use std::cell::RefCell;
use std::future::Future;
use std::pin::Pin;
use std::rc::Rc;
use std::task::{Context, Poll, Waker};
#[derive(Debug)]
struct Inner<T> {
value: Option<T>,
waker: Option<Waker>,
}
#[derive(Debug)]
pub struct Sender<T> {
inner: Rc<RefCell<Inner<T>>>,
}
impl<T> Clone for Sender<T> {
fn clone(&self) -> Self {
Self {
inner: self.inner.clone(),
}
}
}
#[derive(Debug)]
pub struct Receiver<T> {
inner: Rc<RefCell<Inner<T>>>,
}
pub fn channel<T>() -> (Sender<T>, Receiver<T>) {
let inner = Rc::new(RefCell::new(Inner {
value: None,
waker: None,
}));
(
Sender {
inner: inner.clone(),
},
Receiver { inner },
)
}
impl<T> Sender<T> {
pub fn send(&self, val: T) {
let mut inner = self.inner.borrow_mut();
inner.value = Some(val);
if let Some(waker) = inner.waker.take() {
waker.wake();
}
}
}
impl<T> Future for Receiver<T> {
type Output = T;
fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<T> {
let mut inner = self.inner.borrow_mut();
if let Some(val) = inner.value.take() {
Poll::Ready(val)
} else {
inner.waker = Some(cx.waker().clone());
Poll::Pending
}
}
}