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

   1 /*
   2  *
   3  * Copyright (c) 1994
   4  * Hewlett-Packard Company
   5  *
   6  * Permission to use, copy, modify, distribute and sell this software
   7  * and its documentation for any purpose is hereby granted without fee,
   8  * provided that the above copyright notice appear in all copies and
   9  * that both that copyright notice and this permission notice appear
  10  * in supporting documentation.  Hewlett-Packard Company makes no
  11  * representations about the suitability of this software for any
  12  * purpose.  It is provided "as is" without express or implied warranty.
  13  *
  14  *
  15  * Copyright (c) 1996,1997
  16  * Silicon Graphics Computer Systems, Inc.
  17  *
  18  * Permission to use, copy, modify, distribute and sell this software
  19  * and its documentation for any purpose is hereby granted without fee,
  20  * provided that the above copyright notice appear in all copies and
  21  * that both that copyright notice and this permission notice appear
  22  * in supporting documentation.  Silicon Graphics makes no
  23  * representations about the suitability of this software for any
  24  * purpose.  It is provided "as is" without express or implied warranty.
  25  */
  26
  27 /* NOTE: This is an internal header file, included by other STL headers.
  28  *   You should not attempt to use it directly.
  29  */
  30
  31 #ifndef __SGI_STL_INTERNAL_TEMPBUF_H
  32 #define __SGI_STL_INTERNAL_TEMPBUF_H
  33
  34 namespace std
  35 {
  36
  37 template <class _Tp>
  38 pair<_Tp*, ptrdiff_t>
  39 __get_temporary_buffer(ptrdiff_t __len, _Tp*)
  40 {
  41   if (__len > ptrdiff_t(INT_MAX / sizeof(_Tp)))
  42     __len = INT_MAX / sizeof(_Tp);
  43
  44   while (__len > 0) {
  45     _Tp* __tmp = (_Tp*) malloc((size_t)__len * sizeof(_Tp));
  46     if (__tmp != 0)
  47       return pair<_Tp*, ptrdiff_t>(__tmp, __len);
  48     __len /= 2;
  49   }
  50
  51   return pair<_Tp*, ptrdiff_t>((_Tp*)0, 0);
  52 }
  53
  54 template <class _Tp>
  55 inline pair<_Tp*, ptrdiff_t> get_temporary_buffer(ptrdiff_t __len) {
  56   return __get_temporary_buffer(__len, (_Tp*) 0);
  57 }
  58
  59 // This overload is not required by the standard; it is an extension.
  60 // It is supported for backward compatibility with the HP STL, and
  61 // because not all compilers support the language feature (explicit
  62 // function template arguments) that is required for the standard
  63 // version of get_temporary_buffer.
  64 template <class _Tp>
  65 inline pair<_Tp*, ptrdiff_t> get_temporary_buffer(ptrdiff_t __len, _Tp*) {
  66   return __get_temporary_buffer(__len, (_Tp*) 0);
  67 }
  68
  69 template <class _Tp>
  70 void return_temporary_buffer(_Tp* __p) {
  71   free(__p);
  72 }
  73
  74 template <class _ForwardIterator, class _Tp>
  75 class _Temporary_buffer {
  76 private:
  77   ptrdiff_t  _M_original_len;
  78   ptrdiff_t  _M_len;
  79   _Tp*       _M_buffer;
  80
  81   void _M_allocate_buffer() {
  82     _M_original_len = _M_len;
  83     _M_buffer = 0;
  84
  85     if (_M_len > (ptrdiff_t)(INT_MAX / sizeof(_Tp)))
  86       _M_len = INT_MAX / sizeof(_Tp);
  87
  88     while (_M_len > 0) {
  89       _M_buffer = (_Tp*) malloc(_M_len * sizeof(_Tp));
  90       if (_M_buffer)
  91         break;
  92       _M_len /= 2;
  93     }
  94   }
  95
  96   void _M_initialize_buffer(const _Tp&, __true_type) {}
  97   void _M_initialize_buffer(const _Tp& val, __false_type) {
  98     uninitialized_fill_n(_M_buffer, _M_len, val);
  99   }
 100
 101 public:
 102   ptrdiff_t size() const { return _M_len; }
 103   ptrdiff_t requested_size() const { return _M_original_len; }
 104   _Tp* begin() { return _M_buffer; }
 105   _Tp* end() { return _M_buffer + _M_len; }
 106
 107   _Temporary_buffer(_ForwardIterator __first, _ForwardIterator __last) {
 108     // Workaround for a __type_traits bug in the pre-7.3 compiler.
 109     typedef typename __type_traits<_Tp>::has_trivial_default_constructor
 110             _Trivial;
 111
 112     __STL_TRY {
 113       _M_len = 0;
 114       distance(__first, __last, _M_len);
 115       _M_allocate_buffer();
 116       if (_M_len > 0)
 117         _M_initialize_buffer(*__first, _Trivial());
 118     }
 119     __STL_UNWIND(free(_M_buffer); _M_buffer = 0; _M_len = 0);
 120   }
 121
 122   ~_Temporary_buffer() {
 123     destroy(_M_buffer, _M_buffer + _M_len);
 124     free(_M_buffer);
 125   }
 126
 127 private:
 128   // Disable copy constructor and assignment operator.
 129   _Temporary_buffer(const _Temporary_buffer&) {}
 130   void operator=(const _Temporary_buffer&) {}
 131 };
 132
 133 // Class temporary_buffer is not part of the standard.  It is an extension.
 134
 135 template <class _ForwardIterator,
 136           class _Tp
 137                     = typename iterator_traits<_ForwardIterator>::value_type
 138          >
 139 struct temporary_buffer : public _Temporary_buffer<_ForwardIterator, _Tp>
 140 {
 141   temporary_buffer(_ForwardIterator __first, _ForwardIterator __last)
 142     : _Temporary_buffer<_ForwardIterator, _Tp>(__first, __last) {}
 143   ~temporary_buffer() {}
 144 };
 145
 146 } // namespace std
 147
 148 #endif /* __SGI_STL_INTERNAL_TEMPBUF_H */
 149
 150 // Local Variables:
 151 // mode:C++
 152 // End: