1 // Temporary buffer implementation -*- C++ -*- 2 3 // Copyright (C) 2001-2013 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 /* 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 /** 67 * @brief Allocates a temporary buffer. 68 * @param __len The number of objects of type Tp. 69 * @return See full description. 70 * 71 * Reinventing the wheel, but this time with prettier spokes! 72 * 73 * This function tries to obtain storage for @c __len adjacent Tp 74 * objects. The objects themselves are not constructed, of course. 75 * A pair<> is returned containing <em>the buffer s address and 76 * capacity (in the units of sizeof(_Tp)), or a pair of 0 values if 77 * no storage can be obtained.</em> Note that the capacity obtained 78 * may be less than that requested if the memory is unavailable; 79 * you should compare len with the .second return value. 80 * 81 * Provides the nothrow exception guarantee. 82 */ 83 template<typename _Tp> 84 pair<_Tp*, ptrdiff_t> 85 get_temporary_buffer(ptrdiff_t __len) _GLIBCXX_NOEXCEPT 86 { 87 const ptrdiff_t __max = 88 __gnu_cxx::__numeric_traits<ptrdiff_t>::__max / sizeof(_Tp); 89 if (__len > __max) 90 __len = __max; 91 92 while (__len > 0) 93 { 94 _Tp* __tmp = static_cast<_Tp*>(::operator new(__len * sizeof(_Tp), 95 std::nothrow)); 96 if (__tmp != 0) 97 return std::pair<_Tp*, ptrdiff_t>(__tmp, __len); 98 __len /= 2; 99 } 100 return std::pair<_Tp*, ptrdiff_t>(static_cast<_Tp*>(0), 0); 101 } 102 103 /** 104 * @brief The companion to get_temporary_buffer(). 105 * @param __p A buffer previously allocated by get_temporary_buffer. 106 * @return None. 107 * 108 * Frees the memory pointed to by __p. 109 */ 110 template<typename _Tp> 111 inline void 112 return_temporary_buffer(_Tp* __p) 113 { ::operator delete(__p, std::nothrow); } 114 115 116 /** 117 * This class is used in two places: stl_algo.h and ext/memory, 118 * where it is wrapped as the temporary_buffer class. See 119 * temporary_buffer docs for more notes. 120 */ 121 template<typename _ForwardIterator, typename _Tp> 122 class _Temporary_buffer 123 { 124 // concept requirements 125 __glibcxx_class_requires(_ForwardIterator, _ForwardIteratorConcept) 126 127 public: 128 typedef _Tp value_type; 129 typedef value_type* pointer; 130 typedef pointer iterator; 131 typedef ptrdiff_t size_type; 132 133 protected: 134 size_type _M_original_len; 135 size_type _M_len; 136 pointer _M_buffer; 137 138 public: 139 /// As per Table mumble. 140 size_type 141 size() const 142 { return _M_len; } 143 144 /// Returns the size requested by the constructor; may be >size(). 145 size_type 146 requested_size() const 147 { return _M_original_len; } 148 149 /// As per Table mumble. 150 iterator 151 begin() 152 { return _M_buffer; } 153 154 /// As per Table mumble. 155 iterator 156 end() 157 { return _M_buffer + _M_len; } 158 159 /** 160 * Constructs a temporary buffer of a size somewhere between 161 * zero and the size of the given range. 162 */ 163 _Temporary_buffer(_ForwardIterator __first, _ForwardIterator __last); 164 165 ~_Temporary_buffer() 166 { 167 std::_Destroy(_M_buffer, _M_buffer + _M_len); 168 std::return_temporary_buffer(_M_buffer); 169 } 170 171 private: 172 // Disable copy constructor and assignment operator. 173 _Temporary_buffer(const _Temporary_buffer&); 174 175 void 176 operator=(const _Temporary_buffer&); 177 }; 178 179 180 template<bool> 181 struct __uninitialized_construct_buf_dispatch 182 { 183 template<typename _Pointer, typename _ForwardIterator> 184 static void 185 __ucr(_Pointer __first, _Pointer __last, 186 _ForwardIterator __seed) 187 { 188 if(__first == __last) 189 return; 190 191 _Pointer __cur = __first; 192 __try 193 { 194 std::_Construct(std::__addressof(*__first), 195 _GLIBCXX_MOVE(*__seed)); 196 _Pointer __prev = __cur; 197 ++__cur; 198 for(; __cur != __last; ++__cur, ++__prev) 199 std::_Construct(std::__addressof(*__cur), 200 _GLIBCXX_MOVE(*__prev)); 201 *__seed = _GLIBCXX_MOVE(*__prev); 202 } 203 __catch(...) 204 { 205 std::_Destroy(__first, __cur); 206 __throw_exception_again; 207 } 208 } 209 }; 210 211 template<> 212 struct __uninitialized_construct_buf_dispatch<true> 213 { 214 template<typename _Pointer, typename _ForwardIterator> 215 static void 216 __ucr(_Pointer, _Pointer, _ForwardIterator) { } 217 }; 218 219 // Constructs objects in the range [first, last). 220 // Note that while these new objects will take valid values, 221 // their exact value is not defined. In particular they may 222 // be 'moved from'. 223 // 224 // While *__seed may be altered during this algorithm, it will have 225 // the same value when the algorithm finishes, unless one of the 226 // constructions throws. 227 // 228 // Requirements: _Pointer::value_type(_Tp&&) is valid. 229 template<typename _Pointer, typename _ForwardIterator> 230 inline void 231 __uninitialized_construct_buf(_Pointer __first, _Pointer __last, 232 _ForwardIterator __seed) 233 { 234 typedef typename std::iterator_traits<_Pointer>::value_type 235 _ValueType; 236 237 std::__uninitialized_construct_buf_dispatch< 238 __has_trivial_constructor(_ValueType)>:: 239 __ucr(__first, __last, __seed); 240 } 241 242 template<typename _ForwardIterator, typename _Tp> 243 _Temporary_buffer<_ForwardIterator, _Tp>:: 244 _Temporary_buffer(_ForwardIterator __first, _ForwardIterator __last) 245 : _M_original_len(std::distance(__first, __last)), 246 _M_len(0), _M_buffer(0) 247 { 248 __try 249 { 250 std::pair<pointer, size_type> __p(std::get_temporary_buffer< 251 value_type>(_M_original_len)); 252 _M_buffer = __p.first; 253 _M_len = __p.second; 254 if (_M_buffer) 255 std::__uninitialized_construct_buf(_M_buffer, _M_buffer + _M_len, 256 __first); 257 } 258 __catch(...) 259 { 260 std::return_temporary_buffer(_M_buffer); 261 _M_buffer = 0; 262 _M_len = 0; 263 __throw_exception_again; 264 } 265 } 266 267 _GLIBCXX_END_NAMESPACE_VERSION 268 } // namespace 269 270 #endif /* _STL_TEMPBUF_H */ 271 272
