65 lines
2.0 KiB
Rust
65 lines
2.0 KiB
Rust
//! The trait [`IntoEither`] provides methods for converting a type `Self`, whose
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//! size is constant and known at compile-time, into an [`Either`] variant.
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use super::{Either, Left, Right};
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/// Provides methods for converting a type `Self` into either a [`Left`] or [`Right`]
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/// variant of [`Either<Self, Self>`](Either).
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///
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/// The [`into_either`](IntoEither::into_either) method takes a [`bool`] to determine
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/// whether to convert to [`Left`] or [`Right`].
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///
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/// The [`into_either_with`](IntoEither::into_either_with) method takes a
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/// [predicate function](FnOnce) to determine whether to convert to [`Left`] or [`Right`].
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pub trait IntoEither: Sized {
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/// Converts `self` into a [`Left`] variant of [`Either<Self, Self>`](Either)
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/// if `into_left` is `true`.
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/// Converts `self` into a [`Right`] variant of [`Either<Self, Self>`](Either)
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/// otherwise.
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///
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/// # Examples
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///
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/// ```
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/// use either::{IntoEither, Left, Right};
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///
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/// let x = 0;
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/// assert_eq!(x.into_either(true), Left(x));
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/// assert_eq!(x.into_either(false), Right(x));
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/// ```
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fn into_either(self, into_left: bool) -> Either<Self, Self> {
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if into_left {
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Left(self)
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} else {
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Right(self)
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}
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}
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/// Converts `self` into a [`Left`] variant of [`Either<Self, Self>`](Either)
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/// if `into_left(&self)` returns `true`.
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/// Converts `self` into a [`Right`] variant of [`Either<Self, Self>`](Either)
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/// otherwise.
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///
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/// # Examples
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///
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/// ```
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/// use either::{IntoEither, Left, Right};
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///
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/// fn is_even(x: &u8) -> bool {
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/// x % 2 == 0
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/// }
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///
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/// let x = 0;
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/// assert_eq!(x.into_either_with(is_even), Left(x));
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/// assert_eq!(x.into_either_with(|x| !is_even(x)), Right(x));
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/// ```
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fn into_either_with<F>(self, into_left: F) -> Either<Self, Self>
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where
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F: FnOnce(&Self) -> bool,
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{
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let into_left = into_left(&self);
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self.into_either(into_left)
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}
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}
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impl<T> IntoEither for T {}
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