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extern crate proc_macro;
use proc_macro::TokenStream;
use quote::quote;
use syn::{Data, DeriveInput, Fields, parse_macro_input};
#[proc_macro_derive(ActorMessage)]
pub fn actor_message(input: TokenStream) -> TokenStream {
let input = parse_macro_input!(input as DeriveInput);
let message_name = &input.ident;
let message_vis = &input.vis;
let caller_name = syn::Ident::new(&format!("{}Caller", message_name), message_name.span());
let weak_caller_name = syn::Ident::new(&format!("{}WeakCaller", message_name), message_name.span());
let replyer_name = syn::Ident::new(&format!("{}Replyer", message_name), message_name.span());
let mut caller_methods = Vec::new();
match &input.data {
Data::Enum(data) => {
for variant in &data.variants {
let variant_name = &variant.ident;
let snake_case_name = to_snake_case(&variant_name.to_string());
let method_name = syn::Ident::new(&snake_case_name, variant_name.span());
let timeout_method_name = syn::Ident::new(&format!("{}_timeout", snake_case_name), variant_name.span());
let method_name_str = snake_case_name.clone();
match &variant.fields {
// single unnamed field: either an ActorPacket (request/response) or a plain payload (fire-and-forget)
Fields::Unnamed(fields) if fields.unnamed.len() == 1 => {
let arg_ty = &fields.unnamed[0].ty;
// detect ActorPacket<T, R>
let mut is_actor_packet = false;
if let syn::Type::Path(tp) = arg_ty {
if let Some(segment) = tp.path.segments.last() {
if segment.ident == "ActorPacket" {
is_actor_packet = true;
}
}
}
if is_actor_packet {
if let syn::Type::Path(tp) = arg_ty {
if let Some(segment) = tp.path.segments.last() {
if segment.ident == "ActorPacket" {
if let syn::PathArguments::AngleBracketed(args) = &segment.arguments {
if args.args.len() == 2 {
let args_type = &args.args[0];
let ret_type = &args.args[1];
caller_methods.push(quote! {
pub async fn #method_name(&self, args: #args_type) -> anyhow::Result<#ret_type> {
let (packet, rx) = ActorPacket::new(args);
self.0.send(#message_name::#variant_name(packet))
.map_err(|e| {
let context = format!("Fail to `{}`, error: {}", #method_name_str, e);
anyhow::anyhow!(e).context(context)
})?;
rx.wait().await
.map_err(|e| {
let context = format!("Fail to `{}`, error: {}", #method_name_str, e);
anyhow::anyhow!(e).context(context)
})
}
});
caller_methods.push(quote! {
pub async fn #timeout_method_name(&self, args: #args_type, duration: ::std::time::Duration) -> anyhow::Result<#ret_type> {
let (packet, rx) = ActorPacket::new(args);
self.0.send(#message_name::#variant_name(packet))
.map_err(|e| {
let context = format!("Fail to `{}`, error: {}", #method_name_str, e);
anyhow::anyhow!(e).context(context)
})?;
rx.wait_timeout(duration).await
.map_err(|e| {
let context = format!("Fail to `{}`, error: {}", #method_name_str, e);
anyhow::anyhow!(e).context(context)
})
}
});
}
}
}
}
}
} else {
// fire-and-forget: generate a synchronous method that sends the variant without awaiting
let args_type = arg_ty;
caller_methods.push(quote! {
pub fn #method_name(&self, args: #args_type) {
let _ = self.0.send(#message_name::#variant_name(args));
}
});
}
},
Fields::Named(_fields) => {
// currently ignore named-field variants
},
_ => {},
}
}
},
Data::Struct(data) => {
let fields = match &data.fields {
Fields::Unnamed(fields) if fields.unnamed.len() == 1 => fields,
_ => {
return syn::Error::new_spanned(&input, "ActorMessage tuple struct must have exactly one field")
.to_compile_error()
.into();
},
};
let arg_ty = &fields.unnamed[0].ty;
let snake_case_name = to_snake_case(&message_name.to_string());
let method_name = syn::Ident::new(&snake_case_name, message_name.span());
