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 <__utility/forward.h> 27 #include <__utility/move.h> 28 #include <__utility/pair.h> 29 #include <initializer_list> 30 31 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 32 # pragma GCC system_header 33 #endif 34 35 #if _LIBCPP_STD_VER > 17 36 37 _LIBCPP_PUSH_MACROS 38 #include <__undef_macros> 39 40 _LIBCPP_BEGIN_NAMESPACE_STD 41 42 namespace ranges { 43 template <class _T1> 44 using minmax_result = min_max_result<_T1>; 45 46 namespace __minmax { 47 struct __fn { 48 template <class _Type, class _Proj = identity, 49 indirect_strict_weak_order<projected<const _Type*, _Proj>> _Comp = ranges::less> 50 _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI constexpr ranges::minmax_result<const _Type&> 51 operator()(_LIBCPP_LIFETIMEBOUND const _Type& __a, 52 _LIBCPP_LIFETIMEBOUND const _Type& __b, 53 _Comp __comp = {}, 54 _Proj __proj = {}) const { 55 if (std::invoke(__comp, std::invoke(__proj, __b), std::invoke(__proj, __a))) 56 return {__b, __a}; 57 return {__a, __b}; 58 } 59 60 template <copyable _Type, class _Proj = identity, 61 indirect_strict_weak_order<projected<const _Type*, _Proj>> _Comp = ranges::less> 62 _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI constexpr 63 ranges::minmax_result<_Type> operator()(initializer_list<_Type> __il, _Comp __comp = {}, _Proj __proj = {}) const { 64 _LIBCPP_ASSERT(__il.begin() != __il.end(), "initializer_list has to contain at least one element"); 65 auto __iters = std::__minmax_element_impl(__il.begin(), __il.end(), __comp, __proj); 66 return ranges::minmax_result<_Type> { *__iters.first, *__iters.second }; 67 } 68 69 template <input_range _Range, class _Proj = identity, 70 indirect_strict_weak_order<projected<iterator_t<_Range>, _Proj>> _Comp = ranges::less> 71 requires indirectly_copyable_storable<iterator_t<_Range>, range_value_t<_Range>*> 72 _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI constexpr 73 ranges::minmax_result<range_value_t<_Range>> operator()(_Range&& __r, _Comp __comp = {}, _Proj __proj = {}) const { 74 auto __first = ranges::begin(__r); 75 auto __last = ranges::end(__r); 76 using _ValueT = range_value_t<_Range>; 77 78 _LIBCPP_ASSERT(__first != __last, "range has to contain at least one element"); 79 80 if constexpr (forward_range<_Range>) { 81 // Special-case the one element case. Avoid repeatedly initializing objects from the result of an iterator 82 // dereference when doing so might not be idempotent. The `if constexpr` avoids the extra branch in cases where 83 // it's not needed. 84 if constexpr (!same_as<remove_cvref_t<range_reference_t<_Range>>, _ValueT> || 85 is_rvalue_reference_v<range_reference_t<_Range>>) { 86 if (ranges::next(__first) == __last) { 87 // During initialization, members are allowed to refer to already initialized members 88 // (see http://eel.is/c++draft/dcl.init.aggr#6) 89 minmax_result<_ValueT> __result = {*__first, __result.min}; 90 return __result; 91 } 92 } 93 auto __result = std::__minmax_element_impl(__first, __last, __comp, __proj); 94 return {*__result.first, *__result.second}; 95 } else { 96 // input_iterators can't be copied, so the implementation for input_iterators has to store 97 // the values instead of a pointer to the correct values 98 auto __less = [&](auto&& __a, auto&& __b) -> bool { 99 return std::invoke(__comp, std::invoke(__proj, std::forward<decltype(__a)>(__a)), 100 std::invoke(__proj, std::forward<decltype(__b)>(__b))); 101 }; 102 103 // During initialization, members are allowed to refer to already initialized members 104 // (see http://eel.is/c++draft/dcl.init.aggr#6) 105 ranges::minmax_result<_ValueT> __result = {*__first, __result.min}; 106 if (__first == __last || ++__first == __last) 107 return __result; 108 109 if (__less(*__first, __result.min)) 110 __result.min = *__first; 111 else 112 __result.max = *__first; 113 114 while (++__first != __last) { 115 _ValueT __i = *__first; 116 if (++__first == __last) { 117 if (__less(__i, __result.min)) 118 __result.min = __i; 119 else if (!__less(__i, __result.max)) 120 __result.max = __i; 121 return __result; 122 } 123 124 if (__less(*__first, __i)) { 125 if (__less(*__first, __result.min)) 126 __result.min = *__first; 127 if (!__less(__i, __result.max)) 128 __result.max = std::move(__i); 129 } else { 130 if (__less(__i, __result.min)) 131 __result.min = std::move(__i); 132 if (!__less(*__first, __result.max)) 133 __result.max = *__first; 134 } 135 } 136 return __result; 137 } 138 } 139 }; 140 } // namespace __minmax 141 142 inline namespace __cpo { 143 inline constexpr auto minmax = __minmax::__fn{}; 144 } // namespace __cpo 145 } // namespace ranges 146 147 _LIBCPP_END_NAMESPACE_STD 148 149 _LIBCPP_POP_MACROS 150 151 #endif // _LIBCPP_STD_VER > 17 152 153 #endif // _LIBCPP___ALGORITHM_RANGES_MINMAX_H 154