1 files changed, 46 insertions, 0 deletions
diff --git a/src/libfetchers/tree-info.cc b/src/libfetchers/tree-info.cc
index 5788e94a1..42a19cbc8 100644
--- a/src/libfetchers/tree-info.cc
+++ b/src/libfetchers/tree-info.cc
@@ -11,4 +11,50 @@ StorePath TreeInfo::computeStorePath(Store & store) const
     return store.makeFixedOutputPath(true, narHash, "source");
 }
 
+TreeInfo TreeInfo::fromJson(const nlohmann::json & json)
+{
+    TreeInfo info;
+
+    auto i = json.find("info");
+    if (i != json.end()) {
+        const nlohmann::json & i2(*i);
+
+        auto j = i2.find("narHash");
+        if (j != i2.end())
+            info.narHash = Hash((std::string) *j);
+        else
+            throw Error("attribute 'narHash' missing in lock file");
+
+        j = i2.find("revCount");
+        if (j != i2.end())
+            info.revCount = *j;
+
+        j = i2.find("lastModified");
+        if (j != i2.end())
+            info.lastModified = *j;
+
+        return info;
+    }
+
+    i = json.find("narHash");
+    if (i != json.end()) {
+        info.narHash = Hash((std::string) *i);
+        return info;
+    }
+
+    throw Error("attribute 'info' missing in lock file");
+}
+
+nlohmann::json TreeInfo::toJson() const
+{
+    nlohmann::json json;
+    assert(narHash);
+    json["narHash"] = narHash.to_string(SRI);
+    if (revCount)
+        json["revCount"] = *revCount;
+    if (lastModified)
+        json["lastModified"] = *lastModified;
+    return json;
+}
+
 }