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_NEXT_PERMUTATION_H 10 #define _LIBCPP___ALGORITHM_NEXT_PERMUTATION_H 11 12 #include <__algorithm/comp.h> 13 #include <__algorithm/comp_ref_type.h> 14 #include <__algorithm/iterator_operations.h> 15 #include <__algorithm/reverse.h> 16 #include <__config> 17 #include <__iterator/iterator_traits.h> 18 #include <__utility/move.h> 19 #include <__utility/pair.h> 20 21 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 22 # pragma GCC system_header 23 #endif 24 25 _LIBCPP_PUSH_MACROS 26 #include <__undef_macros> 27 28 _LIBCPP_BEGIN_NAMESPACE_STD 29 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>; 34 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); 39 40 while (true) { 41 _BidirectionalIterator __ip1 = __i; 42 if (__comp(*--__i, *__ip1)) { 43 _BidirectionalIterator __j = __last_iter; 44 while (!__comp(*__i, *--__j)) 45 ; 46 _IterOps<_AlgPolicy>::iter_swap(__i, __j); 47 std::__reverse<_AlgPolicy>(__ip1, __last_iter); 48 return _Result(std::move(__last_iter), true); 49 } 50 if (__i == __first) { 51 std::__reverse<_AlgPolicy>(__first, __last_iter); 52 return _Result(std::move(__last_iter), false); 53 } 54 } 55 } 56 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)) 62 .second; 63 } 64 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<>()); 69 } 70 71 _LIBCPP_END_NAMESPACE_STD 72 73 _LIBCPP_POP_MACROS 74 75 #endif // _LIBCPP___ALGORITHM_NEXT_PERMUTATION_H 76