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 /* NOTE: This is an internal header file, included by other STL headers.
  57  *   You should not attempt to use it directly.
  58  */
  59
  60 #ifndef __SGI_STL_INTERNAL_TEMPBUF_H
  61 #define __SGI_STL_INTERNAL_TEMPBUF_H
  62
  63 namespace std
  64 {
  65
  66 template <class _Tp>
  67 pair<_Tp*, ptrdiff_t>
  68 __get_temporary_buffer(ptrdiff_t __len, _Tp*)
  69 {
  70   if (__len > ptrdiff_t(INT_MAX / sizeof(_Tp)))
  71     __len = INT_MAX / sizeof(_Tp);
  72
  73   while (__len > 0) {
  74     _Tp* __tmp = (_Tp*) malloc((size_t)__len * sizeof(_Tp));
  75     if (__tmp != 0)
  76       return pair<_Tp*, ptrdiff_t>(__tmp, __len);
  77     __len /= 2;
  78   }
  79
  80   return pair<_Tp*, ptrdiff_t>((_Tp*)0, 0);
  81 }
  82
  83 template <class _Tp>
  84 inline pair<_Tp*, ptrdiff_t> get_temporary_buffer(ptrdiff_t __len) {
  85   return __get_temporary_buffer(__len, (_Tp*) 0);
  86 }
  87
  88 // This overload is not required by the standard; it is an extension.
  89 // It is supported for backward compatibility with the HP STL, and
  90 // because not all compilers support the language feature (explicit
  91 // function template arguments) that is required for the standard
  92 // version of get_temporary_buffer.
  93 template <class _Tp>
  94 inline pair<_Tp*, ptrdiff_t> get_temporary_buffer(ptrdiff_t __len, _Tp*) {
  95   return __get_temporary_buffer(__len, (_Tp*) 0);
  96 }
  97
  98 template <class _Tp>
  99 void return_temporary_buffer(_Tp* __p) {
 100   free(__p);
 101 }
 102
 103 template <class _ForwardIterator, class _Tp>
 104 class _Temporary_buffer {
 105 private:
 106   ptrdiff_t  _M_original_len;
 107   ptrdiff_t  _M_len;
 108   _Tp*       _M_buffer;
 109
 110   void _M_allocate_buffer() {
 111     _M_original_len = _M_len;
 112     _M_buffer = 0;
 113
 114     if (_M_len > (ptrdiff_t)(INT_MAX / sizeof(_Tp)))
 115       _M_len = INT_MAX / sizeof(_Tp);
 116
 117     while (_M_len > 0) {
 118       _M_buffer = (_Tp*) malloc(_M_len * sizeof(_Tp));
 119       if (_M_buffer)
 120         break;
 121       _M_len /= 2;
 122     }
 123   }
 124
 125   void _M_initialize_buffer(const _Tp&, __true_type) {}
 126   void _M_initialize_buffer(const _Tp& val, __false_type) {
 127     uninitialized_fill_n(_M_buffer, _M_len, val);
 128   }
 129
 130 public:
 131   ptrdiff_t size() const { return _M_len; }
 132   ptrdiff_t requested_size() const { return _M_original_len; }
 133   _Tp* begin() { return _M_buffer; }
 134   _Tp* end() { return _M_buffer + _M_len; }
 135
 136   _Temporary_buffer(_ForwardIterator __first, _ForwardIterator __last) {
 137     // Workaround for a __type_traits bug in the pre-7.3 compiler.
 138     typedef typename __type_traits<_Tp>::has_trivial_default_constructor
 139             _Trivial;
 140
 141     try {
 142       _M_len = 0;
 143       distance(__first, __last, _M_len);
 144       _M_allocate_buffer();
 145       if (_M_len > 0)
 146         _M_initialize_buffer(*__first, _Trivial());
 147     }
 148     catch(...)
 149       {
 150         free(_M_buffer);
 151         _M_buffer = 0;
 152         _M_len = 0;
 153         __throw_exception_again;
 154       }
 155   }
 156
 157   ~_Temporary_buffer() {
 158     _Destroy(_M_buffer, _M_buffer + _M_len);
 159     free(_M_buffer);
 160   }
 161
 162 private:
 163   // Disable copy constructor and assignment operator.
 164   _Temporary_buffer(const _Temporary_buffer&) {}
 165   void operator=(const _Temporary_buffer&) {}
 166 };
 167
 168 // Class temporary_buffer is not part of the standard.  It is an extension.
 169
 170 template <class _ForwardIterator,
 171           class _Tp
 172                     = typename iterator_traits<_ForwardIterator>::value_type
 173          >
 174 struct temporary_buffer : public _Temporary_buffer<_ForwardIterator, _Tp>
 175 {
 176   temporary_buffer(_ForwardIterator __first, _ForwardIterator __last)
 177     : _Temporary_buffer<_ForwardIterator, _Tp>(__first, __last) {}
 178   ~temporary_buffer() {}
 179 };
 180
 181 } // namespace std
 182
 183 #endif /* __SGI_STL_INTERNAL_TEMPBUF_H */
 184
 185 // Local Variables:
 186 // mode:C++
 187 // End: