virtualx-engine/core/variant/binder_common.h

/*************************************************************************/
/*  binder_common.h                                                      */
/*************************************************************************/
/*                       This file is part of:                           */
/*                           GODOT ENGINE                                */
/*                      https://godotengine.org                          */
/*************************************************************************/
/* Copyright (c) 2007-2020 Juan Linietsky, Ariel Manzur.                 */
/* Copyright (c) 2014-2020 Godot Engine contributors (cf. AUTHORS.md).   */
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/* Permission is hereby granted, free of charge, to any person obtaining */
/* a copy of this software and associated documentation files (the       */
/* "Software"), to deal in the Software without restriction, including   */
/* without limitation the rights to use, copy, modify, merge, publish,   */
/* distribute, sublicense, and/or sell copies of the Software, and to    */
/* permit persons to whom the Software is furnished to do so, subject to */
/* the following conditions:                                             */
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/* The above copyright notice and this permission notice shall be        */
/* included in all copies or substantial portions of the Software.       */
/*                                                                       */
/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
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/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
/*************************************************************************/

#ifndef BINDER_COMMON_H
#define BINDER_COMMON_H

#include "core/object/object.h"
#include "core/templates/list.h"
#include "core/templates/simple_type.h"
#include "core/typedefs.h"
#include "core/variant/method_ptrcall.h"
#include "core/variant/type_info.h"
#include "core/variant/variant.h"
#include "core/variant/variant_internal.h"

#include <stdio.h>

template <class T>
struct VariantCaster {
	static _FORCE_INLINE_ T cast(const Variant &p_variant) {
		return p_variant;
	}
};

template <class T>
struct VariantCaster<T &> {
	static _FORCE_INLINE_ T cast(const Variant &p_variant) {
		return p_variant;
	}
};

template <class T>
struct VariantCaster<const T &> {
	static _FORCE_INLINE_ T cast(const Variant &p_variant) {
		return p_variant;
	}
};

#ifdef PTRCALL_ENABLED

#define VARIANT_ENUM_CAST(m_enum)                                            \
	MAKE_ENUM_TYPE_INFO(m_enum)                                              \
	template <>                                                              \
	struct VariantCaster<m_enum> {                                           \
		static _FORCE_INLINE_ m_enum cast(const Variant &p_variant) {        \
			return (m_enum)p_variant.operator int();                         \
		}                                                                    \
	};                                                                       \
	template <>                                                              \
	struct PtrToArg<m_enum> {                                                \
		_FORCE_INLINE_ static m_enum convert(const void *p_ptr) {            \
			return m_enum(*reinterpret_cast<const int *>(p_ptr));            \
		}                                                                    \
		_FORCE_INLINE_ static void encode(m_enum p_val, const void *p_ptr) { \
			*(int *)p_ptr = p_val;                                           \
		}                                                                    \
	};

#else

#define VARIANT_ENUM_CAST(m_enum)                                     \
	MAKE_ENUM_TYPE_INFO(m_enum)                                       \
	template <>                                                       \
	struct VariantCaster<m_enum> {                                    \
		static _FORCE_INLINE_ m_enum cast(const Variant &p_variant) { \
			return (m_enum)p_variant.operator int();                  \
		}                                                             \
	};

#endif

// Object enum casts must go here
VARIANT_ENUM_CAST(Object::ConnectFlags);

VARIANT_ENUM_CAST(Vector3::Axis);

