| use core::pin::Pin; |
| use futures_core::future::{FusedFuture, Future}; |
| use futures_core::task::{Context, Poll}; |
| use pin_utils::{unsafe_pinned, unsafe_unpinned}; |
| |
| /// Future for the [`inspect`](super::FutureExt::inspect) method. |
| #[derive(Debug)] |
| #[must_use = "futures do nothing unless polled"] |
| pub struct Inspect<Fut, F> where Fut: Future { |
| future: Fut, |
| f: Option<F>, |
| } |
| |
| impl<Fut: Future, F: FnOnce(&Fut::Output)> Inspect<Fut, F> { |
| unsafe_pinned!(future: Fut); |
| unsafe_unpinned!(f: Option<F>); |
| |
| pub(super) fn new(future: Fut, f: F) -> Inspect<Fut, F> { |
| Inspect { |
| future, |
| f: Some(f), |
| } |
| } |
| } |
| |
| impl<Fut: Future + Unpin, F> Unpin for Inspect<Fut, F> {} |
| |
| impl<Fut: Future + FusedFuture, F> FusedFuture for Inspect<Fut, F> { |
| fn is_terminated(&self) -> bool { self.future.is_terminated() } |
| } |
| |
| impl<Fut, F> Future for Inspect<Fut, F> |
| where Fut: Future, |
| F: FnOnce(&Fut::Output), |
| { |
| type Output = Fut::Output; |
| |
| fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Fut::Output> { |
| let e = match self.as_mut().future().poll(cx) { |
| Poll::Pending => return Poll::Pending, |
| Poll::Ready(e) => e, |
| }; |
| |
| let f = self.as_mut().f().take().expect("cannot poll Inspect twice"); |
| f(&e); |
| Poll::Ready(e) |
| } |
| } |