xo-interpreter2 stack: scaffold DClosure, DLocalEnv [WIP]

include/xo/interpreter2/DLocalEnv.hpp

@@ -0,0 +1,67 @@
+/** @file DLocalEnv.hpp
+ *
+ *  @author Roland Conybeare, Feb 2026
+ **/
+
+#pragma once
+
+#include <xo/expression2/LocalSymtab.hpp>
+#include <xo/object2/DArray.hpp>
+
+namespace xo {
+    namespace scm {
+
+        /** @brief bindings for arguments to a lambda
+         **/
+        class DLocalEnv {
+        public:
+            using DArray = xo::scm::DArray;
+            using AAllocator = xo::mm::AAllocator;
+            using AGCObject = xo::mm::AGCObject;
+            using ppindentinfo = xo::print::ppindentinfo;
+            using size_type = std::uint32_t;
+
+        public:
+            /** @defgroup scm-localenv-constructors constructors **/
+            ///@{
+
+            /** empty instance with parent @p p for variables in @p symtab **/
+            DLocalEnv(DLocalEnv * parent,
+                      DLocalSymtab * symtab,
+                      DArray * args);
+
+            static DLocalEnv * _make_empty(obj<AAllocator> mm,
+                                           DLocalEnv * parent,
+                                           DLocalSymtab * symtab,
+                                           DArray * args);
+
+            ///@}
+            /** @defgroup scm-local-env-methods methods **/
+            ///@{
+
+            DLocalEnv * parent() const noexcept { return parent_; }
+            size_type size() const noexcept { return symtab_->size(); }
+
+            /** lookup current value associated with binding @p ix **/
+            obj<AGCObject> lookup_value(Binding ix) const noexcept;
+
+            /** assign value associated with binding @p ix to @p x **/
+            void assign_value(Binding ix, obj<AGCObject> x);
+
+            ///@}
+
+        private:
+            /** parent environment (from closure) **/
+            DLocalEnv * parent_ = nullptr;
+            /** bind values for variables in this symbol table **/
+            DLocalSymtab * symtab_ = nullptr;
+            /** bindings.
+             *  (*args)[i] associates a value with symtab->slots_[i]
+             **/
+            DArray * args_ = nullptr;;
+        };
+
+    } /*namespace scm*/
+} /*namespace xo*/
+
+/* end DLocalEnv.hpp */