Add the selectors module (#484)

* Correct some type errors

* Use Any instead of Optional[Any]

stdlib/3.4/selectors.pyi

@@ -0,0 +1,90 @@
+# Stubs for selector
+# See https://docs.python.org/3/library/selectors.html
+
+from typing import Any, List, NamedTuple, Mapping, Tuple, Optional, Union
+from abc import ABCMeta, abstractmethod
+import socket
+
+
+# Type aliases added mainly to preserve some context
+#
+# See https://github.com/python/typeshed/issues/482
+# for details regarding how FileObject is typed.
+FileObject = Union[int, socket.socket]
+FileDescriptor = int
+EventMask = int
+
+
+EVENT_READ = ...  # type: EventMask
+EVENT_WRITE = ...  # type: EventMask
+
+
+SelectorKey = NamedTuple('SelectorKey', [
+    ('fileobj', FileObject),
+    ('fd', FileDescriptor),
+    ('events', EventMask),
+    ('data', Any)
+])
+
+
+class BaseSelector(metaclass=ABCMeta):
+    @abstractmethod
+    def register(self, fileobj: FileObject, events: EventMask, data: Any = None) -> SelectorKey: ...
+
+    @abstractmethod
+    def unregister(self, fileobj: FileObject) -> SelectorKey: ...
+
+    def modify(self, fileobj: FileObject, events: EventMask, data: Any = None) -> SelectorKey: ...
+
+    @abstractmethod
+    def select(self, timeout: Optional[int] = None) -> List[Tuple[SelectorKey, EventMask]]: ...
+
+    def close(self) -> None: ...
+
+    def get_key(self, fileobj: FileObject) -> SelectorKey: ...
+
+    @abstractmethod
+    def get_map(self) -> Mapping[FileObject, SelectorKey]: ...
+
+    def __enter__(self) -> BaseSelector: ...
+
+    def __exit__(self, *args: Any) -> None: ...
+
+class SelectSelector(BaseSelector):
+    def register(self, fileobj: FileObject, events: EventMask, data: Any = None) -> SelectorKey: ...
+    def unregister(self, fileobj: FileObject) -> SelectorKey: ...
+    def select(self, timeout: Optional[int] = None) -> List[Tuple[SelectorKey, EventMask]]: ...
+    def get_map(self) -> Mapping[FileObject, SelectorKey]: ...
+
+class PollSelector(BaseSelector):
+    def register(self, fileobj: FileObject, events: EventMask, data: Any = None) -> SelectorKey: ...
+    def unregister(self, fileobj: FileObject) -> SelectorKey: ...
+    def select(self, timeout: Optional[int] = None) -> List[Tuple[SelectorKey, EventMask]]: ...
+    def get_map(self) -> Mapping[FileObject, SelectorKey]: ...
+
+class EpollSelector(BaseSelector):
+    def fileno(self) -> int: ...
+    def register(self, fileobj: FileObject, events: EventMask, data: Any = None) -> SelectorKey: ...
+    def unregister(self, fileobj: FileObject) -> SelectorKey: ...
+    def select(self, timeout: Optional[int] = None) -> List[Tuple[SelectorKey, EventMask]]: ...
+    def get_map(self) -> Mapping[FileObject, SelectorKey]: ...
+
+class DevpollSelector(BaseSelector):
+    def fileno(self) -> int: ...
+    def register(self, fileobj: FileObject, events: EventMask, data: Any = None) -> SelectorKey: ...
+    def unregister(self, fileobj: FileObject) -> SelectorKey: ...
+    def select(self, timeout: Optional[int] = None) -> List[Tuple[SelectorKey, EventMask]]: ...
+    def get_map(self) -> Mapping[FileObject, SelectorKey]: ...
+
+class KqueueSelector(BaseSelector):
+    def fileno(self) -> int: ...
+    def register(self, fileobj: FileObject, events: EventMask, data: Any = None) -> SelectorKey: ...
+    def unregister(self, fileobj: FileObject) -> SelectorKey: ...
+    def select(self, timeout: Optional[int] = None) -> List[Tuple[SelectorKey, EventMask]]: ...
+    def get_map(self) -> Mapping[FileObject, SelectorKey]: ...
+
+class DefaultSelector(BaseSelector):
+    def register(self, fileobj: FileObject, events: EventMask, data: Any = None) -> SelectorKey: ...
+    def unregister(self, fileobj: FileObject) -> SelectorKey: ...
+    def select(self, timeout: Optional[int] = None) -> List[Tuple[SelectorKey, EventMask]]: ...
+    def get_map(self) -> Mapping[FileObject, SelectorKey]: ...