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The C and C++ Include Header Files
/usr/include/c++/13/bits/stl_tempbuf.h
$ cat -n /usr/include/c++/13/bits/stl_tempbuf.h 1 // Temporary buffer implementation -*- C++ -*- 2 3 // Copyright (C) 2001-2023 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 <new> 60 #include <bits/exception_defines.h> 61 #include <bits/stl_construct.h> 62 #include <bits/stl_pair.h> 63 #include <ext/numeric_traits.h> 64 65 namespace std _GLIBCXX_VISIBILITY(default) 66 { 67 _GLIBCXX_BEGIN_NAMESPACE_VERSION 68 69 namespace __detail 70 { 71 template<typename _Tp> 72 inline void 73 __return_temporary_buffer(_Tp* __p, 74 size_t __len __attribute__((__unused__))) 75 { 76 #if __cpp_sized_deallocation 77 ::operator delete(__p, __len * sizeof(_Tp)); 78 #else 79 ::operator delete(__p); 80 #endif 81 } 82 } 83 84 /** 85 * @brief Allocates a temporary buffer. 86 * @param __len The number of objects of type Tp. 87 * @return See full description. 88 * 89 * Reinventing the wheel, but this time with prettier spokes! 90 * 91 * This function tries to obtain storage for @c __len adjacent Tp 92 * objects. The objects themselves are not constructed, of course. 93 * A pair<> is returned containing <em>the buffer s address and 94 * capacity (in the units of sizeof(_Tp)), or a pair of 0 values if 95 * no storage can be obtained.</em> Note that the capacity obtained 96 * may be less than that requested if the memory is unavailable; 97 * you should compare len with the .second return value. 98 * 99 * Provides the nothrow exception guarantee. 100 */ 101 template<typename _Tp> 102 _GLIBCXX17_DEPRECATED 103 pair<_Tp*, ptrdiff_t> 104 get_temporary_buffer(ptrdiff_t __len) _GLIBCXX_NOEXCEPT 105 { 106 const ptrdiff_t __max = 107 __gnu_cxx::__numeric_traits<ptrdiff_t>::__max / sizeof(_Tp); 108 if (__len > __max) 109 __len = __max; 110 111 while (__len > 0) 112 { 113 _Tp* __tmp = static_cast<_Tp*>(::operator new(__len * sizeof(_Tp), 114 std::nothrow)); 115 if (__tmp != 0) 116 return std::pair<_Tp*, ptrdiff_t>(__tmp, __len); 117 __len = __len == 1 ? 0 : ((__len + 1) / 2); 118 } 119 return std::pair<_Tp*, ptrdiff_t>(static_cast<_Tp*>(0), 0); 120 } 121 122 /** 123 * @brief The companion to get_temporary_buffer(). 124 * @param __p A buffer previously allocated by get_temporary_buffer. 125 * @return None. 126 * 127 * Frees the memory pointed to by __p. 128 */ 129 template<typename _Tp> 130 inline void 131 return_temporary_buffer(_Tp* __p) 132 { ::operator delete(__p); } 133 134 /** 135 * This class is used in two places: stl_algo.h and ext/memory, 136 * where it is wrapped as the temporary_buffer class. See 137 * temporary_buffer docs for more notes. 138 */ 139 template<typename _ForwardIterator, typename _Tp> 140 class _Temporary_buffer 141 { 142 // concept requirements 143 __glibcxx_class_requires(_ForwardIterator, _ForwardIteratorConcept) 144 145 public: 146 typedef _Tp value_type; 147 typedef value_type* pointer; 148 typedef pointer iterator; 149 typedef ptrdiff_t size_type; 150 151 protected: 152 size_type _M_original_len; 153 size_type _M_len; 154 pointer _M_buffer; 155 156 public: 157 /// As per Table mumble. 158 size_type 159 size() const 160 { return _M_len; } 161 162 /// Returns the size requested by the constructor; may be >size(). 163 size_type 164 requested_size() const 165 { return _M_original_len; } 166 167 /// As per Table mumble. 