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#[macro_export]
macro_rules! try_poll {
($e:expr) => (match $e {
$crate::Poll::NotReady => return $crate::Poll::NotReady,
$crate::Poll::Ok(t) => Ok(t),
$crate::Poll::Err(e) => Err(e),
})
}
/// Possible return values from the `Future::poll` method.
#[derive(Copy, Clone, Debug, PartialEq)]
pub enum Poll<T, E> {
/// Indicates that the future is not ready yet, ask again later.
NotReady,
/// Indicates that the future has completed successfully, and this value is
/// what the future completed with.
Ok(T),
/// Indicates that the future has failed, and this error is what the future
/// failed with.
Err(E),
}
impl<T, E> Poll<T, E> {
/// Change the success type of this `Poll` value with the closure provided
pub fn map<F, U>(self, f: F) -> Poll<U, E>
where F: FnOnce(T) -> U
{
match self {
Poll::NotReady => Poll::NotReady,
Poll::Ok(t) => Poll::Ok(f(t)),
Poll::Err(e) => Poll::Err(e),
}
}
/// Change the error type of this `Poll` value with the closure provided
pub fn map_err<F, U>(self, f: F) -> Poll<T, U>
where F: FnOnce(E) -> U
{
match self {
Poll::NotReady => Poll::NotReady,
Poll::Ok(t) => Poll::Ok(t),
Poll::Err(e) => Poll::Err(f(e)),
}
}
/// Returns whether this is `Poll::NotReady`
pub fn is_not_ready(&self) -> bool {
match *self {
Poll::NotReady => true,
_ => false,
}
}
/// Returns whether this is either `Poll::Ok` or `Poll::Err`
pub fn is_ready(&self) -> bool {
!self.is_not_ready()
}
/// Unwraps this `Poll` into a `Result`, panicking if it's not ready.
pub fn unwrap(self) -> Result<T, E> {
match self {
Poll::Ok(t) => Ok(t),
Poll::Err(t) => Err(t),
Poll::NotReady => panic!("unwrapping a Poll that wasn't ready"),
}
}
}
impl<T, E> From<Result<T, E>> for Poll<T, E> {
fn from(r: Result<T, E>) -> Poll<T, E> {
match r {
Ok(t) => Poll::Ok(t),
Err(t) => Poll::Err(t),
}
}
}