view mercurial/thirdparty/attr/filters.py @ 46779:49fd21f32695

revlog: guarantee that p1 != null if a non-null parent exists

This change does not affect the hashing (which already did this
transformation), but can change the log output in the rare case where
this behavior was observed in repositories. The change can simplify
iteration code where regular changesets and merges are distinct
branches.

Differential Revision: https://phab.mercurial-scm.org/D10150

"""
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_