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
34template <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
45template <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     = std::__middle_mask<__storage_type>(__clz_f - __dn, __first.__ctz_);
59    __r                    = std::__popcount(__storage_type(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::__popcount(std::__invert_if<!_ToCount>(*__first.__seg_));
66  // do last partial word
67  if (__n > 0) {
68    __storage_type __m = std::__trailing_mask<__storage_type>(__bits_per_word - __n);
69    __r += std::__popcount(__storage_type(std::__invert_if<!_ToCount>(*__first.__seg_) & __m));
70  }
71  return __r;
72}
73
74template <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
84template <class _InputIterator, class _Tp>
85[[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 __iter_diff_t<_InputIterator>
86count(_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