1// Pointer Traits -*- C++ -*-
2
3// Copyright (C) 2011-2013 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 bool
77       	_S_chk(typename _Ptr2::template rebind<_Up2>*)
78       	{ return true; }
79
80      template<typename, typename>
81        static constexpr bool
82       	_S_chk(...)
83       	{ return false; }
84
85    public:
86      static const bool __value = _S_chk<_Ptr, _Up>(nullptr);
87    };
88
89  template<typename _Ptr, typename _Up>
90    const bool __ptrtr_rebind_helper<_Ptr, _Up>::__value;
91
92  template<typename _Tp, typename _Up,
93           bool = __ptrtr_rebind_helper<_Tp, _Up>::__value>
94    struct __ptrtr_rebind;
95
96  template<typename _Tp, typename _Up>
97    struct __ptrtr_rebind<_Tp, _Up, true>
98    {
99      typedef typename _Tp::template rebind<_Up> __type;
100    };
101
102  template<template<typename, typename...> class _SomePtr, typename _Up,
103            typename _Tp, typename... _Args>
104    struct __ptrtr_rebind<_SomePtr<_Tp, _Args...>, _Up, false>
105    {
106      typedef _SomePtr<_Up, _Args...> __type;
107    };
108
109  template<typename _Tp, typename = typename remove_cv<_Tp>::type>
110    struct __ptrtr_not_void
111    {
112      typedef _Tp __type;
113    };
114
115  template<typename _Tp>
116    struct __ptrtr_not_void<_Tp, void>
117    {
118      struct __type { };
119    };
120
121  template<typename _Ptr>
122    class __ptrtr_pointer_to
123    {
124      typedef typename __ptrtr_elt_type<_Ptr>::__type   __orig_type;
125      typedef typename __ptrtr_not_void<__orig_type>::__type __element_type;
126
127    public:
128      static _Ptr pointer_to(__element_type& __e)
129      { return _Ptr::pointer_to(__e); }
130    };
131
132  /**
133   * @brief  Uniform interface to all pointer-like types
134   * @ingroup pointer_abstractions
135  */
136  template<typename _Ptr>
137    struct pointer_traits : __ptrtr_pointer_to<_Ptr>
138    {
139      /// The pointer type
140      typedef _Ptr                                      pointer;
141      /// The type pointed to
142      typedef typename __ptrtr_elt_type<_Ptr>::__type   element_type;
143      /// Type used to represent the difference between two pointers
144      typedef typename __ptrtr_diff_type<_Ptr>::__type  difference_type;
145
146      template<typename _Up>
147        using rebind = typename __ptrtr_rebind<_Ptr, _Up>::__type;
148    };
149
150  /**
151   * @brief  Partial specialization for built-in pointers.
152   * @ingroup pointer_abstractions
153  */
154  template<typename _Tp>
155    struct pointer_traits<_Tp*>
156    {
157      /// The pointer type
158      typedef _Tp* pointer;
159      /// The type pointed to
160      typedef _Tp  element_type;
161      /// Type used to represent the difference between two pointers
162      typedef ptrdiff_t difference_type;
163
164      template<typename _Up>
165        using rebind = _Up*;
166
167      /**
168       *  @brief  Obtain a pointer to an object
169       *  @param  __r  A reference to an object of type @c element_type
170       *  @return @c addressof(__r)
171      */
172      static pointer
173      pointer_to(typename __ptrtr_not_void<element_type>::__type& __r) noexcept
174      { return std::addressof(__r); }
175    };
176
177_GLIBCXX_END_NAMESPACE_VERSION
178} // namespace std
179
180#endif
181
182#endif
183