include/__algorithm/find.h - llvm-project/libcxx - Git at Google

 // -*- C++ -*-
 //===----------------------------------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//

 #ifndef _LIBCPP___ALGORITHM_FIND_H
 #define _LIBCPP___ALGORITHM_FIND_H

 #include <__algorithm/find_segment_if.h>
 #include <__algorithm/min.h>
 #include <__algorithm/simd_utils.h>
 #include <__algorithm/unwrap_iter.h>
 #include <__bit/countr.h>
 #include <__bit/invert_if.h>
 #include <__config>
 #include <__cstddef/size_t.h>
 #include <__functional/identity.h>
 #include <__fwd/bit_reference.h>
 #include <__iterator/segmented_iterator.h>
 #include <__string/constexpr_c_functions.h>
 #include <__type_traits/enable_if.h>
 #include <__type_traits/invoke.h>
 #include <__type_traits/is_constant_evaluated.h>
 #include <__type_traits/is_equality_comparable.h>
 #include <__type_traits/is_integral.h>
 #include <__type_traits/is_signed.h>
 #include <__utility/move.h>
 #include <limits>

 #if _LIBCPP_HAS_WIDE_CHARACTERS
 #  include <cwchar>
 #endif

 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #  pragma GCC system_header
 #endif

 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>

 _LIBCPP_BEGIN_NAMESPACE_STD

 // generic implementation
 template <class _Iter, class _Sent, class _Tp, class _Proj>
 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Iter
 __find_loop(_Iter __first, _Sent __last, const _Tp& __value, _Proj& __proj) {
   for (; __first != __last; ++__first)
     if (std::__invoke(__proj, *__first) == __value)
       break;
   return __first;
 }

 template <class _Iter, class _Sent, class _Tp, class _Proj>
 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Iter
 __find(_Iter __first, _Sent __last, const _Tp& __value, _Proj& __proj) {
   return std::__find_loop(std::move(__first), std::move(__last), __value, __proj);
 }

 #if _LIBCPP_VECTORIZE_ALGORITHMS
 template <class _Tp, class _Up>
 [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI
 _LIBCPP_CONSTEXPR_SINCE_CXX14 _Tp* __find_vectorized(_Tp* __first, _Tp* __last, _Up __value) {
   if (!__libcpp_is_constant_evaluated()) {
     constexpr size_t __unroll_count = 4;
     constexpr size_t __vec_size     = __native_vector_size<_Tp>;
     using __vec                     = __simd_vector<_Tp, __vec_size>;

     auto __orig_first = __first;

     auto __values = static_cast<__simd_vector<_Tp, __vec_size>>(__value); // broadcast the value
     while (static_cast<size_t>(__last - __first) >= __unroll_count * __vec_size) [[__unlikely__]] {
       __vec __lhs[__unroll_count];

       for (size_t __i = 0; __i != __unroll_count; ++__i)
         __lhs[__i] = std::__load_vector<__vec>(__first + __i * __vec_size);

       for (size_t __i = 0; __i != __unroll_count; ++__i) {
         if (auto __cmp_res = __lhs[__i] == __values; std::__any_of(__cmp_res)) {
           auto __offset = __i * __vec_size + std::__find_first_set(__cmp_res);
           return __first + __offset;
         }
       }

       __first += __unroll_count * __vec_size;
     }

     // check the remaining 0-3 vectors
     while (static_cast<size_t>(__last - __first) >= __vec_size) {
       if (auto __cmp_res = std::__load_vector<__vec>(__first) == __values; std::__any_of(__cmp_res)) {
         return __first + std::__find_first_set(__cmp_res);
       }
       __first += __vec_size;
     }

     if (__last - __first == 0)
       return __first;

     // Check if we can load elements in front of the current pointer. If that's the case load a vector at
     // (last - vector_size) to check the remaining elements
     if (static_cast<size_t>(__first - __orig_first) >= __vec_size) {
       __first = __last - __vec_size;
       return __first + std::__find_first_set(std::__load_vector<__vec>(__first) == __values);
     }
   }

