draconisplusplus/include/rfl/parsing/Parser_pair.hpp

#ifndef RFL_PARSING_PARSER_PAIR_HPP_
#define RFL_PARSING_PARSER_PAIR_HPP_

#include <map>
#include <type_traits>
#include <utility>

#include "../Ref.hpp"
#include "../Result.hpp"
#include "../always_false.hpp"
#include "Parser_base.hpp"
#include "schema/Type.hpp"

namespace rfl {
  namespace parsing {

    template <
        class R,
        class W,
        class FirstType,
        class SecondType,
        class ProcessorsType>
      requires AreReaderAndWriter<R, W, std::pair<FirstType, SecondType>>
    struct Parser<R, W, std::pair<FirstType, SecondType>, ProcessorsType> {
      using InputVarType  = typename R::InputVarType;
      using OutputVarType = typename W::OutputVarType;

      /// Expresses the variables as type T.
      static Result<std::pair<FirstType, SecondType>>
      read(const R& _r, const InputVarType& _var) noexcept {
        const auto to_pair = [&](auto&& _t) {
          return std::make_pair(
              std::move(std::get<0>(_t)), std::move(std::get<1>(_t))
          );
        };
        return Parser<R, W, std::tuple<FirstType, SecondType>, ProcessorsType>::
            read(_r, _var)
                .transform(to_pair);
      }

      template <class P>
      static void write(
          const W&                                _w,
          const std::pair<FirstType, SecondType>& _p,
          const P&                                _parent
      ) noexcept {
        const auto tup = std::make_tuple(&_p.first, &_p.second);
        Parser<
            R,
            W,
            std::tuple<const FirstType*, const SecondType*>,
            ProcessorsType>::write(_w, tup, _parent);
      }

      static schema::Type to_schema(
          std::map<std::string, schema::Type>* _definitions
      ) {
        return Parser<R, W, std::tuple<FirstType, SecondType>, ProcessorsType>::
            to_schema(_definitions);
      }
    };

  } // namespace parsing
} // namespace rfl

#endif