diff options
Diffstat (limited to 'third_party/rust/futures-0.1.31/src/resultstream.rs')
-rw-r--r-- | third_party/rust/futures-0.1.31/src/resultstream.rs | 46 |
1 files changed, 46 insertions, 0 deletions
diff --git a/third_party/rust/futures-0.1.31/src/resultstream.rs b/third_party/rust/futures-0.1.31/src/resultstream.rs new file mode 100644 index 0000000000..23a99819bd --- /dev/null +++ b/third_party/rust/futures-0.1.31/src/resultstream.rs @@ -0,0 +1,46 @@ +// This should really be in the stream module, +// but `pub(crate)` isn't available until Rust 1.18, +// and pre-1.18 there isn't a really good way to have a sub-module +// available to the crate, but not without it. +use core::marker::PhantomData; + +use {Poll, Async}; +use stream::Stream; + + +/// A stream combinator used to convert a `Stream<Item=T,Error=E>` +/// to a `Stream<Item=Result<T,E>>`. +/// +/// A poll on this stream will never return an `Err`. As such the +/// actual error type is parameterized, so it can match whatever error +/// type is needed. +/// +/// This structure is produced by the `Stream::results` method. +#[derive(Debug)] +#[must_use = "streams do nothing unless polled"] +pub struct Results<S: Stream, E> { + inner: S, + phantom: PhantomData<E> +} + +pub fn new<S, E>(s: S) -> Results<S, E> where S: Stream { + Results { + inner: s, + phantom: PhantomData + } +} + +impl<S: Stream, E> Stream for Results<S, E> { + type Item = Result<S::Item, S::Error>; + type Error = E; + + fn poll(&mut self) -> Poll<Option<Result<S::Item, S::Error>>, E> { + match self.inner.poll() { + Ok(Async::Ready(Some(item))) => Ok(Async::Ready(Some(Ok(item)))), + Err(e) => Ok(Async::Ready(Some(Err(e)))), + Ok(Async::Ready(None)) => Ok(Async::Ready(None)), + Ok(Async::NotReady) => Ok(Async::NotReady) + } + } +} + |