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 stdlibx.option.types import Nothing, Some
 7from typing_extensions import ParamSpec, TypeIs
 8
 9if TYPE_CHECKING:
10    from stdlibx.option.types import Operation, Option
11
12
13T = TypeVar("T")
14E = TypeVar("E")
15U = TypeVar("U")
16P = ParamSpec("P")
17
18

[docs]
19def some(value: T) -> Option[T]:
20    return _Some(value)

21
22

[docs]
23def nothing() -> Option[T]:
24    return _Nothing()

25
26

[docs]
27def is_some(opt: Option[T]) -> TypeIs[Some[T]]:
28    return opt.is_some()

29
30

[docs]
31def is_none(opt: Option[T]) -> TypeIs[Nothing]:
32    return opt.is_none()

33
34

[docs]
35def maybe(func: Callable[P, T | None], *args: P.args, **kwargs: P.kwargs) -> Option[T]:
36    value = func(*args, **kwargs)
37    if value is None:
38        return nothing()
39    return some(value)

40
41

[docs]
42def optional(func: Callable[P, T | None]) -> Callable[P, Option[T]]:
43    @wraps(func)
44    def _wrapped(*args: P.args, **kwargs: P.kwargs) -> Option[T]:
45        result = func(*args, **kwargs)
46        if result is None:
47            return nothing()
48        return some(result)
49
50    return _wrapped

51
52
53class _Some(Generic[T]):
54    __match_args__ = ("value",)
55    __slots__ = ("value",)
56
57    value: T
58
59    def __init__(self, value: T) -> None:
60        self.value = value
61
62    def __repr__(self) -> str:
63        return f"Some({self.value!r})"
64
65    def __eq__(self, other: object) -> bool:
66        if isinstance(other, Some):
67            return other.value == self.value
68        return False
69
70    def is_some(self):
71        return True
72
73    def is_none(self):
74        return False
75
76    def apply(self, operation: Operation[Option[T], U]) -> U:
77        return operation(self)
78
79
80class _Nothing:
81    __slots__ = ()
82
83    def __repr__(self) -> str:
84        return "Nothing()"
85
86    def __eq__(self, other: object) -> bool:
87        return isinstance(other, Nothing)
88
89    def is_some(self):
90        return False
91
92    def is_none(self):
93        return True
94
95    def apply(self, operation: Operation[Option[T], U]) -> U:
96        return operation(self)