godot-cpp/include/godot_cpp/core/class_db.hpp

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/*  class_db.hpp                                                          */
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#ifndef GODOT_CLASS_DB_HPP
#define GODOT_CLASS_DB_HPP

#include <gdextension_interface.h>

#include <godot_cpp/core/defs.hpp>
#include <godot_cpp/core/error_macros.hpp>
#include <godot_cpp/core/method_bind.hpp>
#include <godot_cpp/core/object.hpp>

#include <godot_cpp/classes/class_db_singleton.hpp>

#include <list>
#include <set>
#include <string>
#include <unordered_map>
#include <vector>

// Needed to use StringName as key in `std::unordered_map`
template <>
struct std::hash<godot::StringName> {
	std::size_t operator()(godot::StringName const &s) const noexcept {
		return s.hash();
	}
};

namespace godot {

#define DEFVAL(m_defval) (m_defval)

struct MethodDefinition {
	StringName name;
	std::list<StringName> args;
	MethodDefinition() {}
	MethodDefinition(StringName p_name) :
			name(p_name) {}
};

MethodDefinition D_METHOD(StringName p_name);
MethodDefinition D_METHOD(StringName p_name, StringName p_arg1);
template <typename... Args>
MethodDefinition D_METHOD(StringName p_name, StringName p_arg1, Args... args) {
	MethodDefinition md = D_METHOD(p_name, args...);
	md.args.push_front(p_arg1);
	return md;
}

class ClassDB {
	static GDExtensionInitializationLevel current_level;

	friend class godot::GDExtensionBinding;

public:
	struct PropertySetGet {
		int index;
		StringName setter;
		StringName getter;
		MethodBind *_setptr;
		MethodBind *_getptr;
		Variant::Type type;
	};

	struct ClassInfo {
		StringName name;
		StringName parent_name;
		GDExtensionInitializationLevel level = GDEXTENSION_INITIALIZATION_SCENE;
		std::unordered_map<StringName, MethodBind *> method_map;
		std::set<StringName> signal_names;
		std::unordered_map<StringName, GDExtensionClassCallVirtual> virtual_methods;
		std::set<StringName> property_names;
		std::set<StringName> constant_names;
		// Pointer to the parent custom class, if any. Will be null if the parent class is a Godot class.
		ClassInfo *parent_ptr = nullptr;
	};

private:
	// This may only contain custom classes, not Godot classes
	static std::unordered_map<StringName, ClassInfo> classes;
	static std::unordered_map<StringName, const GDExtensionInstanceBindingCallbacks *> instance_binding_callbacks;
	// Used to remember the custom class registration order.
	static std::vector<StringName> class_register_order;

	static MethodBind *bind_methodfi(uint32_t p_flags, MethodBind *p_bind, const MethodDefinition &method_name, const void **p_defs, int p_defcount);
	static void initialize_class(const ClassInfo &cl);
	static void bind_method_godot(const StringName &p_class_name, MethodBind *p_method);

	template <typename T, bool is_abstract>
	static void _register_class(bool p_virtual = false);

public:
	template <typename T>
	static void register_class(bool p_virtual = false);
	template <typename T>
	static void register_abstract_class();

	_FORCE_INLINE_ static void _register_engine_class(const StringName &p_name, const GDExtensionInstanceBindingCallbacks *p_callbacks) {
		instance_binding_callbacks[p_name] = p_callbacks;
	}

	template <typename N, typename M, typename... VarArgs>
	static MethodBind *bind_method(N p_method_name, M p_method, VarArgs... p_args);

	template <typename N, typename M, typename... VarArgs>
	static MethodBind *bind_static_method(StringName p_class, N p_method_name, M p_method, VarArgs... p_args);

	template <typename M>
	static MethodBind *bind_vararg_method(uint32_t p_flags, StringName p_name, M p_method, const MethodInfo &p_info = MethodInfo(), const std::vector<Variant> &p_default_args = std::vector<Variant>{}, bool p_return_nil_is_variant = true);

