libcxx/include/__cxx03/__tuple/tuple_element.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_ELEMENT_H
  10 #define _LIBCPP___TUPLE_TUPLE_ELEMENT_H
  11
  12 #include <__cxx03/__config>
  13 #include <__cxx03/__tuple/tuple_indices.h>
  14 #include <__cxx03/__tuple/tuple_types.h>
  15 #include <__cxx03/cstddef>
  16
  17 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  18 #  pragma GCC system_header
  19 #endif
  20
  21 _LIBCPP_BEGIN_NAMESPACE_STD
  22
  23 template <size_t _Ip, class _Tp>
  24 struct _LIBCPP_TEMPLATE_VIS tuple_element;
  25
  26 template <size_t _Ip, class _Tp>
  27 struct _LIBCPP_TEMPLATE_VIS tuple_element<_Ip, const _Tp> {
  28   typedef _LIBCPP_NODEBUG const typename tuple_element<_Ip, _Tp>::type type;
  29 };
  30
  31 template <size_t _Ip, class _Tp>
  32 struct _LIBCPP_TEMPLATE_VIS tuple_element<_Ip, volatile _Tp> {
  33   typedef _LIBCPP_NODEBUG volatile typename tuple_element<_Ip, _Tp>::type type;
  34 };
  35
  36 template <size_t _Ip, class _Tp>
  37 struct _LIBCPP_TEMPLATE_VIS tuple_element<_Ip, const volatile _Tp> {
  38   typedef _LIBCPP_NODEBUG const volatile typename tuple_element<_Ip, _Tp>::type type;
  39 };
  40
  41 #ifndef _LIBCPP_CXX03_LANG
  42
  43 template <size_t _Ip, class... _Types>
  44 struct _LIBCPP_TEMPLATE_VIS tuple_element<_Ip, __tuple_types<_Types...> > {
  45   static_assert(_Ip < sizeof...(_Types), "tuple_element index out of range");
  46   typedef _LIBCPP_NODEBUG __type_pack_element<_Ip, _Types...> type;
  47 };
  48
  49 #  if _LIBCPP_STD_VER >= 14
  50 template <size_t _Ip, class... _Tp>
  51 using tuple_element_t _LIBCPP_NODEBUG = typename tuple_element<_Ip, _Tp...>::type;
  52 #  endif
  53
  54 #endif // _LIBCPP_CXX03_LANG
  55
  56 _LIBCPP_END_NAMESPACE_STD
  57
  58 #endif // _LIBCPP___TUPLE_TUPLE_ELEMENT_H