add broad_flat_map

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

src/core/utils/stream/broadband.rs

@@ -35,6 +35,13 @@ where
 		Fut: Future<Output = Option<U>> + Send,
 		U: Send;
 
+	fn broadn_flat_map<F, Fut, U, N>(self, n: N, f: F) -> impl Stream<Item = U> + Send
+	where
+		N: Into<Option<usize>>,
+		F: Fn(Item) -> Fut + Send,
+		Fut: Stream<Item = U> + Send + Unpin,
+		U: Send;
+
 	fn broadn_then<F, Fut, U, N>(self, n: N, f: F) -> impl Stream<Item = U> + Send
 	where
 		N: Into<Option<usize>>,
@@ -70,6 +77,16 @@ where
 		self.broadn_filter_map(None, f)
 	}
 
+	#[inline]
+	fn broad_flat_map<F, Fut, U>(self, f: F) -> impl Stream<Item = U> + Send
+	where
+		F: Fn(Item) -> Fut + Send,
+		Fut: Stream<Item = U> + Send + Unpin,
+		U: Send,
+	{
+		self.broadn_flat_map(None, f)
+	}
+
 	#[inline]
 	fn broad_then<F, Fut, U>(self, f: F) -> impl Stream<Item = U> + Send
 	where
@@ -122,6 +139,17 @@ where
 			.ready_filter_map(identity)
 	}
 
+	#[inline]
+	fn broadn_flat_map<F, Fut, U, N>(self, n: N, f: F) -> impl Stream<Item = U> + Send
+	where
+		N: Into<Option<usize>>,
+		F: Fn(Item) -> Fut + Send,
+		Fut: Stream<Item = U> + Send + Unpin,
+		U: Send,
+	{
+		self.flat_map_unordered(n.into().unwrap_or_else(automatic_width), f)
+	}
+
 	#[inline]
 	fn broadn_then<F, Fut, U, N>(self, n: N, f: F) -> impl Stream<Item = U> + Send
 	where