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Wrap state enum in public struct

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This commit is contained in:
Abhishek C. Sharma 2019-11-04 13:58:14 +05:30
parent e0910be8fb
commit a3e68704bc
1 changed files with 16 additions and 10 deletions
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26
src/future/future/flatten.rs
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@ -5,9 +5,13 @@ use crate::future::Future;
use crate::future::IntoFuture; use crate::future::IntoFuture;
use crate::task::{Context, Poll}; use crate::task::{Context, Poll};
#[doc(hidden)]
#[derive(Debug)] #[derive(Debug)]
pub enum FlattenFuture<Fut1, Fut2> { pub struct FlattenFuture<Fut1, Fut2> {
state: State<Fut1, Fut2>,
}
#[derive(Debug)]
enum State<Fut1, Fut2> {
First(Fut1), First(Fut1),
Second(Fut2), Second(Fut2),
Empty, Empty,
@ -15,7 +19,9 @@ pub enum FlattenFuture<Fut1, Fut2> {
impl<Fut1, Fut2> FlattenFuture<Fut1, Fut2> { impl<Fut1, Fut2> FlattenFuture<Fut1, Fut2> {
pub fn new(future: Fut1) -> FlattenFuture<Fut1, Fut2> { pub fn new(future: Fut1) -> FlattenFuture<Fut1, Fut2> {
FlattenFuture::First(future) FlattenFuture {
state: State::First(future),
}
} }
} }
@ -27,19 +33,19 @@ where
type Output = <Fut1::Output as IntoFuture>::Output; type Output = <Fut1::Output as IntoFuture>::Output;
fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> { fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
let this = unsafe { self.get_unchecked_mut() }; let Self { state } = unsafe { self.get_unchecked_mut() };
loop { loop {
match this { match state {
FlattenFuture::First(fut1) => { State::First(fut1) => {
let fut2 = ready!(unsafe { Pin::new_unchecked(fut1) }.poll(cx)).into_future(); let fut2 = ready!(unsafe { Pin::new_unchecked(fut1) }.poll(cx)).into_future();
*this = FlattenFuture::Second(fut2); *state = State::Second(fut2);
} }
FlattenFuture::Second(fut2) => { State::Second(fut2) => {
let v = ready!(unsafe { Pin::new_unchecked(fut2) }.poll(cx)); let v = ready!(unsafe { Pin::new_unchecked(fut2) }.poll(cx));
*this = FlattenFuture::Empty; *state = State::Empty;
return Poll::Ready(v); return Poll::Ready(v);
} }
FlattenFuture::Empty => unreachable!(), State::Empty => panic!("polled a completed future"),
} }
} }
} }