# -*- coding: utf-8 -*- # Copyright (c) 2009-2011, 2013-2014 LOGILAB S.A. (Paris, FRANCE) # Copyright (c) 2014-2018 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 Bryce Guinta # Copyright (c) 2018 Nick Drozd # Copyright (c) 2018 HoverHell # 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 python protocols for nodes where it makes sense. """ import collections import operator as operator_mod import sys import itertools from astroid import Store from astroid import arguments from astroid import bases from astroid import context as contextmod from astroid import exceptions from astroid import decorators from astroid import node_classes from astroid import helpers from astroid import nodes from astroid import util 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, } if sys.version_info >= (3, 5): # MatMult is available since Python 3.5+. BIN_OP_IMPL["@"] = 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, exceptions.AstroidTypeError, exceptions.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 exceptions.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 exceptions.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.args or self.vararg or self.kwarg): yield util.Uninferable return # first argument of instance/class method if self.args and getattr(self.args[0], "name", None) == name: functype = self.parent.type 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 is_metaclass or functype == "classmethod": yield cls return if functype == "method": yield bases.Instance(cls) 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 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 exceptions.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) 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 (exceptions.AstroidTypeError, exceptions.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 exceptions.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): inferred = next(mgr.infer(context=context)) if isinstance(inferred, bases.Generator): # Check if it is decorated with contextlib.contextmanager. func = inferred.parent if not func.decorators: raise exceptions.InferenceError( "No decorators found on inferred generator %s", node=func ) for decorator_node in func.decorators.nodes: decorator = next(decorator_node.infer(context)) if isinstance(decorator, nodes.FunctionDef): if decorator.qname() == _CONTEXTLIB_MGR: break else: # It doesn't interest us. raise exceptions.InferenceError(node=func) # Get the first yield point. If it has multiple yields, # then a RuntimeError will be raised. possible_yield_points = func.nodes_of_class(nodes.Yield) # Ignore yields in nested functions yield_point = next( (node for node in possible_yield_points if node.scope() == func), None ) if yield_point: if not yield_point.value: const = nodes.Const(None) const.parent = yield_point const.lineno = yield_point.lineno yield const else: yield from yield_point.value.infer(context=context) elif isinstance(inferred, bases.Instance): try: enter = next(inferred.igetattr("__enter__", context=context)) except (exceptions.InferenceError, exceptions.AttributeInferenceError): raise exceptions.InferenceError(node=inferred) if not isinstance(enter, bases.BoundMethod): raise exceptions.InferenceError(node=enter) if not context.callcontext: context.callcontext = contextmod.CallContext(args=[inferred]) yield from enter.infer_call_result(self, context) else: raise exceptions.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 exceptions.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 exceptions.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 exceptions.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.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-branches,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 exceptions.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 exceptions.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 exceptions.InferenceError: 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 packed = nodes.List( ctx=Store, parent=self, lineno=lhs.lineno, col_offset=lhs.col_offset ) packed.postinit(elts=elts) yield packed break if isinstance(stmt, nodes.For): try: inferred_iterable = next(stmt.iter.infer(context=context)) except exceptions.InferenceError: 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 exceptions.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 exceptions.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=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