typeshed/stdlib/2and3/codecs.pyi

import sys
from typing import Any, BinaryIO, Callable, Generator, IO, Iterable, List, Optional, Text, TextIO, Tuple, Type, TypeVar, Union

from abc import abstractmethod
import types

# TODO: this only satisfies the most common interface, where
# bytes (py2 str) is the raw form and str (py2 unicode) is the cooked form.
# In the long run, both should become template parameters maybe?
# There *are* bytes->bytes and str->str encodings in the standard library.
# They are much more common in Python 2 than in Python 3.

_Decoded = Text
_Encoded = bytes

# TODO: It is not possible to specify these signatures correctly, because
# they have an optional positional or keyword argument for errors=.
_Encoder = Callable[[_Decoded], Tuple[_Encoded, int]]  # signature of Codec().encode
_Decoder = Callable[[_Encoded], Tuple[_Decoded, int]]  # signature of Codec().decode
_StreamReader = Callable[[IO[_Encoded]], StreamReader]  # signature of StreamReader __init__
_StreamWriter = Callable[[IO[_Encoded]], StreamWriter]  # signature of StreamWriter __init__
_IncrementalEncoder = Callable[[], IncrementalEncoder]  # signature of IncrementalEncoder __init__
_IncrementalDecoder = Callable[[], IncrementalDecoder]  # signature of IncrementalDecoder __init__
def encode(obj: _Decoded, encoding: str = ..., errors: str = ...) -> _Encoded: ...
def decode(obj: _Encoded, encoding: str = ..., errors: str = ...) -> _Decoded: ...
def lookup(encoding: str) -> CodecInfo: ...

class CodecInfo(Tuple[_Encoder, _Decoder, _StreamReader, _StreamWriter]):
    @property
    def encode(self) -> _Encoder: ...
    @property
    def decode(self) -> _Decoder: ...
    @property
    def streamreader(self) -> _StreamReader: ...
    @property
    def streamwriter(self) -> _StreamWriter: ...
    @property
    def incrementalencoder(self) -> _IncrementalEncoder: ...
    @property
    def incrementaldecoder(self) -> _IncrementalDecoder: ...
    name: str
    def __init__(
        self,
        encode: _Encoder,
        decode: _Decoder,
        streamreader: _StreamReader = ...,
        streamwriter: _StreamWriter = ...,
        incrementalencoder: _IncrementalEncoder = ...,
        incrementaldecoder: _IncrementalDecoder = ...,
        name: str = ...,
    ) -> None: ...

def getencoder(encoding: str) -> _Encoder: ...
def getdecoder(encoding: str) -> _Decoder: ...
def getincrementalencoder(encoding: str) -> _IncrementalEncoder: ...
def getincrementaldecoder(encoding: str) -> _IncrementalDecoder: ...
def getreader(encoding: str) -> _StreamReader: ...
def getwriter(encoding: str) -> _StreamWriter: ...
def register(search_function: Callable[[str], CodecInfo]) -> None: ...
def open(filename: str, mode: str = ..., encoding: str = ..., errors: str = ..., buffering: int = ...) -> StreamReaderWriter: ...
def EncodedFile(file: IO[_Encoded], data_encoding: str, file_encoding: str = ..., errors: str = ...) -> StreamRecoder: ...
def iterencode(iterator: Iterable[_Decoded], encoding: str, errors: str = ...) -> Generator[_Encoded, None, None]: ...
def iterdecode(iterator: Iterable[_Encoded], encoding: str, errors: str = ...) -> Generator[_Decoded, None, None]: ...

BOM: bytes
BOM_BE: bytes
BOM_LE: bytes
BOM_UTF8: bytes
BOM_UTF16: bytes
BOM_UTF16_BE: bytes
BOM_UTF16_LE: bytes
BOM_UTF32: bytes
BOM_UTF32_BE: bytes
BOM_UTF32_LE: bytes

# It is expected that different actions be taken depending on which of the
# three subclasses of `UnicodeError` is actually ...ed. However, the Union
# is still needed for at least one of the cases.
def register_error(name: str, error_handler: Callable[[UnicodeError], Tuple[Union[str, bytes], int]]) -> None: ...
def lookup_error(name: str) -> Callable[[UnicodeError], Tuple[Union[str, bytes], int]]: ...
def strict_errors(exception: UnicodeError) -> Tuple[Union[str, bytes], int]: ...
def replace_errors(exception: UnicodeError) -> Tuple[Union[str, bytes], int]: ...
def ignore_errors(exception: UnicodeError) -> Tuple[Union[str, bytes], int]: ...
def xmlcharrefreplace_errors(exception: UnicodeError) -> Tuple[Union[str, bytes], int]: ...
def backslashreplace_errors(exception: UnicodeError) -> Tuple[Union[str, bytes], int]: ...

class Codec:
    # These are sort of @abstractmethod but sort of not.
    # The StreamReader and StreamWriter subclasses only implement one.
    def encode(self, input: _Decoded, errors: str = ...) -> Tuple[_Encoded, int]: ...
    def decode(self, input: _Encoded, errors: str = ...) -> Tuple[_Decoded, int]: ...

class IncrementalEncoder:
    errors: str
    def __init__(self, errors: str = ...) -> None: ...
    @abstractmethod
    def encode(self, object: _Decoded, final: bool = ...) -> _Encoded: ...
    def reset(self) -> None: ...
    # documentation says int but str is needed for the subclass.
    def getstate(self) -> Union[int, _Decoded]: ...
    def setstate(self, state: Union[int, _Decoded]) -> None: ...

class IncrementalDecoder:
    errors: str
    def __init__(self, errors: str = ...) -> None: ...
    @abstractmethod
    def decode(self, object: _Encoded, final: bool = ...) -> _Decoded: ...
    def reset(self) -> None: ...
    def getstate(self) -> Tuple[_Encoded, int]: ...
    def setstate(self, state: Tuple[_Encoded, int]) -> None: ...

