metamethods.hpp

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#pragma once
#include <meta>
 
#include <welder/bind_traits.hpp>          // is_unary_operator
#include <welder/rods/lua/metamethods.hpp> // shared operator -> Lua __name map
 
#include <sol/sol.hpp>

 
namespace welder::inline v0::rods::sol2 {

struct metamethod {
    ::sol::meta_function fn; 
    const char* name;        
};

consteval metamethod operator_mm(std::meta::info f) {
    using std::meta::operators;
    using mf = ::sol::meta_function;
    const char* name{::welder::rods::lua::lua_metamethod_name(f)};
    if (name == nullptr)
        return {mf::index, nullptr};
    const bool unary{::welder::detail::is_unary_operator(f)};
    switch (std::meta::operator_of(f)) {
        case operators::op_plus:          return {mf::addition, name};
        case operators::op_minus:
            return unary ? metamethod{mf::unary_minus, name}
                         : metamethod{mf::subtraction, name};
        case operators::op_star:          return {mf::multiplication, name};
        case operators::op_slash:         return {mf::division, name};
        case operators::op_percent:       return {mf::modulus, name};
        case operators::op_equals_equals: return {mf::equal_to, name};
        case operators::op_less:          return {mf::less_than, name};
        case operators::op_less_equals:   return {mf::less_than_or_equal_to, name};
        case operators::op_parentheses:   return {mf::call, name};
        case operators::op_square_brackets: return {mf::index, name};
#if defined(LUA_VERSION_NUM) && LUA_VERSION_NUM >= 503
        case operators::op_caret:         return {mf::bitwise_xor, name};
        case operators::op_tilde:         return {mf::bitwise_not, name};
        case operators::op_ampersand:     return {mf::bitwise_and, name};
        case operators::op_pipe:          return {mf::bitwise_or, name};
        case operators::op_less_less:     return {mf::bitwise_left_shift, name};
        case operators::op_greater_greater: return {mf::bitwise_right_shift, name};
#endif
        default: return {mf::index, nullptr};
    }
}
 
} // namespace welder::rods::sol2