Generate code to "send" a question

src/lib.rs

@@ -32,6 +32,14 @@ pub fn derive_protocol(input: TokenStream) -> TokenStream {
         }
     };
     let name = &input.ident;
+
+    let error_enum_name = format_ident!("{}Error", name);
+    let answer_enum_name = format_ident!("{}Answer", name);
+    let question_enum_name = format_ident!("{}Question", name);
+    let query_enum_name = format_ident!("{}Query", name);
+    let server_trait_name = format_ident!("{}Server", name);
+    let client_struct_name = format_ident!("{}Client", name);
+
     let vis = &input.vis;
 
     let mut server_trait = Vec::new();
@@ -40,6 +48,7 @@ pub fn derive_protocol(input: TokenStream) -> TokenStream {
     let mut client_enum = Vec::new();
 
     let mut query_enum = Vec::new();
+    let mut query_from_question_enum = Vec::new();
 
     for variant in &enum_.variants {
         // Every variant must have 2 fields
@@ -57,6 +66,7 @@ pub fn derive_protocol(input: TokenStream) -> TokenStream {
         let mut variant_fields = variant.fields.iter();
         let question_field = variant_fields.next().unwrap();
         let question_args = field_to_args(question_field);
+        let question_tuple_args = field_to_tuple_args(question_field);
         let answer_type = variant_fields.next().unwrap().ty.clone();
 
         // The variants that either the server or the client will use
@@ -67,14 +77,19 @@ pub fn derive_protocol(input: TokenStream) -> TokenStream {
         client_enum.push(quote! {
             #var_name(#question_field)
         });
+        // There is a From implementation for the client enum to the query enum
+        query_from_question_enum.push(quote! {
+            #question_enum_name::#var_name(question) => #query_enum_name::#var_name(question, None),
+        });
         // The function that the server needs to implement
         server_trait.push(quote! {
             fn #var_name(&mut self, #question_args) -> #answer_type;
         });
         // The function that the client uses to communicate
         client_impl.push(quote! {
-            pub fn #var_name(&mut self, #question_args) -> #answer_type {
-                ::std::unimplemented!()
+            pub async fn #var_name(&mut self, #question_args) -> Result<#answer_type, #error_enum_name> {
+                let nonce = self.send(#question_enum_name::#var_name(#question_tuple_args)).await?;
+                todo!("Wait for the answer")
             }
         });
         // The query enum is the same as the source enum, but the second field is always wrapped in a Option<>
@@ -83,58 +98,80 @@ pub fn derive_protocol(input: TokenStream) -> TokenStream {
         });
     }
 
+    // Create an error and result type for sending messages
+    let error_enum = quote! {
+        #vis enum #error_enum_name {
+            SendError(tokio::sync::mpsc::error::SendError<#question_enum_name>),
+        }
+    };
     // Create enums for the types of messages the server and client will use
-    let server_enum_name = format_ident!("{}Answer", name);
-    let server_enum = quote! {
-        #vis enum #server_enum_name {
+
+    let answer_enum = quote! {
+        #[derive(serde::Serialize, serde::Deserialize, Clone, Debug)]
+        #vis enum #answer_enum_name {
             #(#server_enum), *
         }
     };
-    let client_enum_name = format_ident!("{}Question", name);
-    let client_enum = quote! {
-        #[derive(serde::Serialize, serde::Deserialize)]
-        #vis enum #client_enum_name {
+    let question_enum = quote! {
+        #[derive(serde::Serialize, serde::Deserialize, Clone, Debug)]
+        #vis enum #question_enum_name {
             #(#client_enum), *
         }
     };
     // Create an enum to represent the queries the client has sent
-    let query_enum_name = format_ident!("{}Query", name);
     let query_enum = quote! {
-        #[derive(serde::Serialize, serde::Deserialize)]
+        #[derive(Clone, Debug)]
         #vis enum #query_enum_name {
             #(#query_enum), *
         }
+        impl From<#question_enum_name> for #query_enum_name {
+            fn from(query: #question_enum_name) -> Self {
+                match query {
+                    #(#query_from_question_enum)*
+                }
+            }
+        }
     };
     // Create a trait which the server will have to implement
-    let server_trait_name = format_ident!("{}Server", name);
     let server_trait = quote! {
         #vis trait #server_trait_name {
             #(#server_trait)*
         }
     };
     // Create a struct which the client will use to communicate
-    let client_struct_name = format_ident!("{}Client", name);
     let client_struct = quote! {
         #vis struct #client_struct_name {
             queries: ::std::collections::HashMap<u64, #query_enum_name>,
-            send_queue: tokio::sync::mpsc::Sender<#client_enum_name>,
-            recv_queue: tokio::sync::mpsc::Receiver<#server_enum_name>,
+            send_queue: tokio::sync::mpsc::Sender<#question_enum_name>,
+            recv_queue: tokio::sync::mpsc::Receiver<#answer_enum_name>,
         } // TODO: This struct will have some fields to handle the actual connection
         impl #client_struct_name {
-            pub fn new(send_queue: tokio::sync::mpsc::Sender<#client_enum_name>, recv_queue: tokio::sync::mpsc::Receiver<#server_enum_name>) -> Self {
+            pub fn new(send_queue: tokio::sync::mpsc::Sender<#question_enum_name>, recv_queue: tokio::sync::mpsc::Receiver<#answer_enum_name>) -> Self {
                 Self {
                     queries: ::std::collections::HashMap::new(),
                     send_queue,
                     recv_queue,
                 }
             }
+            async fn send(&mut self, query: #question_enum_name) -> Result<u64, #error_enum_name> {
+                let res = self.send_queue.send(query.clone()).await;
+                match res {
+                    Ok(_) => {
+                        let id = self.queries.len() as u64;
+                        self.queries.insert(id, query.into());
+                        Ok(id)
+                    }
+                    Err(e) => Err(#error_enum_name::SendError(e)),
+                }
+            }
             #(#client_impl)*
         }
     };
 
     let expanded = quote! {
-        #server_enum
-        #client_enum
+        #error_enum
+        #answer_enum
+        #question_enum
         #query_enum
         #server_trait
         #client_struct
@@ -171,3 +208,17 @@ fn field_to_args(field: &Field) -> proc_macro2::TokenStream {
         quote! { arg: #type_ }
     }
 }
+
+fn field_to_tuple_args(field: &Field) -> proc_macro2::TokenStream {
+    let type_ = &field.ty;
+    if let syn::Type::Tuple(tuple) = type_ {
+        let mut args = Vec::new();
+        for (i, elem) in tuple.elems.iter().enumerate() {
+            let arg = Ident::new(&format!("arg{}", i), elem.span());
+            args.push(quote! { #arg });
+        }
+        quote! { ( #( #args ), * ) }
+    } else {
+        quote! { (arg) }
+    }
+}

tests/mod.rs

@@ -29,8 +29,8 @@ impl TestProtocolServer for DummyServer {
         question.len() as i32
     }
 
-    fn addition(&mut self, arg0: i32, arg1: i32) -> i32 {
-        todo!()
+    fn addition(&mut self, a: i32, b: i32) -> i32 {
+        a + b
     }
 }