xo-interpreter2 stack: work on runtime error representation [WIP]

xo-object2/include/xo/object2/DRuntimeError.hpp

@@ -0,0 +1,61 @@
+/** @file DRuntimeError.hpp
+ *
+ *  @author Roland Conybeare, Feb 2026
+ **/
+
+#pragma once
+
+#include "String.hpp"
+#include <xo/alloc2/Allocator.hpp>
+
+namespace xo {
+    namespace scm {
+
+        /** @brief representation for runtime errors
+         **/
+        class DRuntimeError {
+        public:
+            using ACollector = xo::mm::ACollector;
+            using AAllocator = xo::mm::AAllocator;
+            using ppindentinfo = xo::print::ppindentinfo;
+
+        public:
+            /** create instance using memory from allocator @p mm
+             *  @p src_fn identifies the (c++) function/method in which
+             *  error detercted.
+             *  @p error_descr contains human-readable error message;
+             *  will be copied by this function.
+             **/
+            DRuntimeError * _make(obj<AAllocator> mm,
+                                  DString * src_fn,
+                                  DString * error_descr);
+
+            /** @defgroup scm-runtimeerror-printable-facet printable facet **/
+            ///@{
+            
+            bool pretty(const ppindentinfo & ppii) const;
+
+            ///@}
+            /** @defgroup scm-runtimeerror-gcobject-facet gcobject facet **/
+            ///@{
+
+            std::size_t shallow_size() const noexcept;
+            DRuntimeError * shallow_copy(obj<AAllocator> mm) const noexcept;
+            std::size_t forward_children(obj<ACollector> gc) noexcept;
+
+            ///@}
+
+        private:
+            DRuntimeError(DString * src_fn, DString * error_descr);
+
+        private:
+            /** source location at which error identified **/
+            DString * src_function_ = nullptr;
+            /** error description (allocated from ErrorArena) **/
+            DString * error_descr_ = nullptr;
+        };
+
+    } /*namespace scm*/
+} /*namespace xo*/
+
+/* end DRuntimeError.hpp */