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# Copyright (c) 2015-2018 Claudiu Popa <pcmanticore@gmail.com>
# Copyright (c) 2015-2016 Ceridwen <ceridwenv@gmail.com>
# Copyright (c) 2018 Bryce Guinta <bryce.paul.guinta@gmail.com>
# Copyright (c) 2018 Nick Drozd <nicholasdrozd@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
import warnings
from itertools import islice
import importlib
import lazy_object_proxy
def lazy_descriptor(obj):
class DescriptorProxy(lazy_object_proxy.Proxy):
def __get__(self, instance, owner=None):
return self.__class__.__get__(self, instance)
return DescriptorProxy(obj)
def lazy_import(module_name):
return lazy_object_proxy.Proxy(
lambda: importlib.import_module("." + module_name, "astroid")
)
@object.__new__
class Uninferable:
"""Special inference object, which is returned when inference fails."""
def __repr__(self):
return "Uninferable"
__str__ = __repr__
def __getattribute__(self, name):
if name == "next":
raise AttributeError("next method should not be called")
if name.startswith("__") and name.endswith("__"):
return object.__getattribute__(self, name)
if name == "accept":
return object.__getattribute__(self, name)
return self
def __call__(self, *args, **kwargs):
return self
def __bool__(self):
return False
__nonzero__ = __bool__
def accept(self, visitor):
func = getattr(visitor, "visit_uninferable")
return func(self)
class BadOperationMessage:
"""Object which describes a TypeError occurred somewhere in the inference chain
This is not an exception, but a container object which holds the types and
the error which occurred.
"""
class BadUnaryOperationMessage(BadOperationMessage):
"""Object which describes operational failures on UnaryOps."""
def __init__(self, operand, op, error):
self.operand = operand
self.op = op
self.error = error
@property
def _object_type_helper(self):
helpers = lazy_import("helpers")
return helpers.object_type
def _object_type(self, obj):
# pylint: disable=not-callable; can't infer lazy_import
objtype = self._object_type_helper(obj)
if objtype is Uninferable:
return None
return objtype
def __str__(self):
if hasattr(self.operand, "name"):
operand_type = self.operand.name
else:
object_type = self._object_type(self.operand)
if hasattr(object_type, "name"):
operand_type = object_type.name
else:
# Just fallback to as_string
operand_type = object_type.as_string()
msg = "bad operand type for unary {}: {}"
return msg.format(self.op, operand_type)
class BadBinaryOperationMessage(BadOperationMessage):
"""Object which describes type errors for BinOps."""
def __init__(self, left_type, op, right_type):
self.left_type = left_type
self.right_type = right_type
self.op = op
def __str__(self):
msg = "unsupported operand type(s) for {}: {!r} and {!r}"
return msg.format(self.op, self.left_type.name, self.right_type.name)
def _instancecheck(cls, other):
wrapped = cls.__wrapped__
other_cls = other.__class__
is_instance_of = wrapped is other_cls or issubclass(other_cls, wrapped)
warnings.warn(
"%r is deprecated and slated for removal in astroid "
"2.0, use %r instead" % (cls.__class__.__name__, wrapped.__name__),
PendingDeprecationWarning,
stacklevel=2,
)
return is_instance_of
def proxy_alias(alias_name, node_type):
"""Get a Proxy from the given name to the given node type."""
proxy = type(
alias_name,
(lazy_object_proxy.Proxy,),
{
"__class__": object.__dict__["__class__"],
"__instancecheck__": _instancecheck,
},
)
return proxy(lambda: node_type)
def limit_inference(iterator, size):
"""Limit inference amount.
Limit inference amount to help with performance issues with
exponentially exploding possible results.
:param iterator: Inference generator to limit
:type iterator: Iterator(NodeNG)
:param size: Maximum mount of nodes yielded plus an
Uninferable at the end if limit reached
:type size: int
:yields: A possibly modified generator
:rtype param: Iterable
"""
yield from islice(iterator, size)
has_more = next(iterator, False)
if has_more is not False:
yield Uninferable
return
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