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use futures::{Stream, StreamExt};
use futures_concurrency::stream::Merge;
#[derive(Debug)]
pub enum MergedEvent<E> {
Dora(super::Event),
External(E),
}
pub enum Either<A, B> {
First(A),
Second(B),
}
impl<A> Either<A, A> {
pub fn flatten(self) -> A {
match self {
Either::First(a) => a,
Either::Second(a) => a,
}
}
}
// TODO: use impl trait return type once stable
pub trait MergeExternal<'a, E> {
type Item;
fn merge_external(
self,
external_events: impl Stream<Item = E> + Unpin + 'a,
) -> Box<dyn Stream<Item = Self::Item> + Unpin + 'a>;
}
pub trait MergeExternalSend<'a, E> {
type Item;
fn merge_external_send(
self,
external_events: impl Stream<Item = E> + Unpin + Send + 'a,
) -> Box<dyn Stream<Item = Self::Item> + Unpin + Send + 'a>;
}
impl<'a, E> MergeExternal<'a, E> for super::EventStream
where
E: 'static,
{
type Item = MergedEvent<E>;
fn merge_external(
self,
external_events: impl Stream<Item = E> + Unpin + 'a,
) -> Box<dyn Stream<Item = Self::Item> + Unpin + 'a> {
let dora = self.map(MergedEvent::Dora);
let external = external_events.map(MergedEvent::External);
Box::new((dora, external).merge())
}
}
impl<'a, E> MergeExternalSend<'a, E> for super::EventStream
where
E: 'static,
{
type Item = MergedEvent<E>;
fn merge_external_send(
self,
external_events: impl Stream<Item = E> + Unpin + Send + 'a,
) -> Box<dyn Stream<Item = Self::Item> + Unpin + Send + 'a> {
let dora = self.map(MergedEvent::Dora);
let external = external_events.map(MergedEvent::External);
Box::new((dora, external).merge())
}
}
impl<'a, E, F, S> MergeExternal<'a, F> for S
where
S: Stream<Item = MergedEvent<E>> + Unpin + 'a,
E: 'a,
F: 'a,
{
type Item = MergedEvent<Either<E, F>>;
fn merge_external(
self,
external_events: impl Stream<Item = F> + Unpin + 'a,
) -> Box<dyn Stream<Item = Self::Item> + Unpin + 'a> {
let first = self.map(|e| match e {
MergedEvent::Dora(d) => MergedEvent::Dora(d),
MergedEvent::External(e) => MergedEvent::External(Either::First(e)),
});
let second = external_events.map(|e| MergedEvent::External(Either::Second(e)));
Box::new((first, second).merge())
}
}
impl<'a, E, F, S> MergeExternalSend<'a, F> for S
where
S: Stream<Item = MergedEvent<E>> + Unpin + Send + 'a,
E: 'a,
F: 'a,
{
type Item = MergedEvent<Either<E, F>>;
fn merge_external_send(
self,
external_events: impl Stream<Item = F> + Unpin + Send + 'a,
) -> Box<dyn Stream<Item = Self::Item> + Unpin + Send + 'a> {
let first = self.map(|e| match e {
MergedEvent::Dora(d) => MergedEvent::Dora(d),
MergedEvent::External(e) => MergedEvent::External(Either::First(e)),
});
let second = external_events.map(|e| MergedEvent::External(Either::Second(e)));
Box::new((first, second).merge())
}
}
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