libstdc++
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00001 // Temporary buffer implementation -*- C++ -*- 00002 00003 // Copyright (C) 2001-2013 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 /* 00026 * 00027 * Copyright (c) 1994 00028 * Hewlett-Packard Company 00029 * 00030 * Permission to use, copy, modify, distribute and sell this software 00031 * and its documentation for any purpose is hereby granted without fee, 00032 * provided that the above copyright notice appear in all copies and 00033 * that both that copyright notice and this permission notice appear 00034 * in supporting documentation. Hewlett-Packard Company makes no 00035 * representations about the suitability of this software for any 00036 * purpose. It is provided "as is" without express or implied warranty. 00037 * 00038 * 00039 * Copyright (c) 1996,1997 00040 * Silicon Graphics Computer Systems, Inc. 00041 * 00042 * Permission to use, copy, modify, distribute and sell this software 00043 * and its documentation for any purpose is hereby granted without fee, 00044 * provided that the above copyright notice appear in all copies and 00045 * that both that copyright notice and this permission notice appear 00046 * in supporting documentation. Silicon Graphics makes no 00047 * representations about the suitability of this software for any 00048 * purpose. It is provided "as is" without express or implied warranty. 00049 */ 00050 00051 /** @file bits/stl_tempbuf.h 00052 * This is an internal header file, included by other library headers. 00053 * Do not attempt to use it directly. @headername{memory} 00054 */ 00055 00056 #ifndef _STL_TEMPBUF_H 00057 #define _STL_TEMPBUF_H 1 00058 00059 #include <bits/stl_algobase.h> 00060 #include <bits/stl_construct.h> 00061 00062 namespace std _GLIBCXX_VISIBILITY(default) 00063 { 00064 _GLIBCXX_BEGIN_NAMESPACE_VERSION 00065 00066 /** 00067 * @brief Allocates a temporary buffer. 00068 * @param __len The number of objects of type Tp. 00069 * @return See full description. 00070 * 00071 * Reinventing the wheel, but this time with prettier spokes! 00072 * 00073 * This function tries to obtain storage for @c __len adjacent Tp 00074 * objects. The objects themselves are not constructed, of course. 00075 * A pair<> is returned containing <em>the buffer s address and 00076 * capacity (in the units of sizeof(_Tp)), or a pair of 0 values if 00077 * no storage can be obtained.</em> Note that the capacity obtained 00078 * may be less than that requested if the memory is unavailable; 00079 * you should compare len with the .second return value. 00080 * 00081 * Provides the nothrow exception guarantee. 00082 */ 00083 template<typename _Tp> 00084 pair<_Tp*, ptrdiff_t> 00085 get_temporary_buffer(ptrdiff_t __len) _GLIBCXX_NOEXCEPT 00086 { 00087 const ptrdiff_t __max = 00088 __gnu_cxx::__numeric_traits<ptrdiff_t>::__max / sizeof(_Tp); 00089 if (__len > __max) 00090 __len = __max; 00091 00092 while (__len > 0) 00093 { 00094 _Tp* __tmp = static_cast<_Tp*>(::operator new(__len * sizeof(_Tp), 00095 std::nothrow)); 00096 if (__tmp != 0) 00097 return std::pair<_Tp*, ptrdiff_t>(__tmp, __len); 00098 __len /= 2; 00099 } 00100 return std::pair<_Tp*, ptrdiff_t>(static_cast<_Tp*>(0), 0); 00101 } 00102 00103 /** 00104 * @brief The companion to get_temporary_buffer(). 00105 * @param __p A buffer previously allocated by get_temporary_buffer. 00106 * @return None. 00107 * 00108 * Frees the memory pointed to by __p. 00109 */ 00110 template<typename _Tp> 00111 inline void 00112 return_temporary_buffer(_Tp* __p) 00113 { ::operator delete(__p, std::nothrow); } 00114 00115 00116 /** 00117 * This class is used in two places: stl_algo.h and ext/memory, 00118 * where it is wrapped as the temporary_buffer class. See 00119 * temporary_buffer docs for more notes. 