mirror of
https://github.com/async-rs/async-std.git
synced 2025-07-09 22:41:35 +00:00
50 lines
1.3 KiB
Rust
50 lines
1.3 KiB
Rust
use std::pin::Pin;
|
|
|
|
use super::fuse::Fuse;
|
|
use crate::stream::Stream;
|
|
use crate::task::{Context, Poll};
|
|
|
|
/// Chains two streams one after another.
|
|
#[derive(Debug)]
|
|
pub struct Chain<S, U> {
|
|
first: Fuse<S>,
|
|
second: Fuse<U>,
|
|
}
|
|
|
|
impl<S: Stream, U: Stream> Chain<S, U> {
|
|
pin_utils::unsafe_pinned!(first: Fuse<S>);
|
|
pin_utils::unsafe_pinned!(second: Fuse<U>);
|
|
|
|
pub(super) fn new(first: S, second: U) -> Self {
|
|
Chain {
|
|
first: first.fuse(),
|
|
second: second.fuse(),
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<S: Stream, U: Stream<Item = S::Item>> Stream for Chain<S, U> {
|
|
type Item = S::Item;
|
|
|
|
fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
|
|
if !self.first.done {
|
|
let next = futures_core::ready!(self.as_mut().first().poll_next(cx));
|
|
if let Some(next) = next {
|
|
return Poll::Ready(Some(next));
|
|
}
|
|
}
|
|
|
|
if !self.second.done {
|
|
let next = futures_core::ready!(self.as_mut().second().poll_next(cx));
|
|
if let Some(next) = next {
|
|
return Poll::Ready(Some(next));
|
|
}
|
|
}
|
|
|
|
if self.first.done && self.second.done {
|
|
return Poll::Ready(None);
|
|
}
|
|
|
|
Poll::Pending
|
|
}
|
|
}
|