godot/core/callable_method_pointer.h

/*************************************************************************/
/*  callable_method_pointer.h                                            */
/*************************************************************************/
/*                       This file is part of:                           */
/*                           GODOT ENGINE                                */
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/* Copyright (c) 2007-2020 Juan Linietsky, Ariel Manzur.                 */
/* Copyright (c) 2014-2020 Godot Engine contributors (cf. AUTHORS.md).   */
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/* "Software"), to deal in the Software without restriction, including   */
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/* included in all copies or substantial portions of the Software.       */
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#ifndef CALLABLE_METHOD_POINTER_H
#define CALLABLE_METHOD_POINTER_H

#include "core/callable.h"
#include "core/hashfuncs.h"
#include "core/object.h"
#include "core/os/copymem.h"
#include "core/simple_type.h"
#include "core/variant_internal.h"

class CallableCustomMethodPointerBase : public CallableCustom {
	uint32_t *comp_ptr;
	uint32_t comp_size;
	uint32_t h;
#ifdef DEBUG_METHODS_ENABLED
	const char *text = "";
#endif
	static bool compare_equal(const CallableCustom *p_a, const CallableCustom *p_b);
	static bool compare_less(const CallableCustom *p_a, const CallableCustom *p_b);

protected:
	void _setup(uint32_t *p_base_ptr, uint32_t p_ptr_size);

public:
#ifdef DEBUG_METHODS_ENABLED
	void set_text(const char *p_text) {
		text = p_text;
	}
	virtual String get_as_text() const {
		return text;
	}
#else
	virtual String get_as_text() const {
		return String();
	}
#endif
	virtual CompareEqualFunc get_compare_equal_func() const;
	virtual CompareLessFunc get_compare_less_func() const;

	virtual uint32_t hash() const;
};

#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)) {
			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)) {
			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)) {
			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

// GCC raises "parameter 'p_args' set but not used" here, probably using a
// template version that does not have arguments and thus sees it unused, but
// obviously the template can be used for functions with and without them, and
// the optimizer will get rid of it anyway.
#if defined(DEBUG_METHODS_ENABLED) && defined(__GNUC__) && !defined(__clang__)
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wunused-but-set-parameter"
#endif

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
}

#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 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 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)>{});
}

#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 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)>{});
}

#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++;
}

// GCC's warnings checker really doesn't like variadic voodoo.
// It sees `index` unused below in some branches, so it raises a warning.
#if defined(__GNUC__) && !defined(__clang__)
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wunused-but-set-variable"
#endif

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.
	return type;
}

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

#else

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

#endif // DEBUG_METHODS_ENABLED

template <class T, class... P>
class CallableCustomMethodPointer : public CallableCustomMethodPointerBase {
	struct Data {
		T *instance;
#ifdef DEBUG_ENABLED
		uint64_t object_id;
#endif
		void (T::*method)(P...);
	} data;

public:
	virtual ObjectID get_object() const {
#ifdef DEBUG_ENABLED
		if (ObjectDB::get_instance(ObjectID(data.object_id)) == nullptr) {
			return ObjectID();
		}
#endif
		return data.instance->get_instance_id();
	}

	virtual void call(const Variant **p_arguments, int p_argcount, Variant &r_return_value, Callable::CallError &r_call_error) const {
#ifdef DEBUG_ENABLED
		ERR_FAIL_COND_MSG(ObjectDB::get_instance(ObjectID(data.object_id)) == nullptr, "Invalid Object id '" + uitos(data.object_id) + "', can't call method.");
#endif
		call_with_variant_args(data.instance, data.method, p_arguments, p_argcount, r_call_error);
	}

	CallableCustomMethodPointer(T *p_instance, void (T::*p_method)(P...)) {
		zeromem(&data, sizeof(Data)); // Clear beforehand, may have padding bytes.
		data.instance = p_instance;
#ifdef DEBUG_ENABLED
		data.object_id = p_instance->get_instance_id();
#endif
		data.method = p_method;
		_setup((uint32_t *)&data, sizeof(Data));
	}
};

template <class T, class... P>
Callable create_custom_callable_function_pointer(T *p_instance,
#ifdef DEBUG_METHODS_ENABLED
		const char *p_func_text,
#endif
		void (T::*p_method)(P...)) {

	typedef CallableCustomMethodPointer<T, P...> CCMP; // Messes with memnew otherwise.
	CCMP *ccmp = memnew(CCMP(p_instance, p_method));
#ifdef DEBUG_METHODS_ENABLED
	ccmp->set_text(p_func_text + 1); // Try to get rid of the ampersand.
#endif
	return Callable(ccmp);
}

