Add a default typed template parameter to functions

1 files changed, 21 insertions, 4 deletions

diff --git a/modules/codec/c++/interface.hpp b/modules/codec/c++/interface.hpp
index 19dc145..f77c05f 100644
--- a/modules/codec/c++/interface.hpp
+++ b/modules/codec/c++/interface.hpp
@@ -3,25 +3,42 @@
 #include <functional>
 
 #include <forstio/error.hpp>
+
 #include "schema.hpp"
 #include "data.hpp"
 
 namespace saw {
-template<typename SchemaFunc, typename Encode>
+template<typename SchemaFunc, typename Encode, typename Context = void_t >
 class function;
 
+namespace impl {
+template<typename Request, typename Response, typename Encode, typename Ctx>
+struct FuncTypeHelper {
+	using Type = std::function<data<Response, Encode>(data<Request, Encode>, Ctx)>;
+};
+
 template<typename Request, typename Response, typename Encode>
-class function<schema::Function<Request, Response>, Encode> {
+struct FuncTypeHelper<Request, Response, Encode, void_t> {
+	using Type = std::function<data<Response, Encode>(data<Request, Encode>)>;
+};
+}
+
+template<typename Request, typename Response, typename Encode, typename Context>
+class function<schema::Function<Request, Response>, Encode, Context> {
 private:
-	std::function<data<Response, Encode>(data<Request, Encode>)> func_;
+	typename impl::FuncTypeHelper<Request, Response, Encode, Context>::Type func_;
 public:
 	template<typename Func>
 		function(Func func):
 				func_{std::move(func)}
 		{}
 
-		error_or<data<Response, Encode>> call(data<Request, Encode> req){
+		error_or<data<Response, Encode>> call(data<Request, Encode> req, Context ctx = {}){
+			if constexpr (std::is_same_v<Context, void_t>){
 				return func_(std::move(req));
+			} else {
+				return func_(std::move(req), ctx);
+			}
 		}
 };