Serializing all enums as strings

[topiolli]

The documentation suggests to use simple_enum for automatic enum-to-string conversions. Unfortunately simple_enum doesn't seem to support Glaze 6. I was however able to automatically convert all enums to strings using magic_enum. I believe simple_enum has a similar facility and could be used as well. Here's the code. Short enough to be included in documentation?

#include <glaze/core/common.hpp>
#include <glaze/core/meta.hpp>
#include <magic_enum/magic_enum.hpp>
#include <type_traits>

namespace glz {
template <typename T>
concept enumerated = std::is_enum_v<T>;

/**
 * Makes Glaze use enum value names instead of integral indices.
 */
template <enumerated T>
struct meta<T> {
  static constexpr auto value = []<std::size_t... Is>(auto values, std::index_sequence<Is...>) {
    return enumerate(values[Is]...);
  }(magic_enum::enum_values<T>(), std::make_index_sequence<magic_enum::enum_count<T>()>());
};

}  // namespace glz

[stephenberry]

Thanks for sharing this, that is an elegant approach. I'll add something to the documentation about this.

Glaze also support separate keys and value arrays, which should compile faster:

template <class T>                                                         
   requires std::is_enum_v<T>                                                 
struct meta<T>                                                                
{                                                                             
   static constexpr auto keys = magic_enum::enum_names<T>();                  
   static constexpr auto value = magic_enum::enum_values<T>();                
};

[topiolli]

That's even simpler, thanks!

My compiler (gcc 14) complains about different requires clauses for glz::meta if I don't make "enumerated" a concept and place it into the template parameter list. I don't know if it is the compiler or yet another C++ insanity, but that's how I got it working.

[stephenberry]

You're welcome, and that sounds like a compiler bug, but your enumerated concept approach is clean and good.