Current File : //lib/python3/dist-packages/attr/_compat.py
# SPDX-License-Identifier: MIT
import inspect
import platform
import sys
import threading
from collections.abc import Mapping, Sequence # noqa: F401
from typing import _GenericAlias
PYPY = platform.python_implementation() == "PyPy"
PY_3_8_PLUS = sys.version_info[:2] >= (3, 8)
PY_3_9_PLUS = sys.version_info[:2] >= (3, 9)
PY310 = sys.version_info[:2] >= (3, 10)
PY_3_12_PLUS = sys.version_info[:2] >= (3, 12)
if sys.version_info < (3, 8):
try:
from typing_extensions import Protocol
except ImportError: # pragma: no cover
Protocol = object
else:
from typing import Protocol # noqa: F401
class _AnnotationExtractor:
"""
Extract type annotations from a callable, returning None whenever there
is none.
"""
__slots__ = ["sig"]
def __init__(self, callable):
try:
self.sig = inspect.signature(callable)
except (ValueError, TypeError): # inspect failed
self.sig = None
def get_first_param_type(self):
"""
Return the type annotation of the first argument if it's not empty.
"""
if not self.sig:
return None
params = list(self.sig.parameters.values())
if params and params[0].annotation is not inspect.Parameter.empty:
return params[0].annotation
return None
def get_return_type(self):
"""
Return the return type if it's not empty.
"""
if (
self.sig
and self.sig.return_annotation is not inspect.Signature.empty
):
return self.sig.return_annotation
return None
# Thread-local global to track attrs instances which are already being repr'd.
# This is needed because there is no other (thread-safe) way to pass info
# about the instances that are already being repr'd through the call stack
# in order to ensure we don't perform infinite recursion.
#
# For instance, if an instance contains a dict which contains that instance,
# we need to know that we're already repr'ing the outside instance from within
# the dict's repr() call.
#
# This lives here rather than in _make.py so that the functions in _make.py
# don't have a direct reference to the thread-local in their globals dict.
# If they have such a reference, it breaks cloudpickle.
repr_context = threading.local()
def get_generic_base(cl):
"""If this is a generic class (A[str]), return the generic base for it."""
if cl.__class__ is _GenericAlias:
return cl.__origin__
return None
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