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 <__fwd/tuple.h>
  14 #include <__tuple/tuple_types.h>
  15 #include <__type_traits/is_const.h>
  16 #include <__type_traits/is_volatile.h>
  17 #include <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> struct _LIBCPP_TEMPLATE_VIS tuple_size;
  26
  27 #if !defined(_LIBCPP_CXX03_LANG)
  28 template <class _Tp, class...>
  29 using __enable_if_tuple_size_imp = _Tp;
  30
  31 template <class _Tp>
  32 struct _LIBCPP_TEMPLATE_VIS tuple_size<__enable_if_tuple_size_imp<
  33     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<
  40     volatile _Tp,
  41     __enable_if_t<!is_const<_Tp>::value>,
  42     integral_constant<size_t, sizeof(tuple_size<_Tp>)>>>
  43     : public integral_constant<size_t, tuple_size<_Tp>::value> {};
  44
  45 template <class _Tp>
  46 struct _LIBCPP_TEMPLATE_VIS tuple_size<__enable_if_tuple_size_imp<
  47     const volatile _Tp,
  48     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> struct _LIBCPP_TEMPLATE_VIS tuple_size<const _Tp> : public tuple_size<_Tp> {};
  53 template <class _Tp> struct _LIBCPP_TEMPLATE_VIS tuple_size<volatile _Tp> : public tuple_size<_Tp> {};
  54 template <class _Tp> struct _LIBCPP_TEMPLATE_VIS tuple_size<const volatile _Tp> : public tuple_size<_Tp> {};
  55 #endif
  56
  57 #ifndef _LIBCPP_CXX03_LANG
  58
  59 template <class ..._Tp>
  60 struct _LIBCPP_TEMPLATE_VIS tuple_size<tuple<_Tp...> >
  61     : public integral_constant<size_t, sizeof...(_Tp)>
  62 {
  63 };
  64
  65 template <class ..._Tp>
  66 struct _LIBCPP_TEMPLATE_VIS tuple_size<__tuple_types<_Tp...> >
  67     : public integral_constant<size_t, sizeof...(_Tp)>
  68 {
  69 };
  70
  71 #endif // _LIBCPP_CXX03_LANG
  72
  73 _LIBCPP_END_NAMESPACE_STD
  74
  75 #endif // _LIBCPP___TUPLE_TUPLE_SIZE_H