libstdc++-v3/include/bits/stl_tempbuf.h

   1 // Temporary buffer implementation -*- C++ -*-
   2
   3 // Copyright (C) 2001 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 2, 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 // You should have received a copy of the GNU General Public License along
  17 // with this library; see the file COPYING.  If not, write to the Free
  18 // Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
  19 // USA.
  20
  21 // As a special exception, you may use this file as part of a free software
  22 // library without restriction.  Specifically, if other files instantiate
  23 // templates or use macros or inline functions from this file, or you compile
  24 // this file and link it with other files to produce an executable, this
  25 // file does not by itself cause the resulting executable to be covered by
  26 // the GNU General Public License.  This exception does not however
  27 // invalidate any other reasons why the executable file might be covered by
  28 // the GNU General Public License.
  29
  30 /*
  31  *
  32  * Copyright (c) 1994
  33  * Hewlett-Packard Company
  34  *
  35  * Permission to use, copy, modify, distribute and sell this software
  36  * and its documentation for any purpose is hereby granted without fee,
  37  * provided that the above copyright notice appear in all copies and
  38  * that both that copyright notice and this permission notice appear
  39  * in supporting documentation.  Hewlett-Packard Company makes no
  40  * representations about the suitability of this software for any
  41  * purpose.  It is provided "as is" without express or implied warranty.
  42  *
  43  *
  44  * Copyright (c) 1996,1997
  45  * Silicon Graphics Computer Systems, Inc.
  46  *
  47  * Permission to use, copy, modify, distribute and sell this software
  48  * and its documentation for any purpose is hereby granted without fee,
  49  * provided that the above copyright notice appear in all copies and
  50  * that both that copyright notice and this permission notice appear
  51  * in supporting documentation.  Silicon Graphics makes no
  52  * representations about the suitability of this software for any
  53  * purpose.  It is provided "as is" without express or implied warranty.
  54  */
  55
  56 /** @file stl_tempbuf.h
  57  *  This is an internal header file, included by other library headers.
  58  *  You should not attempt to use it directly.
  59  */
  60
  61 #ifndef __GLIBCPP_INTERNAL_TEMPBUF_H
  62 #define __GLIBCPP_INTERNAL_TEMPBUF_H
  63
  64 namespace std
  65 {
  66
  67 template <class _Tp>
  68 pair<_Tp*, ptrdiff_t>
  69 __get_temporary_buffer(ptrdiff_t __len, _Tp*)
  70 {
  71   if (__len > ptrdiff_t(INT_MAX / sizeof(_Tp)))
  72     __len = INT_MAX / sizeof(_Tp);
  73
  74   while (__len > 0) {
  75     _Tp* __tmp = (_Tp*) malloc((size_t)__len * sizeof(_Tp));
  76     if (__tmp != 0)
  77       return pair<_Tp*, ptrdiff_t>(__tmp, __len);
  78     __len /= 2;
  79   }
  80
  81   return pair<_Tp*, ptrdiff_t>((_Tp*)0, 0);
  82 }
  83
  84 /**
  85  *  This is a mostly-useless wrapper around malloc().
  86 */
  87 template <class _Tp>
  88 inline pair<_Tp*, ptrdiff_t> get_temporary_buffer(ptrdiff_t __len) {
  89   return __get_temporary_buffer(__len, (_Tp*) 0);
  90 }
  91
  92 /**
  93  *  The companion to get_temporary_buffer().
  94 */
  95 template <class _Tp>
  96 void return_temporary_buffer(_Tp* __p) {
  97   free(__p);
  98 }
  99
 100
 101 template <class _ForwardIterator, class _Tp>
 102 class _Temporary_buffer {
 103 private:
 104   ptrdiff_t  _M_original_len;
 105   ptrdiff_t  _M_len;
 106   _Tp*       _M_buffer;
 107
 108   void _M_allocate_buffer() {
 109     _M_original_len = _M_len;
 110     _M_buffer = 0;
 111
 112     if (_M_len > (ptrdiff_t)(INT_MAX / sizeof(_Tp)))
 113       _M_len = INT_MAX / sizeof(_Tp);
 114
 115     while (_M_len > 0) {
 116       _M_buffer = (_Tp*) malloc(_M_len * sizeof(_Tp));
 117       if (_M_buffer)
 118         break;
 119       _M_len /= 2;
 120     }
 121   }
 122
 123   void _M_initialize_buffer(const _Tp&, __true_type) {}
 124   void _M_initialize_buffer(const _Tp& val, __false_type) {
 125     uninitialized_fill_n(_M_buffer, _M_len, val);
 126   }
 127
 128 public:
 129   ptrdiff_t size() const { return _M_len; }
 130   ptrdiff_t requested_size() const { return _M_original_len; }
 131   _Tp* begin() { return _M_buffer; }
 132   _Tp* end() { return _M_buffer + _M_len; }
 133
 134   _Temporary_buffer(_ForwardIterator __first, _ForwardIterator __last) {
 135     // Workaround for a __type_traits bug in the pre-7.3 compiler.
 136     typedef typename __type_traits<_Tp>::has_trivial_default_constructor
 137             _Trivial;
 138
 139     try {
 140       _M_len = distance(__first, __last);
 141       _M_allocate_buffer();
 142       if (_M_len > 0)
 143         _M_initialize_buffer(*__first, _Trivial());
 144     }
 145     catch(...)
 146       {
 147         free(_M_buffer);
 148         _M_buffer = 0;
 149         _M_len = 0;
 150         __throw_exception_again;
 151       }
 152   }
 153
 154   ~_Temporary_buffer() {
 155     _Destroy(_M_buffer, _M_buffer + _M_len);
 156     free(_M_buffer);
 157   }
 158
 159 private:
 160   // Disable copy constructor and assignment operator.
 161   _Temporary_buffer(const _Temporary_buffer&) {}
 162   void operator=(const _Temporary_buffer&) {}
 163 };
 164
 165 // Class temporary_buffer is not part of the standard.  It is an extension.
 166
 167 template <class _ForwardIterator,
 168           class _Tp
 169                     = typename iterator_traits<_ForwardIterator>::value_type
 170          >
 171 struct temporary_buffer : public _Temporary_buffer<_ForwardIterator, _Tp>
 172 {
 173   temporary_buffer(_ForwardIterator __first, _ForwardIterator __last)
 174     : _Temporary_buffer<_ForwardIterator, _Tp>(__first, __last) {}
 175   ~temporary_buffer() {}
 176 };
 177
 178 } // namespace std
 179
 180 #endif /* __GLIBCPP_INTERNAL_TEMPBUF_H */
 181
 182 // Local Variables:
 183 // mode:C++
 184 // End: