Merge pull request #341 from qicosmos/add_index_of

Author: qicosmos

iguana/ylt/reflection/member_value.hpp

@@ -176,6 +176,13 @@ inline size_t index_of(T& t, Field& value) {
   return std::distance(offset_arr.begin(), it);
 }
 
+template <typename Member>
+inline size_t index_of(Member member) {
+  using T = typename member_traits<Member>::owner_type;
+  static auto& t = internal::get_fake_object<T>();
+  return index_of(t, t.*member);
+}
+
 template <typename T, typename Field>
 inline constexpr std::string_view name_of(T& t, Field& value) {
   size_t index = index_of(t, value);

test/test_reflection.cpp

@@ -374,6 +374,11 @@ TEST_CASE("test macros") {
   constexpr auto idx2 = index_of<&simple2::id>();
   static_assert(idx2 == 1);
 
+  auto i = index_of(&simple::id);
+  CHECK(i == 1);
+  i = index_of(&simple::age);
+  CHECK(i == 3);
+
   constexpr auto arr = get_member_names<simple2>();
   static_assert(arr.size() == 4);
   constexpr auto map = member_names_map<simple2>;