lix/src/libutil/experimental-features.cc
Yorick ebf2fd76b1
Add custom to_json and from_json functions for ExperimentalFeature
nix show-config --json was serializing experimental features as ints.
nlohmann::json will automatically use these definitions to serialize
and deserialize ExperimentalFeatures.

Strictly, we don't use the from_json instance yet, it's provided for
completeness and hopefully future use.
2022-04-20 15:41:01 +02:00

76 lines
2.2 KiB
C++

#include "experimental-features.hh"
#include "util.hh"
#include "nlohmann/json.hpp"
namespace nix {
std::map<ExperimentalFeature, std::string> stringifiedXpFeatures = {
{ Xp::CaDerivations, "ca-derivations" },
{ Xp::ImpureDerivations, "impure-derivations" },
{ Xp::Flakes, "flakes" },
{ Xp::NixCommand, "nix-command" },
{ Xp::RecursiveNix, "recursive-nix" },
{ Xp::NoUrlLiterals, "no-url-literals" },
{ Xp::FetchClosure, "fetch-closure" },
};
const std::optional<ExperimentalFeature> parseExperimentalFeature(const std::string_view & name)
{
using ReverseXpMap = std::map<std::string_view, ExperimentalFeature>;
static auto reverseXpMap = []()
{
auto reverseXpMap = std::make_unique<ReverseXpMap>();
for (auto & [feature, name] : stringifiedXpFeatures)
(*reverseXpMap)[name] = feature;
return reverseXpMap;
}();
if (auto feature = get(*reverseXpMap, name))
return *feature;
else
return std::nullopt;
}
std::string_view showExperimentalFeature(const ExperimentalFeature feature)
{
return stringifiedXpFeatures.at(feature);
}
std::set<ExperimentalFeature> parseFeatures(const std::set<std::string> & rawFeatures)
{
std::set<ExperimentalFeature> res;
for (auto & rawFeature : rawFeatures) {
if (auto feature = parseExperimentalFeature(rawFeature))
res.insert(*feature);
}
return res;
}
MissingExperimentalFeature::MissingExperimentalFeature(ExperimentalFeature feature)
: Error("experimental Nix feature '%1%' is disabled; use '--extra-experimental-features %1%' to override", showExperimentalFeature(feature))
, missingFeature(feature)
{}
std::ostream & operator <<(std::ostream & str, const ExperimentalFeature & feature)
{
return str << showExperimentalFeature(feature);
}
void to_json(nlohmann::json& j, const ExperimentalFeature& feature) {
j = showExperimentalFeature(feature);
}
void from_json(const nlohmann::json& j, ExperimentalFeature& feature) {
const std::string input = j;
const auto parsed = parseExperimentalFeature(input);
if (parsed.has_value())
feature = *parsed;
else
throw Error("Unknown experimental feature '%s' in JSON input", input);
}
}