mfbt/NullPtr.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 /* Implements a mozilla::IsNullPointer<T> type trait. */
   8
   9 #ifndef mozilla_NullPtr_h
  10 #define mozilla_NullPtr_h
  11
  12 #include "mozilla/TypeTraits.h"
  13
  14 namespace mozilla {
  15
  16 /**
  17  * IsNullPointer<T>::value is true iff T is decltype(nullptr).
  18  *
  19  * Ideally this would be in TypeTraits.h, but C++11 omitted std::is_null_pointer
  20  * (fixed in C++14), so in the interests of easing a switch to <type_traits>,
  21  * this trait lives elsewhere.
  22  */
  23 template<typename T>
  24 struct IsNullPointer : FalseType {};
  25
  26 template<>
  27 struct IsNullPointer<decltype(nullptr)> : TrueType {};
  28
  29 } // namespace mozilla
  30
  31 #endif /* mozilla_NullPtr_h */