# These are not documented but used in encodings/*.py implementations.
class BufferedIncrementalEncoder(IncrementalEncoder):
    buffer: str
    def __init__(self, errors: str = ...) -> None: ...
    @abstractmethod
    def _buffer_encode(self, input: _Decoded, errors: str, final: bool) -> _Encoded: ...
    def encode(self, input: _Decoded, final: bool = ...) -> _Encoded: ...

class BufferedIncrementalDecoder(IncrementalDecoder):
    buffer: bytes
    def __init__(self, errors: str = ...) -> None: ...
    @abstractmethod
    def _buffer_decode(self, input: _Encoded, errors: str, final: bool) -> Tuple[_Decoded, int]: ...
    def decode(self, object: _Encoded, final: bool = ...) -> _Decoded: ...

# TODO: it is not possible to specify the requirement that all other
# attributes and methods are passed-through from the stream.
class StreamWriter(Codec):
    errors: str
    def __init__(self, stream: IO[_Encoded], errors: str = ...) -> None: ...
    def write(self, obj: _Decoded) -> None: ...
    def writelines(self, list: Iterable[_Decoded]) -> None: ...
    def reset(self) -> None: ...

class StreamReader(Codec):
    errors: str
    def __init__(self, stream: IO[_Encoded], errors: str = ...) -> None: ...
    def read(self, size: int = ..., chars: int = ..., firstline: bool = ...) -> _Decoded: ...
    def readline(self, size: int = ..., keepends: bool = ...) -> _Decoded: ...
    def readlines(self, sizehint: int = ..., keepends: bool = ...) -> List[_Decoded]: ...
    def reset(self) -> None: ...

_T = TypeVar("_T", bound=StreamReaderWriter)

# Doesn't actually inherit from TextIO, but wraps a BinaryIO to provide text reading and writing
# and delegates attributes to the underlying binary stream with __getattr__.
class StreamReaderWriter(TextIO):
    def __init__(self, stream: IO[_Encoded], Reader: _StreamReader, Writer: _StreamWriter, errors: str = ...) -> None: ...
    def read(self, size: int = ...) -> _Decoded: ...
    def readline(self, size: Optional[int] = ...) -> _Decoded: ...
    def readlines(self, sizehint: Optional[int] = ...) -> List[_Decoded]: ...
    if sys.version_info >= (3,):
        def __next__(self) -> Text: ...
    else:
        def next(self) -> Text: ...
    def __iter__(self: _T) -> _T: ...
    # This actually returns None, but that's incompatible with the supertype
    def write(self, data: _Decoded) -> int: ...
    def writelines(self, list: Iterable[_Decoded]) -> None: ...
    def reset(self) -> None: ...
    # Same as write()
    def seek(self, offset: int, whence: int = ...) -> int: ...
    def __enter__(self: _T) -> _T: ...
    def __exit__(
        self, typ: Optional[Type[BaseException]], exc: Optional[BaseException], tb: Optional[types.TracebackType]
    ) -> bool: ...
    def __getattr__(self, name: str) -> Any: ...
    # These methods don't actually exist directly, but they are needed to satisfy the TextIO
    # interface. At runtime, they are delegated through __getattr__.
    def close(self) -> None: ...
    def fileno(self) -> int: ...
    def flush(self) -> None: ...
    def isatty(self) -> bool: ...
    def readable(self) -> bool: ...
    def truncate(self, size: Optional[int] = ...) -> int: ...
    def seekable(self) -> bool: ...
    def tell(self) -> int: ...
    def writable(self) -> bool: ...

_SRT = TypeVar("_SRT", bound=StreamRecoder)

class StreamRecoder(BinaryIO):
    def __init__(
        self,
        stream: IO[_Encoded],
        encode: _Encoder,
        decode: _Decoder,
        Reader: _StreamReader,
        Writer: _StreamWriter,
        errors: str = ...,
    ) -> None: ...
    def read(self, size: int = ...) -> bytes: ...
    def readline(self, size: Optional[int] = ...) -> bytes: ...
    def readlines(self, sizehint: Optional[int] = ...) -> List[bytes]: ...
    if sys.version_info >= (3,):
        def __next__(self) -> bytes: ...
    else:
        def next(self) -> bytes: ...
    def __iter__(self: _SRT) -> _SRT: ...
    def write(self, data: bytes) -> int: ...
    def writelines(self, list: Iterable[bytes]) -> int: ...  # type: ignore  # it's supposed to return None
    def reset(self) -> None: ...
    def __getattr__(self, name: str) -> Any: ...
    def __enter__(self: _SRT) -> _SRT: ...
    def __exit__(
        self, type: Optional[Type[BaseException]], value: Optional[BaseException], tb: Optional[types.TracebackType]
    ) -> bool: ...
    # These methods don't actually exist directly, but they are needed to satisfy the BinaryIO
    # interface. At runtime, they are delegated through __getattr__.
    def seek(self, offset: int, whence: int = ...) -> int: ...
    def close(self) -> None: ...
    def fileno(self) -> int: ...
    def flush(self) -> None: ...
    def isatty(self) -> bool: ...
    def readable(self) -> bool: ...
    def truncate(self, size: Optional[int] = ...) -> int: ...
    def seekable(self) -> bool: ...
    def tell(self) -> int: ...
    def writable(self) -> bool: ...