xref: /freebsd/contrib/llvm-project/libcxx/include/__algorithm/find.h (revision a90b9d0159070121c221b966469c3e36d912bf82)
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_integral.h>
25 #include <__type_traits/is_same.h>
26 #include <__type_traits/is_signed.h>
27 #include <__utility/move.h>
28 #include <limits>
29 
30 #ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
31 #  include <cwchar>
32 #endif
33 
34 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
35 #  pragma GCC system_header
36 #endif
37 
38 _LIBCPP_PUSH_MACROS
39 #include <__undef_macros>
40 
41 _LIBCPP_BEGIN_NAMESPACE_STD
42 
43 // generic implementation
44 template <class _Iter, class _Sent, class _Tp, class _Proj>
45 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Iter
46 __find_impl(_Iter __first, _Sent __last, const _Tp& __value, _Proj& __proj) {
47   for (; __first != __last; ++__first)
48     if (std::__invoke(__proj, *__first) == __value)
49       break;
50   return __first;
51 }
52 
53 // trivially equality comparable implementations
54 template <class _Tp,
55           class _Up,
56           class _Proj,
57           __enable_if_t<__is_identity<_Proj>::value && __libcpp_is_trivially_equality_comparable<_Tp, _Up>::value &&
58                             sizeof(_Tp) == 1,
59                         int> = 0>
60 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Tp*
61 __find_impl(_Tp* __first, _Tp* __last, const _Up& __value, _Proj&) {
62   if (auto __ret = std::__constexpr_memchr(__first, __value, __last - __first))
63     return __ret;
64   return __last;
65 }
66 
67 #ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
68 template <class _Tp,
69           class _Up,
70           class _Proj,
71           __enable_if_t<__is_identity<_Proj>::value && __libcpp_is_trivially_equality_comparable<_Tp, _Up>::value &&
72                             sizeof(_Tp) == sizeof(wchar_t) && _LIBCPP_ALIGNOF(_Tp) >= _LIBCPP_ALIGNOF(wchar_t),
73                         int> = 0>
74 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Tp*
75 __find_impl(_Tp* __first, _Tp* __last, const _Up& __value, _Proj&) {
76   if (auto __ret = std::__constexpr_wmemchr(__first, __value, __last - __first))
77     return __ret;
78   return __last;
79 }
80 #endif // _LIBCPP_HAS_NO_WIDE_CHARACTERS
81 
82 // TODO: This should also be possible to get right with different signedness
83 // cast integral types to allow vectorization
84 template <class _Tp,
85           class _Up,
86           class _Proj,
87           __enable_if_t<__is_identity<_Proj>::value && !__libcpp_is_trivially_equality_comparable<_Tp, _Up>::value &&
88                             is_integral<_Tp>::value && is_integral<_Up>::value &&
89                             is_signed<_Tp>::value == is_signed<_Up>::value,
90                         int> = 0>
91 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Tp*
92 __find_impl(_Tp* __first, _Tp* __last, const _Up& __value, _Proj& __proj) {
93   if (__value < numeric_limits<_Tp>::min() || __value > numeric_limits<_Tp>::max())
94     return __last;
95   return std::__find_impl(__first, __last, _Tp(__value), __proj);
96 }
97 
98 // __bit_iterator implementation
99 template <bool _ToFind, class _Cp, bool _IsConst>
100 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI __bit_iterator<_Cp, _IsConst>
101 __find_bool(__bit_iterator<_Cp, _IsConst> __first, typename _Cp::size_type __n) {
102   using _It            = __bit_iterator<_Cp, _IsConst>;
103   using __storage_type = typename _It::__storage_type;
104 
105   const int __bits_per_word = _It::__bits_per_word;
106   // do first partial word
107   if (__first.__ctz_ != 0) {
108     __storage_type __clz_f = static_cast<__storage_type>(__bits_per_word - __first.__ctz_);
109     __storage_type __dn    = std::min(__clz_f, __n);
110     __storage_type __m     = (~__storage_type(0) << __first.__ctz_) & (~__storage_type(0) >> (__clz_f - __dn));
111     __storage_type __b     = std::__invert_if<!_ToFind>(*__first.__seg_) & __m;
112     if (__b)
113       return _It(__first.__seg_, static_cast<unsigned>(std::__libcpp_ctz(__b)));
114     if (__n == __dn)
115       return __first + __n;
116     __n -= __dn;
117     ++__first.__seg_;
118   }
119   // do middle whole words
120   for (; __n >= __bits_per_word; ++__first.__seg_, __n -= __bits_per_word) {
121     __storage_type __b = std::__invert_if<!_ToFind>(*__first.__seg_);
122     if (__b)
123       return _It(__first.__seg_, static_cast<unsigned>(std::__libcpp_ctz(__b)));
124   }
125   // do last partial word
126   if (__n > 0) {
127     __storage_type __m = ~__storage_type(0) >> (__bits_per_word - __n);
128     __storage_type __b = std::__invert_if<!_ToFind>(*__first.__seg_) & __m;
129     if (__b)
130       return _It(__first.__seg_, static_cast<unsigned>(std::__libcpp_ctz(__b)));
131   }
132   return _It(__first.__seg_, static_cast<unsigned>(__n));
133 }
134 
135 template <class _Cp, bool _IsConst, class _Tp, class _Proj, __enable_if_t<__is_identity<_Proj>::value, int> = 0>
136 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 __bit_iterator<_Cp, _IsConst>
137 __find_impl(__bit_iterator<_Cp, _IsConst> __first, __bit_iterator<_Cp, _IsConst> __last, const _Tp& __value, _Proj&) {
138   if (static_cast<bool>(__value))
139     return std::__find_bool<true>(__first, static_cast<typename _Cp::size_type>(__last - __first));
140   return std::__find_bool<false>(__first, static_cast<typename _Cp::size_type>(__last - __first));
141 }
142 
143 // segmented iterator implementation
144 
145 template <class>
146 struct __find_segment;
147 
148 template <class _SegmentedIterator,
149           class _Tp,
150           class _Proj,
151           __enable_if_t<__is_segmented_iterator<_SegmentedIterator>::value, int> = 0>
152 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _SegmentedIterator
153 __find_impl(_SegmentedIterator __first, _SegmentedIterator __last, const _Tp& __value, _Proj& __proj) {
154   return std::__find_segment_if(std::move(__first), std::move(__last), __find_segment<_Tp>(__value), __proj);
155 }
156 
157 template <class _Tp>
158 struct __find_segment {
159   const _Tp& __value_;
160 
161   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR __find_segment(const _Tp& __value) : __value_(__value) {}
162 
163   template <class _InputIterator, class _Proj>
164   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR _InputIterator
165   operator()(_InputIterator __first, _InputIterator __last, _Proj& __proj) const {
166     return std::__find_impl(__first, __last, __value_, __proj);
167   }
168 };
169 
170 // public API
171 template <class _InputIterator, class _Tp>
172 _LIBCPP_NODISCARD_EXT inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _InputIterator
173 find(_InputIterator __first, _InputIterator __last, const _Tp& __value) {
174   __identity __proj;
175   return std::__rewrap_iter(
176       __first, std::__find_impl(std::__unwrap_iter(__first), std::__unwrap_iter(__last), __value, __proj));
177 }
178 
179 _LIBCPP_END_NAMESPACE_STD
180 
181 _LIBCPP_POP_MACROS
182 
183 #endif // _LIBCPP___ALGORITHM_FIND_H
184