xref: /llvm-project/libcxx/include/__tuple/tuple_size.h (revision f69585235ec85d54e0f3fc41b2d5700430907f99)
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 _LIBCPP_NODEBUG = _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
78