refactor(furvm): remove thing handles

furdb/include/context.hpp

@@ -9,7 +9,7 @@
 struct context {
     furvm::context_p  context = std::make_shared<furvm::context>();
     furvm::mod_h      mod;
-    furvm::executor_h executor;
+    furvm::executor*  executor = nullptr;
     furvm::function_h mainFunction;
 
     bool running = true;

furdb/src/main.cpp

@@ -56,12 +56,11 @@ int main(int argc, char** argv) {
             std::cerr << "Failed to load module " << argv[1] << ": " << ex.what() << '\n';
             return 1;
         }
-        ctx.executor     = ctx.context->emplace_executor(ctx.context);
+        ctx.executor     = &ctx.context->allocate_executor();
         ctx.mainFunction = ctx.mod->function_at("main", furvm::function_sig{});
 
         ctx.mod->set_native_function("println", [](furvm::executor& executor) {
-            auto arg = executor.load_thing(0);
+            print_thing(executor.load_thing(0));
-            print_thing(*arg);
             std::cout << '\n';
         });
 

furvm/include/furvm/context.hpp

@@ -11,6 +11,7 @@
 
 #include <cstddef>
 #include <utility>
+#include <vector>
 
 namespace furvm {
 
@@ -39,15 +40,10 @@ public:
     context(const context&)            = delete;
     context& operator=(const context&) = delete;
 public:
-    /**
-     * @brief Emplaces an executor in the context.
-     *
-     * @param args Arguments forwarded to executor's constructor.
-     * @return A handle to the emplaced executor.
-     */
     template <typename... Args>
-    auto emplace_executor(Args&&... args) {
+    auto& allocate_executor() {
-        return m_executors.emplace_back(std::forward<Args>(args)...);
+        executor executor(this);
+        return m_executors.emplace_back(std::move(executor));
     }
 
     /**
@@ -57,7 +53,7 @@ public:
      * @return A handle to the executor.
      */
     template <typename... Args>
-    auto executor_at(Args&&... args) {
+    auto& executor_at(Args&&... args) {
         return m_executors.at(std::forward<Args>(args)...);
     }
 
@@ -68,57 +64,12 @@ public:
      * @return A handle to the executor.
      */
     template <typename... Args>
-    auto executor_at(Args&&... args) const {
+    const auto& executor_at(Args&&... args) const {
         return m_executors.at(std::forward<Args>(args)...);
     }
 
-    /**
+    const std::vector<executor>& executors() const { return m_executors; }
-     * @brief Erases an executor from the context.
-     *
-     * @param args Id of the executor.
-     */
-    template <typename... Args>
-    void erase_executor(Args&&... args) {
-        m_executors.erase(std::forward<Args>(args)...);
-    }
 public:
-    template <typename... Args>
-    auto emplace_thing(Args&&... args) {
-        return m_things.emplace_back(std::forward<Args>(args)...);
-    }
-
-    /**
-     * @brief Returns a thing from the context.
-     *
-     * @param args Id of the thing.
-     * @return A handle to the thing.
-     */
-    template <typename... Args>
-    auto thing_at(Args&&... args) {
-        return m_things.at(std::forward<Args>(args)...);
-    }
-
-    /**
-     * @brief Returns a thing from the context.
-     *
-     * @param args Id of the thing.
-     * @return A handle to the thing.
-     */
-    template <typename... Args>
-    auto thing_at(Args&&... args) const {
-        return m_things.at(std::forward<Args>(args)...);
-    }
-
-    /**
-     * @brief Erases a thing from the context.
-     *
-     * @param args Id of the thing.
-     */
-    template <typename... Args>
-    void erase_thing(Args&&... args) {
-        m_things.erase(std::forward<Args>(args)...);
-    }
-
     /**
      * @brief Returns context's thing allocator.
      *
@@ -128,9 +79,8 @@ public:
 
