Fixed build when another lib does #undef isnan (issue #284)

include/ArduinoJson/Polyfills/math.hpp

@@ -0,0 +1,83 @@
+// 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
+
+// If Visual Studo <= 2012
+#if defined(_MSC_VER) && _MSC_VER <= 1700
+
+#include <float.h>
+
+namespace ArduinoJson {
+namespace Polyfills {
+template <typename T>
+bool isNaN(T x) {
+  return _isnan(x) != 0;
+}
+
+template <typename T>
+bool isInfinity(T x) {
+  return !_finite(x);
+}
+}
+}
+
+#else
+
+#include <math.h>
+
+// GCC warning: "conversion to 'float' from 'double' may alter its value"
+#ifdef __GNUC__
+#if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 6)
+#pragma GCC diagnostic push
+#endif
+#if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 9)
+#pragma GCC diagnostic ignored "-Wfloat-conversion"
+#else
+#pragma GCC diagnostic ignored "-Wconversion"
+#endif
+#endif
+
+// Workaround for libs that #undef isnan or isinf
+// https://github.com/bblanchon/ArduinoJson/issues/284
+#if !defined(isnan) || !defined(isinf)
+namespace std {}
+#endif
+
+namespace ArduinoJson {
+namespace Polyfills {
+
+template <typename T>
+bool isNaN(T x) {
+// Workaround for libs that #undef isnan
+// https://github.com/bblanchon/ArduinoJson/issues/284
+#ifndef isnan
+  using namespace std;
+#endif
+
+  return isnan(x);
+}
+
+template <typename T>
+bool isInfinity(T x) {
+// Workaround for libs that #undef isinf
+// https://github.com/bblanchon/ArduinoJson/issues/284
+#ifndef isinf
+  using namespace std;
+#endif
+
+  return isinf(x);
+}
+
+#if defined(__GNUC__)
+#if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 6)
+#pragma GCC diagnostic pop
+#endif
+#endif
+}
+}
+#endif