compat.py

# Copyright (C) 2008, 2009 Michael Trier (mtrier@gmail.com) and contributors
#
# This module is part of GitPython and is released under the
# 3-Clause BSD License: https://opensource.org/license/bsd-3-clause/

"""Utilities to help provide compatibility with Python 3.

This module exists for historical reasons. Code outside GitPython may make use of public
members of this module, but is unlikely to benefit from doing so. GitPython continues to
use some of these utilities, in some cases for compatibility across different platforms.
"""

import locale
import os
import sys

from gitdb.utils.encoding import force_bytes, force_text  # noqa: F401  # @UnusedImport

# typing --------------------------------------------------------------------

from typing import (  # noqa: F401
    Any,
    AnyStr,
    Dict,
    IO,
    Optional,
    Tuple,
    Type,
    Union,
    overload,
)

# ---------------------------------------------------------------------------


is_win = os.name == "nt"
"""Deprecated alias for ``os.name == "nt"`` to check for native Windows.

This is deprecated because it is clearer to write out :attr:`os.name` or
:attr:`sys.platform` checks explicitly, especially in cases where it matters which is
used.

:note:
    ``is_win`` is ``False`` on Cygwin, but is often wrongly assumed ``True``. To detect
    Cygwin, use ``sys.platform == "cygwin"``.
"""

is_posix = os.name == "posix"
"""Deprecated alias for ``os.name == "posix"`` to check for Unix-like ("POSIX") systems.

This is deprecated because it clearer to write out :attr:`os.name` or
:attr:`sys.platform` checks explicitly, especially in cases where it matters which is
used.

:note:
    For POSIX systems, more detailed information is available in :attr:`sys.platform`,
    while :attr:`os.name` is always ``"posix"`` on such systems, including macOS
    (Darwin).
"""

is_darwin = sys.platform == "darwin"
"""Deprecated alias for ``sys.platform == "darwin"`` to check for macOS (Darwin).

This is deprecated because it clearer to write out :attr:`os.name` or
:attr:`sys.platform` checks explicitly.

:note:
    For macOS (Darwin), ``os.name == "posix"`` as in other Unix-like systems, while
    ``sys.platform == "darwin"``.
"""

defenc = sys.getfilesystemencoding()
"""The encoding used to convert between Unicode and bytes filenames."""


@overload
def safe_decode(s: None) -> None: ...


@overload
def safe_decode(s: AnyStr) -> str: ...


def safe_decode(s: Union[AnyStr, None]) -> Optional[str]:
    """Safely decode a binary string to Unicode."""
    if isinstance(s, str):
        return s
    elif isinstance(s, bytes):
        return s.decode(defenc, "surrogateescape")
    elif s is None:
        return None
    else:
        raise TypeError("Expected bytes or text, but got %r" % (s,))


@overload
def safe_encode(s: None) -> None: ...


@overload
def safe_encode(s: AnyStr) -> bytes: ...


def safe_encode(s: Optional[AnyStr]) -> Optional[bytes]:
    """Safely encode a binary string to Unicode."""
    if isinstance(s, str):
        return s.encode(defenc)
    elif isinstance(s, bytes):
        return s
    elif s is None:
        return None
    else:
        raise TypeError("Expected bytes or text, but got %r" % (s,))


@overload
def win_encode(s: None) -> None: ...


@overload
def win_encode(s: AnyStr) -> bytes: ...


def win_encode(s: Optional[AnyStr]) -> Optional[bytes]:
    """Encode Unicode strings for process arguments on Windows."""
    if isinstance(s, str):
        return s.encode(locale.getpreferredencoding(False))
    elif isinstance(s, bytes):
        return s
    elif s is not None:
        raise TypeError("Expected bytes or text, but got %r" % (s,))
    return None