1 files changed, 174 insertions, 0 deletions
diff --git a/jsonrpc/impl/src/lib.rs b/jsonrpc/impl/src/lib.rs
new file mode 100644
index 0000000..8814e61
--- /dev/null
+++ b/jsonrpc/impl/src/lib.rs
@@ -0,0 +1,174 @@
+use proc_macro::TokenStream;
+use proc_macro2::TokenStream as TokenStream2;
+use quote::quote;
+use syn::{
+    parse_macro_input, spanned::Spanned, FnArg, ImplItem, ItemImpl, ReturnType, Signature, Type,
+    TypePath,
+};
+
+macro_rules! err {
+    ($($tt:tt)*) => {
+        return syn::Error::new($($tt)*).to_compile_error().into()
+    };
+}
+
+#[proc_macro_attribute]
+pub fn rpc_impl(_attr: TokenStream, item: TokenStream) -> TokenStream {
+    let item2 = item.clone();
+    let parsed_input = parse_macro_input!(item2 as ItemImpl);
+
+    let self_ty = match *parsed_input.self_ty {
+        Type::Path(p) => p,
+        _ => err!(
+            parsed_input.span(),
+            "Implementing the trait `RPCService` on this type is unsupported"
+        ),
+    };
+
+    let methods = match parse_struct_methods(&self_ty, parsed_input.items) {
+        Ok(res) => res,
+        Err(err) => return err.to_compile_error().into(),
+    };
+
+    let mut method_idents = vec![];
+    for method in methods.iter() {
+        method_idents.push(method.ident.clone());
+        if method.inputs.len() != 2 {
+            err!(
+                method.span(),
+                "requires `&self` and a parameter of type `serde_json::Value`"
+            );
+        }
+
+        if let Err(err) = validate_method(method) {
+            return err.to_compile_error().into();
+        }
+    }
+
+    let impl_methods: Vec<TokenStream2> = method_idents.iter().map(
+        |m| quote! {
+            stringify!(#m) => Some(Box::new(move |params: serde_json::Value| Box::pin(self.#m(params)))),
+        },
+    ).collect();
+
+    let item: TokenStream2 = item.into();
+    quote! {
+        impl karyon_jsonrpc::RPCService for #self_ty {
+            fn get_method<'a>(
+                &'a self,
+                name: &'a str
+            ) -> Option<karyon_jsonrpc::RPCMethod> {
+                match name {
+                #(#impl_methods)*
+                    _ => None,
+                }
+            }
+            fn name(&self) -> String{
+                stringify!(#self_ty).to_string()
+            }
+        }
+        #item
+    }
+    .into()
+}
+
+#[proc_macro_attribute]
+pub fn rpc_pubsub_impl(_attr: TokenStream, item: TokenStream) -> TokenStream {
+    let item2 = item.clone();
+    let parsed_input = parse_macro_input!(item2 as ItemImpl);
+
+    let self_ty = match *parsed_input.self_ty {
+        Type::Path(p) => p,
+        _ => err!(
+            parsed_input.span(),
+            "Implementing the trait `PubSubRPCService` on this type is unsupported"
+        ),
+    };
+
+    let methods = match parse_struct_methods(&self_ty, parsed_input.items) {
+        Ok(res) => res,
+        Err(err) => return err.to_compile_error().into(),
+    };
+
+    let mut method_idents = vec![];
+    for method in methods.iter() {
+        method_idents.push(method.ident.clone());
+        if method.inputs.len() != 4 {
+            err!(method.span(), "requires `&self` and three parameters: `Arc<Channel>`, method: `String`, and `serde_json::Value`");
+        }
+        if let Err(err) = validate_method(method) {
+            return err.to_compile_error().into();
+        }
+    }
+
+    let impl_methods: Vec<TokenStream2> = method_idents.iter().map(
+        |m| quote! {
+            stringify!(#m) => {
+                Some(Box::new(
+                    move |chan: std::sync::Arc<karyon_jsonrpc::Channel>, method: String, params: serde_json::Value| {
+                    Box::pin(self.#m(chan, method, params))
+                }))
+            },
+        },
+    ).collect();
+
+    let item: TokenStream2 = item.into();
+    quote! {
+        impl karyon_jsonrpc::PubSubRPCService for #self_ty {
+            fn get_pubsub_method<'a>(
+                &'a self,
+                name: &'a str
+            ) -> Option<karyon_jsonrpc::PubSubRPCMethod> {
+                match name {
+                #(#impl_methods)*
+                    _ => None,
+                }
+            }
+
+            fn name(&self) -> String{
+                stringify!(#self_ty).to_string()
+            }
+        }
+        #item
+    }
+    .into()
+}
+
+fn parse_struct_methods(
+    self_ty: &TypePath,
+    items: Vec<ImplItem>,
+) -> Result<Vec<Signature>, syn::Error> {
+    let mut methods: Vec<Signature> = vec![];
+
+    if items.is_empty() {
+        return Err(syn::Error::new(
+            self_ty.span(),
+            "At least one method should be implemented",
+        ));
+    }
+
+    for item in items {
+        match item {
+            ImplItem::Fn(method) => {
+                methods.push(method.sig);
+            }
+            _ => return Err(syn::Error::new(item.span(), "Unexpected item!")),
+        }
+    }
+
+    Ok(methods)
+}
+
+fn validate_method(method: &Signature) -> Result<(), syn::Error> {
+    if let FnArg::Typed(_) = method.inputs[0] {
+        return Err(syn::Error::new(method.span(), "requires `&self` parameter"));
+    }
+
+    if let ReturnType::Default = method.output {
+        return Err(syn::Error::new(
+            method.span(),
+            "requires `Result<serde_json::Value, RPCError>` as return type",
+        ));
+    }
+    Ok(())
+}