Add mmap (#412)

* py3 done

* have to have specific version, to much changes

* py2 done

* merge py2 and py3 version

* fix duplicate definition in mypy

* apply version specific def

* rename ContextManager, single line for import

Author: tharvik

stdlib/2and3/mmap.pyi

@@ -0,0 +1,78 @@
+# Stubs for mmap
+
+from typing import Optional, Sequence, Union, Generic, TypeVar, overload
+import sys
+
+
+_T = TypeVar('_T', str, bytes)
+
+# TODO already in PEP, have to get added to mypy
+from typing import Type
+from types import TracebackType
+_C = TypeVar('_C')
+class _ContextManager(Generic[_C]):
+    def __enter__(self) -> _C: ...
+    def __exit__(self, exc_type: Optional[Type[BaseException]],
+                 exc_val: Optional[Exception],
+                 exc_tb: Optional[TracebackType]) -> bool: ...
+
+
+ACCESS_READ = ... # type: int
+ACCESS_WRITE = ... # type: int
+ACCESS_COPY = ... # type: int
+
+ALLOCATIONGRANULARITY = ... # type: int
+
+if sys.platform != 'win32':
+    MAP_PRIVATE = ... # type: int
+    MAP_SHARED = ... # type: int
+    PROT_READ = ... # type: int
+    PROT_WRITE = ... # type: int
+
+    PAGESIZE = ... # type: int
+
+class _mmap(Generic[_T]):
+    if sys.platform == 'win32':
+        def __init__(self, fileno: int, length: int,
+                     tagname: Optional[str] = ..., access: int = ...,
+                     offset: int = ...) -> None: ...
+    else:
+        def __init__(self,  # type: ignore
+                     fileno: int, length: int, flags: int = ...,
+                     prot: int = ..., access: int = ...,
+                     offset: int = ...) -> None: ...
+    def close(self) -> None: ...
+    def find(self, sub: _T,
+             start: int = ..., end: int = ...) -> int: ...
+    def flush(self, offset: int = ..., size: int = ...) -> int: ...
+    def move(self, dest: int, src: int, count: int) -> None: ...
+    def read(self, n: int = ...) -> _T: ...
+    def read_byte(self) -> _T: ...
+    def readline(self) -> _T: ...
+    def resize(self, newsize: int) -> None: ...
+    def seek(self, pos: int, whence: int = ...) -> None: ...
+    def size(self) -> int: ...
+    def tell(self) -> int: ...
+    def write(self, bytes: _T) -> None: ...
+    def write_byte(self, byte: _T) -> None: ...
+    def __len__(self) -> int: ...
+
+if sys.version_info >= (3,):
+    class mmap(_mmap, _ContextManager[mmap], Sequence[bytes]):
+        closed = ... # type: bool
+        def rfind(self, sub: bytes, start: int = ..., stop: int = ...) -> int: ...
+        @overload  # type: ignore
+        def __getitem__(self, index: int) -> int: ...
+        @overload
+        def __getitem__(self, index: slice) -> bytes: ...
+        def __delitem__(self, index: Union[int, slice]) -> None: ...
+        @overload
+        def __setitem__(self, index: int, object: int) -> None: ...
+        @overload
+        def __setitem__(self, index: slice, object: bytes) -> None: ...
+else:
+    class mmap(_mmap, Sequence[str]):
+        def rfind(self, string: str, start: int = ..., stop: int = ...) -> int: ...
+        def __getitem__(self, index: Union[int, slice]) -> str: ...
+        def __delitem__(self, index: Union[int, slice]) -> None: ...
+        def __setitem__(self, index: Union[int, slice], object: str) -> None: ...