1 files changed, 48 insertions, 2 deletions

diff --git a/rust/crates/bridge/src/bridge.rs b/rust/crates/bridge/src/bridge.rs
index 52dee731..99b00615 100644
--- a/rust/crates/bridge/src/bridge.rs
+++ b/rust/crates/bridge/src/bridge.rs
@@ -1,10 +1,36 @@
 use proc_macro::TokenStream;
 use quote::quote;
-use syn::{ItemFn, parse_macro_input};
+use syn::{FnArg, Item, ItemConst, ItemFn, parse_macro_input};
 
 #[proc_macro_attribute]
 pub fn export(_attr: TokenStream, item: TokenStream) -> TokenStream {
-    let function = parse_macro_input!(item as ItemFn);
+    match parse_macro_input!(item as Item) {
+        Item::Fn(function) => export_fn(function),
+        Item::Const(constant) => export_const(constant),
+        other => syn::Error::new_spanned(other, "#[export] only supports fn and const items")
+            .to_compile_error()
+            .into(),
+    }
+}
+
+fn export_fn(function: ItemFn) -> TokenStream {
+    let param_count = function
+        .sig
+        .inputs
+        .iter()
+        .filter(|arg| matches!(arg, FnArg::Typed(_)))
+        .count();
+
+    if param_count > 1 {
+        return syn::Error::new_spanned(
+            &function.sig.inputs,
+            "#[export] functions must accept a single options struct, not positional arguments. \
+             Wrap parameters in a struct: `fn foo(FooOptions { a, b }: FooOptions)`",
+        )
+        .to_compile_error()
+        .into();
+    }
+
     let js_name = snake_to_camel(&function.sig.ident.to_string());
 
     quote! {
@@ -14,6 +40,26 @@ pub fn export(_attr: TokenStream, item: TokenStream) -> TokenStream {
     .into()
 }
 
+fn export_const(constant: ItemConst) -> TokenStream {
+    let js_name = constant.ident.to_string();
+    let const_ident = &constant.ident;
+    let getter_ident = syn::Ident::new(
+        &format!("__const_{}", constant.ident.to_string().to_lowercase()),
+        constant.ident.span(),
+    );
+
+    quote! {
+        #constant
+
+        #[cfg(feature = "wasm")]
+        #[::wasm_bindgen::prelude::wasm_bindgen(js_name = #js_name)]
+        pub fn #getter_ident() -> f64 {
+            #const_ident as f64
+        }
+    }
+    .into()
+}
+
 fn snake_to_camel(name: &str) -> String {
     let mut camel = String::with_capacity(name.len());
     let mut should_uppercase_next = false;