xactor_derive/
lib.rs

1extern crate proc_macro;
2
3use proc_macro::TokenStream;
4use proc_macro2::{Ident, Span};
5use quote::{quote, quote_spanned};
6use syn::spanned::Spanned;
7use syn::{parse_macro_input, AttributeArgs, DeriveInput, Error, Meta, NestedMeta};
8
9/// Implement an xactor message type.
10///
11/// The return value type defaults to (), and you can specify the type with the result parameter.
12///
13/// # Examples
14///
15/// ```ignore
16/// #[message(result = "i32")]
17/// struct TestMessage(i32);
18/// ```
19#[proc_macro_attribute]
20pub fn message(args: TokenStream, input: TokenStream) -> TokenStream {
21    let args = parse_macro_input!(args as AttributeArgs);
22    let mut result_type = quote! { () };
23
24    for arg in args {
25        if let NestedMeta::Meta(Meta::NameValue(nv)) = arg {
26            if nv.path.is_ident("result") {
27                if let syn::Lit::Str(lit) = nv.lit {
28                    if let Ok(ty) = syn::parse_str::<syn::Type>(&lit.value()) {
29                        result_type = quote! { #ty };
30                    } else {
31                        return Error::new_spanned(&lit, "Expect type")
32                            .to_compile_error()
33                            .into();
34                    }
35                }
36            }
37        }
38    }
39
40    let input = parse_macro_input!(input as DeriveInput);
41    let ident = &input.ident;
42    let expanded = quote! {
43        #input
44        impl xactor::Message for #ident {
45            type Result = #result_type;
46        }
47    };
48    expanded.into()
49}
50
51/// Implement an xactor main function.
52///
53/// Wait for all actors to exit.
54#[proc_macro_attribute]
55pub fn main(_args: TokenStream, input: TokenStream) -> TokenStream {
56    let mut input = syn::parse_macro_input!(input as syn::ItemFn);
57
58    if &*input.sig.ident.to_string() != "main" {
59        return TokenStream::from(quote_spanned! { input.sig.ident.span() =>
60            compile_error!("only the main function can be tagged with #[xactor::main]"),
61        });
62    }
63
64    if input.sig.asyncness.is_none() {
65        return TokenStream::from(quote_spanned! { input.span() =>
66            compile_error!("the async keyword is missing from the function declaration"),
67        });
68    }
69
70    input.sig.ident = Ident::new("__main", Span::call_site());
71    let ret = &input.sig.output;
72
73    let expanded = quote! {
74        #input
75
76        fn main() #ret {
77            xactor::block_on(__main())
78        }
79    };
80
81    expanded.into()
82}
xactor_derive/lib.rs

xactor_derive/
lib.rs
