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use {Future, IntoFuture, Task, Poll};
use chain::Chain;
pub struct AndThen<A, B, F> where A: Future, B: IntoFuture {
state: Chain<A, B::Future, F>,
}
pub fn new<A, B, F>(future: A, f: F) -> AndThen<A, B, F>
where A: Future,
B: IntoFuture,
F: Send + 'static,
{
AndThen {
state: Chain::new(future, f),
}
}
impl<A, B, F> Future for AndThen<A, B, F>
where A: Future,
B: IntoFuture<Error=A::Error>,
F: FnOnce(A::Item) -> B + Send + 'static,
{
type Item = B::Item;
type Error = B::Error;
fn poll(&mut self, task: &mut Task) -> Poll<B::Item, B::Error> {
self.state.poll(task, |result, f| {
result.map(|e| {
Err(f(e).into_future())
})
})
}
fn schedule(&mut self, task: &mut Task) {
self.state.schedule(task)
}
fn tailcall(&mut self)
-> Option<Box<Future<Item=Self::Item, Error=Self::Error>>> {
self.state.tailcall()
}
}