blob: 4b1f4cd7d4733e71858864490b71b63d5283a121 [file] [log] [blame]
use {Future, Poll, Async};
/// Future for the `map` combinator, changing the type of a future.
/// This is created by the `Future::map` method.
#[must_use = "futures do nothing unless polled"]
pub struct Map<A, F> where A: Future {
future: A,
f: Option<F>,
pub fn new<A, F>(future: A, f: F) -> Map<A, F>
where A: Future,
Map {
future: future,
f: Some(f),
impl<U, A, F> Future for Map<A, F>
where A: Future,
F: FnOnce(A::Item) -> U,
type Item = U;
type Error = A::Error;
fn poll(&mut self) -> Poll<U, A::Error> {
let e = match self.future.poll() {
Ok(Async::NotReady) => return Ok(Async::NotReady),
Ok(Async::Ready(e)) => Ok(e),
Err(e) => Err(e),
};"cannot poll Map twice"))