Function bytes_rfind_keep 

pub const fn bytes_rfind_keep<'a>(
    this: &'a [u8],
    needle: &[u8],
) -> Option<&'a [u8]>

Truncates this to the last instance of needle.

Return None if no instance of needle is found.

Return Some(this) if needle is empty.

Motivation

This function exists because calling bytes_rfind + slice_up_to when the "rust_1_64" feature is disabled is slower than it could be, since the slice has to be traversed twice.

Example

use konst::slice::bytes_rfind_keep;

{
    const FOUND: Option<&[u8]> = bytes_rfind_keep(b"foo bar _ bar baz", b"bar");
    assert_eq!(FOUND, Some(&b"foo bar _ bar"[..]));
}
{
    const NOT_FOUND: Option<&[u8]> = bytes_rfind_keep(b"foo bar baz", b"qux");
    assert_eq!(NOT_FOUND, None);
}
{
    const EMPTY_NEEDLE: Option<&[u8]> = bytes_rfind_keep(b"foo bar baz", b"");
    assert_eq!(EMPTY_NEEDLE, Some(&b"foo bar baz"[..]));
}