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|
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(())
}
|
