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42 lines
859 B
Python

from __future__ import annotations
from .base import Always, Filter, FilterOrBool, Never
__all__ = [
"to_filter",
"is_true",
]
_always = Always()
_never = Never()
_bool_to_filter: dict[bool, Filter] = {
True: _always,
False: _never,
}
def to_filter(bool_or_filter: FilterOrBool) -> Filter:
"""
Accept both booleans and Filters as input and
turn it into a Filter.
"""
if isinstance(bool_or_filter, bool):
return _bool_to_filter[bool_or_filter]
if isinstance(bool_or_filter, Filter):
return bool_or_filter
raise TypeError(f"Expecting a bool or a Filter instance. Got {bool_or_filter!r}")
def is_true(value: FilterOrBool) -> bool:
"""
Test whether `value` is True. In case of a Filter, call it.
:param value: Boolean or `Filter` instance.
"""
return to_filter(value)()