Compute VWAP in rust

vwap.rs

use itertools::put_back;
use itertools::Itertools;

fn main() {
    let qp_it = put_back([(1, 2), (2, 2), (3, 2), (4, 3), (5, 2)].into_iter());
    let acc_qp_it = qp_it.batching(|it| {
        let mut q_acc = 0;
        let mut qp_acc = 0;
        while q_acc < 5 {
            match it.next() {
                None => break,
                Some((q, p)) => {
                    if q_acc + q > 5 {
                        let carry = q_acc + q - 5;
                        it.put_back((carry, p));
                        q_acc = 5;
                        qp_acc += (q - carry) * p;
                    } else {
                        q_acc += q;
                        qp_acc += q * p;
                    }
                }
            }
        }
        if q_acc == 0 {
            None
        } else {
            Some((q_acc, qp_acc))
        }
    });

    println!("{:?}", acc_qp_it.format(" "));
}