refactor(furvm): improve references

Closes: #53

furvm/include/furvm/instruction.hpp

@@ -125,6 +125,11 @@ enum class instruction_t : byte {
      */
     Sizeof,
 
+    /**
+     * @brief Pushes a length of popped-off thing onto the stack.
+     */
+    Lengthof,
+
     /**
      * @brief Pushes a variable onto the stack.
      *

furvm/include/furvm/module.hpp

@@ -37,6 +37,8 @@ struct mod_type {
         U16,
         U32,
         U64,
+        Ptr,
+        Ref,
         Array,
 
         Import,
@@ -44,11 +46,15 @@ struct mod_type {
     } type;
     union value {
         std::nullptr_t null = nullptr;
+        mod_type_id    typeRef;
         array          array;
         imprt          imprt;
 
         value() = default;
 
+        value(mod_type_id id)
+          : typeRef(id) {}
+
         value(mod_type_id id, std::size_t size)
           : array({}) {
             array.typeId = id;
@@ -73,6 +79,9 @@ struct mod_type {
     mod_type(enum type type)
       : type(type) {}
 
+    mod_type(enum type type, mod_type_id typeRef)
+      : type(type), value(typeRef) {}
+
     mod_type(mod_type_id id, std::size_t size)
       : type(Array), value(id, size) {}
 

furvm/include/furvm/thing.hpp

@@ -44,16 +44,22 @@ struct thing_type {
         U16,
         U32,
         U64,
+        Ptr,
+        Ref,
         Array,
 
         Count,
     } type;
     union value {
         std::nullptr_t null = nullptr;
+        thing_type*    typeRef;
         array          array;
 
         value() = default;
 
+        value(thing_type* type)
+          : typeRef(type) {}
+
         value(thing_type* type, std::size_t size)
           : array({}) {
             array.type = type;
@@ -76,6 +82,8 @@ struct thing_type {
         case U16:
         case U32:
         case U64: return true;
+        case Ptr:
+        case Ref: return *value.typeRef == *other.value.typeRef;
         case Array: return *value.array.type == *other.value.array.type && value.array.size == other.value.array.size;
         case Count: break;
         }
@@ -94,10 +102,12 @@ struct thing_type {
         case U16:
         case U32:
         case U64: return true;
-        case Array:
+        case Ptr:
+        case Ref:
+        case Array: return false;
         case Count: break;
         }
-        return false;
+        throw std::runtime_error("unreachable");
     }
 
     static std::size_t primitive_size(enum type type) {
@@ -110,10 +120,12 @@ struct thing_type {
         case thing_type::U16: return sizeof(u16);
         case thing_type::U32: return sizeof(u32);
         case thing_type::U64: return sizeof(u64);
-        case Array:
+        case Ptr:
+        case Ref:
+        case Array: return 0;
         case Count: break;
         }
-        return 0;
+        throw std::runtime_error("unreachable");
     }
 };
 
@@ -131,6 +143,8 @@ struct thing_type_hash {
         case thing_type::U16:
         case thing_type::U32:
         case thing_type::U64: return seed;
+        case thing_type::Ptr:
+        case thing_type::Ref: return furlang::utility::hash_combine(seed, thing_type_hash{}(*type.value.typeRef));
         case thing_type::Array:
             seed = furlang::utility::hash_combine(seed, thing_type_hash{}(*type.value.array.type));
             seed = furlang::utility::hash_combine(seed,
@@ -156,6 +170,16 @@ public:
         return ptr;
     }
 
+    thing_type* insert(const thing_type& type) {
+        if (auto it = m_typeMap.find(type); it != m_typeMap.end()) return m_map[it->second];
+
+        thing_type_id id  = m_counter++;
+        thing_type*   ptr = m_arena.allocate<thing_type>(type);
+        m_map[id]         = ptr;
+        m_typeMap[type]   = id;
+        return ptr;
+    }
+
     thing_type* at(thing_type_id id) const {
         if (auto it = m_map.find(id); it != m_map.end()) return it->second;
         return nullptr;
@@ -189,6 +213,7 @@ public:
      */
     thing(const thing_type& type, const allocator_type& allocator = {})
       : m_type(type), m_size(compute_size(type)), m_allocator(allocator) {
+        if (m_type.type == thing_type::Ref) return;
         // TODO: Account for alignment
         m_data = m_allocator.allocate(m_size);
         std::memset(m_data, 0, m_size);
@@ -198,7 +223,7 @@ public:
      * @brief Destructs a thing.
      */
     ~thing() {
-        if (m_data != nullptr && m_size > 0) m_allocator.deallocate(m_data, m_size);
+        if (m_type.type != thing_type::Ref && m_data != nullptr && m_size > 0) m_allocator.deallocate(m_data, m_size);
     }
 