VARIANT_ENUM_CAST(Error);
VARIANT_ENUM_CAST(Margin);
VARIANT_ENUM_CAST(Corner);
VARIANT_ENUM_CAST(Orientation);
VARIANT_ENUM_CAST(HAlign);
VARIANT_ENUM_CAST(VAlign);
VARIANT_ENUM_CAST(PropertyHint);
VARIANT_ENUM_CAST(PropertyUsageFlags);
VARIANT_ENUM_CAST(Variant::Type);
VARIANT_ENUM_CAST(Variant::Operator);

template <>
struct VariantCaster<char32_t> {
	static _FORCE_INLINE_ char32_t cast(const Variant &p_variant) {
		return (char32_t)p_variant.operator int();
	}
};
#ifdef PTRCALL_ENABLED
template <>
struct PtrToArg<char32_t> {
	_FORCE_INLINE_ static char32_t convert(const void *p_ptr) {
		return char32_t(*reinterpret_cast<const int *>(p_ptr));
	}
	_FORCE_INLINE_ static void encode(char32_t p_val, const void *p_ptr) {
		*(int *)p_ptr = p_val;
	}
};
#endif

template <typename T>
struct VariantObjectClassChecker {
	static _FORCE_INLINE_ bool check(const Variant &p_variant) {
		return true;
	}
};

template <>
struct VariantObjectClassChecker<Node *> {
	static _FORCE_INLINE_ bool check(const Variant &p_variant) {
		Object *obj = p_variant;
		Node *node = p_variant;
		return node || !obj;
	}
};

template <>
struct VariantObjectClassChecker<Control *> {
	static _FORCE_INLINE_ bool check(const Variant &p_variant) {
		Object *obj = p_variant;
		Control *control = p_variant;
		return control || !obj;
	}
};

#ifdef DEBUG_METHODS_ENABLED

template <class T>
struct VariantCasterAndValidate {
	static _FORCE_INLINE_ T cast(const Variant **p_args, uint32_t p_arg_idx, Callable::CallError &r_error) {
		Variant::Type argtype = GetTypeInfo<T>::VARIANT_TYPE;
		if (!Variant::can_convert_strict(p_args[p_arg_idx]->get_type(), argtype) ||
				!VariantObjectClassChecker<T>::check(p_args[p_arg_idx])) {
			r_error.error = Callable::CallError::CALL_ERROR_INVALID_ARGUMENT;
			r_error.argument = p_arg_idx;
			r_error.expected = argtype;
		}

		return VariantCaster<T>::cast(*p_args[p_arg_idx]);
	}
};

template <class T>
struct VariantCasterAndValidate<T &> {
	static _FORCE_INLINE_ T cast(const Variant **p_args, uint32_t p_arg_idx, Callable::CallError &r_error) {
		Variant::Type argtype = GetTypeInfo<T>::VARIANT_TYPE;
		if (!Variant::can_convert_strict(p_args[p_arg_idx]->get_type(), argtype) ||
				!VariantObjectClassChecker<T>::check(p_args[p_arg_idx])) {
			r_error.error = Callable::CallError::CALL_ERROR_INVALID_ARGUMENT;
			r_error.argument = p_arg_idx;
			r_error.expected = argtype;
		}

		return VariantCaster<T>::cast(*p_args[p_arg_idx]);
	}
};

template <class T>
struct VariantCasterAndValidate<const T &> {
	static _FORCE_INLINE_ T cast(const Variant **p_args, uint32_t p_arg_idx, Callable::CallError &r_error) {
		Variant::Type argtype = GetTypeInfo<T>::VARIANT_TYPE;
		if (!Variant::can_convert_strict(p_args[p_arg_idx]->get_type(), argtype) ||
				!VariantObjectClassChecker<T>::check(p_args[p_arg_idx])) {
			r_error.error = Callable::CallError::CALL_ERROR_INVALID_ARGUMENT;
			r_error.argument = p_arg_idx;
			r_error.expected = argtype;
		}

		return VariantCaster<T>::cast(*p_args[p_arg_idx]);
	}
};

#endif // DEBUG_METHODS_ENABLED

template <class T, class... P, size_t... Is>
void call_with_variant_args_helper(T *p_instance, void (T::*p_method)(P...), const Variant **p_args, Callable::CallError &r_error, IndexSequence<Is...>) {
	r_error.error = Callable::CallError::CALL_OK;

