projects/linux·blob v6.19 · refs

49 lines · 1.9 KiB

1// SPDX-License-Identifier: GPL-2.0
2
3//! Additional (and temporary) slice helpers.
4
5/// Extension trait providing a portable version of [`as_flattened`] and
6/// [`as_flattened_mut`].
7///
8/// In Rust 1.80, the previously unstable `slice::flatten` family of methods
9/// have been stabilized and renamed from `flatten` to `as_flattened`.
10///
11/// This creates an issue for as long as the MSRV is < 1.80, as the same functionality is provided
12/// by different methods depending on the compiler version.
13///
14/// This extension trait solves this by abstracting `as_flatten` and calling the correct method
15/// depending on the Rust version.
16///
17/// This trait can be removed once the MSRV passes 1.80.
18///
19/// [`as_flattened`]: https://doc.rust-lang.org/std/primitive.slice.html#method.as_flattened
20/// [`as_flattened_mut`]: https://doc.rust-lang.org/std/primitive.slice.html#method.as_flattened_mut
21#[cfg(not(CONFIG_RUSTC_HAS_SLICE_AS_FLATTENED))]
22pub trait AsFlattened<T> {
23 /// Takes a `&[[T; N]]` and flattens it to a `&[T]`.
24 ///
25 /// This is an portable layer on top of [`as_flattened`]; see its documentation for details.
26 ///
27 /// [`as_flattened`]: https://doc.rust-lang.org/std/primitive.slice.html#method.as_flattened
28 fn as_flattened(&self) -> &[T];
29
30 /// Takes a `&mut [[T; N]]` and flattens it to a `&mut [T]`.
31 ///
32 /// This is an portable layer on top of [`as_flattened_mut`]; see its documentation for details.
33 ///
34 /// [`as_flattened_mut`]: https://doc.rust-lang.org/std/primitive.slice.html#method.as_flattened_mut
35 fn as_flattened_mut(&mut self) -> &mut [T];
36}
37
38#[cfg(not(CONFIG_RUSTC_HAS_SLICE_AS_FLATTENED))]
39impl<T, const N: usize> AsFlattened<T> for [[T; N]] {
40 #[allow(clippy::incompatible_msrv)]
41 fn as_flattened(&self) -> &[T] {
42 self.flatten()
43 }
44
45 #[allow(clippy::incompatible_msrv)]
46 fn as_flattened_mut(&mut self) -> &mut [T] {
47 self.flatten_mut()
48 }
49}