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# -*- coding: utf-8 -*-
# Copyright (c) 2017-2018 Claudiu Popa <pcmanticore@gmail.com>
# Copyright (c) 2017 Łukasz Rogalski <rogalski.91@gmail.com>
# Copyright (c) 2017 David Euresti <github@euresti.com>
# Copyright (c) 2018 Bryce Guinta <bryce.paul.guinta@gmail.com>
"""Astroid hooks for typing.py support."""
import typing
from astroid import (
MANAGER,
UseInferenceDefault,
extract_node,
inference_tip,
nodes,
InferenceError,
)
TYPING_NAMEDTUPLE_BASENAMES = {"NamedTuple", "typing.NamedTuple"}
TYPING_TYPEVARS = {"TypeVar", "NewType"}
TYPING_TYPEVARS_QUALIFIED = {"typing.TypeVar", "typing.NewType"}
TYPING_TYPE_TEMPLATE = """
class Meta(type):
def __getitem__(self, item):
return self
@property
def __args__(self):
return ()
class {0}(metaclass=Meta):
pass
"""
TYPING_MEMBERS = set(typing.__all__)
def looks_like_typing_typevar_or_newtype(node):
func = node.func
if isinstance(func, nodes.Attribute):
return func.attrname in TYPING_TYPEVARS
if isinstance(func, nodes.Name):
return func.name in TYPING_TYPEVARS
return False
def infer_typing_typevar_or_newtype(node, context=None):
"""Infer a typing.TypeVar(...) or typing.NewType(...) call"""
try:
func = next(node.func.infer(context=context))
except InferenceError as exc:
raise UseInferenceDefault from exc
if func.qname() not in TYPING_TYPEVARS_QUALIFIED:
raise UseInferenceDefault
if not node.args:
raise UseInferenceDefault
typename = node.args[0].as_string().strip("'")
node = extract_node(TYPING_TYPE_TEMPLATE.format(typename))
return node.infer(context=context)
def _looks_like_typing_subscript(node):
"""Try to figure out if a Subscript node *might* be a typing-related subscript"""
if isinstance(node, nodes.Name):
return node.name in TYPING_MEMBERS
elif isinstance(node, nodes.Attribute):
return node.attrname in TYPING_MEMBERS
elif isinstance(node, nodes.Subscript):
return _looks_like_typing_subscript(node.value)
return False
def infer_typing_attr(node, context=None):
"""Infer a typing.X[...] subscript"""
try:
value = next(node.value.infer())
except InferenceError as exc:
raise UseInferenceDefault from exc
if not value.qname().startswith("typing."):
raise UseInferenceDefault
node = extract_node(TYPING_TYPE_TEMPLATE.format(value.qname().split(".")[-1]))
return node.infer(context=context)
MANAGER.register_transform(
nodes.Call,
inference_tip(infer_typing_typevar_or_newtype),
looks_like_typing_typevar_or_newtype,
)
MANAGER.register_transform(
nodes.Subscript, inference_tip(infer_typing_attr), _looks_like_typing_subscript
)
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