#ifdef DEBUG_METHODS_ENABLED
	(p_instance->*p_method)(VariantCasterAndValidate<P>::cast(p_args, Is, r_error)...);
#else
	(p_instance->*p_method)(VariantCaster<P>::cast(*p_args[Is])...);
#endif
	(void)(p_args); //avoid warning
}

template <class T, class... P, size_t... Is>
void call_with_variant_argsc_helper(T *p_instance, void (T::*p_method)(P...) const, const Variant **p_args, Callable::CallError &r_error, IndexSequence<Is...>) {
	r_error.error = Callable::CallError::CALL_OK;

#ifdef DEBUG_METHODS_ENABLED
	(p_instance->*p_method)(VariantCasterAndValidate<P>::cast(p_args, Is, r_error)...);
#else
	(p_instance->*p_method)(VariantCaster<P>::cast(*p_args[Is])...);
#endif
	(void)(p_args); //avoid warning
}

#ifdef PTRCALL_ENABLED

template <class T, class... P, size_t... Is>
void call_with_ptr_args_helper(T *p_instance, void (T::*p_method)(P...), const void **p_args, IndexSequence<Is...>) {
	(p_instance->*p_method)(PtrToArg<P>::convert(p_args[Is])...);
}

template <class T, class... P, size_t... Is>
void call_with_ptr_argsc_helper(T *p_instance, void (T::*p_method)(P...) const, const void **p_args, IndexSequence<Is...>) {
	(p_instance->*p_method)(PtrToArg<P>::convert(p_args[Is])...);
}

template <class T, class R, class... P, size_t... Is>
void call_with_ptr_args_ret_helper(T *p_instance, R (T::*p_method)(P...), const void **p_args, void *r_ret, IndexSequence<Is...>) {
	PtrToArg<R>::encode((p_instance->*p_method)(PtrToArg<P>::convert(p_args[Is])...), r_ret);
}

template <class T, class R, class... P, size_t... Is>
void call_with_ptr_args_retc_helper(T *p_instance, R (T::*p_method)(P...) const, const void **p_args, void *r_ret, IndexSequence<Is...>) {
	PtrToArg<R>::encode((p_instance->*p_method)(PtrToArg<P>::convert(p_args[Is])...), r_ret);
}

template <class T, class R, class... P, size_t... Is>
void call_with_ptr_args_static_retc_helper(T *p_instance, R (*p_method)(T *, P...), const void **p_args, void *r_ret, IndexSequence<Is...>) {
	PtrToArg<R>::encode(p_method(p_instance, PtrToArg<P>::convert(p_args[Is])...), r_ret);
}

#endif // PTRCALL_ENABLED

template <class T, class... P, size_t... Is>
void call_with_validated_variant_args_helper(T *p_instance, void (T::*p_method)(P...), const Variant **p_args, IndexSequence<Is...>) {
	(p_instance->*p_method)((VariantInternalAccessor<typename GetSimpleTypeT<P>::type_t>::get(p_args[Is]))...);
}

template <class T, class... P, size_t... Is>
void call_with_validated_variant_argsc_helper(T *p_instance, void (T::*p_method)(P...) const, const Variant **p_args, IndexSequence<Is...>) {
	(p_instance->*p_method)((VariantInternalAccessor<typename GetSimpleTypeT<P>::type_t>::get(p_args[Is]))...);
}

template <class T, class R, class... P, size_t... Is>
void call_with_validated_variant_args_ret_helper(T *p_instance, R (T::*p_method)(P...), const Variant **p_args, Variant *r_ret, IndexSequence<Is...>) {
	VariantInternalAccessor<typename GetSimpleTypeT<R>::type_t>::set(r_ret, (p_instance->*p_method)((VariantInternalAccessor<typename GetSimpleTypeT<P>::type_t>::get(p_args[Is]))...));
}

