1/*
2
3Copyright (C) 2010 Apple Inc. All rights reserved.
4
5Redistribution and use in source and binary forms, with or without
6modification, are permitted provided that the following conditions
7are met:
81.  Redistributions of source code must retain the above copyright
9    notice, this list of conditions and the following disclaimer.
102.  Redistributions in binary form must reproduce the above copyright
11    notice, this list of conditions and the following disclaimer in the
12    documentation and/or other materials provided with the distribution.
13
14THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' AND ANY
15EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
16WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
17DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS BE LIABLE FOR ANY
18DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
19(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
20LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
21ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
23SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24
25*/
26
27#ifndef NullPtr_h
28#define NullPtr_h
29
30// For compilers and standard libraries that do not yet include it, this adds the
31// nullptr_t type and nullptr object. They are defined in the same namespaces they
32// would be in compiler and library that had the support.
33
34#if COMPILER_SUPPORTS(CXX_NULLPTR) || defined(_LIBCPP_VERSION)
35
36// libstdc++ supports nullptr_t starting with gcc 4.6. STLport doesn't define it.
37#if (defined(__GLIBCXX__) && __GLIBCXX__ < 20110325) || defined(_STLPORT_VERSION)
38namespace std {
39typedef decltype(nullptr) nullptr_t;
40}
41#endif
42
43#else
44
45#include "wtf/WTFExport.h"
46
47namespace std {
48class nullptr_t {
49public:
50    // Required in order to create const nullptr_t objects without an
51    // explicit initializer in GCC 4.5, a la:
52    //
53    // const std::nullptr_t nullptr;
54    nullptr_t() { }
55
56    // Make nullptr convertible to any pointer type.
57    template<typename T> operator T*() const { return 0; }
58    // Make nullptr convertible to any member pointer type.
59    template<typename C, typename T> operator T C::*() { return 0; }
60private:
61    // Do not allow taking the address of nullptr.
62    void operator&();
63};
64}
65WTF_EXPORT extern const std::nullptr_t nullptr;
66
67#endif
68
69#if COMPILER_SUPPORTS(CXX_DELETED_FUNCTIONS)
70#define WTF_DISALLOW_CONSTRUCTION_FROM_ZERO(ClassName) \
71    private: \
72        ClassName(int) = delete
73#define WTF_DISALLOW_ZERO_ASSIGNMENT(ClassName) \
74    private: \
75        ClassName& operator=(int) = delete
76#else
77#define WTF_DISALLOW_CONSTRUCTION_FROM_ZERO(ClassName) \
78    private: \
79        ClassName(int)
80#define WTF_DISALLOW_ZERO_ASSIGNMENT(ClassName) \
81    private: \
82        ClassName& operator=(int)
83#endif
84
85#endif
86