// VERSION WITH RETURN

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>
class CallableCustomMethodPointerRet : public CallableCustomMethodPointerBase {
	struct Data {
		T *instance;
#ifdef DEBUG_ENABLED
		uint64_t object_id;
#endif
		R(T::*method)
		(P...);
	} data;

public:
	virtual ObjectID get_object() const {
#ifdef DEBUG_ENABLED
		if (ObjectDB::get_instance(ObjectID(data.object_id)) == nullptr) {
			return ObjectID();
		}
#endif
		return data.instance->get_instance_id();
	}

	virtual void call(const Variant **p_arguments, int p_argcount, Variant &r_return_value, Callable::CallError &r_call_error) const {
#ifdef DEBUG_ENABLED
		ERR_FAIL_COND_MSG(ObjectDB::get_instance(ObjectID(data.object_id)) == nullptr, "Invalid Object id '" + uitos(data.object_id) + "', can't call method.");
#endif
		call_with_variant_args_ret(data.instance, data.method, p_arguments, p_argcount, r_return_value, r_call_error);
	}

	CallableCustomMethodPointerRet(T *p_instance, R (T::*p_method)(P...)) {
		zeromem(&data, sizeof(Data)); // Clear beforehand, may have padding bytes.
		data.instance = p_instance;
#ifdef DEBUG_ENABLED
		data.object_id = p_instance->get_instance_id();
#endif
		data.method = p_method;
		_setup((uint32_t *)&data, sizeof(Data));
	}
};

template <class T, class R, class... P>
Callable create_custom_callable_function_pointer(T *p_instance,
#ifdef DEBUG_METHODS_ENABLED
		const char *p_func_text,
#endif
		R (T::*p_method)(P...)) {

	typedef CallableCustomMethodPointerRet<T, R, P...> CCMP; // Messes with memnew otherwise.
	CCMP *ccmp = memnew(CCMP(p_instance, p_method));
#ifdef DEBUG_METHODS_ENABLED
	ccmp->set_text(p_func_text + 1); // Try to get rid of the ampersand.
#endif
	return Callable(ccmp);
}

// CONST VERSION WITH RETURN

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
}

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>
class CallableCustomMethodPointerRetC : public CallableCustomMethodPointerBase {
	struct Data {
		T *instance;
#ifdef DEBUG_ENABLED
		uint64_t object_id;
#endif
		R(T::*method)
		(P...) const;
	} data;

public:
	virtual ObjectID get_object() const {
#ifdef DEBUG_ENABLED
		if (ObjectDB::get_instance(ObjectID(data.object_id)) == nullptr) {
			return ObjectID();
		}
#endif
		return data.instance->get_instance_id();
	}

	virtual void call(const Variant **p_arguments, int p_argcount, Variant &r_return_value, Callable::CallError &r_call_error) const {
#ifdef DEBUG_ENABLED
		ERR_FAIL_COND_MSG(ObjectDB::get_instance(ObjectID(data.object_id)) == nullptr, "Invalid Object id '" + uitos(data.object_id) + "', can't call method.");
#endif
		call_with_variant_args_retc(data.instance, data.method, p_arguments, p_argcount, r_return_value, r_call_error);
	}

	CallableCustomMethodPointerRetC(T *p_instance, R (T::*p_method)(P...) const) {
		zeromem(&data, sizeof(Data)); // Clear beforehand, may have padding bytes.
		data.instance = p_instance;
#ifdef DEBUG_ENABLED
		data.object_id = p_instance->get_instance_id();
#endif
		data.method = p_method;
		_setup((uint32_t *)&data, sizeof(Data));
	}
};

template <class T, class R, class... P>
Callable create_custom_callable_function_pointer(T *p_instance,
#ifdef DEBUG_METHODS_ENABLED
		const char *p_func_text,
#endif
		R (T::*p_method)(P...) const) {

	typedef CallableCustomMethodPointerRetC<T, R, P...> CCMP; // Messes with memnew otherwise.
	CCMP *ccmp = memnew(CCMP(p_instance, p_method));
#ifdef DEBUG_METHODS_ENABLED
	ccmp->set_text(p_func_text + 1); // Try to get rid of the ampersand.
#endif
	return Callable(ccmp);
}

#ifdef DEBUG_METHODS_ENABLED
#define callable_mp(I, M) create_custom_callable_function_pointer(I, #M, M)
#else
#define callable_mp(I, M) create_custom_callable_function_pointer(I, M)
#endif

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
}

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

#endif // CALLABLE_METHOD_POINTER_H