template <class T, class R, class... P, size_t... Is>
void call_with_validated_variant_args_retc_helper(T *p_instance, R (T::*p_method)(P...) const, const Variant **p_args, Variant *r_ret, IndexSequence<Is...>) {
	VariantInternalAccessor<typename GetSimpleTypeT<R>::type_t>::set(r_ret, (p_instance->*p_method)((VariantInternalAccessor<typename GetSimpleTypeT<P>::type_t>::get(p_args[Is]))...));
}

template <class T, class R, class... P, size_t... Is>
void call_with_validated_variant_args_static_retc_helper(T *p_instance, R (*p_method)(T *, P...), const Variant **p_args, Variant *r_ret, IndexSequence<Is...>) {
	VariantInternalAccessor<typename GetSimpleTypeT<R>::type_t>::set(r_ret, p_method(p_instance, (VariantInternalAccessor<typename GetSimpleTypeT<P>::type_t>::get(p_args[Is]))...));
}

template <class T, class... P>
void call_with_variant_args(T *p_instance, void (T::*p_method)(P...), const Variant **p_args, int p_argcount, Callable::CallError &r_error) {
#ifdef DEBUG_METHODS_ENABLED
	if ((size_t)p_argcount > sizeof...(P)) {
		r_error.error = Callable::CallError::CALL_ERROR_TOO_MANY_ARGUMENTS;
		r_error.argument = sizeof...(P);
		return;
	}

	if ((size_t)p_argcount < sizeof...(P)) {
		r_error.error = Callable::CallError::CALL_ERROR_TOO_FEW_ARGUMENTS;
		r_error.argument = sizeof...(P);
		return;
	}
#endif
	call_with_variant_args_helper<T, P...>(p_instance, p_method, p_args, r_error, BuildIndexSequence<sizeof...(P)>{});
}

template <class T, class... P>
void call_with_variant_args_dv(T *p_instance, void (T::*p_method)(P...), const Variant **p_args, int p_argcount, Callable::CallError &r_error, const Vector<Variant> &default_values) {
#ifdef DEBUG_ENABLED
	if ((size_t)p_argcount > sizeof...(P)) {
		r_error.error = Callable::CallError::CALL_ERROR_TOO_MANY_ARGUMENTS;
		r_error.argument = sizeof...(P);
		return;
	}
#endif

	int32_t missing = (int32_t)sizeof...(P) - (int32_t)p_argcount;

	int32_t dvs = default_values.size();
#ifdef DEBUG_ENABLED
	if (missing > dvs) {
		r_error.error = Callable::CallError::CALL_ERROR_TOO_FEW_ARGUMENTS;
		r_error.argument = sizeof...(P);
		return;
	}
#endif

	const Variant *args[sizeof...(P) == 0 ? 1 : sizeof...(P)]; //avoid zero sized array
	for (int32_t i = 0; i < (int32_t)sizeof...(P); i++) {
		if (i < p_argcount) {
			args[i] = p_args[i];
		} else {
			args[i] = &default_values[i - p_argcount + (dvs - missing)];
		}
	}

	call_with_variant_args_helper(p_instance, p_method, args, r_error, BuildIndexSequence<sizeof...(P)>{});
}

template <class T, class... P>
void call_with_variant_argsc(T *p_instance, void (T::*p_method)(P...) const, const Variant **p_args, int p_argcount, Callable::CallError &r_error) {
#ifdef DEBUG_METHODS_ENABLED
	if ((size_t)p_argcount > sizeof...(P)) {
		r_error.error = Callable::CallError::CALL_ERROR_TOO_MANY_ARGUMENTS;
		r_error.argument = sizeof...(P);
		return;
	}

	if ((size_t)p_argcount < sizeof...(P)) {
		r_error.error = Callable::CallError::CALL_ERROR_TOO_FEW_ARGUMENTS;
		r_error.argument = sizeof...(P);
		return;
	}
#endif
	call_with_variant_args_helper<T, P...>(p_instance, p_method, p_args, r_error, BuildIndexSequence<sizeof...(P)>{});
}

