1 // Temporary buffer implementation -*- C++ -*- 2 3 // Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010 4 // Free Software Foundation, Inc. 5 // 6 // This file is part of the GNU ISO C++ Library. This library is free 7 // software; you can redistribute it and/or modify it under the 8 // terms of the GNU General Public License as published by the 9 // Free Software Foundation; either version 3, or (at your option) 10 // any later version. 11 12 // This library is distributed in the hope that it will be useful, 13 // but WITHOUT ANY WARRANTY; without even the implied warranty of 14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15 // GNU General Public License for more details. 16 17 // Under Section 7 of GPL version 3, you are granted additional 18 // permissions described in the GCC Runtime Library Exception, version 19 // 3.1, as published by the Free Software Foundation. 20 21 // You should have received a copy of the GNU General Public License and 22 // a copy of the GCC Runtime Library Exception along with this program; 23 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 24 // <http://www.gnu.org/licenses/>. 25 26 /* 27 * 28 * Copyright (c) 1994 29 * Hewlett-Packard Company 30 * 31 * Permission to use, copy, modify, distribute and sell this software 32 * and its documentation for any purpose is hereby granted without fee, 33 * provided that the above copyright notice appear in all copies and 34 * that both that copyright notice and this permission notice appear 35 * in supporting documentation. Hewlett-Packard Company makes no 36 * representations about the suitability of this software for any 37 * purpose. It is provided "as is" without express or implied warranty. 38 * 39 * 40 * Copyright (c) 1996,1997 41 * Silicon Graphics Computer Systems, Inc. 42 * 43 * Permission to use, copy, modify, distribute and sell this software 44 * and its documentation for any purpose is hereby granted without fee, 45 * provided that the above copyright notice appear in all copies and 46 * that both that copyright notice and this permission notice appear 47 * in supporting documentation. Silicon Graphics makes no 48 * representations about the suitability of this software for any 49 * purpose. It is provided "as is" without express or implied warranty. 50 */ 51 52 /** @file bits/stl_tempbuf.h 53 * This is an internal header file, included by other library headers. 54 * Do not attempt to use it directly. @headername{memory} 55 */ 56 57 #ifndef _STL_TEMPBUF_H 58 #define _STL_TEMPBUF_H 1 59 60 #include <bits/stl_algobase.h> 61 #include <bits/stl_construct.h> 62 63 namespace std _GLIBCXX_VISIBILITY(default) 64 { 65 _GLIBCXX_BEGIN_NAMESPACE_VERSION 66 67 /** 68 * @brief Allocates a temporary buffer. 69 * @param len The number of objects of type Tp. 70 * @return See full description. 71 * 72 * Reinventing the wheel, but this time with prettier spokes! 73 * 74 * This function tries to obtain storage for @c len adjacent Tp 75 * objects. The objects themselves are not constructed, of course. 76 * A pair<> is returned containing <em>the buffer s address and 77 * capacity (in the units of sizeof(Tp)), or a pair of 0 values if 78 * no storage can be obtained.</em> Note that the capacity obtained 79 * may be less than that requested if the memory is unavailable; 80 * you should compare len with the .second return value. 81 * 82 * Provides the nothrow exception guarantee. 83 */ 84 template<typename _Tp> 85 pair<_Tp*, ptrdiff_t> 86 get_temporary_buffer(ptrdiff_t __len) 87 { 88 const ptrdiff_t __max = 89 __gnu_cxx::__numeric_traits<ptrdiff_t>::__max / sizeof(_Tp); 90 if (__len > __max) 91 __len = __max; 92 93 while (__len > 0) 94 { 95 _Tp* __tmp = static_cast<_Tp*>(::operator new(__len * sizeof(_Tp), 96 std::nothrow)); 97 if (__tmp != 0) 98 return std::pair<_Tp*, ptrdiff_t>(__tmp, __len); 99 __len /= 2; 100 } 101 return std::pair<_Tp*, ptrdiff_t>(static_cast<_Tp*>(0), 0); 102 } 103 104 /** 105 * @brief The companion to get_temporary_buffer(). 106 * @param p A buffer previously allocated by get_temporary_buffer. 107 * @return None. 108 * 109 * Frees the memory pointed to by p. 110 */ 111 template<typename _Tp> 112 inline void 113 return_temporary_buffer(_Tp* __p) 114 { ::operator delete(__p, std::nothrow); } 115 116 117 /** 118 * This class is used in two places: stl_algo.h and ext/memory, 119 * where it is wrapped as the temporary_buffer class. See 120 * temporary_buffer docs for more notes. 121 */ 122 template<typename _ForwardIterator, typename _Tp> 123 class _Temporary_buffer 124 { 125 // concept requirements 126 __glibcxx_class_requires(_ForwardIterator, _ForwardIteratorConcept) 127 128 public: 129 typedef _Tp value_type; 130 typedef value_type* pointer; 131 typedef pointer iterator; 132 typedef ptrdiff_t size_type; 133 134 protected: 135 size_type _M_original_len; 136 size_type _M_len; 137 pointer _M_buffer; 138 139 public: 140 /// As per Table mumble. 141 size_type 142 size() const 143 { return _M_len; } 144 145 /// Returns the size requested by the constructor; may be >size(). 146 size_type 147 requested_size() const 148 { return _M_original_len; } 149 150 /// As per Table mumble. 151 iterator 152 begin() 153 { return _M_buffer; } 154 155 /// As per Table mumble. 156 iterator 157 end() 158 { return _M_buffer + _M_len; } 159 160 /** 161 * Constructs a temporary buffer of a size somewhere between 162 * zero and the size of the given range. 163 */ 164 _Temporary_buffer(_ForwardIterator __first, _ForwardIterator __last); 165 166 ~_Temporary_buffer() 167 { 168 std::_Destroy(_M_buffer, _M_buffer + _M_len); 169 std::return_temporary_buffer(_M_buffer); 170 } 171 172 private: 173 // Disable copy constructor and assignment operator. 174 _Temporary_buffer(const _Temporary_buffer&); 175 176 void 177 operator=(const _Temporary_buffer&); 178 }; 179 180 181 template<bool> 182 struct __uninitialized_construct_buf_dispatch 183 { 184 template<typename _ForwardIterator, typename _Tp> 185 static void 186 __ucr(_ForwardIterator __first, _ForwardIterator __last, 187 _Tp& __value) 188 { 189 if(__first == __last) 190 return; 191 192 _ForwardIterator __cur = __first; 193 __try 194 { 195 std::_Construct(std::__addressof(*__first), 196 _GLIBCXX_MOVE(__value)); 197 _ForwardIterator __prev = __cur; 198 ++__cur; 199 for(; __cur != __last; ++__cur, ++__prev) 200 std::_Construct(std::__addressof(*__cur), 201 _GLIBCXX_MOVE(*__prev)); 202 __value = _GLIBCXX_MOVE(*__prev); 203 } 204 __catch(...) 205 { 206 std::_Destroy(__first, __cur); 207 __throw_exception_again; 208 } 209 } 210 }; 211 212 template<> 213 struct __uninitialized_construct_buf_dispatch<true> 214 { 215 template<typename _ForwardIterator, typename _Tp> 216 static void 217 __ucr(_ForwardIterator, _ForwardIterator, _Tp&) { } 218 }; 219 220 // Constructs objects in the range [first, last). 221 // Note that while these new objects will take valid values, 222 // their exact value is not defined. In particular they may 223 // be 'moved from'. 224 // 225 // While __value may altered during this algorithm, it will have 226 // the same value when the algorithm finishes, unless one of the 227 // constructions throws. 228 // 229 // Requirements: _ForwardIterator::value_type(_Tp&&) is valid. 230 template<typename _ForwardIterator, typename _Tp> 231 inline void 232 __uninitialized_construct_buf(_ForwardIterator __first, 233 _ForwardIterator __last, 234 _Tp& __value) 235 { 236 typedef typename std::iterator_traits<_ForwardIterator>::value_type 237 _ValueType; 238 239 std::__uninitialized_construct_buf_dispatch< 240 __has_trivial_constructor(_ValueType)>:: 241 __ucr(__first, __last, __value); 242 } 243 244 template<typename _ForwardIterator, typename _Tp> 245 _Temporary_buffer<_ForwardIterator, _Tp>:: 246 _Temporary_buffer(_ForwardIterator __first, _ForwardIterator __last) 247 : _M_original_len(std::distance(__first, __last)), 248 _M_len(0), _M_buffer(0) 249 { 250 __try 251 { 252 std::pair<pointer, size_type> __p(std::get_temporary_buffer< 253 value_type>(_M_original_len)); 254 _M_buffer = __p.first; 255 _M_len = __p.second; 256 if(_M_buffer) 257 std::__uninitialized_construct_buf(_M_buffer, _M_buffer + _M_len, 258 *__first); 259 } 260 __catch(...) 261 { 262 std::return_temporary_buffer(_M_buffer); 263 _M_buffer = 0; 264 _M_len = 0; 265 __throw_exception_again; 266 } 267 } 268 269 _GLIBCXX_END_NAMESPACE_VERSION 270 } // namespace 271 272 #endif /* _STL_TEMPBUF_H */ 273 274
