Made sure that to_map returns a result

Author: liuzicheng1987

include/rfl/flexbuf/Reader.hpp

@@ -111,7 +111,7 @@ struct Reader {
     return _var.AsVector();
   }
 
-  std::vector<std::pair<std::string, InputVarType>> to_map(
+  rfl::Result<std::vector<std::pair<std::string, InputVarType>>> to_map(
       const InputObjectType& _obj) const noexcept {
     std::vector<std::pair<std::string, InputVarType>> m;
 

include/rfl/json/Reader.hpp

@@ -113,7 +113,7 @@ struct Reader {
     return f_arr;
   }
 
-  std::vector<std::pair<std::string, InputVarType>> to_map(
+  rfl::Result<std::vector<std::pair<std::string, InputVarType>>> to_map(
       const InputObjectType _obj) const noexcept {
     std::vector<std::pair<std::string, InputVarType>> m;
     yyjson_obj_iter iter;

include/rfl/parsing/FieldVariantParser.hpp

@@ -48,7 +48,7 @@ struct FieldVariantParser {
       return find_matching_alternative(_r, disc_value, var);
     };
 
-    return _r.to_object(_var).transform(to_map).and_then(to_result);
+    return _r.to_object(_var).and_then(to_map).and_then(to_result);
   }
 
   template <class P>

include/rfl/parsing/IsReader.hpp

@@ -61,8 +61,8 @@ concept IsReader = requires(R r, std::string name,
   /// a vector.
   {
     r.to_map(obj)
-    } -> std::same_as<
-        std::vector<std::pair<std::string, typename R::InputVarType>>>;
+    } -> std::same_as<rfl::Result<
+        std::vector<std::pair<std::string, typename R::InputVarType>>>>;
 
   /// Casts var as an InputObjectType.
   {

include/rfl/parsing/MapParser.hpp

@@ -117,17 +117,23 @@ struct MapParser {
         .value();
   }
 
-  static Result<MapType> make_map(const R& _r, const auto& _obj) noexcept {
-    auto m = _r.to_map(_obj);
+  static Result<MapType> iterate_map(const R& _r, const auto& _map) noexcept {
     MapType res;
     try {
-      for (auto& p : m) {
+      for (auto& p : _map) {
         res.insert(get_pair(_r, p));
       }
     } catch (std::exception& e) {
       return Error(e.what());
     }
     return res;
+  };
+
+  static Result<MapType> make_map(const R& _r, const auto& _obj) noexcept {
+    const auto iterate = [&](const auto& _map) {
+      return iterate_map(_r, _map);
+    };
+    return _r.to_map(_obj).and_then(iterate);
   }
 };
 

include/rfl/xml/Reader.hpp

@@ -154,7 +154,7 @@ struct Reader {
     return f_arr;
   }
 
-  std::vector<std::pair<std::string, InputVarType>> to_map(
+  rfl::Result<std::vector<std::pair<std::string, InputVarType>>> to_map(
       const InputObjectType _obj) const noexcept {
     std::vector<std::pair<std::string, InputVarType>> m;
     for (auto child = _obj.node_.first_child(); child;

include/rfl/yaml/Reader.hpp

@@ -104,7 +104,7 @@ struct Reader {
     return f_arr;
   }
 
-  std::vector<std::pair<std::string, InputVarType>> to_map(
+  rfl::Result<std::vector<std::pair<std::string, InputVarType>>> to_map(
       const InputObjectType& _obj) const noexcept {
     std::vector<std::pair<std::string, InputVarType>> m;
     for (const auto& p : _obj.node_) {