Added comments to XML

Author: liuzicheng1987

include/rfl/xml/Writer.hpp

@@ -10,8 +10,7 @@
 #include "../always_false.hpp"
 #include "../common.hpp"
 
-namespace rfl {
-namespace xml {
+namespace rfl ::xml {
 
 struct RFL_API Writer {
   struct XMLOutputArray {
@@ -59,6 +58,12 @@ struct RFL_API Writer {
                                       const size_t _size,
                                       OutputObjectType* _parent) const;
 
+  void add_comment_to_array(const std::string_view& _comment,
+                            OutputArrayType* _parent) const;
+
+  void add_comment_to_object(const std::string_view& _comment,
+                             OutputObjectType* _parent) const;
+
   OutputObjectType add_object_to_array(const size_t _size,
                                        OutputArrayType* _parent) const;
 
@@ -95,7 +100,7 @@ struct RFL_API Writer {
   template <class T>
   decltype(auto) to_string(const T& _val) const {
     if constexpr (std::is_same<std::remove_cvref_t<T>, std::string>()) {
-      return _val; // Return reference to avoid expensive string copy.
+      return _val;  // Return reference to avoid expensive string copy.
     } else if constexpr (std::is_same<std::remove_cvref_t<T>, bool>()) {
       return _val ? "true" : "false";
     } else if constexpr (std::is_floating_point<std::remove_cvref_t<T>>() ||
@@ -121,7 +126,6 @@ struct RFL_API Writer {
   std::string root_name_;
 };
 
-}  // namespace xml
-}  // namespace rfl
+}  // namespace rfl::xml
 
 #endif  // RFL_XML_WRITER_HPP_

src/rfl/xml/Writer.cpp

@@ -38,27 +38,23 @@ Writer::Writer(const Ref<pugi::xml_node>& _root, const std::string& _root_name)
 Writer::~Writer() = default;
 
 Writer::OutputArrayType Writer::array_as_root(const size_t /*_size*/) const {
-  auto node_child =
-      Ref<pugi::xml_node>::make(root_->append_child(root_name_));
+  auto node_child = Ref<pugi::xml_node>::make(root_->append_child(root_name_));
   return OutputArrayType(root_name_, node_child);
 }
 
 Writer::OutputObjectType Writer::object_as_root(const size_t /*_size*/) const {
-  auto node_child =
-      Ref<pugi::xml_node>::make(root_->append_child(root_name_));
+  auto node_child = Ref<pugi::xml_node>::make(root_->append_child(root_name_));
   return OutputObjectType(node_child);
 }
 
 Writer::OutputVarType Writer::null_as_root() const {
-  auto node_child =
-      Ref<pugi::xml_node>::make(root_->append_child(root_name_));
+  auto node_child = Ref<pugi::xml_node>::make(root_->append_child(root_name_));
   return OutputVarType(node_child);
 }
 
 Writer::OutputVarType Writer::value_as_root_impl(
     const std::string& _str) const {
-  auto node_child =
-      Ref<pugi::xml_node>::make(root_->append_child(root_name_));
+  auto node_child = Ref<pugi::xml_node>::make(root_->append_child(root_name_));
   node_child->append_child(pugi::node_pcdata).set_value(_str);
   return OutputVarType(node_child);
 }
@@ -74,6 +70,16 @@ Writer::OutputArrayType Writer::add_array_to_object(
   return OutputArrayType(_name, _parent->node_);
 }
 
+void Writer::add_comment_to_array(const std::string_view& _comment,
+                                  OutputArrayType* _parent) const {
+  _parent->node_->append_child(pugi::node_comment).set_value(_comment);
+}
+
+void Writer::add_comment_to_object(const std::string_view& _comment,
+                                   OutputObjectType* _parent) const {
+  _parent->node_->append_child(pugi::node_comment).set_value(_comment);
+}
+
 Writer::OutputVarType Writer::add_value_to_array_impl(
     const std::string& _str, OutputArrayType* _parent) const {
   auto node_child =

tests/xml/test_comment.cpp

@@ -0,0 +1,32 @@
+#include <rfl.hpp>
+#include <string>
+#include <vector>
+
+#include "write_and_read.hpp"
+
+namespace test_comment {
+
+struct Person {
+  std::string first_name;
+  std::string last_name;
+  rfl::Commented<std::string> town;
+};
+
+TEST(xml, test_comment) {
+  const auto homer = Person{.first_name = "Homer",
+                            .last_name = "Simpson",
+                            .town = rfl::Commented<std::string>(
+                                "Springfield", "The town where Homer lives")};
+
+  const auto xml_str = rfl::xml::write(homer);
+
+  EXPECT_EQ(xml_str, R"(<?xml version="1.0" encoding="UTF-8"?>
+<Person>
+    <first_name>Homer</first_name>
+    <last_name>Simpson</last_name>
+    <town>Springfield</town>
+    <!--The town where Homer lives-->
+</Person>
+)");
+}
+}  // namespace test_comment