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The C and C++ Include Header Files
/usr/include/c++/11/bits/stl_tempbuf.h
$ cat -n /usr/include/c++/11/bits/stl_tempbuf.h 1 // Temporary buffer implementation -*- C++ -*- 2 3 // Copyright (C) 2001-2021 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 /* 26 * 27 * Copyright (c) 1994 28 * Hewlett-Packard Company 29 * 30 * Permission to use, copy, modify, distribute and sell this software 31 * and its documentation for any purpose is hereby granted without fee, 32 * provided that the above copyright notice appear in all copies and 33 * that both that copyright notice and this permission notice appear 34 * in supporting documentation. Hewlett-Packard Company makes no 35 * representations about the suitability of this software for any 36 * purpose. It is provided "as is" without express or implied warranty. 37 * 38 * 39 * Copyright (c) 1996,1997 40 * Silicon Graphics Computer Systems, Inc. 41 * 42 * Permission to use, copy, modify, distribute and sell this software 43 * and its documentation for any purpose is hereby granted without fee, 44 * provided that the above copyright notice appear in all copies and 45 * that both that copyright notice and this permission notice appear 46 * in supporting documentation. Silicon Graphics makes no 47 * representations about the suitability of this software for any 48 * purpose. It is provided "as is" without express or implied warranty. 49 */ 50 51 /** @file bits/stl_tempbuf.h 52 * This is an internal header file, included by other library headers. 53 * Do not attempt to use it directly. @headername{memory} 54 */ 55 56 #ifndef _STL_TEMPBUF_H 57 #define _STL_TEMPBUF_H 1 58 59 #include <bits/stl_algobase.h> 60 #include <bits/stl_construct.h> 61 62 namespace std _GLIBCXX_VISIBILITY(default) 63 { 64 _GLIBCXX_BEGIN_NAMESPACE_VERSION 65 66 namespace __detail 67 { 68 template<typename _Tp> 69 inline void 70 __return_temporary_buffer(_Tp* __p, 71 size_t __len __attribute__((__unused__))) 72 { 73 #if __cpp_sized_deallocation 74 ::operator delete(__p, __len * sizeof(_Tp)); 75 #else 76 ::operator delete(__p); 77 #endif 78 } 79 } 80 81 /** 82 * @brief Allocates a temporary buffer. 83 * @param __len The number of objects of type Tp. 84 * @return See full description. 85 * 86 * Reinventing the wheel, but this time with prettier spokes! 87 * 88 * This function tries to obtain storage for @c __len adjacent Tp 89 * objects. The objects themselves are not constructed, of course. 90 * A pair<> is returned containing <em>the buffer s address and 91 * capacity (in the units of sizeof(_Tp)), or a pair of 0 values if 92 * no storage can be obtained.</em> Note that the capacity obtained 93 * may be less than that requested if the memory is unavailable; 94 * you should compare len with the .second return value. 95 * 96 * Provides the nothrow exception guarantee. 97 */ 98 template<typename _Tp> 99 pair<_Tp*, ptrdiff_t> 100 get_temporary_buffer(ptrdiff_t __len) _GLIBCXX_NOEXCEPT 101 { 102 const ptrdiff_t __max = 103 __gnu_cxx::__numeric_traits<ptrdiff_t>::__max / sizeof(_Tp); 104 if (__len > __max) 105 __len = __max; 106 107 while (__len > 0) 108 { 109 _Tp* __tmp = static_cast<_Tp*>(::operator new(__len * sizeof(_Tp), 110 std::nothrow)); 111 if (__tmp != 0) 112 return std::pair<_Tp*, ptrdiff_t>(__tmp, __len); 113 __len = __len == 1 ? 0 : ((__len + 1) / 2); 114 } 115 return std::pair<_Tp*, ptrdiff_t>(static_cast<_Tp*>(0), 0); 116 } 117 118 /** 119 * @brief The companion to get_temporary_buffer(). 120 * @param __p A buffer previously allocated by get_temporary_buffer. 121 * @return None. 122 * 123 * Frees the memory pointed to by __p. 124 */ 125 template<typename _Tp> 126 inline void 127 return_temporary_buffer(_Tp* __p) 128 { ::operator delete(__p); } 129 130 /** 131 * This class is used in two places: stl_algo.h and ext/memory, 132 * where it is wrapped as the temporary_buffer class. See 133 * temporary_buffer docs for more notes. 