text: // -*- C++ -*-
  //===----------------------------------------------------------------------===//
  //
  // Copyright (C) Intel Corporation
  //
  // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
  //
  // This file incorporates work covered by the following copyright and permission
  // notice:
  //
  // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
  // See https://llvm.org/LICENSE.txt for license information.
  //
  //===----------------------------------------------------------------------===//
  
  #ifndef _ONEDPL_ALGORITHM_IMPL_H
  #define _ONEDPL_ALGORITHM_IMPL_H
  
  #include <iterator>
  #include <type_traits>
  #include <functional>
  #include <algorithm>
  
  #include "algorithm_fwd.h"
  
  #include "execution_impl.h"
  #include "memory_impl.h"
  #include "parallel_backend_utils.h"
  #include "unseq_backend_simd.h"
  
  #include "parallel_backend.h"
  #include "parallel_impl.h"
  #include "iterator_impl.h"
  
  #if _ONEDPL_HETERO_BACKEND
  #    include "hetero/algorithm_impl_hetero.h" // for __pattern_fill_n, __pattern_generate_n
  #endif
  
  namespace oneapi
  {
  namespace dpl
  {
  namespace __internal
  {
  
  //------------------------------------------------------------------------
  // any_of
  //------------------------------------------------------------------------
  
  template <class _ForwardIterator, class _Pred>
  bool
  __brick_any_of(const _ForwardIterator __first, const _ForwardIterator __last, _Pred __pred,
                 /*__is_vector=*/::std::false_type) noexcept
  {
      return ::std::any_of(__first, __last, __pred);
  };
  
  template <class _ForwardIterator, class _Pred>
  bool
  __brick_any_of(const _ForwardIterator __first, const _ForwardIterator __last, _Pred __pred,
                 /*__is_vector=*/::std::true_type) noexcept
  {
      return __unseq_backend::__simd_or(__first, __last - __first, __pred);
  };
  
  template <class _ExecutionPolicy, class _ForwardIterator, class _Pred, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, bool>
  __pattern_any_of(_ExecutionPolicy&&, _ForwardIterator __first, _ForwardIterator __last, _Pred __pred,
                   _IsVector __is_vector, /*parallel=*/::std::false_type) noexcept
  {
      return __internal::__brick_any_of(__first, __last, __pred, __is_vector);
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator, class _Pred, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, bool>
  __pattern_any_of(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last, _Pred __pred,
                   _IsVector __is_vector, /*parallel=*/::std::true_type)
  {
      return __internal::__except_handler([&]() {
          return __internal::__parallel_or(::std::forward<_ExecutionPolicy>(__exec), __first, __last,
                                           [__pred, __is_vector](_ForwardIterator __i, _ForwardIterator __j) {
                                               return __internal::__brick_any_of(__i, __j, __pred, __is_vector);
                                           });
      });
  }
  
  // [alg.foreach]
  // for_each_n with no policy
  
  template <class _ForwardIterator, class _Size, class _Function>
  _ForwardIterator
  __for_each_n_it_serial(_ForwardIterator __first, _Size __n, _Function __f)
  {
      for (; __n > 0; ++__first, --__n)
          __f(__first);
      return __first;
  }
  
  //------------------------------------------------------------------------
  // walk1 (pseudo)
  //
  // walk1 evaluates f(x) for each dereferenced value x drawn from [first,last)
  //------------------------------------------------------------------------
  template <class _ForwardIterator, class _Function>
  void
  __brick_walk1(_ForwardIterator __first, _ForwardIterator __last, _Function __f, /*vector=*/::std::false_type) noexcept
  {
      ::std::for_each(__first, __last, __f);
  }
  
  template <class _RandomAccessIterator, class _Function>
  void
  __brick_walk1(_RandomAccessIterator __first, _RandomAccessIterator __last, _Function __f,
                /*vector=*/::std::true_type) noexcept
  {
      __unseq_backend::__simd_walk_1(__first, __last - __first, __f);
  }
  
  template <class _DifferenceType, class _Function>
  void
  __brick_walk1(_DifferenceType __n, _Function __f, ::std::false_type) noexcept
  {
      for (_DifferenceType __i = 0; __i < __n; ++__i)
          __f(__i);
  }
  
  template <class _DifferenceType, class _Function>
  void
  __brick_walk1(_DifferenceType __n, _Function __f, ::std::true_type) noexcept
  {
      // TODO: when using this overload the correctness of the vectorization depends on that functor is provided.
      // To avoid possible bugs we need to add a restriction on the functor so only the ones which would be
      // correctly vectorizes are used passed here. But for now, just re-direct to serial version.
      oneapi::dpl::__internal::__brick_walk1(__n, __f, ::std::false_type{});
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator, class _Function, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, void>
  __pattern_walk1(_ExecutionPolicy&&, _ForwardIterator __first, _ForwardIterator __last, _Function __f,
                  _IsVector __is_vector,
                  /*parallel=*/::std::false_type) noexcept
  {
      __internal::__brick_walk1(__first, __last, __f, __is_vector);
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator, class _Function, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy_conditional<
      _ExecutionPolicy, __is_random_access_iterator<_ForwardIterator>::value, void>
  __pattern_walk1(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last, _Function __f,
                  _IsVector __is_vector,
                  /*parallel=*/::std::true_type)
  {
      __internal::__except_handler([&]() {
          __par_backend::__parallel_for(::std::forward<_ExecutionPolicy>(__exec), __first, __last,
                                        [__f, __is_vector](_ForwardIterator __i, _ForwardIterator __j) {
                                            __internal::__brick_walk1(__i, __j, __f, __is_vector);
                                        });
      });
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator, class _Function, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy_conditional<
      _ExecutionPolicy, !__is_random_access_iterator<_ForwardIterator>::value, void>
  __pattern_walk1(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last, _Function __f, _IsVector,
                  /*parallel=*/::std::true_type)
  {
      typedef typename ::std::iterator_traits<_ForwardIterator>::reference _ReferenceType;
      auto __func = [&__f](_ReferenceType arg) { __f(arg); };
      __internal::__except_handler([&]() {
          __par_backend::__parallel_for_each(::std::forward<_ExecutionPolicy>(__exec), __first, __last, __func);
      });
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator, class _Brick>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, void>
  __pattern_walk_brick(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last, _Brick __brick,
                       /*parallel=*/::std::false_type) noexcept
  {
      const auto __is_vector = __internal::__is_vectorization_preferred<_ExecutionPolicy, _ForwardIterator>(__exec);
      __brick(__first, __last, __is_vector);
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator, class _Brick>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, void>
  __pattern_walk_brick(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last, _Brick __brick,
                       /*parallel=*/::std::true_type)
  {
      const auto __is_vector = __internal::__is_vectorization_preferred<_ExecutionPolicy, _ForwardIterator>(__exec);
      __internal::__except_handler([&]() {
          __par_backend::__parallel_for(
              ::std::forward<_ExecutionPolicy>(__exec), __first, __last,
              [__brick, __is_vector](_ForwardIterator __i, _ForwardIterator __j) { __brick(__i, __j, __is_vector); });
      });
  }
  
  //------------------------------------------------------------------------
  // walk1_n
  //------------------------------------------------------------------------
  template <class _ForwardIterator, class _Size, class _Function>
  _ForwardIterator
  __brick_walk1_n(_ForwardIterator __first, _Size __n, _Function __f, /*_IsVectorTag=*/::std::false_type)
  {
      return __internal::__for_each_n_it_serial(__first, __n,
                                                [&__f](_ForwardIterator __it) { __f(*__it); }); // calling serial version
  }
  
  template <class _RandomAccessIterator, class _DifferenceType, class _Function>
  _RandomAccessIterator
  __brick_walk1_n(_RandomAccessIterator __first, _DifferenceType __n, _Function __f,
                  /*vectorTag=*/::std::true_type) noexcept
  {
      return __unseq_backend::__simd_walk_1(__first, __n, __f);
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator, class _Size, class _Function, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _ForwardIterator>
  __pattern_walk1_n(_ExecutionPolicy&&, _ForwardIterator __first, _Size __n, _Function __f, _IsVector __is_vector,
                    /*is_parallel=*/::std::false_type) noexcept
  {
      return __internal::__brick_walk1_n(__first, __n, __f, __is_vector);
  }
  
  template <class _ExecutionPolicy, class _RandomAccessIterator, class _Size, class _Function, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _RandomAccessIterator>
  __pattern_walk1_n(_ExecutionPolicy&& __exec, _RandomAccessIterator __first, _Size __n, _Function __f,
                    _IsVector __is_vector,
                    /*is_parallel=*/::std::true_type)
  {
      oneapi::dpl::__internal::__pattern_walk1(::std::forward<_ExecutionPolicy>(__exec), __first, __first + __n, __f,
                                               __is_vector, ::std::true_type());
      return __first + __n;
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator, class _Size, class _Brick>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _ForwardIterator>
  __pattern_walk_brick_n(_ExecutionPolicy&& __exec, _ForwardIterator __first, _Size __n, _Brick __brick,
                         /*is_parallel=*/::std::false_type) noexcept
  {
      const auto __is_vector = __internal::__is_vectorization_preferred<_ExecutionPolicy, _ForwardIterator>(__exec);
      return __brick(__first, __n, __is_vector);
  }
  
  template <class _ExecutionPolicy, class _RandomAccessIterator, class _Size, class _Brick>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _RandomAccessIterator>
  __pattern_walk_brick_n(_ExecutionPolicy&& __exec, _RandomAccessIterator __first, _Size __n, _Brick __brick,
                         /*is_parallel=*/::std::true_type)
  {
      const auto __is_vector = __internal::__is_vectorization_preferred<_ExecutionPolicy, _RandomAccessIterator>(__exec);
      return __internal::__except_handler([&]() {
          __par_backend::__parallel_for(::std::forward<_ExecutionPolicy>(__exec), __first, __first + __n,
                                        [__brick, __is_vector](_RandomAccessIterator __i, _RandomAccessIterator __j) {
                                            __brick(__i, __j - __i, __is_vector);
                                        });
          return __first + __n;
      });
  }
  
  //------------------------------------------------------------------------
  // walk2 (pseudo)
  //
  // walk2 evaluates f(x,y) for deferenced values (x,y) drawn from [first1,last1) and [first2,...)
  //------------------------------------------------------------------------
  template <class _ForwardIterator1, class _ForwardIterator2, class _Function>
  _ForwardIterator2
  __brick_walk2(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2, _Function __f,
                /*vector=*/::std::false_type) noexcept
  {
      for (; __first1 != __last1; ++__first1, ++__first2)
          __f(*__first1, *__first2);
      return __first2;
  }
  
  template <class _ForwardIterator1, class _ForwardIterator2, class _Function>
  _ForwardIterator2
  __brick_walk2(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2, _Function __f,
                /*vector=*/::std::true_type) noexcept
  {
      return __unseq_backend::__simd_walk_2(__first1, __last1 - __first1, __first2, __f);
  }
  
  template <class _ForwardIterator1, class _Size, class _ForwardIterator2, class _Function>
  _ForwardIterator2
  __brick_walk2_n(_ForwardIterator1 __first1, _Size __n, _ForwardIterator2 __first2, _Function __f,
                  /*vector=*/::std::false_type) noexcept
  {
      for (; __n > 0; --__n, ++__first1, ++__first2)
          __f(*__first1, *__first2);
      return __first2;
  }
  
  template <class _ForwardIterator1, class _Size, class _ForwardIterator2, class _Function>
  _ForwardIterator2
  __brick_walk2_n(_ForwardIterator1 __first1, _Size __n, _ForwardIterator2 __first2, _Function __f,
                  /*vector=*/::std::true_type) noexcept
  {
      return __unseq_backend::__simd_walk_2(__first1, __n, __first2, __f);
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _Function, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _ForwardIterator2>
  __pattern_walk2(_ExecutionPolicy&&, _ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2,
                  _Function __f, _IsVector __is_vector, /*parallel=*/::std::false_type) noexcept
  {
      return __internal::__brick_walk2(__first1, __last1, __first2, __f, __is_vector);
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _Function, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy_conditional<
      _ExecutionPolicy, __is_random_access_iterator<_ForwardIterator1, _ForwardIterator2>::value, _ForwardIterator2>
  __pattern_walk2(_ExecutionPolicy&& __exec, _ForwardIterator1 __first1, _ForwardIterator1 __last1,
                  _ForwardIterator2 __first2, _Function __f, _IsVector __is_vector, /*parallel=*/::std::true_type)
  {
      return __internal::__except_handler([&]() {
          __par_backend::__parallel_for(
              ::std::forward<_ExecutionPolicy>(__exec), __first1, __last1,
              [__f, __first1, __first2, __is_vector](_ForwardIterator1 __i, _ForwardIterator1 __j) {
                  __internal::__brick_walk2(__i, __j, __first2 + (__i - __first1), __f, __is_vector);
              });
          return __first2 + (__last1 - __first1);
      });
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _Function, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy_conditional<
      _ExecutionPolicy, !__is_random_access_iterator<_ForwardIterator1, _ForwardIterator2>::value, _ForwardIterator2>
  __pattern_walk2(_ExecutionPolicy&& __exec, _ForwardIterator1 __first1, _ForwardIterator1 __last1,
                  _ForwardIterator2 __first2, _Function __f, _IsVector, /*parallel=*/::std::true_type)
  {
      return __internal::__except_handler([&]() {
          using _iterator_tuple = zip_forward_iterator<_ForwardIterator1, _ForwardIterator2>;
          auto __begin = _iterator_tuple(__first1, __first2);
          auto __end = _iterator_tuple(__last1, /*dummy parameter*/ _ForwardIterator2());
  
          typedef typename ::std::iterator_traits<_ForwardIterator1>::reference _ReferenceType1;
          typedef typename ::std::iterator_traits<_ForwardIterator2>::reference _ReferenceType2;
  
          __par_backend::__parallel_for_each(::std::forward<_ExecutionPolicy>(__exec), __begin, __end,
                                             [&__f](const ::std::tuple<_ReferenceType1, _ReferenceType2>& __val) {
                                                 __f(::std::get<0>(__val), ::std::get<1>(__val));
                                             });
  
          //TODO: parallel_for_each does not allow to return correct iterator value according to the ::std::transform
          // implementation. Therefore, iterator value is calculated separately.
          for (; __begin != __end; ++__begin)
              ;
          return ::std::get<1>(__begin.base());
      });
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator1, class _Size, class _ForwardIterator2, class _Function,
            class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _ForwardIterator2>
  __pattern_walk2_n(_ExecutionPolicy&&, _ForwardIterator1 __first1, _Size __n, _ForwardIterator2 __first2, _Function __f,
                    _IsVector __is_vector, /*parallel=*/::std::false_type) noexcept
  {
      return __internal::__brick_walk2_n(__first1, __n, __first2, __f, __is_vector);
  }
  
  template <class _ExecutionPolicy, class _RandomAccessIterator1, class _Size, class _RandomAccessIterator2,
            class _Function, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _RandomAccessIterator2>
  __pattern_walk2_n(_ExecutionPolicy&& __exec, _RandomAccessIterator1 __first1, _Size __n,
                    _RandomAccessIterator2 __first2, _Function __f, _IsVector __is_vector, /*parallel=*/::std::true_type)
  {
      return __internal::__pattern_walk2(::std::forward<_ExecutionPolicy>(__exec), __first1, __first1 + __n, __first2,
                                         __f, __is_vector, ::std::true_type());
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _Brick>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _ForwardIterator2>
  __pattern_walk2_brick(_ExecutionPolicy&& __exec, _ForwardIterator1 __first1, _ForwardIterator1 __last1,
                        _ForwardIterator2 __first2, _Brick __brick, /*parallel=*/::std::false_type) noexcept
  {
      const auto __is_vector =
          __internal::__is_vectorization_preferred<_ExecutionPolicy, _ForwardIterator1, _ForwardIterator2>(__exec);
      return __brick(__first1, __last1, __first2, __is_vector);
  }
  
  template <class _ExecutionPolicy, class _RandomAccessIterator1, class _RandomAccessIterator2, class _Brick>
  oneapi::dpl::__internal::__enable_if_host_execution_policy_conditional<
      _ExecutionPolicy, __is_random_access_iterator<_RandomAccessIterator1, _RandomAccessIterator2>::value,
      _RandomAccessIterator2>
  __pattern_walk2_brick(_ExecutionPolicy&& __exec, _RandomAccessIterator1 __first1, _RandomAccessIterator1 __last1,
                        _RandomAccessIterator2 __first2, _Brick __brick, /*parallel=*/::std::true_type)
  {
      const auto __is_vector =
          __internal::__is_vectorization_preferred<_ExecutionPolicy, _RandomAccessIterator1, _RandomAccessIterator2>(
              __exec);
  
      return __except_handler([&]() {
          __par_backend::__parallel_for(
              ::std::forward<_ExecutionPolicy>(__exec), __first1, __last1,
              [&__is_vector, __first1, __first2, __brick](_RandomAccessIterator1 __i, _RandomAccessIterator1 __j) {
                  __brick(__i, __j, __first2 + (__i - __first1), __is_vector);
              });
          return __first2 + (__last1 - __first1);
      });
  }
  
  //TODO: it postponed till adding more or less effective parallel implementation
  template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _Brick>
  oneapi::dpl::__internal::__enable_if_host_execution_policy_conditional<
      _ExecutionPolicy, !__is_random_access_iterator<_ForwardIterator1, _ForwardIterator2>::value, _ForwardIterator2>
  __pattern_walk2_brick(_ExecutionPolicy&& __exec, _ForwardIterator1 __first1, _ForwardIterator1 __last1,
                        _ForwardIterator2 __first2, _Brick __brick, /*parallel=*/::std::true_type)
  {
      using _iterator_tuple = zip_forward_iterator<_ForwardIterator1, _ForwardIterator2>;
      auto __begin = _iterator_tuple(__first1, __first2);
      auto __end = _iterator_tuple(__last1, /*dummy parameter*/ _ForwardIterator2());
  
      typedef typename ::std::iterator_traits<_ForwardIterator1>::reference _ReferenceType1;
      typedef typename ::std::iterator_traits<_ForwardIterator2>::reference _ReferenceType2;
  
      return __except_handler([&]() {
          __par_backend::__parallel_for_each(::std::forward<_ExecutionPolicy>(__exec), __begin, __end,
                                             [__brick](const ::std::tuple<_ReferenceType1, _ReferenceType2>& __val) {
                                                 __brick(::std::get<0>(__val),
                                                         ::std::forward<_ReferenceType2>(::std::get<1>(__val)));
                                             });
  
          //TODO: parallel_for_each does not allow to return correct iterator value according to the ::std::transform
          // implementation. Therefore, iterator value is calculated separately.
          for (; __begin != __end; ++__begin)
              ;
          return ::std::get<1>(__begin.base());
      });
  }
  
  template <class _ExecutionPolicy, class _RandomAccessIterator1, class _Size, class _RandomAccessIterator2, class _Brick>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _RandomAccessIterator2>
  __pattern_walk2_brick_n(_ExecutionPolicy&& __exec, _RandomAccessIterator1 __first1, _Size __n,
                          _RandomAccessIterator2 __first2, _Brick __brick, /*parallel=*/::std::true_type)
  {
      const auto __is_vector =
          __internal::__is_vectorization_preferred<_ExecutionPolicy, _RandomAccessIterator1, _RandomAccessIterator2>(
              __exec);
  
      return __except_handler([&]() {
          __par_backend::__parallel_for(
              ::std::forward<_ExecutionPolicy>(__exec), __first1, __first1 + __n,
              [&__is_vector, __first1, __first2, __brick](_RandomAccessIterator1 __i, _RandomAccessIterator1 __j) {
                  __brick(__i, __j - __i, __first2 + (__i - __first1), __is_vector);
              });
          return __first2 + __n;
      });
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator1, class _Size, class _ForwardIterator2, class _Brick>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _ForwardIterator2>
  __pattern_walk2_brick_n(_ExecutionPolicy&& __exec, _ForwardIterator1 __first1, _Size __n, _ForwardIterator2 __first2,
                          _Brick __brick, /*parallel=*/::std::false_type) noexcept
  {
      const auto __is_vector =
          __internal::__is_vectorization_preferred<_ExecutionPolicy, _ForwardIterator1, _ForwardIterator2>(__exec);
      return __brick(__first1, __n, __first2, __is_vector);
  }
  
  //------------------------------------------------------------------------
  // walk3 (pseudo)
  //
  // walk3 evaluates f(x,y,z) for (x,y,z) drawn from [first1,last1), [first2,...), [first3,...)
  //------------------------------------------------------------------------
  template <class _ForwardIterator1, class _ForwardIterator2, class _ForwardIterator3, class _Function>
  _ForwardIterator3
  __brick_walk3(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2,
                _ForwardIterator3 __first3, _Function __f, /*vector=*/::std::false_type) noexcept
  {
      for (; __first1 != __last1; ++__first1, ++__first2, ++__first3)
          __f(*__first1, *__first2, *__first3);
      return __first3;
  }
  
  template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _RandomAccessIterator3, class _Function>
  _RandomAccessIterator3
  __brick_walk3(_RandomAccessIterator1 __first1, _RandomAccessIterator1 __last1, _RandomAccessIterator2 __first2,
                _RandomAccessIterator3 __first3, _Function __f, /*vector=*/::std::true_type) noexcept
  {
      return __unseq_backend::__simd_walk_3(__first1, __last1 - __first1, __first2, __first3, __f);
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _ForwardIterator3,
            class _Function, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _ForwardIterator3>
  __pattern_walk3(_ExecutionPolicy&&, _ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2,
                  _ForwardIterator3 __first3, _Function __f, _IsVector __is_vector,
                  /*parallel=*/::std::false_type) noexcept
  {
      return __internal::__brick_walk3(__first1, __last1, __first2, __first3, __f, __is_vector);
  }
  
  template <class _ExecutionPolicy, class _RandomAccessIterator1, class _RandomAccessIterator2,
            class _RandomAccessIterator3, class _Function, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy_conditional<
      _ExecutionPolicy,
      __is_random_access_iterator<_RandomAccessIterator1, _RandomAccessIterator2, _RandomAccessIterator3>::value,
      _RandomAccessIterator3>
  __pattern_walk3(_ExecutionPolicy&& __exec, _RandomAccessIterator1 __first1, _RandomAccessIterator1 __last1,
                  _RandomAccessIterator2 __first2, _RandomAccessIterator3 __first3, _Function __f, _IsVector __is_vector,
                  /*parallel=*/::std::true_type)
  {
      return __internal::__except_handler([&]() {
          __par_backend::__parallel_for(
              ::std::forward<_ExecutionPolicy>(__exec), __first1, __last1,
              [__f, __first1, __first2, __first3, __is_vector](_RandomAccessIterator1 __i, _RandomAccessIterator1 __j) {
                  __internal::__brick_walk3(__i, __j, __first2 + (__i - __first1), __first3 + (__i - __first1), __f,
                                            __is_vector);
              });
          return __first3 + (__last1 - __first1);
      });
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _ForwardIterator3,
            class _Function, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy_conditional<
      _ExecutionPolicy, !__is_random_access_iterator<_ForwardIterator1, _ForwardIterator2, _ForwardIterator3>::value,
      _ForwardIterator3>
  __pattern_walk3(_ExecutionPolicy&& __exec, _ForwardIterator1 __first1, _ForwardIterator1 __last1,
                  _ForwardIterator2 __first2, _ForwardIterator3 __first3, _Function __f, _IsVector,
                  /*parallel=*/::std::true_type)
  {
      return __internal::__except_handler([&]() {
          using _iterator_tuple = zip_forward_iterator<_ForwardIterator1, _ForwardIterator2, _ForwardIterator3>;
          auto __begin = _iterator_tuple(__first1, __first2, __first3);
          auto __end = _iterator_tuple(__last1, /*dummy parameter*/ _ForwardIterator2(),
                                       /*dummy parameter*/ _ForwardIterator3());
  
          typedef typename ::std::iterator_traits<_ForwardIterator1>::reference _ReferenceType1;
          typedef typename ::std::iterator_traits<_ForwardIterator2>::reference _ReferenceType2;
          typedef typename ::std::iterator_traits<_ForwardIterator3>::reference _ReferenceType3;
  