     /**
@@ -234,8 +259,6 @@ public:
      * @return A clone of this thing.
      */
     thing clone() const {
-        if (m_size == 0) return reference();
-
         thing res(m_type, m_allocator);
         switch (m_type.type) {
         case thing_type::S8:
@@ -245,19 +268,40 @@ public:
         case thing_type::U8:
         case thing_type::U16:
         case thing_type::U32:
-        case thing_type::U64: std::memcpy(res.m_data, m_data, m_size); return std::move(res);
+        case thing_type::U64:
+        case thing_type::Ptr: std::memcpy(res.m_data, m_data, m_size); return std::move(res);
         case thing_type::Array: copy_list(m_type, res.get<array>(), get<array>()); return std::move(res);
+        case thing_type::Ref: throw std::runtime_error("cannot clone references");
         case thing_type::Count: break;
         }
         throw std::runtime_error("unreachable");
     }
 public:
     /**
-     * @brief Returns the thing's type reference.
+     * @brief Returns the thing's type.
      *
-     * @return The type reference.
+     * @return The type.
      */
-    constexpr auto type() const { return m_type; }
+    constexpr thing_type type() const { return m_type; }
+
+    /**
+     * @brief Returns the thing's true type.
+     *
+     * If the thing is a reference, returns the referenced type.
+     *
+     * @return The true type.
+     */
+    constexpr thing_type true_type() const { return (m_type.type == thing_type::Ref) ? *m_type.value.typeRef : m_type; }
+
+    /**
+     * @brief Checks if the thing is of a specified type.
+     *
+     * Compares the true type.
+     *
+     * @param type Type to compare.
+     * @return true if the types match.
+     */
+    constexpr bool is(enum thing_type::type type) const { return true_type().type == type; }
 public:
     /**
      * @brief Returns a raw data pointer.
@@ -402,12 +446,8 @@ public:
         }
     }
 
-    thing reference() const { return { m_type, m_data, m_allocator }; }
-
-    constexpr bool is_reference() const { return m_size == 0; }
-
     void resize(thing_type::u64 newSize) {
-        if (m_type.type != thing_type::Array) throw bad_thing_access();
+        if (!is(thing_type::Array)) throw bad_thing_access();
         if (m_type.value.array.size > 0) throw std::runtime_error("cannot resize a static array");
 
         auto& array = get<union array>();
@@ -423,29 +463,45 @@ public:
     }
 
     thing at(thing_type::u64 index) const {
-        if (m_type.type != thing_type::Array) throw bad_thing_access();
+        if (!is(thing_type::Array)) throw bad_thing_access();
 
         std::size_t elementSize = compute_size_na(*m_type.value.array.type);
         if (m_type.value.array.size == 0) {
             auto& array = get<union array>();
             if (index < 0 || index >= array.dynamic.size) throw std::out_of_range("index out of range");
-            return { *m_type.value.array.type, array.dynamic.data + (index * elementSize), m_allocator };
+            thing ref  = { { thing_type::Ref, m_type.value.array.type }, m_allocator };
+            ref.m_data = array.dynamic.data + (index * elementSize);
+            return ref;
         }
 
         std::byte* data = reinterpret_cast<array*>(m_data)->flat;
         if (index < 0 || index >= m_type.value.array.size) throw std::out_of_range("index out of range");
-        return { *m_type.value.array.type, data + (index * elementSize), m_allocator };
+        thing ref  = { { thing_type::Ref, m_type.value.array.type }, m_allocator };
+        ref.m_data = data + (index * elementSize);
+        return ref;
     }
 
