libcxx/include/__cxx03/__algorithm/find.h

   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 <__cxx03/__algorithm/find_segment_if.h>
  14 #include <__cxx03/__algorithm/min.h>
  15 #include <__cxx03/__algorithm/unwrap_iter.h>
  16 #include <__cxx03/__bit/countr.h>
  17 #include <__cxx03/__bit/invert_if.h>
  18 #include <__cxx03/__config>
  19 #include <__cxx03/__functional/identity.h>
  20 #include <__cxx03/__functional/invoke.h>
  21 #include <__cxx03/__fwd/bit_reference.h>
  22 #include <__cxx03/__iterator/segmented_iterator.h>
  23 #include <__cxx03/__string/constexpr_c_functions.h>
  24 #include <__cxx03/__type_traits/is_integral.h>
  25 #include <__cxx03/__type_traits/is_same.h>
  26 #include <__cxx03/__type_traits/is_signed.h>
  27 #include <__cxx03/__utility/move.h>
  28 #include <__cxx03/limits>
  29
  30 #ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
  31 #  include <__cxx03/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 <__cxx03/__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(_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* __find(_Tp* __first, _Tp* __last, const _Up& __value, _Proj&) {
  61   if (auto __ret = std::__constexpr_memchr(__first, __value, __last - __first))
  62     return __ret;
  63   return __last;
  64 }
  65
  66 #ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
  67 template <class _Tp,
  68           class _Up,
  69           class _Proj,
  70           __enable_if_t<__is_identity<_Proj>::value && __libcpp_is_trivially_equality_comparable<_Tp, _Up>::value &&
  71                             sizeof(_Tp) == sizeof(wchar_t) && _LIBCPP_ALIGNOF(_Tp) >= _LIBCPP_ALIGNOF(wchar_t),
  72                         int> = 0>
  73 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Tp* __find(_Tp* __first, _Tp* __last, const _Up& __value, _Proj&) {
  74   if (auto __ret = std::__constexpr_wmemchr(__first, __value, __last - __first))
  75     return __ret;
  76   return __last;
  77 }
  78 #endif // _LIBCPP_HAS_NO_WIDE_CHARACTERS
  79
  80 // TODO: This should also be possible to get right with different signedness
  81 // cast integral types to allow vectorization
  82 template <class _Tp,
  83           class _Up,
  84           class _Proj,
  85           __enable_if_t<__is_identity<_Proj>::value && !__libcpp_is_trivially_equality_comparable<_Tp, _Up>::value &&
  86                             is_integral<_Tp>::value && is_integral<_Up>::value &&
  87                             is_signed<_Tp>::value == is_signed<_Up>::value,
  88                         int> = 0>
  89 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Tp*
  90 __find(_Tp* __first, _Tp* __last, const _Up& __value, _Proj& __proj) {
  91   if (__value < numeric_limits<_Tp>::min() || __value > numeric_limits<_Tp>::max())
  92     return __last;
  93   return std::__find(__first, __last, _Tp(__value), __proj);
  94 }
  95
  96 // __bit_iterator implementation
  97 template <bool _ToFind, class _Cp, bool _IsConst>
  98 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI __bit_iterator<_Cp, _IsConst>
  99 __find_bool(__bit_iterator<_Cp, _IsConst> __first, typename _Cp::size_type __n) {
 100   using _It            = __bit_iterator<_Cp, _IsConst>;
 101   using __storage_type = typename _It::__storage_type;
 102
 103   const int __bits_per_word = _It::__bits_per_word;
 104   // do first partial word
 105   if (__first.__ctz_ != 0) {
 106     __storage_type __clz_f = static_cast<__storage_type>(__bits_per_word - __first.__ctz_);
 107     __storage_type __dn    = std::min(__clz_f, __n);
 108     __storage_type __m     = (~__storage_type(0) << __first.__ctz_) & (~__storage_type(0) >> (__clz_f - __dn));
 109     __storage_type __b     = std::__invert_if<!_ToFind>(*__first.__seg_) & __m;
 110     if (__b)
 111       return _It(__first.__seg_, static_cast<unsigned>(std::__libcpp_ctz(__b)));
 112     if (__n == __dn)
 113       return __first + __n;
 114     __n -= __dn;
 115     ++__first.__seg_;
 116   }
 117   // do middle whole words
 118   for (; __n >= __bits_per_word; ++__first.__seg_, __n -= __bits_per_word) {
 119     __storage_type __b = std::__invert_if<!_ToFind>(*__first.__seg_);
 120     if (__b)
 121       return _It(__first.__seg_, static_cast<unsigned>(std::__libcpp_ctz(__b)));
 122   }
 123   // do last partial word
 124   if (__n > 0) {
 125     __storage_type __m = ~__storage_type(0) >> (__bits_per_word - __n);
 126     __storage_type __b = std::__invert_if<!_ToFind>(*__first.__seg_) & __m;
 127     if (__b)
 128       return _It(__first.__seg_, static_cast<unsigned>(std::__libcpp_ctz(__b)));
 129   }
 130   return _It(__first.__seg_, static_cast<unsigned>(__n));
 131 }
 132
 133 template <class _Cp, bool _IsConst, class _Tp, class _Proj, __enable_if_t<__is_identity<_Proj>::value, int> = 0>
 134 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 __bit_iterator<_Cp, _IsConst>
 135 __find(__bit_iterator<_Cp, _IsConst> __first, __bit_iterator<_Cp, _IsConst> __last, const _Tp& __value, _Proj&) {
 136   if (static_cast<bool>(__value))
 137     return std::__find_bool<true>(__first, static_cast<typename _Cp::size_type>(__last - __first));
 138   return std::__find_bool<false>(__first, static_cast<typename _Cp::size_type>(__last - __first));
 139 }
 140
 141 // segmented iterator implementation
 142
 143 template <class>
 144 struct __find_segment;
 145
 146 template <class _SegmentedIterator,
 147           class _Tp,
 148           class _Proj,
 149           __enable_if_t<__is_segmented_iterator<_SegmentedIterator>::value, int> = 0>
 150 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _SegmentedIterator
 151 __find(_SegmentedIterator __first, _SegmentedIterator __last, const _Tp& __value, _Proj& __proj) {
 152   return std::__find_segment_if(std::move(__first), std::move(__last), __find_segment<_Tp>(__value), __proj);
 153 }
 154
 155 template <class _Tp>
 156 struct __find_segment {
 157   const _Tp& __value_;
 158
 159   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR __find_segment(const _Tp& __value) : __value_(__value) {}
 160
 161   template <class _InputIterator, class _Proj>
 162   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR _InputIterator
 163   operator()(_InputIterator __first, _InputIterator __last, _Proj& __proj) const {
 164     return std::__find(__first, __last, __value_, __proj);
 165   }
 166 };
 167
 168 // public API
 169 template <class _InputIterator, class _Tp>
 170 _LIBCPP_NODISCARD inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _InputIterator
 171 find(_InputIterator __first, _InputIterator __last, const _Tp& __value) {
 172   __identity __proj;
 173   return std::__rewrap_iter(
 174       __first, std::__find(std::__unwrap_iter(__first), std::__unwrap_iter(__last), __value, __proj));
 175 }
 176
 177 _LIBCPP_END_NAMESPACE_STD
 178
 179 _LIBCPP_POP_MACROS
 180
 181 #endif // _LIBCPP___ALGORITHM_FIND_H