| /// Extracts the successful type of a [`Poll<T>`]. |
| /// |
| /// This macro bakes in propagation of [`Pending`] signals by returning early. |
| /// |
| /// [`Poll<T>`]: crate::task::Poll |
| /// [`Pending`]: crate::task::Poll::Pending |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::task::{ready, Context, Poll}; |
| /// use std::future::{self, Future}; |
| /// use std::pin::Pin; |
| /// |
| /// pub fn do_poll(cx: &mut Context<'_>) -> Poll<()> { |
| /// let mut fut = future::ready(42); |
| /// let fut = Pin::new(&mut fut); |
| /// |
| /// let num = ready!(fut.poll(cx)); |
| /// # let _ = num; |
| /// // ... use num |
| /// |
| /// Poll::Ready(()) |
| /// } |
| /// ``` |
| /// |
| /// The `ready!` call expands to: |
| /// |
| /// ``` |
| /// # use std::task::{Context, Poll}; |
| /// # use std::future::{self, Future}; |
| /// # use std::pin::Pin; |
| /// # |
| /// # pub fn do_poll(cx: &mut Context<'_>) -> Poll<()> { |
| /// # let mut fut = future::ready(42); |
| /// # let fut = Pin::new(&mut fut); |
| /// # |
| /// let num = match fut.poll(cx) { |
| /// Poll::Ready(t) => t, |
| /// Poll::Pending => return Poll::Pending, |
| /// }; |
| /// # let _ = num; // to silence unused warning |
| /// # // ... use num |
| /// # |
| /// # Poll::Ready(()) |
| /// # } |
| /// ``` |
| #[stable(feature = "ready_macro", since = "1.64.0")] |
| #[rustc_macro_transparency = "semitransparent"] |
| pub macro ready($e:expr) { |
| match $e { |
| $crate::task::Poll::Ready(t) => t, |
| $crate::task::Poll::Pending => { |
| return $crate::task::Poll::Pending; |
| } |
| } |
| } |