1 // Pointer Traits -*- C++ -*-
3 // Copyright (C) 2011 Free Software Foundation, Inc.
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)
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.
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.
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/>.
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}
31 #define _PTR_TRAITS_H 1
33 #ifdef __GXX_EXPERIMENTAL_CXX0X__
35 #include <type_traits> // For _GLIBCXX_HAS_NESTED_TYPE
37 namespace std _GLIBCXX_VISIBILITY(default)
39 _GLIBCXX_BEGIN_NAMESPACE_VERSION
41 _GLIBCXX_HAS_NESTED_TYPE(element_type)
42 _GLIBCXX_HAS_NESTED_TYPE(difference_type)
44 template<typename _Tp, bool = __has_element_type<_Tp>::value>
45 struct __ptrtr_elt_type;
47 template<typename _Tp>
48 struct __ptrtr_elt_type<_Tp, true>
50 typedef typename _Tp::element_type __type;
53 template<template<typename, typename...> class _SomePtr, typename _Tp,
55 struct __ptrtr_elt_type<_SomePtr<_Tp, _Args...>, false>
60 template<typename _Tp, bool = __has_difference_type<_Tp>::value>
61 struct __ptrtr_diff_type
63 typedef typename _Tp::difference_type __type;
66 template<typename _Tp>
67 struct __ptrtr_diff_type<_Tp, false>
69 typedef ptrdiff_t __type;
72 template<typename _Ptr, typename _Up>
73 class __ptrtr_rebind_helper
75 template<typename _Ptr2, typename _Up2>
77 _S_chk(typename _Ptr2::template rebind<_Up2>*)
80 template<typename, typename>
86 static const bool __value = _S_chk<_Ptr, _Up>(nullptr);
89 template<typename _Tp, typename _Up,
90 bool = __ptrtr_rebind_helper<_Tp, _Up>::__value>
91 struct __ptrtr_rebind;
93 template<typename _Tp, typename _Up>
94 struct __ptrtr_rebind<_Tp, _Up, true>
96 typedef typename _Tp::template rebind<_Up> __type;
99 template<template<typename, typename...> class _SomePtr, typename _Up,
100 typename _Tp, typename... _Args>
101 struct __ptrtr_rebind<_SomePtr<_Tp, _Args...>, _Up, false>
103 typedef _SomePtr<_Up, _Args...> __type;
106 template<typename _Tp, typename = typename remove_cv<_Tp>::type>
107 struct __ptrtr_not_void
112 template<typename _Tp>
113 struct __ptrtr_not_void<_Tp, void>
118 template<typename _Ptr>
119 class __ptrtr_pointer_to
121 typedef typename __ptrtr_elt_type<_Ptr>::__type __orig_type;
122 typedef typename __ptrtr_not_void<__orig_type>::__type __element_type;
125 static _Ptr pointer_to(__element_type& __e)
126 { return _Ptr::pointer_to(__e); }
130 * @brief Uniform interface to all pointer-like types
131 * @ingroup pointer_abstractions
133 template<typename _Ptr>
134 struct pointer_traits : __ptrtr_pointer_to<_Ptr>
137 typedef _Ptr pointer;
138 /// The type pointed to
139 typedef typename __ptrtr_elt_type<_Ptr>::__type element_type;
140 /// Type used to represent the difference between two pointers
141 typedef typename __ptrtr_diff_type<_Ptr>::__type difference_type;
143 template<typename _Up>
144 using rebind = typename __ptrtr_rebind<_Ptr, _Up>::__type;
148 * @brief Partial specialization for built-in pointers.
149 * @ingroup pointer_abstractions
151 template<typename _Tp>
152 struct pointer_traits<_Tp*>
155 typedef _Tp* pointer;
156 /// The type pointed to
157 typedef _Tp element_type;
158 /// Type used to represent the difference between two pointers
159 typedef ptrdiff_t difference_type;
161 template<typename _Up>
165 * @brief Obtain a pointer to an object
166 * @param __r A reference to an object of type @c element_type
167 * @return @c addressof(__r)
170 pointer_to(typename __ptrtr_not_void<element_type>::__type& __r) noexcept
171 { return std::addressof(__r); }
174 _GLIBCXX_END_NAMESPACE_VERSION