1// Pointer Traits -*- C++ -*-
2
3// Copyright (C) 2011-2015 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
37namespace 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