1 // -*- C++ -*- 2 //===----------------------------------------------------------------------===// 3 // 4 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 5 // See https://llvm.org/LICENSE.txt for license information. 6 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 7 // 8 //===----------------------------------------------------------------------===// 9 10 #ifndef _LIBCPP___ITERATOR_NEXT_H 11 #define _LIBCPP___ITERATOR_NEXT_H 12 13 #include <__assert> 14 #include <__config> 15 #include <__iterator/advance.h> 16 #include <__iterator/concepts.h> 17 #include <__iterator/incrementable_traits.h> 18 #include <__iterator/iterator_traits.h> 19 #include <__type_traits/enable_if.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 _InputIter> 28 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX17 29 typename enable_if<__has_input_iterator_category<_InputIter>::value, _InputIter>::type 30 next(_InputIter __x, typename iterator_traits<_InputIter>::difference_type __n = 1) { 31 _LIBCPP_ASSERT_UNCATEGORIZED(__n >= 0 || __has_bidirectional_iterator_category<_InputIter>::value, 32 "Attempt to next(it, n) with negative n on a non-bidirectional iterator"); 33 34 _VSTD::advance(__x, __n); 35 return __x; 36 } 37 38 #if _LIBCPP_STD_VER >= 20 39 40 // [range.iter.op.next] 41 42 namespace ranges { 43 namespace __next { 44 45 struct __fn { 46 template <input_or_output_iterator _Ip> 47 _LIBCPP_HIDE_FROM_ABI 48 constexpr _Ip operator()(_Ip __x) const { 49 ++__x; 50 return __x; 51 } 52 53 template <input_or_output_iterator _Ip> 54 _LIBCPP_HIDE_FROM_ABI 55 constexpr _Ip operator()(_Ip __x, iter_difference_t<_Ip> __n) const { 56 ranges::advance(__x, __n); 57 return __x; 58 } 59 60 template <input_or_output_iterator _Ip, sentinel_for<_Ip> _Sp> 61 _LIBCPP_HIDE_FROM_ABI constexpr _Ip operator()(_Ip __x, _Sp __bound_sentinel) const { 62 ranges::advance(__x, __bound_sentinel); 63 return __x; 64 } 65 66 template <input_or_output_iterator _Ip, sentinel_for<_Ip> _Sp> 67 _LIBCPP_HIDE_FROM_ABI constexpr _Ip operator()(_Ip __x, iter_difference_t<_Ip> __n, _Sp __bound_sentinel) const { 68 ranges::advance(__x, __n, __bound_sentinel); 69 return __x; 70 } 71 }; 72 73 } // namespace __next 74 75 inline namespace __cpo { 76 inline constexpr auto next = __next::__fn{}; 77 } // namespace __cpo 78 } // namespace ranges 79 80 #endif // _LIBCPP_STD_VER >= 20 81 82 _LIBCPP_END_NAMESPACE_STD 83 84 #endif // _LIBCPP___ITERATOR_NEXT_H 85