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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-exception6//7//===----------------------------------------------------------------------===//8 9#ifndef _LIBCPP___ALGORITHM_RANGES_MINMAX_H10#define _LIBCPP___ALGORITHM_RANGES_MINMAX_H11 12#include <__algorithm/min_max_result.h>13#include <__algorithm/minmax_element.h>14#include <__assert>15#include <__concepts/copyable.h>16#include <__concepts/same_as.h>17#include <__config>18#include <__functional/identity.h>19#include <__functional/invoke.h>20#include <__functional/ranges_operations.h>21#include <__iterator/concepts.h>22#include <__iterator/next.h>23#include <__iterator/projected.h>24#include <__ranges/access.h>25#include <__ranges/concepts.h>26#include <__type_traits/desugars_to.h>27#include <__type_traits/is_integral.h>28#include <__type_traits/is_reference.h>29#include <__type_traits/is_trivially_copyable.h>30#include <__type_traits/remove_cvref.h>31#include <__utility/forward.h>32#include <__utility/move.h>33#include <__utility/pair.h>34#include <initializer_list>35 36#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)37# pragma GCC system_header38#endif39 40#if _LIBCPP_STD_VER >= 2041 42_LIBCPP_PUSH_MACROS43# include <__undef_macros>44 45_LIBCPP_BEGIN_NAMESPACE_STD46 47namespace ranges {48template <class _T1>49using minmax_result = min_max_result<_T1>;50 51struct __minmax {52 template <class _Type,53 class _Proj = identity,54 indirect_strict_weak_order<projected<const _Type*, _Proj>> _Comp = ranges::less>55 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr ranges::minmax_result<const _Type&>56 operator()(_LIBCPP_LIFETIMEBOUND const _Type& __a,57 _LIBCPP_LIFETIMEBOUND const _Type& __b,58 _Comp __comp = {},59 _Proj __proj = {}) const {60 if (std::invoke(__comp, std::invoke(__proj, __b), std::invoke(__proj, __a)))61 return {__b, __a};62 return {__a, __b};63 }64 65 template <copyable _Type,66 class _Proj = identity,67 indirect_strict_weak_order<projected<const _Type*, _Proj>> _Comp = ranges::less>68 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr ranges::minmax_result<_Type>69 operator()(initializer_list<_Type> __il, _Comp __comp = {}, _Proj __proj = {}) const {70 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(71 __il.begin() != __il.end(), "initializer_list has to contain at least one element");72 auto __iters = std::__minmax_element_impl(__il.begin(), __il.end(), __comp, __proj);73 return ranges::minmax_result<_Type>{*__iters.first, *__iters.second};74 }75 76 template <input_range _Range,77 class _Proj = identity,78 indirect_strict_weak_order<projected<iterator_t<_Range>, _Proj>> _Comp = ranges::less>79 requires indirectly_copyable_storable<iterator_t<_Range>, range_value_t<_Range>*>80 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr ranges::minmax_result<range_value_t<_Range>>81 operator()(_Range&& __r, _Comp __comp = {}, _Proj __proj = {}) const {82 auto __first = ranges::begin(__r);83 auto __last = ranges::end(__r);84 using _ValueT = range_value_t<_Range>;85 86 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__first != __last, "range has to contain at least one element");87 88 // This optimiation is not in minmax_element because clang doesn't see through the pointers and as a result doesn't89 // vectorize the code.90 if constexpr (contiguous_range<_Range> && is_integral_v<_ValueT> &&91 __is_cheap_to_copy<_ValueT> & __is_identity<_Proj>::value &&92 __desugars_to_v<__less_tag, _Comp, _ValueT, _ValueT>) {93 minmax_result<_ValueT> __result = {__r[0], __r[0]};94 for (auto __e : __r) {95 if (__e < __result.min)96 __result.min = __e;97 if (__result.max < __e)98 __result.max = __e;99 }100 return __result;101 } else if constexpr (forward_range<_Range>) {102 // Special-case the one element case. Avoid repeatedly initializing objects from the result of an iterator103 // dereference when doing so might not be idempotent. The `if constexpr` avoids the extra branch in cases where104 // it's not needed.105 if constexpr (!same_as<remove_cvref_t<range_reference_t<_Range>>, _ValueT> ||106 is_rvalue_reference_v<range_reference_t<_Range>>) {107 if (ranges::next(__first) == __last) {108 // During initialization, members are allowed to refer to already initialized members109 // (see http://eel.is/c++draft/dcl.init.aggr#6)110 minmax_result<_ValueT> __result = {*__first, __result.min};111 return __result;112 }113 }114 auto __result = std::__minmax_element_impl(__first, __last, __comp, __proj);115 return {*__result.first, *__result.second};116 } else {117 // input_iterators can't be copied, so the implementation for input_iterators has to store118 // the values instead of a pointer to the correct values119 auto __less = [&](auto&& __a, auto&& __b) -> bool {120 return std::invoke(__comp,121 std::invoke(__proj, std::forward<decltype(__a)>(__a)),122 std::invoke(__proj, std::forward<decltype(__b)>(__b)));123 };124 125 // During initialization, members are allowed to refer to already initialized members126 // (see http://eel.is/c++draft/dcl.init.aggr#6)127 ranges::minmax_result<_ValueT> __result = {*__first, __result.min};128 if (__first == __last || ++__first == __last)129 return __result;130 131 if (__less(*__first, __result.min))132 __result.min = *__first;133 else134 __result.max = *__first;135 136 while (++__first != __last) {137 _ValueT __i = *__first;138 if (++__first == __last) {139 if (__less(__i, __result.min))140 __result.min = __i;141 else if (!__less(__i, __result.max))142 __result.max = __i;143 return __result;144 }145 146 if (__less(*__first, __i)) {147 if (__less(*__first, __result.min))148 __result.min = *__first;149 if (!__less(__i, __result.max))150 __result.max = std::move(__i);151 } else {152 if (__less(__i, __result.min))153 __result.min = std::move(__i);154 if (!__less(*__first, __result.max))155 __result.max = *__first;156 }157 }158 return __result;159 }160 }161};162 163inline namespace __cpo {164inline constexpr auto minmax = __minmax{};165} // namespace __cpo166} // namespace ranges167 168_LIBCPP_END_NAMESPACE_STD169 170_LIBCPP_POP_MACROS171 172#endif // _LIBCPP_STD_VER >= 20173 174#endif // _LIBCPP___ALGORITHM_RANGES_MINMAX_H175