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_MAX_H
10 #define _LIBCPP___ALGORITHM_RANGES_MAX_H
11 
12 #include <__algorithm/ranges_min_element.h>
13 #include <__assert>
14 #include <__concepts/copyable.h>
15 #include <__config>
16 #include <__functional/identity.h>
17 #include <__functional/invoke.h>
18 #include <__functional/ranges_operations.h>
19 #include <__iterator/concepts.h>
20 #include <__iterator/projected.h>
21 #include <__ranges/access.h>
22 #include <__ranges/concepts.h>
23 #include <__type_traits/is_trivially_copyable.h>
24 #include <__utility/move.h>
25 #include <initializer_list>
26 
27 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
28 #  pragma GCC system_header
29 #endif
30 
31 #if _LIBCPP_STD_VER >= 20
32 
33 _LIBCPP_PUSH_MACROS
34 #  include <__undef_macros>
35 
36 _LIBCPP_BEGIN_NAMESPACE_STD
37 
38 namespace ranges {
39 namespace __max {
40 struct __fn {
41   template <class _Tp,
42             class _Proj                                                    = identity,
43             indirect_strict_weak_order<projected<const _Tp*, _Proj>> _Comp = ranges::less>
44   _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI constexpr const _Tp&
45   operator()(_LIBCPP_LIFETIMEBOUND const _Tp& __a,
46              _LIBCPP_LIFETIMEBOUND const _Tp& __b,
47              _Comp __comp = {},
48              _Proj __proj = {}) const {
49     return std::invoke(__comp, std::invoke(__proj, __a), std::invoke(__proj, __b)) ? __b : __a;
50   }
51 
52   template <copyable _Tp,
53             class _Proj                                                    = identity,
54             indirect_strict_weak_order<projected<const _Tp*, _Proj>> _Comp = ranges::less>
55   _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI constexpr _Tp
56   operator()(initializer_list<_Tp> __il, _Comp __comp = {}, _Proj __proj = {}) const {
57     _LIBCPP_ASSERT_UNCATEGORIZED(__il.begin() != __il.end(), "initializer_list must contain at least one element");
58 
59     auto __comp_lhs_rhs_swapped = [&](auto&& __lhs, auto&& __rhs) { return std::invoke(__comp, __rhs, __lhs); };
60     return *ranges::__min_element_impl(__il.begin(), __il.end(), __comp_lhs_rhs_swapped, __proj);
61   }
62 
63   template <input_range _Rp,
64             class _Proj                                                         = identity,
65             indirect_strict_weak_order<projected<iterator_t<_Rp>, _Proj>> _Comp = ranges::less>
66     requires indirectly_copyable_storable<iterator_t<_Rp>, range_value_t<_Rp>*>
67   _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI constexpr range_value_t<_Rp>
68   operator()(_Rp&& __r, _Comp __comp = {}, _Proj __proj = {}) const {
69     auto __first = ranges::begin(__r);
70     auto __last  = ranges::end(__r);
71 
72     _LIBCPP_ASSERT_UNCATEGORIZED(__first != __last, "range must contain at least one element");
73 
74     if constexpr (forward_range<_Rp> && !__is_cheap_to_copy<range_value_t<_Rp>>) {
75       auto __comp_lhs_rhs_swapped = [&](auto&& __lhs, auto&& __rhs) { return std::invoke(__comp, __rhs, __lhs); };
76       return *ranges::__min_element_impl(std::move(__first), std::move(__last), __comp_lhs_rhs_swapped, __proj);
77     } else {
78       range_value_t<_Rp> __result = *__first;
79       while (++__first != __last) {
80         if (std::invoke(__comp, std::invoke(__proj, __result), std::invoke(__proj, *__first)))
81           __result = *__first;
82       }
83       return __result;
84     }
85   }
86 };
87 } // namespace __max
88 
89 inline namespace __cpo {
90 inline constexpr auto max = __max::__fn{};
91 } // namespace __cpo
92 } // namespace ranges
93 
94 _LIBCPP_END_NAMESPACE_STD
95 
96 _LIBCPP_POP_MACROS
97 
98 #endif // _LIBCPP_STD_VER >= 20 &&
99 
100 #endif // _LIBCPP___ALGORITHM_RANGES_MAX_H
101