feat(lua): added Instance.new for object creation

Author: m-doescode

core/src/lua/instancelib.cpp

@@ -0,0 +1,77 @@
+#include "objects/base/instance.h"
+#include "datatypes/ref.h"
+#include "luaapis.h" // IWYU pragma: keep
+#include "objects/meta.h"
+#include <memory>
+
+static int lib_Instance_index(lua_State*);
+static int lib_Instance_tostring(lua_State*);
+static const struct luaL_Reg lib_Instance_metatable [] = {
+    {"__index", lib_Instance_index},
+    {"__tostring", lib_Instance_tostring},
+    {NULL, NULL} /* end of array */
+};
+
+static int __lua_impl__Instance__new(lua_State* L) {
+    int n = lua_gettop(L);
+
+    // First argument (className)
+    std::string className = luaL_checkstring(L, 1);
+
+    // [Optional] Second argument (parent)
+    std::shared_ptr<Instance> parent;
+    if (n > 1) {
+        parent = **(std::shared_ptr<Instance>**)luaL_checkudata(L, 2, "__mt_instance");
+    }
+
+    // Look up class name
+    if (INSTANCE_MAP.count(className) == 0)
+        return luaL_error(L, "Attempt to create instance of unknown type '%s'", className.c_str());
+
+    const InstanceType* type = INSTANCE_MAP[className];
+
+    if (type->flags & (INSTANCE_NOTCREATABLE | INSTANCE_SERVICE) || type->constructor == nullptr)
+        return luaL_error(L, "Attempt to create Instance of type '%s', which is not creatable", className.c_str());
+
+    std::shared_ptr<Instance> object = type->constructor();
+    
+    if (parent != nullptr)
+        object->SetParent(parent);
+
+    InstanceRef(object).PushLuaValue(L);
+    return 1;
+}
+
+void Instance::PushLuaLibrary(lua_State* L) {
+    lua_getglobal(L, "_G");
+    lua_pushstring(L, "Instance");
+
+    lua_newuserdata(L, 0);
+
+    // Create the library's metatable
+    luaL_newmetatable(L, "__mt_lib_Instance");
+    luaL_register(L, NULL, lib_Instance_metatable);
+    lua_setmetatable(L, -2);
+
+    lua_rawset(L, -3);
+    lua_pop(L, 1);
+}
+
+
+int lib_Instance_tostring(lua_State* L) {
+    lua_pushstring(L, "Instance");
+    return 1;
+}
+
+static int lib_Instance_index(lua_State* L) {
+    std::string key(lua_tostring(L, 2));
+    lua_pop(L, 2);
+
+    if (key == "new") {
+        lua_pushcfunction(L, __lua_impl__Instance__new);
+        return 1;
+    }
+
+    return luaL_error(L, "%s is not a valid member of %s\n", key.c_str(), "Instance");
+}
+

core/src/objects/base/instance.h

@@ -95,6 +95,7 @@ class Instance : public std::enable_shared_from_this<Instance> {
 
     // Instance is abstract, so it should not implement GetClass directly
     virtual const InstanceType* GetClass() = 0;
+    static void PushLuaLibrary(lua_State*); // Defined in lua/instancelib.cpp
     bool SetParent(std::optional<std::shared_ptr<Instance>> newParent);
     std::optional<std::shared_ptr<Instance>> GetParent();
     bool IsParentLocked();

core/src/objects/service/script/scriptcontext.cpp

@@ -46,6 +46,7 @@ void ScriptContext::InitService() {
     Vector3::PushLuaLibrary(state);
     CFrame::PushLuaLibrary(state);
     Color3::PushLuaLibrary(state);
+    Instance::PushLuaLibrary(state);
 
     // TODO: custom os library
 

editor/script/scriptdocument.cpp

@@ -71,7 +71,7 @@ class ObLuaLexer : public QsciLexerLua {
                 //"foreach foreachi getn "
 
                 // Openblocks extensions
-                "shared require game workspace "
+                "shared require game workspace Instance Instance.new "
 
                 "_G _VERSION getfenv getmetatable ipairs loadstring "
                 "next pairs pcall rawequal rawget rawset select "