	static void add_property_group(const StringName &p_class, const String &p_name, const String &p_prefix);
	static void add_property_subgroup(const StringName &p_class, const String &p_name, const String &p_prefix);
	static void add_property(const StringName &p_class, const PropertyInfo &p_pinfo, const StringName &p_setter, const StringName &p_getter, int p_index = -1);
	static void add_signal(const StringName &p_class, const MethodInfo &p_signal);
	static void bind_integer_constant(const StringName &p_class_name, const StringName &p_enum_name, const StringName &p_constant_name, GDExtensionInt p_constant_value, bool p_is_bitfield = false);
	static void bind_virtual_method(const StringName &p_class, const StringName &p_method, GDExtensionClassCallVirtual p_call);

	static MethodBind *get_method(const StringName &p_class, const StringName &p_method);

	static GDExtensionClassCallVirtual get_virtual_func(void *p_userdata, GDExtensionConstStringNamePtr p_name);
	static const GDExtensionInstanceBindingCallbacks *get_instance_binding_callbacks(const StringName &p_class);

	static void initialize(GDExtensionInitializationLevel p_level);
	static void deinitialize(GDExtensionInitializationLevel p_level);

	CLASSDB_SINGLETON_FORWARD_METHODS;
};

#define BIND_CONSTANT(m_constant) \
	::godot::ClassDB::bind_integer_constant(get_class_static(), "", #m_constant, m_constant);

#define BIND_ENUM_CONSTANT(m_constant) \
	::godot::ClassDB::bind_integer_constant(get_class_static(), ::godot::_gde_constant_get_enum_name(m_constant, #m_constant), #m_constant, m_constant);

#define BIND_BITFIELD_FLAG(m_constant) \
	::godot::ClassDB::bind_integer_constant(get_class_static(), ::godot::_gde_constant_get_bitfield_name(m_constant, #m_constant), #m_constant, m_constant, true);

#define BIND_VIRTUAL_METHOD(m_class, m_method)                                                                                                \
	{                                                                                                                                         \
		auto _call##m_method = [](GDExtensionObjectPtr p_instance, const GDExtensionConstTypePtr *p_args, GDExtensionTypePtr p_ret) -> void { \
			call_with_ptr_args(reinterpret_cast<m_class *>(p_instance), &m_class::m_method, p_args, p_ret);                                   \
		};                                                                                                                                    \
		::godot::ClassDB::bind_virtual_method(m_class::get_class_static(), #m_method, _call##m_method);                                       \
	}

template <typename T, bool is_abstract>
void ClassDB::_register_class(bool p_virtual) {
	static_assert(TypesAreSame<typename T::self_type, T>::value, "Class not declared properly, please use GDCLASS.");
	static_assert(!FunctionsAreSame<T::self_type::_bind_methods, T::parent_type::_bind_methods>::value, "Class must declare 'static void _bind_methods'.");
	static_assert(!std::is_abstract_v<T> || is_abstract, "Class is abstract, please use GDREGISTER_ABSTRACT_CLASS.");
	instance_binding_callbacks[T::get_class_static()] = &T::_gde_binding_callbacks;

	// Register this class within our plugin
	ClassInfo cl;
	cl.name = T::get_class_static();
	cl.parent_name = T::get_parent_class_static();
	cl.level = current_level;
	std::unordered_map<StringName, ClassInfo>::iterator parent_it = classes.find(cl.parent_name);
	if (parent_it != classes.end()) {
		// Assign parent if it is also a custom class
		cl.parent_ptr = &parent_it->second;
	}
	classes[cl.name] = cl;
	class_register_order.push_back(cl.name);

	// Register this class with Godot
	GDExtensionClassCreationInfo class_info = {
		p_virtual, // GDExtensionBool is_virtual;
		is_abstract, // GDExtensionBool is_abstract;
		T::set_bind, // GDExtensionClassSet set_func;
		T::get_bind, // GDExtensionClassGet get_func;
		T::get_property_list_bind, // GDExtensionClassGetPropertyList get_property_list_func;
		T::free_property_list_bind, // GDExtensionClassFreePropertyList free_property_list_func;
		T::property_can_revert_bind, // GDExtensionClassPropertyCanRevert property_can_revert_func;
		T::property_get_revert_bind, // GDExtensionClassPropertyGetRevert property_get_revert_func;
		T::notification_bind, // GDExtensionClassNotification notification_func;
		T::to_string_bind, // GDExtensionClassToString to_string_func;
		nullptr, // GDExtensionClassReference reference_func;
		nullptr, // GDExtensionClassUnreference unreference_func;
		T::create, // GDExtensionClassCreateInstance create_instance_func; /* this one is mandatory */
		T::free, // GDExtensionClassFreeInstance free_instance_func; /* this one is mandatory */
		&ClassDB::get_virtual_func, // GDExtensionClassGetVirtual get_virtual_func;
		nullptr, // GDExtensionClassGetRID get_rid;
		(void *)&T::get_class_static(), // void *class_userdata;
	};

	internal::gdextension_interface_classdb_register_extension_class(internal::library, cl.name._native_ptr(), cl.parent_name._native_ptr(), &class_info);

