xref: /llvm-project/libcxx/include/__algorithm/ranges_min_element.h (revision 368faacac7525e538fa6680aea74e19a75e3458d)
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_ELEMENT_H
10 #define _LIBCPP___ALGORITHM_RANGES_MIN_ELEMENT_H
11 
12 #include <__config>
13 #include <__functional/identity.h>
14 #include <__functional/invoke.h>
15 #include <__functional/ranges_operations.h>
16 #include <__iterator/concepts.h>
17 #include <__iterator/projected.h>
18 #include <__ranges/access.h>
19 #include <__ranges/concepts.h>
20 #include <__ranges/dangling.h>
21 #include <__utility/forward.h>
22 
23 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
24 #  pragma GCC system_header
25 #endif
26 
27 #if !defined(_LIBCPP_HAS_NO_CONCEPTS) && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES)
28 
29 _LIBCPP_BEGIN_NAMESPACE_STD
30 
31 namespace ranges {
32 namespace __min_element {
33 struct __fn {
34   template <class _Ip, class _Sp, class _Proj, class _Comp>
35   _LIBCPP_HIDE_FROM_ABI static constexpr
36   _Ip __go(_Ip __first, _Sp __last, _Comp& __comp, _Proj& __proj) {
37     if (__first == __last)
38       return __first;
39 
40     _Ip __i = __first;
41     while (++__i != __last)
42       if (std::invoke(__comp, std::invoke(__proj, *__i), std::invoke(__proj, *__first)))
43         __first = __i;
44     return __first;
45   }
46 
47   template <forward_iterator _Ip, sentinel_for<_Ip> _Sp, class _Proj = identity,
48             indirect_strict_weak_order<projected<_Ip, _Proj>> _Comp = ranges::less>
49   _LIBCPP_HIDE_FROM_ABI constexpr
50   _Ip operator()(_Ip __first, _Sp __last, _Comp __comp = {}, _Proj __proj = {}) const {
51     return __go(__first, __last, __comp, __proj);
52   }
53 
54   template <forward_range _Rp, class _Proj = identity,
55             indirect_strict_weak_order<projected<iterator_t<_Rp>, _Proj>> _Comp = ranges::less>
56   _LIBCPP_HIDE_FROM_ABI constexpr
57   borrowed_iterator_t<_Rp> operator()(_Rp&& __r, _Comp __comp = {}, _Proj __proj = {}) const {
58     return __go(ranges::begin(__r), ranges::end(__r), __comp, __proj);
59   }
60 };
61 } // namespace __min_element
62 
63 inline namespace __cpo {
64   inline constexpr auto min_element = __min_element::__fn{};
65 } // namespace __cpo
66 } // namespace ranges
67 
68 _LIBCPP_END_NAMESPACE_STD
69 
70 #endif // !defined(_LIBCPP_HAS_NO_CONCEPTS) && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES)
71 
72 #endif // _LIBCPP___ALGORITHM_RANGES_MIN_ELEMENT_H
73