typeshed/stdlib/2and3/codecs.pyi

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

from abc import abstractmethod
import types

if sys.version_info < (3,) or sys.version_info >= (3, 8):
    from typing import Literal
else:
    from typing_extensions import Literal

# 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

class _Encoder(Protocol):
    def __call__(self, input: _Decoded, errors: str = ...) -> Tuple[_Encoded, int]: ...  # signature of Codec().encode
class _Decoder(Protocol):
    def __call__(self, input: _Encoded, errors: str = ...) -> Tuple[_Decoded, int]: ...  # signature of Codec().decode

class _StreamReader(Protocol):
    def __call__(self, stream: IO[_Encoded], errors: str = ...) -> StreamReader: ...
class _StreamWriter(Protocol):
    def __call__(self, stream: IO[_Encoded], errors: str = ...) -> StreamWriter: ...

class _IncrementalEncoder(Protocol):
    def __call__(self, errors: str = ...) -> IncrementalEncoder: ...
class _IncrementalDecoder(Protocol):
    def __call__(self, errors: str = ...) -> IncrementalDecoder: ...

# The type ignore on `encode` and `decode` is to avoid issues with overlapping overloads, for more details, see #300
# mypy and pytype disagree about where the type ignore can and cannot go, so alias the long type
_BytesToBytesEncodingT = Literal[
    "base64",
    "base_64",
    "base64_codec",
    "bz2",
    "bz2_codec",
    "hex",
    "hex_codec",
    "quopri",
    "quotedprintable",
    "quoted_printable",
    "quopri_codec",
    "uu",
    "uu_codec",
    "zip",
    "zlib",
    "zlib_codec",
]
@overload
def encode(obj: bytes, encoding: _BytesToBytesEncodingT, errors: str = ...) -> bytes: ...
@overload
def encode(obj: str, encoding: Literal["rot13", "rot_13"] = ..., errors: str = ...) -> str: ...  # type: ignore
@overload
def encode(obj: _Decoded, encoding: str = ..., errors: str = ...) -> _Encoded: ...

@overload
def decode(obj: bytes, encoding: _BytesToBytesEncodingT, errors: str = ...) -> bytes: ...  # type: ignore
@overload
def decode(obj: str, encoding: Literal["rot13", "rot_13"] = ..., errors: str = ...) -> Text: ...
@overload
def decode(obj: _Encoded, encoding: str = ..., errors: str = ...) -> _Decoded: ...

def lookup(encoding: str) -> CodecInfo: ...
def utf_16_be_decode(__obj: _Encoded, __errors: str = ..., __final: bool = ...) -> Tuple[_Decoded, int]: ...  # undocumented
def utf_16_be_encode(__obj: _Decoded, __errors: str = ...) -> Tuple[_Encoded, int]: ...  # undocumented

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], Optional[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: ...

_SW = TypeVar("_SW", bound=StreamWriter)

# 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: ...
    def __enter__(self: _SW) -> _SW: ...
    def __exit__(
        self, typ: Optional[Type[BaseException]], exc: Optional[BaseException], tb: Optional[types.TracebackType]
    ) -> None: ...
    def __getattr__(self, name: str) -> Any: ...

_SR = TypeVar("_SR", bound=StreamReader)

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: ...
    def __enter__(self: _SR) -> _SR: ...
    def __exit__(
        self, typ: Optional[Type[BaseException]], exc: Optional[BaseException], tb: Optional[types.TracebackType]
    ) -> None: ...
    def __iter__(self) -> Iterator[_Decoded]: ...
    def __getattr__(self, name: str) -> Any: ...

_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]
    ) -> None: ...
    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]
    ) -> None: ...
    # 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: ...