134 */ 135 template<typename _ForwardIterator, typename _Tp> 136 class _Temporary_buffer 137 { 138 // concept requirements 139 __glibcxx_class_requires(_ForwardIterator, _ForwardIteratorConcept) 140 141 public: 142 typedef _Tp value_type; 143 typedef value_type* pointer; 144 typedef pointer iterator; 145 typedef ptrdiff_t size_type; 146 147 protected: 148 size_type _M_original_len; 149 size_type _M_len; 150 pointer _M_buffer; 151 152 public: 153 /// As per Table mumble. 154 size_type 155 size() const 156 { return _M_len; } 157 158 /// Returns the size requested by the constructor; may be >size(). 159 size_type 160 requested_size() const 161 { return _M_original_len; } 162 163 /// As per Table mumble. 164 iterator 165 begin() 166 { return _M_buffer; } 167 168 /// As per Table mumble. 169 iterator 170 end() 171 { return _M_buffer + _M_len; } 172 173 /** 174 * Constructs a temporary buffer of a size somewhere between 175 * zero and the given length. 176 */ 177 _Temporary_buffer(_ForwardIterator __seed, size_type __original_len); 178 179 ~_Temporary_buffer() 180 { 181 std::_Destroy(_M_buffer, _M_buffer + _M_len); 182 std::__detail::__return_temporary_buffer(_M_buffer, _M_len); 183 } 184 185 private: 186 // Disable copy constructor and assignment operator. 187 _Temporary_buffer(const _Temporary_buffer&); 188 189 void 190 operator=(const _Temporary_buffer&); 191 }; 192 193 194 template<bool> 195 struct __uninitialized_construct_buf_dispatch 196 { 197 template<typename _Pointer, typename _ForwardIterator> 198 static void 199 __ucr(_Pointer __first, _Pointer __last, 200 _ForwardIterator __seed) 201 { 202 if (__first == __last) 203 return; 204 205 _Pointer __cur = __first; 206 __try 207 { 208 std::_Construct(std::__addressof(*__first), 209 _GLIBCXX_MOVE(*__seed)); 210 _Pointer __prev = __cur; 211 ++__cur; 212 for(; __cur != __last; ++__cur, ++__prev) 213 std::_Construct(std::__addressof(*__cur), 214 _GLIBCXX_MOVE(*__prev)); 215 *__seed = _GLIBCXX_MOVE(*__prev); 216 } 217 __catch(...) 218 { 219 std::_Destroy(__first, __cur); 220 __throw_exception_again; 221 } 222 } 223 }; 224 225 template<> 226 struct __uninitialized_construct_buf_dispatch<true> 227 { 228 template<typename _Pointer, typename _ForwardIterator> 229 static void 230 __ucr(_Pointer, _Pointer, _ForwardIterator) { } 231 }; 232 233 // Constructs objects in the range [first, last). 234 // Note that while these new objects will take valid values, 235 // their exact value is not defined. In particular they may 236 // be 'moved from'. 237 // 238 // While *__seed may be altered during this algorithm, it will have 239 // the same value when the algorithm finishes, unless one of the 240 // constructions throws. 241 // 242 // Requirements: _Pointer::value_type(_Tp&&) is valid. 243 template<typename _Pointer, typename _ForwardIterator> 244 inline void 245 __uninitialized_construct_buf(_Pointer __first, _Pointer __last, 246 _ForwardIterator __seed) 247 { 248 typedef typename std::iterator_traits<_Pointer>::value_type 249 _ValueType; 250 251 std::__uninitialized_construct_buf_dispatch< 252 __has_trivial_constructor(_ValueType)>:: 253 __ucr(__first, __last, __seed); 254 } 255 256 template<typename _ForwardIterator, typename _Tp> 257 _Temporary_buffer<_ForwardIterator, _Tp>:: 258 _Temporary_buffer(_ForwardIterator __seed, size_type __original_len) 259 : _M_original_len(__original_len), _M_len(0), _M_buffer(0) 260 { 261 std::pair<pointer, size_type> __p( 262 std::get_temporary_buffer<value_type>(_M_original_len)); 263 264 if (__p.first) 265 { 266 __try 267 { 268 std::__uninitialized_construct_buf(__p.first, __p.first + __p.second, 269 __seed); 270 _M_buffer = __p.first; 271 _M_len = __p.second; 272 } 273 __catch(...) 274 { 275 std::__detail::__return_temporary_buffer(__p.first, __p.second); 276 __throw_exception_again; 277 } 278 } 279 } 280 281 _GLIBCXX_END_NAMESPACE_VERSION 282 } // namespace 283 284 #endif /* _STL_TEMPBUF_H */
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