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Rework the way custom class instances are created from C++

pull/408/head
Marc Gilleron 2020-05-30 19:20:13 +01:00
parent eacffba9f5
commit 09c8bf94df
1 changed files with 105 additions and 46 deletions
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117
include/core/Godot.hpp
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@ -17,58 +17,117 @@
#include "GodotGlobal.hpp"
#include <GDNativeLibrary.hpp>
#include <NativeScript.hpp>
namespace godot {
namespace detail {
template <class T>
T *as(const Object *obj) {
return (obj) ? (T *)godot::nativescript_api->godot_nativescript_get_userdata(obj->_owner) : nullptr;
}
// Godot classes are wrapped by heap-allocated instances mimicking them through the C API.
// They all inherit `_Wrapped`.
template <class T>
T *get_wrapper(godot_object *obj) {
return (T *)godot::nativescript_1_1_api->godot_nativescript_get_instance_binding_data(godot::_RegisterState::language_index, obj);
}
// Custom class instances are not obtainable by just casting the pointer to the base class they inherit,
// partly because in Godot, scripts are not instances of the classes themselves, they are only attached to them.
// Yet we want to "fake" it as if they were the same entity.
template <class T>
T *get_custom_class_instance(const Object *obj) {
return (obj) ? (T *)godot::nativescript_api->godot_nativescript_get_userdata(obj->_owner) : nullptr;
}
template <class T>
inline T *create_custom_class_instance() {
// Usually, script instances hold a reference to their NativeScript resource.
// that resource is obtained from a `.gdns` file, which in turn exists because
// of the resource system of Godot. We can't cleanly hardcode that here,
// so the easiest for now (though not really clean) is to create new resource instances,
// individually attached to the script instances.
// We cannot use wrappers because of https://github.com/godotengine/godot/issues/39181
// godot::NativeScript *script = godot::NativeScript::_new();
// script->set_library(get_wrapper<godot::GDNativeLibrary>((godot_object *)godot::gdnlib));
// script->set_class_name(T::___get_type_name());
// So we use the C API directly.
static godot_class_constructor script_constructor = godot::api->godot_get_class_constructor("NativeScript");
static godot_method_bind *mb_set_library = godot::api->godot_method_bind_get_method("NativeScript", "set_library");
static godot_method_bind *mb_set_class_name = godot::api->godot_method_bind_get_method("NativeScript", "set_class_name");
godot_object *script = script_constructor();
{
const void *args[] = { godot::gdnlib };
godot::api->godot_method_bind_ptrcall(mb_set_library, script, args, nullptr);
}
{
const String class_name = T::___get_type_name();
const void *args[] = { &class_name };
godot::api->godot_method_bind_ptrcall(mb_set_class_name, script, args, nullptr);
}
// Now to instanciate T, we initially did this, however in case of Reference it returns a variant with refcount
// already initialized, which woud cause inconsistent behavior compared to other classes (we still have to return a pointer).
//Variant instance_variant = script->new_();
//T *instance = godot::get_custom_class_instance<T>(instance_variant);
// So we should do this instead, however while convenient, it uses unnecessary wrapper objects.
// Object *base_obj = T::___new_godot_base();
// base_obj->set_script(script);
// return get_custom_class_instance<T>(base_obj);
// Again using the C API to do exactly what we have to do.
