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 struct __minmax { 51 template <class _Type, 52 class _Proj = identity, 53 indirect_strict_weak_order<projected<const _Type*, _Proj>> _Comp = ranges::less> 54 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr ranges::minmax_result<const _Type&> 55 operator()(_LIBCPP_LIFETIMEBOUND const _Type& __a, 56 _LIBCPP_LIFETIMEBOUND const _Type& __b, 57 _Comp __comp = {}, 58 _Proj __proj = {}) const { 59 if (std::invoke(__comp, std::invoke(__proj, __b), std::invoke(__proj, __a))) 60 return {__b, __a}; 61 return {__a, __b}; 62 } 63 64 template <copyable _Type, 65 class _Proj = identity, 66 indirect_strict_weak_order<projected<const _Type*, _Proj>> _Comp = ranges::less> 67 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr ranges::minmax_result<_Type> 68 operator()(initializer_list<_Type> __il, _Comp __comp = {}, _Proj __proj = {}) const { 69 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS( 70 __il.begin() != __il.end(), "initializer_list has to contain at least one element"); 71 auto __iters = std::__minmax_element_impl(__il.begin(), __il.end(), __comp, __proj); 72 return ranges::minmax_result<_Type>{*__iters.first, *__iters.second}; 73 } 74 75 template <input_range _Range, 76 class _Proj = identity, 77 indirect_strict_weak_order<projected<iterator_t<_Range>, _Proj>> _Comp = ranges::less> 78 requires indirectly_copyable_storable<iterator_t<_Range>, range_value_t<_Range>*> 79 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr ranges::minmax_result<range_value_t<_Range>> 80 operator()(_Range&& __r, _Comp __comp = {}, _Proj __proj = {}) const { 81 auto __first = ranges::begin(__r); 82 auto __last = ranges::end(__r); 83 using _ValueT = range_value_t<_Range>; 84 85 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__first != __last, "range has to contain at least one element"); 86 87 // This optimiation is not in minmax_element because clang doesn't see through the pointers and as a result doesn't 88 // vectorize the code. 89 if constexpr (contiguous_range<_Range> && is_integral_v<_ValueT> && 90 __is_cheap_to_copy<_ValueT> & __is_identity<_Proj>::value && 91 __desugars_to_v<__less_tag, _Comp, _ValueT, _ValueT>) { 92 minmax_result<_ValueT> __result = {__r[0], __r[0]}; 93 for (auto __e : __r) { 94 if (__e < __result.min) 95 __result.min = __e; 96 if (__result.max < __e) 97 __result.max = __e; 98 } 99 return __result; 100 } else if constexpr (forward_range<_Range>) { 101 // Special-case the one element case. Avoid repeatedly initializing objects from the result of an iterator 102 // dereference when doing so might not be idempotent. The `if constexpr` avoids the extra branch in cases where 103 // it's not needed. 104 if constexpr (!same_as<remove_cvref_t<range_reference_t<_Range>>, _ValueT> || 105 is_rvalue_reference_v<range_reference_t<_Range>>) { 106 if (ranges::next(__first) == __last) { 107 // During initialization, members are allowed to refer to already initialized members 108 // (see http://eel.is/c++draft/dcl.init.aggr#6) 109 minmax_result<_ValueT> __result = {*__first, __result.min}; 110 return __result; 111 } 112 } 113 auto __result = std::__minmax_element_impl(__first, __last, __comp, __proj); 114 return {*__result.first, *__result.second}; 115 } else { 116 // input_iterators can't be copied, so the implementation for input_iterators has to store 117 // the values instead of a pointer to the correct values 118 auto __less = [&](auto&& __a, auto&& __b) -> bool { 119 return std::invoke(__comp, 120 std::invoke(__proj, std::forward<decltype(__a)>(__a)), 121 std::invoke(__proj, std::forward<decltype(__b)>(__b))); 122 }; 123 124 // During initialization, members are allowed to refer to already initialized members 125 // (see http://eel.is/c++draft/dcl.init.aggr#6) 126 ranges::minmax_result<_ValueT> __result = {*__first, __result.min}; 127 if (__first == __last || ++__first == __last) 128 return __result; 129 130 if (__less(*__first, __result.min)) 131 __result.min = *__first; 132 else 133 __result.max = *__first; 134 135 while (++__first != __last) { 136 _ValueT __i = *__first; 137 if (++__first == __last) { 138 if (__less(__i, __result.min)) 139 __result.min = __i; 140 else if (!__less(__i, __result.max)) 141 __result.max = __i; 142 return __result; 143 } 144 145 if (__less(*__first, __i)) { 146 if (__less(*__first, __result.min)) 147 __result.min = *__first; 148 if (!__less(__i, __result.max)) 149 __result.max = std::move(__i); 150 } else { 151 if (__less(__i, __result.min)) 152 __result.min = std::move(__i); 153 if (!__less(*__first, __result.max)) 154 __result.max = *__first; 155 } 156 } 157 return __result; 158 } 159 } 160 }; 161 162 inline namespace __cpo { 163 inline constexpr auto minmax = __minmax{}; 164 } // namespace __cpo 165 } // namespace ranges 166 167 _LIBCPP_END_NAMESPACE_STD 168 169 _LIBCPP_POP_MACROS 170 171 #endif // _LIBCPP_STD_VER >= 20 172 173 #endif // _LIBCPP___ALGORITHM_RANGES_MINMAX_H 174