Delayed streaming works

1 files changed, 28 insertions, 0 deletions

diff --git a/src/main.rs b/src/main.rs
index 55c435d..b6e9f06 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -3,11 +3,39 @@ use async_stream::stream;
 use futures_util::pin_mut;
 use futures_util::stream::StreamExt;
 
+use std::future::Future;
+use std::pin::Pin;
+use std::task::{Context, Poll};
+use std::time::{Duration, Instant};
+
+struct Delay {
+    when: Instant,
+}
+
+impl Future for Delay {
+    type Output = &'static str;
+
+    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<&'static str> {
+        if Instant::now() >= self.when {
+            println!("Hello world");
+            Poll::Ready("done")
+        } else {
+            // Ignore this line for now.
+            cx.waker().wake_by_ref();
+            Poll::Pending
+        }
+    }
+}
+
 #[tokio::main]
 async fn main() {
     let s = stream! {
+        let mut when = Instant::now();
         for i in 0..3 {
+            let delay = Delay { when };
+            delay.await;
             yield i;
+            when += Duration::from_millis(1000);
         }
     };