static godot_class_constructor base_constructor = godot::api->godot_get_class_constructor(T::___get_godot_base_class_name());
static godot_method_bind *mb_set_script = godot::api->godot_method_bind_get_method("Object", "set_script");
godot_object *base_obj = base_constructor();
{
const void *args[] = { script };
godot::api->godot_method_bind_ptrcall(mb_set_script, base_obj, args, nullptr);
}
return (T *)godot::nativescript_api->godot_nativescript_get_userdata(base_obj);
}
} // namespace detail
// Used in the definition of a custom class where the base is a Godot class
#define GODOT_CLASS(Name, Base) \
\
public: \
inline static const char *___get_type_name() { return static_cast<const char *>(#Name); } \
enum { ___CLASS_IS_SCRIPT = 1, \
}; \
inline static const char *___get_type_name() { return #Name; } \
enum { ___CLASS_IS_SCRIPT = 1 }; \
inline static const char *___get_godot_base_class_name() { \
return Base::___get_class_name(); \
} \
inline static Name *_new() { \
godot::NativeScript *script = godot::NativeScript::_new(); \
script->set_library(godot::get_wrapper<godot::GDNativeLibrary>((godot_object *)godot::gdnlib)); \
script->set_class_name(#Name); \
Name *instance = godot::as<Name>(script->new_()); \
return instance; \
return godot::detail::create_custom_class_instance<Name>(); \
} \
inline static size_t ___get_id() { return typeid(Name).hash_code(); } \
inline static size_t ___get_base_id() { return typeid(Base).hash_code(); } \
inline static const char *___get_base_type_name() { return Base::___get_class_name(); } \
inline static Object *___get_from_variant(godot::Variant a) { return (godot::Object *)godot::as<Name>(godot::Object::___get_from_variant(a)); } \
inline static godot::Object *___get_from_variant(godot::Variant a) { \
return (godot::Object *)godot::detail::get_custom_class_instance<Name>( \
godot::Object::___get_from_variant(a)); \
} \
\
private:
// Used in the definition of a custom class where the base is another custom class
#define GODOT_SUBCLASS(Name, Base) \
\
public: \
inline static const char *___get_type_name() { return static_cast<const char *>(#Name); } \
enum { ___CLASS_IS_SCRIPT = 1, \
}; \
inline static const char *___get_type_name() { return #Name; } \
enum { ___CLASS_IS_SCRIPT = 1 }; \
inline static const char *___get_godot_base_class_name() { \
return Base::___get_godot_base_class_name(); \
} \
inline static Name *_new() { \
godot::NativeScript *script = godot::NativeScript::_new(); \
script->set_library(godot::get_wrapper<godot::GDNativeLibrary>((godot_object *)godot::gdnlib)); \
script->set_class_name(#Name); \
Name *instance = godot::as<Name>(script->new_()); \
return instance; \
return godot::detail::create_custom_class_instance<Name>(); \
} \
inline static size_t ___get_id() { return typeid(Name).hash_code(); }; \
inline static size_t ___get_base_id() { return typeid(Base).hash_code(); }; \
inline static const char *___get_base_type_name() { return #Base; } \
inline static Object *___get_from_variant(godot::Variant a) { return (godot::Object *)godot::as<Name>(godot::Object::___get_from_variant(a)); } \
inline static const char *___get_base_type_name() { return Base::___get_type_name(); } \
inline static godot::Object *___get_from_variant(godot::Variant a) { \
return (godot::Object *)godot::detail::get_custom_class_instance<Name>( \
godot::Object::___get_from_variant(a)); \
} \
\
private:
@ -316,7 +375,7 @@ void register_property(const char *name, P(T::*var), P default_value, godot_meth
usage = (godot_property_usage_flags)((int)usage | GODOT_PROPERTY_USAGE_SCRIPT_VARIABLE);
if (def_val.get_type() == Variant::OBJECT) {
Object *o = get_wrapper<Object>(def_val.operator godot_object *());
Object *o = detail::get_wrapper<Object>(def_val.operator godot_object *());
if (o && o->is_class("Resource")) {
hint = (godot_property_hint)((int)hint | GODOT_PROPERTY_HINT_RESOURCE_TYPE);
hint_string = o->get_class();
@ -460,7 +519,7 @@ T *Object::cast_to(const Object *obj) {
}
if (godot::_TagDB::is_type_compatible(typeid(T).hash_code(), have_tag)) {
return (T::___CLASS_IS_SCRIPT) ? godot::as<T>(obj) : (T *)obj;
return (T::___CLASS_IS_SCRIPT) ? detail::get_custom_class_instance<T>(obj) : (T *)obj;
} else {
return nullptr;
}