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___RANGES_COUNTED_H 11 #define _LIBCPP___RANGES_COUNTED_H 12 13 #include <__concepts/convertible_to.h> 14 #include <__config> 15 #include <__iterator/concepts.h> 16 #include <__iterator/counted_iterator.h> 17 #include <__iterator/default_sentinel.h> 18 #include <__iterator/incrementable_traits.h> 19 #include <__iterator/iterator_traits.h> 20 #include <__memory/pointer_traits.h> 21 #include <__ranges/subrange.h> 22 #include <__type_traits/decay.h> 23 #include <__utility/forward.h> 24 #include <__utility/move.h> 25 #include <cstddef> 26 #include <span> 27 28 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 29 # pragma GCC system_header 30 #endif 31 32 _LIBCPP_BEGIN_NAMESPACE_STD 33 34 #if _LIBCPP_STD_VER >= 20 35 36 namespace ranges::views { 37 38 namespace __counted { 39 40 struct __fn { 41 template<contiguous_iterator _It> 42 _LIBCPP_HIDE_FROM_ABI 43 static constexpr auto __go(_It __it, iter_difference_t<_It> __count) 44 noexcept(noexcept(span(std::to_address(__it), static_cast<size_t>(__count)))) 45 // Deliberately omit return-type SFINAE, because to_address is not SFINAE-friendly 46 { return span(std::to_address(__it), static_cast<size_t>(__count)); } 47 48 template<random_access_iterator _It> 49 _LIBCPP_HIDE_FROM_ABI 50 static constexpr auto __go(_It __it, iter_difference_t<_It> __count) 51 noexcept(noexcept(subrange(__it, __it + __count))) 52 -> decltype( subrange(__it, __it + __count)) 53 { return subrange(__it, __it + __count); } 54 55 template<class _It> 56 _LIBCPP_HIDE_FROM_ABI 57 static constexpr auto __go(_It __it, iter_difference_t<_It> __count) 58 noexcept(noexcept(subrange(counted_iterator(std::move(__it), __count), default_sentinel))) 59 -> decltype( subrange(counted_iterator(std::move(__it), __count), default_sentinel)) 60 { return subrange(counted_iterator(std::move(__it), __count), default_sentinel); } 61 62 template<class _It, convertible_to<iter_difference_t<_It>> _Diff> 63 requires input_or_output_iterator<decay_t<_It>> 64 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI 65 constexpr auto operator()(_It&& __it, _Diff&& __count) const 66 noexcept(noexcept(__go(std::forward<_It>(__it), std::forward<_Diff>(__count)))) 67 -> decltype( __go(std::forward<_It>(__it), std::forward<_Diff>(__count))) 68 { return __go(std::forward<_It>(__it), std::forward<_Diff>(__count)); } 69 }; 70 71 } // namespace __counted 72 73 inline namespace __cpo { 74 inline constexpr auto counted = __counted::__fn{}; 75 } // namespace __cpo 76 77 } // namespace ranges::views 78 79 #endif // _LIBCPP_STD_VER >= 20 80 81 _LIBCPP_END_NAMESPACE_STD 82 83 #endif // _LIBCPP___RANGES_COUNTED_H 84