to_chunks.rs

to_chunks.rs

fn to_chunks<I: Iterator, const N: usize>(mut iter: I) -> impl Iterator<Item=[I::Item; N]> + {
    std::iter::from_fn(move || {
        let mut buf: [MaybeUninit<I::Item>; N] = unsafe { MaybeUninit::uninit().assume_init() };
        for i in 0..N {
            match iter.next() {
                Some(val) => buf[i].write(val),
                None => return None
            };
        }
        Some(unsafe { (&buf as *const _ as *const [I::Item; N]).read() })
    })
}