          __par_backend::__parallel_for_each(
              ::std::forward<_ExecutionPolicy>(__exec), __begin, __end,
              [&](const ::std::tuple<_ReferenceType1, _ReferenceType2, _ReferenceType3>& __val) {
                  __f(::std::get<0>(__val), ::std::get<1>(__val), ::std::get<2>(__val));
              });
  
          //TODO: parallel_for_each does not allow to return correct iterator value according to the ::std::transform
          // implementation. Therefore, iterator value is calculated separately.
          for (; __begin != __end; ++__begin)
              ;
          return ::std::get<2>(__begin.base());
      });
  }
  
  //------------------------------------------------------------------------
  // equal
  //------------------------------------------------------------------------
  
  template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
  bool
  __brick_equal(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2,
                _ForwardIterator2 __last2, _BinaryPredicate __p, /* IsVector = */ ::std::false_type) noexcept
  {
  #if (_PSTL_CPP14_2RANGE_MISMATCH_EQUAL_PRESENT || _ONEDPL_CPP14_2RANGE_MISMATCH_EQUAL_PRESENT)
      return ::std::equal(__first1, __last1, __first2, __last2, __p);
  #else
      return __invoke_if_else(typename __is_random_access_iterator<_ForwardIterator1, _ForwardIterator2>::type(),
                              [&]() {
                                  if (::std::distance(__first1, __last1) != ::std::distance(__first2, __last2))
                                      return false;
                                  return ::std::equal(__first1, __last1, __first2, __p);
                              },
                              [&]() {
                                  for (; __first1 != __last1 && __first2 != __last2; __first1++, __first2++)
                                      if (!__p(*__first1, *__first2))
                                          return false;
  
                                  return __first1 == __last1 && __first2 == __last2;
                              });
  #endif
  }
  
  template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _BinaryPredicate>
  bool
  __brick_equal(_RandomAccessIterator1 __first1, _RandomAccessIterator1 __last1, _RandomAccessIterator2 __first2,
                _RandomAccessIterator2 __last2, _BinaryPredicate __p, /* is_vector = */ ::std::true_type) noexcept
  {
      if (__last1 - __first1 != __last2 - __first2)
          return false;
  
      return __unseq_backend::__simd_first(__first1, __last1 - __first1, __first2, __not_pred<_BinaryPredicate&>(__p))
                 .first == __last1;
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate,
            class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, bool>
  __pattern_equal(_ExecutionPolicy&&, _ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2,
                  _ForwardIterator2 __last2, _BinaryPredicate __p, _IsVector __is_vector, /* is_parallel = */
                  ::std::false_type) noexcept
  {
      return __internal::__brick_equal(__first1, __last1, __first2, __last2, __p, __is_vector);
  }
  
  template <class _ExecutionPolicy, class _RandomAccessIterator1, class _RandomAccessIterator2, class _BinaryPredicate,
            class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, bool>
  __pattern_equal(_ExecutionPolicy&& __exec, _RandomAccessIterator1 __first1, _RandomAccessIterator1 __last1,
                  _RandomAccessIterator2 __first2, _RandomAccessIterator2 __last2, _BinaryPredicate __p,
                  _IsVector __is_vector, /*is_parallel=*/::std::true_type)
  {
      if (__last1 - __first1 != __last2 - __first2)
          return false;
  
      return __internal::__except_handler([&]() {
          return !__internal::__parallel_or(
              ::std::forward<_ExecutionPolicy>(__exec), __first1, __last1,
              [__first1, __first2, __p, __is_vector](_RandomAccessIterator1 __i, _RandomAccessIterator1 __j) {
                  return !__brick_equal(__i, __j, __first2 + (__i - __first1), __first2 + (__j - __first1), __p,
                                        __is_vector);
              });
      });
  }
  
  //------------------------------------------------------------------------
  // equal version for sequences with equal length
  //------------------------------------------------------------------------
  
  template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
  bool
  __brick_equal(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2, _BinaryPredicate __p,
                /* IsVector = */ ::std::false_type) noexcept
  {
      return ::std::equal(__first1, __last1, __first2, __p);
  }
  
  template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _BinaryPredicate>
  bool
  __brick_equal(_RandomAccessIterator1 __first1, _RandomAccessIterator1 __last1, _RandomAccessIterator2 __first2,
                _BinaryPredicate __p, /* is_vector = */ ::std::true_type) noexcept
  {
      return __unseq_backend::__simd_first(__first1, __last1 - __first1, __first2, __not_pred<_BinaryPredicate&>(__p))
                 .first == __last1;
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate,
            class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, bool>
  __pattern_equal(_ExecutionPolicy&&, _ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2,
                  _BinaryPredicate __p, _IsVector __is_vector, /* is_parallel = */ ::std::false_type) noexcept
  {
      return __internal::__brick_equal(__first1, __last1, __first2, __p, __is_vector);
  }
  
  template <class _ExecutionPolicy, class _RandomAccessIterator1, class _RandomAccessIterator2, class _BinaryPredicate,
            class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, bool>
  __pattern_equal(_ExecutionPolicy&& __exec, _RandomAccessIterator1 __first1, _RandomAccessIterator1 __last1,
                  _RandomAccessIterator2 __first2, _BinaryPredicate __p, _IsVector __is_vector,
                  /*is_parallel=*/::std::true_type)
  {
      return __internal::__except_handler([&]() {
          return !__internal::__parallel_or(
              ::std::forward<_ExecutionPolicy>(__exec), __first1, __last1,
              [__first1, __first2, __p, __is_vector](_RandomAccessIterator1 __i, _RandomAccessIterator1 __j) {
                  return !__internal::__brick_equal(__i, __j, __first2 + (__i - __first1), __p, __is_vector);
              });
      });
  }
  
  //------------------------------------------------------------------------
  // find_if
  //------------------------------------------------------------------------
  template <class _ForwardIterator, class _Predicate>
  _ForwardIterator
  __brick_find_if(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred,
                  /*is_vector=*/::std::false_type) noexcept
  {
      return ::std::find_if(__first, __last, __pred);
  }
  
  template <class _RandomAccessIterator, class _Predicate>
  _RandomAccessIterator
  __brick_find_if(_RandomAccessIterator __first, _RandomAccessIterator __last, _Predicate __pred,
                  /*is_vector=*/::std::true_type) noexcept
  {
      typedef typename ::std::iterator_traits<_RandomAccessIterator>::difference_type _SizeType;
      return __unseq_backend::__simd_first(
          __first, _SizeType(0), __last - __first,
          [&__pred](_RandomAccessIterator __it, _SizeType __i) { return __pred(__it[__i]); });
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator, class _Predicate, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _ForwardIterator>
  __pattern_find_if(_ExecutionPolicy&&, _ForwardIterator __first, _ForwardIterator __last, _Predicate __pred,
                    _IsVector __is_vector,
                    /*is_parallel=*/::std::false_type) noexcept
  {
      return __internal::__brick_find_if(__first, __last, __pred, __is_vector);
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator, class _Predicate, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _ForwardIterator>
  __pattern_find_if(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last, _Predicate __pred,
                    _IsVector __is_vector,
                    /*is_parallel=*/::std::true_type)
  {
      return __except_handler([&]() {
          return __parallel_find(::std::forward<_ExecutionPolicy>(__exec), __first, __last,
                                 [__pred, __is_vector](_ForwardIterator __i, _ForwardIterator __j) {
                                     return __brick_find_if(__i, __j, __pred, __is_vector);
                                 },
                                 ::std::true_type{});
      });
  }
  
  //------------------------------------------------------------------------
  // find_end
  //------------------------------------------------------------------------
  
  // find the first occurrence of the subsequence [s_first, s_last)
  //   or the  last occurrence of the subsequence in the range [first, last)
  // b_first determines what occurrence we want to find (first or last)
  template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _BinaryPredicate, class _IsVector>
  _RandomAccessIterator1
  __find_subrange(_RandomAccessIterator1 __first, _RandomAccessIterator1 __last, _RandomAccessIterator1 __global_last,
                  _RandomAccessIterator2 __s_first, _RandomAccessIterator2 __s_last, _BinaryPredicate __pred,
                  bool __b_first, _IsVector __is_vector) noexcept
  {
      typedef typename ::std::iterator_traits<_RandomAccessIterator2>::value_type _ValueType;
      auto __n2 = __s_last - __s_first;
      if (__n2 < 1)
      {
          return __b_first ? __first : __last;
      }
  
      auto __n1 = __global_last - __first;
      if (__n1 < __n2)
      {
          return __last;
      }
  
      auto __cur = __last;
      while (__first != __last && (__global_last - __first >= __n2))
      {
          // find position of *s_first in [first, last) (it can be start of subsequence)
          __first = __internal::__brick_find_if(
              __first, __last, __equal_value_by_pred<_ValueType, _BinaryPredicate&>(*__s_first, __pred), __is_vector);
  
          // if position that was found previously is the start of subsequence
          // then we can exit the loop (b_first == true) or keep the position
          // (b_first == false)
          if (__first != __last && (__global_last - __first >= __n2) &&
              __internal::__brick_equal(__s_first + 1, __s_last, __first + 1, __pred, __is_vector))
          {
              if (__b_first)
              {
                  return __first;
              }
              else
              {
                  __cur = __first;
              }
          }
          else if (__first == __last)
          {
              break;
          }
          else
          {
          }
  
          // in case of b_first == false we try to find new start position
          // for the next subsequence
          ++__first;
      }
      return __cur;
  }
  
  template <class _RandomAccessIterator, class _Size, class _Tp, class _BinaryPredicate, class _IsVector>
  _RandomAccessIterator
  __find_subrange(_RandomAccessIterator __first, _RandomAccessIterator __last, _RandomAccessIterator __global_last,
                  _Size __count, const _Tp& __value, _BinaryPredicate __pred, _IsVector __is_vector) noexcept
  {
      if (__count < 1)
      {
          return __first;
      }
  
      if (__global_last - __first < __count)
      {
          return __last;
      }
  
      auto __unary_pred = __equal_value_by_pred<_Tp, _BinaryPredicate&>(__value, __pred);
      while (__first != __last && (__global_last - __first >= __count))
      {
          __first = __internal::__brick_find_if(__first, __last, __unary_pred, __is_vector);
  
          // check that all of elements in [first+1, first+count) equal to value
          if (__first != __last && (__global_last - __first >= __count) &&
              !__internal::__brick_any_of(__first + 1, __first + __count,
                                          __not_pred<decltype(__unary_pred)&>(__unary_pred), __is_vector))
          {
              return __first;
          }
          else if (__first == __last)
          {
              break;
          }
          else
          {
              ++__first;
          }
      }
      return __last;
  }
  
  template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
  _ForwardIterator1
  __brick_find_end(_ForwardIterator1 __first, _ForwardIterator1 __last, _ForwardIterator2 __s_first,
                   _ForwardIterator2 __s_last, _BinaryPredicate __pred, /*__is_vector=*/::std::false_type) noexcept
  {
      return ::std::find_end(__first, __last, __s_first, __s_last, __pred);
  }
  
  template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
  _ForwardIterator1
  __brick_find_end(_ForwardIterator1 __first, _ForwardIterator1 __last, _ForwardIterator2 __s_first,
                   _ForwardIterator2 __s_last, _BinaryPredicate __pred, /*__is_vector=*/::std::true_type) noexcept
  {
      return __find_subrange(__first, __last, __last, __s_first, __s_last, __pred, false, ::std::true_type());
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate,
            class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _ForwardIterator1>
  __pattern_find_end(_ExecutionPolicy&&, _ForwardIterator1 __first, _ForwardIterator1 __last, _ForwardIterator2 __s_first,
                     _ForwardIterator2 __s_last, _BinaryPredicate __pred, _IsVector __is_vector,
                     /*is_parallel=*/::std::false_type) noexcept
  {
      return __internal::__brick_find_end(__first, __last, __s_first, __s_last, __pred, __is_vector);
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate,
            class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _ForwardIterator1>
  __pattern_find_end(_ExecutionPolicy&& __exec, _ForwardIterator1 __first, _ForwardIterator1 __last,
                     _ForwardIterator2 __s_first, _ForwardIterator2 __s_last, _BinaryPredicate __pred,
                     _IsVector __is_vector, /*is_parallel=*/::std::true_type)
  {
      if (__last - __first == __s_last - __s_first)
      {
          const bool __res = __internal::__pattern_equal(::std::forward<_ExecutionPolicy>(__exec), __first, __last,
                                                         __s_first, __pred, __is_vector, ::std::true_type());
          return __res ? __first : __last;
      }
      else
      {
          return __internal::__except_handler([&]() {
              return __internal::__parallel_find(
                  ::std::forward<_ExecutionPolicy>(__exec), __first, __last,
                  [__last, __s_first, __s_last, __pred, __is_vector](_ForwardIterator1 __i, _ForwardIterator1 __j) {
                      return __internal::__find_subrange(__i, __j, __last, __s_first, __s_last, __pred, false,
                                                         __is_vector);
                  },
                  ::std::false_type{});
          });
      }
  }
  
  //------------------------------------------------------------------------
  // find_first_of
  //------------------------------------------------------------------------
  template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
  _ForwardIterator1
  __brick_find_first_of(_ForwardIterator1 __first, _ForwardIterator1 __last, _ForwardIterator2 __s_first,
                        _ForwardIterator2 __s_last, _BinaryPredicate __pred, /*__is_vector=*/::std::false_type) noexcept
  {
      return ::std::find_first_of(__first, __last, __s_first, __s_last, __pred);
  }
  
  template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
  _ForwardIterator1
  __brick_find_first_of(_ForwardIterator1 __first, _ForwardIterator1 __last, _ForwardIterator2 __s_first,
                        _ForwardIterator2 __s_last, _BinaryPredicate __pred, /*__is_vector=*/::std::true_type) noexcept
  {
      return __unseq_backend::__simd_find_first_of(__first, __last, __s_first, __s_last, __pred);
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate,
            class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _ForwardIterator1>
  __pattern_find_first_of(_ExecutionPolicy&&, _ForwardIterator1 __first, _ForwardIterator1 __last,
                          _ForwardIterator2 __s_first, _ForwardIterator2 __s_last, _BinaryPredicate __pred,
                          _IsVector __is_vector, /*is_parallel=*/::std::false_type) noexcept
  {
      return __internal::__brick_find_first_of(__first, __last, __s_first, __s_last, __pred, __is_vector);
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate,
            class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _ForwardIterator1>
  __pattern_find_first_of(_ExecutionPolicy&& __exec, _ForwardIterator1 __first, _ForwardIterator1 __last,
                          _ForwardIterator2 __s_first, _ForwardIterator2 __s_last, _BinaryPredicate __pred,
                          _IsVector __is_vector, /*is_parallel=*/::std::true_type)
  {
      return __internal::__except_handler([&]() {
          return __internal::__parallel_find(
              ::std::forward<_ExecutionPolicy>(__exec), __first, __last,
              [__s_first, __s_last, &__pred, __is_vector](_ForwardIterator1 __i, _ForwardIterator1 __j) {
                  return __internal::__brick_find_first_of(__i, __j, __s_first, __s_last, __pred, __is_vector);
              },
              ::std::true_type{});
      });
  }
  
  //------------------------------------------------------------------------
  // search
  //------------------------------------------------------------------------
  template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
  _ForwardIterator1
  __brick_search(_ForwardIterator1 __first, _ForwardIterator1 __last, _ForwardIterator2 __s_first,
                 _ForwardIterator2 __s_last, _BinaryPredicate __pred, /*vector=*/::std::false_type) noexcept
  {
      return ::std::search(__first, __last, __s_first, __s_last, __pred);
  }
  
  template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
  _ForwardIterator1
  __brick_search(_ForwardIterator1 __first, _ForwardIterator1 __last, _ForwardIterator2 __s_first,
                 _ForwardIterator2 __s_last, _BinaryPredicate __pred, /*vector=*/::std::true_type) noexcept
  {
      return __internal::__find_subrange(__first, __last, __last, __s_first, __s_last, __pred, true, ::std::true_type());
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate,
            class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _ForwardIterator1>
  __pattern_search(_ExecutionPolicy&&, _ForwardIterator1 __first, _ForwardIterator1 __last, _ForwardIterator2 __s_first,
                   _ForwardIterator2 __s_last, _BinaryPredicate __pred, _IsVector __is_vector,
                   /*is_parallel=*/::std::false_type) noexcept
  {
      return __internal::__brick_search(__first, __last, __s_first, __s_last, __pred, __is_vector);
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate,
            class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _ForwardIterator1>
  __pattern_search(_ExecutionPolicy&& __exec, _ForwardIterator1 __first, _ForwardIterator1 __last,
                   _ForwardIterator2 __s_first, _ForwardIterator2 __s_last, _BinaryPredicate __pred,
                   _IsVector __is_vector,
                   /*is_parallel=*/::std::true_type)
  {
      if (__last - __first == __s_last - __s_first)
      {
          const bool __res = __internal::__pattern_equal(::std::forward<_ExecutionPolicy>(__exec), __first, __last,
                                                         __s_first, __pred, __is_vector, ::std::true_type());
          return __res ? __first : __last;
      }
      else
      {
          return __internal::__except_handler([&]() {
              return __internal::__parallel_find(
                  ::std::forward<_ExecutionPolicy>(__exec), __first, __last,
                  [__last, __s_first, __s_last, __pred, __is_vector](_ForwardIterator1 __i, _ForwardIterator1 __j) {
                      return __internal::__find_subrange(__i, __j, __last, __s_first, __s_last, __pred, true,
                                                         __is_vector);
                  },
                  ::std::true_type{});
          });
      }
  }
  
  //------------------------------------------------------------------------
  // search_n
  //------------------------------------------------------------------------
  template <class _ForwardIterator, class _Size, class _Tp, class _BinaryPredicate>
  _ForwardIterator
  __brick_search_n(_ForwardIterator __first, _ForwardIterator __last, _Size __count, const _Tp& __value,
                   _BinaryPredicate __pred, /*vector=*/::std::false_type) noexcept
  {
      return ::std::search_n(__first, __last, __count, __value, __pred);
  }
  
  template <class _ForwardIterator, class _Size, class _Tp, class _BinaryPredicate>
  _ForwardIterator
  __brick_search_n(_ForwardIterator __first, _ForwardIterator __last, _Size __count, const _Tp& __value,
                   _BinaryPredicate __pred, /*vector=*/::std::true_type) noexcept
  {
      return __internal::__find_subrange(__first, __last, __last, __count, __value, __pred, ::std::true_type());
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator, class _Size, class _Tp, class _BinaryPredicate,
            class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _ForwardIterator>
  __pattern_search_n(_ExecutionPolicy&&, _ForwardIterator __first, _ForwardIterator __last, _Size __count,
                     const _Tp& __value, _BinaryPredicate __pred, _IsVector __is_vector,
                     /*is_parallel=*/::std::false_type) noexcept
  {
      return __internal::__brick_search_n(__first, __last, __count, __value, __pred, __is_vector);
  }
  
  template <class _ExecutionPolicy, class _RandomAccessIterator, class _Size, class _Tp, class _BinaryPredicate,
            class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _RandomAccessIterator>
  __pattern_search_n(_ExecutionPolicy&& __exec, _RandomAccessIterator __first, _RandomAccessIterator __last,
                     _Size __count, const _Tp& __value, _BinaryPredicate __pred, _IsVector __is_vector,
                     /*is_parallel=*/::std::true_type)
  {
      if (__last - __first == __count)
      {
          const bool __result =
              !__pattern_any_of(::std::forward<_ExecutionPolicy>(__exec), __first, __last,
                                [&__value, &__pred](const _Tp& __val) { return !__pred(__val, __value); }, __is_vector,
                                /*is_parallel*/ ::std::true_type());
          return __result ? __first : __last;
      }
      else
      {
          return __internal::__except_handler([&__exec, __first, __last, __count, &__value, __pred, __is_vector]() {
              return __internal::__parallel_find(
                  ::std::forward<_ExecutionPolicy>(__exec), __first, __last,
                  [__last, __count, &__value, __pred, __is_vector](_RandomAccessIterator __i, _RandomAccessIterator __j) {
                      return __internal::__find_subrange(__i, __j, __last, __count, __value, __pred, __is_vector);
                  },
                  ::std::true_type{});
          });
      }
  }
  
  //------------------------------------------------------------------------
  // copy_n
  //------------------------------------------------------------------------
  // It might be possible to share more between copy and copy_n, but it's not
  // clear that doing so is worth the trouble and extra layers of call chain.
  // Sometimes a little duplication for sake of regularity is better than the alternative.
  
  template <typename _ExecutionPolicy>
  struct __brick_copy_n<_ExecutionPolicy,
                        oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, void>>
  {
      template <typename _Iterator, typename _Size, typename _OutputIterator>
      _OutputIterator
      operator()(_Iterator __first, _Size __n, _OutputIterator __result, /*vec*/ ::std::true_type) const
      {
          return __unseq_backend::__simd_assign(
              __first, __n, __result, [](_Iterator __first, _OutputIterator __result) { *__result = *__first; });
      }
  
      template <typename _Iterator, typename _Size, typename _OutputIterator>
      _OutputIterator
      operator()(_Iterator __first, _Size __n, _OutputIterator __result, /*vec*/ ::std::false_type) const
      {
          return ::std::copy_n(__first, __n, __result);
      }
  };
  
