PEP 0492 -- Coroutines with async and await syntax. Issue #24017.
diff --git a/Lib/_collections_abc.py b/Lib/_collections_abc.py
index cb87e6b..ea80403 100644
--- a/Lib/_collections_abc.py
+++ b/Lib/_collections_abc.py
@@ -9,7 +9,8 @@
from abc import ABCMeta, abstractmethod
import sys
-__all__ = ["Hashable", "Iterable", "Iterator", "Generator",
+__all__ = ["Awaitable", "Coroutine",
+ "Hashable", "Iterable", "Iterator", "Generator",
"Sized", "Container", "Callable",
"Set", "MutableSet",
"Mapping", "MutableMapping",
@@ -74,6 +75,79 @@
return NotImplemented
+class _CoroutineMeta(ABCMeta):
+
+ def __instancecheck__(cls, instance):
+ # 0x80 = CO_COROUTINE
+ # 0x100 = CO_ITERABLE_COROUTINE
+ # We don't want to import 'inspect' module, as
+ # a dependency for 'collections.abc'.
+ CO_COROUTINES = 0x80 | 0x100
+
+ if (isinstance(instance, generator) and
+ instance.gi_code.co_flags & CO_COROUTINES):
+
+ return True
+
+ return super().__instancecheck__(instance)
+
+
+class Coroutine(metaclass=_CoroutineMeta):
+
+ __slots__ = ()
+
+ @abstractmethod
+ def send(self, value):
+ """Send a value into the coroutine.
+ Return next yielded value or raise StopIteration.
+ """
+ raise StopIteration
+
+ @abstractmethod
+ def throw(self, typ, val=None, tb=None):
+ """Raise an exception in the coroutine.
+ Return next yielded value or raise StopIteration.
+ """
+ if val is None:
+ if tb is None:
+ raise typ
+ val = typ()
+ if tb is not None:
+ val = val.with_traceback(tb)
+ raise val
+
+ def close(self):
+ """Raise GeneratorExit inside coroutine.
+ """
+ try:
+ self.throw(GeneratorExit)
+ except (GeneratorExit, StopIteration):
+ pass
+ else:
+ raise RuntimeError("coroutine ignored GeneratorExit")
+
+
+class Awaitable(metaclass=_CoroutineMeta):
+
+ __slots__ = ()
+
+ @abstractmethod
+ def __await__(self):
+ yield
+
+ @classmethod
+ def __subclasshook__(cls, C):
+ if cls is Awaitable:
+ for B in C.__mro__:
+ if "__await__" in B.__dict__:
+ if B.__dict__["__await__"]:
+ return True
+ break
+ return NotImplemented
+
+Awaitable.register(Coroutine)
+
+
class Iterable(metaclass=ABCMeta):
__slots__ = ()