xref: /freebsd/contrib/llvm-project/libcxx/include/__algorithm/ranges_max.h (revision e32fecd0c2c3ee37c47ee100f169e7eb0282a873)
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 <__utility/move.h>
24 #include <initializer_list>
25 
26 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
27 #  pragma GCC system_header
28 #endif
29 
30 #if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES)
31 
32 _LIBCPP_PUSH_MACROS
33 #include <__undef_macros>
34 
35 _LIBCPP_BEGIN_NAMESPACE_STD
36 
37 namespace ranges {
38 namespace __max {
39 struct __fn {
40   template <class _Tp, class _Proj = identity,
41             indirect_strict_weak_order<projected<const _Tp*, _Proj>> _Comp = ranges::less>
42   _LIBCPP_HIDE_FROM_ABI constexpr
43   const _Tp& operator()(const _Tp& __a, const _Tp& __b, _Comp __comp = {}, _Proj __proj = {}) const {
44     return std::invoke(__comp, std::invoke(__proj, __a), std::invoke(__proj, __b)) ? __b : __a;
45   }
46 
47   template <copyable _Tp, class _Proj = identity,
48             indirect_strict_weak_order<projected<const _Tp*, _Proj>> _Comp = ranges::less>
49   _LIBCPP_HIDE_FROM_ABI constexpr
50   _Tp operator()(initializer_list<_Tp> __il, _Comp __comp = {}, _Proj __proj = {}) const {
51     _LIBCPP_ASSERT(__il.begin() != __il.end(), "initializer_list must contain at least one element");
52 
53     auto __comp_lhs_rhs_swapped = [&](auto&& __lhs, auto&& __rhs) { return std::invoke(__comp, __rhs, __lhs); };
54     return *ranges::__min_element_impl(__il.begin(), __il.end(), __comp_lhs_rhs_swapped, __proj);
55   }
56 
57   template <input_range _Rp, class _Proj = identity,
58             indirect_strict_weak_order<projected<iterator_t<_Rp>, _Proj>> _Comp = ranges::less>
59     requires indirectly_copyable_storable<iterator_t<_Rp>, range_value_t<_Rp>*>
60   _LIBCPP_HIDE_FROM_ABI constexpr
61   range_value_t<_Rp> operator()(_Rp&& __r, _Comp __comp = {}, _Proj __proj = {}) const {
62     auto __first = ranges::begin(__r);
63     auto __last = ranges::end(__r);
64 
65     _LIBCPP_ASSERT(__first != __last, "range must contain at least one element");
66 
67     if constexpr (forward_range<_Rp>) {
68       auto __comp_lhs_rhs_swapped = [&](auto&& __lhs, auto&& __rhs) { return std::invoke(__comp, __rhs, __lhs); };
69       return *ranges::__min_element_impl(std::move(__first), std::move(__last), __comp_lhs_rhs_swapped, __proj);
70     } else {
71       range_value_t<_Rp> __result = *__first;
72       while (++__first != __last) {
73         if (std::invoke(__comp, std::invoke(__proj, __result), std::invoke(__proj, *__first)))
74           __result = *__first;
75       }
76       return __result;
77     }
78   }
79 };
80 } // namespace __max
81 
82 inline namespace __cpo {
83   inline constexpr auto max = __max::__fn{};
84 } // namespace __cpo
85 } // namespace ranges
86 
87 _LIBCPP_END_NAMESPACE_STD
88 
89 _LIBCPP_POP_MACROS
90 
91 #endif // _LIBCPP_STD_VER > 17 && && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES)
92 
93 #endif // _LIBCPP___ALGORITHM_RANGES_MAX_H
94