Source code for stdlibx.option._option

 1from __future__ import annotations
 2
 3from functools import wraps
 4from typing import TYPE_CHECKING, Callable, Generic, TypeVar
 5
 6from typing_extensions import ParamSpec, TypeAlias, TypeGuard
 7
 8if TYPE_CHECKING:
 9    from stdlibx.option._types import Operation
10
11
12T = TypeVar("T")
13E = TypeVar("E")
14U = TypeVar("U")
15P = ParamSpec("P")
16
17Option: TypeAlias = "Some[T] | Nothing[T]"
18
19

[docs]
20def is_some(opt: Option[T]) -> TypeGuard[Some[T]]:
21    return opt.is_some()

22
23

[docs]
24def is_none(opt: Option[T]) -> TypeGuard[Nothing[T]]:
25    return opt.is_none()

26
27

[docs]
28def optional_of(
29    func: Callable[P, T | None], *args: P.args, **kwargs: P.kwargs
30) -> Option[T]:
31    value = func(*args, **kwargs)
32    if value is None:
33        return Nothing()
34    return Some(value)

35
36

[docs]
37def as_optional(func: Callable[P, T | None]) -> Callable[P, Option[T]]:
38    @wraps(func)
39    def _wrapped(*args: P.args, **kwargs: P.kwargs) -> Option[T]:
40        result = func(*args, **kwargs)
41        if result is None:
42            return Nothing()
43        return Some(result)
44
45    return _wrapped

46
47

[docs]
48class Some(Generic[T]):
49    __match_args__ = ("value",)
50    __slots__ = ("value",)
51
52    value: T
53
54    def __init__(self, value: T) -> None:
55        self.value = value
56
57    def __repr__(self) -> str:
58        return f"Some({self.value!r})"
59
60    def __eq__(self, other: object) -> bool:
61        if isinstance(other, Some):
62            return other.value == self.value
63        return False
64

[docs]
65    def is_some(self):
66        return True

67

[docs]
68    def is_none(self):
69        return False

70

[docs]
71    def apply(self, operation: Operation[Option[T], U]) -> U:
72        return operation(self)


73
74

[docs]
75class Nothing(Generic[T]):
76    __slots__ = ()
77
78    def __repr__(self) -> str:
79        return "Nothing()"
80
81    def __eq__(self, other: object) -> bool:
82        return isinstance(other, Nothing)
83

[docs]
84    def is_some(self):
85        return False

86

[docs]
87    def is_none(self):
88        return True

89

[docs]
90    def apply(self, operation: Operation[Option[T], U]) -> U:
91        return operation(self)