libcxx/include/__cxx03/__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 <__cxx03/__config>
  13 #include <__cxx03/__fwd/tuple.h>
  14 #include <__cxx03/__tuple/tuple_types.h>
  15 #include <__cxx03/__type_traits/is_const.h>
  16 #include <__cxx03/__type_traits/is_volatile.h>
  17 #include <__cxx03/cstddef>
  18
  19 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  20 #  pragma GCC system_header
  21 #endif
  22
  23 _LIBCPP_BEGIN_NAMESPACE_STD
  24
  25 template <class _Tp>
  26 struct _LIBCPP_TEMPLATE_VIS tuple_size;
  27
  28 #if !defined(_LIBCPP_CXX03_LANG)
  29 template <class _Tp, class...>
  30 using __enable_if_tuple_size_imp = _Tp;
  31
  32 template <class _Tp>
  33 struct _LIBCPP_TEMPLATE_VIS tuple_size<__enable_if_tuple_size_imp< const _Tp,
  34                                                                    __enable_if_t<!is_volatile<_Tp>::value>,
  35                                                                    integral_constant<size_t, sizeof(tuple_size<_Tp>)>>>
  36     : public integral_constant<size_t, tuple_size<_Tp>::value> {};
  37
  38 template <class _Tp>
  39 struct _LIBCPP_TEMPLATE_VIS tuple_size<__enable_if_tuple_size_imp< volatile _Tp,
  40                                                                    __enable_if_t<!is_const<_Tp>::value>,
  41                                                                    integral_constant<size_t, sizeof(tuple_size<_Tp>)>>>
  42     : public integral_constant<size_t, tuple_size<_Tp>::value> {};
  43
  44 template <class _Tp>
  45 struct _LIBCPP_TEMPLATE_VIS
  46 tuple_size<__enable_if_tuple_size_imp<const volatile _Tp, integral_constant<size_t, sizeof(tuple_size<_Tp>)>>>
  47     : public integral_constant<size_t, tuple_size<_Tp>::value> {};
  48
  49 #else
  50 template <class _Tp>
  51 struct _LIBCPP_TEMPLATE_VIS tuple_size<const _Tp> : public tuple_size<_Tp> {};
  52 template <class _Tp>
  53 struct _LIBCPP_TEMPLATE_VIS tuple_size<volatile _Tp> : public tuple_size<_Tp> {};
  54 template <class _Tp>
  55 struct _LIBCPP_TEMPLATE_VIS tuple_size<const volatile _Tp> : public tuple_size<_Tp> {};
  56 #endif
  57
  58 #ifndef _LIBCPP_CXX03_LANG
  59
  60 template <class... _Tp>
  61 struct _LIBCPP_TEMPLATE_VIS tuple_size<tuple<_Tp...> > : public integral_constant<size_t, sizeof...(_Tp)> {};
  62
  63 template <class... _Tp>
  64 struct _LIBCPP_TEMPLATE_VIS tuple_size<__tuple_types<_Tp...> > : public integral_constant<size_t, sizeof...(_Tp)> {};
  65
  66 #  if _LIBCPP_STD_VER >= 17
  67 template <class _Tp>
  68 inline constexpr size_t tuple_size_v = tuple_size<_Tp>::value;
  69 #  endif
  70
  71 #endif // _LIBCPP_CXX03_LANG
  72
  73 _LIBCPP_END_NAMESPACE_STD
  74
  75 #endif // _LIBCPP___TUPLE_TUPLE_SIZE_H