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_PUSH_MACROS 27 #include <__undef_macros> 28 29 _LIBCPP_BEGIN_NAMESPACE_STD 30 31 template <class _InputIter> 32 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14 33 typename enable_if<__is_cpp17_input_iterator<_InputIter>::value, _InputIter>::type 34 next(_InputIter __x, typename iterator_traits<_InputIter>::difference_type __n = 1) { 35 _LIBCPP_ASSERT(__n >= 0 || __is_cpp17_bidirectional_iterator<_InputIter>::value, 36 "Attempt to next(it, n) with negative n on a non-bidirectional iterator"); 37 38 _VSTD::advance(__x, __n); 39 return __x; 40 } 41 42 #if !defined(_LIBCPP_HAS_NO_RANGES) 43 44 namespace ranges { 45 struct __next_fn final : private __function_like { 46 constexpr explicit __next_fn(__tag __x) noexcept : __function_like(__x) {} 47 48 template <input_or_output_iterator _Ip> 49 constexpr _Ip operator()(_Ip __x) const { 50 ++__x; 51 return __x; 52 } 53 54 template <input_or_output_iterator _Ip> 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 constexpr _Ip operator()(_Ip __x, _Sp __bound) const { 62 ranges::advance(__x, __bound); 63 return __x; 64 } 65 66 template <input_or_output_iterator _Ip, sentinel_for<_Ip> _Sp> 67 constexpr _Ip operator()(_Ip __x, iter_difference_t<_Ip> __n, _Sp __bound) const { 68 ranges::advance(__x, __n, __bound); 69 return __x; 70 } 71 }; 72 73 inline constexpr auto next = __next_fn(__function_like::__tag()); 74 } // namespace ranges 75 76 #endif // !defined(_LIBCPP_HAS_NO_RANGES) 77 78 _LIBCPP_END_NAMESPACE_STD 79 80 _LIBCPP_POP_MACROS 81 82 #endif // _LIBCPP___ITERATOR_PRIMITIVES_H 83