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use std::future::Future; use std::pin::Pin; use std::task::{Context, Poll}; /// Future for the [`ok`](ok()) function. /// /// `pub` in order to use the future as an associated type in a sealed trait. #[derive(Debug)] // Used as an associated type in a "sealed" trait. #[allow(unreachable_pub)] pub struct Ready<T>(Option<T>); impl<T> Unpin for Ready<T> {} impl<T> Future for Ready<T> { type Output = T; #[inline] fn poll(mut self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<T> { Poll::Ready(self.0.take().unwrap()) } } /// Creates a future that is immediately ready with a success value. pub(crate) fn ok<T, E>(t: T) -> Ready<Result<T, E>> { Ready(Some(Ok(t))) }