Added support for Stream (issue #300)

include/ArduinoJson/StringTraits/StdStream.hpp

@@ -0,0 +1,42 @@
+// Copyright Benoit Blanchon 2014-2016
+// MIT License
+//
+// Arduino JSON library
+// https://github.com/bblanchon/ArduinoJson
+// If you like this project, please add a star!
+
+#pragma once
+
+#include <istream>
+#include "../TypeTraits/EnableIf.hpp"
+#include "../TypeTraits/IsBaseOf.hpp"
+#include "../TypeTraits/RemoveReference.hpp"
+
+namespace ArduinoJson {
+namespace Internals {
+
+struct StdStreamFuncs {
+  class Iterator {
+    std::istream& _stream;
+
+   public:
+    Iterator(std::istream& stream) : _stream(stream) {}
+
+    char next() {
+      return _stream.eof() ? '\0' : static_cast<char>(_stream.get());
+    }
+
+   private:
+    Iterator& operator=(const Iterator&);  // Visual Studio C4512
+  };
+};
+
+template <typename TStream>
+struct StringFuncs<TStream,
+                   // match any type that is derived from std::istream:
+                   typename TypeTraits::EnableIf<TypeTraits::IsBaseOf<
+                       std::istream, typename TypeTraits::RemoveReference<
+                                         TStream>::type>::value>::type>
+    : StdStreamFuncs {};
+}
+}