Fabric: New nice way to deal with DebugStringConvertible items

Summary:
No macros in product code.
(Not all callsites are converted yet.)

Reviewed By: mdvacca

Differential Revision: D7797561

fbshipit-source-id: da899421bf99669a0e0a2b83df6004daf14355c2

ReactCommon/fabric/debug/debugStringConvertibleUtils.cpp

@@ -0,0 +1,25 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#include "debugStringConvertibleUtils.h"
+
+namespace facebook {
+namespace react {
+
+SharedDebugStringConvertibleList operator+(const SharedDebugStringConvertibleList &lhs, const SharedDebugStringConvertibleList &rhs) {
+  SharedDebugStringConvertibleList result = {};
+  std::move(lhs.begin(), lhs.end(), std::back_inserter(result));
+  std::move(rhs.begin(), rhs.end(), std::back_inserter(result));
+  return result;
+}
+
+SharedDebugStringConvertible debugStringConvertibleItem(std::string name, DebugStringConvertible value, std::string defaultValue) {
+  return debugStringConvertibleItem(name, value.getDebugDescription(), defaultValue);
+}
+
+} // namespace react
+} // namespace facebook