basic_facade_builder::add_reflectionbasic_facade_builder::add_direct_reflectionbasic_facade_builder::add_indirect_reflectiontemplate <class R>
using add_reflection = add_indirect_reflection<R>;
template <class R>
using add_indirect_reflection = basic_facade_builder</* see below */>;
template <class R>
using add_direct_reflection = basic_facade_builder</* see below */>;
The alias templates add_reflection, add_indirect_reflection and add_direct_reflection of basic_facade_builder<Cs, Rs, C> add reflection types to the template parameters. Specifically,
add_reflection is equivalent to add_indirect_reflection.add_indirect_reflection merges an implementation-defined reflection type Refl into Rs, where:
Refl::is_direct is false.typename Refl::reflector_type is R.typename Refl::template accessor<F> is typename R::template accessor<F, false, R> if applicable.add_direct_reflection merges an implementation-defined reflection type Refl into Rs, where:
Refl::is_direct is true.typename Refl::reflector_type is R.typename Refl::template accessor<F> is typename R::template accessor<F, true, R> if applicable.When Rs already contains Refl, the template parameters shall not change.
Adding duplicate reflection types is well-defined, whether done directly via add_reflection, add_indirect_reflection, add_direct_reflection, or indirectly via add_facade. This process does not affect the behavior of build at either compile-time or runtime.
#include <array>
#include <iostream>
#include "proxy.h"
struct LayoutReflector {
public:
template <class T>
constexpr explicit LayoutReflector(std::in_place_type_t<T>)
: Size(sizeof(T)), Align(alignof(T)) {}
template <class F, bool IsDirect, class R>
struct accessor {
friend std::size_t SizeOf(const std::conditional_t<IsDirect, pro::proxy<F>,
pro::proxy_indirect_accessor<F>>& self) noexcept {
const LayoutReflector& refl = pro::proxy_reflect<IsDirect, R>(pro::access_proxy<F>(self));
return refl.Size;
}
friend std::size_t AlignOf(const std::conditional_t<IsDirect, pro::proxy<F>,
pro::proxy_indirect_accessor<F>>& self) noexcept {
const LayoutReflector& refl = pro::proxy_reflect<IsDirect, R>(pro::access_proxy<F>(self));
return refl.Align;
}
};
std::size_t Size, Align;
};
struct LayoutAware : pro::facade_builder
::add_direct_reflection<LayoutReflector>
::add_indirect_reflection<LayoutReflector>
::build {};
int main() {
int a = 123;
pro::proxy<LayoutAware> p = &a;
std::cout << SizeOf(p) << "\n"; // Prints sizeof(raw pointer)
std::cout << AlignOf(p) << "\n"; // Prints alignof(raw pointer)
std::cout << SizeOf(*p) << "\n"; // Prints sizeof(int)
std::cout << AlignOf(*p) << "\n"; // Prints alignof(int)
p = pro::make_proxy<LayoutAware>(123); // SBO enabled
std::cout << SizeOf(p) << "\n"; // Prints sizeof(int)
std::cout << AlignOf(p) << "\n"; // Prints alignof(int)
std::cout << SizeOf(*p) << "\n"; // Prints sizeof(int)
std::cout << AlignOf(*p) << "\n"; // Prints alignof(int)
p = pro::make_proxy<LayoutAware, std::array<char, 100>>(); // SBO disabled
std::cout << SizeOf(p) << "\n"; // Prints sizeof(raw pointer)
std::cout << AlignOf(p) << "\n"; // Prints alignof(raw pointer)
std::cout << SizeOf(*p) << "\n"; // Prints "100"
std::cout << AlignOf(*p) << "\n"; // Prints "1"
}