make io.pyi import everything from _io.py(i), like io.py does (#1395)

* make io.pyi import _io.py(i), like io.py does
* make write/writelines take 'Any', on _IOBase
* Add missing constructors, fix inconsistencies.
* Also, as far as possible, try to simplify, by moving methods into base
classes.
* fix lint+mypy warnings
* add missing __enter__ methods
* make _IOBase inherit from BinaryIO
* make _TextIOBase not subclass _IOBase

stdlib/2/io.pyi

@@ -7,98 +7,37 @@
 from typing import List, BinaryIO, TextIO, IO, overload, Iterator, Iterable, Any, Union, Optional
 import _io
 
-DEFAULT_BUFFER_SIZE = 0
+from _io import BlockingIOError as BlockingIOError
+from _io import BufferedRWPair as BufferedRWPair
+from _io import BufferedRandom as BufferedRandom
+from _io import BufferedReader as BufferedReader
+from _io import BufferedWriter as BufferedWriter
+from _io import BytesIO as BytesIO
+from _io import DEFAULT_BUFFER_SIZE as DEFAULT_BUFFER_SIZE
+from _io import FileIO as FileIO
+from _io import IncrementalNewlineDecoder as IncrementalNewlineDecoder
+from _io import StringIO as StringIO
+from _io import TextIOWrapper as TextIOWrapper
+from _io import UnsupportedOperation as UnsupportedOperation
+from _io import open as open
 
-def open(file: Union[str, unicode, int],
+def _OpenWrapper(file: Union[str, unicode, int],
          mode: unicode = ..., buffering: int = ..., encoding: unicode = ...,
          errors: unicode = ..., newline: unicode = ...,
          closefd: bool = ...) -> IO[Any]: ...
 
+SEEK_SET = ...  # type: int
+SEEK_CUR = ...  # type: int
+SEEK_END = ...  # type: int
+
+
 class IOBase(_io._IOBase): ...
 
-class BytesIO(BinaryIO):
-    def __init__(self, initial_bytes: str = ...) -> None: ...
-    # TODO getbuffer
-    # TODO see comments in BinaryIO for missing functionality
-    def close(self) -> None: ...
-    def closed(self) -> bool: ...
-    def fileno(self) -> int: ...
-    def flush(self) -> None: ...
-    def isatty(self) -> bool: ...
-    def read(self, n: int = ...) -> str: ...
-    def readable(self) -> bool: ...
-    def readline(self, limit: int = ...) -> str: ...
-    def readlines(self, hint: int = ...) -> List[str]: ...
-    def seek(self, offset: int, whence: int = ...) -> int: ...
-    def seekable(self) -> bool: ...
-    def tell(self) -> int: ...
-    def truncate(self, size: Optional[int] = ...) -> int: ...
-    def writable(self) -> bool: ...
-    def write(self, s: str) -> int: ...
-    def writelines(self, lines: Iterable[str]) -> None: ...
-    def getvalue(self) -> str: ...
-    def read1(self) -> str: ...
+class RawIOBase(_io._RawIOBase, IOBase):
+    pass
 
-    def __iter__(self) -> Iterator[str]: ...
-    def next(self) -> str: ...
-    def __enter__(self) -> 'BytesIO': ...
-    def __exit__(self, type, value, traceback) -> bool: ...
+class BufferedIOBase(_io._BufferedIOBase, IOBase):
+    pass
 
-class StringIO(TextIO):
-    def __init__(self, initial_value: unicode = ...,
-                 newline: unicode = ...) -> None: ...
-    # TODO see comments in BinaryIO for missing functionality
-    name = ...  # type: str
-    def close(self) -> None: ...
-    def closed(self) -> bool: ...
-    def fileno(self) -> int: ...
-    def flush(self) -> None: ...
-    def isatty(self) -> bool: ...
-    def read(self, n: int = ...) -> unicode: ...
-    def readable(self) -> bool: ...
-    def readline(self, limit: int = ...) -> unicode: ...
-    def readlines(self, hint: int = ...) -> List[unicode]: ...
-    def seek(self, offset: int, whence: int = ...) -> int: ...
-    def seekable(self) -> bool: ...
-    def tell(self) -> int: ...
-    def truncate(self, size: Optional[int] = ...) -> int: ...
-    def writable(self) -> bool: ...
-    def write(self, s: unicode) -> int: ...
-    def writelines(self, lines: Iterable[unicode]) -> None: ...
-    def getvalue(self) -> unicode: ...
-
-    def __iter__(self) -> Iterator[unicode]: ...
-    def next(self) -> unicode: ...
-    def __enter__(self) -> 'StringIO': ...
-    def __exit__(self, type, value, traceback) -> bool: ...
-
-class TextIOWrapper(TextIO):
-    # write_through is undocumented but used by subprocess
-    def __init__(self, buffer: IO[str], encoding: unicode = ...,
-                 errors: unicode = ..., newline: unicode = ...,
-                 line_buffering: bool = ...,
-                 write_through: bool = ...) -> None: ...
-    # TODO see comments in BinaryIO for missing functionality
-    def close(self) -> None: ...
-    def closed(self) -> bool: ...
-    def fileno(self) -> int: ...
-    def flush(self) -> None: ...
-    def isatty(self) -> bool: ...
-    def read(self, n: int = ...) -> unicode: ...
-    def readable(self) -> bool: ...
-    def readline(self, limit: int = ...) -> unicode: ...
-    def readlines(self, hint: int = ...) -> List[unicode]: ...
-    def seek(self, offset: int, whence: int = ...) -> int: ...
-    def seekable(self) -> bool: ...
-    def tell(self) -> int: ...
-    def truncate(self, size: Optional[int] = ...) -> int: ...
-    def writable(self) -> bool: ...
-    def write(self, s: unicode) -> int: ...
-    def writelines(self, lines: Iterable[unicode]) -> None: ...
-
-    def __iter__(self) -> Iterator[unicode]: ...
-    def next(self) -> unicode: ...
-    def __enter__(self) -> StringIO: ...
-    def __exit__(self, type, value, traceback) -> bool: ...
-
-class BufferedIOBase(_io._BufferedIOBase, IOBase): ...
+class TextIOBase(_io._TextIOBase, IOBase):  # type: ignore
+    pass