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use proc_macro2::{Span, TokenStream as TokenStream2};
use quote::{quote, quote_spanned};
use std::collections::HashSet;
impl RpcDescription {
pub(super) fn render_server(&self) -> Result<TokenStream2, syn::Error> {
let trait_name = quote::format_ident!("{}Server", &self.trait_def.ident);
let method_impls = self.render_methods()?;
let into_rpc_impl = self.render_into_rpc()?;
let async_trait = self.jrps_server_item(quote! { types::__reexports::async_trait });
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// Doc-comment to be associated with the server.
let doc_comment = format!("Server trait implementation for the `{}` RPC API.", &self.trait_def.ident);
let trait_impl = quote! {
#[#async_trait]
#[doc = #doc_comment]
pub trait #trait_name: Sized + Send + Sync + 'static {
#method_impls
#into_rpc_impl
}
};
Ok(trait_impl)
}
fn render_methods(&self) -> Result<TokenStream2, syn::Error> {
let methods = self.methods.iter().map(|method| &method.signature);
let subscription_sink_ty = self.jrps_server_item(quote! { SubscriptionSink });
let subscriptions = self.subscriptions.iter().cloned().map(|mut sub| {
// Add `SubscriptionSink` as the second input parameter to the signature.
let subscription_sink: syn::FnArg = syn::parse_quote!(subscription_sink: #subscription_sink_ty);
sub.signature.sig.inputs.insert(1, subscription_sink);
sub.signature
});
Ok(quote! {
#(#methods)*
#(#subscriptions)*
})
}
fn render_into_rpc(&self) -> Result<TokenStream2, syn::Error> {
let jrps_error = self.jrps_server_item(quote! { types::Error });
let rpc_module = self.jrps_server_item(quote! { RpcModule });
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let mut registered = HashSet::new();
let mut errors = Vec::new();
let mut check_name = |name: String, span: Span| {
if registered.contains(&name) {
let message = format!("{:?} is already defined", name);
errors.push(quote_spanned!(span => compile_error!(#message);));
} else {
registered.insert(name);
}
};
let methods = self
.methods
.iter()
.map(|method| {
// Rust method to invoke (e.g. `self.<foo>(...)`).
let rust_method_name = &method.signature.sig.ident;
// Name of the RPC method (e.g. `foo_makeSpam`).
let rpc_method_name = self.rpc_identifier(&method.name);
// `parsing` is the code associated with parsing structure from the
// provided `RpcParams` object.
// `params_seq` is the comma-delimited sequence of parametsrs.
let is_method = true;
let (parsing, params_seq) = self.render_params_decoding(&method.params, is_method);
check_name(rpc_method_name.clone(), rust_method_name.span());
if method.signature.sig.asyncness.is_some() {
quote! {
rpc.register_async_method(#rpc_method_name, |params, context| {
let fut = async move {
#parsing
Ok(context.as_ref().#rust_method_name(#params_seq).await)
};
Box::pin(fut)
})?;
}
} else {
quote! {
rpc.register_method(#rpc_method_name, |params, context| {
Ok(context.#rust_method_name(#params_seq))
})?;
}
})
.collect::<Vec<_>>();
let subscriptions = self
.subscriptions
.iter()
.map(|sub| {
// Rust method to invoke (e.g. `self.<foo>(...)`).
let rust_method_name = &sub.signature.sig.ident;
// Name of the RPC method to subscribe to (e.g. `foo_sub`).
let rpc_sub_name = self.rpc_identifier(&sub.name);
// Name of the RPC method to unsubscribe (e.g. `foo_sub`).
let rpc_unsub_name = self.rpc_identifier(&sub.unsub_method);
// `parsing` is the code associated with parsing structure from the
// provided `RpcParams` object.
