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 <__config> 13 #include <__algorithm/comp.h> 14 #include <__algorithm/comp_ref_type.h> 15 #include <__algorithm/reverse.h> 16 #include <__iterator/iterator_traits.h> 17 #include <__utility/swap.h> 18 19 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 20 #pragma GCC system_header 21 #endif 22 23 _LIBCPP_PUSH_MACROS 24 #include <__undef_macros> 25 26 _LIBCPP_BEGIN_NAMESPACE_STD 27 28 template <class _Compare, class _BidirectionalIterator> 29 _LIBCPP_CONSTEXPR_AFTER_CXX17 bool 30 __next_permutation(_BidirectionalIterator __first, _BidirectionalIterator __last, _Compare __comp) 31 { 32 _BidirectionalIterator __i = __last; 33 if (__first == __last || __first == --__i) 34 return false; 35 while (true) 36 { 37 _BidirectionalIterator __ip1 = __i; 38 if (__comp(*--__i, *__ip1)) 39 { 40 _BidirectionalIterator __j = __last; 41 while (!__comp(*__i, *--__j)) 42 ; 43 swap(*__i, *__j); 44 _VSTD::reverse(__ip1, __last); 45 return true; 46 } 47 if (__i == __first) 48 { 49 _VSTD::reverse(__first, __last); 50 return false; 51 } 52 } 53 } 54 55 template <class _BidirectionalIterator, class _Compare> 56 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 57 bool 58 next_permutation(_BidirectionalIterator __first, _BidirectionalIterator __last, _Compare __comp) 59 { 60 typedef typename __comp_ref_type<_Compare>::type _Comp_ref; 61 return _VSTD::__next_permutation<_Comp_ref>(__first, __last, __comp); 62 } 63 64 template <class _BidirectionalIterator> 65 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 66 bool 67 next_permutation(_BidirectionalIterator __first, _BidirectionalIterator __last) 68 { 69 return _VSTD::next_permutation(__first, __last, 70 __less<typename iterator_traits<_BidirectionalIterator>::value_type>()); 71 } 72 73 _LIBCPP_END_NAMESPACE_STD 74 75 _LIBCPP_POP_MACROS 76 77 #endif // _LIBCPP___ALGORITHM_NEXT_PERMUTATION_H 78