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Diffstat (limited to 'tokio/src/future/poll_fn.rs')
-rw-r--r-- | tokio/src/future/poll_fn.rs | 38 |
1 files changed, 38 insertions, 0 deletions
diff --git a/tokio/src/future/poll_fn.rs b/tokio/src/future/poll_fn.rs new file mode 100644 index 00000000..ce2a5524 --- /dev/null +++ b/tokio/src/future/poll_fn.rs @@ -0,0 +1,38 @@ +//! Definition of the `PollFn` adapter combinator + +use std::fmt; +use std::future::Future; +use std::pin::Pin; +use std::task::{Context, Poll}; + +/// Future for the [`poll_fn`] function. +pub(crate) struct PollFn<F> { + f: F, +} + +impl<F> Unpin for PollFn<F> {} + +/// Creates a new future wrapping around a function returning [`Poll`]. +pub(crate) fn poll_fn<T, F>(f: F) -> PollFn<F> +where + F: FnMut(&mut Context<'_>) -> Poll<T>, +{ + PollFn { f } +} + +impl<F> fmt::Debug for PollFn<F> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + f.debug_struct("PollFn").finish() + } +} + +impl<T, F> Future for PollFn<F> +where + F: FnMut(&mut Context<'_>) -> Poll<T>, +{ + type Output = T; + + fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<T> { + (&mut self.f)(cx) + } +} |