     thing_type_store& tt_store() { return m_thingTypeStore; }
 private:
-    handle_container<mod_h>      m_modules;
+    handle_container<mod_h> m_modules;
-    handle_container<thing_h>    m_things;
+    std::vector<executor>   m_executors;
-    handle_container<executor_h> m_executors;
 
     furlang::arena             m_thingArena;
     thing_allocator<std::byte> m_thingAllocator;

furvm/include/furvm/executor.hpp

@@ -32,6 +32,10 @@ static inline executor_flags operator~(executor_flags flags) {
 using executor_callback = std::function<void(executor&)>;
 
 class executor {
+    friend class context;
+private:
+    executor(context* context)
+      : m_context(context) {}
 public:
     /**
      * @brief Executor frame.
@@ -44,17 +48,9 @@ public:
         std::size_t stackBase; /**< Snapshot of the stack size before this frame. */
 
         thing_type*          returnType; /**< Return type. */
-        std::vector<thing_h> variables;  /**< Frame variables. */
+        std::vector<thing<>> variables;  /**< Frame variables. */
     };
 public:
-    /**
-     * @brief Returns a new executor.
-     *
-     * @param context Context.
-     */
-    executor(const context_p& context)
-      : m_context(context) {}
-
     ~executor() = default;
 
     /**
@@ -109,20 +105,10 @@ public:
      *
      * @return The frame.
      */
-    frame frame() const;
+    frame top_frame() const;
 
-    const std::stack<struct frame>& frames() const { return m_frames; }
+    const std::stack<frame>& frames() const { return m_frames; }
 public:
-    /**
-     * @brief Pushes a thing handle onto the stack.
-     *
-     * @param handle Thing handle.
-     */
-    template <typename HandleFwd>
-    void push_thing(HandleFwd&& handle) {
-        m_stack.emplace(std::forward<HandleFwd>(handle));
-    }
-
     /**
      * @brief Pushes a thing onto the stack.
      *
@@ -131,21 +117,25 @@ public:
      * @param thing Thing.
      * @return The pushed handle.
      */
-    thing_h push_thing(class thing<>&& thing);
+    thing<>& push_thing(thing<>&& thing);
+
+    thing<>& push_thing(const thing<>& thing);
 
     /**
      * @brief Pops a thing from the stack.
      *
      * @return A handle to the popped thing.
      */
-    thing_h pop_thing();
+    thing<> pop_thing();
 
     /**
      * @brief Returns the top thing on the stack.
      *
      * @return A handle to the top thing.
      */
-    thing_h thing() const;
+    thing<>& top_thing();
+
+    const thing<>& top_thing() const;
 public:
     /**
      * @brief Stores a thing in a frame variable.
@@ -153,7 +143,7 @@ public:
      * @param variable Id of the variable in which the handle will be put.
      * @param thing Thing handle.
      */
-    void store_thing(variable_t variable, const thing_h& thing);
+    void store_thing(variable_t variable, const thing<>& thing);
 
     /**
      * @brief Stores a thing in a frame variable.
@@ -161,7 +151,7 @@ public:
      * @param variable Id of the variable in which the handle will be put.
      * @param thing Thing handle.
      */
-    void store_thing(variable_t variable, thing_h&& thing);
+    void store_thing(variable_t variable, thing<>&& thing);
 
     /**
      * @brief Returns a thing stored in a variable.
@@ -169,7 +159,9 @@ public:
      * @param variable Id of the variable from which the handle will be fetched.
      * @return A handle stored in the variable.
      */
-    thing_h load_thing(variable_t variable) const;
+    thing<>& load_thing(variable_t variable);
+
+    const thing<>& load_thing(variable_t variable) const;
 public:
     /**
      * @brief Executes next instruction.
@@ -179,12 +171,14 @@ private:
     thing_type thing_type_impl(mod_h mod, mod_type type) const;
 
     thing_type* mod_to_thing_type(const mod_h& mod, const mod_type& type) const;
+
+    thing<> make_reference(const thing<>& thing) const;
 private:
     executor_flags m_flags{}; // NOLINT(bugprone-invalid-enum-default-initialization)
-    context_p      m_context;
+    context*       m_context;
 
