v1/__algorithm/ranges_min_element.h

0001 //===----------------------------------------------------------------------===//
0002 //
0003 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
0004 // See https://llvm.org/LICENSE.txt for license information.
0005 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
0006 //
0007 //===----------------------------------------------------------------------===//
0008
0009 #ifndef _LIBCPP___ALGORITHM_RANGES_MIN_ELEMENT_H
0010 #define _LIBCPP___ALGORITHM_RANGES_MIN_ELEMENT_H
0011
0012 #include <__config>
0013 #include <__functional/identity.h>
0014 #include <__functional/invoke.h>
0015 #include <__functional/ranges_operations.h>
0016 #include <__iterator/concepts.h>
0017 #include <__iterator/projected.h>
0018 #include <__ranges/access.h>
0019 #include <__ranges/concepts.h>
0020 #include <__ranges/dangling.h>
0021 #include <__utility/forward.h>
0022
0023 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
0024 #  pragma GCC system_header
0025 #endif
0026
0027 _LIBCPP_PUSH_MACROS
0028 #include <__undef_macros>
0029
0030 #if _LIBCPP_STD_VER >= 20
0031
0032 _LIBCPP_BEGIN_NAMESPACE_STD
0033
0034 namespace ranges {
0035
0036 // TODO(ranges): `ranges::min_element` can now simply delegate to `std::__min_element`.
0037 template <class _Ip, class _Sp, class _Proj, class _Comp>
0038 _LIBCPP_HIDE_FROM_ABI constexpr _Ip __min_element_impl(_Ip __first, _Sp __last, _Comp& __comp, _Proj& __proj) {
0039   if (__first == __last)
0040     return __first;
0041
0042   _Ip __i = __first;
0043   while (++__i != __last)
0044     if (std::invoke(__comp, std::invoke(__proj, *__i), std::invoke(__proj, *__first)))
0045       __first = __i;
0046   return __first;
0047 }
0048
0049 struct __min_element {
0050   template <forward_iterator _Ip,
0051             sentinel_for<_Ip> _Sp,
0052             class _Proj                                             = identity,
0053             indirect_strict_weak_order<projected<_Ip, _Proj>> _Comp = ranges::less>
0054   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr _Ip
0055   operator()(_Ip __first, _Sp __last, _Comp __comp = {}, _Proj __proj = {}) const {
0056     return ranges::__min_element_impl(__first, __last, __comp, __proj);
0057   }
0058
0059   template <forward_range _Rp,
0060             class _Proj                                                         = identity,
0061             indirect_strict_weak_order<projected<iterator_t<_Rp>, _Proj>> _Comp = ranges::less>
0062   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr borrowed_iterator_t<_Rp>
0063   operator()(_Rp&& __r, _Comp __comp = {}, _Proj __proj = {}) const {
0064     return ranges::__min_element_impl(ranges::begin(__r), ranges::end(__r), __comp, __proj);
0065   }
0066 };
0067
0068 inline namespace __cpo {
0069 inline constexpr auto min_element = __min_element{};
0070 } // namespace __cpo
0071 } // namespace ranges
0072
0073 _LIBCPP_END_NAMESPACE_STD
0074
0075 #endif // _LIBCPP_STD_VER >= 20
0076
0077 _LIBCPP_POP_MACROS
0078
0079 #endif // _LIBCPP___ALGORITHM_RANGES_MIN_ELEMENT_H