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

- From: Fiona Behrens \<hidden\>
- Date: 2025-02-24 13:51:00 
- List: linux-modules
- Page: https://ratatoskr.run/linux-modules/2025/02/2941075
- Thread: https://ratatoskr.run/rust-for-linux/2025/02/2941075/t.md

```text
Andreas Hindborg [ref] 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 <redacted>

> ---
>  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
```