forked from ROMEO/nexosim
54 lines
1.4 KiB
Rust
54 lines
1.4 KiB
Rust
//! Futures and future-related functions.
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#![allow(unused)]
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use std::future::Future;
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use std::pin::Pin;
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use std::task::{Context, Poll};
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/// An owned future which sequentially polls a collection of futures.
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///
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/// The outputs of the futures, if any, are ignored. For simplicity, the
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/// implementation assumes that the futures are `Unpin`. This constrained could
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/// be relaxed if necessary by using something else than a `Vec` to ensure that
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/// each future is pinned (a `Vec` is not suitable for pinning because it may
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/// move its items when dropped).
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pub(crate) struct SeqFuture<F> {
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inner: Vec<F>,
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idx: usize,
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}
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impl<F> SeqFuture<F> {
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/// Creates a new, empty `SeqFuture`.
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pub(crate) fn new() -> Self {
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Self {
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inner: Vec::new(),
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idx: 0,
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}
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}
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/// Appends a future.
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pub(crate) fn push(&mut self, future: F) {
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self.inner.push(future);
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}
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}
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impl<F: Future + Unpin> Future for SeqFuture<F> {
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type Output = ();
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fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
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let this = &mut *self;
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// The below will panic due to out of bound access when polling after
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// completion: this is intentional.
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while Pin::new(&mut this.inner[this.idx]).poll(cx).is_ready() {
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this.idx += 1;
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if this.idx == this.inner.len() {
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return Poll::Ready(());
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}
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}
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Poll::Pending
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}
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}
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