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```
``````//! The trait [`IntoEither`] provides methods for converting a type `Self`, whose
//! size is constant and known at compile-time, into an [`Either`] variant.

use super::{Either, Left, Right};

/// Provides methods for converting a type `Self` into either a [`Left`] or [`Right`]
/// variant of [`Either<Self, Self>`](Either).
///
/// The [`into_either`](IntoEither::into_either) method takes a [`bool`] to determine
/// whether to convert to [`Left`] or [`Right`].
///
/// The [`into_either_with`](IntoEither::into_either_with) method takes a
/// [predicate function](FnOnce) to determine whether to convert to [`Left`] or [`Right`].
pub trait IntoEither: Sized {
/// Converts `self` into a [`Left`] variant of [`Either<Self, Self>`](Either)
/// if `into_left` is `true`.
/// Converts `self` into a [`Right`] variant of [`Either<Self, Self>`](Either)
/// otherwise.
///
/// # Examples
///
/// ```
/// use either::{IntoEither, Left, Right};
///
/// let x = 0;
/// assert_eq!(x.into_either(true), Left(x));
/// assert_eq!(x.into_either(false), Right(x));
/// ```
fn into_either(self, into_left: bool) -> Either<Self, Self> {
if into_left {
Left(self)
} else {
Right(self)
}
}

/// Converts `self` into a [`Left`] variant of [`Either<Self, Self>`](Either)
/// if `into_left(&self)` returns `true`.
/// Converts `self` into a [`Right`] variant of [`Either<Self, Self>`](Either)
/// otherwise.
///
/// # Examples
///
/// ```
/// use either::{IntoEither, Left, Right};
///
/// fn is_even(x: &u8) -> bool {
///     x % 2 == 0
/// }
///
/// let x = 0;
/// assert_eq!(x.into_either_with(is_even), Left(x));
/// assert_eq!(x.into_either_with(|x| !is_even(x)), Right(x));
/// ```
fn into_either_with<F>(self, into_left: F) -> Either<Self, Self>
where
F: FnOnce(&Self) -> bool,
{
let into_left = into_left(&self);
self.into_either(into_left)
}
}

impl<T> IntoEither for T {}
``````