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_same.h> 25 #include <__utility/move.h> 26 27 #ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS 28 # include <cwchar> 29 #endif 30 31 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 32 # pragma GCC system_header 33 #endif 34 35 _LIBCPP_PUSH_MACROS 36 #include <__undef_macros> 37 38 _LIBCPP_BEGIN_NAMESPACE_STD 39 40 // generic implementation 41 template <class _Iter, class _Sent, class _Tp, class _Proj> 42 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Iter 43 __find_impl(_Iter __first, _Sent __last, const _Tp& __value, _Proj& __proj) { 44 for (; __first != __last; ++__first) 45 if (std::__invoke(__proj, *__first) == __value) 46 break; 47 return __first; 48 } 49 50 // trivially equality comparable implementations 51 template <class _Tp, 52 class _Up, 53 class _Proj, 54 __enable_if_t<__is_identity<_Proj>::value && __libcpp_is_trivially_equality_comparable<_Tp, _Up>::value && 55 sizeof(_Tp) == 1, 56 int> = 0> 57 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Tp* 58 __find_impl(_Tp* __first, _Tp* __last, const _Up& __value, _Proj&) { 59 if (auto __ret = std::__constexpr_memchr(__first, __value, __last - __first)) 60 return __ret; 61 return __last; 62 } 63 64 #ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS 65 template <class _Tp, 66 class _Up, 67 class _Proj, 68 __enable_if_t<__is_identity<_Proj>::value && __libcpp_is_trivially_equality_comparable<_Tp, _Up>::value && 69 sizeof(_Tp) == sizeof(wchar_t) && _LIBCPP_ALIGNOF(_Tp) >= _LIBCPP_ALIGNOF(wchar_t), 70 int> = 0> 71 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Tp* 72 __find_impl(_Tp* __first, _Tp* __last, const _Up& __value, _Proj&) { 73 if (auto __ret = std::__constexpr_wmemchr(__first, __value, __last - __first)) 74 return __ret; 75 return __last; 76 } 77 #endif // _LIBCPP_HAS_NO_WIDE_CHARACTERS 78 79 // __bit_iterator implementation 80 template <bool _ToFind, class _Cp, bool _IsConst> 81 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI __bit_iterator<_Cp, _IsConst> 82 __find_bool(__bit_iterator<_Cp, _IsConst> __first, typename _Cp::size_type __n) { 83 using _It = __bit_iterator<_Cp, _IsConst>; 84 using __storage_type = typename _It::__storage_type; 85 86 const int __bits_per_word = _It::__bits_per_word; 87 // do first partial word 88 if (__first.__ctz_ != 0) { 89 __storage_type __clz_f = static_cast<__storage_type>(__bits_per_word - __first.__ctz_); 90 __storage_type __dn = std::min(__clz_f, __n); 91 __storage_type __m = (~__storage_type(0) << __first.__ctz_) & (~__storage_type(0) >> (__clz_f - __dn)); 92 __storage_type __b = std::__invert_if<!_ToFind>(*__first.__seg_) & __m; 93 if (__b) 94 return _It(__first.__seg_, static_cast<unsigned>(std::__libcpp_ctz(__b))); 95 if (__n == __dn) 96 return __first + __n; 97 __n -= __dn; 98 ++__first.__seg_; 99 } 100 // do middle whole words 101 for (; __n >= __bits_per_word; ++__first.__seg_, __n -= __bits_per_word) { 102 __storage_type __b = std::__invert_if<!_ToFind>(*__first.__seg_); 103 if (__b) 104 return _It(__first.__seg_, static_cast<unsigned>(std::__libcpp_ctz(__b))); 105 } 106 // do last partial word 107 if (__n > 0) { 108 __storage_type __m = ~__storage_type(0) >> (__bits_per_word - __n); 109 __storage_type __b = std::__invert_if<!_ToFind>(*__first.__seg_) & __m; 110 if (__b) 111 return _It(__first.__seg_, static_cast<unsigned>(std::__libcpp_ctz(__b))); 112 } 113 return _It(__first.__seg_, static_cast<unsigned>(__n)); 114 } 115 116 template <class _Cp, bool _IsConst, class _Tp, class _Proj, __enable_if_t<__is_identity<_Proj>::value, int> = 0> 117 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 __bit_iterator<_Cp, _IsConst> 118 __find_impl(__bit_iterator<_Cp, _IsConst> __first, __bit_iterator<_Cp, _IsConst> __last, const _Tp& __value, _Proj&) { 119 if (static_cast<bool>(__value)) 120 return std::__find_bool<true>(__first, static_cast<typename _Cp::size_type>(__last - __first)); 121 return std::__find_bool<false>(__first, static_cast<typename _Cp::size_type>(__last - __first)); 122 } 123 124 // segmented iterator implementation 125 126 template <class> 127 struct __find_segment; 128 129 template <class _SegmentedIterator, 130 class _Tp, 131 class _Proj, 132 __enable_if_t<__is_segmented_iterator<_SegmentedIterator>::value, int> = 0> 133 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _SegmentedIterator 134 __find_impl(_SegmentedIterator __first, _SegmentedIterator __last, const _Tp& __value, _Proj& __proj) { 135 return std::__find_segment_if(std::move(__first), std::move(__last), __find_segment<_Tp>(__value), __proj); 136 } 137 138 template <class _Tp> 139 struct __find_segment { 140 const _Tp& __value_; 141 142 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR __find_segment(const _Tp& __value) : __value_(__value) {} 143 144 template <class _InputIterator, class _Proj> 145 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR _InputIterator 146 operator()(_InputIterator __first, _InputIterator __last, _Proj& __proj) const { 147 return std::__find_impl(__first, __last, __value_, __proj); 148 } 149 }; 150 151 // public API 152 template <class _InputIterator, class _Tp> 153 _LIBCPP_NODISCARD_EXT inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _InputIterator 154 find(_InputIterator __first, _InputIterator __last, const _Tp& __value) { 155 __identity __proj; 156 return std::__rewrap_iter( 157 __first, std::__find_impl(std::__unwrap_iter(__first), std::__unwrap_iter(__last), __value, __proj)); 158 } 159 160 _LIBCPP_END_NAMESPACE_STD 161 162 _LIBCPP_POP_MACROS 163 164 #endif // _LIBCPP___ALGORITHM_FIND_H 165