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use super::File;
use std::future::Future;
use std::io;
use std::pin::Pin;
use std::task::Context;
use std::task::Poll;
/// Future returned by `File::try_clone`.
///
/// Clones a file handle into two file handles.
///
/// # Panics
///
/// Will panic if polled after returning an item or error.
#[derive(Debug)]
#[must_use = "futures do nothing unless you `.await` or poll them"]
pub struct CloneFuture {
file: Option<File>,
}
impl CloneFuture {
pub(crate) fn new(file: File) -> Self {
Self { file: Some(file) }
}
}
impl Future for CloneFuture {
type Output = Result<(File, File), (File, io::Error)>;
fn poll(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<Self::Output> {
let inner_self = Pin::get_mut(self);
inner_self
.file
.as_mut()
.expect("Cannot poll `CloneFuture` after it resolves")
.poll_try_clone()
.map(|inner| inner.map(|cloned| (inner_self.file.take().unwrap(), cloned)))
.map_err(|err| (inner_self.file.take().unwrap(), err))
}
}
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