mercurial/thirdparty/attr/filters.py

py3: conditionalize test-flagprocessor.t on Python 3.8

For reasons I don't understand, Python 3.8 is outputting a different
lint in the traceback than prior Pythons.

The lines in question are:

    flagutil.addflagprocessor(
        REVIDX_NOOP, (noopdonothingread, noopdonothing, validatehash,)
    )

Python <3.8 prints the 2nd line but 3.8 the first line. Perhaps Python
changed its traceback logic to always print the first line of a
multiple line expression?

Whatever the case, with this change, the test now passes on
Python 3.8.

Differential Revision: https://phab.mercurial-scm.org/D7945

"""
Commonly useful filters for :func:`attr.asdict`.
"""

from __future__ import absolute_import, division, print_function

from ._compat import isclass
from ._make import Attribute


def _split_what(what):
    """
    Returns a tuple of `frozenset`s of classes and attributes.
    """
    return (
        frozenset(cls for cls in what if isclass(cls)),
        frozenset(cls for cls in what if isinstance(cls, Attribute)),
    )


def include(*what):
    r"""
    Whitelist *what*.

    :param what: What to whitelist.
    :type what: :class:`list` of :class:`type` or :class:`attr.Attribute`\ s

    :rtype: :class:`callable`
    """
    cls, attrs = _split_what(what)

    def include_(attribute, value):
        return value.__class__ in cls or attribute in attrs

    return include_


def exclude(*what):
    r"""
    Blacklist *what*.

    :param what: What to blacklist.
    :type what: :class:`list` of classes or :class:`attr.Attribute`\ s.

    :rtype: :class:`callable`
    """
    cls, attrs = _split_what(what)

    def exclude_(attribute, value):
        return value.__class__ not in cls and attribute not in attrs

    return exclude_