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_MINMAX_ELEMENT_H 10 #define _LIBCPP___ALGORITHM_MINMAX_ELEMENT_H 11 12 #include <__algorithm/comp.h> 13 #include <__config> 14 #include <__functional/identity.h> 15 #include <__iterator/iterator_traits.h> 16 #include <__utility/pair.h> 17 #include <type_traits> 18 19 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 20 # pragma GCC system_header 21 #endif 22 23 _LIBCPP_BEGIN_NAMESPACE_STD 24 25 template <class _Comp, class _Proj> 26 class _MinmaxElementLessFunc { 27 _Comp& __comp_; 28 _Proj& __proj_; 29 30 public: 31 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR 32 _MinmaxElementLessFunc(_Comp& __comp, _Proj& __proj) : __comp_(__comp), __proj_(__proj) {} 33 34 template <class _Iter> 35 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX11 36 bool operator()(_Iter& __it1, _Iter& __it2) { 37 return std::__invoke(__comp_, std::__invoke(__proj_, *__it1), std::__invoke(__proj_, *__it2)); 38 } 39 }; 40 41 template <class _Iter, class _Sent, class _Proj, class _Comp> 42 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX11 43 pair<_Iter, _Iter> __minmax_element_impl(_Iter __first, _Sent __last, _Comp& __comp, _Proj& __proj) { 44 auto __less = _MinmaxElementLessFunc<_Comp, _Proj>(__comp, __proj); 45 46 pair<_Iter, _Iter> __result(__first, __first); 47 if (__first == __last || ++__first == __last) 48 return __result; 49 50 if (__less(__first, __result.first)) 51 __result.first = __first; 52 else 53 __result.second = __first; 54 55 while (++__first != __last) { 56 _Iter __i = __first; 57 if (++__first == __last) { 58 if (__less(__i, __result.first)) 59 __result.first = __i; 60 else if (!__less(__i, __result.second)) 61 __result.second = __i; 62 return __result; 63 } 64 65 if (__less(__first, __i)) { 66 if (__less(__first, __result.first)) 67 __result.first = __first; 68 if (!__less(__i, __result.second)) 69 __result.second = __i; 70 } else { 71 if (__less(__i, __result.first)) 72 __result.first = __i; 73 if (!__less(__first, __result.second)) 74 __result.second = __first; 75 } 76 } 77 78 return __result; 79 } 80 81 template <class _ForwardIterator, class _Compare> 82 _LIBCPP_NODISCARD_EXT _LIBCPP_CONSTEXPR_AFTER_CXX11 83 pair<_ForwardIterator, _ForwardIterator> 84 minmax_element(_ForwardIterator __first, _ForwardIterator __last, _Compare __comp) { 85 static_assert(__is_cpp17_forward_iterator<_ForwardIterator>::value, 86 "std::minmax_element requires a ForwardIterator"); 87 static_assert(__is_callable<_Compare, decltype(*__first), decltype(*__first)>::value, 88 "The comparator has to be callable"); 89 auto __proj = __identity(); 90 return std::__minmax_element_impl(__first, __last, __comp, __proj); 91 } 92 93 template <class _ForwardIterator> 94 _LIBCPP_NODISCARD_EXT inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX11 95 pair<_ForwardIterator, _ForwardIterator> minmax_element(_ForwardIterator __first, _ForwardIterator __last) { 96 return std::minmax_element(__first, __last, __less<typename iterator_traits<_ForwardIterator>::value_type>()); 97 } 98 99 _LIBCPP_END_NAMESPACE_STD 100 101 #endif // _LIBCPP___ALGORITHM_MINMAX_ELEMENT_H 102