| use super::{TryChain, TryChainAction}; |
| use core::pin::Pin; |
| use futures_core::future::{FusedFuture, Future, TryFuture}; |
| use futures_core::task::{Context, Poll}; |
| use pin_utils::unsafe_pinned; |
| |
| /// Future for the [`or_else`](super::TryFutureExt::or_else) method. |
| #[derive(Debug)] |
| #[must_use = "futures do nothing unless you `.await` or poll them"] |
| pub struct OrElse<Fut1, Fut2, F> { |
| try_chain: TryChain<Fut1, Fut2, F>, |
| } |
| |
| impl<Fut1, Fut2, F> OrElse<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) -> OrElse<Fut1, Fut2, F> { |
| OrElse { |
| try_chain: TryChain::new(future, f), |
| } |
| } |
| } |
| |
| impl<Fut1, Fut2, F> FusedFuture for OrElse<Fut1, Fut2, F> |
| where Fut1: TryFuture, |
| Fut2: TryFuture<Ok = Fut1::Ok>, |
| F: FnOnce(Fut1::Error) -> Fut2, |
| { |
| fn is_terminated(&self) -> bool { |
| self.try_chain.is_terminated() |
| } |
| } |
| |
| impl<Fut1, Fut2, F> Future for OrElse<Fut1, Fut2, F> |
| where Fut1: TryFuture, |
| Fut2: TryFuture<Ok = Fut1::Ok>, |
| F: FnOnce(Fut1::Error) -> Fut2, |
| { |
| type Output = Result<Fut2::Ok, Fut2::Error>; |
| |
| fn poll( |
| self: Pin<&mut Self>, |
| cx: &mut Context<'_>, |
| ) -> Poll<Self::Output> { |
| self.try_chain().poll(cx, |result, async_op| { |
| match result { |
| Ok(ok) => TryChainAction::Output(Ok(ok)), |
| Err(err) => TryChainAction::Future(async_op(err)), |
| } |
| }) |
| } |
| } |