blob: b6a2ab46f4e0a04539421c30c0758f0f3a150579 [file] [log] [blame]
use super::{TryChain, TryChainAction};
use core::pin::Pin;
use futures_core::future::{FusedFuture, Future, TryFuture};
use futures_core::task::{LocalWaker, Poll};
use pin_utils::unsafe_pinned;
/// Future for the [`and_then`](super::TryFutureExt::and_then) combinator.
#[derive(Debug)]
#[must_use = "futures do nothing unless polled"]
pub struct AndThen<Fut1, Fut2, F> {
try_chain: TryChain<Fut1, Fut2, F>,
}
impl<Fut1, Fut2, F> AndThen<Fut1, Fut2, F>
where Fut1: TryFuture,
Fut2: TryFuture,
{
unsafe_pinned!(try_chain: TryChain<Fut1, Fut2, F>);
/// Creates a new `Then`.
pub(super) fn new(future: Fut1, f: F) -> AndThen<Fut1, Fut2, F> {
AndThen {
try_chain: TryChain::new(future, f),
}
}
}
impl<Fut1, Fut2, F> FusedFuture for AndThen<Fut1, Fut2, F>
where Fut1: TryFuture,
Fut2: TryFuture<Error = Fut1::Error>,
F: FnOnce(Fut1::Ok) -> Fut2,
{
fn is_terminated(&self) -> bool {
self.try_chain.is_terminated()
}
}
impl<Fut1, Fut2, F> Future for AndThen<Fut1, Fut2, F>
where Fut1: TryFuture,
Fut2: TryFuture<Error = Fut1::Error>,
F: FnOnce(Fut1::Ok) -> Fut2,
{
type Output = Result<Fut2::Ok, Fut2::Error>;
fn poll(self: Pin<&mut Self>, lw: &LocalWaker) -> Poll<Self::Output> {
self.try_chain().poll(lw, |result, async_op| {
match result {
Ok(ok) => TryChainAction::Future(async_op(ok)),
Err(err) => TryChainAction::Output(Err(err)),
}
})
}
}