From ebf2fd76b106d5eb8f45ccce0615653108bb99bc Mon Sep 17 00:00:00 2001
From: Yorick van Pelt <yorick@yorickvanpelt.nl>
Date: Wed, 20 Apr 2022 15:41:01 +0200
Subject: [PATCH] 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.
---
src/libutil/experimental-features.cc | 14 ++++++++++++++
src/libutil/experimental-features.hh | 7 +++++++
2 files changed, 21 insertions(+)
diff --git a/src/libutil/experimental-features.cc b/src/libutil/experimental-features.cc
index e033a4116..df37edf57 100644
--- a/src/libutil/experimental-features.cc
+++ b/src/libutil/experimental-features.cc
@@ -58,4 +58,18 @@ std::ostream & operator <<(std::ostream & str, const ExperimentalFeature & featu
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);
+}
+
}
diff --git a/src/libutil/experimental-features.hh b/src/libutil/experimental-features.hh
index 266e41a22..a6d080094 100644
--- a/src/libutil/experimental-features.hh
+++ b/src/libutil/experimental-features.hh
@@ -51,4 +51,11 @@ public:
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&);
+
}