# Copyright (c) 2009-2011, 2013-2014 LOGILAB S.A. (Paris, FRANCE) # Copyright (c) 2014-2016 Claudiu Popa # Copyright (c) 2014 Google, Inc. # Copyright (c) 2015-2016 Cara Vinson # 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 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) elts = [] filtered_elts = (elt for elt in self.elts if elt is not util.Uninferable) for elt in filtered_elts: infered = helpers.safe_infer(elt, context) if infered is None: infered = util.Uninferable elts.append(infered) node.elts = 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) elts = list(_filter_uninferable_nodes(self.elts, context)) elts += list(_filter_uninferable_nodes(other.elts, context)) node.elts = elts 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 `asspath` 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)', asspath 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, asspath, context): """recursive function to resolve multiple assignments on loops""" asspath = asspath[:] index = asspath.pop(0) for part in parts: if part is util.Uninferable: continue # XXX handle __iter__ and log potentially detected errors if not hasattr(part, 'itered'): continue try: itered = part.itered() except TypeError: continue # XXX log error 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 asspath: # 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), asspath, context) except exceptions.InferenceError: break @decorators.raise_if_nothing_inferred def for_assigned_stmts(self, node=None, context=None, asspath=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=asspath, context=context) if asspath 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), asspath, context) # Explicit StopIteration to return error information, see comment # in raise_if_nothing_inferred. return dict(node=self, unknown=node, assign_path=asspath, 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, asspath=None): if asspath is None: asspath = [] 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=asspath, context=context) from exc asspath.insert(0, index) return self.parent.assigned_stmts(node=self, context=context, asspath=asspath) nodes.Tuple.assigned_stmts = sequence_assigned_stmts nodes.List.assigned_stmts = sequence_assigned_stmts def assend_assigned_stmts(self, node=None, context=None, asspath=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(self.parent.parent.frame()) return if context and context.callcontext: call_site = arguments.CallSite(context.callcontext) for value in call_site.infer_argument(self.parent, name, context): yield value 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, asspath=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, asspath=None): if not asspath: yield self.value return None yield from _resolve_asspart(self.value.infer(context), asspath, context) # Explicit StopIteration to return error information, see comment # in raise_if_nothing_inferred. return dict(node=self, unknown=node, assign_path=asspath, context=context) def assign_annassigned_stmts(self, node=None, context=None, asspath=None): for inferred in assign_assigned_stmts(self, node, context, asspath): 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_asspart(parts, asspath, context): """recursive function to resolve multiple assignments""" asspath = asspath[:] index = asspath.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 KeyError: return elif hasattr(part, 'getitem'): index_node = nodes.Const(index) try: assigned = part.getitem(index_node, context) # XXX raise a specific exception to avoid potential hiding of # unexpected exception ? except (exceptions.AstroidTypeError, exceptions.AstroidIndexError): return if not assigned: return if not asspath: # 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_asspart(assigned.infer(context), asspath, context) except exceptions.InferenceError: return @decorators.raise_if_nothing_inferred def excepthandler_assigned_stmts(self, node=None, context=None, asspath=None): for assigned in node_classes.unpack_infer(self.type): if isinstance(assigned, nodes.ClassDef): assigned = objects.ExceptionInstance(assigned) yield assigned # Explicit StopIteration to return error information, see comment # in raise_if_nothing_inferred. return dict(node=self, unknown=node, assign_path=asspath, 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, exceptions.InferenceError): return if isinstance(inferred, bases.Generator): # Check if it is decorated with contextlib.contextmanager. func = inferred.parent if not func.decorators: return for decorator_node in func.decorators.nodes: try: decorator = next(decorator_node.infer(context)) except StopIteration: return if isinstance(decorator, nodes.FunctionDef): if decorator.qname() == _CONTEXTLIB_MGR: break else: # It doesn't interest us. return # 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 (StopIteration, exceptions.InferenceError, exceptions.AttributeInferenceError): return if not isinstance(enter, bases.BoundMethod): return if not context.callcontext: context.callcontext = contextmod.CallContext(args=[inferred]) for result in enter.infer_call_result(self, context): yield result @decorators.raise_if_nothing_inferred def with_assigned_stmts(self, node=None, context=None, asspath=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: TODO asspath: TODO """ try: mgr = next(mgr for (mgr, vars) in self.items if vars == node) except StopIteration: return None if asspath is None: for result in _infer_context_manager(self, mgr, context): yield result else: for result in _infer_context_manager(self, mgr, context): # Walk the asspath and get the item at the final index. obj = result for index in asspath: if not hasattr(obj, 'elts'): raise exceptions.InferenceError( 'Wrong type ({targets!r}) for {node!r} assignment', node=self, targets=node, assign_path=asspath, 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=asspath, context=context) from exc except TypeError as exc: raise exceptions.InferenceError( 'Tried to unpack an non-iterable value ' 'in {node!r}.', node=self, targets=node, assign_path=asspath, context=context) from exc yield obj # Explicit StopIteration to return error information, see comment # in raise_if_nothing_inferred. return dict(node=self, unknown=node, assign_path=asspath, context=context) nodes.With.assigned_stmts = with_assigned_stmts @decorators.yes_if_nothing_inferred def starred_assigned_stmts(self, node=None, context=None, asspath=None): """ Arguments: self: nodes.Starred node: TODO context: TODO asspath: TODO """ 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 isinstance(stmt, nodes.Assign): value = stmt.value lhs = stmt.targets[0] if sum(1 for node 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) if context is None: context = contextmod.InferenceContext() try: rhs = next(value.infer(context)) except StopIteration: return except exceptions.InferenceError: yield util.Uninferable return if rhs is util.Uninferable or not hasattr(rhs, 'elts'): # Not interested in inferred values without elts. yield util.Uninferable return elts = collections.deque(rhs.elts[:]) if len(lhs.elts) > len(rhs.elts): raise exceptions.InferenceError('More targets, {targets!r}, than ' 'values to unpack, {values!r}.', node=self, targets=lhs, values=rhs, unknown=node, context=context) # 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): elts.popleft() continue lhs_elts = collections.deque(reversed(lhs.elts[index:])) for right_node in lhs_elts: if not isinstance(right_node, nodes.Starred): elts.pop() continue # We're done packed = nodes.List() packed.elts = elts packed.parent = self yield packed break nodes.Starred.assigned_stmts = starred_assigned_stmts