* should now point to just the elements at that particular iteration step, # which astroid can't know about. found_element = None for lookup in lookups: if not hasattr(element, "itered"): break if not isinstance(lookup, slice): # Grab just the index, not the whole length lookup = lookup[0] try: itered_inner_element = element.itered() element = itered_inner_element[lookup] except IndexError: break except TypeError: # Most likely the itered() call failed, cannot make sense of this yield util.Uninferable return else: found_element = element unpacked = nodes.List( ctx=Context.Store, parent=self, lineno=self.lineno, col_offset=self.col_offset, ) unpacked.postinit(elts=found_element or []) yield unpacked return yield util.Uninferable nodes.Starred.assigned_stmts = starred_assigned_stmts @decorators.yes_if_nothing_inferred def match_mapping_assigned_stmts( self: nodes.MatchMapping, node: nodes.AssignName, context: Optional[contextmod.InferenceContext] = None, assign_path: Literal[None] = None, ) -> Generator[nodes.NodeNG, None, None]: """Return empty generator (return -> raises StopIteration) so inferred value is Uninferable. """ return yield # pylint: disable=unreachable nodes.MatchMapping.assigned_stmts = match_mapping_assigned_stmts @decorators.yes_if_nothing_inferred def match_star_assigned_stmts( self: nodes.MatchStar, node: nodes.AssignName, context: Optional[contextmod.InferenceContext] = None, assign_path: Literal[None] = None, ) -> Generator[nodes.NodeNG, None, None]: """Return empty generator (return -> raises StopIteration) so inferred value is Uninferable. """ return yield # pylint: disable=unreachable nodes.MatchStar.assigned_stmts = match_star_assigned_stmts @decorators.yes_if_nothing_inferred def match_as_assigned_stmts( self: nodes.MatchAs, node: nodes.AssignName, context: Optional[contextmod.InferenceContext] = None, assign_path: Literal[None] = None, ) -> Generator[nodes.NodeNG, None, None]: """Infer MatchAs as the Match subject if it's the only MatchCase pattern else raise StopIteration to yield Uninferable. """ if ( isinstance(self.parent, nodes.MatchCase) and isinstance(self.parent.parent, nodes.Match) and self.pattern is None ): yield self.parent.parent.subject nodes.MatchAs.assigned_stmts = match_as_assigned_stmts