Improve the code readability of the chat example (#1253)

Author: Ashley

examples/chat.rs

@@ -55,7 +55,11 @@ use libp2p::{
     Swarm,
     NetworkBehaviour,
     identity,
-    tokio_codec::{FramedRead, LinesCodec}
+    tokio_codec::{FramedRead, LinesCodec},
+    tokio_io::{AsyncRead, AsyncWrite},
+    floodsub::{self, Floodsub, FloodsubEvent},
+    mdns::{Mdns, MdnsEvent},
+    swarm::NetworkBehaviourEventProcess
 };
 
 fn main() {
@@ -70,25 +74,25 @@ fn main() {
     let transport = libp2p::build_development_transport(local_key);
 
     // Create a Floodsub topic
-    let floodsub_topic = libp2p::floodsub::TopicBuilder::new("chat").build();
+    let floodsub_topic = floodsub::TopicBuilder::new("chat").build();
 
     // We create a custom network behaviour that combines floodsub and mDNS.
     // In the future, we want to improve libp2p to make this easier to do.
     #[derive(NetworkBehaviour)]
-    struct MyBehaviour<TSubstream: libp2p::tokio_io::AsyncRead + libp2p::tokio_io::AsyncWrite> {
-        floodsub: libp2p::floodsub::Floodsub<TSubstream>,
-        mdns: libp2p::mdns::Mdns<TSubstream>,
+    struct MyBehaviour<TSubstream: AsyncRead + AsyncWrite> {
+        floodsub: Floodsub<TSubstream>,
+        mdns: Mdns<TSubstream>,
     }
 
-    impl<TSubstream: libp2p::tokio_io::AsyncRead + libp2p::tokio_io::AsyncWrite> libp2p::swarm::NetworkBehaviourEventProcess<libp2p::mdns::MdnsEvent> for MyBehaviour<TSubstream> {
-        fn inject_event(&mut self, event: libp2p::mdns::MdnsEvent) {
+    impl<TSubstream: AsyncRead + AsyncWrite> NetworkBehaviourEventProcess<MdnsEvent> for MyBehaviour<TSubstream> {
+        fn inject_event(&mut self, event: MdnsEvent) {
             match event {
-                libp2p::mdns::MdnsEvent::Discovered(list) => {
+                MdnsEvent::Discovered(list) => {
                     for (peer, _) in list {
                         self.floodsub.add_node_to_partial_view(peer);
                     }
                 },
-                libp2p::mdns::MdnsEvent::Expired(list) => {
+                MdnsEvent::Expired(list) => {
                     for (peer, _) in list {
                         if !self.mdns.has_node(&peer) {
                             self.floodsub.remove_node_from_partial_view(&peer);
@@ -99,10 +103,10 @@ fn main() {
         }
     }
 
-    impl<TSubstream: libp2p::tokio_io::AsyncRead + libp2p::tokio_io::AsyncWrite> libp2p::swarm::NetworkBehaviourEventProcess<libp2p::floodsub::FloodsubEvent> for MyBehaviour<TSubstream> {
+    impl<TSubstream: AsyncRead + AsyncWrite> NetworkBehaviourEventProcess<FloodsubEvent> for MyBehaviour<TSubstream> {
         // Called when `floodsub` produces an event.
-        fn inject_event(&mut self, message: libp2p::floodsub::FloodsubEvent) {
-            if let libp2p::floodsub::FloodsubEvent::Message(message) = message {
+        fn inject_event(&mut self, message: FloodsubEvent) {
+            if let FloodsubEvent::Message(message) = message {
                 println!("Received: '{:?}' from {:?}", String::from_utf8_lossy(&message.data), message.source);
             }
         }
@@ -111,12 +115,12 @@ fn main() {
     // Create a Swarm to manage peers and events
     let mut swarm = {
         let mut behaviour = MyBehaviour {
-            floodsub: libp2p::floodsub::Floodsub::new(local_peer_id.clone()),
-            mdns: libp2p::mdns::Mdns::new().expect("Failed to create mDNS service"),
+            floodsub: Floodsub::new(local_peer_id.clone()),
+            mdns: Mdns::new().expect("Failed to create mDNS service"),
         };
 
         behaviour.floodsub.subscribe(floodsub_topic.clone());
-        libp2p::Swarm::new(transport, behaviour, local_peer_id)
+        Swarm::new(transport, behaviour, local_peer_id)
     };
 
     // Reach out to another node if specified
@@ -138,7 +142,7 @@ fn main() {
     let mut framed_stdin = FramedRead::new(stdin, LinesCodec::new());
 
     // Listen on all interfaces and whatever port the OS assigns
-    libp2p::Swarm::listen_on(&mut swarm, "/ip4/0.0.0.0/tcp/0".parse().unwrap()).unwrap();
+    Swarm::listen_on(&mut swarm, "/ip4/0.0.0.0/tcp/0".parse().unwrap()).unwrap();
 
     // Kick it off
     let mut listening = false;