-    std::stack<struct frame> m_frames;
+    std::stack<frame>   m_frames;
-    std::stack<thing_h>      m_stack;
+    std::stack<thing<>> m_stack;
 
     executor_callback m_newFrameCb = nullptr;
 };

furvm/include/furvm/fwd.hpp

@@ -169,11 +169,6 @@ class thing;
  */
 using thing_id = std::uint32_t;
 
-/**
- * @brief A handle to a thing.
- */
-using thing_h = handle<thing<thing_allocator>, refcount_header<thing_id>>;
-
 // executor.hpp
 
 /**
@@ -195,21 +190,11 @@ enum class executor_flags : std::uint32_t;
  */
 class executor;
 
-/**
- * @brief An alias to a executor shared pointer.
- */
-using executor_p = std::shared_ptr<executor>;
-
 /**
  * @brief Furvm executor's index.
  */
 using executor_id = std::uint32_t;
 
-/**
- * @brief A handle to an executor.
- */
-using executor_h = handle<executor, refcount_header<executor_id>>;
-
 // context.hpp
 
 /**

furvm/include/furvm/thing.hpp

@@ -49,7 +49,7 @@ struct thing_type {
         Array,
 
         Count,
-    } type;
+    } type = Count;
     union value {
         std::nullptr_t null = nullptr;
         thing_type*    typeRef;
@@ -202,6 +202,8 @@ public:
         std::byte*  data;
     };
 public:
+    thing() {}
+
     /**
      * @brief Constructs a thing.
      *
@@ -239,6 +241,7 @@ public:
     thing& operator=(thing&& other) noexcept {
         if (this == &other) return *this;
         m_type            = other.m_type;
+        m_size            = other.m_size;
         m_data            = other.m_data;
         m_allocator       = std::move(other.m_allocator);
         other.m_type.type = thing_type::Count;
@@ -247,8 +250,32 @@ public:
         return *this;
     }
 
-    thing(const thing&)            = delete;
+    thing(const thing& other)
-    thing& operator=(const thing&) = delete;
+      : m_type(other.m_type), m_size(other.m_size), m_allocator(other.m_allocator) {
+        if (m_type.type == thing_type::Ref) {
+            m_data = other.m_data;
+            return;
+        }
+        m_data = m_allocator.allocate(m_size);
+        other.copy(*this);
+    }
+
+    thing& operator=(const thing& other) {
+        if (this == &other) return *this;
+
+        m_type      = other.m_type;
+        m_size      = other.m_size;
+        m_allocator = std::move(other.m_allocator);
+
+        if (m_type.type == thing_type::Ref) {
+            m_data = other.m_data;
+            return *this;
+        }
+        m_data = m_allocator.allocate(m_size);
+        other.copy(*this);
+
+        return *this;
+    }
 public:
     /**
      * @brief Returns a clone of the thing.
@@ -257,6 +284,10 @@ public:
      */
     thing clone() const {
         thing res(m_type, m_allocator);
+        copy(res);
+    }
+private:
+    void copy(thing<>& dst) const {
         switch (m_type.type) {
         case thing_type::S8:
         case thing_type::S16:
@@ -266,9 +297,9 @@ public:
         case thing_type::U16:
         case thing_type::U32:
         case thing_type::U64:
-        case thing_type::Ptr: std::memcpy(res.m_data, m_data, m_size); return std::move(res);
+        case thing_type::Ptr: std::memcpy(dst.m_data, m_data, m_size); return;
-        case thing_type::Array: copy_list(m_type, res.m_data, m_data); return std::move(res);
+        case thing_type::Array: copy_list(m_type, dst.m_data, m_data); return;
-        case thing_type::Ref: throw std::runtime_error("cannot clone references");
+        case thing_type::Ref: throw std::runtime_error("cannot copy references");
         case thing_type::Count: break;
         }
         throw std::runtime_error("unreachable");
@@ -460,17 +491,17 @@ public:
     thing at(thing_type::u64 index) const {
         if (!is(thing_type::Array)) throw bad_thing_access();
 