   __identity __proj;
   return std::__find_loop(__first, __last, __value, __proj);
 }
 #endif

 #ifndef _LIBCPP_CXX03_LANG
 // trivially equality comparable implementations
 template <
     class _Tp,
     class _Up,
     class _Proj,
     __enable_if_t<__is_identity<_Proj>::value && __libcpp_is_trivially_equality_comparable<_Tp, _Up>::value, int> = 0>
 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Tp* __find(_Tp* __first, _Tp* __last, const _Up& __value, _Proj&) {
   if constexpr (sizeof(_Tp) == 1) {
     if (auto __ret = std::__constexpr_memchr(__first, __value, __last - __first))
       return __ret;
     return __last;
   }
 #  if _LIBCPP_HAS_WIDE_CHARACTERS
   else if constexpr (sizeof(_Tp) == sizeof(wchar_t) && _LIBCPP_ALIGNOF(_Tp) >= _LIBCPP_ALIGNOF(wchar_t)) {
     if (auto __ret = std::__constexpr_wmemchr(__first, __value, __last - __first))
       return __ret;
     return __last;
   }
 #  endif
 #  if _LIBCPP_VECTORIZE_ALGORITHMS
   else if constexpr (is_integral<_Tp>::value) {
     return std::__find_vectorized(__first, __last, __value);
   }
 #  endif
   else {
     __identity __proj;
     return std::__find_loop(__first, __last, __value, __proj);
   }
 }
 #endif

 // TODO: This should also be possible to get right with different signedness
 // cast integral types to allow vectorization
 template <class _Tp,
           class _Up,
           class _Proj,
           __enable_if_t<__is_identity<_Proj>::value && !__libcpp_is_trivially_equality_comparable<_Tp, _Up>::value &&
                             is_integral<_Tp>::value && is_integral<_Up>::value &&
                             is_signed<_Tp>::value == is_signed<_Up>::value,
                         int> = 0>
 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Tp*
 __find(_Tp* __first, _Tp* __last, const _Up& __value, _Proj& __proj) {
   if (__value < numeric_limits<_Tp>::min() || __value > numeric_limits<_Tp>::max())
     return __last;
   return std::__find(__first, __last, _Tp(__value), __proj);
 }

 // __bit_iterator implementation
 template <bool _ToFind, class _Cp, bool _IsConst>
 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI __bit_iterator<_Cp, _IsConst>
 __find_bool(__bit_iterator<_Cp, _IsConst> __first, typename __size_difference_type_traits<_Cp>::size_type __n) {
   using _It            = __bit_iterator<_Cp, _IsConst>;
   using __storage_type = typename _It::__storage_type;

   const int __bits_per_word = _It::__bits_per_word;
   // do first partial word
   if (__first.__ctz_ != 0) {
     __storage_type __clz_f = static_cast<__storage_type>(__bits_per_word - __first.__ctz_);
     __storage_type __dn    = std::min(__clz_f, __n);
     __storage_type __m     = std::__middle_mask<__storage_type>(__clz_f - __dn, __first.__ctz_);
     __storage_type __b     = std::__invert_if<!_ToFind>(*__first.__seg_) & __m;
     if (__b)
       return _It(__first.__seg_, static_cast<unsigned>(std::__countr_zero(__b)));
     if (__n == __dn)
       return __first + __n;
     __n -= __dn;
     ++__first.__seg_;
   }
   // do middle whole words
   for (; __n >= __bits_per_word; ++__first.__seg_, __n -= __bits_per_word) {
     __storage_type __b = std::__invert_if<!_ToFind>(*__first.__seg_);
     if (__b)
       return _It(__first.__seg_, static_cast<unsigned>(std::__countr_zero(__b)));
   }
   // do last partial word
   if (__n > 0) {
     __storage_type __m = std::__trailing_mask<__storage_type>(__bits_per_word - __n);
     __storage_type __b = std::__invert_if<!_ToFind>(*__first.__seg_) & __m;
     if (__b)
       return _It(__first.__seg_, static_cast<unsigned>(std::__countr_zero(__b)));
   }
   return _It(__first.__seg_, static_cast<unsigned>(__n));
 }

 template <class _Cp, bool _IsConst, class _Tp, class _Proj, __enable_if_t<__is_identity<_Proj>::value, int> = 0>
 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 __bit_iterator<_Cp, _IsConst>
 __find(__bit_iterator<_Cp, _IsConst> __first, __bit_iterator<_Cp, _IsConst> __last, const _Tp& __value, _Proj&) {
   if (static_cast<bool>(__value))
     return std::__find_bool<true>(
         __first, static_cast<typename __size_difference_type_traits<_Cp>::size_type>(__last - __first));
   return std::__find_bool<false>(
       __first, static_cast<typename __size_difference_type_traits<_Cp>::size_type>(__last - __first));
 }

 // segmented iterator implementation

 template <class>
 struct __find_segment;

 template <class _SegmentedIterator,
           class _Tp,
           class _Proj,
           __enable_if_t<__is_segmented_iterator_v<_SegmentedIterator>, int> = 0>
 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _SegmentedIterator
 __find(_SegmentedIterator __first, _SegmentedIterator __last, const _Tp& __value, _Proj& __proj) {
   return std::__find_segment_if(std::move(__first), std::move(__last), __find_segment<_Tp>(__value), __proj);
 }

 template <class _Tp>
 struct __find_segment {
   const _Tp& __value_;

   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR __find_segment(const _Tp& __value) : __value_(__value) {}

   template <class _InputIterator, class _Proj>
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR _InputIterator
   operator()(_InputIterator __first, _InputIterator __last, _Proj& __proj) const {
     return std::__find(__first, __last, __value_, __proj);
   }
 };

 // public API
 template <class _InputIterator, class _Tp>
 [[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _InputIterator
 find(_InputIterator __first, _InputIterator __last, const _Tp& __value) {
   __identity __proj;
   return std::__rewrap_iter(
       __first, std::__find(std::__unwrap_iter(__first), std::__unwrap_iter(__last), __value, __proj));
 }

 _LIBCPP_END_NAMESPACE_STD

 _LIBCPP_POP_MACROS

 #endif // _LIBCPP___ALGORITHM_FIND_H
	// -- C++ --
	//===----------------------------------------------------------------------===//
	//
	// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
	// See https://llvm.org/LICENSE.txt for license information.
	// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
	//
	//===----------------------------------------------------------------------===//

	#ifndef _LIBCPP___ALGORITHM_FIND_H
	#define _LIBCPP___ALGORITHM_FIND_H

	#include <__algorithm/find_segment_if.h>
	#include <__algorithm/min.h>
	#include <__algorithm/simd_utils.h>
	#include <__algorithm/unwrap_iter.h>
	#include <__bit/countr.h>
	#include <__bit/invert_if.h>
	#include <__config>
	#include <__cstddef/size_t.h>
	#include <__functional/identity.h>
	#include <__fwd/bit_reference.h>
	#include <__iterator/segmented_iterator.h>
	#include <__string/constexpr_c_functions.h>
	#include <__type_traits/enable_if.h>
	#include <__type_traits/invoke.h>
	#include <__type_traits/is_constant_evaluated.h>
	#include <__type_traits/is_equality_comparable.h>
	#include <__type_traits/is_integral.h>
	#include <__type_traits/is_signed.h>
	#include <__utility/move.h>
	#include <limits>

	#if _LIBCPP_HAS_WIDE_CHARACTERS
	# include <cwchar>
	#endif

	#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
	# pragma GCC system_header
	#endif

	_LIBCPP_PUSH_MACROS
	#include <__undef_macros>

	_LIBCPP_BEGIN_NAMESPACE_STD

	// generic implementation
	template <class _Iter, class _Sent, class _Tp, class _Proj>
	_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Iter
	__find_loop(_Iter __first, _Sent __last, const _Tp& __value, _Proj& __proj) {
	for (; __first != __last; ++__first)
	if (std::__invoke(__proj, *__first) == __value)
	break;
	return __first;
	}

	template <class _Iter, class _Sent, class _Tp, class _Proj>
	_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Iter
	__find(_Iter __first, _Sent __last, const _Tp& __value, _Proj& __proj) {
	return std::__find_loop(std::move(__first), std::move(__last), __value, __proj);
	}

