From c1a749b01a6f92777fa9450f72d82f89e4a04b65 Mon Sep 17 00:00:00 2001
From: Platon Floria <platon.floria@gmail.com>
Date: Thu, 10 Aug 2023 20:39:24 +0800
Subject: [PATCH] Add wasm support to transports::Either

---
 src/transports/either.rs | 76 +++++++++++++++++++++++++++++++++-------
 1 file changed, 63 insertions(+), 13 deletions(-)

diff --git a/src/transports/either.rs b/src/transports/either.rs
index d86c2fa8..50d103a2 100644
--- a/src/transports/either.rs
+++ b/src/transports/either.rs
@@ -1,6 +1,9 @@
 //! A strongly-typed transport alternative.
 
 use crate::{api, error, rpc, BatchTransport, DuplexTransport, RequestId, Transport};
+#[cfg(feature = "wasm")]
+use futures::{future::LocalBoxFuture as BoxFuture, stream::LocalBoxStream as BoxStream};
+#[cfg(not(feature = "wasm"))]
 use futures::{
     future::{BoxFuture, FutureExt},
     stream::{BoxStream, StreamExt},
@@ -20,12 +23,21 @@ pub enum Either<A, B> {
     Right(B),
 }
 
+#[cfg(not(feature = "wasm"))]
+trait Out: futures::Future<Output = error::Result<rpc::Value>> + 'static + Send {}
+#[cfg(not(feature = "wasm"))]
+impl<T> Out for T where T: futures::Future<Output = error::Result<rpc::Value>> + 'static + Send {}
+#[cfg(feature = "wasm")]
+trait Out: futures::Future<Output = error::Result<rpc::Value>> + 'static {}
+#[cfg(feature = "wasm")]
+impl<T> Out for T where T: futures::Future<Output = error::Result<rpc::Value>> + 'static {}
+
 impl<A, B, AOut, BOut> Transport for Either<A, B>
 where
     A: Transport<Out = AOut>,
     B: Transport<Out = BOut>,
-    AOut: futures::Future<Output = error::Result<rpc::Value>> + 'static + Send,
-    BOut: futures::Future<Output = error::Result<rpc::Value>> + 'static + Send,
+    AOut: Out,
+    BOut: Out,
 {
     type Out = BoxFuture<'static, error::Result<rpc::Value>>;
 
@@ -37,21 +49,36 @@ where
     }
 
     fn send(&self, id: RequestId, request: rpc::Call) -> Self::Out {
+        #[cfg(not(feature = "wasm"))]
         match *self {
             Self::Left(ref a) => a.send(id, request).boxed(),
             Self::Right(ref b) => b.send(id, request).boxed(),
         }
+        #[cfg(feature = "wasm")]
+        match *self {
+            Self::Left(ref a) => Box::pin(a.send(id, request)),
+            Self::Right(ref b) => Box::pin(b.send(id, request)),
+        }
     }
 }
 
+#[cfg(not(feature = "wasm"))]
+trait Batch: futures::Future<Output = error::Result<Vec<error::Result<rpc::Value>>>> + 'static + Send {}
+#[cfg(not(feature = "wasm"))]
+impl<T> Batch for T where T: futures::Future<Output = error::Result<Vec<error::Result<rpc::Value>>>> + 'static + Send {}
+#[cfg(feature = "wasm")]
+trait Batch: futures::Future<Output = error::Result<Vec<error::Result<rpc::Value>>>> + 'static {}
+#[cfg(feature = "wasm")]
+impl<T> Batch for T where T: futures::Future<Output = error::Result<Vec<error::Result<rpc::Value>>>> + 'static {}
+
 impl<A, B, ABatch, BBatch> BatchTransport for Either<A, B>
 where
     A: BatchTransport<Batch = ABatch>,
     B: BatchTransport<Batch = BBatch>,
-    A::Out: 'static + Send,
-    B::Out: 'static + Send,
-    ABatch: futures::Future<Output = error::Result<Vec<error::Result<rpc::Value>>>> + 'static + Send,
-    BBatch: futures::Future<Output = error::Result<Vec<error::Result<rpc::Value>>>> + 'static + Send,
+    A::Out: Out,
+    B::Out: Out,
+    ABatch: Batch,
+    BBatch: Batch,
 {
     type Batch = BoxFuture<'static, error::Result<Vec<error::Result<rpc::Value>>>>;
 
@@ -59,28 +86,51 @@ where
     where
         T: IntoIterator<Item = (RequestId, rpc::Call)>,
     {
+        #[cfg(not(feature = "wasm"))]
         match *self {
             Self::Left(ref a) => a.send_batch(requests).boxed(),
             Self::Right(ref b) => b.send_batch(requests).boxed(),
         }
+        #[cfg(feature = "wasm")]
+        match *self {
+            Self::Left(ref a) => Box::pin(a.send_batch(requests)),
+            Self::Right(ref b) => Box::pin(b.send_batch(requests)),
+        }
     }
 }
 
+#[cfg(not(feature = "wasm"))]
+trait NotificationStream: futures::Stream<Item = rpc::Value> + 'static + Send {}
+#[cfg(not(feature = "wasm"))]
+impl<T> NotificationStream for T where T: futures::Stream<Item = rpc::Value> + 'static + Send {}
+#[cfg(feature = "wasm")]
+trait NotificationStream: futures::Stream<Item = rpc::Value> + 'static {}
+#[cfg(feature = "wasm")]
+impl<T> NotificationStream for T where T: futures::Stream<Item = rpc::Value> + 'static {}
+
 impl<A, B, AStream, BStream> DuplexTransport for Either<A, B>
 where
     A: DuplexTransport<NotificationStream = AStream>,
     B: DuplexTransport<NotificationStream = BStream>,
-    A::Out: 'static + Send,
-    B::Out: 'static + Send,
-    AStream: futures::Stream<Item = rpc::Value> + 'static + Send,
-    BStream: futures::Stream<Item = rpc::Value> + 'static + Send,
+    A::Out: Out,
+    B::Out: Out,
+    AStream: NotificationStream,
+    BStream: NotificationStream,
 {
     type NotificationStream = BoxStream<'static, rpc::Value>;
 
     fn subscribe(&self, id: api::SubscriptionId) -> error::Result<Self::NotificationStream> {
-        Ok(match *self {
-            Self::Left(ref a) => a.subscribe(id)?.boxed(),
-            Self::Right(ref b) => b.subscribe(id)?.boxed(),
+        Ok({
+            #[cfg(not(feature = "wasm"))]
+            match *self {
+                Self::Left(ref a) => a.subscribe(id)?.boxed(),
+                Self::Right(ref b) => b.subscribe(id)?.boxed(),
+            }
+            #[cfg(feature = "wasm")]
+            match *self {
+                Self::Left(ref a) => Box::pin(a.subscribe(id)?),
+                Self::Right(ref b) => Box::pin(b.subscribe(id)?),
+            }
         })
     }