Re: [PATCH v7 2/6] rust: str: implement `Index` for `BStr`

Fiona Behrens
2025-02-24T13:51:00Z

Andreas Hindborg <a.hindborg@kernel.org> writes:

> The `Index` implementation on `BStr` was lost when we switched `BStr` from
> a type alias of `[u8]` to a newtype. This patch adds back `Index` by
> implementing `Index` for `BStr` when `Index` would be implemented for
> `[u8]`.
>
> Signed-off-by: Andreas Hindborg <a.hindborg@kernel.org>

Reviewed-by: Fiona Behrens <me@kloenk.dev>

> ---
> rust/kernel/str.rs | 11 +++++++++++
> 1 file changed, 11 insertions(+)
>
> diff --git a/rust/kernel/str.rs b/rust/kernel/str.rs
> index 002dcddf7c768..ba6b1a5c4f99d 100644
> --- a/rust/kernel/str.rs
> +++ b/rust/kernel/str.rs
> @@ -114,6 +114,17 @@ fn eq(&self, other: &Self) -> bool {
> }
> }
>
> +impl<Idx> Index<Idx> for BStr
> +where
> + [u8]: Index<Idx, Output = [u8]>,
> +{
> + type Output = Self;
> +
> + fn index(&self, index: Idx) -> &Self::Output {
> + BStr::from_bytes(&self.0[index])
> + }
> +}
> +
> /// Creates a new [`BStr`] from a string literal.
> ///
> /// `b_str!` converts the supplied string literal to byte string, so non-ASCII