gecko-dev/mfbt/NullPtr.h
2013-01-21 19:42:15 -08:00

49 lines
1.3 KiB
C++

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* 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 workaround for compilers which do not support the C++11 nullptr
* constant.
*/
#ifndef mozilla_NullPtr_h_
#define mozilla_NullPtr_h_
#include "mozilla/Compiler.h"
#if defined(__clang__)
# ifndef __has_extension
# define __has_extension __has_feature
# endif
# if __has_extension(cxx_nullptr)
# define MOZ_HAVE_CXX11_NULLPTR
# endif
#elif defined(__GNUC__)
# if defined(__GXX_EXPERIMENTAL_CXX0X__) || __cplusplus >= 201103L
# if MOZ_GCC_VERSION_AT_LEAST(4, 6, 0)
# define MOZ_HAVE_CXX11_NULLPTR
# endif
# endif
#elif _MSC_VER >= 1600
# define MOZ_HAVE_CXX11_NULLPTR
#endif
/**
* Use C++11 nullptr if available; otherwise use __null for gcc, or a 0 literal
* with the correct size to match the size of a pointer on a given platform.
*/
#ifndef MOZ_HAVE_CXX11_NULLPTR
# if defined(__GNUC__)
# define nullptr __null
# elif defined(_WIN64)
# define nullptr 0LL
# else
# define nullptr 0L
# endif
#endif
#endif /* mozilla_NullPtr_h_ */