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