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 <__config> 14 #include <__debug> 15 #include <__function_like.h> 16 #include <__iterator/advance.h> 17 #include <__iterator/concepts.h> 18 #include <__iterator/incrementable_traits.h> 19 #include <__iterator/iterator_traits.h> 20 #include <type_traits> 21 22 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 23 #pragma GCC system_header 24 #endif 25 26 _LIBCPP_BEGIN_NAMESPACE_STD 27 28 template <class _InputIter> 29 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14 30 typename enable_if<__is_cpp17_input_iterator<_InputIter>::value, _InputIter>::type 31 next(_InputIter __x, typename iterator_traits<_InputIter>::difference_type __n = 1) { 32 _LIBCPP_ASSERT(__n >= 0 || __is_cpp17_bidirectional_iterator<_InputIter>::value, 33 "Attempt to next(it, n) with negative n on a non-bidirectional iterator"); 34 35 _VSTD::advance(__x, __n); 36 return __x; 37 } 38 39 #if !defined(_LIBCPP_HAS_NO_RANGES) 40 41 namespace ranges { 42 struct __next_fn final : private __function_like { 43 _LIBCPP_HIDE_FROM_ABI 44 constexpr explicit __next_fn(__tag __x) noexcept : __function_like(__x) {} 45 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 62 constexpr _Ip operator()(_Ip __x, _Sp __bound) const { 63 ranges::advance(__x, __bound); 64 return __x; 65 } 66 67 template <input_or_output_iterator _Ip, sentinel_for<_Ip> _Sp> 68 _LIBCPP_HIDE_FROM_ABI 69 constexpr _Ip operator()(_Ip __x, iter_difference_t<_Ip> __n, _Sp __bound) const { 70 ranges::advance(__x, __n, __bound); 71 return __x; 72 } 73 }; 74 75 inline constexpr auto next = __next_fn(__function_like::__tag()); 76 } // namespace ranges 77 78 #endif // !defined(_LIBCPP_HAS_NO_RANGES) 79 80 _LIBCPP_END_NAMESPACE_STD 81 82 #endif // _LIBCPP___ITERATOR_PRIMITIVES_H 83