// `params_seq` is the comma-delimited sequence of parametsrs.
let is_method = false;
let (parsing, params_seq) = self.render_params_decoding(&sub.params, is_method);
check_name(rpc_sub_name.clone(), rust_method_name.span());
check_name(rpc_unsub_name.clone(), rust_method_name.span());
rpc.register_subscription(#rpc_sub_name, #rpc_unsub_name, |params, sink, context| {
Ok(context.as_ref().#rust_method_name(sink, #params_seq))
let doc_comment = "Collects all the methods and subscriptions defined in the trait \
and adds them into a single `RpcModule`.";
Ok(quote! {
#[doc = #doc_comment]
fn into_rpc(self) -> #rpc_module<Self> {
let inner = move || -> Result<#rpc_module<Self>, #jrps_error> {
let mut rpc = #rpc_module::new(self);
#(#errors)*
#(#methods)*
#(#subscriptions)*
inner().expect("RPC macro method names should never conflict")
}
})
}
fn render_params_decoding(
&self,
params: &[(syn::PatIdent, syn::Type)],
is_method: bool,
) -> (TokenStream2, TokenStream2) {
if params.is_empty() {
return (TokenStream2::default(), TokenStream2::default());
}
// Implementations for `.map_err(...)?` and `.ok_or(...)?` with respect to the expected
// error return type.
let (err, map_err_impl, ok_or_impl) = if is_method {
// For methods, we return `CallError`.
let jrps_call_error = self.jrps_server_item(quote! { types::CallError });
let err = quote! { #jrps_call_error::InvalidParams };
let map_err = quote! { .map_err(|_| #jrps_call_error::InvalidParams)? };
let ok_or = quote! { .ok_or(#jrps_call_error::InvalidParams)? };
(err, map_err, ok_or)
} else {
// For subscriptions, we return `Error`.
// Note that while `Error` can be constructed from `CallError`, we should not do it,
// because it would be an abuse of the error type semantics.
// Instead, we use suitable top-level error variants.
let jrps_error = self.jrps_server_item(quote! { types::Error });
let err = quote! { #jrps_error::Request("Required paramater missing".into()) };
let map_err = quote! { .map_err(|err| #jrps_error::ParseError(err))? };
let ok_or = quote! { .ok_or(#jrps_error::Request("Required paramater missing".into()))? };
(err, map_err, ok_or)
};
let serde_json = self.jrps_server_item(quote! { types::__reexports::serde_json });
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// Parameters encoded as a tuple (to be parsed from array).
let (params_fields_seq, params_types_seq): (Vec<_>, Vec<_>) = params.iter().cloned().unzip();
let params_types = quote! { (#(#params_types_seq),*) };
let params_fields = quote! { (#(#params_fields_seq),*) };
// Code to decode sequence of parameters from a JSON array.
let decode_array = {
let decode_fields = params.iter().enumerate().map(|(id, (name, ty))| {
if is_option(ty) {
quote! {
let #name = arr
.get(#id)
.cloned()
.map(#serde_json::from_value)
.transpose()
#map_err_impl;
}
} else {
quote! {
let #name = arr
.get(#id)
.cloned()
.map(#serde_json::from_value)
#ok_or_impl
#map_err_impl;
}
}
});
quote! {
#(#decode_fields);*
#params_fields
}
};
// Code to decode sequence of parameters from a JSON object (aka map).
let decode_map = {
let decode_fields = params.iter().map(|(name, ty)| {
let name_str = name.ident.to_string();
if is_option(ty) {
quote! {
let #name = obj
.get(#name_str)
.cloned()
.map(#serde_json::from_value)
.transpose()
#map_err_impl;
}
} else {
quote! {
let #name = obj
.get(#name_str)
.cloned()
.map(#serde_json::from_value)
#ok_or_impl
#map_err_impl;
}
}
});
quote! {
#(#decode_fields);*
#params_fields
}
};
// Code to decode single parameter from a JSON primitive.
let decode_single = if params.len() == 1 {
quote! {
#serde_json::from_value(json)
#map_err_impl
}
} else {
quote! { return Err(#err);}
};
// Parsing of `serde_json::Value`.
let parsing = quote! {
let json: #serde_json::Value = params.parse()?;
let #params_fields: #params_types = match json {
#serde_json::Value::Null => return Err(#err),
#serde_json::Value::Array(arr) => {
#decode_array
}
#serde_json::Value::Object(obj) => {
#decode_map
}
_ => {
#decode_single
}
};
};
let seq = quote! {
#(#params_fields_seq),*
};
(parsing, seq)
}
}
/// Checks whether provided type is an `Option<...>`.
fn is_option(ty: &syn::Type) -> bool {
if let syn::Type::Path(path) = ty {
// TODO: Probably not the best way to check whether type is an `Option`.
if path.path.segments.iter().any(|seg| seg.ident == "Option") {
return true;
}
}
false
}