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/// Provides methods for converting a type `Self` into either a [`Left`] or [`Right`]
7/// variant of [`Either<Self, Self>`](Either).
8///
9/// The [`into_either`](IntoEither::into_either) method takes a [`bool`] to determine
10/// whether to convert to [`Left`] or [`Right`].
11///
12/// The [`into_either_with`](IntoEither::into_either_with) method takes a
13/// [predicate function](FnOnce) to determine whether to convert to [`Left`] or [`Right`].
14pub trait IntoEither: Sized {
15    /// Converts `self` into a [`Left`] variant of [`Either<Self, Self>`](Either)
16    /// if `into_left` is `true`.
17    /// Converts `self` into a [`Right`] variant of [`Either<Self, Self>`](Either)
18    /// otherwise.
19    ///
20    /// # Examples
21    ///
22    /// ```
23    /// use either::{IntoEither, Left, Right};
24    ///
25    /// let x = 0;
26    /// assert_eq!(x.into_either(true), Left(x));
27    /// assert_eq!(x.into_either(false), Right(x));
28    /// ```
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    /// Converts `self` into a [`Left`] variant of [`Either<Self, Self>`](Either)
38    /// if `into_left(&self)` returns `true`.
39    /// Converts `self` into a [`Right`] variant of [`Either<Self, Self>`](Either)
40    /// otherwise.
41    ///
42    /// # Examples
43    ///
44    /// ```
45    /// use either::{IntoEither, Left, Right};
46    ///
47    /// fn is_even(x: &u8) -> bool {
48    ///     x % 2 == 0
49    /// }
50    ///
51    /// let x = 0;
52    /// assert_eq!(x.into_either_with(is_even), Left(x));
53    /// assert_eq!(x.into_either_with(|x| !is_even(x)), Right(x));
54    /// ```
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 {}
either/into_either.rs

either/
into_either.rs
