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 /*
   8  * Implements a workaround for compilers which do not support the C++11 nullptr
   9  * constant.
  10  */
  11
  12 #ifndef mozilla_NullPtr_h
  13 #define mozilla_NullPtr_h
  14
  15 #if defined(__clang__)
  16 #  ifndef __has_extension
  17 #    define __has_extension __has_feature
  18 #  endif
  19 #  if __has_extension(cxx_nullptr)
  20 #    define MOZ_HAVE_CXX11_NULLPTR
  21 #  endif
  22 #elif defined(__GNUC__)
  23 #  if defined(__GXX_EXPERIMENTAL_CXX0X__) || __cplusplus >= 201103L
  24 #    include "mozilla/Compiler.h"
  25 #    if MOZ_GCC_VERSION_AT_LEAST(4, 6, 0)
  26 #      define MOZ_HAVE_CXX11_NULLPTR
  27 #    endif
  28 #  endif
  29 #elif _MSC_VER >= 1600
  30 # define MOZ_HAVE_CXX11_NULLPTR
  31 #endif
  32
  33 /**
  34  * Use C++11 nullptr if available; otherwise use __null for gcc, or a 0 literal
  35  * with the correct size to match the size of a pointer on a given platform.
  36  */
  37
  38 #ifndef MOZ_HAVE_CXX11_NULLPTR
  39 #  if defined(__GNUC__)
  40 #    define nullptr __null
  41 #  elif defined(_WIN64)
  42 #    define nullptr 0LL
  43 #  else
  44 #    define nullptr 0L
  45 #  endif
  46 #endif
  47
  48 #endif /* mozilla_NullPtr_h */