xo-expression: refactor: Lambda/Primitive share FunctionInterface

include/xo/expression/FunctionInterface.hpp

@@ -0,0 +1,34 @@
+/** @file FunctionInterface.hpp
+ *
+ *  Author: Roland Conybeare
+ **/
+
+#pragma once
+
+#include "Expression.hpp"
+//#include <cstdint>
+
+namespace xo {
+    namespace ast {
+        class FunctionInterface : public Expression {
+        public:
+            FunctionInterface(exprtype extype, TypeDescr fn_type)
+                : Expression(extype, fn_type) {}
+
+            /** downcast from Expression **/
+            static ref::brw<FunctionInterface> from(ref::brw<Expression> x) {
+                return ref::brw<FunctionInterface>::from(x);
+            }
+
+            virtual const std::string & name() const = 0;
+            virtual int n_arg() const = 0; // { return this->value_td()->n_fn_arg(); }
+            virtual TypeDescr fn_retval() const = 0; // { return this->value_td()->fn_retval(); }
+            virtual TypeDescr fn_arg(uint32_t i) const = 0; // { return this->value_td()->fn_arg(i); }
+
+        private:
+        }; /*FunctionInterface*/
+    } /*namespace ast*/
+} /*namespace xo*/
+
+
+/** end FunctionInterface.hpp **/