Wrap hyper's GaiResolver in a newtype

This allows to implement the Default trait for the GaiResolver.
Using this newtype instead of hyper's GaiResolver permits to have a
uniform interface where RestClient/Builder require for resolver
types to implement the Default trait for internal default resolver
construction.

Author: 2000andrea

src/lib.rs

@@ -52,6 +52,9 @@ use hyper_tls::HttpsConnector;
 #[cfg(feature = "rustls")]
 use hyper_rustls::{HttpsConnector, HttpsConnectorBuilder};
 
+use resolvers::GaiResolver;
+
+pub mod resolvers;
 #[cfg(feature = "blocking")]
 pub mod blocking;
 
@@ -121,7 +124,7 @@ impl<T> Deref for Response<T> {
 }
 
 /// REST client to make HTTP GET and POST requests.
-pub struct RestClient<R = dns::GaiResolver> {
+pub struct RestClient<R = GaiResolver> {
     client: HyperClient<R>,
     baseurl: url::Url,
     auth: Option<String>,
@@ -170,7 +173,7 @@ pub enum Error {
 }
 
 /// Builder for `RestClient`
-pub struct Builder<R = dns::GaiResolver> {
+pub struct Builder<R = GaiResolver> {
     /// Request timeout
     timeout: Duration,
 

src/resolvers.rs

@@ -0,0 +1,47 @@
+use core::task::{Context, Poll};
+
+use hyper::client::connect::dns::{self, GaiResolver as HyperGaiResolver};
+use hyper::service::Service;
+
+/// Newtype wrapper around hyper's GaiResolver to provide Default
+/// trait implementation
+#[derive(Clone, Debug)]
+pub struct GaiResolver(HyperGaiResolver);
+
+impl GaiResolver {
+    pub fn new() -> Self {
+        Self::default()
+    }
+}
+
+impl From<HyperGaiResolver> for GaiResolver {
+    fn from(gai: HyperGaiResolver) -> Self {
+        Self(gai)
+    }
+}
+
+impl Into<HyperGaiResolver> for GaiResolver {
+    fn into(self) -> HyperGaiResolver {
+        self.0
+    }
+}
+
+impl Default for GaiResolver {
+    fn default() -> Self {
+        Self(HyperGaiResolver::new())
+    }
+}
+
+impl Service<dns::Name> for GaiResolver {
+    type Response = <HyperGaiResolver as Service<dns::Name>>::Response;
+    type Error = <HyperGaiResolver as Service<dns::Name>>::Error;
+    type Future = <HyperGaiResolver as Service<dns::Name>>::Future;
+
+    fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
+        self.0.poll_ready(cx)
+    }
+
+    fn call(&mut self, name: dns::Name) -> Self::Future {
+        self.0.call(name)
+    }
+}