1 // Pointer Traits -*- C++ -*-
3 // Copyright (C) 2011-2014 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 #if __cplusplus >= 201103L
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
>
76 static constexpr true_type
77 _S_chk(typename
_Ptr2::template rebind
<_Up2
>*);
79 template<typename
, typename
>
80 static constexpr false_type
84 using __type
= decltype(_S_chk
<_Ptr
, _Up
>(nullptr));
87 template<typename _Tp
, typename _Up
,
88 bool = __ptrtr_rebind_helper
<_Tp
, _Up
>::__type::value
>
89 struct __ptrtr_rebind
;
91 template<typename _Tp
, typename _Up
>
92 struct __ptrtr_rebind
<_Tp
, _Up
, true>
94 typedef typename
_Tp::template rebind
<_Up
> __type
;
97 template<template<typename
, typename
...> class _SomePtr
, typename _Up
,
98 typename _Tp
, typename
... _Args
>
99 struct __ptrtr_rebind
<_SomePtr
<_Tp
, _Args
...>, _Up
, false>
101 typedef _SomePtr
<_Up
, _Args
...> __type
;
104 template<typename _Tp
, typename
= typename remove_cv
<_Tp
>::type
>
105 struct __ptrtr_not_void
110 template<typename _Tp
>
111 struct __ptrtr_not_void
<_Tp
, void>
116 template<typename _Ptr
>
117 class __ptrtr_pointer_to
119 typedef typename __ptrtr_elt_type
<_Ptr
>::__type __orig_type
;
120 typedef typename __ptrtr_not_void
<__orig_type
>::__type __element_type
;
123 static _Ptr
pointer_to(__element_type
& __e
)
124 { return _Ptr::pointer_to(__e
); }
128 * @brief Uniform interface to all pointer-like types
129 * @ingroup pointer_abstractions
131 template<typename _Ptr
>
132 struct pointer_traits
: __ptrtr_pointer_to
<_Ptr
>
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
;
141 template<typename _Up
>
142 using rebind
= typename __ptrtr_rebind
<_Ptr
, _Up
>::__type
;
146 * @brief Partial specialization for built-in pointers.
147 * @ingroup pointer_abstractions
149 template<typename _Tp
>
150 struct pointer_traits
<_Tp
*>
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
;
159 template<typename _Up
>
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)
168 pointer_to(typename __ptrtr_not_void
<element_type
>::__type
& __r
) noexcept
169 { return std::addressof(__r
); }
172 _GLIBCXX_END_NAMESPACE_VERSION