libstdc++
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00001 // Pointer Traits -*- C++ -*- 00002 00003 // Copyright (C) 2011 Free Software Foundation, Inc. 00004 // 00005 // This file is part of the GNU ISO C++ Library. This library is free 00006 // software; you can redistribute it and/or modify it under the 00007 // terms of the GNU General Public License as published by the 00008 // Free Software Foundation; either version 3, or (at your option) 00009 // any later version. 00010 00011 // This library is distributed in the hope that it will be useful, 00012 // but WITHOUT ANY WARRANTY; without even the implied warranty of 00013 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 00014 // GNU General Public License for more details. 00015 00016 // Under Section 7 of GPL version 3, you are granted additional 00017 // permissions described in the GCC Runtime Library Exception, version 00018 // 3.1, as published by the Free Software Foundation. 00019 00020 // You should have received a copy of the GNU General Public License and 00021 // a copy of the GCC Runtime Library Exception along with this program; 00022 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 00023 // <http://www.gnu.org/licenses/>. 00024 00025 /** @file bits/ptr_traits.h 00026 * This is an internal header file, included by other library headers. 00027 * Do not attempt to use it directly. @headername{memory} 00028 */ 00029 00030 #ifndef _PTR_TRAITS_H 00031 #define _PTR_TRAITS_H 1 00032 00033 #ifdef __GXX_EXPERIMENTAL_CXX0X__ 00034 00035 #include <type_traits> // For _GLIBCXX_HAS_NESTED_TYPE 00036 00037 namespace std _GLIBCXX_VISIBILITY(default) 00038 { 00039 _GLIBCXX_BEGIN_NAMESPACE_VERSION 00040 00041 _GLIBCXX_HAS_NESTED_TYPE(element_type) 00042 _GLIBCXX_HAS_NESTED_TYPE(difference_type) 00043 00044 template<typename _Tp, bool = __has_element_type<_Tp>::value> 00045 struct __ptrtr_elt_type; 00046 00047 template<typename _Tp> 00048 struct __ptrtr_elt_type<_Tp, true> 00049 { 00050 typedef typename _Tp::element_type __type; 00051 }; 00052 00053 template<template<typename, typename...> class _SomePtr, typename _Tp, 00054 typename... _Args> 00055 struct __ptrtr_elt_type<_SomePtr<_Tp, _Args...>, false> 00056 { 00057 typedef _Tp __type; 00058 }; 00059 00060 template<typename _Tp, bool = __has_difference_type<_Tp>::value> 00061 struct __ptrtr_diff_type 00062 { 00063 typedef typename _Tp::difference_type __type; 00064 }; 00065 00066 template<typename _Tp> 00067 struct __ptrtr_diff_type<_Tp, false> 00068 { 00069 typedef ptrdiff_t __type; 00070 }; 00071 00072 template<typename _Ptr, typename _Up> 00073 class __ptrtr_rebind_helper 00074 { 00075 template<typename _Ptr2, typename _Up2> 00076 static constexpr bool 00077 _S_chk(typename _Ptr2::template rebind<_Up2>*) 00078 { return true; } 00079 00080 template<typename, typename> 00081 static constexpr bool 00082 _S_chk(...) 00083 { return false; } 00084 00085 public: 00086 static const bool __value = _S_chk<_Ptr, _Up>(nullptr); 00087 }; 00088 00089 template<typename _Tp, typename _Up, 00090 bool = __ptrtr_rebind_helper<_Tp, _Up>::__value> 00091 struct __ptrtr_rebind; 00092 00093 template<typename _Tp, typename _Up> 00094 struct __ptrtr_rebind<_Tp, _Up, true> 00095 { 00096 typedef typename _Tp::template rebind<_Up> __type; 00097 }; 00098 00099 template<template<typename, typename...> class _SomePtr, typename _Up, 00100 typename _Tp, typename... _Args> 00101 struct __ptrtr_rebind<_SomePtr<_Tp, _Args...>, _Up, false> 00102 { 00103 typedef _SomePtr<_Up, _Args...> __type; 00104 }; 00105 00106 template<typename _Tp, typename = typename remove_cv<_Tp>::type> 00107 struct __ptrtr_not_void 00108 { 00109 typedef _Tp __type; 00110 }; 00111 00112 template<typename _Tp> 00113 struct __ptrtr_not_void<_Tp, void> 00114 { 00115 struct __type { }; 00116 }; 00117 00118 template<typename _Ptr> 00119 class __ptrtr_pointer_to 00120 { 00121 typedef typename __ptrtr_elt_type<_Ptr>::__type __orig_type; 00122 typedef typename __ptrtr_not_void<__orig_type>::__type __element_type; 00123 00124 public: 00125 static _Ptr pointer_to(__element_type& __e) 00126 { return _Ptr::pointer_to(__e); } 00127 }; 00128 00129 /** 00130 * @brief Uniform interface to all pointer-like types 00131 * @ingroup pointer_abstractions 00132 */ 00133 template<typename _Ptr> 00134 struct pointer_traits : __ptrtr_pointer_to<_Ptr> 00135 { 00136 /// The pointer type 00137 typedef _Ptr pointer; 00138 /// The type pointed to 00139 typedef typename __ptrtr_elt_type<_Ptr>::__type element_type; 00140 /// Type used to represent the difference between two pointers 00141 typedef typename __ptrtr_diff_type<_Ptr>::__type difference_type; 00142 00143 private: 00144 template<typename _Up> 00145 using rebind = typename __ptrtr_rebind<_Ptr, _Up>::__type; 00146 00147 // allocator_traits needs to use __rebind 00148 template<typename> friend struct allocator_traits; 00149 template<typename> friend struct pointer_traits; 00150 template<typename, typename> friend class __ptrtr_rebind_helper2; 00151 }; 00152 00153 /** 00154 * @brief Partial specialization for built-in pointers. 00155 * @ingroup pointer_abstractions 00156 */ 00157 template<typename _Tp> 00158 struct pointer_traits<_Tp*> 00159 { 00160 /// The pointer type 00161 typedef _Tp* pointer; 00162 /// The type pointed to 00163 typedef _Tp element_type; 00164 /// Type used to represent the difference between two pointers 00165 typedef ptrdiff_t difference_type; 00166 00167 template<typename _Up> 00168 using rebind = _Up*; 00169 00170 /** 00171 * @brief Obtain a pointer to an object 00172 * @param __r A reference to an object of type @c element_type 00173 * @return @c addressof(__r) 00174 */ 00175 static pointer 00176 pointer_to(typename __ptrtr_not_void<element_type>::__type& __r) noexcept 00177 { return std::addressof(__r); } 00178 }; 00179 00180 _GLIBCXX_END_NAMESPACE_VERSION 00181 } // namespace std 00182 00183 #endif 00184 00185 #endif