template <class T, class... P>
void call_with_variant_argsc_dv(T *p_instance, void (T::*p_method)(P...) const, const Variant **p_args, int p_argcount, Callable::CallError &r_error, const Vector<Variant> &default_values) {
#ifdef DEBUG_ENABLED
	if ((size_t)p_argcount > sizeof...(P)) {
		r_error.error = Callable::CallError::CALL_ERROR_TOO_MANY_ARGUMENTS;
		r_error.argument = sizeof...(P);
		return;
	}
#endif

	int32_t missing = (int32_t)sizeof...(P) - (int32_t)p_argcount;

	int32_t dvs = default_values.size();
#ifdef DEBUG_ENABLED
	if (missing > dvs) {
		r_error.error = Callable::CallError::CALL_ERROR_TOO_FEW_ARGUMENTS;
		r_error.argument = sizeof...(P);
		return;
	}
#endif

	const Variant *args[sizeof...(P) == 0 ? 1 : sizeof...(P)]; //avoid zero sized array
	for (int32_t i = 0; i < (int32_t)sizeof...(P); i++) {
		if (i < p_argcount) {
			args[i] = p_args[i];
		} else {
			args[i] = &default_values[i - p_argcount + (dvs - missing)];
		}
	}

	call_with_variant_argsc_helper(p_instance, p_method, args, r_error, BuildIndexSequence<sizeof...(P)>{});
}

template <class T, class R, class... P>
void call_with_variant_args_ret_dv(T *p_instance, R (T::*p_method)(P...), const Variant **p_args, int p_argcount, Variant &r_ret, Callable::CallError &r_error, const Vector<Variant> &default_values) {
#ifdef DEBUG_ENABLED
	if ((size_t)p_argcount > sizeof...(P)) {
		r_error.error = Callable::CallError::CALL_ERROR_TOO_MANY_ARGUMENTS;
		r_error.argument = sizeof...(P);
		return;
	}
#endif

	int32_t missing = (int32_t)sizeof...(P) - (int32_t)p_argcount;

	int32_t dvs = default_values.size();
#ifdef DEBUG_ENABLED
	if (missing > dvs) {
		r_error.error = Callable::CallError::CALL_ERROR_TOO_FEW_ARGUMENTS;
		r_error.argument = sizeof...(P);
		return;
	}
#endif

	const Variant *args[sizeof...(P) == 0 ? 1 : sizeof...(P)]; //avoid zero sized array
	for (int32_t i = 0; i < (int32_t)sizeof...(P); i++) {
		if (i < p_argcount) {
			args[i] = p_args[i];
		} else {
			args[i] = &default_values[i - p_argcount + (dvs - missing)];
		}
	}

	call_with_variant_args_ret_helper(p_instance, p_method, args, r_ret, r_error, BuildIndexSequence<sizeof...(P)>{});
}

template <class T, class R, class... P>
void call_with_variant_args_retc_dv(T *p_instance, R (T::*p_method)(P...) const, const Variant **p_args, int p_argcount, Variant &r_ret, Callable::CallError &r_error, const Vector<Variant> &default_values) {
#ifdef DEBUG_ENABLED
	if ((size_t)p_argcount > sizeof...(P)) {
		r_error.error = Callable::CallError::CALL_ERROR_TOO_MANY_ARGUMENTS;
		r_error.argument = sizeof...(P);
		return;
	}
#endif

	int32_t missing = (int32_t)sizeof...(P) - (int32_t)p_argcount;

	int32_t dvs = default_values.size();
#ifdef DEBUG_ENABLED
	if (missing > dvs) {
		r_error.error = Callable::CallError::CALL_ERROR_TOO_FEW_ARGUMENTS;
		r_error.argument = sizeof...(P);
		return;
	}
#endif

	const Variant *args[sizeof...(P) == 0 ? 1 : sizeof...(P)]; //avoid zero sized array
	for (int32_t i = 0; i < (int32_t)sizeof...(P); i++) {
		if (i < p_argcount) {
			args[i] = p_args[i];
		} else {
			args[i] = &default_values[i - p_argcount + (dvs - missing)];
		}
	}

	call_with_variant_args_retc_helper(p_instance, p_method, args, r_ret, r_error, BuildIndexSequence<sizeof...(P)>{});
}

