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use crate::{consumer::Consumer, producer::Producer};
/// Moves at most `count` items from the `src` consumer to the `dst` producer.
///
/// Consumer and producer may be of different buffers as well as of the same one.
/// `count` is the number of items being moved, if `None` - as much as possible items will be moved.
///
/// Returns number of items been moved.
pub fn transfer<T, C: Consumer<Item = T>, P: Producer<Item = T>>(src: &mut C, dst: &mut P, count: Option<usize>) -> usize {
let (src_left, src_right) = src.occupied_slices();
let (dst_left, dst_right) = dst.vacant_slices_mut();
let src_iter = src_left.iter().chain(src_right.iter());
let dst_iter = dst_left.iter_mut().chain(dst_right.iter_mut());
let mut actual_count = 0;
for (src_elem, dst_place) in src_iter.zip(dst_iter) {
if let Some(count) = count
&& actual_count >= count
{
break;
}
unsafe { dst_place.write(src_elem.as_ptr().read()) };
actual_count += 1;
}
unsafe { src.advance_read_index(actual_count) };
unsafe { dst.advance_write_index(actual_count) };
actual_count
}