feat(lua): added instance property and child access via reference

core/src/datatypes/meta.cpp

@@ -17,6 +17,12 @@ void Data::Variant::Serialize(pugi::xml_node node) const {
     }, this->wrapped);
 }
 
+void Data::Variant::PushLuaValue(lua_State* state) const {
+    return std::visit([&](auto&& it) {
+        return it.PushLuaValue(state);
+    }, this->wrapped);
+}
+
 Data::Variant Data::Variant::Deserialize(pugi::xml_node node) {
     if (Data::TYPE_MAP.count(node.name()) == 0) {
         Logger::fatalErrorf("Unknown type for instance: '%s'", node.name());

core/src/datatypes/meta.h

@@ -37,6 +37,7 @@ namespace Data {
         Data::String ToString() const;
         
         void Serialize(pugi::xml_node node) const;
+        void PushLuaValue(lua_State* state) const;
         static Data::Variant Deserialize(pugi::xml_node node);
     };
 

core/src/datatypes/ref.cpp

@@ -1,8 +1,11 @@
 #include "datatypes/ref.h"
-#include "color3.h"
+#include "datatypes/base.h"
+#include "logger.h"
 #include "meta.h" // IWYU pragma: keep
 #include <memory>
+#include <optional>
 #include "objects/base/instance.h"
+#include "lua.h"
 
 Data::InstanceRef::InstanceRef() {};
 Data::InstanceRef::InstanceRef(std::weak_ptr<Instance> instance) : ref(instance) {};
@@ -33,7 +36,61 @@ void Data::InstanceRef::Serialize(pugi::xml_node node) const {
 //     return Color3::FromHex(node.text().get());
 // }
 
+static int inst_gc(lua_State*);
+static int inst_index(lua_State*);
+static const struct luaL_Reg metatable [] = {
+    {"__gc", inst_gc},
+    {"__index", inst_index},
+    {NULL, NULL} /* end of array */
+};
+
 void Data::InstanceRef::PushLuaValue(lua_State* L) const {
-    // TODO:
-    panic();
+    if (ref.expired()) return lua_pushnil(L);
+
+    int n = lua_gettop(L);
+
+    auto userdata = (std::shared_ptr<Instance>**)lua_newuserdata(L, sizeof(void*));
+
+    // Create new pointer, and assign userdata a pointer to it
+    std::shared_ptr<Instance>* ptr = new std::shared_ptr<Instance>(ref);
+    *userdata = ptr;
+
+    // Create the instance's metatable
+    luaL_newmetatable(L, "__mt_instance");
+    luaL_register(L, NULL, metatable);
+
+    lua_setmetatable(L, n+1);
+}
+
+static int inst_gc(lua_State* L) {
+    // Destroy the contained shared_ptr
+    auto userdata = (std::shared_ptr<Instance>**)lua_touserdata(L, -1);
+    delete *userdata;
+    lua_pop(L, 1);
+
+    return 0;
+}
+
+static int inst_index(lua_State* L) {
+    auto userdata = (std::shared_ptr<Instance>**)lua_touserdata(L, 1);
+    std::shared_ptr<Instance> inst = **userdata;
+    std::string key(lua_tostring(L, 2));
+    lua_pop(L, 2);
+    
+    // Read property
+    std::optional<PropertyMeta> meta = inst->GetPropertyMeta(key);
+    if (meta) {
+        Data::Variant value = inst->GetPropertyValue(key).expect();
+        value.PushLuaValue(L);
+        return 1;
+    }
+
+    // Look for child
+    std::optional<std::shared_ptr<Instance>> child = inst->FindFirstChild(key);
+    if (child) {
+        Data::InstanceRef(child.value()).PushLuaValue(L);
+        return 1;
+    }
+
+    return luaL_error(L, "'%s' is not a valid member of %s", key.c_str(), inst->GetClass()->className.c_str());
 }

core/src/objects/base/instance.cpp

@@ -154,6 +154,14 @@ bool Instance::IsA(std::string className) {
     return cur != nullptr;
 }
 
+std::optional<std::shared_ptr<Instance>> Instance::FindFirstChild(std::string name) {
+    for (auto child : children) {
+        if (child->name == name)
+            return child;
+    }
+    return std::nullopt;
+}
+
 static std::shared_ptr<Instance> DUMMY_INSTANCE;
 DescendantsIterator Instance::GetDescendantsStart() {
     return DescendantsIterator(GetChildren().size() > 0 ? GetChildren()[0] : DUMMY_INSTANCE);

core/src/objects/base/instance.h

@@ -102,6 +102,7 @@ public:
     DescendantsIterator GetDescendantsEnd();
     // Utility functions
     inline void AddChild(std::shared_ptr<Instance> object) { object->SetParent(this->shared_from_this()); }
+    std::optional<std::shared_ptr<Instance>> FindFirstChild(std::string);
 
     // Properties
     result<Data::Variant, MemberNotFound> GetPropertyValue(std::string name);

core/src/objects/script.cpp

@@ -3,8 +3,8 @@
 #include "objects/base/instance.h"
 #include "objects/base/member.h"
 #include "objects/script/scriptcontext.h"
-#include <luajit-2.1/lauxlib.h>
-#include <luajit-2.1/lua.h>
+#include "objects/workspace.h"
+#include "lua.h"
 
 const InstanceType Script::TYPE = {
     .super = &Instance::TYPE,
@@ -40,7 +40,17 @@ void Script::Run() {
     lua_State* L = dataModel().value()->GetService<ScriptContext>()->state;
 
     // Initialize script globals
+    lua_getglobal(L, "_G");
     
+    lua_pushstring(L, "game");
+    Data::InstanceRef(dataModel().value()).PushLuaValue(L);
+    lua_rawset(L, -3);
+
+    lua_pushstring(L, "workspace");
+    Data::InstanceRef(dataModel().value()->GetService<Workspace>()).PushLuaValue(L);
+    lua_rawset(L, -3);
+
+    lua_pop(L, 1);
 
     luaL_loadstring(L, source.c_str());
     int status = lua_pcall(L, 0, LUA_MULTRET, 0);