From 8c0bf6a3112834274de827759a27ea69e1ff362e Mon Sep 17 00:00:00 2001
From: Roland Conybeare <rconybeare@gmail.com>
Date: Fri, 13 Feb 2026 20:46:53 -0500
Subject: [PATCH] xo-interpreter2: work on global symtab [WIP]

---
 include/xo/expression2/DGlobalSymtab.hpp | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/include/xo/expression2/DGlobalSymtab.hpp b/include/xo/expression2/DGlobalSymtab.hpp
index bb668ff3..91117888 100644
--- a/include/xo/expression2/DGlobalSymtab.hpp
+++ b/include/xo/expression2/DGlobalSymtab.hpp
@@ -6,6 +6,7 @@
 #pragma once
 
 #include "Binding.hpp"
+#include <xo/arena/DArenaHashMap.hpp>
 
 namespace xo {
     namespace scm {
@@ -13,10 +14,21 @@ namespace xo {
 
         /** @class DGlobalSymtab
          *  @brief symbol table for toplevel environment
+         *
+         *  We're using DArenaHashMap to store <key,binding> pairs.
+         *  Both of these are outside GC-space, so we don't need collector
+         *  to traverse these.
          **/
-        struct DGlobalSymtab {
+        class DGlobalSymtab {
         public:
+            using key_type = const DUniqueString *;
+            using value_type = Binding;
+            using repr_type = xo::map::DArenaHashMap<key_type, value_type>;
+            using MemorySizeVisitor = xo::mm::MemorySizeVisitor;
 
+        public:
+            /** visit symtab-owned memory pools; call visitor(info) for each **/
+            void visit_pools(const MemorySizeVisitor & visitor) const;
 
         public:
             /** @defgroup xo-expression2-symboltable-facet symboltable facet**/
@@ -31,6 +43,12 @@ namespace xo {
             ///@}
 
         private:
+            /** next binding will use this global index. See DGlobalEnv **/
+            uint32_t next_binding_ix_ = 0;
+
+            /** map symbols -> bindings **/
+            repr_type map_;
+            
         };
 
     } /*namespace scm*/