view mercurial/interfaces/modules.py @ 51964:d7f17819ae9e

interfaces: introduce and use a protocol class for the `mpatch` module

See f2832de2a46c for details when this was done for the `bdiff` module.

Two things worth pointing out-

  1) The `cffi` module "inherits" the `pure` implementation of `patchedsize()`
     because of its wildcard import.
  2) It's odd that the `mpatchError` lives in both `pure` and `cext` modules.

I initially thought to move the exception into the new class, and make the
existing class name an alias to the class in the new location, but the exception
is created in C code by the `cext` module, so that won't work.  I don't think a
protocol class is approriate, because there's nothing special about the class to
distinguish from any other `Exception`.  Fortunately, nobody is catching this
exception in core, so we can kick the can down the road.

# modules.py - protocol classes for dynamically loaded modules
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

from __future__ import annotations

import typing

from typing import (
    Callable,
    List,
    Optional,
    Protocol,
    Tuple,
)

if typing.TYPE_CHECKING:
    BDiffBlock = Tuple[int, int, int, int]
    """An entry in the list returned by bdiff.{xdiff,}blocks()."""

    BDiffBlocksFnc = Callable[[bytes, bytes], List[BDiffBlock]]
    """The signature of `bdiff.blocks()` and `bdiff.xdiffblocks()`."""


class Base85(Protocol):
    """A Protocol class for the various base85 module implementations."""

    def b85encode(self, text: bytes, pad: bool = False) -> bytes:
        """encode text in base85 format"""

    def b85decode(self, text: bytes) -> bytes:
        """decode base85-encoded text"""


class BDiff(Protocol):
    """A Protocol class for the various bdiff module implementations."""

    def splitnewlines(self, text: bytes) -> List[bytes]:
        """like str.splitlines, but only split on newlines."""

    def bdiff(self, a: bytes, b: bytes) -> bytes:
        ...

    def blocks(self, a: bytes, b: bytes) -> List[BDiffBlock]:
        ...

    def fixws(self, text: bytes, allws: bool) -> bytes:
        ...

    xdiffblocks: Optional[BDiffBlocksFnc]
    """This method is currently only available in the ``cext`` module."""


class CharEncoding(Protocol):
    """A Protocol class for the various charencoding module implementations."""

    def isasciistr(self, s: bytes) -> bool:
        """Can the byte string be decoded with the ``ascii`` codec?"""

    def asciilower(self, s: bytes) -> bytes:
        """convert a string to lowercase if ASCII

        Raises UnicodeDecodeError if non-ASCII characters are found."""

    def asciiupper(self, s: bytes) -> bytes:
        """convert a string to uppercase if ASCII

        Raises UnicodeDecodeError if non-ASCII characters are found."""

    def jsonescapeu8fast(self, u8chars: bytes, paranoid: bool) -> bytes:
        """Convert a UTF-8 byte string to JSON-escaped form (fast path)

        Raises ValueError if non-ASCII characters have to be escaped.
        """


class MPatch(Protocol):
    """A protocol class for the various mpatch module implementations."""

    def patches(self, a: bytes, bins: List[bytes]) -> bytes:
        ...

    def patchedsize(self, orig: int, delta: bytes) -> int:
        ...