diff --git a/cpp/utils.h b/cpp/utils.h
index db2ba9c..75ba6ca 100644
--- a/cpp/utils.h
+++ b/cpp/utils.h
@@ -26,3 +26,39 @@ bool ReadCsvMetaFile(const std::string& filename, std::list<T>& meta_list)
                                meta_list.emplace_back(t);
                            });
 }
+
+template <typename T1,
+          typename T2>
+static void RepeatedFieldToVector(const T1& t1, T2& t2)
+{
+    for (auto& val : t1) {
+        t2.push_back(val);
+    }
+}
+
+template <typename T1,
+          typename T2>
+static void RepeatedFieldToSet(const T1& t1, T2& t2)
+{
+    for (auto& val : t1) {
+        t2.insert(val);
+    }
+}
+
+template <typename T1,
+          typename T2>
+static void VectorToRepeatedField(const T1& t1, T2& t2)
+{
+    for (auto& val : t1) {
+        *t2.Add() = val;
+    }
+}
+
+template <typename T1,
+          typename T2>
+static void SetToRepeatedField(const T1& t1, T2& t2)
+{
+    for (auto& val : t1) {
+        *t2.Add() = val;
+    }
+}