#ifdef PTRCALL_ENABLED

template <class T, class... P>
void call_with_ptr_args(T *p_instance, void (T::*p_method)(P...), const void **p_args) {
	call_with_ptr_args_helper<T, P...>(p_instance, p_method, p_args, BuildIndexSequence<sizeof...(P)>{});
}

template <class T, class... P>
void call_with_ptr_argsc(T *p_instance, void (T::*p_method)(P...) const, const void **p_args) {
	call_with_ptr_argsc_helper<T, P...>(p_instance, p_method, p_args, BuildIndexSequence<sizeof...(P)>{});
}

template <class T, class R, class... P>
void call_with_ptr_args_ret(T *p_instance, R (T::*p_method)(P...), const void **p_args, void *r_ret) {
	call_with_ptr_args_ret_helper<T, R, P...>(p_instance, p_method, p_args, r_ret, BuildIndexSequence<sizeof...(P)>{});
}

template <class T, class R, class... P>
void call_with_ptr_args_retc(T *p_instance, R (T::*p_method)(P...) const, const void **p_args, void *r_ret) {
	call_with_ptr_args_retc_helper<T, R, P...>(p_instance, p_method, p_args, r_ret, BuildIndexSequence<sizeof...(P)>{});
}

template <class T, class R, class... P>
void call_with_ptr_args_static_retc(T *p_instance, R (*p_method)(T *, P...), const void **p_args, void *r_ret) {
	call_with_ptr_args_static_retc_helper<T, R, P...>(p_instance, p_method, p_args, r_ret, BuildIndexSequence<sizeof...(P)>{});
}

#endif // PTRCALL_ENABLED

template <class T, class... P>
void call_with_validated_variant_args(Variant *base, void (T::*p_method)(P...), const Variant **p_args) {
	call_with_validated_variant_args_helper<T, P...>(VariantGetInternalPtr<T>::get_ptr(base), p_method, p_args, BuildIndexSequence<sizeof...(P)>{});
}

template <class T, class R, class... P>
void call_with_validated_variant_args_ret(Variant *base, R (T::*p_method)(P...), const Variant **p_args, Variant *r_ret) {
	call_with_validated_variant_args_ret_helper<T, R, P...>(VariantGetInternalPtr<T>::get_ptr(base), p_method, p_args, r_ret, BuildIndexSequence<sizeof...(P)>{});
}

template <class T, class R, class... P>
void call_with_validated_variant_args_retc(Variant *base, R (T::*p_method)(P...) const, const Variant **p_args, Variant *r_ret) {
	call_with_validated_variant_args_retc_helper<T, R, P...>(VariantGetInternalPtr<T>::get_ptr(base), p_method, p_args, r_ret, BuildIndexSequence<sizeof...(P)>{});
}

template <class T, class R, class... P>
void call_with_validated_variant_args_static_retc(Variant *base, R (*p_method)(T *, P...), const Variant **p_args, Variant *r_ret) {
	call_with_validated_variant_args_static_retc_helper<T, R, P...>(VariantGetInternalPtr<T>::get_ptr(base), p_method, p_args, r_ret, BuildIndexSequence<sizeof...(P)>{});
}

// GCC raises "parameter 'p_args' set but not used" when P = {},
// it's not clever enough to treat other P values as making this branch valid.
#if defined(DEBUG_METHODS_ENABLED) && defined(__GNUC__) && !defined(__clang__)
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wunused-but-set-parameter"
#endif

