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