	#if _LIBCPP_VECTORIZE_ALGORITHMS
	template <class _Tp, class _Up>
	[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI
	_LIBCPP_CONSTEXPR_SINCE_CXX14 _Tp* __find_vectorized(_Tp* __first, _Tp* __last, _Up __value) {
	if (!__libcpp_is_constant_evaluated()) {
	constexpr size_t __unroll_count = 4;
	constexpr size_t __vec_size = __native_vector_size<_Tp>;
	using __vec = __simd_vector<_Tp, __vec_size>;

	auto __orig_first = __first;

	auto __values = static_cast<__simd_vector<_Tp, __vec_size>>(__value); // broadcast the value
	while (static_cast<size_t>(__last - __first) >= __unroll_count * __vec_size) [[__unlikely__]] {
	__vec __lhs[__unroll_count];

	for (size_t __i = 0; __i != __unroll_count; ++__i)
	__lhs[__i] = std::__load_vector<__vec>(__first + __i * __vec_size);

	for (size_t __i = 0; __i != __unroll_count; ++__i) {
	if (auto __cmp_res = __lhs[__i] == __values; std::__any_of(__cmp_res)) {
	auto __offset = __i * __vec_size + std::__find_first_set(__cmp_res);
	return __first + __offset;
	}
	}

	__first += __unroll_count * __vec_size;
	}

	// check the remaining 0-3 vectors
	while (static_cast<size_t>(__last - __first) >= __vec_size) {
	if (auto __cmp_res = std::__load_vector<__vec>(__first) == __values; std::__any_of(__cmp_res)) {
	return __first + std::__find_first_set(__cmp_res);
	}
	__first += __vec_size;
	}

	if (__last - __first == 0)
	return __first;

	// Check if we can load elements in front of the current pointer. If that's the case load a vector at
	// (last - vector_size) to check the remaining elements
	if (static_cast<size_t>(__first - __orig_first) >= __vec_size) {
	__first = __last - __vec_size;
	return __first + std::__find_first_set(std::__load_vector<__vec>(__first) == __values);
	}
	}

	__identity __proj;
	return std::__find_loop(__first, __last, __value, __proj);
	}
	#endif

	#ifndef _LIBCPP_CXX03_LANG
	// trivially equality comparable implementations
	template <
	class _Tp,
	class _Up,
	class _Proj,
	__enable_if_t<__is_identity<_Proj>::value && __libcpp_is_trivially_equality_comparable<_Tp, _Up>::value, int> = 0>
	_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Tp* __find(_Tp* __first, _Tp* __last, const _Up& __value, _Proj&) {
	if constexpr (sizeof(_Tp) == 1) {
	if (auto __ret = std::__constexpr_memchr(__first, __value, __last - __first))
	return __ret;
	return __last;
	}
	# if _LIBCPP_HAS_WIDE_CHARACTERS
	else if constexpr (sizeof(_Tp) == sizeof(wchar_t) && _LIBCPP_ALIGNOF(_Tp) >= _LIBCPP_ALIGNOF(wchar_t)) {
	if (auto __ret = std::__constexpr_wmemchr(__first, __value, __last - __first))
	return __ret;
	return __last;
	}
	# endif
	# if _LIBCPP_VECTORIZE_ALGORITHMS
	else if constexpr (is_integral<_Tp>::value) {
	return std::__find_vectorized(__first, __last, __value);
	}
	# endif
	else {
	__identity __proj;
	return std::__find_loop(__first, __last, __value, __proj);
	}
	}
	#endif

	// TODO: This should also be possible to get right with different signedness
	// cast integral types to allow vectorization
	template <class _Tp,
	class _Up,
	class _Proj,
	__enable_if_t<__is_identity<_Proj>::value && !__libcpp_is_trivially_equality_comparable<_Tp, _Up>::value &&
	is_integral<_Tp>::value && is_integral<_Up>::value &&
	is_signed<_Tp>::value == is_signed<_Up>::value,
	int> = 0>
	_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Tp*
	__find(_Tp* __first, _Tp* __last, const _Up& __value, _Proj& __proj) {
	if (__value < numeric_limits<_Tp>::min() \|\| __value > numeric_limits<_Tp>::max())
	return __last;
	return std::__find(__first, __last, _Tp(__value), __proj);
	}

