Api traits test code (#487)

Add initial templated API test support. This needs to be improved to use an attribute macro, but that will require some major surgery :(

cuda_macros/src/lib.rs

@@ -10,7 +10,7 @@ use syn::punctuated::Punctuated;
 use syn::visit_mut::VisitMut;
 use syn::{
     bracketed, parse_macro_input, File, ForeignItem, ForeignItemFn, Ident, Item, Path, Signature,
-    Token,
+    Token, token
 };
 
 const CUDA_RS: &'static str = include_str! {"cuda.rs"};
@@ -308,3 +308,40 @@ fn join(
     }
     
 }
+
+#[proc_macro]
+pub fn generate_api_macro(input: TokenStream) -> TokenStream {
+    let input = parse_macro_input!(input as ApiMacroInput);
+    let ApiMacroInput(_, trait_name, _, type_name, _, macro_name) = input;
+    let expanded = quote! {
+        struct #type_name;
+        macro_rules! #macro_name {
+            ($($abi:literal fn $fn_name:ident( $( $arg_id:ident : $arg_type:ty ),* ) -> $ret_type:ty;)*) => {
+                impl #trait_name for #type_name {
+                    fn new() -> Self { Self }
+                    $(
+                        #[inline(always)]
+                        fn $fn_name(&self, $( $arg_id : $arg_type ),* ) -> $ret_type {
+                            unsafe { super::$fn_name( $( $arg_id ),* ) }
+                        }
+                    )*
+                }
+            };
+        }
+    };
+    TokenStream::from(expanded)
+}
+#[allow(dead_code)]
+struct ApiMacroInput(token::Impl, Path, token::For, Path, token::Use, Ident);
+impl syn::parse::Parse for ApiMacroInput {
+    fn parse(input: syn::parse::ParseStream) -> syn::Result<Self> {
+        Ok(ApiMacroInput(
+            input.parse()?, // impl 
+            input.parse()?, // trait
+            input.parse()?, // for
+            input.parse()?, // type
+            input.parse()?, // using
+            input.parse()?  // macro
+        ))
+    }
+}