1 files changed, 31 insertions, 0 deletions
diff --git a/mfbt/NullPtr.h b/mfbt/NullPtr.h
new file mode 100644
index 0000000000..d2248f4bcc
--- /dev/null
+++ b/mfbt/NullPtr.h
@@ -0,0 +1,31 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Implements a mozilla::IsNullPointer<T> type trait. */
+
+#ifndef mozilla_NullPtr_h
+#define mozilla_NullPtr_h
+
+#include "mozilla/TypeTraits.h"
+
+namespace mozilla {
+
+/**
+ * IsNullPointer<T>::value is true iff T is decltype(nullptr).
+ *
+ * Ideally this would be in TypeTraits.h, but C++11 omitted std::is_null_pointer
+ * (fixed in C++14), so in the interests of easing a switch to <type_traits>,
+ * this trait lives elsewhere.
+ */
+template<typename T>
+struct IsNullPointer : FalseType {};
+
+template<>
+struct IsNullPointer<decltype(nullptr)> : TrueType {};
+
+} // namespace mozilla
+
+#endif /* mozilla_NullPtr_h */