00120 */ 00121 template<typename _ForwardIterator, typename _Tp> 00122 class _Temporary_buffer 00123 { 00124 // concept requirements 00125 __glibcxx_class_requires(_ForwardIterator, _ForwardIteratorConcept) 00126 00127 public: 00128 typedef _Tp value_type; 00129 typedef value_type* pointer; 00130 typedef pointer iterator; 00131 typedef ptrdiff_t size_type; 00132 00133 protected: 00134 size_type _M_original_len; 00135 size_type _M_len; 00136 pointer _M_buffer; 00137 00138 public: 00139 /// As per Table mumble. 00140 size_type 00141 size() const 00142 { return _M_len; } 00143 00144 /// Returns the size requested by the constructor; may be >size(). 00145 size_type 00146 requested_size() const 00147 { return _M_original_len; } 00148 00149 /// As per Table mumble. 00150 iterator 00151 begin() 00152 { return _M_buffer; } 00153 00154 /// As per Table mumble. 00155 iterator 00156 end() 00157 { return _M_buffer + _M_len; } 00158 00159 /** 00160 * Constructs a temporary buffer of a size somewhere between 00161 * zero and the size of the given range. 00162 */ 00163 _Temporary_buffer(_ForwardIterator __first, _ForwardIterator __last); 00164 00165 ~_Temporary_buffer() 00166 { 00167 std::_Destroy(_M_buffer, _M_buffer + _M_len); 00168 std::return_temporary_buffer(_M_buffer); 00169 } 00170 00171 private: 00172 // Disable copy constructor and assignment operator. 00173 _Temporary_buffer(const _Temporary_buffer&); 00174 00175 void 00176 operator=(const _Temporary_buffer&); 00177 }; 00178 00179 00180 template<bool> 00181 struct __uninitialized_construct_buf_dispatch 00182 { 00183 template<typename _Pointer, typename _ForwardIterator> 00184 static void 00185 __ucr(_Pointer __first, _Pointer __last, 00186 _ForwardIterator __seed) 00187 { 00188 if(__first == __last) 00189 return; 00190 00191 _Pointer __cur = __first; 00192 __try 00193 { 00194 std::_Construct(std::__addressof(*__first), 00195 _GLIBCXX_MOVE(*__seed)); 00196 _Pointer __prev = __cur; 00197 ++__cur; 00198 for(; __cur != __last; ++__cur, ++__prev) 00199 std::_Construct(std::__addressof(*__cur), 00200 _GLIBCXX_MOVE(*__prev)); 00201 *__seed = _GLIBCXX_MOVE(*__prev); 00202 } 00203 __catch(...) 00204 { 00205 std::_Destroy(__first, __cur); 00206 __throw_exception_again; 00207 } 00208 } 00209 }; 00210 00211 template<> 00212 struct __uninitialized_construct_buf_dispatch<true> 00213 { 00214 template<typename _Pointer, typename _ForwardIterator> 00215 static void 00216 __ucr(_Pointer, _Pointer, _ForwardIterator) { } 00217 }; 00218 00219 // Constructs objects in the range [first, last). 00220 // Note that while these new objects will take valid values, 00221 // their exact value is not defined. In particular they may 00222 // be 'moved from'. 00223 // 00224 // While *__seed may be altered during this algorithm, it will have 00225 // the same value when the algorithm finishes, unless one of the 00226 // constructions throws. 00227 // 00228 // Requirements: _Pointer::value_type(_Tp&&) is valid. 00229 template<typename _Pointer, typename _ForwardIterator> 00230 inline void 00231 __uninitialized_construct_buf(_Pointer __first, _Pointer __last, 00232 _ForwardIterator __seed) 00233 { 00234 typedef typename std::iterator_traits<_Pointer>::value_type 00235 _ValueType; 00236 00237 std::__uninitialized_construct_buf_dispatch< 00238 __has_trivial_constructor(_ValueType)>:: 00239 __ucr(__first, __last, __seed); 00240 } 00241 00242 template<typename _ForwardIterator, typename _Tp> 00243 _Temporary_buffer<_ForwardIterator, _Tp>:: 00244 _Temporary_buffer(_ForwardIterator __first, _ForwardIterator __last) 00245 : _M_original_len(std::distance(__first, __last)), 00246 _M_len(0), _M_buffer(0) 00247 { 00248 __try 00249 { 00250 std::pair<pointer, size_type> __p(std::get_temporary_buffer< 00251 value_type>(_M_original_len)); 00252 _M_buffer = __p.first; 00253 _M_len = __p.second; 00254 if (_M_buffer) 00255 std::__uninitialized_construct_buf(_M_buffer, _M_buffer + _M_len, 00256 __first); 00257 } 00258 __catch(...) 00259 { 00260 std::return_temporary_buffer(_M_buffer); 00261 _M_buffer = 0; 00262 _M_len = 0; 00263 __throw_exception_again; 00264 } 00265 } 00266 00267 _GLIBCXX_END_NAMESPACE_VERSION 00268 } // namespace 00269 00270 #endif /* _STL_TEMPBUF_H */ 00271