60 lines
1.4 KiB
Rust
60 lines
1.4 KiB
Rust
use super::assert_sink;
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use crate::never::Never;
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use core::marker::PhantomData;
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use core::pin::Pin;
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use futures_core::task::{Context, Poll};
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use futures_sink::Sink;
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/// Sink for the [`drain`] function.
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#[derive(Debug)]
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#[must_use = "sinks do nothing unless polled"]
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pub struct Drain<T> {
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marker: PhantomData<T>,
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}
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/// Create a sink that will just discard all items given to it.
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///
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/// Similar to [`io::Sink`](::std::io::Sink).
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///
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/// # Examples
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///
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/// ```
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/// # futures::executor::block_on(async {
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/// use futures::sink::{self, SinkExt};
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///
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/// let mut drain = sink::drain();
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/// drain.send(5).await?;
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/// # Ok::<(), futures::never::Never>(()) }).unwrap();
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/// ```
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pub fn drain<T>() -> Drain<T> {
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assert_sink::<T, Never, _>(Drain { marker: PhantomData })
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}
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impl<T> Unpin for Drain<T> {}
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impl<T> Clone for Drain<T> {
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fn clone(&self) -> Self {
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drain()
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}
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}
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impl<T> Sink<T> for Drain<T> {
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type Error = Never;
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fn poll_ready(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
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Poll::Ready(Ok(()))
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}
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fn start_send(self: Pin<&mut Self>, _item: T) -> Result<(), Self::Error> {
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Ok(())
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}
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fn poll_flush(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
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Poll::Ready(Ok(()))
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}
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fn poll_close(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
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Poll::Ready(Ok(()))
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}
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}
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