From 65e46af97a9622ca5be9658f310e700f6b4929ed Mon Sep 17 00:00:00 2001
From: Fangrui Song <i@maskray.me>
Date: Fri, 23 Nov 2018 10:08:44 -0800
Subject: [PATCH] Refactor ReplyOnce & error if InitializeParams.rootUri is
 null

---
 src/lsp.hh                              |  7 -------
 src/message_handler.cc                  | 28 +++++++------------------
 src/message_handler.hh                  |  5 +++--
 src/messages/initialize.cc              |  4 +++-
 src/messages/textDocument_formatting.cc | 14 +++++--------
 5 files changed, 19 insertions(+), 39 deletions(-)

diff --git a/src/lsp.hh b/src/lsp.hh
index b6a60877..2c4c735f 100644
--- a/src/lsp.hh
+++ b/src/lsp.hh
@@ -62,15 +62,8 @@ enum class ErrorCode {
 };
 
 struct ResponseError {
-  // A number indicating the error type that occurred.
   ErrorCode code;
-
-  // A string providing a short description of the error.
   std::string message;
-
-  // A Primitive or Structured value that contains additional
-  // information about the error. Can be omitted.
-  // std::optional<D> data;
 };
 
 constexpr char ccls_xref[] = "ccls.xref";
diff --git a/src/message_handler.cc b/src/message_handler.cc
index 804bbc92..69a2a3ca 100644
--- a/src/message_handler.cc
+++ b/src/message_handler.cc
@@ -207,21 +207,13 @@ void MessageHandler::Run(InMessage &msg) {
       try {
         it->second(reader, reply);
       } catch (std::invalid_argument &ex) {
-        ResponseError err;
-        err.code = ErrorCode::InvalidParams;
-        err.message = "invalid params of " + msg.method + ": " + ex.what();
-        reply.Error(err);
+        reply.Error(ErrorCode::InvalidParams,
+                    "invalid params of " + msg.method + ": " + ex.what());
       } catch (...) {
-        ResponseError err;
-        err.code = ErrorCode::InternalError;
-        err.message = "failed to process " + msg.method;
-        reply.Error(err);
+        reply.Error(ErrorCode::InternalError, "failed to process " + msg.method);
       }
     } else {
-      ResponseError err;
-      err.code = ErrorCode::MethodNotFound;
-      err.message = "unknown request " + msg.method;
-      reply.Error(err);
+      reply.Error(ErrorCode::MethodNotFound, "unknown request " + msg.method);
     }
   } else {
     auto it = method2notification.find(msg.method);
@@ -260,14 +252,10 @@ QueryFile *MessageHandler::FindFile(ReplyOnce &reply,
         has_entry |= folder.path2entry_index.count(path);
     }
     ResponseError err;
-    if (has_entry) {
-      err.code = ErrorCode::ServerNotInitialized;
-      err.message = path + " is being indexed";
-    } else {
-      err.code = ErrorCode::InternalError;
-      err.message = "unable to find " + path;
-    }
-    reply.Error(err);
+    if (has_entry)
+      reply.Error(ErrorCode::ServerNotInitialized, path + " is being indexed");
+    else
+      reply.Error(ErrorCode::InternalError, "unable to find " + path);
   }
 
   return ret;
diff --git a/src/message_handler.hh b/src/message_handler.hh
index 2cbee9be..afc169b5 100644
--- a/src/message_handler.hh
+++ b/src/message_handler.hh
@@ -199,11 +199,12 @@ using Callback = std::function<void(Res*)>;
 
 struct ReplyOnce {
   RequestId id;
-  template <typename Res> void operator()(Res &result) const {
+  template <typename Res> void operator()(Res &&result) const {
     if (id.Valid())
       pipeline::Reply(id, [&](Writer &w) { Reflect(w, result); });
   }
-  template <typename Err> void Error(Err &err) const {
+  void Error(ErrorCode code, std::string message) const {
+    ResponseError err{code, std::move(message)};
     if (id.Valid())
       pipeline::ReplyError(id, [&](Writer &w) { Reflect(w, err); });
   }
diff --git a/src/messages/initialize.cc b/src/messages/initialize.cc
index 7c93511e..991a2359 100644
--- a/src/messages/initialize.cc
+++ b/src/messages/initialize.cc
@@ -342,8 +342,10 @@ void Initialize(MessageHandler *m, InitializeParam &param, ReplyOnce &reply) {
 void MessageHandler::initialize(Reader &reader, ReplyOnce &reply) {
   InitializeParam param;
   Reflect(reader, param);
-  if (!param.rootUri)
+  if (!param.rootUri) {
+    reply.Error(ErrorCode::InvalidRequest, "expected rootUri");
     return;
+  }
   Initialize(this, param, reply);
 }
 
diff --git a/src/messages/textDocument_formatting.cc b/src/messages/textDocument_formatting.cc
index 211eac78..271d1a1d 100644
--- a/src/messages/textDocument_formatting.cc
+++ b/src/messages/textDocument_formatting.cc
@@ -70,15 +70,11 @@ std::vector<TextEdit> ReplacementsToEdits(std::string_view code,
 void Format(ReplyOnce &reply, WorkingFile *wfile, tooling::Range range) {
   std::string_view code = wfile->buffer_content;
   auto ReplsOrErr = FormatCode(code, wfile->filename, range);
-  if (ReplsOrErr) {
-    auto result = ReplacementsToEdits(code, *ReplsOrErr);
-    reply(result);
-  } else {
-    ResponseError err;
-    err.code = ErrorCode::UnknownErrorCode;
-    err.message = llvm::toString(ReplsOrErr.takeError());
-    reply.Error(err);
-  }
+  if (ReplsOrErr)
+    reply(ReplacementsToEdits(code, *ReplsOrErr));
+  else
+    reply.Error(ErrorCode::UnknownErrorCode,
+                llvm::toString(ReplsOrErr.takeError()));
 }
 } // namespace