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___ALGORITHM_RANGES_FOR_EACH_N_H 10 #define _LIBCPP___ALGORITHM_RANGES_FOR_EACH_N_H 11 12 #include <__algorithm/in_fun_result.h> 13 #include <__config> 14 #include <__functional/identity.h> 15 #include <__functional/invoke.h> 16 #include <__iterator/concepts.h> 17 #include <__iterator/incrementable_traits.h> 18 #include <__iterator/iterator_traits.h> 19 #include <__iterator/projected.h> 20 #include <__ranges/concepts.h> 21 #include <__utility/move.h> 22 23 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 24 # pragma GCC system_header 25 #endif 26 27 _LIBCPP_PUSH_MACROS 28 #include <__undef_macros> 29 30 #if _LIBCPP_STD_VER >= 20 31 32 _LIBCPP_BEGIN_NAMESPACE_STD 33 34 namespace ranges { 35 36 template <class _Iter, class _Func> 37 using for_each_n_result = in_fun_result<_Iter, _Func>; 38 39 namespace __for_each_n { 40 struct __fn { 41 template <input_iterator _Iter, class _Proj = identity, indirectly_unary_invocable<projected<_Iter, _Proj>> _Func> 42 _LIBCPP_HIDE_FROM_ABI constexpr for_each_n_result<_Iter, _Func> 43 operator()(_Iter __first, iter_difference_t<_Iter> __count, _Func __func, _Proj __proj = {}) const { 44 while (__count-- > 0) { 45 std::invoke(__func, std::invoke(__proj, *__first)); 46 ++__first; 47 } 48 return {std::move(__first), std::move(__func)}; 49 } 50 }; 51 } // namespace __for_each_n 52 53 inline namespace __cpo { 54 inline constexpr auto for_each_n = __for_each_n::__fn{}; 55 } // namespace __cpo 56 } // namespace ranges 57 58 _LIBCPP_END_NAMESPACE_STD 59 60 #endif // _LIBCPP_STD_VER >= 20 61 62 _LIBCPP_POP_MACROS 63 64 #endif // _LIBCPP___ALGORITHM_RANGES_FOR_EACH_N_H 65