  //------------------------------------------------------------------------
  // copy
  //------------------------------------------------------------------------
  
  template <typename _ExecutionPolicy>
  struct __brick_copy<_ExecutionPolicy,
                      oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, void>>
  {
  
      template <typename _Iterator, typename _OutputIterator>
      _OutputIterator
      operator()(_Iterator __first, _Iterator __last, _OutputIterator __result, /*vec*/ ::std::true_type) const
      {
          return __unseq_backend::__simd_assign(
              __first, __last - __first, __result,
              [](_Iterator __first, _OutputIterator __result) { *__result = *__first; });
      }
  
      template <typename _Iterator, typename _OutputIterator>
      _OutputIterator
      operator()(_Iterator __first, _Iterator __last, _OutputIterator __result, /*vec*/ ::std::false_type) const
      {
          return ::std::copy(__first, __last, __result);
      }
  
      template <typename _ReferenceType1, typename _ReferenceType2>
      void
      operator()(_ReferenceType1 __val, _ReferenceType2&& __result) const
      {
          __result = __val;
      }
  };
  
  //------------------------------------------------------------------------
  // move
  //------------------------------------------------------------------------
  
  template <typename _ExecutionPolicy>
  struct __brick_move<_ExecutionPolicy,
                      oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, void>>
  {
  
      template <typename _Iterator, typename _OutputIterator>
      _OutputIterator
      operator()(_Iterator __first, _Iterator __last, _OutputIterator __result, /*vec*/ ::std::true_type) const
      {
          return __unseq_backend::__simd_assign(
              __first, __last - __first, __result,
              [](_Iterator __first, _OutputIterator __result) { *__result = ::std::move(*__first); });
      }
  
      template <typename _Iterator, typename _OutputIterator>
      _OutputIterator
      operator()(_Iterator __first, _Iterator __last, _OutputIterator __result, /*vec*/ ::std::false_type) const
      {
          return ::std::move(__first, __last, __result);
      }
  };
  
  template <typename _ExecutionPolicy, typename _Dummy = void>
  struct __brick_move_destroy;
  
  template <typename _ExecutionPolicy>
  struct __brick_move_destroy<_ExecutionPolicy,
                              oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, void>>
  {
      template <typename _Iterator, typename _OutputIterator>
      _OutputIterator
      operator()(_Iterator __first, _Iterator __last, _OutputIterator __result, /*vec*/ ::std::true_type) const
      {
          using _IteratorValueType = typename ::std::iterator_traits<_Iterator>::value_type;
  
          return __unseq_backend::__simd_assign(__first, __last - __first, __result,
                                                [](_Iterator __first, _OutputIterator __result) {
                                                    *__result = ::std::move(*__first);
                                                    (*__first).~_IteratorValueType();
                                                });
      }
  
      template <typename _Iterator, typename _OutputIterator>
      _OutputIterator
      operator()(_Iterator __first, _Iterator __last, _OutputIterator __result, /*vec*/ ::std::false_type) const
      {
          using _IteratorValueType = typename ::std::iterator_traits<_Iterator>::value_type;
  
          for (; __first != __last; ++__first, ++__result)
          {
              *__result = ::std::move(*__first);
              (*__first).~_IteratorValueType();
          }
          return __result;
      }
  };
  
  //------------------------------------------------------------------------
  // swap_ranges
  //------------------------------------------------------------------------
  template <class _ForwardIterator, class _OutputIterator>
  _OutputIterator
  __brick_swap_ranges(_ForwardIterator __first, _ForwardIterator __last, _OutputIterator __result,
                      /*vector=*/::std::false_type) noexcept
  {
      return ::std::swap_ranges(__first, __last, __result);
  }
  
  template <class _ForwardIterator, class _OutputIterator>
  _OutputIterator
  __brick_swap_ranges(_ForwardIterator __first, _ForwardIterator __last, _OutputIterator __result,
                      /*vector=*/::std::true_type) noexcept
  {
      using ::std::iter_swap;
      return __unseq_backend::__simd_assign(__first, __last - __first, __result,
                                            iter_swap<_ForwardIterator, _OutputIterator>);
  }
  
  //------------------------------------------------------------------------
  // copy_if
  //------------------------------------------------------------------------
  template <class _ForwardIterator, class _OutputIterator, class _UnaryPredicate>
  _OutputIterator
  __brick_copy_if(_ForwardIterator __first, _ForwardIterator __last, _OutputIterator __result, _UnaryPredicate __pred,
                  /*vector=*/::std::false_type) noexcept
  {
      return ::std::copy_if(__first, __last, __result, __pred);
  }
  
  template <class _ForwardIterator, class _OutputIterator, class _UnaryPredicate>
  _OutputIterator
  __brick_copy_if(_ForwardIterator __first, _ForwardIterator __last, _OutputIterator __result, _UnaryPredicate __pred,
                  /*vector=*/::std::true_type) noexcept
  {
  #if (_PSTL_MONOTONIC_PRESENT || _ONEDPL_MONOTONIC_PRESENT)
      return __unseq_backend::__simd_copy_if(__first, __last - __first, __result, __pred);
  #else
      return ::std::copy_if(__first, __last, __result, __pred);
  #endif
  }
  
  // TODO: Try to use transform_reduce for combining __brick_copy_if_phase1 on IsVector.
  template <class _DifferenceType, class _ForwardIterator, class _UnaryPredicate>
  ::std::pair<_DifferenceType, _DifferenceType>
  __brick_calc_mask_1(_ForwardIterator __first, _ForwardIterator __last, bool* __restrict __mask, _UnaryPredicate __pred,
                      /*vector=*/::std::false_type) noexcept
  {
      auto __count_true = _DifferenceType(0);
      auto __size = __last - __first;
  
      static_assert(__is_random_access_iterator<_ForwardIterator>::value,
                    "Pattern-brick error. Should be a random access iterator.");
  
      for (; __first != __last; ++__first, ++__mask)
      {
          *__mask = __pred(*__first);
          if (*__mask)
          {
              ++__count_true;
          }
      }
      return ::std::make_pair(__count_true, __size - __count_true);
  }
  
  template <class _DifferenceType, class _RandomAccessIterator, class _UnaryPredicate>
  ::std::pair<_DifferenceType, _DifferenceType>
  __brick_calc_mask_1(_RandomAccessIterator __first, _RandomAccessIterator __last, bool* __mask, _UnaryPredicate __pred,
                      /*vector=*/::std::true_type) noexcept
  {
      auto __result = __unseq_backend::__simd_calc_mask_1(__first, __last - __first, __mask, __pred);
      return ::std::make_pair(__result, (__last - __first) - __result);
  }
  
  template <class _ForwardIterator, class _OutputIterator, class _Assigner>
  void
  __brick_copy_by_mask(_ForwardIterator __first, _ForwardIterator __last, _OutputIterator __result, bool* __mask,
                       _Assigner __assigner, /*vector=*/::std::false_type) noexcept
  {
      for (; __first != __last; ++__first, ++__mask)
      {
          if (*__mask)
          {
              __assigner(__first, __result);
              ++__result;
          }
      }
  }
  
  template <class _ForwardIterator, class _OutputIterator, class _Assigner>
  void
  __brick_copy_by_mask(_ForwardIterator __first, _ForwardIterator __last, _OutputIterator __result,
                       bool* __restrict __mask, _Assigner __assigner, /*vector=*/::std::true_type) noexcept
  {
  #if (_PSTL_MONOTONIC_PRESENT || _ONEDPL_MONOTONIC_PRESENT)
      __unseq_backend::__simd_copy_by_mask(__first, __last - __first, __result, __mask, __assigner);
  #else
      __internal::__brick_copy_by_mask(__first, __last, __result, __mask, __assigner, ::std::false_type());
  #endif
  }
  
  template <class _ForwardIterator, class _OutputIterator1, class _OutputIterator2>
  void
  __brick_partition_by_mask(_ForwardIterator __first, _ForwardIterator __last, _OutputIterator1 __out_true,
                            _OutputIterator2 __out_false, bool* __mask, /*vector=*/::std::false_type) noexcept
  {
      for (; __first != __last; ++__first, ++__mask)
      {
          if (*__mask)
          {
              *__out_true = *__first;
              ++__out_true;
          }
          else
          {
              *__out_false = *__first;
              ++__out_false;
          }
      }
  }
  
  template <class _RandomAccessIterator, class _OutputIterator1, class _OutputIterator2>
  void
  __brick_partition_by_mask(_RandomAccessIterator __first, _RandomAccessIterator __last, _OutputIterator1 __out_true,
                            _OutputIterator2 __out_false, bool* __mask, /*vector=*/::std::true_type) noexcept
  {
  #if (_PSTL_MONOTONIC_PRESENT || _ONEDPL_MONOTONIC_PRESENT)
      __unseq_backend::__simd_partition_by_mask(__first, __last - __first, __out_true, __out_false, __mask);
  #else
      __internal::__brick_partition_by_mask(__first, __last, __out_true, __out_false, __mask, ::std::false_type());
  #endif
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator, class _OutputIterator, class _UnaryPredicate, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _OutputIterator>
  __pattern_copy_if(_ExecutionPolicy&&, _ForwardIterator __first, _ForwardIterator __last, _OutputIterator __result,
                    _UnaryPredicate __pred, _IsVector __is_vector, /*parallel=*/::std::false_type) noexcept
  {
      return __internal::__brick_copy_if(__first, __last, __result, __pred, __is_vector);
  }
  
  template <class _ExecutionPolicy, class _RandomAccessIterator, class _OutputIterator, class _UnaryPredicate,
            class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _OutputIterator>
  __pattern_copy_if(_ExecutionPolicy&& __exec, _RandomAccessIterator __first, _RandomAccessIterator __last,
                    _OutputIterator __result, _UnaryPredicate __pred, _IsVector __is_vector,
                    /*parallel=*/::std::true_type)
  {
      typedef typename ::std::iterator_traits<_RandomAccessIterator>::difference_type _DifferenceType;
      const _DifferenceType __n = __last - __first;
      if (_DifferenceType(1) < __n)
      {
          __par_backend::__buffer<_ExecutionPolicy, bool> __mask_buf(__n);
          return __except_handler([&__exec, __n, __first, __result, __is_vector, __pred, &__mask_buf]() {
              bool* __mask = __mask_buf.get();
              _DifferenceType __m{};
              __par_backend::__parallel_strict_scan(
                  ::std::forward<_ExecutionPolicy>(__exec), __n, _DifferenceType(0),
                  [=](_DifferenceType __i, _DifferenceType __len) { // Reduce
                      return __internal::__brick_calc_mask_1<_DifferenceType>(__first + __i, __first + (__i + __len),
                                                                              __mask + __i, __pred, __is_vector)
                          .first;
                  },
                  ::std::plus<_DifferenceType>(),                                              // Combine
                  [=](_DifferenceType __i, _DifferenceType __len, _DifferenceType __initial) { // Scan
                      __brick_copy_by_mask(__first + __i, __first + (__i + __len), __result + __initial, __mask + __i,
                                           [](_RandomAccessIterator __x, _OutputIterator __z) { *__z = *__x; },
                                           __is_vector);
                  },
                  [&__m](_DifferenceType __total) { __m = __total; });
              return __result + __m;
          });
      }
      // trivial sequence - use serial algorithm
      return __internal::__brick_copy_if(__first, __last, __result, __pred, __is_vector);
  }
  
  //------------------------------------------------------------------------
  // count
  //------------------------------------------------------------------------
  template <class _ForwardIterator, class _Predicate>
  typename ::std::iterator_traits<_ForwardIterator>::difference_type
  __brick_count(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred,
                /* is_vector = */ ::std::true_type) noexcept
  {
      return __unseq_backend::__simd_count(__first, __last - __first, __pred);
  }
  
  template <class _ForwardIterator, class _Predicate>
  typename ::std::iterator_traits<_ForwardIterator>::difference_type
  __brick_count(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred,
                /* is_vector = */ ::std::false_type) noexcept
  {
      return ::std::count_if(__first, __last, __pred);
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator, class _Predicate, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<
      _ExecutionPolicy, typename ::std::iterator_traits<_ForwardIterator>::difference_type>
  __pattern_count(_ExecutionPolicy&&, _ForwardIterator __first, _ForwardIterator __last, _Predicate __pred,
                  /* is_parallel */ ::std::false_type, _IsVector __is_vector) noexcept
  {
      return __internal::__brick_count(__first, __last, __pred, __is_vector);
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator, class _Predicate, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<
      _ExecutionPolicy, typename ::std::iterator_traits<_ForwardIterator>::difference_type>
  __pattern_count(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last, _Predicate __pred,
                  /* is_parallel */ ::std::true_type, _IsVector __is_vector)
  {
      typedef typename ::std::iterator_traits<_ForwardIterator>::difference_type _SizeType;
  
      //trivial pre-checks
      if (__first == __last)
          return _SizeType(0);
  
      return __internal::__except_handler([&]() {
          return __par_backend::__parallel_reduce(
              ::std::forward<_ExecutionPolicy>(__exec), __first, __last, _SizeType(0),
              [__pred, __is_vector](_ForwardIterator __begin, _ForwardIterator __end, _SizeType __value) -> _SizeType {
                  return __value + __internal::__brick_count(__begin, __end, __pred, __is_vector);
              },
              ::std::plus<_SizeType>());
      });
  }
  
  //------------------------------------------------------------------------
  // unique
  //------------------------------------------------------------------------
  
  template <class _ForwardIterator, class _BinaryPredicate>
  _ForwardIterator
  __brick_unique(_ForwardIterator __first, _ForwardIterator __last, _BinaryPredicate __pred,
                 /*is_vector=*/::std::false_type) noexcept
  {
      return ::std::unique(__first, __last, __pred);
  }
  
  template <class _ForwardIterator, class _BinaryPredicate>
  _ForwardIterator
  __brick_unique(_ForwardIterator __first, _ForwardIterator __last, _BinaryPredicate __pred,
                 /*is_vector=*/::std::true_type) noexcept
  {
      _PSTL_PRAGMA_MESSAGE("Vectorized algorithm unimplemented, redirected to serial");
      return ::std::unique(__first, __last, __pred);
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator, class _BinaryPredicate, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _ForwardIterator>
  __pattern_unique(_ExecutionPolicy&&, _ForwardIterator __first, _ForwardIterator __last, _BinaryPredicate __pred,
                   _IsVector __is_vector, /*is_parallel=*/::std::false_type) noexcept
  {
      return __internal::__brick_unique(__first, __last, __pred, __is_vector);
  }
  
  // That function is shared between two algorithms - remove_if (__pattern_remove_if) and unique (pattern unique). But a mask calculation is different.
  // So, a caller passes _CalcMask brick into remove_elements.
  template <class _ExecutionPolicy, class _ForwardIterator, class _CalcMask, class _IsVector>
  _ForwardIterator
  __remove_elements(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last, _CalcMask __calc_mask,
                    _IsVector __is_vector)
  {
      typedef typename ::std::iterator_traits<_ForwardIterator>::difference_type _DifferenceType;
      typedef typename ::std::iterator_traits<_ForwardIterator>::value_type _Tp;
      _DifferenceType __n = __last - __first;
      __par_backend::__buffer<_ExecutionPolicy, bool> __mask_buf(__n);
      // 1. find a first iterator that should be removed
      return __internal::__except_handler([&]() {
          bool* __mask = __mask_buf.get();
          _DifferenceType __min = __par_backend::__parallel_reduce(
              ::std::forward<_ExecutionPolicy>(__exec), _DifferenceType(0), __n, __n,
              [__first, __mask, &__calc_mask, __is_vector](_DifferenceType __i, _DifferenceType __j,
                                                           _DifferenceType __local_min) -> _DifferenceType {
                  // Create mask
                  __calc_mask(__mask + __i, __mask + __j, __first + __i);
  
                  // if minimum was found in a previous range we shouldn't do anymore
                  if (__local_min < __i)
                  {
                      return __local_min;
                  }
                  // find first iterator that should be removed
                  bool* __result =
                      __brick_find_if(__mask + __i, __mask + __j, [](bool __val) { return !__val; }, __is_vector);
                  if (__result - __mask == __j)
                  {
                      return __local_min;
                  }
                  return ::std::min(__local_min, _DifferenceType(__result - __mask));
              },
              [](_DifferenceType __local_min1, _DifferenceType __local_min2) -> _DifferenceType {
                  return ::std::min(__local_min1, __local_min2);
              });
  
          // No elements to remove - exit
          if (__min == __n)
          {
              return __last;
          }
          __n -= __min;
          __first += __min;
  
          __par_backend::__buffer<_ExecutionPolicy, _Tp> __buf(__n);
          _Tp* __result = __buf.get();
          __mask += __min;
          _DifferenceType __m{};
          // 2. Elements that doesn't satisfy pred are moved to result
          __par_backend::__parallel_strict_scan(
              ::std::forward<_ExecutionPolicy>(__exec), __n, _DifferenceType(0),
              [__mask, __is_vector](_DifferenceType __i, _DifferenceType __len) {
                  return __brick_count(__mask + __i, __mask + __i + __len, [](bool __val) { return __val; }, __is_vector);
              },
              ::std::plus<_DifferenceType>(),
              [=](_DifferenceType __i, _DifferenceType __len, _DifferenceType __initial) {
                  __brick_copy_by_mask(__first + __i, __first + __i + __len, __result + __initial, __mask + __i,
                                       [](_ForwardIterator __x, _Tp* __z) {
                                           __invoke_if_else(
                                               ::std::is_trivial<_Tp>(), [&]() { *__z = ::std::move(*__x); },
                                               [&]() { ::new (::std::addressof(*__z)) _Tp(::std::move(*__x)); });
                                       },
                                       __is_vector);
              },
              [&__m](_DifferenceType __total) { __m = __total; });
  
          // 3. Elements from result are moved to [first, last)
          __par_backend::__parallel_for(
              ::std::forward<_ExecutionPolicy>(__exec), __result, __result + __m,
              [__result, __first, __is_vector](_Tp* __i, _Tp* __j) {
                  __invoke_if_else(
                      ::std::is_trivial<_Tp>(),
                      [&]() { __brick_move<_ExecutionPolicy>{}(__i, __j, __first + (__i - __result), __is_vector); },
                      [&]() {
                          __brick_move_destroy<_ExecutionPolicy>{}(__i, __j, __first + (__i - __result), __is_vector);
                      });
              });
          return __first + __m;
      });
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator, class _BinaryPredicate, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _ForwardIterator>
  __pattern_unique(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last, _BinaryPredicate __pred,
                   _IsVector __is_vector, /*is_parallel=*/::std::true_type)
  {
      typedef typename ::std::iterator_traits<_ForwardIterator>::reference _ReferenceType;
  
      if (__first == __last)
      {
          return __last;
      }
      if (__first + 1 == __last || __first + 2 == __last)
      {
          // Trivial sequence - use serial algorithm
          return __internal::__brick_unique(__first, __last, __pred, __is_vector);
      }
      return __internal::__remove_elements(
          ::std::forward<_ExecutionPolicy>(__exec), ++__first, __last,
          [&__pred, __is_vector](bool* __b, bool* __e, _ForwardIterator __it) {
              __brick_walk3(__b, __e, __it - 1, __it,
                            [&__pred](bool& __x, _ReferenceType __y, _ReferenceType __z) { __x = !__pred(__y, __z); },
                            __is_vector);
          },
          __is_vector);
  }
  
  //------------------------------------------------------------------------
  // unique_copy
  //------------------------------------------------------------------------
  
  template <class _ForwardIterator, class OutputIterator, class _BinaryPredicate>
  OutputIterator
  __brick_unique_copy(_ForwardIterator __first, _ForwardIterator __last, OutputIterator __result, _BinaryPredicate __pred,
                      /*vector=*/::std::false_type) noexcept
  {
      return ::std::unique_copy(__first, __last, __result, __pred);
  }
  
  template <class _RandomAccessIterator, class OutputIterator, class _BinaryPredicate>
  OutputIterator
  __brick_unique_copy(_RandomAccessIterator __first, _RandomAccessIterator __last, OutputIterator __result,
                      _BinaryPredicate __pred, /*vector=*/::std::true_type) noexcept
  {
  #if (_PSTL_MONOTONIC_PRESENT || _ONEDPL_MONOTONIC_PRESENT)
      return __unseq_backend::__simd_unique_copy(__first, __last - __first, __result, __pred);
  #else
      return ::std::unique_copy(__first, __last, __result, __pred);
  #endif
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator, class _OutputIterator, class _BinaryPredicate,
            class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _OutputIterator>
  __pattern_unique_copy(_ExecutionPolicy&&, _ForwardIterator __first, _ForwardIterator __last, _OutputIterator __result,
                        _BinaryPredicate __pred, _IsVector __is_vector, /*parallel=*/::std::false_type) noexcept
  {
      return __internal::__brick_unique_copy(__first, __last, __result, __pred, __is_vector);
  }
  
  template <class _DifferenceType, class _RandomAccessIterator, class _BinaryPredicate>
  _DifferenceType
  __brick_calc_mask_2(_RandomAccessIterator __first, _RandomAccessIterator __last, bool* __restrict __mask,
                      _BinaryPredicate __pred, /*vector=*/::std::false_type) noexcept
  {
      _DifferenceType __count = 0;
      for (; __first != __last; ++__first, ++__mask)
      {
          *__mask = !__pred(*__first, *(__first - 1));
          __count += *__mask;
      }
      return __count;
  }
  
  template <class _DifferenceType, class _RandomAccessIterator, class _BinaryPredicate>
  _DifferenceType
  __brick_calc_mask_2(_RandomAccessIterator __first, _RandomAccessIterator __last, bool* __restrict __mask,
                      _BinaryPredicate __pred, /*vector=*/::std::true_type) noexcept
  {
      return __unseq_backend::__simd_calc_mask_2(__first, __last - __first, __mask, __pred);
  }
  
  template <class _ExecutionPolicy, class _RandomAccessIterator, class _OutputIterator, class _BinaryPredicate,
            class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _OutputIterator>
  __pattern_unique_copy(_ExecutionPolicy&& __exec, _RandomAccessIterator __first, _RandomAccessIterator __last,
                        _OutputIterator __result, _BinaryPredicate __pred, _IsVector __is_vector,
                        /*parallel=*/::std::true_type)
  {
      typedef typename ::std::iterator_traits<_RandomAccessIterator>::difference_type _DifferenceType;
      const _DifferenceType __n = __last - __first;
      if (_DifferenceType(2) < __n)
      {
          __par_backend::__buffer<_ExecutionPolicy, bool> __mask_buf(__n);
          if (_DifferenceType(2) < __n)
          {
              return __internal::__except_handler([&__exec, __n, __first, __result, __pred, __is_vector, &__mask_buf]() {
                  bool* __mask = __mask_buf.get();
                  _DifferenceType __m{};
                  __par_backend::__parallel_strict_scan(
                      ::std::forward<_ExecutionPolicy>(__exec), __n, _DifferenceType(0),
                      [=](_DifferenceType __i, _DifferenceType __len) -> _DifferenceType { // Reduce
                          _DifferenceType __extra = 0;
                          if (__i == 0)
                          {
                              // Special boundary case
                              __mask[__i] = true;
                              if (--__len == 0)
                                  return 1;
                              ++__i;
                              ++__extra;
                          }
                          return __internal::__brick_calc_mask_2<_DifferenceType>(__first + __i, __first + (__i + __len),
                                                                                  __mask + __i, __pred, __is_vector) +
                                 __extra;
                      },
                      ::std::plus<_DifferenceType>(),                                              // Combine
                      [=](_DifferenceType __i, _DifferenceType __len, _DifferenceType __initial) { // Scan
                          // Phase 2 is same as for __pattern_copy_if
                          __brick_copy_by_mask(__first + __i, __first + (__i + __len), __result + __initial, __mask + __i,
                                               [](_RandomAccessIterator __x, _OutputIterator __z) { *__z = *__x; },
                                               __is_vector);
                      },
                      [&__m](_DifferenceType __total) { __m = __total; });
                  return __result + __m;
              });
          }
      }
      // trivial sequence - use serial algorithm
      return __internal::__brick_unique_copy(__first, __last, __result, __pred, __is_vector);
  }
  
  //------------------------------------------------------------------------
  // reverse
  //------------------------------------------------------------------------
  template <class _BidirectionalIterator>
  void
  __brick_reverse(_BidirectionalIterator __first, _BidirectionalIterator __last,
                  /*__is_vector=*/::std::false_type) noexcept
  {
      ::std::reverse(__first, __last);
  }
  
  template <class _BidirectionalIterator>
  void
  __brick_reverse(_BidirectionalIterator __first, _BidirectionalIterator __last,
                  /*__is_vector=*/::std::true_type) noexcept
  {
      typedef typename ::std::iterator_traits<_BidirectionalIterator>::reference _ReferenceType;
  
      const auto __n = (__last - __first) / 2;
      __unseq_backend::__simd_walk_2(__first, __n, ::std::reverse_iterator<_BidirectionalIterator>(__last),
                                     [](_ReferenceType __x, _ReferenceType __y) {
                                         using ::std::swap;
                                         swap(__x, __y);
                                     });
  }
  
  // this brick is called in parallel version, so we can use iterator arithmetic
  template <class _BidirectionalIterator>
  void
  __brick_reverse(_BidirectionalIterator __first, _BidirectionalIterator __last, _BidirectionalIterator __d_last,
                  /*is_vector=*/::std::false_type) noexcept
  {
      for (--__d_last; __first != __last; ++__first, --__d_last)
      {
          using ::std::iter_swap;
          iter_swap(__first, __d_last);
      }
  }
  
  // this brick is called in parallel version, so we can use iterator arithmetic
  template <class _BidirectionalIterator>
  void
  __brick_reverse(_BidirectionalIterator __first, _BidirectionalIterator __last, _BidirectionalIterator __d_last,
                  /*is_vector=*/::std::true_type) noexcept
  {
      typedef typename ::std::iterator_traits<_BidirectionalIterator>::reference _ReferenceType;
  
      __unseq_backend::__simd_walk_2(__first, __last - __first, ::std::reverse_iterator<_BidirectionalIterator>(__d_last),
                                     [](_ReferenceType __x, _ReferenceType __y) {
                                         using ::std::swap;
                                         swap(__x, __y);
                                     });
  }
  
  template <class _ExecutionPolicy, class _BidirectionalIterator, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, void>
  __pattern_reverse(_ExecutionPolicy&&, _BidirectionalIterator __first, _BidirectionalIterator __last,
                    _IsVector _is_vector,
                    /*is_parallel=*/::std::false_type) noexcept
  {
      __internal::__brick_reverse(__first, __last, _is_vector);
  }
  
  template <class _ExecutionPolicy, class _BidirectionalIterator, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, void>
  __pattern_reverse(_ExecutionPolicy&& __exec, _BidirectionalIterator __first, _BidirectionalIterator __last,
                    _IsVector __is_vector, /*is_parallel=*/::std::true_type)
  {
      __par_backend::__parallel_for(
          ::std::forward<_ExecutionPolicy>(__exec), __first, __first + (__last - __first) / 2,
          [__is_vector, __first, __last](_BidirectionalIterator __inner_first, _BidirectionalIterator __inner_last) {
              __internal::__brick_reverse(__inner_first, __inner_last, __last - (__inner_first - __first), __is_vector);
          });
  }
  
  //------------------------------------------------------------------------
  // reverse_copy
  //------------------------------------------------------------------------
  
  template <class _BidirectionalIterator, class _OutputIterator>
  _OutputIterator
  __brick_reverse_copy(_BidirectionalIterator __first, _BidirectionalIterator __last, _OutputIterator __d_first,
                       /*is_vector=*/::std::false_type) noexcept
  {
      return ::std::reverse_copy(__first, __last, __d_first);
  }
  
  template <class _BidirectionalIterator, class _OutputIterator>
  _OutputIterator
  __brick_reverse_copy(_BidirectionalIterator __first, _BidirectionalIterator __last, _OutputIterator __d_first,
                       /*is_vector=*/::std::true_type) noexcept
  {
      typedef typename ::std::iterator_traits<_BidirectionalIterator>::reference _ReferenceType1;
      typedef typename ::std::iterator_traits<_OutputIterator>::reference _ReferenceType2;
  
      return __unseq_backend::__simd_walk_2(::std::reverse_iterator<_BidirectionalIterator>(__last), __last - __first,
                                            __d_first, [](_ReferenceType1 __x, _ReferenceType2 __y) { __y = __x; });
  }
  
  template <class _ExecutionPolicy, class _BidirectionalIterator, class _OutputIterator, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _OutputIterator>
  __pattern_reverse_copy(_ExecutionPolicy&&, _BidirectionalIterator __first, _BidirectionalIterator __last,
                         _OutputIterator __d_first, _IsVector __is_vector, /*is_parallel=*/::std::false_type) noexcept
  {
      return __internal::__brick_reverse_copy(__first, __last, __d_first, __is_vector);
  }
  
  template <class _ExecutionPolicy, class _BidirectionalIterator, class _OutputIterator, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _OutputIterator>
  __pattern_reverse_copy(_ExecutionPolicy&& __exec, _BidirectionalIterator __first, _BidirectionalIterator __last,
                         _OutputIterator __d_first, _IsVector __is_vector, /*is_parallel=*/::std::true_type)
  {
      auto __len = __last - __first;
      __par_backend::__parallel_for(::std::forward<_ExecutionPolicy>(__exec), __first, __last,
                                    [__is_vector, __first, __len, __d_first](_BidirectionalIterator __inner_first,
                                                                             _BidirectionalIterator __inner_last) {
                                        __internal::__brick_reverse_copy(__inner_first, __inner_last,
                                                                         __d_first + (__len - (__inner_last - __first)),
                                                                         __is_vector);
                                    });
      return __d_first + __len;
  }
  
  //------------------------------------------------------------------------
  // rotate
  //------------------------------------------------------------------------
  template <class _ForwardIterator>
  _ForwardIterator
  __brick_rotate(_ForwardIterator __first, _ForwardIterator __middle, _ForwardIterator __last,
                 /*is_vector=*/::std::false_type) noexcept
  {
  #if (_PSTL_CPP11_STD_ROTATE_BROKEN || _ONEDPL_CPP11_STD_ROTATE_BROKEN)
      ::std::rotate(__first, __middle, __last);
      return ::std::next(__first, ::std::distance(__middle, __last));
  #else
      return ::std::rotate(__first, __middle, __last);
  #endif
  }
  
  template <class _ForwardIterator>
  _ForwardIterator
  __brick_rotate(_ForwardIterator __first, _ForwardIterator __middle, _ForwardIterator __last,
                 /*is_vector=*/::std::true_type) noexcept
  {
      auto __n = __last - __first;
      auto __m = __middle - __first;
      const _ForwardIterator __ret = __first + (__last - __middle);
  
      bool __is_left = (__m <= __n / 2);
      if (!__is_left)
          __m = __n - __m;
  
      while (__n > 1 && __m > 0)
      {
          using ::std::iter_swap;
          const auto __m_2 = __m * 2;
          if (__is_left)
          {
              for (; __last - __first >= __m_2; __first += __m)
              {
                  __unseq_backend::__simd_assign(__first, __m, __first + __m,
                                                 iter_swap<_ForwardIterator, _ForwardIterator>);
              }
          }
          else
          {
              for (; __last - __first >= __m_2; __last -= __m)
              {
                  __unseq_backend::__simd_assign(__last - __m, __m, __last - __m_2,
                                                 iter_swap<_ForwardIterator, _ForwardIterator>);
              }
          }
          __is_left = !__is_left;
          __m = __n % __m;
          __n = __last - __first;
      }
  
      return __ret;
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _ForwardIterator>
  __pattern_rotate(_ExecutionPolicy&&, _ForwardIterator __first, _ForwardIterator __middle, _ForwardIterator __last,
                   _IsVector __is_vector, /*is_parallel=*/::std::false_type) noexcept
  {
      return __internal::__brick_rotate(__first, __middle, __last, __is_vector);
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _ForwardIterator>
  __pattern_rotate(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __middle,
                   _ForwardIterator __last, _IsVector __is_vector, /*is_parallel=*/::std::true_type)
  {
      typedef typename ::std::iterator_traits<_ForwardIterator>::value_type _Tp;
      auto __n = __last - __first;
      auto __m = __middle - __first;
      if (__m <= __n / 2)
      {
          __par_backend::__buffer<_ExecutionPolicy, _Tp> __buf(__n - __m);
          return __except_handler([&__exec, __n, __m, __first, __middle, __last, __is_vector, &__buf]() {
              _Tp* __result = __buf.get();
              __par_backend::__parallel_for(
                  ::std::forward<_ExecutionPolicy>(__exec), __middle, __last,
                  [__middle, __result, __is_vector](_ForwardIterator __b, _ForwardIterator __e) {
                      __internal::__brick_uninitialized_move(__b, __e, __result + (__b - __middle), __is_vector);
                  });
  
              __par_backend::__parallel_for(::std::forward<_ExecutionPolicy>(__exec), __first, __middle,
                                            [__last, __middle, __is_vector](_ForwardIterator __b, _ForwardIterator __e) {
                                                __brick_move<_ExecutionPolicy>{}(__b, __e, __b + (__last - __middle),
                                                                                 __is_vector);
                                            });
  
              __par_backend::__parallel_for(::std::forward<_ExecutionPolicy>(__exec), __result, __result + (__n - __m),
                                            [__first, __result, __is_vector](_Tp* __b, _Tp* __e) {
                                                __brick_move_destroy<_ExecutionPolicy>{}(
                                                    __b, __e, __first + (__b - __result), __is_vector);
                                            });
  
              return __first + (__last - __middle);
          });
      }
      else
      {
          __par_backend::__buffer<_ExecutionPolicy, _Tp> __buf(__m);
          return __except_handler([&__exec, __n, __m, __first, __middle, __last, __is_vector, &__buf]() {
              _Tp* __result = __buf.get();
              __par_backend::__parallel_for(::std::forward<_ExecutionPolicy>(__exec), __first, __middle,
                                            [__first, __result, __is_vector](_ForwardIterator __b, _ForwardIterator __e) {
                                                __internal::__brick_uninitialized_move(
                                                    __b, __e, __result + (__b - __first), __is_vector);
                                            });
  
              __par_backend::__parallel_for(::std::forward<_ExecutionPolicy>(__exec), __middle, __last,
                                            [__first, __middle, __is_vector](_ForwardIterator __b, _ForwardIterator __e) {
                                                __brick_move<_ExecutionPolicy>{}(__b, __e, __first + (__b - __middle),
                                                                                 __is_vector);
                                            });
  
              __par_backend::__parallel_for(::std::forward<_ExecutionPolicy>(__exec), __result, __result + __m,
                                            [__n, __m, __first, __result, __is_vector](_Tp* __b, _Tp* __e) {
                                                __brick_move_destroy<_ExecutionPolicy>{}(
                                                    __b, __e, __first + ((__n - __m) + (__b - __result)), __is_vector);
                                            });
  
              return __first + (__last - __middle);
          });
      }
  }
  
  //------------------------------------------------------------------------
  // rotate_copy
  //------------------------------------------------------------------------
  
  template <class _ExecutionPolicy, class _ForwardIterator, class _OutputIterator>
  _OutputIterator
  __brick_rotate_copy(_ExecutionPolicy&&, _ForwardIterator __first, _ForwardIterator __middle, _ForwardIterator __last,
                      _OutputIterator __result, /*__is_vector=*/::std::false_type) noexcept
  {
      return ::std::rotate_copy(__first, __middle, __last, __result);
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator, class _OutputIterator>
  _OutputIterator
  __brick_rotate_copy(_ExecutionPolicy&&, _ForwardIterator __first, _ForwardIterator __middle, _ForwardIterator __last,
                      _OutputIterator __result, /*__is_vector=*/::std::true_type) noexcept
  {
      _OutputIterator __res = __brick_copy<_ExecutionPolicy>{}(__middle, __last, __result, ::std::true_type());
      return __brick_copy<_ExecutionPolicy>{}(__first, __middle, __res, ::std::true_type());
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator, class _OutputIterator, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _OutputIterator>
  __pattern_rotate_copy(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __middle,
                        _ForwardIterator __last, _OutputIterator __result, _IsVector __is_vector,
                        /*is_parallel=*/::std::false_type) noexcept
  {
      return __internal::__brick_rotate_copy(::std::forward<_ExecutionPolicy>(__exec), __first, __middle, __last,
                                             __result, __is_vector);
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator, class _OutputIterator, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _OutputIterator>
  __pattern_rotate_copy(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __middle,
                        _ForwardIterator __last, _OutputIterator __result, _IsVector __is_vector,
                        /*is_parallel=*/::std::true_type)
  {
      __par_backend::__parallel_for(
          ::std::forward<_ExecutionPolicy>(__exec), __first, __last,
          [__first, __last, __middle, __result, __is_vector](_ForwardIterator __b, _ForwardIterator __e) {
              __brick_copy<_ExecutionPolicy> __copy{};
              if (__b > __middle)
              {
                  __copy(__b, __e, __result + (__b - __middle), __is_vector);
              }
              else
              {
                  _OutputIterator __new_result = __result + ((__last - __middle) + (__b - __first));
                  if (__e < __middle)
                  {
                      __copy(__b, __e, __new_result, __is_vector);
                  }
                  else
                  {
                      __copy(__b, __middle, __new_result, __is_vector);
                      __copy(__middle, __e, __result, __is_vector);
                  }
              }
          });
      return __result + (__last - __first);
  }
  
  //------------------------------------------------------------------------
  // is_partitioned
  //------------------------------------------------------------------------
  
  template <class _ForwardIterator, class _UnaryPredicate>
  bool
  __brick_is_partitioned(_ForwardIterator __first, _ForwardIterator __last, _UnaryPredicate __pred,
                         /*is_vector=*/::std::false_type) noexcept
  {
      return ::std::is_partitioned(__first, __last, __pred);
  }
  
  template <class _ForwardIterator, class _UnaryPredicate>
  bool
  __brick_is_partitioned(_ForwardIterator __first, _ForwardIterator __last, _UnaryPredicate __pred,
                         /*is_vector=*/::std::true_type) noexcept
  {
      typedef typename ::std::iterator_traits<_ForwardIterator>::difference_type _SizeType;
      if (__first == __last)
      {
          return true;
      }
      else
      {
          _ForwardIterator __result = __unseq_backend::__simd_first(
              __first, _SizeType(0), __last - __first,
              [&__pred](_ForwardIterator __it, _SizeType __i) { return !__pred(__it[__i]); });
          if (__result == __last)
          {
              return true;
          }
          else
          {
              ++__result;
              return !__unseq_backend::__simd_or(__result, __last - __result, __pred);
          }
      }
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator, class _UnaryPredicate, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, bool>
  __pattern_is_partitioned(_ExecutionPolicy&&, _ForwardIterator __first, _ForwardIterator __last, _UnaryPredicate __pred,
                           _IsVector __is_vector, /*is_parallel=*/::std::false_type) noexcept
  {
      return __internal::__brick_is_partitioned(__first, __last, __pred, __is_vector);
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator, class _UnaryPredicate, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, bool>
  __pattern_is_partitioned(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last,
                           _UnaryPredicate __pred, _IsVector __is_vector, /*is_parallel=*/::std::true_type)
  {
      //trivial pre-checks
      if (__first == __last)
          return true;
  
      return __internal::__except_handler([&]() {
          // State of current range:
          // broken     - current range is not partitioned by pred
          // all_true   - all elements in current range satisfy pred
          // all_false  - all elements in current range don't satisfy pred
          // true_false - elements satisfy pred are placed before elements that don't satisfy pred
          enum _ReduceRes
          {
              __not_init = -1,
              __broken,
              __all_true,
              __all_false,
              __true_false
          };
          // Array with states that we'll have when state from the left branch is merged with state from the right branch.
          // State is calculated by formula: new_state = table[left_state * 4 + right_state]
          const _ReduceRes __table[] = {__broken,     __broken,     __broken,     __broken, __broken,    __all_true,
                                        __true_false, __true_false, __broken,     __broken, __all_false, __broken,
                                        __broken,     __broken,     __true_false, __broken};
          struct _ReduceType
          {
              _ReduceRes __val;
              _ForwardIterator __pos;
          };
          //a commutative combiner
          auto __combine = [&__table](_ReduceType __x, _ReduceType __y) {
              return __x.__pos > __y.__pos ? _ReduceType{__table[__y.__val * 4 + __x.__val], __y.__pos}
                                           : _ReduceType{__table[__x.__val * 4 + __y.__val], __x.__pos};
          };
  
          const _ReduceType __identity{__not_init, __last};
  
          _ReduceType __result = __par_backend::__parallel_reduce(
              ::std::forward<_ExecutionPolicy>(__exec), __first, __last, __identity,
              [&__pred, __combine, __is_vector](_ForwardIterator __i, _ForwardIterator __j,
                                                _ReduceType __value) -> _ReduceType {
                  if (__value.__val == __broken)
                      return _ReduceType{__broken, __i};
  
                  _ReduceType __res{__not_init, __i};
                  // if first element satisfy pred
                  if (__pred(*__i))
                  {
                      // find first element that don't satisfy pred
                      _ForwardIterator __x =
                          __internal::__brick_find_if(__i + 1, __j, __not_pred<_UnaryPredicate&>(__pred), __is_vector);
                      if (__x != __j)
                      {
                          // find first element after "x" that satisfy pred
                          _ForwardIterator __y = __internal::__brick_find_if(__x + 1, __j, __pred, __is_vector);
                          // if it was found then range isn't partitioned by pred
                          if (__y != __j)
                              return _ReduceType{__broken, __i};
  
                          __res = _ReduceType{__true_false, __i};
                      }
                      else
                          __res = _ReduceType{__all_true, __i};
                  }
                  else
                  { // if first element doesn't satisfy pred
                      // then we should find the first element that satisfy pred.
                      // If we found it then range isn't partitioned by pred
                      if (__internal::__brick_find_if(__i + 1, __j, __pred, __is_vector) != __j)
                          return _ReduceType{__broken, __i};
  
                      __res = _ReduceType{__all_false, __i};
                  }
                  // if we have value from left range then we should calculate the result
                  return (__value.__val == __not_init) ? __res : __combine(__value, __res);
              },
  
              [__combine](_ReduceType __val1, _ReduceType __val2) -> _ReduceType {
                  if (__val1.__val == __not_init)
                      return __val2;
                  if (__val2.__val == __not_init)
                      return __val1;
                  assert(__val1.__val != __not_init && __val2.__val != __not_init);
  
                  if (__val1.__val == __broken || __val2.__val == __broken)
                      return _ReduceType{__broken, __val1.__pos};
                  // calculate the result for new big range
                  return __combine(__val1, __val2);
              });
          return __result.__val != __broken;
      });
  }
  
  //------------------------------------------------------------------------
  // partition
  //------------------------------------------------------------------------
  
  template <class _ForwardIterator, class _UnaryPredicate>
  _ForwardIterator
  __brick_partition(_ForwardIterator __first, _ForwardIterator __last, _UnaryPredicate __pred,
                    /*is_vector=*/::std::false_type) noexcept
  {
      return ::std::partition(__first, __last, __pred);
  }
  
  template <class _ForwardIterator, class _UnaryPredicate>
  _ForwardIterator
  __brick_partition(_ForwardIterator __first, _ForwardIterator __last, _UnaryPredicate __pred,
                    /*is_vector=*/::std::true_type) noexcept
  {
      _PSTL_PRAGMA_MESSAGE("Vectorized algorithm unimplemented, redirected to serial");
      return ::std::partition(__first, __last, __pred);
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator, class _UnaryPredicate, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _ForwardIterator>
  __pattern_partition(_ExecutionPolicy&&, _ForwardIterator __first, _ForwardIterator __last, _UnaryPredicate __pred,
                      _IsVector __is_vector, /*is_parallel=*/::std::false_type) noexcept
  {
      return __internal::__brick_partition(__first, __last, __pred, __is_vector);
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator, class _UnaryPredicate, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _ForwardIterator>
  __pattern_partition(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last,
                      _UnaryPredicate __pred, _IsVector __is_vector, /*is_parallel=*/::std::true_type)
  {
  
      // partitioned range: elements before pivot satisfy pred (true part),
      //                    elements after pivot don't satisfy pred (false part)
      struct _PartitionRange
      {
          _ForwardIterator __begin;
          _ForwardIterator __pivot;
          _ForwardIterator __end;
      };
  
      return __internal::__except_handler([&]() {
          _PartitionRange __init{__last, __last, __last};
  
          // lambda for merging two partitioned ranges to one partitioned range
          auto __reductor = [&__exec, __is_vector](_PartitionRange __val1, _PartitionRange __val2) -> _PartitionRange {
              auto __size1 = __val1.__end - __val1.__pivot;
              auto __size2 = __val2.__pivot - __val2.__begin;
              auto __new_begin = __val2.__begin - (__val1.__end - __val1.__begin);
  
              // if all elements in left range satisfy pred then we can move new pivot to pivot of right range
              if (__val1.__end == __val1.__pivot)
              {
                  return {__new_begin, __val2.__pivot, __val2.__end};
              }
              // if true part of right range greater than false part of left range
              // then we should swap the false part of left range and last part of true part of right range
              else if (__size2 > __size1)
              {
                  __par_backend::__parallel_for(
                      ::std::forward<_ExecutionPolicy>(__exec), __val1.__pivot, __val1.__pivot + __size1,
                      [__val1, __val2, __size1, __is_vector](_ForwardIterator __i, _ForwardIterator __j) {
                          __internal::__brick_swap_ranges(__i, __j, (__val2.__pivot - __size1) + (__i - __val1.__pivot),
                                                          __is_vector);
                      });
                  return {__new_begin, __val2.__pivot - __size1, __val2.__end};
              }
              // else we should swap the first part of false part of left range and true part of right range
              else
              {
                  __par_backend::__parallel_for(
                      ::std::forward<_ExecutionPolicy>(__exec), __val1.__pivot, __val1.__pivot + __size2,
                      [__val1, __val2, __is_vector](_ForwardIterator __i, _ForwardIterator __j) {
                          __internal::__brick_swap_ranges(__i, __j, __val2.__begin + (__i - __val1.__pivot), __is_vector);
                      });
                  return {__new_begin, __val1.__pivot + __size2, __val2.__end};
              }
          };
  
          _PartitionRange __result = __par_backend::__parallel_reduce(
              ::std::forward<_ExecutionPolicy>(__exec), __first, __last, __init,
              [__pred, __is_vector, __reductor](_ForwardIterator __i, _ForwardIterator __j,
                                                _PartitionRange __value) -> _PartitionRange {
                  //1. serial partition
                  _ForwardIterator __pivot = __internal::__brick_partition(__i, __j, __pred, __is_vector);
  
                  // 2. merging of two ranges (left and right respectively)
                  return __reductor(__value, {__i, __pivot, __j});
              },
              __reductor);
          return __result.__pivot;
      });
  }
  
  //------------------------------------------------------------------------
  // stable_partition
  //------------------------------------------------------------------------
  
  template <class _BidirectionalIterator, class _UnaryPredicate>
  _BidirectionalIterator
  __brick_stable_partition(_BidirectionalIterator __first, _BidirectionalIterator __last, _UnaryPredicate __pred,
                           /*__is_vector=*/::std::false_type) noexcept
  {
      return ::std::stable_partition(__first, __last, __pred);
  }
  
  template <class _BidirectionalIterator, class _UnaryPredicate>
  _BidirectionalIterator
  __brick_stable_partition(_BidirectionalIterator __first, _BidirectionalIterator __last, _UnaryPredicate __pred,
                           /*__is_vector=*/::std::true_type) noexcept
  {
      _PSTL_PRAGMA_MESSAGE("Vectorized algorithm unimplemented, redirected to serial");
      return ::std::stable_partition(__first, __last, __pred);
  }
  
  template <class _ExecutionPolicy, class _BidirectionalIterator, class _UnaryPredicate, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _BidirectionalIterator>
  __pattern_stable_partition(_ExecutionPolicy&&, _BidirectionalIterator __first, _BidirectionalIterator __last,
                             _UnaryPredicate __pred, _IsVector __is_vector,
                             /*is_parallelization=*/::std::false_type) noexcept
  {
      return __internal::__brick_stable_partition(__first, __last, __pred, __is_vector);
  }
  
  template <class _ExecutionPolicy, class _BidirectionalIterator, class _UnaryPredicate, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _BidirectionalIterator>
  __pattern_stable_partition(_ExecutionPolicy&& __exec, _BidirectionalIterator __first, _BidirectionalIterator __last,
                             _UnaryPredicate __pred, _IsVector __is_vector,
                             /*is_parallelization=*/::std::true_type)
  {
      // partitioned range: elements before pivot satisfy pred (true part),
      //                    elements after pivot don't satisfy pred (false part)
      struct _PartitionRange
      {
          _BidirectionalIterator __begin;
          _BidirectionalIterator __pivot;
          _BidirectionalIterator __end;
      };
  
      return __internal::__except_handler([&]() {
          _PartitionRange __init{__last, __last, __last};
  
          // lambda for merging two partitioned ranges to one partitioned range
          auto __reductor = [__is_vector](_PartitionRange __val1, _PartitionRange __val2) -> _PartitionRange {
              auto __size1 = __val1.__end - __val1.__pivot;
              auto __new_begin = __val2.__begin - (__val1.__end - __val1.__begin);
  
              // if all elements in left range satisfy pred then we can move new pivot to pivot of right range
              if (__val1.__end == __val1.__pivot)
              {
                  return {__new_begin, __val2.__pivot, __val2.__end};
              }
              // if true part of right range greater than false part of left range
              // then we should swap the false part of left range and last part of true part of right range
              else
              {
                  __internal::__brick_rotate(__val1.__pivot, __val2.__begin, __val2.__pivot, __is_vector);
                  return {__new_begin, __val2.__pivot - __size1, __val2.__end};
              }
          };
  
          _PartitionRange __result = __par_backend::__parallel_reduce(
              ::std::forward<_ExecutionPolicy>(__exec), __first, __last, __init,
              [&__pred, __is_vector, __reductor](_BidirectionalIterator __i, _BidirectionalIterator __j,
                                                 _PartitionRange __value) -> _PartitionRange {
                  //1. serial stable_partition
                  _BidirectionalIterator __pivot = __internal::__brick_stable_partition(__i, __j, __pred, __is_vector);
  
                  // 2. merging of two ranges (left and right respectively)
                  return __reductor(__value, {__i, __pivot, __j});
              },
              __reductor);
          return __result.__pivot;
      });
  }
  
  //------------------------------------------------------------------------
  // partition_copy
  //------------------------------------------------------------------------
  
  template <class _ForwardIterator, class _OutputIterator1, class _OutputIterator2, class _UnaryPredicate>
  ::std::pair<_OutputIterator1, _OutputIterator2>
  __brick_partition_copy(_ForwardIterator __first, _ForwardIterator __last, _OutputIterator1 __out_true,
                         _OutputIterator2 __out_false, _UnaryPredicate __pred, /*is_vector=*/::std::false_type) noexcept
  {
      return ::std::partition_copy(__first, __last, __out_true, __out_false, __pred);
  }
  
  template <class _ForwardIterator, class _OutputIterator1, class _OutputIterator2, class _UnaryPredicate>
  ::std::pair<_OutputIterator1, _OutputIterator2>
  __brick_partition_copy(_ForwardIterator __first, _ForwardIterator __last, _OutputIterator1 __out_true,
                         _OutputIterator2 __out_false, _UnaryPredicate __pred, /*is_vector=*/::std::true_type) noexcept
  {
  #if (_PSTL_MONOTONIC_PRESENT || _ONEDPL_MONOTONIC_PRESENT)
      return __unseq_backend::__simd_partition_copy(__first, __last - __first, __out_true, __out_false, __pred);
  #else
      return ::std::partition_copy(__first, __last, __out_true, __out_false, __pred);
  #endif
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator, class _OutputIterator1, class _OutputIterator2,
            class _UnaryPredicate, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy,
                                                             ::std::pair<_OutputIterator1, _OutputIterator2>>
  __pattern_partition_copy(_ExecutionPolicy&&, _ForwardIterator __first, _ForwardIterator __last,
                           _OutputIterator1 __out_true, _OutputIterator2 __out_false, _UnaryPredicate __pred,
                           _IsVector __is_vector, /*is_parallelization=*/::std::false_type) noexcept
  {
      return __internal::__brick_partition_copy(__first, __last, __out_true, __out_false, __pred, __is_vector);
  }
  
  template <class _ExecutionPolicy, class _RandomAccessIterator, class _OutputIterator1, class _OutputIterator2,
            class _UnaryPredicate, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy,
                                                             ::std::pair<_OutputIterator1, _OutputIterator2>>
  __pattern_partition_copy(_ExecutionPolicy&& __exec, _RandomAccessIterator __first, _RandomAccessIterator __last,
                           _OutputIterator1 __out_true, _OutputIterator2 __out_false, _UnaryPredicate __pred,
                           _IsVector __is_vector, /*is_parallelization=*/::std::true_type)
  {
      typedef typename ::std::iterator_traits<_RandomAccessIterator>::difference_type _DifferenceType;
      typedef ::std::pair<_DifferenceType, _DifferenceType> _ReturnType;
      const _DifferenceType __n = __last - __first;
      if (_DifferenceType(1) < __n)
      {
          __par_backend::__buffer<_ExecutionPolicy, bool> __mask_buf(__n);
          return __internal::__except_handler([&__exec, __n, __first, __out_true, __out_false, __is_vector, __pred,
                                               &__mask_buf]() {
              bool* __mask = __mask_buf.get();
              _ReturnType __m{};
              __par_backend::__parallel_strict_scan(
                  ::std::forward<_ExecutionPolicy>(__exec), __n, ::std::make_pair(_DifferenceType(0), _DifferenceType(0)),
                  [=](_DifferenceType __i, _DifferenceType __len) { // Reduce
                      return __internal::__brick_calc_mask_1<_DifferenceType>(__first + __i, __first + (__i + __len),
                                                                              __mask + __i, __pred, __is_vector);
                  },
                  [](const _ReturnType& __x, const _ReturnType& __y) -> _ReturnType {
                      return ::std::make_pair(__x.first + __y.first, __x.second + __y.second);
                  },                                                                       // Combine
                  [=](_DifferenceType __i, _DifferenceType __len, _ReturnType __initial) { // Scan
                      __internal::__brick_partition_by_mask(__first + __i, __first + (__i + __len),
                                                            __out_true + __initial.first, __out_false + __initial.second,
                                                            __mask + __i, __is_vector);
                  },
                  [&__m](_ReturnType __total) { __m = __total; });
              return ::std::make_pair(__out_true + __m.first, __out_false + __m.second);
          });
      }
      // trivial sequence - use serial algorithm
      return __internal::__brick_partition_copy(__first, __last, __out_true, __out_false, __pred, __is_vector);
  }
  
  //------------------------------------------------------------------------
  // sort
  //------------------------------------------------------------------------
  
  template <class _ExecutionPolicy, class _RandomAccessIterator, class _Compare, class _IsVector,
            class _IsMoveConstructible>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, void>
  __pattern_sort(_ExecutionPolicy&&, _RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp,
                 _IsVector /*is_vector*/, /*is_parallel=*/::std::false_type, _IsMoveConstructible) noexcept
  {
      ::std::sort(__first, __last, __comp);
  }
  
  template <class _ExecutionPolicy, class _RandomAccessIterator, class _Compare, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, void>
  __pattern_sort(_ExecutionPolicy&& __exec, _RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp,
                 _IsVector /*is_vector*/, /*is_parallel=*/::std::true_type, /*is_move_constructible=*/::std::true_type)
  {
      __except_handler([&]() {
          __par_backend::__parallel_stable_sort(::std::forward<_ExecutionPolicy>(__exec), __first, __last, __comp,
                                                [](_RandomAccessIterator __first, _RandomAccessIterator __last,
                                                   _Compare __comp) { ::std::sort(__first, __last, __comp); },
                                                __last - __first);
      });
  }
  
  //------------------------------------------------------------------------
  // stable_sort
  //------------------------------------------------------------------------
  
  template <class _ExecutionPolicy, class _RandomAccessIterator, class _Compare, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, void>
  __pattern_stable_sort(_ExecutionPolicy&&, _RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp,
                        _IsVector /*is_vector*/, /*is_parallel=*/::std::false_type) noexcept
  {
      ::std::stable_sort(__first, __last, __comp);
  }
  
  template <class _ExecutionPolicy, class _RandomAccessIterator, class _Compare, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, void>
  __pattern_stable_sort(_ExecutionPolicy&& __exec, _RandomAccessIterator __first, _RandomAccessIterator __last,
                        _Compare __comp, _IsVector /*is_vector*/, /*is_parallel=*/::std::true_type)
  {
      __internal::__except_handler([&]() {
          __par_backend::__parallel_stable_sort(::std::forward<_ExecutionPolicy>(__exec), __first, __last, __comp,
                                                [](_RandomAccessIterator __first, _RandomAccessIterator __last,
                                                   _Compare __comp) { ::std::stable_sort(__first, __last, __comp); },
                                                __last - __first);
      });
  }
  
  //------------------------------------------------------------------------
  // partial_sort
  //------------------------------------------------------------------------
  
  template <class _ExecutionPolicy, class _RandomAccessIterator, class _Compare, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, void>
  __pattern_partial_sort(_ExecutionPolicy&&, _RandomAccessIterator __first, _RandomAccessIterator __middle,
                         _RandomAccessIterator __last, _Compare __comp, _IsVector,
                         /*is_parallel=*/::std::false_type) noexcept
  {
      ::std::partial_sort(__first, __middle, __last, __comp);
  }
  
  template <class _ExecutionPolicy, class _RandomAccessIterator, class _Compare, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, void>
  __pattern_partial_sort(_ExecutionPolicy&& __exec, _RandomAccessIterator __first, _RandomAccessIterator __middle,
                         _RandomAccessIterator __last, _Compare __comp, _IsVector, /*is_parallel=*/::std::true_type)
  {
      const auto __n = __middle - __first;
      if (__n == 0)
          return;
  
      __except_handler([&]() {
          __par_backend::__parallel_stable_sort(
              ::std::forward<_ExecutionPolicy>(__exec), __first, __last, __comp,
              [__n](_RandomAccessIterator __begin, _RandomAccessIterator __end, _Compare __comp) {
                  if (__n < __end - __begin)
                      ::std::partial_sort(__begin, __begin + __n, __end, __comp);
                  else
                      ::std::sort(__begin, __end, __comp);
              },
              __n);
      });
  }
  
  //------------------------------------------------------------------------
  // partial_sort_copy
  //------------------------------------------------------------------------
  
  template <class _ExecutionPolicy, class _ForwardIterator, class _RandomAccessIterator, class _Compare, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _RandomAccessIterator>
  __pattern_partial_sort_copy(_ExecutionPolicy&&, _ForwardIterator __first, _ForwardIterator __last,
                              _RandomAccessIterator __d_first, _RandomAccessIterator __d_last, _Compare __comp, _IsVector,
                              /*is_parallel=*/::std::false_type) noexcept
  {
      return ::std::partial_sort_copy(__first, __last, __d_first, __d_last, __comp);
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator, class _RandomAccessIterator, class _Compare, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _RandomAccessIterator>
  __pattern_partial_sort_copy(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last,
                              _RandomAccessIterator __d_first, _RandomAccessIterator __d_last, _Compare __comp,
                              _IsVector __is_vector, /*is_parallel=*/::std::true_type)
  {
      if (__last == __first || __d_last == __d_first)
      {
          return __d_first;
      }
      auto __n1 = __last - __first;
      auto __n2 = __d_last - __d_first;
      return __internal::__except_handler([&]() {
          if (__n2 >= __n1)
          {
              __par_backend::__parallel_stable_sort(
                  ::std::forward<_ExecutionPolicy>(__exec), __d_first, __d_first + __n1, __comp,
                  [__first, __d_first, __is_vector](_RandomAccessIterator __i, _RandomAccessIterator __j,
                                                    _Compare __comp) {
                      _ForwardIterator __i1 = __first + (__i - __d_first);
                      _ForwardIterator __j1 = __first + (__j - __d_first);
  
                      // 1. Copy elements from input to output
                      __brick_copy<_ExecutionPolicy>{}(__i1, __j1, __i, __is_vector);
                      // 2. Sort elements in output sequence
                      ::std::sort(__i, __j, __comp);
                  },
                  __n1);
              return __d_first + __n1;
          }
          else
          {
              typedef typename ::std::iterator_traits<_ForwardIterator>::value_type _T1;
              typedef typename ::std::iterator_traits<_RandomAccessIterator>::value_type _T2;
              __par_backend::__buffer<_ExecutionPolicy, _T1> __buf(__n1);
              _T1* __r = __buf.get();
  
              __par_backend::__parallel_stable_sort(::std::forward<_ExecutionPolicy>(__exec), __r, __r + __n1, __comp,
                                                    [__n2, __first, __r](_T1* __i, _T1* __j, _Compare __comp) {
                                                        _ForwardIterator __it = __first + (__i - __r);
  
                                                        // 1. Copy elements from input to raw memory
                                                        for (_T1* __k = __i; __k != __j; ++__k, ++__it)
                                                        {
                                                            ::new (__k) _T2(*__it);
                                                        }
  
                                                        // 2. Sort elements in temporary buffer
                                                        if (__n2 < __j - __i)
                                                            ::std::partial_sort(__i, __i + __n2, __j, __comp);
                                                        else
                                                            ::std::sort(__i, __j, __comp);
                                                    },
                                                    __n2);
  
              // 3. Move elements from temporary buffer to output
              __par_backend::__parallel_for(::std::forward<_ExecutionPolicy>(__exec), __r, __r + __n2,
                                            [__r, __d_first, __is_vector](_T1* __i, _T1* __j) {
                                                __brick_move_destroy<_ExecutionPolicy>{}(
                                                    __i, __j, __d_first + (__i - __r), __is_vector);
                                            });
              __par_backend::__parallel_for(
                  ::std::forward<_ExecutionPolicy>(__exec), __r + __n2, __r + __n1,
                  [__is_vector](_T1* __i, _T1* __j) { __brick_destroy(__i, __j, __is_vector); });
  
              return __d_first + __n2;
          }
      });
  }
  
  //------------------------------------------------------------------------
  // adjacent_find
  //------------------------------------------------------------------------
  template <class _ForwardIterator, class _BinaryPredicate>
  _ForwardIterator
  __brick_adjacent_find(_ForwardIterator __first, _ForwardIterator __last, _BinaryPredicate __pred,
                        /* IsVector = */ ::std::true_type, bool __or_semantic) noexcept
  {
      return __unseq_backend::__simd_adjacent_find(__first, __last, __pred, __or_semantic);
  }
  
  template <class _ForwardIterator, class _BinaryPredicate>
  _ForwardIterator
  __brick_adjacent_find(_ForwardIterator __first, _ForwardIterator __last, _BinaryPredicate __pred,
                        /* IsVector = */ ::std::false_type, bool /* __or_semantic */) noexcept
  {
      return ::std::adjacent_find(__first, __last, __pred);
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator, class _BinaryPredicate, class _IsVector, class _Semantic>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _ForwardIterator>
  __pattern_adjacent_find(_ExecutionPolicy&&, _ForwardIterator __first, _ForwardIterator __last, _BinaryPredicate __pred,
                          /* is_parallel */ ::std::false_type, _IsVector __is_vector, _Semantic) noexcept
  {
      return __internal::__brick_adjacent_find(__first, __last, __pred, __is_vector, _Semantic::value);
  }
  
  template <class _ExecutionPolicy, class _RandomAccessIterator, class _BinaryPredicate, class _IsVector, class _Semantic>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _RandomAccessIterator>
  __pattern_adjacent_find(_ExecutionPolicy&& __exec, _RandomAccessIterator __first, _RandomAccessIterator __last,
                          _BinaryPredicate __pred, /* is_parallel */ ::std::true_type, _IsVector __is_vector,
                          _Semantic __or_semantic)
  {
      if (__last - __first < 2)
          return __last;
  
      return __internal::__except_handler([&]() {
          return __par_backend::__parallel_reduce(
              ::std::forward<_ExecutionPolicy>(__exec), __first, __last, __last,
              [__last, __pred, __is_vector, __or_semantic](_RandomAccessIterator __begin, _RandomAccessIterator __end,
                                                           _RandomAccessIterator __value) -> _RandomAccessIterator {
                  // TODO: investigate performance benefits from the use of shared variable for the result,
                  // checking (compare_and_swap idiom) its __value at __first.
                  if (__or_semantic && __value < __last)
                  { //found
                      return __value;
                  }
  
                  if (__value > __begin)
                  {
                      // modify __end to check the predicate on the boundary __values;
                      // TODO: to use a custom range with boundaries overlapping
                      // TODO: investigate what if we remove "if" below and run algorithm on range [__first, __last-1)
                      // then check the pair [__last-1, __last)
                      if (__end != __last)
                          ++__end;
  
                      //correct the global result iterator if the "brick" returns a local "__last"
                      const _RandomAccessIterator __res =
                          __internal::__brick_adjacent_find(__begin, __end, __pred, __is_vector, __or_semantic);
                      if (__res < __end)
                          __value = __res;
                  }
                  return __value;
              },
              [](_RandomAccessIterator __x, _RandomAccessIterator __y) -> _RandomAccessIterator {
                  return __x < __y ? __x : __y;
              } //reduce a __value
          );
      });
  }
  
  //------------------------------------------------------------------------
  // nth_element
  //------------------------------------------------------------------------
  
  template <class _ExecutionPolicy, class _RandomAccessIterator, class _Compare, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, void>
  __pattern_nth_element(_ExecutionPolicy&&, _RandomAccessIterator __first, _RandomAccessIterator __nth,
                        _RandomAccessIterator __last, _Compare __comp, _IsVector,
                        /*is_parallel=*/::std::false_type) noexcept
  {
      ::std::nth_element(__first, __nth, __last, __comp);
  }
  
  template <class _ExecutionPolicy, class _RandomAccessIterator, class _Compare, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, void>
  __pattern_nth_element(_ExecutionPolicy&& __exec, _RandomAccessIterator __first, _RandomAccessIterator __nth,
                        _RandomAccessIterator __last, _Compare __comp, _IsVector __is_vector,
                        /*is_parallel=*/::std::true_type)
  {
      if (__first == __last || __nth == __last)
      {
          return;
      }
  
      using ::std::iter_swap;
      typedef typename ::std::iterator_traits<_RandomAccessIterator>::value_type _Tp;
      _RandomAccessIterator __x;
      do
      {
          __x = __pattern_partition(::std::forward<_ExecutionPolicy>(__exec), __first + 1, __last,
                                    [&__comp, __first](const _Tp& __x) { return __comp(__x, *__first); }, __is_vector,
                                    /*is_parallel=*/::std::true_type());
          --__x;
          if (__x != __first)
          {
              iter_swap(__first, __x);
          }
          // if x > nth then our new range for partition is [first, x)
          if (__x - __nth > 0)
          {
              __last = __x;
          }
          // if x < nth then our new range for partition is [x, last)
          else if (__x - __nth < 0)
          {
              // if *x == *nth then we start the new partition at the next index where *x != *nth
              while (!__comp(*__nth, *__x) && !__comp(*__x, *__nth) && __x - __nth < 0)
              {
                  ++__x;
              }
              iter_swap(__nth, __x);
              __first = __x;
          }
      } while (__x != __nth);
  }
  
  //------------------------------------------------------------------------
  // fill, fill_n
  //------------------------------------------------------------------------
  template <typename _Tp, typename _ExecutionPolicy>
  struct __brick_fill<_Tp, _ExecutionPolicy,
                      oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, void>>
  {
      const _Tp& __value;
  
      template <typename _ForwardIterator>
      void
      operator()(_ForwardIterator __first, _ForwardIterator __last,
                 /* __is_vector = */ ::std::true_type) const noexcept
      {
          __unseq_backend::__simd_fill_n(__first, __last - __first, __value);
      }
  
      template <typename _ForwardIterator>
      void
      operator()(_ForwardIterator __first, _ForwardIterator __last,
                 /* __is_vector = */ ::std::false_type) const noexcept
      {
          ::std::fill(__first, __last, __value);
      }
  };
  
  template <class _ExecutionPolicy, class _ForwardIterator, class _Tp, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, void>
  __pattern_fill(_ExecutionPolicy&&, _ForwardIterator __first, _ForwardIterator __last, const _Tp& __value,
                 /*is_parallel=*/::std::false_type, _IsVector __is_vector) noexcept
  {
      __brick_fill<_Tp, _ExecutionPolicy>{__value}(__first, __last, __is_vector);
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator, class _Tp, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _ForwardIterator>
  __pattern_fill(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last, const _Tp& __value,
                 /*is_parallel=*/::std::true_type, _IsVector __is_vector)
  {
      return __internal::__except_handler([&__exec, __first, __last, &__value, __is_vector]() {
          __par_backend::__parallel_for(::std::forward<_ExecutionPolicy>(__exec), __first, __last,
                                        [&__value, __is_vector](_ForwardIterator __begin, _ForwardIterator __end) {
                                            __internal::__brick_fill<_Tp, _ExecutionPolicy>{__value}(__begin, __end,
                                                                                                     __is_vector);
                                        });
          return __last;
      });
  }
  
  template <typename _Tp, typename _ExecutionPolicy>
  struct __brick_fill_n<_Tp, _ExecutionPolicy,
                        oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, void>>
  {
      const _Tp& __value;
  
      template <typename _OutputIterator, typename _Size>
      _OutputIterator
      operator()(_OutputIterator __first, _Size __count,
                 /* __is_vector = */ ::std::true_type) const noexcept
      {
          return __unseq_backend::__simd_fill_n(__first, __count, __value);
      }
  
      template <typename _OutputIterator, typename _Size>
      _OutputIterator
      operator()(_OutputIterator __first, _Size __count,
                 /* __is_vector = */ ::std::false_type) const noexcept
      {
          return ::std::fill_n(__first, __count, __value);
      }
  };
  
  template <class _ExecutionPolicy, class _OutputIterator, class _Size, class _Tp, class _IsVector>
  _OutputIterator
  __pattern_fill_n(_ExecutionPolicy&&, _OutputIterator __first, _Size __count, const _Tp& __value,
                   /*is_parallel=*/::std::false_type, _IsVector __is_vector) noexcept
  {
      return __internal::__brick_fill_n<_Tp, _ExecutionPolicy>{__value}(__first, __count, __is_vector);
  }
  
  template <class _ExecutionPolicy, class _OutputIterator, class _Size, class _Tp, class _IsVector>
  _OutputIterator
  __pattern_fill_n(_ExecutionPolicy&& __exec, _OutputIterator __first, _Size __count, const _Tp& __value,
                   /*is_parallel=*/::std::true_type, _IsVector __is_vector)
  {
      return __internal::__pattern_fill(::std::forward<_ExecutionPolicy>(__exec), __first, __first + __count, __value,
                                        ::std::true_type(), __is_vector);
  }
  
  //------------------------------------------------------------------------
  // generate, generate_n
  //------------------------------------------------------------------------
  template <class _RandomAccessIterator, class _Generator>
  void
  __brick_generate(_RandomAccessIterator __first, _RandomAccessIterator __last, _Generator __g,
                   /* is_vector = */ ::std::true_type) noexcept
  {
      __unseq_backend::__simd_generate_n(__first, __last - __first, __g);
  }
  
  template <class _ForwardIterator, class _Generator>
  void
  __brick_generate(_ForwardIterator __first, _ForwardIterator __last, _Generator __g,
                   /* is_vector = */ ::std::false_type) noexcept
  {
      ::std::generate(__first, __last, __g);
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator, class _Generator, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, void>
  __pattern_generate(_ExecutionPolicy&&, _ForwardIterator __first, _ForwardIterator __last, _Generator __g,
                     /*is_parallel=*/::std::false_type, _IsVector __is_vector) noexcept
  {
      __internal::__brick_generate(__first, __last, __g, __is_vector);
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator, class _Generator, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _ForwardIterator>
  __pattern_generate(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last, _Generator __g,
                     /*is_parallel=*/::std::true_type, _IsVector __is_vector)
  {
      return __internal::__except_handler([&]() {
          __par_backend::__parallel_for(::std::forward<_ExecutionPolicy>(__exec), __first, __last,
                                        [__g, __is_vector](_ForwardIterator __begin, _ForwardIterator __end) {
                                            __internal::__brick_generate(__begin, __end, __g, __is_vector);
                                        });
          return __last;
      });
  }
  
  template <class OutputIterator, class Size, class _Generator>
  OutputIterator
  __brick_generate_n(OutputIterator __first, Size __count, _Generator __g, /* is_vector = */ ::std::true_type) noexcept
  {
      return __unseq_backend::__simd_generate_n(__first, __count, __g);
  }
  
  template <class OutputIterator, class Size, class _Generator>
  OutputIterator
  __brick_generate_n(OutputIterator __first, Size __count, _Generator __g, /* is_vector = */ ::std::false_type) noexcept
  {
      return ::std::generate_n(__first, __count, __g);
  }
  
  template <class _ExecutionPolicy, class _OutputIterator, class _Size, class _Generator, class _IsVector>
  _OutputIterator
  __pattern_generate_n(_ExecutionPolicy&&, _OutputIterator __first, _Size __count, _Generator __g,
                       /*is_parallel=*/::std::false_type, _IsVector __is_vector) noexcept
  {
      return __internal::__brick_generate_n(__first, __count, __g, __is_vector);
  }
  
  template <class _ExecutionPolicy, class _OutputIterator, class _Size, class _Generator, class _IsVector>
  _OutputIterator
  __pattern_generate_n(_ExecutionPolicy&& __exec, _OutputIterator __first, _Size __count, _Generator __g,
                       /*is_parallel=*/::std::true_type, _IsVector __is_vector)
  {
      static_assert(__is_random_access_iterator<_OutputIterator>::value,
                    "Pattern-brick error. Should be a random access iterator.");
      return __internal::__pattern_generate(::std::forward<_ExecutionPolicy>(__exec), __first, __first + __count, __g,
                                            ::std::true_type(), __is_vector);
  }
  
  //------------------------------------------------------------------------
  // remove
  //------------------------------------------------------------------------
  
  template <class _ForwardIterator, class _UnaryPredicate>
  _ForwardIterator
  __brick_remove_if(_ForwardIterator __first, _ForwardIterator __last, _UnaryPredicate __pred,
                    /* __is_vector = */ ::std::false_type) noexcept
  {
      return ::std::remove_if(__first, __last, __pred);
  }
  
  template <class _RandomAccessIterator, class _UnaryPredicate>
  _RandomAccessIterator
  __brick_remove_if(_RandomAccessIterator __first, _RandomAccessIterator __last, _UnaryPredicate __pred,
                    /* __is_vector = */ ::std::true_type) noexcept
  {
  #if (_PSTL_MONOTONIC_PRESENT || _ONEDPL_MONOTONIC_PRESENT)
      return __unseq_backend::__simd_remove_if(__first, __last - __first, __pred);
  #else
      return ::std::remove_if(__first, __last, __pred);
  #endif
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator, class _UnaryPredicate, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _ForwardIterator>
  __pattern_remove_if(_ExecutionPolicy&&, _ForwardIterator __first, _ForwardIterator __last, _UnaryPredicate __pred,
                      _IsVector __is_vector, /*is_parallel*/ ::std::false_type) noexcept
  {
      return __internal::__brick_remove_if(__first, __last, __pred, __is_vector);
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator, class _UnaryPredicate, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _ForwardIterator>
  __pattern_remove_if(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last,
                      _UnaryPredicate __pred, _IsVector __is_vector, /*is_parallel*/ ::std::true_type)
  {
      typedef typename ::std::iterator_traits<_ForwardIterator>::reference _ReferenceType;
  
      if (__first == __last || __first + 1 == __last)
      {
          // Trivial sequence - use serial algorithm
          return __internal::__brick_remove_if(__first, __last, __pred, __is_vector);
      }
  
      return __remove_elements(::std::forward<_ExecutionPolicy>(__exec), __first, __last,
                               [&__pred, __is_vector](bool* __b, bool* __e, _ForwardIterator __it) {
                                   __brick_walk2(__b, __e, __it,
                                                 [&__pred](bool& __x, _ReferenceType __y) { __x = !__pred(__y); },
                                                 __is_vector);
                               },
                               __is_vector);
  }
  
  //------------------------------------------------------------------------
  // merge
  //------------------------------------------------------------------------
  
  template <class _ForwardIterator1, class _ForwardIterator2, class _OutputIterator, class _Compare>
  _OutputIterator
  __brick_merge(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2,
                _ForwardIterator2 __last2, _OutputIterator __d_first, _Compare __comp,
                /* __is_vector = */ ::std::false_type) noexcept
  {
      return ::std::merge(__first1, __last1, __first2, __last2, __d_first, __comp);
  }
  
  template <class _ForwardIterator1, class _ForwardIterator2, class _OutputIterator, class _Compare>
  _OutputIterator
  __brick_merge(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2,
                _ForwardIterator2 __last2, _OutputIterator __d_first, _Compare __comp,
                /* __is_vector = */ ::std::true_type) noexcept
  {
      _PSTL_PRAGMA_MESSAGE("Vectorized algorithm unimplemented, redirected to serial");
      return ::std::merge(__first1, __last1, __first2, __last2, __d_first, __comp);
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _OutputIterator,
            class _Compare, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _OutputIterator>
  __pattern_merge(_ExecutionPolicy&&, _ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2,
                  _ForwardIterator2 __last2, _OutputIterator __d_first, _Compare __comp, _IsVector __is_vector,
                  /* is_parallel = */ ::std::false_type) noexcept
  {
      return __internal::__brick_merge(__first1, __last1, __first2, __last2, __d_first, __comp, __is_vector);
  }
  
  template <class _ExecutionPolicy, class _RandomAccessIterator1, class _RandomAccessIterator2, class _OutputIterator,
            class _Compare, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _OutputIterator>
  __pattern_merge(_ExecutionPolicy&& __exec, _RandomAccessIterator1 __first1, _RandomAccessIterator1 __last1,
                  _RandomAccessIterator2 __first2, _RandomAccessIterator2 __last2, _OutputIterator __d_first,
                  _Compare __comp, _IsVector __is_vector, /* is_parallel = */ ::std::true_type)
  {
      __par_backend::__parallel_merge(
          ::std::forward<_ExecutionPolicy>(__exec), __first1, __last1, __first2, __last2, __d_first, __comp,
          [__is_vector](_RandomAccessIterator1 __f1, _RandomAccessIterator1 __l1, _RandomAccessIterator2 __f2,
                        _RandomAccessIterator2 __l2, _OutputIterator __f3, _Compare __comp) {
              return __internal::__brick_merge(__f1, __l1, __f2, __l2, __f3, __comp, __is_vector);
          });
      return __d_first + (__last1 - __first1) + (__last2 - __first2);
  }
  
  //------------------------------------------------------------------------
  // inplace_merge
  //------------------------------------------------------------------------
  template <class _BidirectionalIterator, class _Compare>
  void
  __brick_inplace_merge(_BidirectionalIterator __first, _BidirectionalIterator __middle, _BidirectionalIterator __last,
                        _Compare __comp, /* __is_vector = */ ::std::false_type) noexcept
  {
      ::std::inplace_merge(__first, __middle, __last, __comp);
  }
  
  template <class _BidirectionalIterator, class _Compare>
  void
  __brick_inplace_merge(_BidirectionalIterator __first, _BidirectionalIterator __middle, _BidirectionalIterator __last,
                        _Compare __comp, /* __is_vector = */ ::std::true_type) noexcept
  {
      _PSTL_PRAGMA_MESSAGE("Vectorized algorithm unimplemented, redirected to serial")
      ::std::inplace_merge(__first, __middle, __last, __comp);
  }
  
  template <class _ExecutionPolicy, class _BidirectionalIterator, class _Compare, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, void>
  __pattern_inplace_merge(_ExecutionPolicy&&, _BidirectionalIterator __first, _BidirectionalIterator __middle,
                          _BidirectionalIterator __last, _Compare __comp, _IsVector __is_vector,
                          /* is_parallel = */ ::std::false_type) noexcept
  {
      __internal::__brick_inplace_merge(__first, __middle, __last, __comp, __is_vector);
  }
  
  template <class _ExecutionPolicy, class _BidirectionalIterator, class _Compare, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, void>
  __pattern_inplace_merge(_ExecutionPolicy&& __exec, _BidirectionalIterator __first, _BidirectionalIterator __middle,
                          _BidirectionalIterator __last, _Compare __comp, _IsVector __is_vector,
                          /*is_parallel=*/::std::true_type)
  {
      if (__first == __last || __first == __middle || __middle == __last)
      {
          return;
      }
      typedef typename ::std::iterator_traits<_BidirectionalIterator>::value_type _Tp;
      auto __n = __last - __first;
      __par_backend::__buffer<_ExecutionPolicy, _Tp> __buf(__n);
      _Tp* __r = __buf.get();
      __internal::__except_handler([&]() {
          auto __move_values = [](_BidirectionalIterator __x, _Tp* __z) {
              __invoke_if_else(::std::is_trivial<_Tp>(), [&]() { *__z = ::std::move(*__x); },
                               [&]() { ::new (::std::addressof(*__z)) _Tp(::std::move(*__x)); });
          };
  
          auto __move_sequences = [](_BidirectionalIterator __first1, _BidirectionalIterator __last1, _Tp* __first2) {
              return __internal::__brick_uninitialized_move(__first1, __last1, __first2, _IsVector());
          };
  
          __par_backend::__parallel_merge(
              ::std::forward<_ExecutionPolicy>(__exec), __first, __middle, __middle, __last, __r, __comp,
              [__n, __move_values, __move_sequences](_BidirectionalIterator __f1, _BidirectionalIterator __l1,
                                                     _BidirectionalIterator __f2, _BidirectionalIterator __l2, _Tp* __f3,
                                                     _Compare __comp) {
                  (__utils::__serial_move_merge(__n))(__f1, __l1, __f2, __l2, __f3, __comp, __move_values, __move_values,
                                                      __move_sequences, __move_sequences);
                  return __f3 + (__l1 - __f1) + (__l2 - __f2);
              });
          __par_backend::__parallel_for(
              ::std::forward<_ExecutionPolicy>(__exec), __r, __r + __n, [__r, __first, __is_vector](_Tp* __i, _Tp* __j) {
                  __brick_move_destroy<_ExecutionPolicy>{}(__i, __j, __first + (__i - __r), __is_vector);
              });
      });
  }
  
  //------------------------------------------------------------------------
  // includes
  //------------------------------------------------------------------------
  
  template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _Compare, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, bool>
  __pattern_includes(_ExecutionPolicy&&, _ForwardIterator1 __first1, _ForwardIterator1 __last1,
                     _ForwardIterator2 __first2, _ForwardIterator2 __last2, _Compare __comp, _IsVector,
                     /*is_parallel=*/::std::false_type) noexcept
  {
      return ::std::includes(__first1, __last1, __first2, __last2, __comp);
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _Compare, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, bool>
  __pattern_includes(_ExecutionPolicy&& __exec, _ForwardIterator1 __first1, _ForwardIterator1 __last1,
                     _ForwardIterator2 __first2, _ForwardIterator2 __last2, _Compare __comp, _IsVector,
                     /*is_parallel=*/::std::true_type)
  {
      if (__first2 == __last2)
          return true;
  
      //optimization; {1} - the first sequence, {2} - the second sequence
      //{1} is empty or size_of{2} > size_of{1}
      if (__first1 == __last1 || __last2 - __first2 > __last1 - __first1 ||
          // {1}:     [**********]     or   [**********]
          // {2}: [***********]                   [***********]
          __comp(*__first2, *__first1) || __comp(*(__last1 - 1), *(__last2 - 1)))
          return false;
  
      __first1 = ::std::lower_bound(__first1, __last1, *__first2, __comp);
      if (__first1 == __last1)
          return false;
  
      if (__last2 - __first2 == 1)
          return !__comp(*__first1, *__first2) && !__comp(*__first2, *__first1);
  
      return __internal::__except_handler([&]() {
          return !__internal::__parallel_or(
              ::std::forward<_ExecutionPolicy>(__exec), __first2, __last2,
              [__first1, __last1, __first2, __last2, &__comp](_ForwardIterator2 __i, _ForwardIterator2 __j) {
                  assert(__j > __i);
                  //assert(__j - __i > 1);
  
                  //1. moving boundaries to "consume" subsequence of equal elements
                  auto __is_equal_sorted = [&__comp](_ForwardIterator2 __a, _ForwardIterator2 __b) -> bool {
                      //enough one call of __comp due to compared couple belongs to one sorted sequience
                      return !__comp(*__a, *__b);
                  };
  
                  //1.1 left bound, case "aaa[aaaxyz...]" - searching "x"
                  if (__i > __first2 && __is_equal_sorted(__i - 1, __i))
                  {
                      //whole subrange continues to have equal elements - return "no op"
                      if (__is_equal_sorted(__i, __j - 1))
                          return false;
  
                      __i = ::std::upper_bound(__i, __last2, *__i, __comp);
                  }
  
                  //1.2 right bound, case "[...aaa]aaaxyz" - searching "x"
                  if (__j < __last2 && __is_equal_sorted(__j - 1, __j))
                      __j = ::std::upper_bound(__j, __last2, *__j, __comp);
  
                  //2. testing is __a subsequence of the second range included into the first range
                  auto __b = ::std::lower_bound(__first1, __last1, *__i, __comp);
  
                  assert(!__comp(*(__last1 - 1), *__b));
                  assert(!__comp(*(__j - 1), *__i));
                  return !::std::includes(__b, __last1, __i, __j, __comp);
              });
      });
  }
  
  constexpr auto __set_algo_cut_off = 1000;
  
  template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _OutputIterator,
            class _Compare, class _IsVector, class _SizeFunction, class _SetOP>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _OutputIterator>
  __parallel_set_op(_ExecutionPolicy&& __exec, _ForwardIterator1 __first1, _ForwardIterator1 __last1,
                    _ForwardIterator2 __first2, _ForwardIterator2 __last2, _OutputIterator __result, _Compare __comp,
                    _SizeFunction __size_func, _SetOP __set_op, _IsVector __is_vector)
  {
      typedef typename ::std::iterator_traits<_ForwardIterator1>::difference_type _DifferenceType;
      typedef typename ::std::iterator_traits<_OutputIterator>::value_type _T;
  
      struct _SetRange
      {
          _DifferenceType __pos, __len, __buf_pos;
          bool
          empty() const
          {
              return __len == 0;
          }
      };
  
      const _DifferenceType __n1 = __last1 - __first1;
      const _DifferenceType __n2 = __last2 - __first2;
  
      __par_backend::__buffer<_ExecutionPolicy, _T> __buf(__size_func(__n1, __n2));
  
      return __internal::__except_handler([&__exec, __n1, __first1, __last1, __first2, __last2, __result, __is_vector,
                                           __comp, __size_func, __set_op, &__buf]() {
          auto __buffer = __buf.get();
          _DifferenceType __m{};
          auto __scan = [=](_DifferenceType, _DifferenceType, const _SetRange& __s) { // Scan
              if (!__s.empty())
                  __brick_move_destroy<_ExecutionPolicy>{}(__buffer + __s.__buf_pos,
                                                           __buffer + (__s.__buf_pos + __s.__len), __result + __s.__pos,
                                                           __is_vector);
          };
          __par_backend::__parallel_strict_scan(
              ::std::forward<_ExecutionPolicy>(__exec), __n1, _SetRange{0, 0, 0}, //-1, 0},
              [=](_DifferenceType __i, _DifferenceType __len) {                   // Reduce
                  //[__b; __e) - a subrange of the first sequence, to reduce
                  _ForwardIterator1 __b = __first1 + __i, __e = __first1 + (__i + __len);
  
                  //try searching for the first element which not equal to *__b
                  if (__b != __first1)
                      __b = ::std::upper_bound(__b, __last1, *__b, __comp);
  
                  //try searching for the first element which not equal to *__e
                  if (__e != __last1)
                      __e = ::std::upper_bound(__e, __last1, *__e, __comp);
  
                  //check is [__b; __e) empty
                  if (__e - __b < 1)
                  {
                      _ForwardIterator2 __bb = __last2;
                      if (__b != __last1)
                          __bb = ::std::lower_bound(__first2, __last2, *__b, __comp);
  
                      const _DifferenceType __buf_pos = __size_func((__b - __first1), (__bb - __first2));
                      return _SetRange{0, 0, __buf_pos};
                  }
  
                  //try searching for "corresponding" subrange [__bb; __ee) in the second sequence
                  _ForwardIterator2 __bb = __first2;
                  if (__b != __first1)
                      __bb = ::std::lower_bound(__first2, __last2, *__b, __comp);
  
                  _ForwardIterator2 __ee = __last2;
                  if (__e != __last1)
                      __ee = ::std::lower_bound(__bb, __last2, *__e, __comp);
  
                  const _DifferenceType __buf_pos = __size_func((__b - __first1), (__bb - __first2));
                  auto __buffer_b = __buffer + __buf_pos;
                  auto __res = __set_op(__b, __e, __bb, __ee, __buffer_b, __comp);
  
                  return _SetRange{0, __res - __buffer_b, __buf_pos};
              },
              [](const _SetRange& __a, const _SetRange& __b) { // Combine
                  if (__b.__buf_pos > __a.__buf_pos || ((__b.__buf_pos == __a.__buf_pos) && !__b.empty()))
                      return _SetRange{__a.__pos + __a.__len + __b.__pos, __b.__len, __b.__buf_pos};
                  return _SetRange{__b.__pos + __b.__len + __a.__pos, __a.__len, __a.__buf_pos};
              },
              __scan,                                     // Scan
              [&__m, &__scan](const _SetRange& __total) { // Apex
                  //final scan
                  __scan(0, 0, __total);
                  __m = __total.__pos + __total.__len;
              });
          return __result + __m;
      });
  }
  
  //a shared parallel pattern for '__pattern_set_union' and '__pattern_set_symmetric_difference'
  template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _OutputIterator,
            class _Compare, class _SetUnionOp, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _OutputIterator>
  __parallel_set_union_op(_ExecutionPolicy&& __exec, _ForwardIterator1 __first1, _ForwardIterator1 __last1,
                          _ForwardIterator2 __first2, _ForwardIterator2 __last2, _OutputIterator __result,
                          _Compare __comp, _SetUnionOp __set_union_op, _IsVector __is_vector)
  {
      typedef typename ::std::iterator_traits<_ForwardIterator1>::difference_type _DifferenceType;
  
      const auto __n1 = __last1 - __first1;
      const auto __n2 = __last2 - __first2;
  
      __brick_copy<_ExecutionPolicy> __copy_range{};
  
      // {1} {}: parallel copying just first sequence
      if (__n2 == 0)
          return __pattern_walk2_brick(::std::forward<_ExecutionPolicy>(__exec), __first1, __last1, __result,
                                       __copy_range, ::std::true_type());
  
      // {} {2}: parallel copying justmake  second sequence
      if (__n1 == 0)
          return __pattern_walk2_brick(::std::forward<_ExecutionPolicy>(__exec), __first2, __last2, __result,
                                       __copy_range, ::std::true_type());
  
      // testing  whether the sequences are intersected
      _ForwardIterator1 __left_bound_seq_1 = ::std::lower_bound(__first1, __last1, *__first2, __comp);
  
      if (__left_bound_seq_1 == __last1)
      {
          //{1} < {2}: seq2 is wholly greater than seq1, so, do parallel copying seq1 and seq2
          __par_backend::__parallel_invoke(::std::forward<_ExecutionPolicy>(__exec),
                                           [=] {
                                               __pattern_walk2_brick(::std::forward<_ExecutionPolicy>(__exec), __first1,
                                                                     __last1, __result, __copy_range, ::std::true_type());
                                           },
                                           [=] {
                                               __pattern_walk2_brick(::std::forward<_ExecutionPolicy>(__exec), __first2,
                                                                     __last2, __result + __n1, __copy_range,
                                                                     ::std::true_type());
                                           });
          return __result + __n1 + __n2;
      }
  
      // testing  whether the sequences are intersected
      _ForwardIterator2 __left_bound_seq_2 = ::std::lower_bound(__first2, __last2, *__first1, __comp);
  
      if (__left_bound_seq_2 == __last2)
      {
          //{2} < {1}: seq2 is wholly greater than seq1, so, do parallel copying seq1 and seq2
          __par_backend::__parallel_invoke(::std::forward<_ExecutionPolicy>(__exec),
                                           [=] {
                                               __pattern_walk2_brick(::std::forward<_ExecutionPolicy>(__exec), __first2,
                                                                     __last2, __result, __copy_range, ::std::true_type());
                                           },
                                           [=] {
                                               __pattern_walk2_brick(::std::forward<_ExecutionPolicy>(__exec), __first1,
                                                                     __last1, __result + __n2, __copy_range,
                                                                     ::std::true_type());
                                           });
          return __result + __n1 + __n2;
      }
  
      const auto __m1 = __left_bound_seq_1 - __first1;
      if (__m1 > __set_algo_cut_off)
      {
          auto __res_or = __result;
          __result += __m1; //we know proper offset due to [first1; left_bound_seq_1) < [first2; last2)
          __par_backend::__parallel_invoke(
              ::std::forward<_ExecutionPolicy>(__exec),
              //do parallel copying of [first1; left_bound_seq_1)
              [=] {
                  __pattern_walk2_brick(::std::forward<_ExecutionPolicy>(__exec), __first1, __left_bound_seq_1, __res_or,
                                        __copy_range, ::std::true_type());
              },
              [=, &__result] {
                  __result = __parallel_set_op(::std::forward<_ExecutionPolicy>(__exec), __left_bound_seq_1, __last1,
                                               __first2, __last2, __result, __comp,
                                               [](_DifferenceType __n, _DifferenceType __m) { return __n + __m; },
                                               __set_union_op, __is_vector);
              });
          return __result;
      }
  
      const auto __m2 = __left_bound_seq_2 - __first2;
      assert(__m1 == 0 || __m2 == 0);
      if (__m2 > __set_algo_cut_off)
      {
          auto __res_or = __result;
          __result += __m2; //we know proper offset due to [first2; left_bound_seq_2) < [first1; last1)
          __par_backend::__parallel_invoke(
              ::std::forward<_ExecutionPolicy>(__exec),
              //do parallel copying of [first2; left_bound_seq_2)
              [=] {
                  __pattern_walk2_brick(::std::forward<_ExecutionPolicy>(__exec), __first2, __left_bound_seq_2, __res_or,
                                        __copy_range, ::std::true_type());
              },
              [=, &__result] {
                  __result = __parallel_set_op(::std::forward<_ExecutionPolicy>(__exec), __first1, __last1,
                                               __left_bound_seq_2, __last2, __result, __comp,
                                               [](_DifferenceType __n, _DifferenceType __m) { return __n + __m; },
                                               __set_union_op, __is_vector);
              });
          return __result;
      }
  
      return __parallel_set_op(::std::forward<_ExecutionPolicy>(__exec), __first1, __last1, __first2, __last2, __result,
                               __comp, [](_DifferenceType __n, _DifferenceType __m) { return __n + __m; }, __set_union_op,
                               __is_vector);
  }
  
  //------------------------------------------------------------------------
  // set_union
  //------------------------------------------------------------------------
  
  template <class _ForwardIterator1, class _ForwardIterator2, class _OutputIterator, class _Compare>
  _OutputIterator
  __brick_set_union(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2,
                    _ForwardIterator2 __last2, _OutputIterator __result, _Compare __comp,
                    /*__is_vector=*/::std::false_type) noexcept
  {
      return ::std::set_union(__first1, __last1, __first2, __last2, __result, __comp);
  }
  
  template <typename _IsVector>
  struct __BrickCopyConstruct
  {
      template <typename _ForwardIterator, typename _OutputIterator>
      _OutputIterator
      operator()(_ForwardIterator __first, _ForwardIterator __last, _OutputIterator __result)
      {
          return __brick_uninitialized_copy(__first, __last, __result, _IsVector());
      }
  };
  
  template <class _ForwardIterator1, class _ForwardIterator2, class _OutputIterator, class _Compare>
  _OutputIterator
  __brick_set_union(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2,
                    _ForwardIterator2 __last2, _OutputIterator __result, _Compare __comp,
                    /*__is_vector=*/::std::true_type) noexcept
  {
      _PSTL_PRAGMA_MESSAGE("Vectorized algorithm unimplemented, redirected to serial");
      return ::std::set_union(__first1, __last1, __first2, __last2, __result, __comp);
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _OutputIterator,
            class _Compare, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _OutputIterator>
  __pattern_set_union(_ExecutionPolicy&&, _ForwardIterator1 __first1, _ForwardIterator1 __last1,
                      _ForwardIterator2 __first2, _ForwardIterator2 __last2, _OutputIterator __result, _Compare __comp,
                      _IsVector __is_vector,
                      /*is_parallel=*/::std::false_type) noexcept
  {
      return __internal::__brick_set_union(__first1, __last1, __first2, __last2, __result, __comp, __is_vector);
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _OutputIterator,
            class _Compare, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _OutputIterator>
  __pattern_set_union(_ExecutionPolicy&& __exec, _ForwardIterator1 __first1, _ForwardIterator1 __last1,
                      _ForwardIterator2 __first2, _ForwardIterator2 __last2, _OutputIterator __result, _Compare __comp,
                      _IsVector __is_vector, /*__is_parallel=*/::std::true_type)
  {
  
      const auto __n1 = __last1 - __first1;
      const auto __n2 = __last2 - __first2;
  
      // use serial algorithm
      if (__n1 + __n2 <= __set_algo_cut_off)
          return ::std::set_union(__first1, __last1, __first2, __last2, __result, __comp);
  
      typedef typename ::std::iterator_traits<_OutputIterator>::value_type _Tp;
      return __parallel_set_union_op(
          ::std::forward<_ExecutionPolicy>(__exec), __first1, __last1, __first2, __last2, __result, __comp,
          [](_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2, _ForwardIterator2 __last2,
             _Tp* __result, _Compare __comp) {
              return oneapi::dpl::__utils::__set_union_construct(__first1, __last1, __first2, __last2, __result, __comp,
                                                                 __BrickCopyConstruct<_IsVector>());
          },
          __is_vector);
  }
  
  //------------------------------------------------------------------------
  // set_intersection
  //------------------------------------------------------------------------
  
  template <class _ForwardIterator1, class _ForwardIterator2, class _OutputIterator, class _Compare>
  _OutputIterator
  __brick_set_intersection(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2,
                           _ForwardIterator2 __last2, _OutputIterator __result, _Compare __comp,
                           /*__is_vector=*/::std::false_type) noexcept
  {
      return ::std::set_intersection(__first1, __last1, __first2, __last2, __result, __comp);
  }
  
  template <class _ForwardIterator1, class _ForwardIterator2, class _OutputIterator, class _Compare>
  _OutputIterator
  __brick_set_intersection(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2,
                           _ForwardIterator2 __last2, _OutputIterator __result, _Compare __comp,
                           /*__is_vector=*/::std::true_type) noexcept
  {
      _PSTL_PRAGMA_MESSAGE("Vectorized algorithm unimplemented, redirected to serial");
      return ::std::set_intersection(__first1, __last1, __first2, __last2, __result, __comp);
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _OutputIterator,
            class _Compare, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _OutputIterator>
  __pattern_set_intersection(_ExecutionPolicy&&, _ForwardIterator1 __first1, _ForwardIterator1 __last1,
                             _ForwardIterator2 __first2, _ForwardIterator2 __last2, _OutputIterator __result,
                             _Compare __comp, _IsVector __is_vector, /*is_parallel=*/::std::false_type) noexcept
  {
      return __internal::__brick_set_intersection(__first1, __last1, __first2, __last2, __result, __comp, __is_vector);
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _OutputIterator,
            class _Compare, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _OutputIterator>
  __pattern_set_intersection(_ExecutionPolicy&& __exec, _ForwardIterator1 __first1, _ForwardIterator1 __last1,
                             _ForwardIterator2 __first2, _ForwardIterator2 __last2, _OutputIterator __result,
                             _Compare __comp, _IsVector __is_vector, /*is_parallel=*/::std::true_type)
  {
      typedef typename ::std::iterator_traits<_OutputIterator>::value_type _T;
      typedef typename ::std::iterator_traits<_ForwardIterator1>::difference_type _DifferenceType;
  
      const auto __n1 = __last1 - __first1;
      const auto __n2 = __last2 - __first2;
  
      // intersection is empty
      if (__n1 == 0 || __n2 == 0)
          return __result;
  
      // testing  whether the sequences are intersected
      _ForwardIterator1 __left_bound_seq_1 = ::std::lower_bound(__first1, __last1, *__first2, __comp);
      //{1} < {2}: seq 2 is wholly greater than seq 1, so, the intersection is empty
      if (__left_bound_seq_1 == __last1)
          return __result;
  
      // testing  whether the sequences are intersected
      _ForwardIterator2 __left_bound_seq_2 = ::std::lower_bound(__first2, __last2, *__first1, __comp);
      //{2} < {1}: seq 1 is wholly greater than seq 2, so, the intersection is empty
      if (__left_bound_seq_2 == __last2)
          return __result;
  
      const auto __m1 = __last1 - __left_bound_seq_1 + __n2;
      if (__m1 > __set_algo_cut_off)
      {
          //we know proper offset due to [first1; left_bound_seq_1) < [first2; last2)
          return __internal::__parallel_set_op(
              ::std::forward<_ExecutionPolicy>(__exec), __left_bound_seq_1, __last1, __first2, __last2, __result, __comp,
              [](_DifferenceType __n, _DifferenceType __m) { return ::std::min(__n, __m); },
              [](_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2,
                 _ForwardIterator2 __last2, _T* __result, _Compare __comp) {
                  return oneapi::dpl::__utils::__set_intersection_construct(__first1, __last1, __first2, __last2,
                                                                            __result, __comp);
              },
              __is_vector);
      }
  
      const auto __m2 = __last2 - __left_bound_seq_2 + __n1;
      if (__m2 > __set_algo_cut_off)
      {
          //we know proper offset due to [first2; left_bound_seq_2) < [first1; last1)
          __result = __internal::__parallel_set_op(
              ::std::forward<_ExecutionPolicy>(__exec), __first1, __last1, __left_bound_seq_2, __last2, __result, __comp,
              [](_DifferenceType __n, _DifferenceType __m) { return ::std::min(__n, __m); },
              [](_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2,
                 _ForwardIterator2 __last2, _T* __result, _Compare __comp) {
                  return oneapi::dpl::__utils::__set_intersection_construct(__first2, __last2, __first1, __last1,
                                                                            __result, __comp);
              },
              __is_vector);
          return __result;
      }
  
      // [left_bound_seq_1; last1) and [left_bound_seq_2; last2) - use serial algorithm
      return ::std::set_intersection(__left_bound_seq_1, __last1, __left_bound_seq_2, __last2, __result, __comp);
  }
  
  //------------------------------------------------------------------------
  // set_difference
  //------------------------------------------------------------------------
  
  template <class _ForwardIterator1, class _ForwardIterator2, class _OutputIterator, class _Compare>
  _OutputIterator
  __brick_set_difference(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2,
                         _ForwardIterator2 __last2, _OutputIterator __result, _Compare __comp,
                         /*__is_vector=*/::std::false_type) noexcept
  {
      return ::std::set_difference(__first1, __last1, __first2, __last2, __result, __comp);
  }
  
  template <class _ForwardIterator1, class _ForwardIterator2, class _OutputIterator, class _Compare>
  _OutputIterator
  __brick_set_difference(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2,
                         _ForwardIterator2 __last2, _OutputIterator __result, _Compare __comp,
                         /*__is_vector=*/::std::true_type) noexcept
  {
      _PSTL_PRAGMA_MESSAGE("Vectorized algorithm unimplemented, redirected to serial");
      return ::std::set_difference(__first1, __last1, __first2, __last2, __result, __comp);
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _OutputIterator,
            class _Compare, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _OutputIterator>
  __pattern_set_difference(_ExecutionPolicy&&, _ForwardIterator1 __first1, _ForwardIterator1 __last1,
                           _ForwardIterator2 __first2, _ForwardIterator2 __last2, _OutputIterator __result,
                           _Compare __comp, _IsVector __is_vector, /*is_parallel=*/::std::false_type) noexcept
  {
      return __internal::__brick_set_difference(__first1, __last1, __first2, __last2, __result, __comp, __is_vector);
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _OutputIterator,
            class _Compare, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _OutputIterator>
  __pattern_set_difference(_ExecutionPolicy&& __exec, _ForwardIterator1 __first1, _ForwardIterator1 __last1,
                           _ForwardIterator2 __first2, _ForwardIterator2 __last2, _OutputIterator __result,
                           _Compare __comp, _IsVector __is_vector, /*is_parallel=*/::std::true_type)
  {
      typedef typename ::std::iterator_traits<_OutputIterator>::value_type _T;
      typedef typename ::std::iterator_traits<_ForwardIterator1>::difference_type _DifferenceType;
  
      const auto __n1 = __last1 - __first1;
      const auto __n2 = __last2 - __first2;
  
      // {} \ {2}: the difference is empty
      if (__n1 == 0)
          return __result;
  
      // {1} \ {}: parallel copying just first sequence
      if (__n2 == 0)
          return __pattern_walk2_brick(::std::forward<_ExecutionPolicy>(__exec), __first1, __last1, __result,
                                       __brick_copy<_ExecutionPolicy>{}, ::std::true_type());
  
      // testing  whether the sequences are intersected
      _ForwardIterator1 __left_bound_seq_1 = ::std::lower_bound(__first1, __last1, *__first2, __comp);
      //{1} < {2}: seq 2 is wholly greater than seq 1, so, parallel copying just first sequence
      if (__left_bound_seq_1 == __last1)
          return __pattern_walk2_brick(::std::forward<_ExecutionPolicy>(__exec), __first1, __last1, __result,
                                       __brick_copy<_ExecutionPolicy>{}, ::std::true_type());
  
      // testing  whether the sequences are intersected
      _ForwardIterator2 __left_bound_seq_2 = ::std::lower_bound(__first2, __last2, *__first1, __comp);
      //{2} < {1}: seq 1 is wholly greater than seq 2, so, parallel copying just first sequence
      if (__left_bound_seq_2 == __last2)
          return __pattern_walk2_brick(::std::forward<_ExecutionPolicy>(__exec), __first1, __last1, __result,
                                       __brick_copy<_ExecutionPolicy>{}, ::std::true_type());
  
      if (__n1 + __n2 > __set_algo_cut_off)
          return __parallel_set_op(::std::forward<_ExecutionPolicy>(__exec), __first1, __last1, __first2, __last2,
                                   __result, __comp, [](_DifferenceType __n, _DifferenceType) { return __n; },
                                   [](_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2,
                                      _ForwardIterator2 __last2, _T* __result, _Compare __comp) {
                                       return oneapi::dpl::__utils::__set_difference_construct(
                                           __first1, __last1, __first2, __last2, __result, __comp,
                                           __BrickCopyConstruct<_IsVector>());
                                   },
                                   __is_vector);
  
      // use serial algorithm
      return ::std::set_difference(__first1, __last1, __first2, __last2, __result, __comp);
  }
  
  //------------------------------------------------------------------------
  // set_symmetric_difference
  //------------------------------------------------------------------------
  
  template <class _ForwardIterator1, class _ForwardIterator2, class _OutputIterator, class _Compare>
  _OutputIterator
  __brick_set_symmetric_difference(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2,
                                   _ForwardIterator2 __last2, _OutputIterator __result, _Compare __comp,
                                   /*__is_vector=*/::std::false_type) noexcept
  {
      return ::std::set_symmetric_difference(__first1, __last1, __first2, __last2, __result, __comp);
  }
  
  template <class _ForwardIterator1, class _ForwardIterator2, class _OutputIterator, class _Compare>
  _OutputIterator
  __brick_set_symmetric_difference(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2,
                                   _ForwardIterator2 __last2, _OutputIterator __result, _Compare __comp,
                                   /*__is_vector=*/::std::true_type) noexcept
  {
      _PSTL_PRAGMA_MESSAGE("Vectorized algorithm unimplemented, redirected to serial");
      return ::std::set_symmetric_difference(__first1, __last1, __first2, __last2, __result, __comp);
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _OutputIterator,
            class _Compare, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _OutputIterator>
  __pattern_set_symmetric_difference(_ExecutionPolicy&&, _ForwardIterator1 __first1, _ForwardIterator1 __last1,
                                     _ForwardIterator2 __first2, _ForwardIterator2 __last2, _OutputIterator __result,
                                     _Compare __comp, _IsVector __is_vector, /*is_parallel=*/::std::false_type) noexcept
  {
      return __internal::__brick_set_symmetric_difference(__first1, __last1, __first2, __last2, __result, __comp,
                                                          __is_vector);
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _OutputIterator,
            class _Compare, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _OutputIterator>
  __pattern_set_symmetric_difference(_ExecutionPolicy&& __exec, _ForwardIterator1 __first1, _ForwardIterator1 __last1,
                                     _ForwardIterator2 __first2, _ForwardIterator2 __last2, _OutputIterator __result,
                                     _Compare __comp, _IsVector __is_vector, /*is_parallel=*/::std::true_type)
  {
  
      const auto __n1 = __last1 - __first1;
      const auto __n2 = __last2 - __first2;
  
      // use serial algorithm
      if (__n1 + __n2 <= __set_algo_cut_off)
          return ::std::set_symmetric_difference(__first1, __last1, __first2, __last2, __result, __comp);
  
      typedef typename ::std::iterator_traits<_OutputIterator>::value_type _T;
      return __internal::__parallel_set_union_op(
          ::std::forward<_ExecutionPolicy>(__exec), __first1, __last1, __first2, __last2, __result, __comp,
          [](_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2, _ForwardIterator2 __last2,
             _T* __result, _Compare __comp) {
              return oneapi::dpl::__utils::__set_symmetric_difference_construct(
                  __first1, __last1, __first2, __last2, __result, __comp, __BrickCopyConstruct<_IsVector>());
          },
          __is_vector);
  }
  
  //------------------------------------------------------------------------
  // is_heap_until
  //------------------------------------------------------------------------
  
  template <class _RandomAccessIterator, class _Compare>
  _RandomAccessIterator
  __brick_is_heap_until(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp,
                        /* __is_vector = */ ::std::false_type) noexcept
  {
      return ::std::is_heap_until(__first, __last, __comp);
  }
  
  template <class _RandomAccessIterator, class _Compare>
  _RandomAccessIterator
  __brick_is_heap_until(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp,
                        /* __is_vector = */ ::std::true_type) noexcept
  {
      typedef typename ::std::iterator_traits<_RandomAccessIterator>::difference_type _SizeType;
      return __unseq_backend::__simd_first(
          __first, _SizeType(0), __last - __first,
          [&__comp](_RandomAccessIterator __it, _SizeType __i) { return __comp(__it[(__i - 1) / 2], __it[__i]); });
  }
  
  template <class _ExecutionPolicy, class _RandomAccessIterator, class _Compare, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _RandomAccessIterator>
  __pattern_is_heap_until(_ExecutionPolicy&&, _RandomAccessIterator __first, _RandomAccessIterator __last,
                          _Compare __comp, _IsVector __is_vector, /* is_parallel = */ ::std::false_type) noexcept
  {
      return __internal::__brick_is_heap_until(__first, __last, __comp, __is_vector);
  }
  
  template <class _RandomAccessIterator, class _DifferenceType, class _Compare>
  _RandomAccessIterator
  __is_heap_until_local(_RandomAccessIterator __first, _DifferenceType __begin, _DifferenceType __end, _Compare __comp,
                        /* __is_vector = */ ::std::false_type) noexcept
  {
      _DifferenceType __i = __begin;
      for (; __i < __end; ++__i)
          if (__comp(__first[(__i - 1) / 2], __first[__i]))
              break;
      return __first + __i;
  }
  
  template <class _RandomAccessIterator, class _DifferenceType, class _Compare>
  _RandomAccessIterator
  __is_heap_until_local(_RandomAccessIterator __first, _DifferenceType __begin, _DifferenceType __end, _Compare __comp,
                        /* __is_vector = */ ::std::true_type) noexcept
  {
      return __unseq_backend::__simd_first(
          __first, __begin, __end,
          [&__comp](_RandomAccessIterator __it, _DifferenceType __i) { return __comp(__it[(__i - 1) / 2], __it[__i]); });
  }
  
  template <class _ExecutionPolicy, class _RandomAccessIterator, class _Compare, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _RandomAccessIterator>
  __pattern_is_heap_until(_ExecutionPolicy&& __exec, _RandomAccessIterator __first, _RandomAccessIterator __last,
                          _Compare __comp, _IsVector __is_vector, /* is_parallel = */ ::std::true_type)
  {
      return __internal::__except_handler([&]() {
          return __parallel_find(::std::forward<_ExecutionPolicy>(__exec), __first, __last,
                                 [__first, __comp, __is_vector](_RandomAccessIterator __i, _RandomAccessIterator __j) {
                                     return __internal::__is_heap_until_local(__first, __i - __first, __j - __first,
                                                                              __comp, __is_vector);
                                 },
                                 ::std::true_type{});
      });
  }
  
