1 files changed, 52 insertions, 0 deletions
diff --git a/matrix-macros/src/lib.rs b/matrix-macros/src/lib.rs
new file mode 100644
index 0000000..8099fd6
--- /dev/null
+++ b/matrix-macros/src/lib.rs
@@ -0,0 +1,52 @@
+use proc_macro::TokenStream;
+use syn::{ItemFn, parse::Parse, Token, LitBool, LitInt};
+use quote::quote;
+
+struct NativeFuncParams {
+    arity: LitInt,
+    variadic: LitBool,
+}
+
+impl Parse for NativeFuncParams {
+    fn parse(input: syn::parse::ParseStream) -> syn::Result<Self> {
+        let arity = input.parse()?;
+        input.parse::<Token![,]>()?;
+        let variadic = input.parse()?;
+        Ok(Self { arity , variadic })
+    }
+}
+
+#[proc_macro_attribute]
+pub fn native_func(input: TokenStream, annotated_item: TokenStream) -> TokenStream {
+    let itemfn: ItemFn = syn::parse(annotated_item).unwrap();
+
+    let input: NativeFuncParams = syn::parse(input).unwrap();
+    let arity = input.arity;
+    let variadic = input.variadic;
+
+    let visibility = itemfn.vis;
+    let block = itemfn.block;
+    let name = itemfn.sig.ident;
+    let name_str = name.to_string();
+    let inputs = itemfn.sig.inputs;
+    let output = itemfn.sig.output;
+
+    assert!(itemfn.sig.constness.is_none(), "item must not be const");
+    assert!(itemfn.sig.asyncness.is_none(), "item must not be async");
+    assert!(itemfn.sig.unsafety.is_none(), "item must not be unsafe");
+    assert!(itemfn.sig.abi.is_none(), "item must not contain an ABI specifier");
+    assert!(itemfn.sig.variadic.is_none(), "item must not be variadic");
+
+    let expanded = quote! {
+        #visibility fn #name() -> ::std::rc::Rc< ::matrix::chunk::Function> {
+            ::std::rc::Rc::new( ::matrix::chunk::Function {
+                name: ::std::rc::Rc::from( #name_str ),
+                arity: #arity,
+                variadic: #variadic,
+                fun: ::matrix::chunk::InnerFunction::Native(Box::new(|#inputs| #output #block))
+            })
+        }
+    };
+
+    TokenStream::from(expanded)
+}