config_struct_details.h

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#pragma once
 
#include <boost/hana/for_each.hpp>
 
#include "../trace.h"
#include "common.h"
 
//fwd
namespace armarx::meta::cfg
{
    template <class CL, class MT, MT CL::*ptr>
    struct element_default;
}
 
//possible details
namespace armarx::meta::cfg
{
    template <class CL, class MT, MT CL::*ptr>
    using element_widget = undefined_t;
 
    template <class T>
    using config_layout = undefined_t;
 
    template <class CL, class = void>
    struct struct_default : std::false_type
    {
        static const CL&
        get()
        {
            static const CL cl;
            return cl;
        }
 
        static void
        set(CL& cl)
        {
            cl = get();
        }
    };
 
    template <class CL>
    struct struct_default<CL, std::enable_if_t<simox::meta::has_hana_accessor_v<CL>>> :
        std::false_type
    {
    private:
        template <class VarName, class MT, MT CL::*ptr>
        static void
        DoSetElement(
            const boost::hana::pair<VarName,
                                    boost::hana::struct_detail::member_ptr<MT CL::*, ptr>>&,
            CL& val)
        {
            if constexpr (element_default<CL, MT, ptr>::value)
            {
                element_default<CL, MT, ptr>::set(val);
            }
        }
 
    public:
        static void
        set(CL& cl)
        {
            static constexpr auto accessors = boost::hana::accessors<CL>();
            boost::hana::for_each(accessors,
                                  [&](auto& e)
                                  {
                                      ARMARX_TRACE_LITE;
                                      DoSetElement(e, cl);
                                  });
        }
 
        static const CL&
        get()
        {
            static const CL cl;
            set(cl);
            return cl;
        }
    };
} // namespace armarx::meta::cfg