Abstractify the Listener abstractions further

components/net_traits/lib.rs

@@ -187,6 +187,13 @@ pub trait FetchTaskTarget {
     fn process_response_eof(&mut self, response: &response::Response);
 }
 
+pub trait FetchResponseListener {
+    fn process_request_body(&mut self);
+    fn process_request_eof(&mut self);
+    fn process_response(&mut self, metadata: Result<Metadata, NetworkError>);
+    fn process_response_eof(&mut self, response: Result<Vec<u8>, NetworkError>);
+}
+
 impl FetchTaskTarget for IpcSender<FetchResponseMsg> {
     fn process_request_body(&mut self, _: &request::Request) {
         let _ = self.send(FetchResponseMsg::ProcessRequestBody);
@@ -217,6 +224,10 @@ impl FetchTaskTarget for IpcSender<FetchResponseMsg> {
     }
 }
 
+pub trait Action<Listener> {
+    fn process(self, listener: &mut Listener);
+}
+
 /// A listener for asynchronous network events. Cancelling the underlying request is unsupported.
 pub trait AsyncResponseListener {
     /// The response headers for a request have been received.
@@ -241,9 +252,9 @@ pub enum ResponseAction {
     ResponseComplete(Result<(), NetworkError>)
 }
 
-impl ResponseAction {
+impl<T: AsyncResponseListener> Action<T> for ResponseAction {
     /// Execute the default action on a provided listener.
-    pub fn process(self, listener: &mut AsyncResponseListener) {
+    fn process(self, listener: &mut T) {
         match self {
             ResponseAction::HeadersAvailable(m) => listener.headers_available(m),
             ResponseAction::DataAvailable(d) => listener.data_available(d),
@@ -252,6 +263,18 @@ impl ResponseAction {
     }
 }
 
+impl<T: FetchResponseListener> Action<T> for FetchResponseMsg {
+    /// Execute the default action on a provided listener.
+    fn process(self, listener: &mut T) {
+        match self {
+            FetchResponseMsg::ProcessRequestBody => listener.process_request_body(),
+            FetchResponseMsg::ProcessRequestEOF => listener.process_request_eof(),
+            FetchResponseMsg::ProcessResponse(meta) => listener.process_response(meta),
+            FetchResponseMsg::ProcessResponseEOF(data) => listener.process_response_eof(data),
+        }
+    }
+}
+
 /// A target for async networking events. Commonly used to dispatch a runnable event to another
 /// thread storing the wrapped closure for later execution.
 #[derive(Deserialize, Serialize)]

components/script/dom/htmllinkelement.rs

@@ -227,7 +227,7 @@ impl HTMLLinkElement {
                     sender: action_sender,
                 };
                 ROUTER.add_route(action_receiver.to_opaque(), box move |message| {
-                    listener.notify(message.to().unwrap());
+                    listener.notify_action(message.to().unwrap());
                 });
 
                 if self.parser_inserted.get() {

components/script/dom/htmlmediaelement.rs

@@ -484,7 +484,7 @@ impl HTMLMediaElement {
                 sender: action_sender,
             };
             ROUTER.add_route(action_receiver.to_opaque(), box move |message| {
-                listener.notify(message.to().unwrap());
+                listener.notify_action(message.to().unwrap());
             });
 
             // FIXME: we're supposed to block the load event much earlier than now

components/script/dom/htmlscriptelement.rs

@@ -314,7 +314,7 @@ impl HTMLScriptElement {
                     sender: action_sender,
                 };
                 ROUTER.add_route(action_receiver.to_opaque(), box move |message| {
-                    listener.notify(message.to().unwrap());
+                    listener.notify_action(message.to().unwrap());
                 });
 
                 doc.load_async(LoadType::Script(url), response_target);

components/script/dom/xmlhttprequest.rs

@@ -302,7 +302,7 @@ impl XMLHttpRequest {
             sender: action_sender,
         };
         ROUTER.add_route(action_receiver.to_opaque(), box move |message| {
-            listener.notify(message.to().unwrap());
+            listener.notify_action(message.to().unwrap());
         });
         core_resource_thread.send(Load(load_data, LoadConsumer::Listener(response_target), None)).unwrap();
     }

components/script/network_listener.rs

@@ -2,7 +2,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-use net_traits::{AsyncResponseListener, ResponseAction};
+use net_traits::{Action, AsyncResponseListener, ResponseAction};
 use script_runtime::ScriptThreadEventCategory::NetworkEvent;
 use script_runtime::{CommonScriptMsg, ScriptChan};
 use script_thread::Runnable;
@@ -10,13 +10,13 @@ use std::sync::{Arc, Mutex};
 
 /// An off-thread sink for async network event runnables. All such events are forwarded to
 /// a target thread, where they are invoked on the provided context object.
-pub struct NetworkListener<T: AsyncResponseListener + PreInvoke + Send + 'static> {
-    pub context: Arc<Mutex<T>>,
+pub struct NetworkListener<Listener: PreInvoke + Send + 'static> {
+    pub context: Arc<Mutex<Listener>>,
     pub script_chan: Box<ScriptChan + Send>,
 }
 
-impl<T: AsyncResponseListener + PreInvoke + Send + 'static> NetworkListener<T> {
-    pub fn notify(&self, action: ResponseAction) {
+impl<Listener: PreInvoke + Send + 'static> NetworkListener<Listener> {
+    pub fn notify<A: Action<Listener>+Send+'static>(&self, action: A) {
         if let Err(err) = self.script_chan.send(CommonScriptMsg::RunnableMsg(NetworkEvent, box ListenerRunnable {
             context: self.context.clone(),
             action: action,
@@ -26,6 +26,13 @@ impl<T: AsyncResponseListener + PreInvoke + Send + 'static> NetworkListener<T> {
     }
 }
 
+// helps type inference
+impl<Listener: AsyncResponseListener + PreInvoke + Send + 'static> NetworkListener<Listener> {
+    pub fn notify_action(&self, action: ResponseAction) {
+        self.notify(action);
+    }
+}
+
 /// A gating mechanism that runs before invoking the runnable on the target thread.
 /// If the `should_invoke` method returns false, the runnable is discarded without
 /// being invoked.
@@ -36,13 +43,13 @@ pub trait PreInvoke {
 }
 
 /// A runnable for moving the async network events between threads.
-struct ListenerRunnable<T: AsyncResponseListener + PreInvoke + Send> {
-    context: Arc<Mutex<T>>,
-    action: ResponseAction,
+struct ListenerRunnable<A: Action<Listener>+Send+'static, Listener: PreInvoke + Send> {
+    context: Arc<Mutex<Listener>>,
+    action: A,
 }
 
-impl<T: AsyncResponseListener + PreInvoke + Send> Runnable for ListenerRunnable<T> {
-    fn handler(self: Box<ListenerRunnable<T>>) {
+impl<A: Action<Listener>+Send+'static, Listener: PreInvoke + Send> Runnable for ListenerRunnable<A, Listener> {
+    fn handler(self: Box<ListenerRunnable<A, Listener>>) {
         let this = *self;
         let mut context = this.context.lock().unwrap();
         if context.should_invoke() {

components/script/script_thread.rs

@@ -1947,7 +1947,7 @@ impl ScriptThread {
             script_chan: self.chan.clone(),
         };
         ROUTER.add_route(action_receiver.to_opaque(), box move |message| {
-            listener.notify(message.to().unwrap());
+            listener.notify_action(message.to().unwrap());
         });
         let response_target = AsyncResponseTarget {
             sender: action_sender,