1 | // Pointer Traits -*- C++ -*- |
2 | |
3 | // Copyright (C) 2011-2014 Free Software Foundation, Inc. |
4 | // |
5 | // This file is part of the GNU ISO C++ Library. This library is free |
6 | // software; you can redistribute it and/or modify it under the |
7 | // terms of the GNU General Public License as published by the |
8 | // Free Software Foundation; either version 3, or (at your option) |
9 | // any later version. |
10 | |
11 | // This library is distributed in the hope that it will be useful, |
12 | // but WITHOUT ANY WARRANTY; without even the implied warranty of |
13 | // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
14 | // GNU General Public License for more details. |
15 | |
16 | // Under Section 7 of GPL version 3, you are granted additional |
17 | // permissions described in the GCC Runtime Library Exception, version |
18 | // 3.1, as published by the Free Software Foundation. |
19 | |
20 | // You should have received a copy of the GNU General Public License and |
21 | // a copy of the GCC Runtime Library Exception along with this program; |
22 | // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see |
23 | // <http://www.gnu.org/licenses/>. |
24 | |
25 | /** @file bits/ptr_traits.h |
26 | * This is an internal header file, included by other library headers. |
27 | * Do not attempt to use it directly. @headername{memory} |
28 | */ |
29 | |
30 | #ifndef _PTR_TRAITS_H |
31 | #define _PTR_TRAITS_H 1 |
32 | |
33 | #if __cplusplus >= 201103L |
34 | |
35 | #include <type_traits> // For _GLIBCXX_HAS_NESTED_TYPE |
36 | |
37 | namespace std _GLIBCXX_VISIBILITY(default) |
38 | { |
39 | _GLIBCXX_BEGIN_NAMESPACE_VERSION |
40 | |
41 | _GLIBCXX_HAS_NESTED_TYPE(element_type) |
42 | _GLIBCXX_HAS_NESTED_TYPE(difference_type) |
43 | |
44 | template<typename _Tp, bool = __has_element_type<_Tp>::value> |
45 | struct __ptrtr_elt_type; |
46 | |
47 | template<typename _Tp> |
48 | struct __ptrtr_elt_type<_Tp, true> |
49 | { |
50 | typedef typename _Tp::element_type __type; |
51 | }; |
52 | |
53 | template<template<typename, typename...> class _SomePtr, typename _Tp, |
54 | typename... _Args> |
55 | struct __ptrtr_elt_type<_SomePtr<_Tp, _Args...>, false> |
56 | { |
57 | typedef _Tp __type; |
58 | }; |
59 | |
60 | template<typename _Tp, bool = __has_difference_type<_Tp>::value> |
61 | struct __ptrtr_diff_type |
62 | { |
63 | typedef typename _Tp::difference_type __type; |
64 | }; |
65 | |
66 | template<typename _Tp> |
67 | struct __ptrtr_diff_type<_Tp, false> |
68 | { |
69 | typedef ptrdiff_t __type; |
70 | }; |
71 | |
72 | template<typename _Ptr, typename _Up> |
73 | class __ptrtr_rebind_helper |
74 | { |
75 | template<typename _Ptr2, typename _Up2> |
76 | static constexpr true_type |
77 | _S_chk(typename _Ptr2::template rebind<_Up2>*); |
78 | |
79 | template<typename, typename> |
80 | static constexpr false_type |
81 | _S_chk(...); |
82 | |
83 | public: |
84 | using __type = decltype(_S_chk<_Ptr, _Up>(nullptr)); |
85 | }; |
86 | |
87 | template<typename _Tp, typename _Up, |
88 | bool = __ptrtr_rebind_helper<_Tp, _Up>::__type::value> |
89 | struct __ptrtr_rebind; |
90 | |
91 | template<typename _Tp, typename _Up> |
92 | struct __ptrtr_rebind<_Tp, _Up, true> |
93 | { |
94 | typedef typename _Tp::template rebind<_Up> __type; |
95 | }; |
96 | |
97 | template<template<typename, typename...> class _SomePtr, typename _Up, |
98 | typename _Tp, typename... _Args> |
99 | struct __ptrtr_rebind<_SomePtr<_Tp, _Args...>, _Up, false> |
100 | { |
101 | typedef _SomePtr<_Up, _Args...> __type; |
102 | }; |
103 | |
104 | template<typename _Tp, typename = typename remove_cv<_Tp>::type> |
105 | struct __ptrtr_not_void |
106 | { |
107 | typedef _Tp __type; |
108 | }; |
109 | |
110 | template<typename _Tp> |
111 | struct __ptrtr_not_void<_Tp, void> |
112 | { |
113 | struct __type { }; |
114 | }; |
115 | |
116 | template<typename _Ptr> |
117 | class __ptrtr_pointer_to |
118 | { |
119 | typedef typename __ptrtr_elt_type<_Ptr>::__type __orig_type; |
120 | typedef typename __ptrtr_not_void<__orig_type>::__type __element_type; |
121 | |
122 | public: |
123 | static _Ptr pointer_to(__element_type& __e) |
124 | { return _Ptr::pointer_to(__e); } |
125 | }; |
126 | |
127 | /** |
128 | * @brief Uniform interface to all pointer-like types |
129 | * @ingroup pointer_abstractions |
130 | */ |
131 | template<typename _Ptr> |
132 | struct pointer_traits : __ptrtr_pointer_to<_Ptr> |
133 | { |
134 | /// The pointer type |
135 | typedef _Ptr pointer; |
136 | /// The type pointed to |
137 | typedef typename __ptrtr_elt_type<_Ptr>::__type element_type; |
138 | /// Type used to represent the difference between two pointers |
139 | typedef typename __ptrtr_diff_type<_Ptr>::__type difference_type; |
140 | |
141 | template<typename _Up> |
142 | using rebind = typename __ptrtr_rebind<_Ptr, _Up>::__type; |
143 | }; |
144 | |
145 | /** |
146 | * @brief Partial specialization for built-in pointers. |
147 | * @ingroup pointer_abstractions |
148 | */ |
149 | template<typename _Tp> |
150 | struct pointer_traits<_Tp*> |
151 | { |
152 | /// The pointer type |
153 | typedef _Tp* pointer; |
154 | /// The type pointed to |
155 | typedef _Tp element_type; |
156 | /// Type used to represent the difference between two pointers |
157 | typedef ptrdiff_t difference_type; |
158 | |
159 | template<typename _Up> |
160 | using rebind = _Up*; |
161 | |
162 | /** |
163 | * @brief Obtain a pointer to an object |
164 | * @param __r A reference to an object of type @c element_type |
165 | * @return @c addressof(__r) |
166 | */ |
167 | static pointer |
168 | pointer_to(typename __ptrtr_not_void<element_type>::__type& __r) noexcept |
169 | { return std::addressof(__r); } |
170 | }; |
171 | |
172 | _GLIBCXX_END_NAMESPACE_VERSION |
173 | } // namespace std |
174 | |
175 | #endif |
176 | |
177 | #endif |
178 | |