feat: introduce reference instruction

furvm/include/furvm/instruction.hpp

@@ -40,6 +40,13 @@ enum class instruction_t : byte {
      */
     Clone,
 
+    /**
+     * @brief Pushes a new reference onto the stack.
+     *
+     * Pops the top thing from the stack and pushes its reference.
+     */
+    Reference,
+
     /**
      * @brief Adds two things together on the stack.
      */

furvm/include/furvm/thing.hpp

@@ -368,7 +368,7 @@ public:
     }
 
     thing reference() const {
-        thing res              = { std::make_shared<type>({ m_type }), m_allocator };
+        thing res              = { std::make_shared<class type>(m_type), m_allocator };
         res.get<reference_t>() = m_data;
         return std::move(res);
     }

furvm/src/executor.cpp

@@ -102,6 +102,10 @@ void executor::step() {
     case instruction_t::Clone: {
         push_thing(std::move(thing()->clone()));
     } break;
+    case instruction_t::Reference: {
+        auto thing = pop_thing();
+        push_thing(std::move(thing->reference()));
+    } break;
     case instruction_t::Add: {
         auto rhs = pop_thing();
         auto lhs = pop_thing();

furvm/src/main.cpp

@@ -8,10 +8,11 @@
 #include <iostream>
 #include <memory>
 
-static constexpr std::array<furvm::byte, 8> s_bytecode = {
+static constexpr std::array<furvm::byte, 9> s_bytecode = {
     furvm::byte(furvm::instruction_t::PushB2I),
     67,
-    furvm::byte(furvm::instruction_t::Clone),
+    furvm::byte(furvm::instruction_t::Duplicate),
+    furvm::byte(furvm::instruction_t::Reference),
     furvm::byte(furvm::instruction_t::Add),
     furvm::byte(furvm::instruction_t::Call),
     1,