#ifdef DEBUG_METHODS_ENABLED

template <class Q>
void call_get_argument_type_helper(int p_arg, int &index, Variant::Type &type) {
	if (p_arg == index) {
		type = GetTypeInfo<Q>::VARIANT_TYPE;
	}
	index++;
}

template <class... P>
Variant::Type call_get_argument_type(int p_arg) {
	Variant::Type type = Variant::NIL;
	int index = 0;
	// I think rocket science is simpler than modern C++.
	using expand_type = int[];
	expand_type a{ 0, (call_get_argument_type_helper<P>(p_arg, index, type), 0)... };
	(void)a; // Suppress (valid, but unavoidable) -Wunused-variable warning.
	(void)index; // Suppress GCC warning.
	return type;
}

template <class Q>
void call_get_argument_type_info_helper(int p_arg, int &index, PropertyInfo &info) {
	if (p_arg == index) {
		info = GetTypeInfo<Q>::get_class_info();
	}
	index++;
}

template <class... P>
void call_get_argument_type_info(int p_arg, PropertyInfo &info) {
	int index = 0;
	// I think rocket science is simpler than modern C++.
	using expand_type = int[];
	expand_type a{ 0, (call_get_argument_type_info_helper<P>(p_arg, index, info), 0)... };
	(void)a; // Suppress (valid, but unavoidable) -Wunused-variable warning.
	(void)index; // Suppress GCC warning.
}

template <class Q>
void call_get_argument_metadata_helper(int p_arg, int &index, GodotTypeInfo::Metadata &md) {
	if (p_arg == index) {
		md = GetTypeInfo<Q>::METADATA;
	}
	index++;
}

template <class... P>
GodotTypeInfo::Metadata call_get_argument_metadata(int p_arg) {
	GodotTypeInfo::Metadata md = GodotTypeInfo::METADATA_NONE;

	int index = 0;
	// I think rocket science is simpler than modern C++.
	using expand_type = int[];
	expand_type a{ 0, (call_get_argument_metadata_helper<P>(p_arg, index, md), 0)... };
	(void)a; // Suppress (valid, but unavoidable) -Wunused-variable warning.
	(void)index;
	return md;
}

#else

template <class... P>
Variant::Type call_get_argument_type(int p_arg) {
	return Variant::NIL;
}

#endif // DEBUG_METHODS_ENABLED

//////////////////////

template <class T, class R, class... P, size_t... Is>
void call_with_variant_args_ret_helper(T *p_instance, R (T::*p_method)(P...), const Variant **p_args, Variant &r_ret, Callable::CallError &r_error, IndexSequence<Is...>) {
	r_error.error = Callable::CallError::CALL_OK;

#ifdef DEBUG_METHODS_ENABLED
	r_ret = (p_instance->*p_method)(VariantCasterAndValidate<P>::cast(p_args, Is, r_error)...);
#else
	r_ret = (p_instance->*p_method)(VariantCaster<P>::cast(*p_args[Is])...);
#endif
}

template <class T, class R, class... P>
void call_with_variant_args_ret(T *p_instance, R (T::*p_method)(P...), const Variant **p_args, int p_argcount, Variant &r_ret, Callable::CallError &r_error) {
#ifdef DEBUG_METHODS_ENABLED
	if ((size_t)p_argcount > sizeof...(P)) {
		r_error.error = Callable::CallError::CALL_ERROR_TOO_MANY_ARGUMENTS;
		r_error.argument = sizeof...(P);
		return;
	}

	if ((size_t)p_argcount < sizeof...(P)) {
		r_error.error = Callable::CallError::CALL_ERROR_TOO_FEW_ARGUMENTS;
		r_error.argument = sizeof...(P);
		return;
	}
#endif
	call_with_variant_args_ret_helper<T, R, P...>(p_instance, p_method, p_args, r_ret, r_error, BuildIndexSequence<sizeof...(P)>{});
}

template <class T, class R, class... P, size_t... Is>
void call_with_variant_args_retc_helper(T *p_instance, R (T::*p_method)(P...) const, const Variant **p_args, Variant &r_ret, Callable::CallError &r_error, IndexSequence<Is...>) {
	r_error.error = Callable::CallError::CALL_OK;