let timeout_method_name = syn::Ident::new(&format!("{}_timeout", snake_case_name), message_name.span());
let method_name_str = snake_case_name.clone();
// detect ActorPacket<T, R>
let mut is_actor_packet = false;
if let syn::Type::Path(tp) = arg_ty {
if let Some(segment) = tp.path.segments.last() {
if segment.ident == "ActorPacket" {
is_actor_packet = true;
}
}
}
if is_actor_packet {
if let syn::Type::Path(tp) = arg_ty {
if let Some(segment) = tp.path.segments.last() {
if segment.ident == "ActorPacket" {
if let syn::PathArguments::AngleBracketed(args) = &segment.arguments {
if args.args.len() == 2 {
let args_type = &args.args[0];
let ret_type = &args.args[1];
caller_methods.push(quote! {
pub async fn #method_name(&self, args: #args_type) -> anyhow::Result<#ret_type> {
let (packet, rx) = ActorPacket::new(args);
self.0.send(#message_name(packet))
.map_err(|e| {
let context = format!("Fail to `{}`, error: {}", #method_name_str, e);
anyhow::anyhow!(e).context(context)
})?;
rx.wait().await
.map_err(|e| {
let context = format!("Fail to `{}`, error: {}", #method_name_str, e);
anyhow::anyhow!(e).context(context)
})
}
});
caller_methods.push(quote! {
pub async fn #timeout_method_name(&self, args: #args_type, duration: ::std::time::Duration) -> anyhow::Result<#ret_type> {
let (packet, rx) = ActorPacket::new(args);
self.0.send(#message_name(packet))
.map_err(|e| {
let context = format!("Fail to `{}`, error: {}", #method_name_str, e);
anyhow::anyhow!(e).context(context)
})?;
rx.wait_timeout(duration).await
.map_err(|e| {
let context = format!("Fail to `{}`, error: {}", #method_name_str, e);
anyhow::anyhow!(e).context(context)
})
}
});
}
}
}
}
}
} else {
// fire-and-forget: generate a synchronous method that sends the struct without awaiting
let args_type = arg_ty;
caller_methods.push(quote! {
pub fn #method_name(&self, args: #args_type) {
let _ = self.0.send(#message_name(args));
}
});
}
},
_ => {
return syn::Error::new_spanned(&input, "ActorMessage can only be derived for enums or tuple structs")
.to_compile_error()
.into();
},
}
let expanded = quote! {
#[derive(Clone, Debug)]
#message_vis struct #caller_name(::tokio::sync::mpsc::UnboundedSender<#message_name>);
impl #caller_name {
pub fn downgrade(&self) -> #weak_caller_name {
#weak_caller_name(self.0.downgrade())
}
#(#caller_methods)*
}
impl ::std::convert::AsRef<::tokio::sync::mpsc::UnboundedSender<#message_name>> for #caller_name {
fn as_ref(&self) -> &::tokio::sync::mpsc::UnboundedSender<#message_name> {
&self.0
}
}
#[derive(Clone, Debug)]
#message_vis struct #weak_caller_name(::tokio::sync::mpsc::WeakUnboundedSender<#message_name>);
impl #weak_caller_name {
pub fn upgrade(&self) -> Option<#caller_name> {
self.0.upgrade().map(#caller_name)
}
}
#message_vis struct #replyer_name(::tokio::sync::mpsc::UnboundedReceiver<#message_name>);
impl #replyer_name {
pub async fn recv(&mut self) -> Option<#message_name> {
self.0.recv().await
}
}
impl std::ops::Deref for #replyer_name {
type Target = ::tokio::sync::mpsc::UnboundedReceiver<#message_name>;
fn deref(&self) -> &Self::Target {
&self.0
}
}
impl std::ops::DerefMut for #replyer_name {
fn deref_mut(&mut self) -> &mut Self::Target {
&mut self.0
}
}
impl #message_name {
pub fn actor() -> (#caller_name, #replyer_name) {
let (tx, rx) = ::tokio::sync::mpsc::unbounded_channel();
(#caller_name(tx), #replyer_name(rx))
}
}
};
TokenStream::from(expanded)
}
fn to_snake_case(s: &str) -> String {
let mut result = String::new();
for (i, c) in s.chars().enumerate() {
if i == 0 {
result.push(c.to_lowercase().next().unwrap());
} else if c.is_uppercase() {
result.push('_');
result.push(c.to_lowercase().next().unwrap());
} else {
result.push(c);
}
}
result
}