[Lldb-commits] [lldb] [lldb-dap] Updating RequestHandler to encode/decode arguments and response. (PR #130090)

[Adrian Vogelsgesang via lldb-commits]

================
@@ -57,235 +68,288 @@ class RequestHandler {
   DAP &dap;
 };
 
-class AttachRequestHandler : public RequestHandler {
-public:
-  using RequestHandler::RequestHandler;
+/// Base class for handling DAP requests. Handlers should declare their
+/// arguments and response body types like:
+///
+/// class MyRequestHandler : public RequestHandler<Arguments, ResponseBody> {
+///   ....
+/// };
+template <typename Args, typename Body>
+class RequestHandler : public BaseRequestHandler {
+  using BaseRequestHandler::BaseRequestHandler;
+
+  void operator()(const llvm::json::Object &request) const override {
+    /* no-op, the other overload handles json coding. */
+  }
+
+  void operator()(const protocol::Request &request) const override {
+    protocol::Response response;
+    response.request_seq = request.seq;
+    response.command = request.command;
+    Args arguments;
+    llvm::json::Path::Root root;
+    if (request.rawArguments &&
+        !fromJSON(request.rawArguments, arguments, root)) {
+      std::string parseFailure;
+      llvm::raw_string_ostream OS(parseFailure);
+      root.printErrorContext(request.rawArguments, OS);
+      response.success = false;
+      response.message = parseFailure;
----------------
vogelsgesang wrote:

message is not meant to contain a user-readable string, It is meant to contain an enum-like value.

I know that large parts of DAP don't do this correctly. But for newly written code, I think we should directly be protocol-compliant. Or at least add a `FIXME` similar to how you did further down

We might want to extend our error message enum to also have an `protocolViolation` in addition to `cancelled` and `notStopped`. The more descriptive `parseFailure` string should go into the `message` inside the `ErrorResponse`.
I think this one we would like to mark as `showUser: true`?

https://github.com/llvm/llvm-project/pull/130090