	// __bit_iterator implementation
	template <bool _ToFind, class _Cp, bool _IsConst>
	_LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI __bit_iterator<_Cp, _IsConst>
	__find_bool(__bit_iterator<_Cp, _IsConst> __first, typename __size_difference_type_traits<_Cp>::size_type __n) {
	using _It = __bit_iterator<_Cp, _IsConst>;
	using __storage_type = typename _It::__storage_type;

	const int __bits_per_word = _It::__bits_per_word;
	// do first partial word
	if (__first.__ctz_ != 0) {
	__storage_type __clz_f = static_cast<__storage_type>(__bits_per_word - __first.__ctz_);
	__storage_type __dn = std::min(__clz_f, __n);
	__storage_type __m = std::__middle_mask<__storage_type>(__clz_f - __dn, __first.__ctz_);
	__storage_type __b = std::__invert_if<!_ToFind>(*__first.__seg_) & __m;
	if (__b)
	return _It(__first.__seg_, static_cast<unsigned>(std::__countr_zero(__b)));
	if (__n == __dn)
	return __first + __n;
	__n -= __dn;
	++__first.__seg_;
	}
	// do middle whole words
	for (; __n >= __bits_per_word; ++__first.__seg_, __n -= __bits_per_word) {
	__storage_type __b = std::__invert_if<!_ToFind>(*__first.__seg_);
	if (__b)
	return _It(__first.__seg_, static_cast<unsigned>(std::__countr_zero(__b)));
	}
	// do last partial word
	if (__n > 0) {
	__storage_type __m = std::__trailing_mask<__storage_type>(__bits_per_word - __n);
	__storage_type __b = std::__invert_if<!_ToFind>(*__first.__seg_) & __m;
	if (__b)
	return _It(__first.__seg_, static_cast<unsigned>(std::__countr_zero(__b)));
	}
	return _It(__first.__seg_, static_cast<unsigned>(__n));
	}

	template <class _Cp, bool _IsConst, class _Tp, class _Proj, __enable_if_t<__is_identity<_Proj>::value, int> = 0>
	inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 __bit_iterator<_Cp, _IsConst>
	__find(__bit_iterator<_Cp, _IsConst> __first, __bit_iterator<_Cp, _IsConst> __last, const _Tp& __value, _Proj&) {
	if (static_cast<bool>(__value))
	return std::__find_bool<true>(
	__first, static_cast<typename __size_difference_type_traits<_Cp>::size_type>(__last - __first));
	return std::__find_bool<false>(
	__first, static_cast<typename __size_difference_type_traits<_Cp>::size_type>(__last - __first));
	}

	// segmented iterator implementation

	template <class>
	struct __find_segment;

	template <class _SegmentedIterator,
	class _Tp,
	class _Proj,
	__enable_if_t<__is_segmented_iterator_v<_SegmentedIterator>, int> = 0>
	_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _SegmentedIterator
	__find(_SegmentedIterator __first, _SegmentedIterator __last, const _Tp& __value, _Proj& __proj) {
	return std::__find_segment_if(std::move(__first), std::move(__last), __find_segment<_Tp>(__value), __proj);
	}

	template <class _Tp>
	struct __find_segment {
	const _Tp& __value_;

	_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR __find_segment(const _Tp& __value) : __value_(__value) {}

	template <class _InputIterator, class _Proj>
	_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR _InputIterator
	operator()(_InputIterator __first, _InputIterator __last, _Proj& __proj) const {
	return std::__find(__first, __last, __value_, __proj);
	}
	};

	// public API
	template <class _InputIterator, class _Tp>
	[[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _InputIterator
	find(_InputIterator __first, _InputIterator __last, const _Tp& __value) {
	__identity __proj;
	return std::__rewrap_iter(
	__first, std::__find(std::__unwrap_iter(__first), std::__unwrap_iter(__last), __value, __proj));
	}

	_LIBCPP_END_NAMESPACE_STD

	_LIBCPP_POP_MACROS

	#endif // _LIBCPP___ALGORITHM_FIND_H