Pull out Buildable into its own file/header in libnixstore

src/libstore/buildable.cc

@@ -0,0 +1,33 @@
+#include "buildable.hh"
+#include "store-api.hh"
+
+#include <nlohmann/json.hpp>
+
+namespace nix {
+
+nlohmann::json BuildableOpaque::toJSON(ref<Store> store) const {
+    nlohmann::json res;
+    res["path"] = store->printStorePath(path);
+    return res;
+}
+
+nlohmann::json BuildableFromDrv::toJSON(ref<Store> store) const {
+    nlohmann::json res;
+    res["drvPath"] = store->printStorePath(drvPath);
+    for (const auto& [output, path] : outputs) {
+        res["outputs"][output] = path ? store->printStorePath(*path) : "";
+    }
+    return res;
+}
+
+nlohmann::json buildablesToJSON(const Buildables & buildables, ref<Store> store) {
+    auto res = nlohmann::json::array();
+    for (const Buildable & buildable : buildables) {
+        std::visit([&res, store](const auto & buildable) {
+            res.push_back(buildable.toJSON(store));
+        }, buildable);
+    }
+    return res;
+}
+
+}

src/libstore/buildable.hh

@@ -0,0 +1,34 @@
+#pragma once
+
+#include "util.hh"
+#include "path.hh"
+
+#include <optional>
+
+#include <nlohmann/json_fwd.hpp>
+
+namespace nix {
+
+class Store;
+
+struct BuildableOpaque {
+    StorePath path;
+    nlohmann::json toJSON(ref<Store> store) const;
+};
+
+struct BuildableFromDrv {
+    StorePath drvPath;
+    std::map<std::string, std::optional<StorePath>> outputs;
+    nlohmann::json toJSON(ref<Store> store) const;
+};
+
+typedef std::variant<
+    BuildableOpaque,
+    BuildableFromDrv
+> Buildable;
+
+typedef std::vector<Buildable> Buildables;
+
+nlohmann::json buildablesToJSON(const Buildables & buildables, ref<Store> store);
+
+}