include/c++/stlport/stl/_move_construct_fwk.h

   1 /*
   2  *
   3  * Copyright (c) 2003
   4  * Francois Dumont
   5  *
   6  * This material is provided "as is", with absolutely no warranty expressed
   7  * or implied. Any use is at your own risk.
   8  *
   9  * Permission to use or copy this software for any purpose is hereby granted
  10  * without fee, provided the above notices are retained on all copies.
  11  * Permission to modify the code and to distribute modified code is granted,
  12  * provided the above notices are retained, and a notice that the code was
  13  * modified is included with the above copyright notice.
  14  *
  15  */
  16
  17 #ifndef _STLP_MOVE_CONSTRUCT_FWK_H
  18 #define _STLP_MOVE_CONSTRUCT_FWK_H
  19
  20 #ifndef _STLP_TYPE_TRAITS_H
  21 #  include <stl/type_traits.h>
  22 #endif
  23
  24 _STLP_BEGIN_NAMESPACE
  25
  26 /*************************************************************
  27  * Move constructor framework
  28  *************************************************************/
  29
  30 /*************************************************************
  31  *Partial move:
  32  *The source HAS to be a valid instance after the move!
  33  *************************************************************/
  34 template <class _Tp>
  35 class __move_source {
  36 public:
  37   explicit __move_source (_Tp &_src) : _M_data(_src)
  38   {}
  39
  40   _Tp& get() const
  41   { return _M_data; }
  42 private:
  43   _Tp &_M_data;
  44
  45   //We explicitely forbid assignment to avoid warning:
  46   typedef __move_source<_Tp> _Self;
  47   _Self& operator = (_Self const&);
  48 };
  49
  50 //Class used to signal move constructor support, implementation and type.
  51 template <class _Tp>
  52 struct __move_traits {
  53   /*
  54    * implemented tells if a the special move constructor has to be called or the classic
  55    * copy constructor is just fine. Most of the time the copy constructor is fine only
  56    * if the following info is true.
  57    */
  58 #if defined (_STLP_USE_PARTIAL_SPEC_WORKAROUND) && \
  59    !defined (_STLP_CLASS_PARTIAL_SPECIALIZATION) && \
  60    !defined (_STLP_NO_MOVE_SEMANTIC)
  61   typedef typename _IsSTLportClass<_Tp>::_Ret implemented;
  62 #else
  63   typedef __false_type implemented;
  64 #endif
  65   /*
  66    * complete tells if the move is complete or partial, that is to say, does the source
  67    * needs to be destroyed once it has been moved.
  68    */
  69 #  if defined (__BORLANDC__) && (__BORLANDC__ >= 0x564)
  70   typedef __type_traits<_Tp>::has_trivial_destructor _TpMoveComplete;
  71   typedef typename __bool2type<__type2bool<_TpMoveComplete>::_Ret>::_Ret complete;
  72 #  else
  73   typedef typename __type_traits<_Tp>::has_trivial_destructor complete;
  74 #  endif
  75 };
  76
  77 _STLP_MOVE_TO_PRIV_NAMESPACE
  78
  79 /*
  80  * This struct should never be used if the user has not explicitely stipulated
  81  * that its class support the full move concept. To check that the return type
  82  * in such a case will be __invalid_source<_Tp> to generate a compile error
  83  * revealing the configuration problem.
  84  */
  85 template <class _Tp>
  86 struct _MoveSourceTraits {
  87   typedef typename __move_traits<_Tp>::implemented _MvImpRet;
  88 #if defined (__BORLANDC__)
  89   typedef typename __selectT<_MvImpRet,
  90 #else
  91   enum {_MvImp = __type2bool<_MvImpRet>::_Ret};
  92   typedef typename __select<_MvImp,
  93 #endif
  94                             __move_source<_Tp>,
  95                             _Tp const&>::_Ret _Type;
  96 };
  97
  98 //The helper function
  99 template <class _Tp>
 100 inline _STLP_TYPENAME_ON_RETURN_TYPE _MoveSourceTraits<_Tp>::_Type
 101 _AsMoveSource (_Tp &src) {
 102   typedef typename _MoveSourceTraits<_Tp>::_Type _SrcType;
 103   return _SrcType(src);
 104 }
 105
 106 //Helper structs used for many class.
 107 template <class _Tp>
 108 struct __move_traits_aux {
 109   typedef typename __move_traits<_Tp>::implemented implemented;
 110   typedef typename __move_traits<_Tp>::complete complete;
 111 };
 112
 113 template <class _Tp1, class _Tp2>
 114 struct __move_traits_aux2 {
 115   typedef __move_traits<_Tp1> _MoveTraits1;
 116   typedef __move_traits<_Tp2> _MoveTraits2;
 117
 118   typedef typename _Lor2<typename _MoveTraits1::implemented,
 119                          typename _MoveTraits2::implemented>::_Ret implemented;
 120   typedef typename _Land2<typename _MoveTraits1::complete,
 121                           typename _MoveTraits2::complete>::_Ret complete;
 122 };
 123
 124 /*
 125  * Most of the time a class implement a move constructor but its use depends
 126  * on a third party, this is what the following struct are for.
 127  */
 128 template <class _Tp>
 129 struct __move_traits_help {
 130   typedef __true_type implemented;
 131   typedef typename __move_traits<_Tp>::complete complete;
 132 };
 133
 134 template <class _Tp1, class _Tp2>
 135 struct __move_traits_help1 {
 136   typedef __move_traits<_Tp1> _MoveTraits1;
 137   typedef __move_traits<_Tp2> _MoveTraits2;
 138
 139   typedef typename _Lor2<typename _MoveTraits1::implemented,
 140                          typename _MoveTraits2::implemented>::_Ret implemented;
 141   typedef typename _Land2<typename _MoveTraits1::complete,
 142                           typename _MoveTraits2::complete>::_Ret complete;
 143 };
 144
 145 template <class _Tp1, class _Tp2>
 146 struct __move_traits_help2 {
 147   typedef __move_traits<_Tp1> _MoveTraits1;
 148   typedef __move_traits<_Tp2> _MoveTraits2;
 149
 150   typedef __true_type implemented;
 151   typedef typename _Land2<typename _MoveTraits1::complete,
 152                           typename _MoveTraits2::complete>::_Ret complete;
 153 };
 154
 155 _STLP_MOVE_TO_STD_NAMESPACE
 156
 157 _STLP_END_NAMESPACE
 158
 159 #endif /* _STLP_MOVE_CONSTRUCT_FWK_H */