Reorganized polyfills

src/ArduinoJson/Data/IsVariant.hpp

@@ -0,0 +1,17 @@
+// ArduinoJson - arduinojson.org
+// Copyright Benoit Blanchon 2014-2018
+// MIT License
+
+#pragma once
+
+#include "../Polyfills/type_traits.hpp"
+
+namespace ArduinoJson {
+namespace Internals {
+
+class JsonVariantTag {};
+
+template <typename T>
+struct IsVariant : is_base_of<JsonVariantTag, T> {};
+}  // namespace Internals
+}  // namespace ArduinoJson

src/ArduinoJson/Data/ValueSaver.hpp

@@ -6,8 +6,8 @@
 
 #include "../JsonVariant.hpp"
 #include "../Memory/JsonBuffer.hpp"
+#include "../Polyfills/type_traits.hpp"
 #include "../Strings/StringTraits.hpp"
-#include "../TypeTraits/EnableIf.hpp"
 
 namespace ArduinoJson {
 namespace Internals {
@@ -23,7 +23,7 @@ struct ValueSaver {
 
 template <typename Source>
 struct ValueSaver<
-    Source, typename EnableIf<StringTraits<Source>::should_duplicate>::type> {
+    Source, typename enable_if<StringTraits<Source>::should_duplicate>::type> {
   template <typename Destination>
   static bool save(JsonBuffer* buffer, Destination& dest, Source source) {
     if (!StringTraits<Source>::is_null(source)) {
@@ -41,7 +41,7 @@ struct ValueSaver<
 // const char*, const signed char*, const unsigned char*
 template <typename Char>
 struct ValueSaver<
-    Char*, typename EnableIf<!StringTraits<Char*>::should_duplicate>::type> {
+    Char*, typename enable_if<!StringTraits<Char*>::should_duplicate>::type> {
   template <typename Destination>
   static bool save(JsonBuffer*, Destination& dest, Char* source) {
     dest = reinterpret_cast<const char*>(source);