orx-parallel 4.0.0

Performant parallel computations with an expressive iterator API.
Documentation 
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use crate::infallible::xap::Xap;
use crate::runner::ParRunner;
use orx_concurrent_iter::{ChunkPuller, ConcurrentIter};

pub fn next_any<Q, I, X>(th_idx: usize, state: &Q::State, iter: &I, x: X) -> Option<X::O>
where
    Q: ParRunner,
    I: ConcurrentIter,
    X: Xap<I = I::Item>,
{
    let mut chunk_puller = iter.chunk_puller_by(0, th_idx);

    loop {
        let chunk_size = Q::next_chunk_size(state, iter.size_hint());
        let chunk_state = Q::begin_chunk(th_idx, chunk_size);

        match chunk_size {
            0 | 1 => match iter.next_by(th_idx) {
                Some(i) => {
                    if let Some(val) = x.xap(i).into_iter().next() {
                        Q::broadcast_stop(iter, state, chunk_state);
                        return Some(val);
                    }
                }
                None if iter.is_completed_when_none_returned() => break,
                None => {}
            },
            c => {
                chunk_puller.resize_for_chunk_size(c);

                match chunk_puller.pull() {
                    Some(chunk) => {
                        if let Some(val) = chunk.flat_map(|i| x.xap(i)).next() {
                            Q::broadcast_stop(iter, state, chunk_state);
                            return Some(val);
                        }
                    }
                    None if iter.is_completed_when_none_returned() => break,
                    None => {}
                }
            }
        }
        Q::complete_chunk(state, chunk_state);
    }

    None
}