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diff --git a/clang-tools-extra/clangd/JSONRPCDispatcher.h b/clang-tools-extra/clangd/JSONRPCDispatcher.h
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+++ b/clang-tools-extra/clangd/JSONRPCDispatcher.h
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+//===--- JSONRPCDispatcher.h - Main JSON parser entry point -----*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANGD_JSONRPCDISPATCHER_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANGD_JSONRPCDISPATCHER_H
+
+#include "clang/Basic/LLVM.h"
+#include "llvm/ADT/StringMap.h"
+#include "llvm/Support/YAMLParser.h"
+
+namespace clang {
+namespace clangd {
+
+/// Callback for messages sent to the server, called by the JSONRPCDispatcher.
+class Handler {
+public:
+  Handler(llvm::raw_ostream &Outs, llvm::raw_ostream &Logs)
+      : Outs(Outs), Logs(Logs) {}
+  virtual ~Handler() = default;
+
+  /// Called when the server receives a method call. This is supposed to return
+  /// a result on Outs. The default implementation returns an "unknown method"
+  /// error to the client and logs a warning.
+  virtual void handleMethod(llvm::yaml::MappingNode *Params, StringRef ID);
+  /// Called when the server receives a notification. No result should be
+  /// written to Outs. The default implemetation logs a warning.
+  virtual void handleNotification(llvm::yaml::MappingNode *Params);
+
+protected:
+  llvm::raw_ostream &Outs;
+  llvm::raw_ostream &Logs;
+
+  /// Helper to write a JSONRPC result to Outs.
+  void writeMessage(const Twine &Message);
+};
+
+/// Main JSONRPC entry point. This parses the JSONRPC "header" and calls the
+/// registered Handler for the method received.
+class JSONRPCDispatcher {
+public:
+  /// Create a new JSONRPCDispatcher. UnknownHandler is called when an unknown
+  /// method is received.
+  JSONRPCDispatcher(std::unique_ptr<Handler> UnknownHandler)
+      : UnknownHandler(std::move(UnknownHandler)) {}
+
+  /// Registers a Handler for the specified Method.
+  void registerHandler(StringRef Method, std::unique_ptr<Handler> H);
+
+  /// Parses a JSONRPC message and calls the Handler for it.
+  bool call(StringRef Content) const;
+
+private:
+  llvm::StringMap<std::unique_ptr<Handler>> Handlers;
+  std::unique_ptr<Handler> UnknownHandler;
+};
+
+} // namespace clangd
+} // namespace clang
+
+#endif