partial from json

qicosmos · Apr 29, 2024 · df63989 · df63989
1 parent fb6e6d5
commit df63989
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Showing 3 changed files with 137 additions and 4 deletions.
diff --git a/iguana/json_reader.hpp b/iguana/json_reader.hpp
@@ -644,6 +644,31 @@ IGUANA_INLINE void from_json(T &value, const View &view) {
   from_json(value, std::begin(view), std::end(view));
 }
 
+template <
+    auto member,
+    typename Parant = typename member_tratis<decltype(member)>::owner_type,
+    typename T>
+IGUANA_INLINE void from_json(T &value, std::string_view str) {
+  constexpr size_t duplicate_count =
+      iguana::duplicate_count<std::remove_reference_t<Parant>, member>();
+  static_assert(duplicate_count != 1, "the member is not belong to the object");
+  static_assert(duplicate_count == 2, "has duplicate field name");
+
+  constexpr auto name = name_of<member>();
+  constexpr size_t index = index_of<member>();
+  constexpr size_t member_count = member_count_of<member>();
+  str = str.substr(str.find(name) + name.size());
+  size_t pos = str.find(":") + 1;
+  if constexpr (index == member_count - 1) {  // last field
+    str = str.substr(pos, str.find("}") - pos);
+  }
+  else {
+    str = str.substr(pos, str.find(",") - pos);
+  }
+
+  detail::from_json_impl(value.*member, std::begin(str), std::end(str));
+}
+
 template <typename T, typename View,
           std::enable_if_t<json_view_v<View>, int> = 0>
 IGUANA_INLINE void from_json(T &value, const View &view,

diff --git a/iguana/reflection.hpp b/iguana/reflection.hpp
@@ -942,10 +942,7 @@ constexpr bool get_index_imple() {
 #else
 template <typename T, typename U>
 constexpr bool get_index_imple(T ptr, U ele) {
-  if constexpr (std::is_same_v<
-                    typename iguana::member_tratis<decltype(ptr)>::value_type,
-                    typename iguana::member_tratis<
-                        decltype(ele)>::value_type>) {
+  if constexpr (std::is_same_v<decltype(ptr), decltype(ele)>) {
     if (ele == ptr) {
       return true;
     }
@@ -999,6 +996,53 @@ constexpr auto name_of() {
   return std::string_view(s.data(), s.size());
 }
 
+template <auto member>
+constexpr auto member_count_of() {
+  using T = typename member_tratis<decltype(member)>::owner_type;
+  using M = Reflect_members<T>;
+  return M::value();
+}
+
+template <typename T, auto member>
+constexpr size_t duplicate_count();
+
+template <auto ptr>
+constexpr void check_duplicate(auto member, size_t &index) {
+  using value_type = typename member_tratis<decltype(member)>::value_type;
+
+  if (detail::get_index_imple(ptr, member)) {
+    index++;
+  }
+
+  if constexpr (is_reflection_v<value_type>) {
+    index += iguana::duplicate_count<value_type, ptr>();
+  }
+}
+
+template <typename T, auto member>
+constexpr size_t duplicate_count() {
+  using M = Reflect_members<T>;
+  constexpr auto name = name_of<member>();
+  constexpr auto arr = M::arr();
+
+  constexpr auto tp = M::apply_impl();
+  size_t index = 0;
+  std::apply(
+      [&](auto... ele) {
+        (check_duplicate<member>(ele, index), ...);
+      },
+      tp);
+
+  for (auto &s : arr) {
+    if (s == name) {
+      index++;
+      break;
+    }
+  }
+
+  return index;
+}
+
 template <typename T>
 constexpr const std::string_view get_fields() {
   using M = Reflect_members<T>;

diff --git a/test/test.cpp b/test/test.cpp
@@ -821,6 +821,70 @@ TEST_CASE("parse some other char") {
   CHECK(p.name == "tom");
 }
 
+struct some_test_t {
+  int id1;
+  std::string name;
+};
+REFLECTION(some_test_t, id1, name);
+
+struct dummy_nest_t {
+  int id;
+  some_test_t t;
+};
+REFLECTION(dummy_nest_t, id, t);
+
+struct some_test_t1 {
+  int id;
+  std::string name;
+};
+REFLECTION(some_test_t1, id, name);
+
+struct dummy_nest_t1 {
+  int id;
+  some_test_t1 t;
+};
+REFLECTION(dummy_nest_t1, id, t);
+
+TEST_CASE("partial from json") {
+  constexpr size_t count1 =
+      iguana::duplicate_count<dummy_nest_t, &some_test_t::name>();
+  static_assert(count1 == 2);
+  constexpr size_t count2 =
+      iguana::duplicate_count<dummy_nest_t, &dummy_nest_t::t>();
+  static_assert(count2 == 2);
+  constexpr size_t count3 =
+      iguana::duplicate_count<dummy_nest_t, &dummy_nest_t::id>();
+  static_assert(count3 == 2);
+
+  constexpr size_t count5 =
+      iguana::duplicate_count<dummy_nest_t1, &dummy_nest_t1::id>();
+  static_assert(count5 == 3);
+  constexpr size_t count4 =
+      iguana::duplicate_count<dummy_nest_t, &person::name>();
+  static_assert(count4 == 1);
+
+  dummy_nest_t t{42, {43, "tom"}};
+  std::string str;
+  iguana::to_json(t, str);
+
+  {
+    dummy_nest_t t1;
+    iguana::from_json<&dummy_nest_t::id>(t1, str);
+    CHECK(t1.id == 42);
+  }
+  {
+    dummy_nest_t t1;
+    iguana::from_json<&dummy_nest_t::t>(t1, str);
+    CHECK(t1.t.name == "tom");
+  }
+
+  {
+    some_test_t t1;
+    iguana::from_json<&some_test_t::name, dummy_nest_t>(t1, str);
+    CHECK(t1.name == "tom");
+  }
+}
+
 TEST_CASE("index_of name_of") {
   constexpr size_t idx1 = iguana::index_of<&point_t::y>();
   static_assert(idx1 == 1);