libMesh
libmesh_nullptr.h
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1 // The libMesh Finite Element Library.
2 // Copyright (C) 2002-2017 Benjamin S. Kirk, John W. Peterson, Roy H. Stogner
3 
4 // This library is free software; you can redistribute it and/or
5 // modify it under the terms of the GNU Lesser General Public
6 // License as published by the Free Software Foundation; either
7 // version 2.1 of the License, or (at your option) any later version.
8 
9 // This library is distributed in the hope that it will be useful,
10 // but WITHOUT ANY WARRANTY; without even the implied warranty of
11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 // Lesser General Public License for more details.
13 
14 // You should have received a copy of the GNU Lesser General Public
15 // License along with this library; if not, write to the Free Software
16 // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
17 
18 #ifndef LIBMESH_NULLPTR_H
19 #define LIBMESH_NULLPTR_H
20 
21 #include "libmesh/libmesh_config.h"
22 
23 #if defined(LIBMESH_HAVE_CXX11_NULLPTR)
24 
25 // Use the built-in nullptr keyword
26 #define libmesh_nullptr nullptr
27 
28 #elif defined(LIBMESH_HAVE_CXX11_NULLPTR_WORKAROUND)
29 
53 const class libmesh_nullptr_t
54 {
55 public:
56  // convertible to any type of null non-member pointer...
57  template<class T>
58  inline operator T * () const { return 0; }
59 
60  // or any type of null member pointer...
61  template<class C, class T>
62  inline operator T C::*() const { return 0; }
63 
64 private:
65  // Can't take address of nullptr
66  void operator & () const;
67 } libmesh_nullptr = {};
68 
69 #else
70 
71 // No nullptr and workaround doesn't compile. This should not be
72 // common, but in this case, We have to fall back on the C++03
73 // definition of NULL.
74 #define libmesh_nullptr NULL
75 
76 #endif // LIBMESH_HAVE_CXX11_NULLPTR
77 
78 #endif // LIBMESH_NULLPTR_H
const class libmesh_nullptr_t libmesh_nullptr
A C++03-compatible nullptr type implemented as a library solution rather than a language keyword...
void operator&() const