-        std::size_t elementSize = compute_size_na(*m_type.value.array.type);
+        std::size_t elementSize = compute_size_na(*true_type().value.array.type);
-        if (m_type.value.array.size == 0) {
+        if (true_type().value.array.size == 0) {
             auto& array = get<dynamic_array>();
             if (index < 0 || index >= array.size) throw std::out_of_range("index out of range");
-            thing ref  = { { thing_type::Ref, m_type.value.array.type }, m_allocator };
+            thing ref  = { { thing_type::Ref, true_type().value.array.type }, m_allocator };
             ref.m_data = array.data + (index * elementSize);
             return ref;
         }
 
-        if (index < 0 || index >= m_type.value.array.size) throw std::out_of_range("index out of range");
+        if (index < 0 || index >= true_type().value.array.size) throw std::out_of_range("index out of range");
-        thing ref  = { { thing_type::Ref, m_type.value.array.type }, m_allocator };
+        thing ref  = { { thing_type::Ref, true_type().value.array.type }, m_allocator };
         ref.m_data = m_data + (index * elementSize);
         return ref;
     }
@@ -727,8 +758,8 @@ private:
     }
 private:
     thing_type  m_type;
-    std::size_t m_size;
+    std::size_t m_size = 0;
-    std::byte*  m_data;
+    std::byte*  m_data = nullptr;
 
     allocator_type m_allocator;
 };

furvm/include/furvm/thing_allocator.hpp

@@ -16,6 +16,8 @@ class thing_allocator {
 public:
     using value_type = T; /**< Value type. */
 public:
+    thing_allocator() = default;
+
     /**
      * @brief Constructs a thing allocator.
      *
@@ -101,7 +103,7 @@ public:
         return m_arena != other.m_arena || m_deadThings != other.m_deadThings;
     }
 private:
-    furlang::arena* m_arena;
+    furlang::arena* m_arena = nullptr;
 
     std::shared_ptr<dead_things> m_deadThings;
 };

furvm/src/executor.cpp

@@ -10,6 +10,7 @@
 
 #include <cassert>
 #include <cstdint>
+#include <optional>
 #include <stdexcept>
 #include <utility>
 #include <vector>
@@ -45,6 +46,13 @@ thing_type* executor::mod_to_thing_type(const mod_h& mod, const mod_type& type)
     return m_context->tt_store().insert(thingType);
 }
 
+thing<> executor::make_reference(const thing<>& thing) const {
+    furvm::thing<> ref = { (struct thing_type){ thing_type::Ref, m_context->tt_store().insert(thing.type()) },
+        m_context->thing_alloc() };
+    ref.reference(thing);
+    return std::move(ref);
+}
+
 void executor::push_frame(const mod_h& mod, function function) {
     mod_h modInst = mod;
     while (function.type() == function_t::Import) {
@@ -53,11 +61,12 @@ void executor::push_frame(const mod_h& mod, function function) {
     }
 
     auto                 signature = function.signature();
-    std::vector<thing_h> args;
+    std::vector<thing<>> args;
     args.reserve(signature.params.size());
     for (const auto& param : signature.params) {
         auto arg = pop_thing();
-        if (arg->type() != *mod_to_thing_type(mod, *param)) throw std::runtime_error("function argument type mismatch");
+        if (arg.true_type() != *mod_to_thing_type(mod, *param))
+            throw std::runtime_error("function argument type mismatch");
         args.push_back(std::move(arg));
     }
 
@@ -85,48 +94,65 @@ struct executor::frame executor::pop_frame() {
     if (m_frames.empty()) throw stack_underflow();
     struct executor::frame frame = m_frames.top();
     m_frames.pop();
-    thing_h returnValue;
+    std::optional<thing<>> returnValue;
-    if (frame.returnType != nullptr) returnValue = pop_thing();
+    if (frame.returnType != nullptr) {
+        returnValue = pop_thing();
+        if (returnValue->type() != *frame.returnType) throw std::runtime_error("function return type mismatch");
+    }
     if (m_stack.size() != frame.stackBase) throw std::runtime_error("unexhausted stack");
-    if (frame.returnType != nullptr) push_thing(std::move(returnValue));
+    if (returnValue.has_value()) push_thing(std::move(returnValue.value()));
     return frame;
 }
 
