1 //===----------------------------------------------------------------------===//
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
7 //===----------------------------------------------------------------------===//
9 #ifndef _LIBCPP___ALGORITHM_RANGES_MINMAX_H
10 #define _LIBCPP___ALGORITHM_RANGES_MINMAX_H
12 #include <__cxx03/__algorithm/min_max_result.h>
13 #include <__cxx03/__algorithm/minmax_element.h>
14 #include <__cxx03/__assert>
15 #include <__cxx03/__concepts/copyable.h>
16 #include <__cxx03/__concepts/same_as.h>
17 #include <__cxx03/__config>
18 #include <__cxx03/__functional/identity.h>
19 #include <__cxx03/__functional/invoke.h>
20 #include <__cxx03/__functional/ranges_operations.h>
21 #include <__cxx03/__iterator/concepts.h>
22 #include <__cxx03/__iterator/next.h>
23 #include <__cxx03/__iterator/projected.h>
24 #include <__cxx03/__ranges/access.h>
25 #include <__cxx03/__ranges/concepts.h>
26 #include <__cxx03/__type_traits/desugars_to.h>
27 #include <__cxx03/__type_traits/is_reference.h>
28 #include <__cxx03/__type_traits/is_trivially_copyable.h>
29 #include <__cxx03/__type_traits/remove_cvref.h>
30 #include <__cxx03/__utility/forward.h>
31 #include <__cxx03/__utility/move.h>
32 #include <__cxx03/__utility/pair.h>
33 #include <__cxx03/initializer_list>
35 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
36 # pragma GCC system_header
39 #if _LIBCPP_STD_VER >= 20
42 # include <__cxx03/__undef_macros>
44 _LIBCPP_BEGIN_NAMESPACE_STD
48 using minmax_result
= min_max_result
<_T1
>;
52 template <class _Type
,
53 class _Proj
= identity
,
54 indirect_strict_weak_order
<projected
<const _Type
*, _Proj
>> _Comp
= ranges::less
>
55 [[nodiscard
]] _LIBCPP_HIDE_FROM_ABI
constexpr ranges::minmax_result
<const _Type
&>
56 operator()(_LIBCPP_LIFETIMEBOUND
const _Type
& __a
,
57 _LIBCPP_LIFETIMEBOUND
const _Type
& __b
,
59 _Proj __proj
= {}) const {
60 if (std::invoke(__comp
, std::invoke(__proj
, __b
), std::invoke(__proj
, __a
)))
65 template <copyable _Type
,
66 class _Proj
= identity
,
67 indirect_strict_weak_order
<projected
<const _Type
*, _Proj
>> _Comp
= ranges::less
>
68 [[nodiscard
]] _LIBCPP_HIDE_FROM_ABI
constexpr ranges::minmax_result
<_Type
>
69 operator()(initializer_list
<_Type
> __il
, _Comp __comp
= {}, _Proj __proj
= {}) const {
70 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(
71 __il
.begin() != __il
.end(), "initializer_list has to contain at least one element");
72 auto __iters
= std::__minmax_element_impl(__il
.begin(), __il
.end(), __comp
, __proj
);
73 return ranges::minmax_result
<_Type
>{*__iters
.first
, *__iters
.second
};
76 template <input_range _Range
,
77 class _Proj
= identity
,
78 indirect_strict_weak_order
<projected
<iterator_t
<_Range
>, _Proj
>> _Comp
= ranges::less
>
79 requires indirectly_copyable_storable
<iterator_t
<_Range
>, range_value_t
<_Range
>*>
80 [[nodiscard
]] _LIBCPP_HIDE_FROM_ABI
constexpr ranges::minmax_result
<range_value_t
<_Range
>>
81 operator()(_Range
&& __r
, _Comp __comp
= {}, _Proj __proj
= {}) const {
82 auto __first
= ranges::begin(__r
);
83 auto __last
= ranges::end(__r
);
84 using _ValueT
= range_value_t
<_Range
>;
86 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__first
!= __last
, "range has to contain at least one element");
88 // This optimiation is not in minmax_element because clang doesn't see through the pointers and as a result doesn't
89 // vectorize the code.
90 if constexpr (contiguous_range
<_Range
> && is_integral_v
<_ValueT
> &&
91 __is_cheap_to_copy
<_ValueT
> & __is_identity
<_Proj
>::value
&&
92 __desugars_to_v
<__less_tag
, _Comp
, _ValueT
, _ValueT
>) {
93 minmax_result
<_ValueT
> __result
= {__r
[0], __r
[0]};
94 for (auto __e
: __r
) {
95 if (__e
< __result
.min
)
97 if (__result
.max
< __e
)
101 } else if constexpr (forward_range
<_Range
>) {
102 // Special-case the one element case. Avoid repeatedly initializing objects from the result of an iterator
103 // dereference when doing so might not be idempotent. The `if constexpr` avoids the extra branch in cases where
105 if constexpr (!same_as
<remove_cvref_t
<range_reference_t
<_Range
>>, _ValueT
> ||
106 is_rvalue_reference_v
<range_reference_t
<_Range
>>) {
107 if (ranges::next(__first
) == __last
) {
108 // During initialization, members are allowed to refer to already initialized members
109 // (see http://eel.is/c++draft/dcl.init.aggr#6)
110 minmax_result
<_ValueT
> __result
= {*__first
, __result
.min
};
114 auto __result
= std::__minmax_element_impl(__first
, __last
, __comp
, __proj
);
115 return {*__result
.first
, *__result
.second
};
117 // input_iterators can't be copied, so the implementation for input_iterators has to store
118 // the values instead of a pointer to the correct values
119 auto __less
= [&](auto&& __a
, auto&& __b
) -> bool {
120 return std::invoke(__comp
,
121 std::invoke(__proj
, std::forward
<decltype(__a
)>(__a
)),
122 std::invoke(__proj
, std::forward
<decltype(__b
)>(__b
)));
125 // During initialization, members are allowed to refer to already initialized members
126 // (see http://eel.is/c++draft/dcl.init.aggr#6)
127 ranges::minmax_result
<_ValueT
> __result
= {*__first
, __result
.min
};
128 if (__first
== __last
|| ++__first
== __last
)
131 if (__less(*__first
, __result
.min
))
132 __result
.min
= *__first
;
134 __result
.max
= *__first
;
136 while (++__first
!= __last
) {
137 _ValueT __i
= *__first
;
138 if (++__first
== __last
) {
139 if (__less(__i
, __result
.min
))
141 else if (!__less(__i
, __result
.max
))
146 if (__less(*__first
, __i
)) {
147 if (__less(*__first
, __result
.min
))
148 __result
.min
= *__first
;
149 if (!__less(__i
, __result
.max
))
150 __result
.max
= std::move(__i
);
152 if (__less(__i
, __result
.min
))
153 __result
.min
= std::move(__i
);
154 if (!__less(*__first
, __result
.max
))
155 __result
.max
= *__first
;
162 } // namespace __minmax
164 inline namespace __cpo
{
165 inline constexpr auto minmax
= __minmax::__fn
{};
167 } // namespace ranges
169 _LIBCPP_END_NAMESPACE_STD
173 #endif // _LIBCPP_STD_VER >= 20
175 #endif // _LIBCPP___ALGORITHM_RANGES_MINMAX_H