-    std::size_t size() const {
-        if (m_type.type != thing_type::Array) throw bad_thing_access();
-        return m_type.value.array.size == 0 ? get<array>().dynamic.size : m_type.value.array.size;
+    thing_type::u64 length() const {
+        if (!is(thing_type::Array)) throw bad_thing_access();
+        return true_type().value.array.size == 0 ? get<array>().dynamic.size : true_type().value.array.size;
     }
 
     template <typename T, typename = std::enable_if_t<std::is_integral_v<T>>>
     T cast_to() const {
         return visit_primitive([](auto value) { return static_cast<T>(value); });
     }
+
+    /**
+     * @brief Changes reference thing's referenced thing.
+     *
+     * Yes.
+     *
+     * @param thing Thing.
+     */
+    void reference(const thing& thing) {
+        if (m_type.type != thing_type::Ref || *m_type.value.typeRef != thing.type()) throw bad_thing_access();
+        m_data = thing.m_data;
+    }
 private:
     static void copy_list(const thing_type& arrayType, array& dst, const array& src) {
         if (arrayType.type != thing_type::Array || arrayType.value.array.type == nullptr)
@@ -480,7 +536,9 @@ private:
         case thing_type::U8:
         case thing_type::U16:
         case thing_type::U32:
-        case thing_type::U64: std::memcpy(dst.flat, src.flat, size); return;
+        case thing_type::U64:
+        case thing_type::Ptr:
+        case thing_type::Ref: std::memcpy(dst.flat, src.flat, size); return;
         case thing_type::Array:
             for (std::size_t i = 0; i < size; ++i) {
                 copy_list(*innerType.value.array.type,
@@ -503,6 +561,8 @@ private:
         case thing_type::U16: return sizeof(thing_type::u16);
         case thing_type::U32: return sizeof(thing_type::u32);
         case thing_type::U64: return sizeof(thing_type::u64);
+        case thing_type::Ptr: return sizeof(void*);
+        case thing_type::Ref: return compute_size_na(*type.value.typeRef);
         case thing_type::Array:
             return type.value.array.size == 0 ? sizeof(array)
                                               : compute_size_na(*type.value.array.type) * type.value.array.size;
@@ -514,9 +574,6 @@ private:
 
     // NOTE: Align to 4 bytes
     static std::size_t compute_size(const thing_type& type) { return (compute_size_na(type) + 3) & ~3; }
-private:
-    thing(const thing_type& type, std::byte* data, const allocator_type& allocator = {})
-      : m_type(type), m_size(0), m_data(data), m_allocator(allocator) {}
 private:
     template <typename Func>
     decltype(auto) visit_primitive(Func&& func) const {
@@ -611,7 +668,7 @@ private:
                 thing_type::U64,
             };
 
-            enum thing_type::type resultType = promotions[m_type.type + (rhs.m_type.type * 8)];
+            enum thing_type::type resultType = promotions[true_type().type + (rhs.true_type().type * 8)];
 
             thing res = { thing_type{ resultType }, m_allocator };
             switch (resultType) {
@@ -639,6 +696,8 @@ private:
             case thing_type::U64:
                 res.get<thing_type::u64>() = Op{}(cast_to<thing_type::u64>(), rhs.cast_to<thing_type::u64>());
                 return res;
+            case thing_type::Ptr: // TODO: Pointer arithmetics
+            case thing_type::Ref:
             case thing_type::Array:
             case thing_type::Count: break;
             }

