xo-expression2: refactor: layout Variable support file locn

include/xo/expression2/variable/IExpression_DVariable.hpp

@@ -0,0 +1,66 @@
+/** @file IExpression_DVariable.hpp
+ *
+ *  Generated automagically from ingredients:
+ *  1. code generator:
+ *       [xo-facet/codegen/genfacet]
+ *     arguments:
+ *       --input [idl/IExpression_DVariable.json5]
+ *  2. jinja2 template for abstract facet .hpp file:
+ *       [iface_facet_repr.hpp.j2]
+ *  3. idl for facet methods
+ *       [idl/IExpression_DVariable.json5]
+ **/
+
+#pragma once
+
+#include "Expression.hpp"
+#include "Expression.hpp"
+#include "DVariable.hpp"
+
+namespace xo { namespace scm { class IExpression_DVariable; } }
+
+namespace xo {
+    namespace facet {
+        template <>
+        struct FacetImplementation<xo::scm::AExpression,
+                                   xo::scm::DVariable>
+        {
+            using ImplType = xo::scm::IExpression_Xfer
+              <xo::scm::DVariable,
+               xo::scm::IExpression_DVariable>;
+        };
+    }
+}
+
+namespace xo {
+    namespace scm {
+        /** @class IExpression_DVariable
+         **/
+        class IExpression_DVariable {
+        public:
+            /** @defgroup scm-expression-dvariable-type-traits **/
+            ///@{
+            using TypeDescr = xo::scm::AExpression::TypeDescr;
+            using Copaque = xo::scm::AExpression::Copaque;
+            using Opaque = xo::scm::AExpression::Opaque;
+            ///@}
+            /** @defgroup scm-expression-dvariable-methods **/
+            ///@{
+            // const methods
+            /** expression type (constant | apply | ..) **/
+            static exprtype extype(const DVariable & self) noexcept;
+            /** placeholder for type giving possible values for this expression **/
+            static TypeRef typeref(const DVariable & self) noexcept;
+            /** type giving possible values for this expression. Maybe null before typecheck **/
+            static TypeDescr valuetype(const DVariable & self) noexcept;
+
+            // non-const methods
+            /** assing to valuetype member. Useful when scaffolding expressions **/
+            static void assign_valuetype(DVariable & self, TypeDescr td) noexcept;
+            ///@}
+        };
+
+    } /*namespace scm*/
+} /*namespace xo*/
+
+/* end */