1 // -*- C++ -*- 2 //===----------------------------------------------------------------------===// 3 // 4 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 5 // See https://llvm.org/LICENSE.txt for license information. 6 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 7 // 8 //===----------------------------------------------------------------------===// 9 10 #ifndef _LIBCPP___ALGORITHM_FIND_H 11 #define _LIBCPP___ALGORITHM_FIND_H 12 13 #include <__algorithm/find_segment_if.h> 14 #include <__algorithm/min.h> 15 #include <__algorithm/unwrap_iter.h> 16 #include <__bit/countr.h> 17 #include <__bit/invert_if.h> 18 #include <__config> 19 #include <__functional/identity.h> 20 #include <__fwd/bit_reference.h> 21 #include <__iterator/segmented_iterator.h> 22 #include <__string/constexpr_c_functions.h> 23 #include <__type_traits/enable_if.h> 24 #include <__type_traits/invoke.h> 25 #include <__type_traits/is_equality_comparable.h> 26 #include <__type_traits/is_integral.h> 27 #include <__type_traits/is_signed.h> 28 #include <__utility/move.h> 29 #include <limits> 30 31 #if _LIBCPP_HAS_WIDE_CHARACTERS 32 # include <cwchar> 33 #endif 34 35 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 36 # pragma GCC system_header 37 #endif 38 39 _LIBCPP_PUSH_MACROS 40 #include <__undef_macros> 41 42 _LIBCPP_BEGIN_NAMESPACE_STD 43 44 // generic implementation 45 template <class _Iter, class _Sent, class _Tp, class _Proj> 46 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Iter 47 __find(_Iter __first, _Sent __last, const _Tp& __value, _Proj& __proj) { 48 for (; __first != __last; ++__first) 49 if (std::__invoke(__proj, *__first) == __value) 50 break; 51 return __first; 52 } 53 54 // trivially equality comparable implementations 55 template <class _Tp, 56 class _Up, 57 class _Proj, 58 __enable_if_t<__is_identity<_Proj>::value && __libcpp_is_trivially_equality_comparable<_Tp, _Up>::value && 59 sizeof(_Tp) == 1, 60 int> = 0> 61 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Tp* __find(_Tp* __first, _Tp* __last, const _Up& __value, _Proj&) { 62 if (auto __ret = std::__constexpr_memchr(__first, __value, __last - __first)) 63 return __ret; 64 return __last; 65 } 66 67 #if _LIBCPP_HAS_WIDE_CHARACTERS 68 template <class _Tp, 69 class _Up, 70 class _Proj, 71 __enable_if_t<__is_identity<_Proj>::value && __libcpp_is_trivially_equality_comparable<_Tp, _Up>::value && 72 sizeof(_Tp) == sizeof(wchar_t) && _LIBCPP_ALIGNOF(_Tp) >= _LIBCPP_ALIGNOF(wchar_t), 73 int> = 0> 74 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Tp* __find(_Tp* __first, _Tp* __last, const _Up& __value, _Proj&) { 75 if (auto __ret = std::__constexpr_wmemchr(__first, __value, __last - __first)) 76 return __ret; 77 return __last; 78 } 79 #endif // _LIBCPP_HAS_WIDE_CHARACTERS 80 81 // TODO: This should also be possible to get right with different signedness 82 // cast integral types to allow vectorization 83 template <class _Tp, 84 class _Up, 85 class _Proj, 86 __enable_if_t<__is_identity<_Proj>::value && !__libcpp_is_trivially_equality_comparable<_Tp, _Up>::value && 87 is_integral<_Tp>::value && is_integral<_Up>::value && 88 is_signed<_Tp>::value == is_signed<_Up>::value, 89 int> = 0> 90 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Tp* 91 __find(_Tp* __first, _Tp* __last, const _Up& __value, _Proj& __proj) { 92 if (__value < numeric_limits<_Tp>::min() || __value > numeric_limits<_Tp>::max()) 93 return __last; 94 return std::__find(__first, __last, _Tp(__value), __proj); 95 } 96 97 // __bit_iterator implementation 98 template <bool _ToFind, class _Cp, bool _IsConst> 99 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI __bit_iterator<_Cp, _IsConst> 100 __find_bool(__bit_iterator<_Cp, _IsConst> __first, typename _Cp::size_type __n) { 101 using _It = __bit_iterator<_Cp, _IsConst>; 102 using __storage_type = typename _It::__storage_type; 103 104 const int __bits_per_word = _It::__bits_per_word; 105 // do first partial word 106 if (__first.