daw_json_data_contract.h

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// Copyright (c) Darrell Wright
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE or copy at http://www.boost.org/LICENSE_1_0.txt)
//
// Official repository: https://github.com/beached/daw_json_link
//
 
#pragma once
 
#include "daw/json/impl/version.h"
 
#include "daw/json/impl/daw_json_req_helper.h"
 
#include <daw/daw_cpp20_concept.h>
 
#include <type_traits>
 
namespace daw::json {
  inline namespace DAW_JSON_VER {
    template<typename>
    struct missing_json_data_contract_for_or_unknown_type;
 
    template<typename T>
    inline constexpr bool is_missing_data_contract_or_unknown_type_v = false;
 
    template<>
    inline constexpr bool is_missing_data_contract_or_unknown_type_v<void> =
      true;
 
    template<typename T>
    inline constexpr bool is_missing_data_contract_or_unknown_type_v<
      missing_json_data_contract_for_or_unknown_type<T>> = true;
 
    template<typename T, typename = void>
    struct json_data_contract {
      using type = missing_json_data_contract_for_or_unknown_type<T>;
    };
 
    template<typename T>
    using json_data_contract_trait_t = typename json_data_contract<T>::type;
 
    namespace json_details {
      template<typename T>
      DAW_CPP20_CONCEPT has_json_data_contract_trait_v =
        not std::is_same_v<missing_json_data_contract_for_or_unknown_type<T>,
                           json_data_contract_trait_t<T>>;
 
      DAW_JSON_MAKE_REQ_TRAIT(
        has_json_to_json_data_v,
        json_data_contract<T>::to_json_data( std::declval<T &>( ) ) );
 
      DAW_JSON_MAKE_REQ_TYPE_ALIAS_TRAIT(
        is_submember_tagged_variant_v,
        json_data_contract<T>::type::i_am_a_submember_tagged_variant );
    } // namespace json_details
  } // namespace DAW_JSON_VER
} // namespace daw::json