xo-interpreter: handle define-expressions.

xo-interpreter/src/interpreter/ExpressionBoxed.cpp

@@ -0,0 +1,59 @@
+/** @file ExpressionBoxed.cpp
+ *
+ *  @author Roland Conybeare, Nov 2025
+ **/
+
+#include "ExpressionBoxed.hpp"
+#include "xo/reflect/Reflect.hpp"
+
+namespace xo {
+    using xo::reflect::Reflect;
+    using xo::reflect::TaggedPtr;
+
+    namespace scm {
+        ExpressionBoxed::ExpressionBoxed(bp<Expression> c) : contents_{c.promote()}
+        {}
+
+        gp<ExpressionBoxed>
+        ExpressionBoxed::make(gc::IAlloc * mm,
+                              bp<Expression> c)
+        {
+            return new (MMPtr(mm)) ExpressionBoxed(c);
+        }
+
+
+        TaggedPtr
+        ExpressionBoxed::self_tp() const
+        {
+            return Reflect::make_tp(const_cast<ExpressionBoxed *>(this));
+        }
+
+        void
+        ExpressionBoxed::display(std::ostream & os) const
+        {
+            os << contents_;
+        }
+
+        std::size_t
+        ExpressionBoxed::_shallow_size() const
+        {
+            return sizeof(ExpressionBoxed);
+        }
+
+        Object *
+        ExpressionBoxed::_shallow_copy(gc::IAlloc * mm) const
+        {
+            Cpof cpof(mm, this);
+
+            return new (cpof) ExpressionBoxed(*this);
+        }
+
+        std::size_t
+        ExpressionBoxed::_forward_children(gc::IAlloc *)
+        {
+            return _shallow_size();
+        }
+    } /*namespace scm*/
+} /*namespace xo*/
+
+/* end ExpressionBoxed.cpp */