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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___CXX03___ALGORITHM_COUNT_H
11#define _LIBCPP___CXX03___ALGORITHM_COUNT_H
12
13#include <__cxx03/__algorithm/iterator_operations.h>
14#include <__cxx03/__algorithm/min.h>
15#include <__cxx03/__bit/invert_if.h>
16#include <__cxx03/__bit/popcount.h>
17#include <__cxx03/__config>
18#include <__cxx03/__functional/identity.h>
19#include <__cxx03/__fwd/bit_reference.h>
20#include <__cxx03/__iterator/iterator_traits.h>
21#include <__cxx03/__type_traits/invoke.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 <__cxx03/__undef_macros>
29
30_LIBCPP_BEGIN_NAMESPACE_STD
31
32// generic implementation
33template <class _AlgPolicy, class _Iter, class _Sent, class _Tp, class _Proj>
34_LIBCPP_HIDE_FROM_ABI 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
44template <bool _ToCount, class _Cp, bool _IsConst>
45_LIBCPP_HIDE_FROM_ABI 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
73template <class, class _Cp, bool _IsConst, class _Tp, class _Proj, __enable_if_t<__is_identity<_Proj>::value, int> = 0>
74_LIBCPP_HIDE_FROM_ABI __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
81template <class _InputIterator, class _Tp>
82_LIBCPP_NODISCARD inline _LIBCPP_HIDE_FROM_ABI __iter_diff_t<_InputIterator>
83count(_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___CXX03___ALGORITHM_COUNT_H
93

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source code of libcxx/include/__cxx03/__algorithm/count.h