90 lines · c
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-exception7//8//===----------------------------------------------------------------------===//9 10#ifndef _LIBCPP___RANGES_COUNTED_H11#define _LIBCPP___RANGES_COUNTED_H12 13#include <__concepts/convertible_to.h>14#include <__config>15#include <__cstddef/size_t.h>16#include <__iterator/concepts.h>17#include <__iterator/counted_iterator.h>18#include <__iterator/default_sentinel.h>19#include <__iterator/incrementable_traits.h>20#include <__iterator/iterator_traits.h>21#include <__memory/pointer_traits.h>22#include <__ranges/subrange.h>23#include <__type_traits/decay.h>24#include <__utility/forward.h>25#include <__utility/move.h>26#include <span>27 28#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)29# pragma GCC system_header30#endif31 32_LIBCPP_PUSH_MACROS33#include <__undef_macros>34 35_LIBCPP_BEGIN_NAMESPACE_STD36 37#if _LIBCPP_STD_VER >= 2038 39namespace ranges::views {40 41namespace __counted {42 43struct __fn {44 template <contiguous_iterator _It>45 _LIBCPP_HIDE_FROM_ABI static constexpr auto46 __go(_It __it,47 iter_difference_t<_It> __count) noexcept(noexcept(span(std::to_address(__it), static_cast<size_t>(__count))))48 // Deliberately omit return-type SFINAE, because to_address is not SFINAE-friendly49 {50 return span(std::to_address(__it), static_cast<size_t>(__count));51 }52 53 template <random_access_iterator _It>54 _LIBCPP_HIDE_FROM_ABI static constexpr auto __go(_It __it, iter_difference_t<_It> __count) noexcept(55 noexcept(subrange(__it, __it + __count))) -> decltype(subrange(__it, __it + __count)) {56 return subrange(__it, __it + __count);57 }58 59 template <class _It>60 _LIBCPP_HIDE_FROM_ABI static constexpr auto __go(_It __it, iter_difference_t<_It> __count) noexcept(61 noexcept(subrange(counted_iterator(std::move(__it), __count), default_sentinel)))62 -> decltype(subrange(counted_iterator(std::move(__it), __count), default_sentinel)) {63 return subrange(counted_iterator(std::move(__it), __count), default_sentinel);64 }65 66 template <class _It, convertible_to<iter_difference_t<_It>> _Diff>67 requires input_or_output_iterator<decay_t<_It>>68 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_It&& __it, _Diff&& __count) const69 noexcept(noexcept(__go(std::forward<_It>(__it), std::forward<_Diff>(__count))))70 -> decltype(__go(std::forward<_It>(__it), std::forward<_Diff>(__count))) {71 return __go(std::forward<_It>(__it), std::forward<_Diff>(__count));72 }73};74 75} // namespace __counted76 77inline namespace __cpo {78inline constexpr auto counted = __counted::__fn{};79} // namespace __cpo80 81} // namespace ranges::views82 83#endif // _LIBCPP_STD_VER >= 2084 85_LIBCPP_END_NAMESPACE_STD86 87_LIBCPP_POP_MACROS88 89#endif // _LIBCPP___RANGES_COUNTED_H90