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, __enable_if_t<__has_input_iterator_category<_InputIter>::value, int> = 0> 28 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 _InputIter 29 next(_InputIter __x, typename iterator_traits<_InputIter>::difference_type __n = 1) { 30 // Calling `advance` with a negative value on a non-bidirectional iterator is a no-op in the current implementation. 31 // Note that this check duplicates the similar check in `std::advance`. 32 _LIBCPP_ASSERT_PEDANTIC(__n >= 0 || __has_bidirectional_iterator_category<_InputIter>::value, 33 "Attempt to next(it, n) with negative n on a non-bidirectional iterator"); 34 35 std::advance(__x, __n); 36 return __x; 37 } 38 39 #if _LIBCPP_STD_VER >= 20 40 41 // [range.iter.op.next] 42 43 namespace ranges { 44 namespace __next { 45 46 struct __fn { 47 template <input_or_output_iterator _Ip> 48 _LIBCPP_HIDE_FROM_ABI 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 constexpr _Ip operator()(_Ip __x, iter_difference_t<_Ip> __n) const { 55 ranges::advance(__x, __n); 56 return __x; 57 } 58 59 template <input_or_output_iterator _Ip, sentinel_for<_Ip> _Sp> 60 _LIBCPP_HIDE_FROM_ABI constexpr _Ip operator()(_Ip __x, _Sp __bound_sentinel) const { 61 ranges::advance(__x, __bound_sentinel); 62 return __x; 63 } 64 65 template <input_or_output_iterator _Ip, sentinel_for<_Ip> _Sp> 66 _LIBCPP_HIDE_FROM_ABI constexpr _Ip operator()(_Ip __x, iter_difference_t<_Ip> __n, _Sp __bound_sentinel) const { 67 ranges::advance(__x, __n, __bound_sentinel); 68 return __x; 69 } 70 }; 71 72 } // namespace __next 73 74 inline namespace __cpo { 75 inline constexpr auto next = __next::__fn{}; 76 } // namespace __cpo 77 } // namespace ranges 78 79 #endif // _LIBCPP_STD_VER >= 20 80 81 _LIBCPP_END_NAMESPACE_STD 82 83 #endif // _LIBCPP___ITERATOR_NEXT_H 84