either/into_either.rs
1//! The trait [`IntoEither`] provides methods for converting a type `Self`, whose
2//! size is constant and known at compile-time, into an [`Either`] variant.
3
4use super::{Either, Left, Right};
5
6//docs.rs/ Provides methods for converting a type `Self` into either a [`Left`] or [`Right`]
7//docs.rs/ variant of [`Either<Self, Self>`](Either).
8//docs.rs/
9//docs.rs/ The [`into_either`](IntoEither::into_either) method takes a [`bool`] to determine
10//docs.rs/ whether to convert to [`Left`] or [`Right`].
11//docs.rs/
12//docs.rs/ The [`into_either_with`](IntoEither::into_either_with) method takes a
13//docs.rs/ [predicate function](FnOnce) to determine whether to convert to [`Left`] or [`Right`].
14pub trait IntoEither: Sized {
15 //docs.rs/ Converts `self` into a [`Left`] variant of [`Either<Self, Self>`](Either)
16 //docs.rs/ if `into_left` is `true`.
17 //docs.rs/ Converts `self` into a [`Right`] variant of [`Either<Self, Self>`](Either)
18 //docs.rs/ otherwise.
19 //docs.rs/
20 //docs.rs/ # Examples
21 //docs.rs/
22 //docs.rs/ ```
23 //docs.rs/ use either::{IntoEither, Left, Right};
24 //docs.rs/
25 //docs.rs/ let x = 0;
26 //docs.rs/ assert_eq!(x.into_either(true), Left(x));
27 //docs.rs/ assert_eq!(x.into_either(false), Right(x));
28 //docs.rs/ ```
29 fn into_either(self, into_left: bool) -> Either<Self, Self> {
30 if into_left {
31 Left(self)
32 } else {
33 Right(self)
34 }
35 }
36
37 //docs.rs/ Converts `self` into a [`Left`] variant of [`Either<Self, Self>`](Either)
38 //docs.rs/ if `into_left(&self)` returns `true`.
39 //docs.rs/ Converts `self` into a [`Right`] variant of [`Either<Self, Self>`](Either)
40 //docs.rs/ otherwise.
41 //docs.rs/
42 //docs.rs/ # Examples
43 //docs.rs/
44 //docs.rs/ ```
45 //docs.rs/ use either::{IntoEither, Left, Right};
46 //docs.rs/
47 //docs.rs/ fn is_even(x: &u8) -> bool {
48 //docs.rs/ x % 2 == 0
49 //docs.rs/ }
50 //docs.rs/
51 //docs.rs/ let x = 0;
52 //docs.rs/ assert_eq!(x.into_either_with(is_even), Left(x));
53 //docs.rs/ assert_eq!(x.into_either_with(|x| !is_even(x)), Right(x));
54 //docs.rs/ ```
55 fn into_either_with<F>(self, into_left: F) -> Either<Self, Self>
56 where
57 F: FnOnce(&Self) -> bool,
58 {
59 let into_left = into_left(&self);
60 self.into_either(into_left)
61 }
62}
63
64impl<T> IntoEither for T {}