00001 // Temporary buffer implementation -*- C++ -*- 00002 00003 // Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010 00004 // Free Software Foundation, Inc. 00005 // 00006 // This file is part of the GNU ISO C++ Library. This library is free 00007 // software; you can redistribute it and/or modify it under the 00008 // terms of the GNU General Public License as published by the 00009 // Free Software Foundation; either version 3, or (at your option) 00010 // any later version. 00011 00012 // This library is distributed in the hope that it will be useful, 00013 // but WITHOUT ANY WARRANTY; without even the implied warranty of 00014 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 00015 // GNU General Public License for more details. 00016 00017 // Under Section 7 of GPL version 3, you are granted additional 00018 // permissions described in the GCC Runtime Library Exception, version 00019 // 3.1, as published by the Free Software Foundation. 00020 00021 // You should have received a copy of the GNU General Public License and 00022 // a copy of the GCC Runtime Library Exception along with this program; 00023 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 00024 // <http://www.gnu.org/licenses/>. 00025 00026 /* 00027 * 00028 * Copyright (c) 1994 00029 * Hewlett-Packard Company 00030 * 00031 * Permission to use, copy, modify, distribute and sell this software 00032 * and its documentation for any purpose is hereby granted without fee, 00033 * provided that the above copyright notice appear in all copies and 00034 * that both that copyright notice and this permission notice appear 00035 * in supporting documentation. Hewlett-Packard Company makes no 00036 * representations about the suitability of this software for any 00037 * purpose. It is provided "as is" without express or implied warranty. 00038 * 00039 * 00040 * Copyright (c) 1996,1997 00041 * Silicon Graphics Computer Systems, Inc. 00042 * 00043 * Permission to use, copy, modify, distribute and sell this software 00044 * and its documentation for any purpose is hereby granted without fee, 00045 * provided that the above copyright notice appear in all copies and 00046 * that both that copyright notice and this permission notice appear 00047 * in supporting documentation. Silicon Graphics makes no 00048 * representations about the suitability of this software for any 00049 * purpose. It is provided "as is" without express or implied warranty. 00050 */ 00051 00052 /** @file stl_tempbuf.h 00053 * This is an internal header file, included by other library headers. 00054 * You should not attempt to use it directly. 00055 */ 00056 00057 #ifndef _STL_TEMPBUF_H 00058 #define _STL_TEMPBUF_H 1 00059 00060 #include <bits/stl_algobase.h> 00061 #include <bits/stl_construct.h> 00062 #include <bits/stl_uninitialized.h> 00063 00064 _GLIBCXX_BEGIN_NAMESPACE(std) 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) 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 template<typename _ForwardIterator, typename _Tp> 00180 _Temporary_buffer<_ForwardIterator, _Tp>:: 00181 _Temporary_buffer(_ForwardIterator __first, _ForwardIterator __last) 00182 : _M_original_len(std::distance(__first, __last)), 00183 _M_len(0), _M_buffer(0) 00184 { 00185 __try 00186 { 00187 std::pair<pointer, size_type> __p(std::get_temporary_buffer< 00188 value_type>(_M_original_len)); 00189 _M_buffer = __p.first; 00190 _M_len = __p.second; 00191 if(_M_buffer) 00192 std::__uninitialized_construct_range(_M_buffer, _M_buffer + _M_len, 00193 *__first); 00194 } 00195 __catch(...) 00196 { 00197 std::return_temporary_buffer(_M_buffer); 00198 _M_buffer = 0; 00199 _M_len = 0; 00200 __throw_exception_again; 00201 } 00202 } 00203 00204 _GLIBCXX_END_NAMESPACE 00205 00206 #endif /* _STL_TEMPBUF_H */ 00207