add TryWideband trait to similar to TryBroadband

Signed-off-by: Jason Volk <jason@zemos.net>

src/core/utils/stream/mod.rs

@@ -9,6 +9,7 @@ mod tools;
 mod try_broadband;
 mod try_ready;
 mod try_tools;
+mod try_wideband;
 mod wideband;
 
 pub use band::{
@@ -25,4 +26,5 @@ pub use tools::Tools;
 pub use try_broadband::TryBroadbandExt;
 pub use try_ready::TryReadyExt;
 pub use try_tools::TryTools;
+pub use try_wideband::TryWidebandExt;
 pub use wideband::WidebandExt;

src/core/utils/stream/try_wideband.rs

@@ -0,0 +1,57 @@
+//! Synchronous combinator extensions to futures::TryStream
+
+use futures::{TryFuture, TryStream, TryStreamExt};
+
+use super::automatic_width;
+use crate::Result;
+
+/// Concurrency extensions to augment futures::TryStreamExt. wide_ combinators
+/// produce in-order results
+pub trait TryWidebandExt<T, E>
+where
+	Self: TryStream<Ok = T, Error = E, Item = Result<T, E>> + Send + Sized,
+{
+	fn widen_and_then<U, F, Fut, N>(
+		self,
+		n: N,
+		f: F,
+	) -> impl TryStream<Ok = U, Error = E, Item = Result<U, E>> + Send
+	where
+		N: Into<Option<usize>>,
+		F: Fn(Self::Ok) -> Fut + Send,
+		Fut: TryFuture<Ok = U, Error = E, Output = Result<U, E>> + Send,
+		U: Send;
+
+	fn wide_and_then<U, F, Fut>(
+		self,
+		f: F,
+	) -> impl TryStream<Ok = U, Error = E, Item = Result<U, E>> + Send
+	where
+		F: Fn(Self::Ok) -> Fut + Send,
+		Fut: TryFuture<Ok = U, Error = E, Output = Result<U, E>> + Send,
+		U: Send,
+	{
+		self.widen_and_then(None, f)
+	}
+}
+
+impl<T, E, S> TryWidebandExt<T, E> for S
+where
+	S: TryStream<Ok = T, Error = E, Item = Result<T, E>> + Send + Sized,
+	E: Send,
+{
+	fn widen_and_then<U, F, Fut, N>(
+		self,
+		n: N,
+		f: F,
+	) -> impl TryStream<Ok = U, Error = E, Item = Result<U, E>> + Send
+	where
+		N: Into<Option<usize>>,
+		F: Fn(Self::Ok) -> Fut + Send,
+		Fut: TryFuture<Ok = U, Error = E, Output = Result<U, E>> + Send,
+		U: Send,
+	{
+		self.map_ok(f)
+			.try_buffered(n.into().unwrap_or_else(automatic_width))
+	}
+}