#ifdef DEBUG_METHODS_ENABLED
	r_ret = (p_instance->*p_method)(VariantCasterAndValidate<P>::cast(p_args, Is, r_error)...);
#else
	r_ret = (p_instance->*p_method)(VariantCaster<P>::cast(*p_args[Is])...);
#endif
	(void)p_args;
}

template <class T, class R, class... P>
void call_with_variant_args_retc(T *p_instance, R (T::*p_method)(P...) const, const Variant **p_args, int p_argcount, Variant &r_ret, Callable::CallError &r_error) {
#ifdef DEBUG_METHODS_ENABLED
	if ((size_t)p_argcount > sizeof...(P)) {
		r_error.error = Callable::CallError::CALL_ERROR_TOO_MANY_ARGUMENTS;
		r_error.argument = sizeof...(P);
		return;
	}

	if ((size_t)p_argcount < sizeof...(P)) {
		r_error.error = Callable::CallError::CALL_ERROR_TOO_FEW_ARGUMENTS;
		r_error.argument = sizeof...(P);
		return;
	}
#endif
	call_with_variant_args_retc_helper<T, R, P...>(p_instance, p_method, p_args, r_ret, r_error, BuildIndexSequence<sizeof...(P)>{});
}

template <class T, class R, class... P, size_t... Is>
void call_with_variant_args_retc_static_helper(T *p_instance, R (*p_method)(T *, P...), const Variant **p_args, Variant &r_ret, Callable::CallError &r_error, IndexSequence<Is...>) {
	r_error.error = Callable::CallError::CALL_OK;

#ifdef DEBUG_METHODS_ENABLED
	r_ret = (p_method)(p_instance, VariantCasterAndValidate<P>::cast(p_args, Is, r_error)...);
#else
	r_ret = (p_method)(p_instance, VariantCaster<P>::cast(*p_args[Is])...);
#endif

	(void)p_args;
}

template <class T, class R, class... P>
void call_with_variant_args_retc_static_helper_dv(T *p_instance, R (*p_method)(T *, P...), const Variant **p_args, int p_argcount, Variant &r_ret, const Vector<Variant> &default_values, Callable::CallError &r_error) {
#ifdef DEBUG_ENABLED
	if ((size_t)p_argcount > sizeof...(P)) {
		r_error.error = Callable::CallError::CALL_ERROR_TOO_MANY_ARGUMENTS;
		r_error.argument = sizeof...(P);
		return;
	}
#endif

	int32_t missing = (int32_t)sizeof...(P) - (int32_t)p_argcount;

	int32_t dvs = default_values.size();
#ifdef DEBUG_ENABLED
	if (missing > dvs) {
		r_error.error = Callable::CallError::CALL_ERROR_TOO_FEW_ARGUMENTS;
		r_error.argument = sizeof...(P);
		return;
	}
#endif

	const Variant *args[sizeof...(P) == 0 ? 1 : sizeof...(P)]; //avoid zero sized array
	for (int32_t i = 0; i < (int32_t)sizeof...(P); i++) {
		if (i < p_argcount) {
			args[i] = p_args[i];
		} else {
			args[i] = &default_values[i - p_argcount + (dvs - missing)];
		}
	}

	call_with_variant_args_retc_static_helper(p_instance, p_method, args, r_ret, r_error, BuildIndexSequence<sizeof...(P)>{});
}

#if defined(DEBUG_METHODS_ENABLED) && defined(__GNUC__) && !defined(__clang__)
#pragma GCC diagnostic pop
#endif

#endif // BINDER_COMMON_H