xref: /freebsd/contrib/llvm-project/libcxx/include/__algorithm/ranges_min.h (revision cccdaf507eee8fb34494b4624eb85bb951e323c8)
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_MIN_H
10 #define _LIBCPP___ALGORITHM_RANGES_MIN_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 <initializer_list>
24 
25 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
26 #  pragma GCC system_header
27 #endif
28 
29 #if _LIBCPP_STD_VER > 17
30 
31 _LIBCPP_PUSH_MACROS
32 #include <__undef_macros>
33 
34 _LIBCPP_BEGIN_NAMESPACE_STD
35 
36 namespace ranges {
37 namespace __min {
38 struct __fn {
39   template <class _Tp, class _Proj = identity,
40             indirect_strict_weak_order<projected<const _Tp*, _Proj>> _Comp = ranges::less>
41   _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI constexpr
42   const _Tp& operator()(const _Tp& __a, const _Tp& __b, _Comp __comp = {}, _Proj __proj = {}) const {
43     return std::invoke(__comp, std::invoke(__proj, __b), std::invoke(__proj, __a)) ? __b : __a;
44   }
45 
46   template <copyable _Tp, class _Proj = identity,
47             indirect_strict_weak_order<projected<const _Tp*, _Proj>> _Comp = ranges::less>
48   _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI constexpr
49   _Tp operator()(initializer_list<_Tp> __il, _Comp __comp = {}, _Proj __proj = {}) const {
50     _LIBCPP_ASSERT(__il.begin() != __il.end(), "initializer_list must contain at least one element");
51     return *ranges::__min_element_impl(__il.begin(), __il.end(), __comp, __proj);
52   }
53 
54   template <input_range _Rp, class _Proj = identity,
55             indirect_strict_weak_order<projected<iterator_t<_Rp>, _Proj>> _Comp = ranges::less>
56     requires indirectly_copyable_storable<iterator_t<_Rp>, range_value_t<_Rp>*>
57   _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI constexpr
58   range_value_t<_Rp> operator()(_Rp&& __r, _Comp __comp = {}, _Proj __proj = {}) const {
59     auto __first = ranges::begin(__r);
60     auto __last = ranges::end(__r);
61 
62     _LIBCPP_ASSERT(__first != __last, "range must contain at least one element");
63 
64     if constexpr (forward_range<_Rp>) {
65       return *ranges::__min_element_impl(__first, __last, __comp, __proj);
66     } else {
67       range_value_t<_Rp> __result = *__first;
68       while (++__first != __last) {
69         if (std::invoke(__comp, std::invoke(__proj, *__first), std::invoke(__proj, __result)))
70           __result = *__first;
71       }
72       return __result;
73     }
74   }
75 };
76 } // namespace __min
77 
78 inline namespace __cpo {
79   inline constexpr auto min = __min::__fn{};
80 } // namespace __cpo
81 } // namespace ranges
82 
83 _LIBCPP_END_NAMESPACE_STD
84 
85 _LIBCPP_POP_MACROS
86 
87 #endif // _LIBCPP_STD_VER > 17 &&
88 
89 #endif // _LIBCPP___ALGORITHM_RANGES_MIN_H
90