add streamext

Author: yoshuawuyts

src/stream/mod.rs

@@ -50,9 +50,11 @@
 pub use chain::Chain;
 pub use into_stream::IntoStream;
 pub use merge::Merge;
+pub use stream_ext::StreamExt;
 pub use zip::Zip;
 
 pub(crate) mod chain;
 mod into_stream;
 pub(crate) mod merge;
+mod stream_ext;
 pub(crate) mod zip;

src/stream/stream_ext.rs

@@ -0,0 +1,26 @@
+use crate::stream::{IntoStream, Merge};
+use futures_core::Stream;
+
+use super::merge::tuple::Merge2;
+
+/// An extension trait for the `Stream` trait.
+pub trait StreamExt: Stream {
+    /// Combines two streams into a single stream of all their outputs.
+    fn merge<T, S2>(self, other: S2) -> Merge2<T, Self, S2::IntoStream>
+    where
+        Self: Stream<Item = T> + Sized,
+        S2: IntoStream<Item = T>;
+}
+
+impl<S1> StreamExt for S1
+where
+    S1: Stream,
+{
+    fn merge<T, S2>(self, other: S2) -> Merge2<T, S1, S2::IntoStream>
+    where
+        S1: Stream<Item = T>,
+        S2: IntoStream<Item = T>,
+    {
+        Merge::merge((self, other))
+    }
+}