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_NEXT_PERMUTATION_H
10 #define _LIBCPP___ALGORITHM_NEXT_PERMUTATION_H
12 #include <__cxx03/__algorithm/comp.h>
13 #include <__cxx03/__algorithm/comp_ref_type.h>
14 #include <__cxx03/__algorithm/iterator_operations.h>
15 #include <__cxx03/__algorithm/reverse.h>
16 #include <__cxx03/__config>
17 #include <__cxx03/__iterator/iterator_traits.h>
18 #include <__cxx03/__utility/move.h>
19 #include <__cxx03/__utility/pair.h>
21 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
22 # pragma GCC system_header
26 #include <__cxx03/__undef_macros>
28 _LIBCPP_BEGIN_NAMESPACE_STD
30 template <class _AlgPolicy
, class _Compare
, class _BidirectionalIterator
, class _Sentinel
>
31 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair
<_BidirectionalIterator
, bool>
32 __next_permutation(_BidirectionalIterator __first
, _Sentinel __last
, _Compare
&& __comp
) {
33 using _Result
= pair
<_BidirectionalIterator
, bool>;
35 _BidirectionalIterator __last_iter
= _IterOps
<_AlgPolicy
>::next(__first
, __last
);
36 _BidirectionalIterator __i
= __last_iter
;
37 if (__first
== __last
|| __first
== --__i
)
38 return _Result(std::move(__last_iter
), false);
41 _BidirectionalIterator __ip1
= __i
;
42 if (__comp(*--__i
, *__ip1
)) {
43 _BidirectionalIterator __j
= __last_iter
;
44 while (!__comp(*__i
, *--__j
))
46 _IterOps
<_AlgPolicy
>::iter_swap(__i
, __j
);
47 std::__reverse
<_AlgPolicy
>(__ip1
, __last_iter
);
48 return _Result(std::move(__last_iter
), true);
51 std::__reverse
<_AlgPolicy
>(__first
, __last_iter
);
52 return _Result(std::move(__last_iter
), false);
57 template <class _BidirectionalIterator
, class _Compare
>
58 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20
bool
59 next_permutation(_BidirectionalIterator __first
, _BidirectionalIterator __last
, _Compare __comp
) {
60 return std::__next_permutation
<_ClassicAlgPolicy
>(
61 std::move(__first
), std::move(__last
), static_cast<__comp_ref_type
<_Compare
> >(__comp
))
65 template <class _BidirectionalIterator
>
66 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20
bool
67 next_permutation(_BidirectionalIterator __first
, _BidirectionalIterator __last
) {
68 return std::next_permutation(__first
, __last
, __less
<>());
71 _LIBCPP_END_NAMESPACE_STD
75 #endif // _LIBCPP___ALGORITHM_NEXT_PERMUTATION_H