Source code for returns.interfaces.swappable

from abc import abstractmethod
from typing import ClassVar, NoReturn, Sequence, TypeVar, final

from returns.interfaces import bimappable
from returns.primitives.asserts import assert_equal
from import KindN
from returns.primitives.laws import (

_FirstType = TypeVar('_FirstType')
_SecondType = TypeVar('_SecondType')
_ThirdType = TypeVar('_ThirdType')

_SwappableType = TypeVar('_SwappableType', bound='SwappableN')

[docs]@final class _LawSpec(LawSpecDef): """Laws for :class:`~SwappableN` type.""" __slots__ = ()
[docs] @law_definition def double_swap_law( container: 'SwappableN[_FirstType, _SecondType, _ThirdType]', ) -> None: """ Swapping container twice. It ensure that we get the initial value back. In other words, swapping twice does nothing. """ assert_equal( container, container.swap().swap(), )
[docs]class SwappableN( bimappable.BiMappableN[_FirstType, _SecondType, _ThirdType], Lawful['SwappableN[_FirstType, _SecondType, _ThirdType]'], ): """Interface that allows swapping first and second type values.""" __slots__ = () _laws: ClassVar[Sequence[Law]] = ( Law1(_LawSpec.double_swap_law), )
[docs] @abstractmethod def swap( self: _SwappableType, ) -> KindN[_SwappableType, _SecondType, _FirstType, _ThirdType]: """Swaps first and second types in ``SwappableN``."""
#: Type alias for kinds with two type arguments. Swappable2 = SwappableN[_FirstType, _SecondType, NoReturn] #: Type alias for kinds with three type arguments. Swappable3 = SwappableN[_FirstType, _SecondType, _ThirdType]