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 #ifndef _LIBCPP___RANGES_COUNTED_H 10 #define _LIBCPP___RANGES_COUNTED_H 11 12 #include <__concepts/convertible_to.h> 13 #include <__config> 14 #include <__iterator/concepts.h> 15 #include <__iterator/counted_iterator.h> 16 #include <__iterator/default_sentinel.h> 17 #include <__iterator/incrementable_traits.h> 18 #include <__iterator/iterator_traits.h> 19 #include <__memory/pointer_traits.h> 20 #include <__ranges/subrange.h> 21 #include <__utility/forward.h> 22 #include <__utility/move.h> 23 #include <span> 24 #include <type_traits> 25 26 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 27 # pragma GCC system_header 28 #endif 29 30 _LIBCPP_BEGIN_NAMESPACE_STD 31 32 #if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES) 33 34 namespace ranges::views { 35 36 namespace __counted { 37 38 struct __fn { 39 template<contiguous_iterator _It> 40 _LIBCPP_HIDE_FROM_ABI 41 static constexpr auto __go(_It __it, iter_difference_t<_It> __count) 42 noexcept(noexcept(span(std::to_address(__it), static_cast<size_t>(__count)))) 43 // Deliberately omit return-type SFINAE, because to_address is not SFINAE-friendly 44 { return span(std::to_address(__it), static_cast<size_t>(__count)); } 45 46 template<random_access_iterator _It> 47 _LIBCPP_HIDE_FROM_ABI 48 static constexpr auto __go(_It __it, iter_difference_t<_It> __count) 49 noexcept(noexcept(subrange(__it, __it + __count))) 50 -> decltype( subrange(__it, __it + __count)) 51 { return subrange(__it, __it + __count); } 52 53 template<class _It> 54 _LIBCPP_HIDE_FROM_ABI 55 static constexpr auto __go(_It __it, iter_difference_t<_It> __count) 56 noexcept(noexcept(subrange(counted_iterator(std::move(__it), __count), default_sentinel))) 57 -> decltype( subrange(counted_iterator(std::move(__it), __count), default_sentinel)) 58 { return subrange(counted_iterator(std::move(__it), __count), default_sentinel); } 59 60 template<class _It, convertible_to<iter_difference_t<_It>> _Diff> 61 requires input_or_output_iterator<decay_t<_It>> 62 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI 63 constexpr auto operator()(_It&& __it, _Diff&& __count) const 64 noexcept(noexcept(__go(std::forward<_It>(__it), std::forward<_Diff>(__count)))) 65 -> decltype( __go(std::forward<_It>(__it), std::forward<_Diff>(__count))) 66 { return __go(std::forward<_It>(__it), std::forward<_Diff>(__count)); } 67 }; 68 69 } // namespace __counted 70 71 inline namespace __cpo { 72 inline constexpr auto counted = __counted::__fn{}; 73 } // namespace __cpo 74 75 } // namespace ranges::views 76 77 #endif // _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES) 78 79 _LIBCPP_END_NAMESPACE_STD 80 81 #endif // _LIBCPP___RANGES_COUNTED_H 82