draconisplusplus/include/rfl/parsing/Parser_variant.hpp
2024-05-31 22:59:00 -04:00

111 lines
3.7 KiB
C++

#ifndef RFL_PARSING_PARSER_VARIANT_HPP_
#define RFL_PARSING_PARSER_VARIANT_HPP_
#include <map>
#include <optional>
#include <type_traits>
#include <variant>
#include "../Ref.hpp"
#include "../Result.hpp"
#include "../always_false.hpp"
#include "FieldVariantParser.hpp"
#include "Parser_base.hpp"
#include "schema/Type.hpp"
#include "to_single_error_message.hpp"
namespace rfl {
namespace parsing {
template <class R, class W, class... FieldTypes, class ProcessorsType>
requires AreReaderAndWriter<R, W, std::variant<FieldTypes...>>
class Parser<R, W, std::variant<FieldTypes...>, ProcessorsType> {
public:
using InputVarType = typename R::InputVarType;
using OutputVarType = typename W::OutputVarType;
static Result<std::variant<FieldTypes...>> read(
const R& _r, const InputVarType& _var) noexcept {
if constexpr (internal::all_fields<std::tuple<FieldTypes...>>()) {
return FieldVariantParser<R, W, ProcessorsType, FieldTypes...>::read(
_r, _var);
} else {
std::optional<std::variant<FieldTypes...>> result;
std::vector<Error> errors;
read_variant(_r, _var, &result, &errors);
if (result) {
return std::move(*result);
} else {
return Error(
to_single_error_message(errors,
"Could not parse the variant. Each of the "
"possible alternatives failed "
"for the following reasons: ",
100000));
}
}
}
template <class P>
static void write(const W& _w, const std::variant<FieldTypes...>& _variant,
const P& _parent) noexcept {
if constexpr (internal::all_fields<std::tuple<FieldTypes...>>()) {
FieldVariantParser<R, W, ProcessorsType, FieldTypes...>::write(
_w, _variant, _parent);
} else {
const auto handle = [&](const auto& _v) {
using Type = std::remove_cvref_t<decltype(_v)>;
Parser<R, W, Type, ProcessorsType>::write(_w, _v, _parent);
};
return std::visit(handle, _variant);
}
}
template <size_t _i = 0>
static schema::Type to_schema(
std::map<std::string, schema::Type>* _definitions,
std::vector<schema::Type> _types = {}) {
if constexpr (internal::all_fields<std::tuple<FieldTypes...>>()) {
return FieldVariantParser<R, W, ProcessorsType, FieldTypes...>::to_schema(
_definitions);
} else {
using Type = schema::Type;
constexpr size_t size = sizeof...(FieldTypes);
if constexpr (_i == size) {
return Type{Type::AnyOf{.types_ = _types}};
} else {
using U = std::remove_cvref_t<
std::variant_alternative_t<_i, std::variant<FieldTypes...>>>;
_types.push_back(
Parser<R, W, U, ProcessorsType>::to_schema(_definitions));
return to_schema<_i + 1>(_definitions, std::move(_types));
}
}
}
private:
template <int _i = 0>
static void read_variant(const R& _r, const InputVarType& _var,
std::optional<std::variant<FieldTypes...>>* _result,
std::vector<Error>* _errors) noexcept {
constexpr size_t size = sizeof...(FieldTypes);
if constexpr (_i < size) {
using AltType = std::remove_cvref_t<
std::variant_alternative_t<_i, std::variant<FieldTypes...>>>;
auto res = Parser<R, W, AltType, ProcessorsType>::read(_r, _var);
if (res) {
*_result = std::move(*res);
return;
} else {
_errors->emplace_back(*res.error());
return read_variant<_i + 1>(_r, _var, _result, _errors);
}
}
}
};
} // namespace parsing
} // namespace rfl
#endif