Add an async server implementation for Yunq.

yunq/rust/src/codegen.rs

@@ -392,13 +392,116 @@ fn generate_server(interface: &Interface) -> TokenStream {
     }
 }
 
+fn generate_async_server_case(method: &Method) -> TokenStream {
+    let id = proc_macro2::Literal::u64_suffixed(method.number);
+    let name = ident(&method.name.to_case(Case::Snake));
+    let maybe_req = method.request.clone().map(|r| ident(&r));
+    let maybe_resp = method.response.clone().map(|r| ident(&r));
+    match (maybe_req, maybe_resp) {
+        (Some(req), Some(_)) => quote! {
+            #id => {
+                let req = #req::parse_from_request(byte_buffer, cap_buffer)?;
+                let resp = self.handler.#name(req).await?;
+                cap_buffer.resize(0, 0);
+                let resp_len = resp.serialize_as_request(0, byte_buffer, cap_buffer)?;
+                Ok(resp_len)
+            },
+        },
+        (Some(req), None) => quote! {
+            #id => {
+                let req = #req::parse_from_request(byte_buffer, cap_buffer)?;
+                self.handler.#name(req).await?;
+                cap_buffer.resize(0, 0);
+                // TODO: Implement serialization for EmptyMessage so this is less hacky.
+                yunq::message::serialize_error(byte_buffer, ZError::from(0));
+                Ok(0x10)
+            },
+        },
+        (None, Some(_)) => quote! {
+            #id => {
+                let resp = self.handler.#name().await?;
+                cap_buffer.resize(0, 0);
+                let resp_len = resp.serialize_as_request(0, byte_buffer, cap_buffer)?;
+                Ok(resp_len)
+            },
+        },
+        _ => unreachable!(),
+    }
+}
+
+fn generate_async_server_method(method: &Method) -> TokenStream {
+    let name = ident(&method.name.to_case(Case::Snake));
+    let maybe_req = method.request.clone().map(|r| ident(&r));
+    let maybe_resp = method.response.clone().map(|r| ident(&r));
+    match (maybe_req, maybe_resp) {
+        (Some(req), Some(resp)) => quote! {
+            fn #name (&self, req: #req) -> impl Future<Output= Result<#resp, ZError>> + Sync;
+        },
+        (Some(req), None) => quote! {
+            fn #name (&self, req: #req) -> impl Future<Output = Result<(), ZError>> + Sync;
+        },
+        (None, Some(resp)) => quote! {
+            fn #name (&self) -> impl Future<Output = Result<#resp, ZError>> + Sync;
+        },
+        _ => unreachable!(),
+    }
+}
+
+fn generate_async_server(interface: &Interface) -> TokenStream {
+    let server_name = ident(&(String::from("Async") + &interface.name.clone() + "Server"));
+    let server_trait = ident(&(String::from("Async") + &interface.name.clone() + "ServerHandler"));
+    let server_trait_methods = interface.methods.iter().map(generate_async_server_method);
+    let server_match_cases = interface.methods.iter().map(generate_async_server_case);
+    quote! {
+        pub trait #server_trait {
+            #(#server_trait_methods)*
+        }
+
+        pub struct #server_name<T: #server_trait> {
+            endpoint_cap: Capability,
+            handler: T
+        }
+
+        impl<T: #server_trait> #server_name<T> {
+            pub fn new(handler: T) -> Result<Self, ZError> {
+                Ok(Self {
+                    endpoint_cap: syscall::endpoint_create()?,
+                    handler,
+                })
+            }
+        }
+
+        impl<T: #server_trait + Send + Sync + 'static> yunq::server::AsyncYunqServer for #server_name<T> {
+            fn endpoint_cap(&self) -> &Capability {
+                &self.endpoint_cap
+            }
+
+            async fn handle_request(
+                &self,
+                method_number: u64,
+                byte_buffer: &mut ByteBuffer<1024>,
+                cap_buffer: &mut Vec<z_cap_t>,
+                ) -> Result<usize, ZError> {
+                match method_number {
+                    #(#server_match_cases)*
+
+                    _ => Err(ZError::UNIMPLEMENTED)
+                }
+            }
+        }
+    }
+}
+
 fn generate_interface(interface: &Interface) -> TokenStream {
     let client = generate_client(interface);
     let server = generate_server(interface);
+    let async_server = generate_async_server(interface);
     quote! {
         #client
 
         #server
+
+        #async_server
     }
 }
 
@@ -428,6 +531,7 @@ pub fn generate_code(ast: &[Decl]) -> String {
 
     let interface_imports = if any_interfaces(ast) {
         quote! {
+            use core::future::Future;
             use mammoth::cap::Capability;
             use mammoth::syscall;
         }