grpc_build_derive/
lib.rs

1//! proc macro to generate an associate function for all pb message types
2//! returning the full name of the message including the package namespace.
3
4use proc_macro::TokenStream;
5use syn::{spanned::Spanned, DeriveInput, Lit, MetaNameValue};
6
7#[proc_macro_derive(NamedMessage, attributes(name))]
8pub fn fully_qualified_name(input: TokenStream) -> TokenStream {
9    let ast = syn::parse_macro_input!(input as DeriveInput);
10
11    match impl_fully_qualified_name(&ast) {
12        Ok(tokens) => tokens,
13        Err(err) => err.to_compile_error().into(),
14    }
15}
16
17fn impl_fully_qualified_name(ast: &syn::DeriveInput) -> syn::Result<TokenStream> {
18    // We only annotate structs
19    match &ast.data {
20        syn::Data::Struct(_) => (),
21        syn::Data::Enum(_) => return Ok(Default::default()),
22        syn::Data::Union(_) => return Ok(Default::default()),
23    };
24
25    // search for #[name]
26    let mut name_attrs = ast.attrs.iter().filter(|attr| attr.path.is_ident("name"));
27
28    // Let's assume we only have one annotation
29    let meta = match name_attrs.next() {
30        Some(attr) => attr.parse_meta()?,
31        None => return Err(syn::Error::new(ast.span(), "missing #[name] attribute")),
32    };
33
34    // #[name = "pbname"] should map to a NameValue
35    //   path    Lit
36    let message_name = match meta {
37        syn::Meta::NameValue(MetaNameValue {
38            lit: Lit::Str(name),
39            ..
40        }) => name,
41        syn::Meta::NameValue(MetaNameValue { lit, .. }) => {
42            return Err(syn::Error::new(lit.span(), "message name MUST be a string"))
43        }
44        meta => return Err(syn::Error::new(meta.span(), "missing #[name] attribute")),
45    };
46
47    let name = &ast.ident;
48
49    Ok(quote::quote! {
50        impl ::grpc_build_core::NamedMessage for #name {
51            const NAME: &'static ::core::primitive::str = #message_name;
52        }
53    }
54    .into())
55}
grpc_build_derive/lib.rs

grpc_build_derive/
lib.rs
