1 //===----------------------------------------------------------------------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 #ifndef _LIBCPP___ALGORITHM_RANGES_PARTITION_POINT_H 10 #define _LIBCPP___ALGORITHM_RANGES_PARTITION_POINT_H 11 12 #include <__algorithm/half_positive.h> 13 #include <__config> 14 #include <__functional/identity.h> 15 #include <__functional/invoke.h> 16 #include <__iterator/concepts.h> 17 #include <__iterator/distance.h> 18 #include <__iterator/iterator_traits.h> 19 #include <__iterator/next.h> 20 #include <__iterator/projected.h> 21 #include <__ranges/access.h> 22 #include <__ranges/concepts.h> 23 #include <__ranges/dangling.h> 24 #include <__utility/move.h> 25 26 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 27 # pragma GCC system_header 28 #endif 29 30 _LIBCPP_PUSH_MACROS 31 #include <__undef_macros> 32 33 #if _LIBCPP_STD_VER >= 20 34 35 _LIBCPP_BEGIN_NAMESPACE_STD 36 37 namespace ranges { 38 struct __partition_point { 39 // TODO(ranges): delegate to the classic algorithm. 40 template <class _Iter, class _Sent, class _Proj, class _Pred> 41 _LIBCPP_HIDE_FROM_ABI constexpr static _Iter 42 __partition_point_fn_impl(_Iter&& __first, _Sent&& __last, _Pred& __pred, _Proj& __proj) { 43 auto __len = ranges::distance(__first, __last); 44 45 while (__len != 0) { 46 auto __half_len = std::__half_positive(__len); 47 auto __mid = ranges::next(__first, __half_len); 48 49 if (std::invoke(__pred, std::invoke(__proj, *__mid))) { 50 __first = ++__mid; 51 __len -= __half_len + 1; 52 53 } else { 54 __len = __half_len; 55 } 56 } 57 58 return __first; 59 } 60 61 template <forward_iterator _Iter, 62 sentinel_for<_Iter> _Sent, 63 class _Proj = identity, 64 indirect_unary_predicate<projected<_Iter, _Proj>> _Pred> 65 _LIBCPP_HIDE_FROM_ABI constexpr _Iter operator()(_Iter __first, _Sent __last, _Pred __pred, _Proj __proj = {}) const { 66 return __partition_point_fn_impl(std::move(__first), std::move(__last), __pred, __proj); 67 } 68 69 template <forward_range _Range, 70 class _Proj = identity, 71 indirect_unary_predicate<projected<iterator_t<_Range>, _Proj>> _Pred> 72 _LIBCPP_HIDE_FROM_ABI constexpr borrowed_iterator_t<_Range> 73 operator()(_Range&& __range, _Pred __pred, _Proj __proj = {}) const { 74 return __partition_point_fn_impl(ranges::begin(__range), ranges::end(__range), __pred, __proj); 75 } 76 }; 77 78 inline namespace __cpo { 79 inline constexpr auto partition_point = __partition_point{}; 80 } // namespace __cpo 81 } // namespace ranges 82 83 _LIBCPP_END_NAMESPACE_STD 84 85 #endif // _LIBCPP_STD_VER >= 20 86 87 _LIBCPP_POP_MACROS 88 89 #endif // _LIBCPP___ALGORITHM_RANGES_PARTITION_POINT_H 90