fix/src/libutil/experimental-features.hh

#pragma once

#include "comparator.hh"
#include "error.hh"
#include "nlohmann/json_fwd.hpp"
#include "types.hh"

namespace nix {

/**
 * The list of available experimental features.
 *
 * If you update this, don’t forget to also change the map defining their
 * string representation in the corresponding `.cc` file.
 **/
enum struct ExperimentalFeature
{
    CaDerivations,
    ImpureDerivations,
    Flakes,
    NixCommand,
    RecursiveNix,
    NoUrlLiterals,
    FetchClosure,
};

/**
 * Just because writing `ExperimentalFeature::CaDerivations` is way too long
 */
using Xp = ExperimentalFeature;

const std::optional<ExperimentalFeature> parseExperimentalFeature(
        const std::string_view & name);
std::string_view showExperimentalFeature(const ExperimentalFeature);

std::ostream & operator<<(
        std::ostream & str,
        const ExperimentalFeature & feature);

/**
 * Parse a set of strings to the corresponding set of experimental features,
 * ignoring (but warning for) any unkwown feature.
 */
std::set<ExperimentalFeature> parseFeatures(const std::set<std::string> &);

class MissingExperimentalFeature : public Error
{
public:
    ExperimentalFeature missingFeature;

    MissingExperimentalFeature(ExperimentalFeature);
};

/**
 * Semi-magic conversion to and from json.
 * See the nlohmann/json readme for more details.
 */
void to_json(nlohmann::json &, const ExperimentalFeature &);
void from_json(const nlohmann::json &, ExperimentalFeature &);

}