  //------------------------------------------------------------------------
  // is_heap
  //------------------------------------------------------------------------
  
  template <class _RandomAccessIterator, class _Compare>
  bool
  __brick_is_heap(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp,
                  /* __is_vector = */ ::std::false_type) noexcept
  {
      return ::std::is_heap(__first, __last, __comp);
  }
  
  template <class _RandomAccessIterator, class _Compare>
  bool
  __brick_is_heap(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp,
                  /* __is_vector = */ ::std::true_type) noexcept
  {
      return !__unseq_backend::__simd_or_iter(__first, __last - __first, [__first, &__comp](_RandomAccessIterator __it) {
          return __comp(*(__first + (__it - __first - 1) / 2), *__it);
      });
  }
  
  template <class _RandomAccessIterator, class _DifferenceType, class _Compare>
  bool
  __is_heap_local(_RandomAccessIterator __first, _DifferenceType __begin, _DifferenceType __end, _Compare __comp,
                  /* __is_vector = */ ::std::false_type) noexcept
  {
      return __internal::__is_heap_until_local(__first, __begin, __end, __comp, ::std::false_type{}) == __first + __end;
  }
  
  template <class _RandomAccessIterator, class _DifferenceType, class _Compare>
  bool
  __is_heap_local(_RandomAccessIterator __first, _DifferenceType __begin, _DifferenceType __end, _Compare __comp,
                  /* __is_vector = */ ::std::true_type) noexcept
  {
      return !__unseq_backend::__simd_or_iter(__first + __begin, __end - __begin,
                                              [__first, &__comp](_RandomAccessIterator __it) {
                                                  return __comp(*(__first + (__it - __first - 1) / 2), *__it);
                                              });
  }
  
  template <class _ExecutionPolicy, class _RandomAccessIterator, class _Compare, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, bool>
  __pattern_is_heap(_ExecutionPolicy&&, _RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp,
                    _IsVector __is_vector, /* is_parallel = */ ::std::false_type) noexcept
  {
      return __internal::__brick_is_heap(__first, __last, __comp, __is_vector);
  }
  
  template <class _ExecutionPolicy, class _RandomAccessIterator, class _Compare, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, bool>
  __pattern_is_heap(_ExecutionPolicy&& __exec, _RandomAccessIterator __first, _RandomAccessIterator __last,
                    _Compare __comp, _IsVector __is_vector, /* is_parallel = */ ::std::true_type)
  {
      return __internal::__except_handler([&]() {
          return !__parallel_or(::std::forward<_ExecutionPolicy>(__exec), __first, __last,
                                [__first, __comp, __is_vector](_RandomAccessIterator __i, _RandomAccessIterator __j) {
                                    return !__internal::__is_heap_local(__first, __i - __first, __j - __first, __comp,
                                                                        __is_vector);
                                });
      });
  }
  
  //------------------------------------------------------------------------
  // min_element
  //------------------------------------------------------------------------
  
  template <typename _ForwardIterator, typename _Compare>
  _ForwardIterator
  __brick_min_element(_ForwardIterator __first, _ForwardIterator __last, _Compare __comp,
                      /* __is_vector = */ ::std::false_type) noexcept
  {
      return ::std::min_element(__first, __last, __comp);
  }
  
  template <typename _ForwardIterator, typename _Compare>
  _ForwardIterator
  __brick_min_element(_ForwardIterator __first, _ForwardIterator __last, _Compare __comp,
                      /* __is_vector = */ ::std::true_type) noexcept
  {
  #if (_PSTL_UDR_PRESENT || _ONEDPL_UDR_PRESENT)
      return __unseq_backend::__simd_min_element(__first, __last - __first, __comp);
  #else
      return ::std::min_element(__first, __last, __comp);
  #endif
  }
  
  template <typename _ExecutionPolicy, typename _ForwardIterator, typename _Compare, typename _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _ForwardIterator>
  __pattern_min_element(_ExecutionPolicy&&, _ForwardIterator __first, _ForwardIterator __last, _Compare __comp,
                        _IsVector __is_vector, /* is_parallel = */ ::std::false_type) noexcept
  {
      return __internal::__brick_min_element(__first, __last, __comp, __is_vector);
  }
  
  template <typename _ExecutionPolicy, typename _RandomAccessIterator, typename _Compare, typename _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _RandomAccessIterator>
  __pattern_min_element(_ExecutionPolicy&& __exec, _RandomAccessIterator __first, _RandomAccessIterator __last,
                        _Compare __comp, _IsVector __is_vector, /* is_parallel = */ ::std::true_type)
  {
      // a trivial case pre-check
      if (__last - __first < 2)
          return __first;
  
      return __internal::__except_handler([&]() {
          return __par_backend::__parallel_reduce(
              ::std::forward<_ExecutionPolicy>(__exec), __first, __last, /*identity*/ __last,
              [=](_RandomAccessIterator __begin, _RandomAccessIterator __end,
                  _RandomAccessIterator __init) -> _RandomAccessIterator {
                  const _RandomAccessIterator __subresult =
                      __internal::__brick_min_element(__begin, __end, __comp, __is_vector);
                  return __init == __last ? __subresult
                                          : __internal::__cmp_iterators_by_values(__init, __subresult, __comp,
                                                                                  oneapi::dpl::__internal::__pstl_less());
              },
              [=](_RandomAccessIterator __it1, _RandomAccessIterator __it2) -> _RandomAccessIterator {
                  if (__it1 == __last)
                      return __it2;
                  if (__it2 == __last)
                      return __it1;
                  return __internal::__cmp_iterators_by_values(__it1, __it2, __comp,
                                                               oneapi::dpl::__internal::__pstl_less());
              });
      });
  }
  
  //------------------------------------------------------------------------
  // minmax_element
  //------------------------------------------------------------------------
  
  template <typename _ForwardIterator, typename _Compare>
  ::std::pair<_ForwardIterator, _ForwardIterator>
  __brick_minmax_element(_ForwardIterator __first, _ForwardIterator __last, _Compare __comp,
                         /* __is_vector = */ ::std::false_type) noexcept
  {
      return ::std::minmax_element(__first, __last, __comp);
  }
  
  template <typename _ForwardIterator, typename _Compare>
  ::std::pair<_ForwardIterator, _ForwardIterator>
  __brick_minmax_element(_ForwardIterator __first, _ForwardIterator __last, _Compare __comp,
                         /* __is_vector = */ ::std::true_type) noexcept
  {
  #if (_PSTL_UDR_PRESENT || _ONEDPL_UDR_PRESENT)
      return __unseq_backend::__simd_minmax_element(__first, __last - __first, __comp);
  #else
      return ::std::minmax_element(__first, __last, __comp);
  #endif
  }
  
  template <typename _ExecutionPolicy, typename _ForwardIterator, typename _Compare, typename _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy,
                                                             ::std::pair<_ForwardIterator, _ForwardIterator>>
  __pattern_minmax_element(_ExecutionPolicy&&, _ForwardIterator __first, _ForwardIterator __last, _Compare __comp,
                           _IsVector __is_vector, /* is_parallel = */ ::std::false_type) noexcept
  {
      return __internal::__brick_minmax_element(__first, __last, __comp, __is_vector);
  }
  
  template <typename _ExecutionPolicy, typename _ForwardIterator, typename _Compare, typename _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy,
                                                             ::std::pair<_ForwardIterator, _ForwardIterator>>
  __pattern_minmax_element(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last, _Compare __comp,
                           _IsVector __is_vector, /* is_parallel = */ ::std::true_type)
  {
      // a trivial case pre-check
      if (__last - __first < 2)
          return ::std::make_pair(__first, __first);
  
      return __internal::__except_handler([&]() {
          typedef ::std::pair<_ForwardIterator, _ForwardIterator> _Result;
  
          return __par_backend::__parallel_reduce(
              ::std::forward<_ExecutionPolicy>(__exec), __first, __last,
              /*identity*/ ::std::make_pair(__last, __last),
              [=, &__comp](_ForwardIterator __begin, _ForwardIterator __end, _Result __init) -> _Result {
                  const _Result __subresult = __internal::__brick_minmax_element(__begin, __end, __comp, __is_vector);
                  if (__init.first == __last) // = identity
                      return __subresult;
                  return ::std::make_pair(
                      __internal::__cmp_iterators_by_values(__init.first, __subresult.first, __comp,
                                                            oneapi::dpl::__internal::__pstl_less()),
                      __internal::__cmp_iterators_by_values(__init.second, __subresult.second,
                                                            oneapi::dpl::__internal::__reorder_pred<_Compare>(__comp),
                                                            oneapi::dpl::__internal::__pstl_greater()));
              },
              [=, &__comp](_Result __p1, _Result __p2) -> _Result {
                  if (__p1.first == __last)
                      return __p2;
                  if (__p2.first == __last)
                      return __p1;
                  return ::std::make_pair(
                      __internal::__cmp_iterators_by_values(__p1.first, __p2.first, __comp,
                                                            oneapi::dpl::__internal::__pstl_less()),
                      __internal::__cmp_iterators_by_values(__p1.second, __p2.second,
                                                            oneapi::dpl::__internal::__reorder_pred<_Compare>(__comp),
                                                            oneapi::dpl::__internal::__pstl_greater()));
              });
      });
  }
  
  //------------------------------------------------------------------------
  // mismatch
  //------------------------------------------------------------------------
  template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
  ::std::pair<_ForwardIterator1, _ForwardIterator2>
  __mismatch_serial(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2,
                    _ForwardIterator2 __last2, _BinaryPredicate __pred)
  {
  #if (_PSTL_CPP14_2RANGE_MISMATCH_EQUAL_PRESENT || _ONEDPL_CPP14_2RANGE_MISMATCH_EQUAL_PRESENT)
      return ::std::mismatch(__first1, __last1, __first2, __last2, __pred);
  #else
      for (; __first1 != __last1 && __first2 != __last2 && __pred(*__first1, *__first2); ++__first1, ++__first2)
      {
      }
      return ::std::make_pair(__first1, __first2);
  #endif
  }
  
  template <class _ForwardIterator1, class _ForwardIterator2, class _Predicate>
  ::std::pair<_ForwardIterator1, _ForwardIterator2>
  __brick_mismatch(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2,
                   _ForwardIterator2 __last2, _Predicate __pred, /* __is_vector = */ ::std::false_type) noexcept
  {
      return __mismatch_serial(__first1, __last1, __first2, __last2, __pred);
  }
  
  template <class _ForwardIterator1, class _ForwardIterator2, class _Predicate>
  ::std::pair<_ForwardIterator1, _ForwardIterator2>
  __brick_mismatch(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2,
                   _ForwardIterator2 __last2, _Predicate __pred, /* __is_vector = */ ::std::true_type) noexcept
  {
      auto __n = ::std::min(__last1 - __first1, __last2 - __first2);
      return __unseq_backend::__simd_first(__first1, __n, __first2, __not_pred<_Predicate&>(__pred));
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _Predicate, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy,
                                                             ::std::pair<_ForwardIterator1, _ForwardIterator2>>
  __pattern_mismatch(_ExecutionPolicy&&, _ForwardIterator1 __first1, _ForwardIterator1 __last1,
                     _ForwardIterator2 __first2, _ForwardIterator2 __last2, _Predicate __pred, _IsVector __is_vector,
                     /* is_parallel = */ ::std::false_type) noexcept
  {
      return __internal::__brick_mismatch(__first1, __last1, __first2, __last2, __pred, __is_vector);
  }
  
  template <class _ExecutionPolicy, class _RandomAccessIterator1, class _RandomAccessIterator2, class _Predicate,
            class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy,
                                                             ::std::pair<_RandomAccessIterator1, _RandomAccessIterator2>>
  __pattern_mismatch(_ExecutionPolicy&& __exec, _RandomAccessIterator1 __first1, _RandomAccessIterator1 __last1,
                     _RandomAccessIterator2 __first2, _RandomAccessIterator2 __last2, _Predicate __pred,
                     _IsVector __is_vector, /* is_parallel = */ ::std::true_type)
  {
      return __internal::__except_handler([&]() {
          auto __n = ::std::min(__last1 - __first1, __last2 - __first2);
          auto __result = __internal::__parallel_find(
              ::std::forward<_ExecutionPolicy>(__exec), __first1, __first1 + __n,
              [__first1, __first2, __pred, __is_vector](_RandomAccessIterator1 __i, _RandomAccessIterator1 __j) {
                  return __internal::__brick_mismatch(__i, __j, __first2 + (__i - __first1), __first2 + (__j - __first1),
                                                      __pred, __is_vector)
                      .first;
              },
              ::std::true_type{});
          return ::std::make_pair(__result, __first2 + (__result - __first1));
      });
  }
  
  //------------------------------------------------------------------------
  // lexicographical_compare
  //------------------------------------------------------------------------
  
  template <class _ForwardIterator1, class _ForwardIterator2, class _Compare>
  bool
  __brick_lexicographical_compare(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2,
                                  _ForwardIterator2 __last2, _Compare __comp,
                                  /* __is_vector = */ ::std::false_type) noexcept
  {
      return ::std::lexicographical_compare(__first1, __last1, __first2, __last2, __comp);
  }
  
  template <class _ForwardIterator1, class _ForwardIterator2, class _Compare>
  bool
  __brick_lexicographical_compare(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2,
                                  _ForwardIterator2 __last2, _Compare __comp,
                                  /* __is_vector = */ ::std::true_type) noexcept
  {
      if (__first2 == __last2)
      { // if second sequence is empty
          return false;
      }
      else if (__first1 == __last1)
      { // if first sequence is empty
          return true;
      }
      else
      {
          typedef typename ::std::iterator_traits<_ForwardIterator1>::reference ref_type1;
          typedef typename ::std::iterator_traits<_ForwardIterator2>::reference ref_type2;
          --__last1;
          --__last2;
          auto __n = ::std::min(__last1 - __first1, __last2 - __first2);
          ::std::pair<_ForwardIterator1, _ForwardIterator2> __result = __unseq_backend::__simd_first(
              __first1, __n, __first2, [__comp](const ref_type1 __x, const ref_type2 __y) mutable {
                  return __comp(__x, __y) || __comp(__y, __x);
              });
  
          if (__result.first == __last1 && __result.second != __last2)
          { // if first sequence shorter than second
              return !__comp(*__result.second, *__result.first);
          }
          else
          { // if second sequence shorter than first or both have the same number of elements
              return __comp(*__result.first, *__result.second);
          }
      }
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _Compare, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, bool>
  __pattern_lexicographical_compare(_ExecutionPolicy&&, _ForwardIterator1 __first1, _ForwardIterator1 __last1,
                                    _ForwardIterator2 __first2, _ForwardIterator2 __last2, _Compare __comp,
                                    _IsVector __is_vector, /* is_parallel = */ ::std::false_type) noexcept
  {
      return __internal::__brick_lexicographical_compare(__first1, __last1, __first2, __last2, __comp, __is_vector);
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _Compare, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, bool>
  __pattern_lexicographical_compare(_ExecutionPolicy&& __exec, _ForwardIterator1 __first1, _ForwardIterator1 __last1,
                                    _ForwardIterator2 __first2, _ForwardIterator2 __last2, _Compare __comp,
                                    _IsVector __is_vector, /* is_parallel = */ ::std::true_type)
  {
      if (__first2 == __last2)
      { // if second sequence is empty
          return false;
      }
      else if (__first1 == __last1)
      { // if first sequence is empty
          return true;
      }
      else
      {
          typedef typename ::std::iterator_traits<_ForwardIterator1>::reference _RefType1;
          typedef typename ::std::iterator_traits<_ForwardIterator2>::reference _RefType2;
          --__last1;
          --__last2;
          auto __n = ::std::min(__last1 - __first1, __last2 - __first2);
          auto __result = __internal::__parallel_find(
              ::std::forward<_ExecutionPolicy>(__exec), __first1, __first1 + __n,
              [__first1, __first2, &__comp, __is_vector](_ForwardIterator1 __i, _ForwardIterator1 __j) {
                  return __brick_mismatch(__i, __j, __first2 + (__i - __first1), __first2 + (__j - __first1),
                                          [&__comp](const _RefType1 __x, const _RefType2 __y) {
                                              return !__comp(__x, __y) && !__comp(__y, __x);
                                          },
                                          __is_vector)
                      .first;
              },
              ::std::true_type{});
  
          if (__result == __last1 && __first2 + (__result - __first1) != __last2)
          { // if first sequence shorter than second
              return !__comp(*(__first2 + (__result - __first1)), *__result);
          }
          else
          { // if second sequence shorter than first or both have the same number of elements
              return __comp(*__result, *(__first2 + (__result - __first1)));
          }
      }
  }
  
  //------------------------------------------------------------------------
  // swap
  //------------------------------------------------------------------------
  
  template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _Function, class _IsVector,
            class _IsParallel>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _ForwardIterator2>
  __pattern_swap(_ExecutionPolicy&& __exec, _ForwardIterator1 __first1, _ForwardIterator1 __last1,
                 _ForwardIterator2 __first2, _Function __f, _IsVector __is_vector, _IsParallel __is_parallel)
  {
      return __pattern_walk2(::std::forward<_ExecutionPolicy>(__exec), __first1, __last1, __first2, __f, __is_vector,
                             __is_parallel);
  }
  
  //------------------------------------------------------------------------
  // shift_left
  //------------------------------------------------------------------------
  
  template <class _ForwardIterator>
  _ForwardIterator
  __brick_shift_left(_ForwardIterator __first, _ForwardIterator __last,
                     typename ::std::iterator_traits<_ForwardIterator>::difference_type __n,
                     /*is_vector=*/::std::false_type) noexcept
  {
  #if _ONEDPL_CPP20_SHIFT_LEFT_RIGHT_PRESENT
      return ::std::shift_left(__first, __last, __n);
  #else
      //If (n > 0 && n < m), returns first + (m - n). Otherwise, if n  > 0, returns first. Otherwise, returns last.
      if (__n <= 0)
          return __last;
  
      //seek for (first + n)
      auto __it = oneapi::dpl::__internal::__next_to_last()(__first, __last, __n);
      if (__it == __last) // n >= last - first;
          return __first;
  
      //Moving the rest elements from a position number n to the begin of the sequence.
      for (; __it != __last; ++__it, ++__first)
          *__first = ::std::move(*__it);
  
      return __first;
  #endif
  }
  
  template <class _ForwardIterator>
  _ForwardIterator
  __brick_shift_left(_ForwardIterator __first, _ForwardIterator __last,
                     typename ::std::iterator_traits<_ForwardIterator>::difference_type __n,
                     /*is_vector=*/::std::true_type) noexcept
  {
      //If (n > 0 && n < m), returns first + (m - n). Otherwise, if n  > 0, returns first. Otherwise, returns last.
      if (__n <= 0)
          return __last;
      auto __size = __last - __first;
      if (__n >= __size)
          return __first;
  
      using _DiffType = typename ::std::iterator_traits<_ForwardIterator>::difference_type;
      using _ReferenceType = typename ::std::iterator_traits<_ForwardIterator>::reference;
  
      _DiffType __mid = __size / 2 + __size % 2;
      _DiffType __size_res = __size - __n;
  
      //1. n >= size/2; there is enough memory to 'total' parallel (SIMD) copying
      if (__n >= __mid)
      {
          __unseq_backend::__simd_walk_2(__first + __n, __size_res, __first,
                                         [](_ReferenceType __x, _ReferenceType __y) { __y = ::std::move(__x); });
      }
      else //2. n < size/2; there is not enough memory to parallel (SIMD) copying; doing SIMD copying by n elements
      {
          for (auto __k = __n; __k < __size; __k += __n)
          {
              auto __end = ::std::min(__k + __n, __size);
              __unseq_backend::__simd_walk_2(__first + __k, __end - __k, __first + __k - __n,
                                             [](_ReferenceType __x, _ReferenceType __y) { __y = ::std::move(__x); });
          }
      }
  
      return __first + __size_res;
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _ForwardIterator>
  __pattern_shift_left(_ExecutionPolicy&&, _ForwardIterator __first, _ForwardIterator __last,
                       typename ::std::iterator_traits<_ForwardIterator>::difference_type __n, _IsVector __is_vector,
                       /*is_parallel=*/::std::false_type) noexcept
  {
      return __brick_shift_left(__first, __last, __n, __is_vector);
  }
  
  template <class _ExecutionPolicy, class _ForwardIterator, class _IsVector>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _ForwardIterator>
  __pattern_shift_left(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last,
                       typename ::std::iterator_traits<_ForwardIterator>::difference_type __n, _IsVector __is_vector,
                       /*is_parallel=*/::std::true_type)
  {
      //If (n > 0 && n < m), returns first + (m - n). Otherwise, if n  > 0, returns first. Otherwise, returns last.
      if (__n <= 0)
          return __last;
      auto __size = __last - __first;
      if (__n >= __size)
          return __first;
  
      using _DiffType = typename ::std::iterator_traits<_ForwardIterator>::difference_type;
  
      _DiffType __mid = __size / 2 + __size % 2;
      _DiffType __size_res = __size - __n;
  
      //1. n >= size/2; there is enough memory to 'total' parallel copying
      if (__n >= __mid)
      {
          __par_backend::__parallel_for(::std::forward<_ExecutionPolicy>(__exec), __n, __size,
                                        [__first, __n, __is_vector](_DiffType __i, _DiffType __j) {
                                            __brick_move<_ExecutionPolicy>{}(__first + __i, __first + __j,
                                                                             __first + __i - __n, __is_vector);
                                        });
      }
      else //2. n < size/2; there is not enough memory to parallel copying; doing parallel copying by n elements
      {
          //TODO: to consider parallel processing by the 'internal' loop (but we may probably get cache locality issues)
          for (auto __k = __n; __k < __size; __k += __n)
          {
              auto __end = ::std::min(__k + __n, __size);
              __par_backend::__parallel_for(::std::forward<_ExecutionPolicy>(__exec), __k, __end,
                                            [__first, __k, __n, __is_vector](_DiffType __i, _DiffType __j) {
                                                __brick_move<_ExecutionPolicy>{}(__first + __i, __first + __j,
                                                                                 __first + __i - __n, __is_vector);
                                            });
          }
      }
  
      return __first + __size_res;
  }
  
  template <class _ExecutionPolicy, class _BidirectionalIterator, class _IsVector, class _IsParallel>
  oneapi::dpl::__internal::__enable_if_host_execution_policy<_ExecutionPolicy, _BidirectionalIterator>
  __pattern_shift_right(_ExecutionPolicy&& __exec, _BidirectionalIterator __first, _BidirectionalIterator __last,
                        typename ::std::iterator_traits<_BidirectionalIterator>::difference_type __n,
                        _IsVector __is_vector, _IsParallel is_parallel)
  {
      using _ReverseIterator = typename ::std::reverse_iterator<_BidirectionalIterator>;
      auto __res = oneapi::dpl::__internal::__pattern_shift_left(::std::forward<_ExecutionPolicy>(__exec),
                                                                 _ReverseIterator(__last), _ReverseIterator(__first), __n,
                                                                 __is_vector, is_parallel);
  
      return __res.base();
  }
  
  } // namespace __internal
  } // namespace dpl
  } // namespace oneapi
  
  #endif /* _ONEDPL_ALGORITHM_IMPL_H */
  