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Anonymous function to avoid type issues

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razican 2019-11-11 11:25:50 +01:00
parent 79bbf4938d
commit 0c37d4af10
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1 changed files with 21 additions and 12 deletions
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33
src/stream/stream/merge.rs
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@ -5,6 +5,7 @@ use pin_project_lite::pin_project;
use crate::prelude::*;
use crate::stream::Fuse;
use crate::utils;
pin_project! {
/// A stream that merges two other streams into a single stream.
@ -43,19 +44,27 @@ where
fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
let this = self.project();
let (first, second) = if (utils::random(1) == 1) {
(this.left, this.right)
if utils::random(1) == 1 {
poll_next_in_order(cx, this.left, this.right)
} else {
(this.right, this.left)
};
match first.poll_next(cx) {
Poll::Ready(Some(item)) => Poll::Ready(Some(item)),
Poll::Ready(None) => second.poll_next(cx),
Poll::Pending => match second.poll_next(cx) {
Poll::Ready(Some(item)) => Poll::Ready(Some(item)),
Poll::Ready(None) => Poll::Pending,
Poll::Pending => Poll::Pending,
},
poll_next_in_order(cx, this.right, this.left)
}
}
}
/// Pools the next item, trying in order, first the first item, then the second one.
fn poll_next_in_order<F, S, T>(cx: &mut Context<'_>, first: F, second: S) -> Poll<Option<T>>
where
F: Stream<Item = T>,
S: Stream<Item = T>,
{
match first.poll_next(cx) {
Poll::Ready(Some(item)) => Poll::Ready(Some(item)),
Poll::Ready(None) => second.poll_next(cx),
Poll::Pending => match second.poll_next(cx) {
Poll::Ready(Some(item)) => Poll::Ready(Some(item)),
Poll::Ready(None) => Poll::Pending,
Poll::Pending => Poll::Pending,
},
}
}