forked from mirror/async-std
45 lines
873 B
Rust
45 lines
873 B
Rust
use std::marker::PhantomData;
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use std::pin::Pin;
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use crate::stream::Stream;
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use crate::task::{Context, Poll};
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/// Creates a stream that doesn't yield any items.
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///
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/// # Examples
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///
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/// ```
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/// # async_std::task::block_on(async {
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/// #
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/// use async_std::prelude::*;
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/// use async_std::stream;
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///
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/// let mut s = stream::empty::<i32>();
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///
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/// assert_eq!(s.next().await, None);
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/// #
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/// # })
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/// ```
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pub fn empty<T>() -> Empty<T> {
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Empty {
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_marker: PhantomData,
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}
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}
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/// A stream that doesn't yield any items.
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///
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/// This stream is constructed by the [`empty`] function.
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///
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/// [`empty`]: fn.empty.html
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#[derive(Debug)]
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pub struct Empty<T> {
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_marker: PhantomData<T>,
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}
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impl<T> Stream for Empty<T> {
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type Item = T;
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fn poll_next(self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<Option<Self::Item>> {
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Poll::Ready(None)
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}
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}
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