From 87ddccd7172bac60a211d011294aa95750479420 Mon Sep 17 00:00:00 2001
From: Roland Conybeare <rconybeare@gmail.com>
Date: Fri, 16 Jan 2026 13:05:58 -0500
Subject: [PATCH] xo-expression2: + DUniqueString, use in StringTable

---
 include/xo/object2/DString.hpp | 23 ++++++++++++++++++++++-
 src/object2/DString.cpp        | 30 ++++++++++++++++++++++++++----
 2 files changed, 48 insertions(+), 5 deletions(-)

diff --git a/include/xo/object2/DString.hpp b/include/xo/object2/DString.hpp
index 2092f7d..f35fe44 100644
--- a/include/xo/object2/DString.hpp
+++ b/include/xo/object2/DString.hpp
@@ -73,11 +73,18 @@ namespace xo {
                                        const char * cstr);
 
             /** create string containing a copy of @p sv.
-             *  Use memory from allocator @p mm
+             *  Use memory from allocator @p mm.
              **/
             static DString * from_view(obj<AAllocator> mm,
                                        std::string_view sv);
 
+            /** create string containing a copy of @p sv.
+             *  Use memory from allocator @p mm via sub_alloc.
+             *  (load-bearing for StringTable)
+             **/
+            static DString * from_view_suballoc(obj<AAllocator> mm,
+                                                std::string_view sv);
+
             /** clone existing string **/
             static DString * clone(obj<AAllocator> mm,
                                    const DString * src);
@@ -244,6 +251,20 @@ namespace xo {
 
             ///@}
 
+        private:
+            /** @defgroup dstring-impl-methods implementation methods **/
+            ///@{
+
+            /** create instance from view @p sv, using memory from @p mm.
+             *  @p suballoc_flag chooses whether to use alloc() or suballoc().
+             *  Load-bearing for StringTable
+             **/
+            static DString * _from_view_aux(obj<AAllocator> mm,
+                                            std::string_view sv,
+                                            bool suballoc_flag);
+
+            ///@}
+
         private:
             /** @defgroup dstring-instance-variables instance variables **/
             ///@{
diff --git a/src/object2/DString.cpp b/src/object2/DString.cpp
index 93bdf5b..ee9885b 100644
--- a/src/object2/DString.cpp
+++ b/src/object2/DString.cpp
@@ -58,16 +58,24 @@ namespace xo {
         }
 
         DString *
-        DString::from_view(obj<AAllocator> mm,
-                           std::string_view sv)
+        DString::_from_view_aux(obj<AAllocator> mm,
+                                std::string_view sv,
+                                bool suballoc_flag)
         {
             size_type len = sv.size();
             size_type cap = len + 1;
 
-            void * mem = mm.alloc(typeseq::id<DString>(),
-                                  sizeof(DString) + cap);
+            auto tseq = typeseq::id<DString>();
+            void * mem = nullptr;
+            size_type mem_z = sizeof(DString) + cap;
+
+            if (suballoc_flag)
+                mem = mm.sub_alloc(mem_z, false /*!complete_flag*/);
+            else
+                mem = mm.alloc(tseq, mem_z);
 
             DString * result = new (mem) DString();
+
             result->capacity_ = cap;
             result->size_ = len;
             std::memcpy(result->chars_, sv.data(), len);
@@ -76,6 +84,20 @@ namespace xo {
             return result;
         }
 
+        DString *
+        DString::from_view(obj<AAllocator> mm,
+                           std::string_view sv)
+        {
+            return _from_view_aux(mm, sv, false /*!suballoc_flag*/);
+        }
+
+        DString *
+        DString::from_view_suballoc(obj<AAllocator> mm,
+                                    std::string_view sv)
+        {
+            return _from_view_aux(mm, sv, true /*suballoc_flag*/);
+        }
+
         DString *
         DString::clone(obj<AAllocator> mm, const DString * src)
         {