Function str_concat::concat_slice_unordered

pub unsafe fn concat_slice_unordered<'a, T>(
    a: &'a [T], 
    b: &'a [T]
) -> Result<&'a [T], Error>

Concatenate two adjacent slices no matter their order.

This is the same as concat_slice except that it also concatenates b to a if b is in front of a (in which case of concat_slice errors). Keep in mind that slices of zero-sized types (ZST) will still not be concatenated.

Safety

The provided slices must come from the same underlying allocation. The adjacency test can not reliably differentiate between the one-past-the-end pointer of one allocation and the start of another. However, all slices must be within a single allocation.

Examples

Reversed order:

let s = [0, 1, 2, 3, 4, 5, 6];
unsafe {
    // SAFETY: slices from the same bytes originally.
    assert_eq!(
        [0, 1, 2, 3, 4, 5, 6],
        concat_slice_unordered(&s[5..7], &s[..5]).unwrap());
}

Normal order:

let s = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
unsafe {
    // SAFETY: slices from the same bytes originally.
    assert_eq!(
        [0, 1, 2, 3, 4, 5, 6],
        concat_slice_unordered(&s[..5], &s[5..7]).unwrap())
}