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 <__functional/invoke.h> 21 #include <__fwd/bit_reference.h> 22 #include <__iterator/segmented_iterator.h> 23 #include <__string/constexpr_c_functions.h> 24 #include <__type_traits/is_integral.h> 25 #include <__type_traits/is_same.h> 26 #include <__type_traits/is_signed.h> 27 #include <__utility/move.h> 28 #include <limits> 29 30 #ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS 31 # include <cwchar> 32 #endif 33 34 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 35 # pragma GCC system_header 36 #endif 37 38 _LIBCPP_PUSH_MACROS 39 #include <__undef_macros> 40 41 _LIBCPP_BEGIN_NAMESPACE_STD 42 43 // generic implementation 44 template <class _Iter, class _Sent, class _Tp, class _Proj> 45 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Iter 46 __find_impl(_Iter __first, _Sent __last, const _Tp& __value, _Proj& __proj) { 47 for (; __first != __last; ++__first) 48 if (std::__invoke(__proj, *__first) == __value) 49 break; 50 return __first; 51 } 52 53 // trivially equality comparable implementations 54 template <class _Tp, 55 class _Up, 56 class _Proj, 57 __enable_if_t<__is_identity<_Proj>::value && __libcpp_is_trivially_equality_comparable<_Tp, _Up>::value && 58 sizeof(_Tp) == 1, 59 int> = 0> 60 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Tp* 61 __find_impl(_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 #ifndef _LIBCPP_HAS_NO_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* 75 __find_impl(_Tp* __first, _Tp* __last, const _Up& __value, _Proj&) { 76 if (auto __ret = std::__constexpr_wmemchr(__first, __value, __last - __first)) 77 return __ret; 78 return __last; 79 } 80 #endif // _LIBCPP_HAS_NO_WIDE_CHARACTERS 81 82 // TODO: This should also be possible to get right with different signedness 83 // cast integral types to allow vectorization 84 template <class _Tp, 85 class _Up, 86 class _Proj, 87 __enable_if_t<__is_identity<_Proj>::value && !__libcpp_is_trivially_equality_comparable<_Tp, _Up>::value && 88 is_integral<_Tp>::value && is_integral<_Up>::value && 89 is_signed<_Tp>::value == is_signed<_Up>::value, 90 int> = 0> 91 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Tp* 92 __find_impl(_Tp* __first, _Tp* __last, const _Up& __value, _Proj& __proj) { 93 if (__value < numeric_limits<_Tp>::min() || __value > numeric_limits<_Tp>::max()) 94 return __last; 95 return std::__find_impl(__first, __last, _Tp(__value), __proj); 96 } 97 98 // __bit_iterator implementation 99 template <bool _ToFind, class _Cp, bool _IsConst> 100 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI __bit_iterator<_Cp, _IsConst> 101 __find_bool(__bit_iterator<_Cp, _IsConst> __first, typename _Cp::size_type __n) { 102 using _It = __bit_iterator<_Cp, _IsConst>; 103 using __storage_type = typename _It::__storage_type; 104 105 const int __bits_per_word = _It::__bits_per_word; 106 // do first partial word 107 if (__first.__ctz_ != 0) { 108 __storage_type __clz_f = static_cast<__storage_type>(__bits_per_word - __first.__ctz_); 109 __storage_type __dn = std::min(__clz_f, __n); 110 __storage_type __m = (~__storage_type(0) << __first.__ctz_) & (~__storage_type(0) >> (__clz_f - __dn)); 111 __storage_type __b = std::__invert_if<!_ToFind>(*__first.__seg_) & __m; 112 if (__b) 113 return _It(__first.__seg_, static_cast<unsigned>(std::__libcpp_ctz(__b))); 114 if (__n == __dn) 115 return __first + __n; 116 __n -= __dn; 117 ++__first.__seg_; 118 } 119 // do middle whole words 120 for (; __n >= __bits_per_word; ++__first.__seg_, __n -= __bits_per_word) { 121 __storage_type __b = std::__invert_if<!_ToFind>(*__first.__seg_); 122 if (__b) 123 return _It(__first.__seg_, static_cast<unsigned>(std::__libcpp_ctz(__b))); 124 } 125 // do last partial word 126 if (__n > 0) { 127 __storage_type __m = ~__storage_type(0) >> (__bits_per_word - __n); 128 __storage_type __b = std::__invert_if<!_ToFind>(*__first.__seg_) & __m; 129 if (__b) 130 return _It(__first.__seg_, static_cast<unsigned>(std::__libcpp_ctz(__b))); 131 } 132 return _It(__first.__seg_, static_cast<unsigned>(__n)); 133 } 134 135 template <class _Cp, bool _IsConst, class _Tp, class _Proj, __enable_if_t<__is_identity<_Proj>::value, int> = 0> 136 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 __bit_iterator<_Cp, _IsConst> 137 __find_impl(__bit_iterator<_Cp, _IsConst> __first, __bit_iterator<_Cp, _IsConst> __last, const _Tp& __value, _Proj&) { 138 if (static_cast<bool>(__value)) 139 return std::__find_bool<true>(__first, static_cast<typename _Cp::size_type>(__last - __first)); 140 return std::__find_bool<false>(__first, static_cast<typename _Cp::size_type>(__last - __first)); 141 } 142 143 // segmented iterator implementation 144 145 template <class> 146 struct __find_segment; 147 148 template <class _SegmentedIterator, 149 class _Tp, 150 class _Proj, 151 __enable_if_t<__is_segmented_iterator<_SegmentedIterator>::value, int> = 0> 152 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _SegmentedIterator 153 __find_impl(_SegmentedIterator __first, _SegmentedIterator __last, const _Tp& __value, _Proj& __proj) { 154 return std::__find_segment_if(std::move(__first), std::move(__last), __find_segment<_Tp>(__value), __proj); 155 } 156 157 template <class _Tp> 158 struct __find_segment { 159 const _Tp& __value_; 160 161 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR __find_segment(const _Tp& __value) : __value_(__value) {} 162 163 template <class _InputIterator, class _Proj> 164 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR _InputIterator 165 operator()(_InputIterator __first, _InputIterator __last, _Proj& __proj) const { 166 return std::__find_impl(__first, __last, __value_, __proj); 167 } 168 }; 169 170 // public API 171 template <class _InputIterator, class _Tp> 172 _LIBCPP_NODISCARD_EXT inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _InputIterator 173 find(_InputIterator __first, _InputIterator __last, const _Tp& __value) { 174 __identity __proj; 175 return std::__rewrap_iter( 176 __first, std::__find_impl(std::__unwrap_iter(__first), std::__unwrap_iter(__last), __value, __proj)); 177 } 178 179 _LIBCPP_END_NAMESPACE_STD 180 181 _LIBCPP_POP_MACROS 182 183 #endif // _LIBCPP___ALGORITHM_FIND_H 184