Rust dynamic queue

dynamic_queue.rs

/*

Usage

async fn t0() {
    tokio::time::sleep(std::time::Duration::from_secs(2)).await;
    println!("Hello");
}

async fn t1() {
    tokio::time::sleep(std::time::Duration::from_secs(2)).await;
    println!("World");
}

#[tokio::main]
async fn main() {
    env_logger::init(); // Log to stderr (if you run with `RUST_LOG=debug`).

    let mut queue = Queue::new();
    queue.en_queue(task!(t0()));
    queue.en_queue(task!(t1()));

    queue.run().await;
}

*/

use std::future::Future;
use std::pin::Pin;

type AsyncFn = Pin<Box<dyn Future<Output=()>>>;

macro_rules! task {
    ($function:expr) => {
        Box::pin($function)
    };
}

struct Queue {
    tasks: Vec<AsyncFn>,
}

impl Queue {
    fn new() -> Self {
        Self { tasks: Vec::new() }
    }

    fn en_queue(&mut self, task: AsyncFn) {
        self.tasks.insert(0, task);
    }

    async fn run(&mut self) {
        while let Some(func) = self.tasks.pop() {
            func.await;
        }
    }
}