furvm/src/executor.cpp

@@ -29,6 +29,7 @@ thing_type executor::thing_type_impl(mod_h mod, mod_type type) const {
     case thing_type::U16:
     case thing_type::U32:
     case thing_type::U64: return { static_cast<enum thing_type::type>(type.type) };
+    case thing_type::Ptr: return { thing_type::Ptr, thing_type(mod, *mod->type_at(type.value.typeRef)) };
     case thing_type::Array: {
         return { static_cast<enum thing_type::type>(type.type),
             { thing_type(mod, *mod->type_at(type.value.array.typeId)), type.value.array.size } };
@@ -164,7 +165,9 @@ void executor::step() {
     } break;
     case instruction_t::Reference: {
         auto thing = pop_thing();
-        push_thing(std::move(thing->reference()));
+        push_thing({ (struct thing_type){ thing_type::Ref, m_context->thing_type_store().insert(thing->type()) },
+                       m_context->thing_alloc() })
+            ->reference(*thing);
     } break;
     case instruction_t::Add: {
         auto rhs = pop_thing();
@@ -222,18 +225,11 @@ void executor::step() {
         push_thing(lhs->greater_equals(*rhs));
     } break;
     case instruction_t::Pointerof: {
-        // auto thing = pop_thing();
-        // auto ptr   = push_thing(
-        //{ (struct thing_type){ thing_type::Primitive, { sizeof(std::uintptr_t) } }, m_context->thing_alloc() });
-        // switch (thing->type().type) {
-        // case thing_type::Primitive: ptr->get<std::uintptr_t>() = reinterpret_cast<std::uintptr_t>(thing->raw());
-        // break; case thing_type::Array: ptr->get<std::uintptr_t>() = reinterpret_cast<std::uintptr_t>(
-        // thing->type().value.array.size == 0 ? thing->get<furvm::thing<>::array>().dynamic.data
-        //: thing->get<furvm::thing<>::array>().flat);
-        // break;
-        // case thing_type::Count: throw std::runtime_error("unreachable");
-        // }
-        throw std::runtime_error("unimplemented"); // TODO: Implement
+        auto thing = pop_thing();
+        auto ptr =
+            push_thing({ (struct thing_type){ thing_type::Ptr, m_context->thing_type_store().at(thing->type().id) },
+                m_context->thing_alloc() });
+        ptr->get<void*>() = thing->raw();
     } break;
     case instruction_t::Sizeof: {
         auto thing = pop_thing();
@@ -249,14 +245,21 @@ void executor::step() {
         case thing_type::U64:
             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::Array:
-            size->get<thing_type::u64>() = static_cast<thing_type::u64>(
-                (thing->type().value.array.size == 0) ? thing->get<furvm::thing<>::array>().dynamic.size
-                                                      : thing->type().value.array.size);
+            /* 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();
             break;
         default: throw std::runtime_error("unreachable");
         }
     } break;
+    case instruction_t::Lengthof: {
+        auto thing  = pop_thing();
+        auto length = push_thing({ (struct thing_type){ thing_type::U64 }, m_context->thing_alloc() });
+        length->get<thing_type::u64>() = thing->length();
+    } break;
     case instruction_t::Load: {
         variable_t variable = static_cast<std::uint16_t>(frame.mod->byte(frame.position)) |
                               (static_cast<std::uint16_t>(frame.mod->byte(frame.position + 1)) << 8);

furvm/src/main.cpp

@@ -24,7 +24,7 @@ static void print_thing(const furvm::thing<furvm::thing_allocator>& thing) {
     case thing_type::U64: std::cout << thing.get<thing_type::u64>(); break;
     case furvm::thing_type::Array:
         std::cout << "{ ";
-        for (thing_type::u64 i = 0; i < thing.size(); ++i) {
+        for (thing_type::u64 i = 0; i < thing.length(); ++i) {
             if (i > 0) std::cout << ", ";
             print_thing(thing.at(i));
         }
@@ -59,6 +59,7 @@ int main(int argc, char** argv) {
         0,
         0,
         static_cast<furvm::byte>(furvm::instruction_t::Reference),
+        static_cast<furvm::byte>(furvm::instruction_t::Lengthof),
         static_cast<furvm::byte>(furvm::instruction_t::Call),
         1,
         0,
@@ -68,8 +69,9 @@ int main(int argc, char** argv) {
     auto mod       = context->emplace("main", s_bytecode, s_bytecode + sizeof(s_bytecode));
     auto charType  = mod->emplace_type(furvm::mod_type::S8);
     auto arrayType = mod->emplace_type(charType.id(), 10);
+    auto u64Type   = mod->emplace_type(furvm::mod_type::U64);
     auto mainFunc  = mod->emplace_function("main", furvm::function_sig{}, 0);
-    mod->emplace_function(furvm::function_sig{ { arrayType } }, "print").dispatch();
+    mod->emplace_function(furvm::function_sig{ { u64Type } }, "print").dispatch();
 #endif
     mod->set_native_function("print", [](furvm::executor& executor) {
         print_thing(*executor.load_thing(0));

furvm/src/module.cpp

@@ -34,6 +34,8 @@ std::ostream& mod::serialize(std::ostream& os) const {
         case mod_type::U16:
         case mod_type::U32:
         case mod_type::U64: break;
+        case mod_type::Ptr:
+        case mod_type::Ref: detail::serialize(os, type.value.typeRef); break;
         case mod_type::Array: {
             detail::serialize(os, type.value.array.typeId);
             detail::serialize(os, type.value.array.size);
@@ -115,6 +117,11 @@ mod mod::load(std::istream& is) {
         case mod_type::U16:
         case mod_type::U32:
         case mod_type::U64: break;
+        case mod_type::Ptr: {
+            mod_type_id typeId = 0;
+            detail::load(is, typeId);
+            mod.emplace_type(id, typeId).dispatch();
+        } break;
         case mod_type::Array: {
             mod_type_id typeId = 0;
             detail::load(is, typeId);