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_PUSH_MACROS 33 #include <__undef_macros> 34 35 _LIBCPP_BEGIN_NAMESPACE_STD 36 37 #if _LIBCPP_STD_VER >= 20 38 39 namespace ranges::views { 40 41 namespace __counted { 42 43 struct __fn { 44 template <contiguous_iterator _It> 45 _LIBCPP_HIDE_FROM_ABI static constexpr auto 46 __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-friendly 49 { 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) const 69 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 __counted 76 77 inline namespace __cpo { 78 inline constexpr auto counted = __counted::__fn{}; 79 } // namespace __cpo 80 81 } // namespace ranges::views 82 83 #endif // _LIBCPP_STD_VER >= 20 84 85 _LIBCPP_END_NAMESPACE_STD 86 87 _LIBCPP_POP_MACROS 88 89 #endif // _LIBCPP___RANGES_COUNTED_H 90