Files
meta.hpp/develop/untests/meta_issues/github_discussion_88.cpp
2024-06-18 00:40:33 +07:00

75 lines
3.0 KiB
C++

/*******************************************************************************
* This file is part of the "https://github.com/blackmatov/meta.hpp"
* For conditions of distribution and use, see copyright notice in LICENSE.md
* Copyright (C) 2021-2024, by Matvey Cherevko (blackmatov@gmail.com)
******************************************************************************/
#include <meta.hpp/meta_all.hpp>
#include <doctest/doctest.h>
namespace
{
struct component {
component() = default;
component(const component&) = default;
virtual ~component() = default;
META_HPP_ENABLE_POLY_INFO()
};
struct position_component : component {
META_HPP_ENABLE_POLY_INFO(component)
public:
explicit position_component(int nx, int ny) : x{nx}, y{ny} {}
int x{};
int y{};
};
}
TEST_CASE("meta/meta_discussion/88") {
namespace meta = meta_hpp;
meta::class_<position_component>()
.member_("x", &position_component::x, meta::member_policy::as_pointer)
.member_("y", &position_component::y, meta::member_policy::as_pointer);
position_component position{21, 42};
std::vector<component*> components{&position};
for (component* c : components) {
// meta_poly_ptr returns a pointer of the most derived type (position_component* in this case)
meta::uvalue derived_instance_ptr = c->meta_poly_ptr();
meta::any_type derived_instance_ptr_type = derived_instance_ptr.get_type();
CHECK(derived_instance_ptr_type == meta::resolve_type<position_component*>());
// to get all members of the component we should extract a class type from the pointer (position_component)
meta::class_type derived_instance_type = derived_instance_ptr_type.as_pointer().get_data_type().as_class();
CHECK(derived_instance_type == meta::resolve_type<position_component>());
// for each member we can show our debug inspector (imgui input for example)
for (const meta::member& m : derived_instance_type.get_members()) {
// we registered members as pointers (member_policy::as_pointer), so the type of the member is a pointer
CHECK(m.get_type() == meta::resolve_type<int position_component::*>());
CHECK(m.get_type().get_value_type() == meta::resolve_type<int>());
// Note:
// We can register members without any policy then member::get will return copy of this member value,
// and to change this member we will have to call member::set function.
// But in this case we will change values in-place by a pointer
meta::uvalue value = m.get(derived_instance_ptr);
CHECK(value.get_type() == meta::resolve_type<int*>());
int* raw_value = value.as<int*>();
// here we can show the value on the screen or change it
CHECK((*raw_value == 21 || *raw_value == 42));
*raw_value = 84;
}
CHECK(position.x == 84);
CHECK(position.y == 84);
}
}