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use {Future, IntoFuture, Poll, Async};
use core::option;
#[derive(Debug, Clone)]
#[must_use = "futures do nothing unless polled"]
pub struct Option<F> {
inner: option::Option<F>,
}
impl<F> IntoFuture for option::Option<F> where F: Future {
type Future = Option<F>;
type Item = option::Option<F::Item>;
type Error = F::Error;
fn into_future(self) -> Self::Future {
Option { inner: self }
}
}
impl<F> Future for Option<F> where F: Future {
type Item = option::Option<F::Item>;
type Error = F::Error;
fn poll(&mut self) -> Poll<Self::Item, Self::Error> {
match self.inner {
None => Ok(Async::Ready(None)),
Some(ref mut x) => x.poll().map(|x| x.map(Some)),
}
}
}