__ctz_ != 0) { 107 __storage_type __clz_f = static_cast<__storage_type>(__bits_per_word - __first.__ctz_); 108 __storage_type __dn = std::min(__clz_f, __n); 109 __storage_type __m = (~__storage_type(0) << __first.__ctz_) & (~__storage_type(0) >> (__clz_f - __dn)); 110 __storage_type __b = std::__invert_if<!_ToFind>(*__first.__seg_) & __m; 111 if (__b) 112 return _It(__first.__seg_, static_cast<unsigned>(std::__libcpp_ctz(__b))); 113 if (__n == __dn) 114 return __first + __n; 115 __n -= __dn; 116 ++__first.__seg_; 117 } 118 // do middle whole words 119 for (; __n >= __bits_per_word; ++__first.__seg_, __n -= __bits_per_word) { 120 __storage_type __b = std::__invert_if<!_ToFind>(*__first.__seg_); 121 if (__b) 122 return _It(__first.__seg_, static_cast<unsigned>(std::__libcpp_ctz(__b))); 123 } 124 // do last partial word 125 if (__n > 0) { 126 __storage_type __m = ~__storage_type(0) >> (__bits_per_word - __n); 127 __storage_type __b = std::__invert_if<!_ToFind>(*__first.__seg_) & __m; 128 if (__b) 129 return _It(__first.__seg_, static_cast<unsigned>(std::__libcpp_ctz(__b))); 130 } 131 return _It(__first.__seg_, static_cast<unsigned>(__n)); 132 } 133 134 template <class _Cp, bool _IsConst, class _Tp, class _Proj, __enable_if_t<__is_identity<_Proj>::value, int> = 0> 135 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 __bit_iterator<_Cp, _IsConst> 136 __find(__bit_iterator<_Cp, _IsConst> __first, __bit_iterator<_Cp, _IsConst> __last, const _Tp& __value, _Proj&) { 137 if (static_cast<bool>(__value)) 138 return std::__find_bool<true>(__first, static_cast<typename _Cp::size_type>(__last - __first)); 139 return std::__find_bool<false>(__first, static_cast<typename _Cp::size_type>(__last - __first)); 140 } 141 142 // segmented iterator implementation 143 144 template <class> 145 struct __find_segment; 146 147 template <class _SegmentedIterator, 148 class _Tp, 149 class _Proj, 150 __enable_if_t<__is_segmented_iterator<_SegmentedIterator>::value, int> = 0> 151 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _SegmentedIterator 152 __find(_SegmentedIterator __first, _SegmentedIterator __last, const _Tp& __value, _Proj& __proj) { 153 return std::__find_segment_if(std::move(__first), std::move(__last), __find_segment<_Tp>(__value), __proj); 154 } 155 156 template <class _Tp> 157 struct __find_segment { 158 const _Tp& __value_; 159 160 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR __find_segment(const _Tp& __value) : __value_(__value) {} 161 162 template <class _InputIterator, class _Proj> 163 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR _InputIterator 164 operator()(_InputIterator __first, _InputIterator __last, _Proj& __proj) const { 165 return std::__find(__first, __last, __value_, __proj); 166 } 167 }; 168 169 // public API 170 template <class _InputIterator, class _Tp> 171 [[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _InputIterator 172 find(_InputIterator __first, _InputIterator __last, const _Tp& __value) { 173 __identity __proj; 174 return std::__rewrap_iter( 175 __first, std::__find(std::__unwrap_iter(__first), std::__unwrap_iter(__last), __value, __proj)); 176 } 177 178 _LIBCPP_END_NAMESPACE_STD 179 180 _LIBCPP_POP_MACROS 181 182 #endif // _LIBCPP___ALGORITHM_FIND_H 183