168 iterator 169 begin() 170 { return _M_buffer; } 171 172 /// As per Table mumble. 173 iterator 174 end() 175 { return _M_buffer + _M_len; } 176 177 /** 178 * Constructs a temporary buffer of a size somewhere between 179 * zero and the given length. 180 */ 181 _Temporary_buffer(_ForwardIterator __seed, size_type __original_len); 182 183 ~_Temporary_buffer() 184 { 185 std::_Destroy(_M_buffer, _M_buffer + _M_len); 186 std::__detail::__return_temporary_buffer(_M_buffer, _M_len); 187 } 188 189 private: 190 // Disable copy constructor and assignment operator. 191 _Temporary_buffer(const _Temporary_buffer&); 192 193 void 194 operator=(const _Temporary_buffer&); 195 }; 196 197 198 template<bool> 199 struct __uninitialized_construct_buf_dispatch 200 { 201 template<typename _Pointer, typename _ForwardIterator> 202 static void 203 __ucr(_Pointer __first, _Pointer __last, 204 _ForwardIterator __seed) 205 { 206 if (__first == __last) 207 return; 208 209 _Pointer __cur = __first; 210 __try 211 { 212 std::_Construct(std::__addressof(*__first), 213 _GLIBCXX_MOVE(*__seed)); 214 _Pointer __prev = __cur; 215 ++__cur; 216 for(; __cur != __last; ++__cur, ++__prev) 217 std::_Construct(std::__addressof(*__cur), 218 _GLIBCXX_MOVE(*__prev)); 219 *__seed = _GLIBCXX_MOVE(*__prev); 220 } 221 __catch(...) 222 { 223 std::_Destroy(__first, __cur); 224 __throw_exception_again; 225 } 226 } 227 }; 228 229 template<> 230 struct __uninitialized_construct_buf_dispatch<true> 231 { 232 template<typename _Pointer, typename _ForwardIterator> 233 static void 234 __ucr(_Pointer, _Pointer, _ForwardIterator) { } 235 }; 236 237 // Constructs objects in the range [first, last). 238 // Note that while these new objects will take valid values, 239 // their exact value is not defined. In particular they may 240 // be 'moved from'. 241 // 242 // While *__seed may be altered during this algorithm, it will have 243 // the same value when the algorithm finishes, unless one of the 244 // constructions throws. 245 // 246 // Requirements: _Pointer::value_type(_Tp&&) is valid. 247 template<typename _Pointer, typename _ForwardIterator> 248 inline void 249 __uninitialized_construct_buf(_Pointer __first, _Pointer __last, 250 _ForwardIterator __seed) 251 { 252 typedef typename std::iterator_traits<_Pointer>::value_type 253 _ValueType; 254 255 std::__uninitialized_construct_buf_dispatch< 256 __has_trivial_constructor(_ValueType)>:: 257 __ucr(__first, __last, __seed); 258 } 259 260 #pragma GCC diagnostic push 261 #pragma GCC diagnostic ignored "-Wdeprecated-declarations" 262 template<typename _ForwardIterator, typename _Tp> 263 _Temporary_buffer<_ForwardIterator, _Tp>:: 264 _Temporary_buffer(_ForwardIterator __seed, size_type __original_len) 265 : _M_original_len(__original_len), _M_len(0), _M_buffer(0) 266 { 267 std::pair<pointer, size_type> __p( 268 std::get_temporary_buffer<value_type>(_M_original_len)); 269 270 if (__p.first) 271 { 272 __try 273 { 274 std::__uninitialized_construct_buf(__p.first, __p.first + __p.second, 275 __seed); 276 _M_buffer = __p.first; 277 _M_len = __p.second; 278 } 279 __catch(...) 280 { 281 std::__detail::__return_temporary_buffer(__p.first, __p.second); 282 __throw_exception_again; 283 } 284 } 285 } 286 #pragma GCC diagnostic pop 287 288 _GLIBCXX_END_NAMESPACE_VERSION 289 } // namespace 290 291 #endif /* _STL_TEMPBUF_H */
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