-struct executor::frame executor::frame() const {
+struct executor::frame executor::top_frame() const {
     return m_frames.top();
 }
 
-thing_h executor::push_thing(::furvm::thing<>&& thing) {
+thing<>& executor::push_thing(thing<>&& thing) {
-    return m_stack.emplace(m_context->emplace_thing(std::move(thing)));
+    return m_stack.emplace(std::move(thing));
 }
 
-thing_h executor::pop_thing() {
+thing<>& executor::push_thing(const thing<>& thing) {
+    return m_stack.emplace(thing);
+}
+
+thing<> executor::pop_thing() {
     if (m_frames.top().stackBase >= m_stack.size()) throw stack_underflow();
-    thing_h top = std::move(m_stack.top());
+    auto top = std::move(m_stack.top());
     m_stack.pop();
     return std::move(top);
 }
 
-thing_h executor::thing() const {
+thing<>& executor::top_thing() {
     if (m_frames.top().stackBase >= m_stack.size()) throw stack_underflow();
     return m_stack.top();
 }
 
-void executor::store_thing(variable_t variable, const thing_h& thing) {
+const thing<>& executor::top_thing() const {
+    if (m_frames.top().stackBase >= m_stack.size()) throw stack_underflow();
+    return m_stack.top();
+}
+
+void executor::store_thing(variable_t variable, const thing<>& thing) {
     auto& frame = m_frames.top();
     if (frame.variables.size() <= variable) frame.variables.resize(variable + 1);
     frame.variables[variable] = thing;
 }
 
-void executor::store_thing(variable_t variable, thing_h&& thing) {
+void executor::store_thing(variable_t variable, thing<>&& thing) {
     auto& frame = m_frames.top();
     if (frame.variables.size() <= variable) frame.variables.resize(variable + 1);
     frame.variables[variable] = std::move(thing);
 }
 
-thing_h executor::load_thing(variable_t variable) const {
+thing<>& executor::load_thing(variable_t variable) {
+    auto& frame = m_frames.top();
+    return frame.variables[variable];
+}
+
+const thing<>& executor::load_thing(variable_t variable) const {
     const auto& frame = m_frames.top();
-    return { frame.variables[variable] };
+    return frame.variables[variable];
 }
 
 void executor::step() {
@@ -139,27 +165,27 @@ void executor::step() {
     switch (instr.type) {
     case instruction_t::NoOperation: break;
     case instruction_t::PushS8: {
-        push_thing({ (struct thing_type){ thing_type::S8 }, m_context->thing_alloc() })->get<thing_type::s8>() =
+        push_thing({ (struct thing_type){ thing_type::S8 }, m_context->thing_alloc() }).get<thing_type::s8>() =
             instr.arg.s8;
     } break;
     case instruction_t::PushU8: {
-        push_thing({ (struct thing_type){ thing_type::U8 }, m_context->thing_alloc() })->get<thing_type::u8>() =
+        push_thing({ (struct thing_type){ thing_type::U8 }, m_context->thing_alloc() }).get<thing_type::u8>() =
             instr.arg.u8;
     } break;
     case instruction_t::PushS16: {
-        push_thing({ (struct thing_type){ thing_type::S16 }, m_context->thing_alloc() })->get<thing_type::s16>() =
+        push_thing({ (struct thing_type){ thing_type::S16 }, m_context->thing_alloc() }).get<thing_type::s16>() =
             instr.arg.s16;
     } break;
     case instruction_t::PushU16: {
-        push_thing({ (struct thing_type){ thing_type::U16 }, m_context->thing_alloc() })->get<thing_type::u16>() =
+        push_thing({ (struct thing_type){ thing_type::U16 }, m_context->thing_alloc() }).get<thing_type::u16>() =
             instr.arg.u16;
     } break;
     case instruction_t::PushS32: {
-        push_thing({ (struct thing_type){ thing_type::S32 }, m_context->thing_alloc() })->get<thing_type::s32>() =
+        push_thing({ (struct thing_type){ thing_type::S32 }, m_context->thing_alloc() }).get<thing_type::s32>() =
             instr.arg.s8; // NOLINT
     } break;
     case instruction_t::PushU32: {
-        push_thing({ (struct thing_type){ thing_type::U32 }, m_context->thing_alloc() })->get<thing_type::u32>() =
+        push_thing({ (struct thing_type){ thing_type::U32 }, m_context->thing_alloc() }).get<thing_type::u32>() =
             static_cast<thing_type::u32>(instr.arg.u8);
     } break;
     case instruction_t::Array: {
@@ -167,30 +193,30 @@ void executor::step() {
         if (type.type != thing_type::Array || type.value.array.type == nullptr || type.value.array.type == &type)
             throw std::runtime_error("invalid array type");
 
