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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-exception6//7//===----------------------------------------------------------------------===//8 9#ifndef _LIBCPP___ALGORITHM_LEXICOGRAPHICAL_COMPARE_H10#define _LIBCPP___ALGORITHM_LEXICOGRAPHICAL_COMPARE_H11 12#include <__algorithm/comp.h>13#include <__algorithm/min.h>14#include <__algorithm/mismatch.h>15#include <__algorithm/simd_utils.h>16#include <__algorithm/unwrap_iter.h>17#include <__config>18#include <__functional/identity.h>19#include <__iterator/iterator_traits.h>20#include <__string/constexpr_c_functions.h>21#include <__type_traits/desugars_to.h>22#include <__type_traits/enable_if.h>23#include <__type_traits/invoke.h>24#include <__type_traits/is_equality_comparable.h>25#include <__type_traits/is_integral.h>26#include <__type_traits/is_trivially_lexicographically_comparable.h>27#include <__type_traits/is_volatile.h>28 29#if _LIBCPP_HAS_WIDE_CHARACTERS30# include <cwchar>31#endif32 33#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)34# pragma GCC system_header35#endif36 37_LIBCPP_PUSH_MACROS38#include <__undef_macros>39 40_LIBCPP_BEGIN_NAMESPACE_STD41 42template <class _Iter1, class _Sent1, class _Iter2, class _Sent2, class _Proj1, class _Proj2, class _Comp>43_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool __lexicographical_compare(44 _Iter1 __first1, _Sent1 __last1, _Iter2 __first2, _Sent2 __last2, _Comp& __comp, _Proj1& __proj1, _Proj2& __proj2) {45 while (__first2 != __last2) {46 if (__first1 == __last1 ||47 std::__invoke(__comp, std::__invoke(__proj1, *__first1), std::__invoke(__proj2, *__first2)))48 return true;49 if (std::__invoke(__comp, std::__invoke(__proj2, *__first2), std::__invoke(__proj1, *__first1)))50 return false;51 ++__first1;52 ++__first2;53 }54 return false;55}56 57#if _LIBCPP_STD_VER >= 1458 59// If the comparison operation is equivalent to < and that is a total order, we know that we can use equality comparison60// on that type instead to extract some information. Furthermore, if equality comparison on that type is trivial, the61// user can't observe that we're calling it. So instead of using the user-provided total order, we use std::mismatch,62// which uses equality comparison (and is vertorized). Additionally, if the type is trivially lexicographically63// comparable, we can go one step further and use std::memcmp directly instead of calling std::mismatch.64template <class _Tp,65 class _Proj1,66 class _Proj2,67 class _Comp,68 __enable_if_t<__desugars_to_v<__totally_ordered_less_tag, _Comp, _Tp, _Tp> && !is_volatile<_Tp>::value &&69 __libcpp_is_trivially_equality_comparable<_Tp, _Tp>::value &&70 __is_identity<_Proj1>::value && __is_identity<_Proj2>::value,71 int> = 0>72_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool73__lexicographical_compare(_Tp* __first1, _Tp* __last1, _Tp* __first2, _Tp* __last2, _Comp&, _Proj1&, _Proj2&) {74 if constexpr (__is_trivially_lexicographically_comparable_v<_Tp, _Tp>) {75 auto __res =76 std::__constexpr_memcmp(__first1, __first2, __element_count(std::min(__last1 - __first1, __last2 - __first2)));77 if (__res == 0)78 return __last1 - __first1 < __last2 - __first2;79 return __res < 0;80 }81# if _LIBCPP_HAS_WIDE_CHARACTERS82 else if constexpr (is_same<__remove_cv_t<_Tp>, wchar_t>::value) {83 auto __res = std::__constexpr_wmemcmp(__first1, __first2, std::min(__last1 - __first1, __last2 - __first2));84 if (__res == 0)85 return __last1 - __first1 < __last2 - __first2;86 return __res < 0;87 }88# endif // _LIBCPP_HAS_WIDE_CHARACTERS89 else {90 auto __res = std::mismatch(__first1, __last1, __first2, __last2);91 if (__res.second == __last2)92 return false;93 if (__res.first == __last1)94 return true;95 return *__res.first < *__res.second;96 }97}98 99#endif // _LIBCPP_STD_VER >= 14100 101template <class _InputIterator1, class _InputIterator2, class _Compare>102[[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool lexicographical_compare(103 _InputIterator1 __first1,104 _InputIterator1 __last1,105 _InputIterator2 __first2,106 _InputIterator2 __last2,107 _Compare __comp) {108 __identity __proj;109 return std::__lexicographical_compare(110 std::__unwrap_iter(__first1),111 std::__unwrap_iter(__last1),112 std::__unwrap_iter(__first2),113 std::__unwrap_iter(__last2),114 __comp,115 __proj,116 __proj);117}118 119template <class _InputIterator1, class _InputIterator2>120[[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool lexicographical_compare(121 _InputIterator1 __first1, _InputIterator1 __last1, _InputIterator2 __first2, _InputIterator2 __last2) {122 return std::lexicographical_compare(__first1, __last1, __first2, __last2, __less<>());123}124 125_LIBCPP_END_NAMESPACE_STD126 127_LIBCPP_POP_MACROS128 129#endif // _LIBCPP___ALGORITHM_LEXICOGRAPHICAL_COMPARE_H130