| use core::marker; |
| |
| use stream::Stream; |
| use {Poll, Async}; |
| |
| /// A stream which contains no elements. |
| /// |
| /// This stream can be created with the `stream::empty` function. |
| #[derive(Debug)] |
| #[must_use = "streams do nothing unless polled"] |
| pub struct Empty<T, E> { |
| _data: marker::PhantomData<(T, E)>, |
| } |
| |
| /// Creates a stream which contains no elements. |
| /// |
| /// The returned stream will always return `Ready(None)` when polled. |
| pub fn empty<T, E>() -> Empty<T, E> { |
| Empty { _data: marker::PhantomData } |
| } |
| |
| impl<T, E> Stream for Empty<T, E> { |
| type Item = T; |
| type Error = E; |
| |
| fn poll(&mut self) -> Poll<Option<Self::Item>, Self::Error> { |
| Ok(Async::Ready(None)) |
| } |
| } |