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_MINMAX_H 10 #define _LIBCPP___ALGORITHM_RANGES_MINMAX_H 11 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_reference.h> 28 #include <__type_traits/is_trivially_copyable.h> 29 #include <__type_traits/remove_cvref.h> 30 #include <__utility/forward.h> 31 #include <__utility/move.h> 32 #include <__utility/pair.h> 33 #include <initializer_list> 34 35 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 36 # pragma GCC system_header 37 #endif 38 39 #if _LIBCPP_STD_VER >= 20 40 41 _LIBCPP_PUSH_MACROS 42 # include <__undef_macros> 43 44 _LIBCPP_BEGIN_NAMESPACE_STD 45 46 namespace ranges { 47 template <class _T1> 48 using minmax_result = min_max_result<_T1>; 49 50 namespace __minmax { 51 struct __fn { 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&> operator__fn56 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> operator__fn69 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>> operator__fn81 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't 89 // 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 iterator 103 // dereference when doing so might not be idempotent. The `if constexpr` avoids the extra branch in cases where 104 // 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 members 109 // (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 store 118 // the values instead of a pointer to the correct values 119 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 members 126 // (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 else 134 __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 } // namespace __minmax 163 164 inline namespace __cpo { 165 inline constexpr auto minmax = __minmax::__fn{}; 166 } // namespace __cpo 167 } // namespace ranges 168 169 _LIBCPP_END_NAMESPACE_STD 170 171 _LIBCPP_POP_MACROS 172 173 #endif // _LIBCPP_STD_VER >= 20 174 175 #endif // _LIBCPP___ALGORITHM_RANGES_MINMAX_H 176