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