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_COUNT_H 11 #define _LIBCPP___ALGORITHM_COUNT_H 12 13 #include <__algorithm/iterator_operations.h> 14 #include <__algorithm/min.h> 15 #include <__bit/invert_if.h> 16 #include <__bit/popcount.h> 17 #include <__config> 18 #include <__functional/identity.h> 19 #include <__fwd/bit_reference.h> 20 #include <__iterator/iterator_traits.h> 21 #include <__type_traits/enable_if.h> 22 #include <__type_traits/invoke.h> 23 24 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 25 # pragma GCC system_header 26 #endif 27 28 _LIBCPP_PUSH_MACROS 29 #include <__undef_macros> 30 31 _LIBCPP_BEGIN_NAMESPACE_STD 32 33 // generic implementation 34 template <class _AlgPolicy, class _Iter, class _Sent, class _Tp, class _Proj> 35 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 typename _IterOps<_AlgPolicy>::template __difference_type<_Iter> 36 __count(_Iter __first, _Sent __last, const _Tp& __value, _Proj& __proj) { 37 typename _IterOps<_AlgPolicy>::template __difference_type<_Iter> __r(0); 38 for (; __first != __last; ++__first) 39 if (std::__invoke(__proj, *__first) == __value) 40 ++__r; 41 return __r; 42 } 43 44 // __bit_iterator implementation 45 template <bool _ToCount, class _Cp, bool _IsConst> 46 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 typename __bit_iterator<_Cp, _IsConst>::difference_type 47 __count_bool(__bit_iterator<_Cp, _IsConst> __first, typename __size_difference_type_traits<_Cp>::size_type __n) { 48 using _It = __bit_iterator<_Cp, _IsConst>; 49 using __storage_type = typename _It::__storage_type; 50 using difference_type = typename _It::difference_type; 51 52 const int __bits_per_word = _It::__bits_per_word; 53 difference_type __r = 0; 54 // do first partial word 55 if (__first.__ctz_ != 0) { 56 __storage_type __clz_f = static_cast<__storage_type>(__bits_per_word - __first.__ctz_); 57 __storage_type __dn = std::min(__clz_f, __n); 58 __storage_type __m = (~__storage_type(0) << __first.__ctz_) & (~__storage_type(0) >> (__clz_f - __dn)); 59 __r = std::__libcpp_popcount(std::__invert_if<!_ToCount>(*__first.__seg_) & __m); 60 __n -= __dn; 61 ++__first.__seg_; 62 } 63 // do middle whole words 64 for (; __n >= __bits_per_word; ++__first.__seg_, __n -= __bits_per_word) 65 __r += std::__libcpp_popcount(std::__invert_if<!_ToCount>(*__first.__seg_)); 66 // do last partial word 67 if (__n > 0) { 68 __storage_type __m = ~__storage_type(0) >> (__bits_per_word - __n); 69 __r += std::__libcpp_popcount(std::__invert_if<!_ToCount>(*__first.__seg_) & __m); 70 } 71 return __r; 72 } 73 74 template <class, class _Cp, bool _IsConst, class _Tp, class _Proj, __enable_if_t<__is_identity<_Proj>::value, int> = 0> 75 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 __iter_diff_t<__bit_iterator<_Cp, _IsConst> > 76 __count(__bit_iterator<_Cp, _IsConst> __first, __bit_iterator<_Cp, _IsConst> __last, const _Tp& __value, _Proj&) { 77 if (__value) 78 return std::__count_bool<true>( 79 __first, static_cast<typename __size_difference_type_traits<_Cp>::size_type>(__last - __first)); 80 return std::__count_bool<false>( 81 __first, static_cast<typename __size_difference_type_traits<_Cp>::size_type>(__last - __first)); 82 } 83 84 template <class _InputIterator, class _Tp> 85 [[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 __iter_diff_t<_InputIterator> 86 count(_InputIterator __first, _InputIterator __last, const _Tp& __value) { 87 __identity __proj; 88 return std::__count<_ClassicAlgPolicy>(__first, __last, __value, __proj); 89 } 90 91 _LIBCPP_END_NAMESPACE_STD 92 93 _LIBCPP_POP_MACROS 94 95 #endif // _LIBCPP___ALGORITHM_COUNT_H 96