	// call bind_methods etc. to register all members of the class
	T::initialize_class();

	// now register our class within ClassDB within Godot
	initialize_class(classes[cl.name]);
}

template <typename T>
void ClassDB::register_class(bool p_virtual) {
	ClassDB::_register_class<T, false>(p_virtual);
}

template <typename T>
void ClassDB::register_abstract_class() {
	ClassDB::_register_class<T, true>();
}

template <typename N, typename M, typename... VarArgs>
MethodBind *ClassDB::bind_method(N p_method_name, M p_method, VarArgs... p_args) {
	Variant args[sizeof...(p_args) + 1] = { p_args..., Variant() }; // +1 makes sure zero sized arrays are also supported.
	const Variant *argptrs[sizeof...(p_args) + 1];
	for (uint32_t i = 0; i < sizeof...(p_args); i++) {
		argptrs[i] = &args[i];
	}
	MethodBind *bind = create_method_bind(p_method);
	return bind_methodfi(METHOD_FLAGS_DEFAULT, bind, p_method_name, sizeof...(p_args) == 0 ? nullptr : (const void **)argptrs, sizeof...(p_args));
}

template <typename N, typename M, typename... VarArgs>
MethodBind *ClassDB::bind_static_method(StringName p_class, N p_method_name, M p_method, VarArgs... p_args) {
	Variant args[sizeof...(p_args) + 1] = { p_args..., Variant() }; // +1 makes sure zero sized arrays are also supported.
	const Variant *argptrs[sizeof...(p_args) + 1];
	for (uint32_t i = 0; i < sizeof...(p_args); i++) {
		argptrs[i] = &args[i];
	}
	MethodBind *bind = create_static_method_bind(p_method);
	bind->set_instance_class(p_class);
	return bind_methodfi(0, bind, p_method_name, sizeof...(p_args) == 0 ? nullptr : (const void **)argptrs, sizeof...(p_args));
}

template <typename M>
MethodBind *ClassDB::bind_vararg_method(uint32_t p_flags, StringName p_name, M p_method, const MethodInfo &p_info, const std::vector<Variant> &p_default_args, bool p_return_nil_is_variant) {
	MethodBind *bind = create_vararg_method_bind(p_method, p_info, p_return_nil_is_variant);
	ERR_FAIL_NULL_V(bind, nullptr);

	bind->set_name(p_name);
	bind->set_default_arguments(p_default_args);

	StringName instance_type = bind->get_instance_class();

	std::unordered_map<StringName, ClassInfo>::iterator type_it = classes.find(instance_type);
	if (type_it == classes.end()) {
		memdelete(bind);
		ERR_FAIL_V_MSG(nullptr, String("Class '{0}' doesn't exist.").format(Array::make(instance_type)));
	}

	ClassInfo &type = type_it->second;

	if (type.method_map.find(p_name) != type.method_map.end()) {
		memdelete(bind);
		ERR_FAIL_V_MSG(nullptr, String("Binding duplicate method: {0}::{1}.").format(Array::make(instance_type, p_method)));
	}

	// register our method bind within our plugin
	type.method_map[p_name] = bind;

	// and register with godot
	bind_method_godot(type.name, bind);

	return bind;
}

#define GDREGISTER_CLASS(m_class) ClassDB::register_class<m_class>();
#define GDREGISTER_VIRTUAL_CLASS(m_class) ClassDB::register_class<m_class>(true);
#define GDREGISTER_ABSTRACT_CLASS(m_class) ClassDB::register_abstract_class<m_class>();

} // namespace godot

CLASSDB_SINGLETON_VARIANT_CAST;

#endif // GODOT_CLASS_DB_HPP