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 <__type_traits/invoke.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
26template <class _Comp, class _Proj>
27class _MinmaxElementLessFunc {
28 _Comp& __comp_;
29 _Proj& __proj_;
30
31public:
32 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR _MinmaxElementLessFunc(_Comp& __comp, _Proj& __proj)
33 : __comp_(__comp), __proj_(__proj) {}
34
35 template <class _Iter>
36 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 bool operator()(_Iter& __it1, _Iter& __it2) {
37 return std::__invoke(__comp_, std::__invoke(__proj_, *__it1), std::__invoke(__proj_, *__it2));
38 }
39};
40
41template <class _Iter, class _Sent, class _Proj, class _Comp>
42_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 pair<_Iter, _Iter>
43__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
81template <class _ForwardIterator, class _Compare>
82[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 pair<_ForwardIterator, _ForwardIterator>
83minmax_element(_ForwardIterator __first, _ForwardIterator __last, _Compare __comp) {
84 static_assert(
85 __has_forward_iterator_category<_ForwardIterator>::value, "std::minmax_element requires a ForwardIterator");
86 static_assert(
87 __is_callable<_Compare&, decltype(*__first), decltype(*__first)>::value, "The comparator has to be callable");
88 auto __proj = __identity();
89 return std::__minmax_element_impl(__first, __last, __comp, __proj);
90}
91
92template <class _ForwardIterator>
93[[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 pair<_ForwardIterator, _ForwardIterator>
94minmax_element(_ForwardIterator __first, _ForwardIterator __last) {
95 return std::minmax_element(__first, __last, __less<>());
96}
97
98_LIBCPP_END_NAMESPACE_STD
99
100#endif // _LIBCPP___ALGORITHM_MINMAX_ELEMENT_H
101