blob: c7e1cde5bbc31f5012e4b72caf9e78954aad8269 [file] [log] [blame]
use {Async, Future, IntoFuture, Poll};
use stream::Stream;
/// A stream combinator which executes a unit closure over each item on a
/// stream.
///
/// This structure is returned by the `Stream::for_each` method.
#[derive(Debug)]
#[must_use = "streams do nothing unless polled"]
pub struct ForEach<S, F, U> where U: IntoFuture {
stream: S,
f: F,
fut: Option<U::Future>,
}
pub fn new<S, F, U>(s: S, f: F) -> ForEach<S, F, U>
where S: Stream,
F: FnMut(S::Item) -> U,
U: IntoFuture<Item = (), Error = S::Error>,
{
ForEach {
stream: s,
f: f,
fut: None,
}
}
impl<S, F, U> Future for ForEach<S, F, U>
where S: Stream,
F: FnMut(S::Item) -> U,
U: IntoFuture<Item= (), Error = S::Error>,
{
type Item = ();
type Error = S::Error;
fn poll(&mut self) -> Poll<(), S::Error> {
loop {
if let Some(mut fut) = self.fut.take() {
if fut.poll()?.is_not_ready() {
self.fut = Some(fut);
return Ok(Async::NotReady);
}
}
match try_ready!(self.stream.poll()) {
Some(e) => self.fut = Some((self.f)(e).into_future()),
None => return Ok(Async::Ready(())),
}
}
}
}