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use proc_macro::TokenStream;
use quote::quote;
use serde::Deserialize;
static NAPI_EXPORTS: &str = include_str!("./symbol_exports.json");
#[derive(Deserialize)]
struct SymbolExports {
pub symbols: Vec<String>,
}
#[proc_macro_attribute]
pub fn napi_sym(_attr: TokenStream, item: TokenStream) -> TokenStream {
let func = syn::parse::<syn::ItemFn>(item).expect("expected a function");
let exports: SymbolExports =
serde_json::from_str(NAPI_EXPORTS).expect("failed to parse exports");
let name = &func.sig.ident;
assert!(
exports.symbols.contains(&name.to_string()),
"tools/napi/sym/symbol_exports.json is out of sync!"
);
let block = &func.block;
let inputs = &func.sig.inputs;
let output = &func.sig.output;
let generics = &func.sig.generics;
let ret_ty = match output {
syn::ReturnType::Default => panic!("expected a return type"),
syn::ReturnType::Type(_, ty) => quote! { #ty },
};
TokenStream::from(quote! {
#[no_mangle]
pub unsafe extern "C" fn #name #generics (#inputs) -> napi_status {
let mut inner = || -> #ret_ty {
#block
};
inner()
.map(|_| napi_ok)
.unwrap_or_else(|e| e.into())
}
})
}