from typing import Iterable
from typing import Literal
from .base import Predicate
from .base import T
[docs]def true(_value: object, /) -> Literal[True]:
"""Always return :py:const:`True`."""
return True
[docs]def false(_value: object, /) -> Literal[False]:
"""Always return :py:const:`False`."""
return False
[docs]def negate(predicate: Predicate[T]) -> Predicate[T]:
"""Negate a given predicate."""
def check(value: T, /) -> bool:
return not predicate(value)
return check
[docs]def truthy(value: object, /) -> bool:
"""Return :py:const:`True` for truthy objects."""
return bool(value)
[docs]def falsy(value: object, /) -> bool:
"""Return :py:const:`True` for falsy objects."""
return negate(truthy)(value)
[docs]def both(p: Predicate[T], q: Predicate[T]) -> Predicate[T]:
"""
Create a new predicate that succeeds when both of the given predicates succeed.
"""
def check(value: T, /) -> bool:
return p(value) and q(value)
return check
[docs]def either(p: Predicate[T], q: Predicate[T]) -> Predicate[T]:
"""
Create a new predicate that succeeds when at least one of the given predicates
succeed.
"""
def check(value: T, /) -> bool:
return p(value) or q(value)
return check
[docs]def xor(p: Predicate[T], q: Predicate[T]) -> Predicate[T]:
"""
Create a new predicate that succeeds when one of the given predicates succeed, but
not both.
"""
def check(value: T, /) -> bool:
return p(value) ^ q(value)
return check
[docs]def all_of(predicates: Iterable[Predicate[T]]) -> Predicate[T]:
"""Create a new predicate that succeeds when all of the given predicates succeed."""
predicates = tuple(predicates)
def check(value: T, /) -> bool:
return all(p(value) for p in predicates)
return check
[docs]def any_of(predicates: Iterable[Predicate[T]]) -> Predicate[T]:
"""
Create a new predicate that succeeds when at least one of the given predicates
succeed.
"""
predicates = tuple(predicates)
def check(value: T, /) -> bool:
return any(p(value) for p in predicates)
return check
[docs]def one_of(predicates: Iterable[Predicate[T]]) -> Predicate[T]:
"""
Create a new predicate that succeeds when exactly one of the given predicates
succeed.
"""
predicates = tuple(predicates)
def check(value: T, /) -> bool:
return 1 == sum(p(value) for p in predicates)
return check