csutil/nullptr.h
00001 /* 00002 Copyright (C) 2010 by Mike Gist 00003 00004 This library is free software; you can redistribute it and/or 00005 modify it under the terms of the GNU Library General Public 00006 License as published by the Free Software Foundation; either 00007 version 2 of the License, or (at your option) any later version. 00008 00009 This library is distributed in the hope that it will be useful, 00010 but WITHOUT ANY WARRANTY; without even the implied warranty of 00011 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 00012 Library General Public License for more details. 00013 00014 You should have received a copy of the GNU Library General Public 00015 License along with this library; if not, write to the Free 00016 Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. 00017 */ 00018 00019 #ifndef __CSUTIL_NULLPTR_H__ 00020 #define __CSUTIL_NULLPTR_H__ 00021 00022 #if !defined(CS_NO_PROVIDE_NULLPTR) 00023 #if !defined(CS_HAS_NULLPTR) \ 00024 || (defined(__STRICT_ANSI__) && !defined(CS_HAS_NULLPTR_STRICT_ANSI)) 00025 00026 /* 00027 Based on "library implementation" in C++ Standards Committee paper 2431 00028 http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2431.pdf 00029 */ 00030 namespace std 00031 { 00032 class nullptr_t 00033 { 00034 private: 00035 void operator&() const; 00036 00037 public: 00038 template<typename T> 00039 operator T*() const 00040 { 00041 return 0; 00042 } 00043 00044 template<class C, typename T> 00045 operator T C::*() const 00046 { 00047 return 0; 00048 } 00049 }; 00050 } 00051 00052 #ifndef CS_NO_NULLPTR_RENAME_HACK 00053 /* Hack around the “identifier ‘nullptr’ will become a keyword in C++0x” 00054 * warnings gcc 4.6 emits. 00055 * The “proper” way – using a #pragma GCC diagnostic – is, unfortunately, 00056 * broken: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48914 00057 * Instead, to avoid use of that identifier, rename that identifier. 00058 */ 00059 #define nullptr CS_nullptr 00060 #endif 00061 00062 using ::std::nullptr_t; 00063 const nullptr_t nullptr = {}; 00064 00065 #endif /* !defined(CS_HAS_NULLPTR) \ 00066 || (defined(__STRICT_ANSI__) && !defined(CS_HAS_NULLPTR_STRICT_ANSI)) */ 00067 #endif // !defined(CS_NO_PROVIDE_NULLPTR) 00068 00069 #endif // __CSUTIL_NULLPTR_H__
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