-        auto array = push_thing({ type, m_context->thing_alloc() });
+        auto& array = push_thing({ type, m_context->thing_alloc() });
 
         if (type.value.array.size == 0) {
             auto         sizeThing = pop_thing();
-            std::int64_t size      = sizeThing->integer();
+            std::int64_t size      = sizeThing.integer();
-            array->resize(size);
+            array.resize(size);
         }
     } break;
     case instruction_t::Get: {
         auto index = pop_thing();
         auto array = pop_thing();
-        push_thing(array->at(index->integer()));
+        push_thing(array.at(index.integer()));
     } break;
     case instruction_t::Set: {
         auto element = pop_thing();
         auto index   = pop_thing();
         auto array   = pop_thing();
-        array->at(index->integer()).assign(std::move(element->clone()));
+        array.at(index.integer()).assign(std::move(element));
     } break;
     case instruction_t::Drop: {
         pop_thing();
     } break;
     case instruction_t::Duplicate: {
-        push_thing(thing());
+        push_thing(top_thing());
     } break;
     case instruction_t::Swap: {
         auto thing1 = pop_thing();
@@ -199,79 +225,76 @@ void executor::step() {
         push_thing(std::move(thing2));
     } break;
     case instruction_t::Clone: {
-        push_thing(std::move(thing()->clone()));
+        push_thing(top_thing());
     } break;
     case instruction_t::Reference: {
-        auto thing = pop_thing();
+        push_thing(std::move(make_reference(pop_thing())));
-        push_thing({ (struct thing_type){ thing_type::Ref, m_context->tt_store().insert(thing->type()) },
-                       m_context->thing_alloc() })
-            ->reference(*thing);
     } break;
     case instruction_t::Add: {
         auto rhs = pop_thing();
         auto lhs = pop_thing();
-        push_thing(lhs->add(*rhs));
+        push_thing(lhs.add(rhs));
     } break;
     case instruction_t::Sub: {
         auto rhs = pop_thing();
         auto lhs = pop_thing();
-        push_thing(lhs->sub(*rhs));
+        push_thing(lhs.sub(rhs));
     } break;
     case instruction_t::Mul: {
         auto rhs = pop_thing();
         auto lhs = pop_thing();
-        push_thing(lhs->mul(*rhs));
+        push_thing(lhs.mul(rhs));
     } break;
     case instruction_t::Div: {
         auto rhs = pop_thing();
         auto lhs = pop_thing();
-        push_thing(lhs->div(*rhs));
+        push_thing(lhs.div(rhs));
     } break;
     case instruction_t::Mod: {
         auto rhs = pop_thing();
         auto lhs = pop_thing();
-        push_thing(lhs->mod(*rhs));
+        push_thing(lhs.mod(rhs));
     } break;
     case instruction_t::Equals: {
         auto rhs = pop_thing();
         auto lhs = pop_thing();
-        push_thing(lhs->equals(*rhs));
+        push_thing(lhs.equals(rhs));
     } break;
     case instruction_t::NotEquals: {
         auto rhs = pop_thing();
         auto lhs = pop_thing();
-        push_thing(lhs->not_equals(*rhs));
+        push_thing(lhs.not_equals(rhs));
     } break;
     case instruction_t::LessThan: {
         auto rhs = pop_thing();
         auto lhs = pop_thing();
-        push_thing(lhs->less_than(*rhs));
+        push_thing(lhs.less_than(rhs));
     } break;
     case instruction_t::GreaterThan: {
         auto rhs = pop_thing();
         auto lhs = pop_thing();
-        push_thing(lhs->greater_than(*rhs));
+        push_thing(lhs.greater_than(rhs));
     } break;
     case instruction_t::LessEqual: {
