Reflect optional by Brandon Tolsch

src/messages/ccls_call_hierarchy.cc

@@ -79,7 +79,10 @@ MAKE_REFLECT_STRUCT(Out_CclsCallHierarchy::Entry,
                     callType,
                     numChildren,
                     children);
-MAKE_REFLECT_STRUCT(Out_CclsCallHierarchy, jsonrpc, id, result);
+MAKE_REFLECT_STRUCT_MANDATORY_OPTIONAL(Out_CclsCallHierarchy,
+                                       jsonrpc,
+                                       id,
+                                       result);
 
 bool Expand(MessageHandler* m,
             Out_CclsCallHierarchy::Entry* entry,

src/messages/ccls_inheritance_hierarchy.cc

@@ -60,7 +60,10 @@ MAKE_REFLECT_STRUCT(Out_CclsInheritanceHierarchy::Entry,
                     location,
                     numChildren,
                     children);
-MAKE_REFLECT_STRUCT(Out_CclsInheritanceHierarchy, jsonrpc, id, result);
+MAKE_REFLECT_STRUCT_MANDATORY_OPTIONAL(Out_CclsInheritanceHierarchy,
+                                       jsonrpc,
+                                       id,
+                                       result);
 
 bool Expand(MessageHandler* m,
             Out_CclsInheritanceHierarchy::Entry* entry,

src/messages/ccls_member_hierarchy.cc

@@ -59,7 +59,10 @@ MAKE_REFLECT_STRUCT(Out_CclsMemberHierarchy::Entry,
                     location,
                     numChildren,
                     children);
-MAKE_REFLECT_STRUCT(Out_CclsMemberHierarchy, jsonrpc, id, result);
+MAKE_REFLECT_STRUCT_MANDATORY_OPTIONAL(Out_CclsMemberHierarchy,
+                                       jsonrpc,
+                                       id,
+                                       result);
 
 bool Expand(MessageHandler* m,
             Out_CclsMemberHierarchy::Entry* entry,

src/messages/text_document_hover.cc

@@ -57,20 +57,10 @@ struct Out_TextDocumentHover : public lsOutMessage<Out_TextDocumentHover> {
   std::optional<Result> result;
 };
 MAKE_REFLECT_STRUCT(Out_TextDocumentHover::Result, contents, range);
-void Reflect(Writer& visitor, Out_TextDocumentHover& value) {
-  REFLECT_MEMBER_START();
-  REFLECT_MEMBER(jsonrpc);
-  REFLECT_MEMBER(id);
-  if (value.result)
-    REFLECT_MEMBER(result);
-  else {
-    // Empty optional<> is elided by the default serializer, we need to write
-    // |null| to be compliant with the LSP.
-    visitor.Key("result");
-    visitor.Null();
-  }
-  REFLECT_MEMBER_END();
-}
+MAKE_REFLECT_STRUCT_MANDATORY_OPTIONAL(Out_TextDocumentHover,
+                                       jsonrpc,
+                                       id,
+                                       result);
 
 struct Handler_TextDocumentHover : BaseMessageHandler<In_TextDocumentHover> {
   MethodType GetMethodType() const override { return kMethodType; }

src/messages/workspace_execute_command.cc

@@ -20,14 +20,6 @@ struct Out_WorkspaceExecuteCommand
 };
 MAKE_REFLECT_STRUCT(Out_WorkspaceExecuteCommand, jsonrpc, id, result);
 
-void Reflect(Writer& visitor, Out_WorkspaceExecuteCommand& value) {
-  REFLECT_MEMBER_START();
-  REFLECT_MEMBER(jsonrpc);
-  REFLECT_MEMBER(id);
-  REFLECT_MEMBER(result);
-  REFLECT_MEMBER_END();
-}
-
 struct Handler_WorkspaceExecuteCommand
     : BaseMessageHandler<In_WorkspaceExecuteCommand> {
   MethodType GetMethodType() const override { return kMethodType; }

src/serializer.h

@@ -19,6 +19,7 @@
 enum class SerializeFormat { Binary, Json };
 
 struct JsonNull {};
+struct mandatory_optional_tag {};
 
 class Reader {
  public:
@@ -77,6 +78,8 @@ struct IndexFile;
 #define REFLECT_MEMBER_START() ReflectMemberStart(visitor, value)
 #define REFLECT_MEMBER_END() ReflectMemberEnd(visitor, value);
 #define REFLECT_MEMBER(name) ReflectMember(visitor, #name, value.name)
+#define REFLECT_MEMBER_MANDATORY_OPTIONAL(name) \
+  ReflectMember(visitor, #name, value.name, mandatory_optional_tag{})
 #define REFLECT_MEMBER2(name, value) ReflectMember(visitor, name, value)
 
 #define MAKE_REFLECT_TYPE_PROXY(type_name) \
@@ -93,6 +96,8 @@ struct IndexFile;
   }
 
 #define _MAPPABLE_REFLECT_MEMBER(name) REFLECT_MEMBER(name);
+#define _MAPPABLE_REFLECT_MEMBER_MANDATORY_OPTIONAL(name) \
+  REFLECT_MEMBER_MANDATORY_OPTIONAL(name);
 
 #define MAKE_REFLECT_EMPTY_STRUCT(type, ...)     \
   template <typename TVisitor>                   \
@@ -109,6 +114,14 @@ struct IndexFile;
     REFLECT_MEMBER_END();                            \
   }
 
+#define MAKE_REFLECT_STRUCT_MANDATORY_OPTIONAL(type, ...)               \
+  template <typename TVisitor>                                          \
+  void Reflect(TVisitor& visitor, type& value) {                        \
+    REFLECT_MEMBER_START();                                             \
+    MACRO_MAP(_MAPPABLE_REFLECT_MEMBER_MANDATORY_OPTIONAL, __VA_ARGS__) \
+    REFLECT_MEMBER_END();                                               \
+  }
+
 // clang-format off
 // Config has many fields, we need to support at least its number of fields.
 #define NUM_VA_ARGS_IMPL(_1,_2,_3,_4,_5,_6,_7,_8,_9,_10,_11,_12,_13,_14,_15,_16,_17,_18,_19,_20,_21,_22,_23,_24,_25,_26,_27,_28,_29,_30,N,...) N
@@ -243,6 +256,15 @@ void ReflectMember(Writer& visitor, const char* name, Maybe<T>& value) {
   }
 }
 
+template <typename T>
+void ReflectMember(Writer& visitor,
+                   const char* name,
+                   T& value,
+                   mandatory_optional_tag) {
+  visitor.Key(name);
+  Reflect(visitor, value);
+}
+
 // std::vector
 template <typename T>
 void Reflect(Reader& visitor, std::vector<T>& values) {