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# 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
# Copyright (c) https://github.com/PyCQA/astroid/blob/main/CONTRIBUTORS.txt
from __future__ import annotations
from astroid.brain.helpers import register_module_extender
from astroid.builder import extract_node, parse
from astroid.const import PY39_PLUS
from astroid.context import InferenceContext
from astroid.exceptions import AttributeInferenceError
from astroid.manager import AstroidManager
from astroid.nodes.scoped_nodes import ClassDef
def _collections_transform():
return parse(
"""
class defaultdict(dict):
default_factory = None
def __missing__(self, key): pass
def __getitem__(self, key): return default_factory
"""
+ _deque_mock()
+ _ordered_dict_mock()
)
def _deque_mock():
base_deque_class = """
class deque(object):
maxlen = 0
def __init__(self, iterable=None, maxlen=None):
self.iterable = iterable or []
def append(self, x): pass
def appendleft(self, x): pass
def clear(self): pass
def count(self, x): return 0
def extend(self, iterable): pass
def extendleft(self, iterable): pass
def pop(self): return self.iterable[0]
def popleft(self): return self.iterable[0]
def remove(self, value): pass
def reverse(self): return reversed(self.iterable)
def rotate(self, n=1): return self
def __iter__(self): return self
def __reversed__(self): return self.iterable[::-1]
def __getitem__(self, index): return self.iterable[index]
def __setitem__(self, index, value): pass
def __delitem__(self, index): pass
def __bool__(self): return bool(self.iterable)
def __nonzero__(self): return bool(self.iterable)
def __contains__(self, o): return o in self.iterable
def __len__(self): return len(self.iterable)
def __copy__(self): return deque(self.iterable)
def copy(self): return deque(self.iterable)
def index(self, x, start=0, end=0): return 0
def insert(self, i, x): pass
def __add__(self, other): pass
def __iadd__(self, other): pass
def __mul__(self, other): pass
def __imul__(self, other): pass
def __rmul__(self, other): pass"""
if PY39_PLUS:
base_deque_class += """
@classmethod
def __class_getitem__(self, item): return cls"""
return base_deque_class
def _ordered_dict_mock():
base_ordered_dict_class = """
class OrderedDict(dict):
def __reversed__(self): return self[::-1]
def move_to_end(self, key, last=False): pass"""
if PY39_PLUS:
base_ordered_dict_class += """
@classmethod
def __class_getitem__(cls, item): return cls"""
return base_ordered_dict_class
register_module_extender(AstroidManager(), "collections", _collections_transform)
def _looks_like_subscriptable(node: ClassDef) -> bool:
"""
Returns True if the node corresponds to a ClassDef of the Collections.abc module that
supports subscripting
:param node: ClassDef node
"""
if node.qname().startswith("_collections") or node.qname().startswith(
"collections"
):
try:
node.getattr("__class_getitem__")
return True
except AttributeInferenceError:
pass
return False
CLASS_GET_ITEM_TEMPLATE = """
@classmethod
def __class_getitem__(cls, item):
return cls
"""
def easy_class_getitem_inference(node, context: InferenceContext | None = None):
# Here __class_getitem__ exists but is quite a mess to infer thus
# put an easy inference tip
func_to_add = extract_node(CLASS_GET_ITEM_TEMPLATE)
node.locals["__class_getitem__"] = [func_to_add]
if PY39_PLUS:
# Starting with Python39 some objects of the collection module are subscriptable
# thanks to the __class_getitem__ method but the way it is implemented in
# _collection_abc makes it difficult to infer. (We would have to handle AssignName inference in the
# getitem method of the ClassDef class) Instead we put here a mock of the __class_getitem__ method
AstroidManager().register_transform(
ClassDef, easy_class_getitem_inference, _looks_like_subscriptable
)
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