libkern/os/cpp_util.h

   1 #ifndef _OS_CPP_UTIL_H
   2 #define _OS_CPP_UTIL_H
   3
   4 #include <sys/cdefs.h>
   5
   6 #if __has_feature(cxx_nullptr) && __has_feature(cxx_decltype)
   7 # define OS_HAS_NULLPTR 1
   8 #endif
   9
  10 #if __has_feature(cxx_rvalue_references) || __has_extension(cxx_rvalue_references)
  11 # define OS_HAS_RVALUE_REFERENCES 1
  12 #endif
  13
  14 void* operator new(size_t, void*);
  15
  16 namespace os {
  17 #if OS_HAS_NULLPTR
  18 typedef decltype(nullptr) nullptr_t;
  19 #endif
  20
  21 /*
  22  * Reference removal
  23  */
  24
  25 template <class _T> struct remove_reference       {typedef _T type;};
  26 template <class _T> struct remove_reference<_T&>  {typedef _T type;};
  27 template <class _T> struct remove_reference<_T &&> {typedef _T type;};
  28 template <class _T> using remove_reference_t = typename remove_reference<_T>::type;
  29
  30 /*
  31  * Const removal
  32  */
  33
  34 template <class _T> struct remove_const           {typedef _T type;};
  35 template <class _T> struct remove_const<const _T> {typedef _T type;};
  36 template <class _T> using remove_const_t = typename remove_const<_T>::type;
  37
  38 template <class T> struct is_lvalue_reference { static constexpr bool value = false; };
  39 template <class T> struct is_lvalue_reference<T&> { static constexpr bool value = true; };
  40
  41 /*
  42  * Move
  43  */
  44
  45 template <class _T>
  46 inline typename remove_reference<_T>::type &&
  47 move(_T && _t)
  48 {
  49         typedef typename os::remove_reference<_T>::type _U;
  50         return static_cast<_U &&>(_t);
  51 }
  52
  53 template <class T>
  54 T*
  55 move(T* first, T* last, T* d_first)
  56 {
  57         for (; first != last; ++d_first, (void)++first) {
  58                 *d_first = os::move(*first);
  59         }
  60         return d_first;
  61 }
  62
  63 template <class T>
  64 constexpr T && forward(os::remove_reference_t<T>&t) noexcept {
  65         return static_cast<T &&>(t);
  66 }
  67
  68 template <class T>
  69 constexpr T && forward(os::remove_reference_t<T>&& t) noexcept {
  70         static_assert(!os::is_lvalue_reference<T>::value,
  71             "can not forward an rvalue as an lvalue");
  72         return static_cast<T &&>(t);
  73 }
  74
  75 // Moves [first, last) into the range ending at d_last,
  76 // proceeding backwards (from last to first)
  77 // UB if d_last is within (first, last]
  78 template <class T>
  79 T*
  80 move_backward(T* first, T* last, T* d_last)
  81 {
  82         while (first != last) {
  83                 *(--d_last) = os::move(*(--last));
  84         }
  85         return d_last;
  86 }
  87
  88 template <class T>
  89 T*
  90 uninitialized_move(T* first, T* last, T* d_first)
  91 {
  92         for (; first != last; ++d_first, (void) ++first) {
  93                 ::new (static_cast<void*>(d_first)) T(os::move(*first));
  94         }
  95         return first;
  96 }
  97
  98 template <class T>
  99 void
 100 destroy(T* first, T* last)
 101 {
 102         for (; first != last; ++first) {
 103                 first->~T();
 104         }
 105 }
 106
 107 template <class T>
 108 void
 109 uninitialized_value_construct(T* first, T* last)
 110 {
 111         for (; first != last; ++first) {
 112                 ::new (static_cast<void*>(first)) T();
 113         }
 114 }
 115 }
 116
 117 #endif /* _OS_CPP_UTIL_H */