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 <__functional/invoke.h> 16 #include <__iterator/iterator_traits.h> 17 #include <__type_traits/is_callable.h> 18 #include <__utility/pair.h> 19 20 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 21 # pragma GCC system_header 22 #endif 23 24 _LIBCPP_BEGIN_NAMESPACE_STD 25 26 template <class _Comp, class _Proj> 27 class _MinmaxElementLessFunc { 28 _Comp& __comp_; 29 _Proj& __proj_; 30 31 public: 32 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR 33 _MinmaxElementLessFunc(_Comp& __comp, _Proj& __proj) : __comp_(__comp), __proj_(__proj) {} 34 35 template <class _Iter> 36 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 37 bool operator()(_Iter& __it1, _Iter& __it2) { 38 return std::__invoke(__comp_, std::__invoke(__proj_, *__it1), std::__invoke(__proj_, *__it2)); 39 } 40 }; 41 42 template <class _Iter, class _Sent, class _Proj, class _Comp> 43 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 44 pair<_Iter, _Iter> __minmax_element_impl(_Iter __first, _Sent __last, _Comp& __comp, _Proj& __proj) { 45 auto __less = _MinmaxElementLessFunc<_Comp, _Proj>(__comp, __proj); 46 47 pair<_Iter, _Iter> __result(__first, __first); 48 if (__first == __last || ++__first == __last) 49 return __result; 50 51 if (__less(__first, __result.first)) 52 __result.first = __first; 53 else 54 __result.second = __first; 55 56 while (++__first != __last) { 57 _Iter __i = __first; 58 if (++__first == __last) { 59 if (__less(__i, __result.first)) 60 __result.first = __i; 61 else if (!__less(__i, __result.second)) 62 __result.second = __i; 63 return __result; 64 } 65 66 if (__less(__first, __i)) { 67 if (__less(__first, __result.first)) 68 __result.first = __first; 69 if (!__less(__i, __result.second)) 70 __result.second = __i; 71 } else { 72 if (__less(__i, __result.first)) 73 __result.first = __i; 74 if (!__less(__first, __result.second)) 75 __result.second = __first; 76 } 77 } 78 79 return __result; 80 } 81 82 template <class _ForwardIterator, class _Compare> 83 _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 84 pair<_ForwardIterator, _ForwardIterator> 85 minmax_element(_ForwardIterator __first, _ForwardIterator __last, _Compare __comp) { 86 static_assert(__has_forward_iterator_category<_ForwardIterator>::value, 87 "std::minmax_element requires a ForwardIterator"); 88 static_assert(__is_callable<_Compare, decltype(*__first), decltype(*__first)>::value, 89 "The comparator has to be callable"); 90 auto __proj = __identity(); 91 return std::__minmax_element_impl(__first, __last, __comp, __proj); 92 } 93 94 template <class _ForwardIterator> 95 _LIBCPP_NODISCARD_EXT inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 96 pair<_ForwardIterator, _ForwardIterator> minmax_element(_ForwardIterator __first, _ForwardIterator __last) { 97 return std::minmax_element(__first, __last, __less<>()); 98 } 99 100 _LIBCPP_END_NAMESPACE_STD 101 102 #endif // _LIBCPP___ALGORITHM_MINMAX_ELEMENT_H 103