         auto rhs = pop_thing();
         auto lhs = pop_thing();
-        push_thing(lhs->less_equals(*rhs));
+        push_thing(lhs.less_equals(rhs));
     } break;
     case instruction_t::GreaterEqual: {
         auto rhs = pop_thing();
         auto lhs = pop_thing();
-        push_thing(lhs->greater_equals(*rhs));
+        push_thing(lhs.greater_equals(rhs));
     } break;
     case instruction_t::Pointerof: {
         auto thing = pop_thing();
-        auto ptr   = push_thing({ (struct thing_type){ thing_type::Ptr, m_context->tt_store().at(thing->type().id) },
+        push_thing({ (struct thing_type){ thing_type::Ptr, m_context->tt_store().at(thing.type().id) },
-            m_context->thing_alloc() });
+                       m_context->thing_alloc() })
-        ptr->get<void*>() = thing->raw();
+            .get<void*>() = thing.raw();
     } break;
     case instruction_t::Sizeof: {
-        auto thing = pop_thing();
+        auto  thing = pop_thing();
-        auto size  = push_thing({ (struct thing_type){ thing_type::U64 }, m_context->thing_alloc() });
+        auto& size  = push_thing({ (struct thing_type){ thing_type::U64 }, m_context->thing_alloc() });
-        switch (thing->type().type) {
+        switch (thing.type().type) {
         case thing_type::S8:
         case thing_type::S16:
         case thing_type::S32:
@@ -280,25 +303,25 @@ void executor::step() {
         case thing_type::U16:
         case thing_type::U32:
         case thing_type::U64:
-            size->get<thing_type::u64>() = static_cast<thing_type::u64>(thing_type::primitive_size(thing->type().type));
+            size.get<thing_type::u64>() = static_cast<thing_type::u64>(thing_type::primitive_size(thing.type().type));
             break;
-        case thing_type::Ptr: size->get<thing_type::u64>() = static_cast<thing_type::u64>(sizeof(void*)); break;
+        case thing_type::Ptr: size.get<thing_type::u64>() = static_cast<thing_type::u64>(sizeof(void*)); break;
         case thing_type::Array:
             /* TODO: Return actual memory size of the array
              * By the memory size I mean the length times sizeof single element.
              */
-            size->get<thing_type::u64>() = thing->length();
+            size.get<thing_type::u64>() = thing.length();
             break;
         default: throw std::runtime_error("unreachable");
         }
     } break;
     case instruction_t::Lengthof: {
-        auto thing  = pop_thing();
+        auto thing = pop_thing();
-        auto length = push_thing({ (struct thing_type){ thing_type::U64 }, m_context->thing_alloc() });
+        push_thing({ (struct thing_type){ thing_type::U64 }, m_context->thing_alloc() }).get<thing_type::u64>() =
-        length->get<thing_type::u64>() = thing->length();
+            thing.length();
     } break;
     case instruction_t::Load: {
-        push_thing(load_thing(instr.arg.u16));
+        push_thing(make_reference(load_thing(instr.arg.u16)));
     } break;
     case instruction_t::Store: {
         store_thing(instr.arg.u16, std::move(pop_thing()));
@@ -310,7 +333,7 @@ void executor::step() {
         frame.position += instr.arg.s8;
     } break;
     case instruction_t::JumpNotZero: {
-        if (pop_thing()->integer() != 0) frame.position += instr.arg.s8;
+        if (pop_thing().integer() != 0) frame.position += instr.arg.s8;
     } break;
     case instruction_t::Return: {
         pop_frame();

furvm/src/function.cpp

@@ -1,5 +1,6 @@
 #include "furvm/function.hpp"
 
