draconisplusplus/include/rfl/parsing/Parser_result.hpp
2024-06-08 15:53:06 -04:00

80 lines
2.3 KiB
C++

#ifndef RFL_PARSING_PARSER_RESULT_HPP_
#define RFL_PARSING_PARSER_RESULT_HPP_
#include <map>
#include <type_traits>
#include "../Result.hpp"
#include "../always_false.hpp"
#include "../internal/StringLiteral.hpp"
#include "Parser_base.hpp"
#include "schema/Type.hpp"
namespace rfl {
namespace parsing {
template <class R, class W, class T, class ProcessorsType>
requires AreReaderAndWriter<R, W, Result<T>>
struct Parser<R, W, Result<T>, ProcessorsType> {
using InputVarType = typename R::InputVarType;
using OutputVarType = typename W::OutputVarType;
using ErrorType = NamedTuple<Field<"error", std::string>>;
using VariantType = std::variant<std::remove_cvref_t<T>, ErrorType>;
static Result<Result<T>>
read(const R& _r, const InputVarType& _var) noexcept {
const auto handle = [](auto&& _t) -> Result<T> {
using Type = std::remove_cvref_t<decltype(_t)>;
if constexpr (std::is_same<Type, ErrorType>()) {
return Error(_t.template get<"error">());
} else {
return std::forward<std::remove_cvref_t<T>>(_t);
}
};
const auto to_res = [&](VariantType&& _v) -> Result<T> {
return std::visit(handle, std::forward<VariantType>(_v));
};
return Result<Result<T>>(
Parser<R, W, VariantType, ProcessorsType>::read(_r, _var).transform(
to_res
)
);
}
template <class P>
static void
write(const W& _w, const Result<T>& _r, const P& _parent) noexcept {
const auto write_t = [&](const auto& _t) -> Nothing {
Parser<R, W, std::remove_cvref_t<T>, ProcessorsType>::write(
_w, _t, _parent
);
return Nothing {};
};
const auto write_err = [&](const auto& _err) -> Nothing {
Parser<R, W, ErrorType, ProcessorsType>::write(
_w, ErrorType(make_field<"error">(_err.what())), _parent
);
return Nothing {};
};
_r.transform(write_t).or_else(write_err);
}
static schema::Type to_schema(
std::map<std::string, schema::Type>* _definitions
) {
return Parser<R, W, std::remove_cvref_t<T>, ProcessorsType>::to_schema(
_definitions
);
}
};
} // namespace parsing
} // namespace rfl
#endif