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 stl_tempbuf.h 53 * This is an internal header file, included by other library headers. 54 * You should not attempt to use it directly. 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#include <bits/stl_uninitialized.h> 63 64_GLIBCXX_BEGIN_NAMESPACE(std) 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) 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 template<typename _ForwardIterator, typename _Tp> 180 _Temporary_buffer<_ForwardIterator, _Tp>:: 181 _Temporary_buffer(_ForwardIterator __first, _ForwardIterator __last) 182 : _M_original_len(std::distance(__first, __last)), 183 _M_len(0), _M_buffer(0) 184 { 185 __try 186 { 187 std::pair<pointer, size_type> __p(std::get_temporary_buffer< 188 value_type>(_M_original_len)); 189 _M_buffer = __p.first; 190 _M_len = __p.second; 191 if(_M_buffer) 192 std::__uninitialized_construct_range(_M_buffer, _M_buffer + _M_len, 193 *__first); 194 } 195 __catch(...) 196 { 197 std::return_temporary_buffer(_M_buffer); 198 _M_buffer = 0; 199 _M_len = 0; 200 __throw_exception_again; 201 } 202 } 203 204_GLIBCXX_END_NAMESPACE 205 206#endif /* _STL_TEMPBUF_H */ 207 208