xo-interpreter2 stack: refactor + bugfix operator expr

include/xo/reader2/DGlobalEnv.hpp

@@ -0,0 +1,94 @@
+/** @file DGlobalEnv.hpp
+ *
+ *  @author Roland Conybeare, Feb 2026
+ **/
+
+#pragma once
+
+#include <xo/expression2/DGlobalSymtab.hpp>
+#include <xo/object2/DArray.hpp>
+
+namespace xo {
+    namespace scm {
+
+        /** @brief runtime bindings for global variabels
+         *
+         *  Implementation here uses a DArenaHashMap to hold <key,value> pairs.
+         *  The hash map has its own memory outside GC space.
+         *  Keys are DUniqueStrings, also outside GC space.
+         *  Values are regular gc-aware objects, generally will be in GC space.
+         *
+         *  We need collector to traverse all the values in a global env
+         *  on each cycle.  Arrange that by having DGlobalEnv itself
+         *  in GC space.
+         *
+         **/
+        class DGlobalEnv {
+        public:
+            using TypeDescr = xo::reflect::TypeDescr;
+            using ACollector = xo::mm::ACollector;
+            using AAllocator = xo::mm::AAllocator;
+            using AGCObject = xo::mm::AGCObject;
+            using MemorySizeVisitor = xo::mm::MemorySizeVisitor;
+            using ppindentinfo = xo::print::ppindentinfo;
+            using size_type = std::uint32_t;
+
+        public:
+            /** @defgroup scm-globalenv-ctors constructors **/
+            ///@{
+
+            DGlobalEnv(DGlobalSymtab * symtab, DArray * values);
+
+            static DGlobalEnv * _make(obj<AAllocator> mm,
+                                      DGlobalSymtab * symtab);
+
+
+            ///@}
+            /** @defgroup scm-globalenv-methods methods **/
+            ///@{
+
+            /** symbol-table size.  Is the number of distinct global variables **/
+            size_type n_vars() const noexcept { return symtab_->n_vars(); }
+
+            /** lookup current value associated with binding @p ix **/
+            obj<AGCObject> lookup_value(Binding ix) const noexcept;
+
+            /** assign value associated with binding @p to @p x.
+             *  If need to expand size of this env, use memory from @p mm
+             **/
+            void assign_value(obj<AAllocator> mm, Binding ix, obj<AGCObject> x);
+
+            /** create/establish global for symbol @p sym with resolved type @p td
+             *  and associate with @p value.
+             **/
+            DVariable * _upsert_value(obj<AAllocator> mm,
+                                      const DUniqueString * sym,
+                                      TypeDescr td,
+                                      obj<AGCObject> value);
+
+            ///@}
+            /** @defgroup scm-globalenv-gcobject-facet **/
+            ///@{
+
+            std::size_t shallow_size() const noexcept;
+            DGlobalEnv * shallow_copy(obj<AAllocator> mm) const noexcept;
+            std::size_t forward_children(obj<ACollector> gc) noexcept;
+
+            ///@}
+            /** @defgroup scm-globalenv-printable-facet **/
+            ///@{
+
+            bool pretty(const ppindentinfo & ppii) const;
+
+            ///@}
+
+        private:
+
+            /** symbol table assigns a unique index for each symbol **/
+            DGlobalSymtab * symtab_;
+
+            /** value for a symbol S will be in values_[symtab->lookup_binding(S)] **/
+            DArray * values_ = nullptr;
+        };
+    }
+}