libcxx/include/__tuple/tuple_size.h

   1 //===----------------------------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #ifndef _LIBCPP___TUPLE_TUPLE_SIZE_H
  10 #define _LIBCPP___TUPLE_TUPLE_SIZE_H
  11
  12 #include <__config>
  13 #include <__cstddef/size_t.h>
  14 #include <__fwd/tuple.h>
  15 #include <__tuple/tuple_types.h>
  16 #include <__type_traits/enable_if.h>
  17 #include <__type_traits/integral_constant.h>
  18 #include <__type_traits/is_const.h>
  19 #include <__type_traits/is_volatile.h>
  20
  21 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  22 #  pragma GCC system_header
  23 #endif
  24
  25 _LIBCPP_BEGIN_NAMESPACE_STD
  26
  27 template <class _Tp>
  28 struct _LIBCPP_TEMPLATE_VIS tuple_size;
  29
  30 #if !defined(_LIBCPP_CXX03_LANG)
  31 template <class _Tp, class...>
  32 using __enable_if_tuple_size_imp = _Tp;
  33
  34 template <class _Tp>
  35 struct _LIBCPP_TEMPLATE_VIS tuple_size<__enable_if_tuple_size_imp< const _Tp,
  36                                                                    __enable_if_t<!is_volatile<_Tp>::value>,
  37                                                                    integral_constant<size_t, sizeof(tuple_size<_Tp>)>>>
  38     : public integral_constant<size_t, tuple_size<_Tp>::value> {};
  39
  40 template <class _Tp>
  41 struct _LIBCPP_TEMPLATE_VIS tuple_size<__enable_if_tuple_size_imp< volatile _Tp,
  42                                                                    __enable_if_t<!is_const<_Tp>::value>,
  43                                                                    integral_constant<size_t, sizeof(tuple_size<_Tp>)>>>
  44     : public integral_constant<size_t, tuple_size<_Tp>::value> {};
  45
  46 template <class _Tp>
  47 struct _LIBCPP_TEMPLATE_VIS
  48 tuple_size<__enable_if_tuple_size_imp<const volatile _Tp, integral_constant<size_t, sizeof(tuple_size<_Tp>)>>>
  49     : public integral_constant<size_t, tuple_size<_Tp>::value> {};
  50
  51 #else
  52 template <class _Tp>
  53 struct _LIBCPP_TEMPLATE_VIS tuple_size<const _Tp> : public tuple_size<_Tp> {};
  54 template <class _Tp>
  55 struct _LIBCPP_TEMPLATE_VIS tuple_size<volatile _Tp> : public tuple_size<_Tp> {};
  56 template <class _Tp>
  57 struct _LIBCPP_TEMPLATE_VIS tuple_size<const volatile _Tp> : public tuple_size<_Tp> {};
  58 #endif
  59
  60 #ifndef _LIBCPP_CXX03_LANG
  61
  62 template <class... _Tp>
  63 struct _LIBCPP_TEMPLATE_VIS tuple_size<tuple<_Tp...> > : public integral_constant<size_t, sizeof...(_Tp)> {};
  64
  65 template <class... _Tp>
  66 struct _LIBCPP_TEMPLATE_VIS tuple_size<__tuple_types<_Tp...> > : public integral_constant<size_t, sizeof...(_Tp)> {};
  67
  68 #  if _LIBCPP_STD_VER >= 17
  69 template <class _Tp>
  70 inline constexpr size_t tuple_size_v = tuple_size<_Tp>::value;
  71 #  endif
  72
  73 #endif // _LIBCPP_CXX03_LANG
  74
  75 _LIBCPP_END_NAMESPACE_STD
  76
  77 #endif // _LIBCPP___TUPLE_TUPLE_SIZE_H