[json schema] use non-deprecated $defs; Add $comment option

Author: AndrewNolte

include/rfl/json/schema/JSONSchema.hpp

@@ -15,8 +15,9 @@ template <class T>
 struct JSONSchema {
   Rename<"$schema", Literal<"https://json-schema.org/draft/2020-12/schema">>
       schema{};
+  rfl::Rename<"$comment", std::optional<std::string>> comment{};
   Flatten<T> root{};
-  std::map<std::string, Type> definitions{};
+  rfl::Rename<"$defs", std::map<std::string, Type>> definitions{};
 };
 
 }  // namespace rfl::json::schema

include/rfl/json/to_schema.hpp

@@ -33,15 +33,16 @@ struct TypeHelper<rfl::Variant<Ts...>> {
 
 std::string to_schema_internal_schema(
     const parsing::schema::Definition& internal_schema, const yyjson_write_flag,
-    const bool _no_required);
+    const bool _no_required, std::string comment = "");
 
 /// Returns the JSON schema for a class.
 template <class T, class... Ps>
-std::string to_schema(const yyjson_write_flag _flag = 0) {
+std::string to_schema(const yyjson_write_flag _flag = 0,
+                      std::string comment = "") {
   using P = Processors<Ps...>;
   const auto internal_schema = parsing::schema::make<Reader, Writer, T, P>();
   return to_schema_internal_schema(internal_schema, _flag,
-                                   P::default_if_missing_);
+                                   P::default_if_missing_, comment);
 }
 }  // namespace rfl::json
 

src/rfl/json/to_schema.cpp

@@ -263,7 +263,7 @@ schema::Type type_to_json_schema_type(const parsing::schema::Type& _type,
 
     } else if constexpr (std::is_same<T, Type::Reference>()) {
       return schema::Type{
-          .value = schema::Type::Reference{.ref = "#/definitions/" + _t.name_}};
+          .value = schema::Type::Reference{.ref = "#/$defs/" + _t.name_}};
 
     } else if constexpr (std::is_same<T, Type::StringMap>()) {
       return schema::Type{
@@ -297,7 +297,8 @@ schema::Type type_to_json_schema_type(const parsing::schema::Type& _type,
 
 std::string to_schema_internal_schema(
     const parsing::schema::Definition& internal_schema,
-    const yyjson_write_flag _flag, const bool _no_required) {
+    const yyjson_write_flag _flag, const bool _no_required,
+    std::string comment) {
   auto definitions = std::map<std::string, schema::Type>();
   for (const auto& [k, v] : internal_schema.definitions_) {
     definitions[k] = type_to_json_schema_type(v, _no_required);
@@ -306,8 +307,11 @@ std::string to_schema_internal_schema(
       typename TypeHelper<schema::Type::ReflectionType>::JSONSchemaType;
   const auto to_schema = [&](auto&& _root) -> JSONSchemaType {
     using U = std::decay_t<decltype(_root)>;
-    return schema::JSONSchema<U>{.root = std::move(_root),
-                                 .definitions = definitions};
+    return schema::JSONSchema<U>{
+        .comment = comment.size() ? std::optional(comment) : std::nullopt,
+        .root = std::forward<decltype(_root)>(_root),
+        .definitions = definitions,
+    };
   };
   auto root = type_to_json_schema_type(internal_schema.root_, _no_required);
   const auto json_schema = rfl::visit(to_schema, std::move(root.value));