+#include "furlang/utility/hash.hpp"
 #include "furvm/furvm.hpp"
 
 #include <utility>
@@ -100,8 +101,35 @@ function& function::operator=(const function& other) {
 
 namespace detail {
 
+struct mod_type_hash {
+    std::size_t operator()(const mod_type_h& type) const {
+        std::size_t hash = std::hash<decltype(type->type)>{}(type->type);
+        switch (type->type) {
+        case mod_type::S8:
+        case mod_type::S16:
+        case mod_type::S32:
+        case mod_type::S64:
+        case mod_type::U8:
+        case mod_type::U16:
+        case mod_type::U32:
+        case mod_type::U64: return hash;
+        case mod_type::Ptr:
+        case mod_type::Ref: return furlang::utility::hash_combine(hash, type->value.typeRef);
+        case mod_type::Array:
+            hash = furlang::utility::hash_combine(hash, type->value.array.size);
+            return furlang::utility::hash_combine(hash, type->value.array.typeId);
+        case mod_type::Import:
+            hash = furlang::utility::hash_combine(hash,
+                std::hash<decltype(type->value.imprt.modId)>{}(type->value.imprt.modId));
+            return furlang::utility::hash_combine(hash, type->value.imprt.typeId);
+        case mod_type::Count: break;
+        }
+        return hash;
+    }
+};
+
 std::size_t function_sig_hash::operator()(const function_sig& signature) const {
-    return furlang::utility::vector_hash<mod_type_h, detail::handle_hash<mod_type_h>>{}(signature.params);
+    return furlang::utility::vector_hash<mod_type_h, mod_type_hash>{}(signature.params);
 }
 
 } // namespace detail

furvm/src/main.cpp

@@ -10,7 +10,7 @@
 #include <memory>
 #include <sstream>
 
-static void print_thing(const furvm::thing<furvm::thing_allocator>& thing) {
+static void print_thing(const furvm::thing<>& thing) {
     using namespace furvm;
 
     switch (thing.true_type().type) {
@@ -75,16 +75,15 @@ int main(int argc, char** argv) {
     mod->emplace_function(furvm::function_sig{ { u64Type }, u64Type }, "print").dispatch();
 #endif
     mod->set_native_function("println", [](furvm::executor& executor) {
-        auto arg = executor.load_thing(0);
+        print_thing(executor.load_thing(0));
-        print_thing(*arg);
         std::cout << '\n';
     });
 
-    furvm::executor_h executor = context->emplace_executor(context);
+    auto& executor = context->allocate_executor();
-    executor->push_frame(mod, *mainFunc);
+    executor.push_frame(mod, *mainFunc);
 
-    while ((executor->flags() & furvm::executor_flags::Done) != furvm::executor_flags::Done) {
+    while ((executor.flags() & furvm::executor_flags::Done) != furvm::executor_flags::Done) {
-        executor->step();
+        executor.step();
     }
 
     return 0;

furvm/src/module.cpp

@@ -124,7 +124,12 @@ mod mod::load(std::istream& is) {
         case mod_type::Ptr: {
             mod_type_id typeId = 0;
             detail::load(is, typeId);
-            mod.emplace_type(id, typeId).dispatch();
+            mod.emplace_type(id, mod_type::Ptr, typeId).dispatch();
+        } break;
+        case mod_type::Ref: {
+            mod_type_id typeId = 0;
+            detail::load(is, typeId);
+            mod.emplace_type(id, mod_type::Ref, typeId).dispatch();
         } break;
         case mod_type::Array: {
             mod_type_id typeId = 0;