text: /*
   *  Copyright 2008-2013 NVIDIA Corporation
   *
   *  Licensed under the Apache License, Version 2.0 (the "License");
   *  you may not use this file except in compliance with the License.
   *  You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   *  Unless required by applicable law or agreed to in writing, software
   *  distributed under the License is distributed on an "AS IS" BASIS,
   *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   *  See the License for the specific language governing permissions and
   *  limitations under the License.
   */
  
  
  /*! \file thrust/transform.h
   *  \brief Transforms input ranges using a function object
   */
  
  #pragma once
  
  #include <thrust/detail/config.h>
  #include <thrust/detail/execution_policy.h>
  
  namespace thrust
  {
  
  
  /*! \addtogroup algorithms
   */
  
  /*! \addtogroup transformations
   *  \ingroup algorithms
   *  \{
   */
  
  
  /*! This version of \p transform applies a unary function to each element
   *  of an input sequence and stores the result in the corresponding 
   *  position in an output sequence.  Specifically, for each iterator 
   *  <tt>i</tt> in the range [\p first, \p last) the operation 
   *  <tt>op(*i)</tt> is performed and the result is assigned to <tt>*o</tt>,
   *  where <tt>o</tt> is the corresponding output iterator in the range
   *  [\p result, \p result + (\p last - \p first) ).  The input and
   *  output sequences may coincide, resulting in an in-place transformation.
   *
   *  The algorithm's execution is parallelized as determined by \p exec.
   *    
   *  \param exec The execution policy to use for parallelization.
   *  \param first The beginning of the input sequence.
   *  \param last The end of the input sequence.
   *  \param result The beginning of the output sequence.
   *  \param op The transformation operation.
   *  \return The end of the output sequence.
   *
   *  \tparam DerivedPolicy The name of the derived execution policy.
   *  \tparam InputIterator is a model of <a href="https://en.cppreference.com/w/cpp/iterator/input_iterator">Input Iterator</a>
   *                        and \c InputIterator's \c value_type is convertible to \c UnaryFunction's \c argument_type.
   *  \tparam OutputIterator is a model of <a href="https://en.cppreference.com/w/cpp/iterator/output_iterator">Output Iterator</a>.
   *  \tparam UnaryFunction is a model of <a href="https://en.cppreference.com/w/cpp/utility/functional/unary_function">Unary Function</a>
   *                              and \c UnaryFunction's \c result_type is convertible to \c OutputIterator's \c value_type.
   *
   *  \pre \p first may equal \p result, but the range <tt>[first, last)</tt> shall not overlap the range <tt>[result, result + (last - first))</tt> otherwise.
   *
   *  The following code snippet demonstrates how to use \p transform to negate a range in-place
   *  using the \p thrust::host execution policy for parallelization:
   *
   *  \code
   *  #include <thrust/transform.h>
   *  #include <thrust/functional.h>
   *  #include <thrust/execution_policy.h>
   *  ...
   *  
   *  int data[10] = {-5, 0, 2, -3, 2, 4, 0, -1, 2, 8};
   * 
   *  thrust::negate<int> op;
   *
   *  thrust::transform(thrust::host, data, data + 10, data, op); // in-place transformation
   *
   *  // data is now {5, 0, -2, 3, -2, -4, 0, 1, -2, -8};
   *  \endcode
   *
   *  \see https://en.cppreference.com/w/cpp/algorithm/transform
   */
  template<typename DerivedPolicy,
           typename InputIterator,
           typename OutputIterator,
           typename UnaryFunction>
  __host__ __device__
    OutputIterator transform(const thrust::detail::execution_policy_base<DerivedPolicy> &exec,
                             InputIterator first, InputIterator last,
                             OutputIterator result,
                             UnaryFunction op);
  
  	
  /*! This version of \p transform applies a unary function to each element
   *  of an input sequence and stores the result in the corresponding 
   *  position in an output sequence.  Specifically, for each iterator 
   *  <tt>i</tt> in the range [\p first, \p last) the operation 
   *  <tt>op(*i)</tt> is performed and the result is assigned to <tt>*o</tt>,
   *  where <tt>o</tt> is the corresponding output iterator in the range
   *  [\p result, \p result + (\p last - \p first) ).  The input and
   *  output sequences may coincide, resulting in an in-place transformation.
   *    
   *  \param first The beginning of the input sequence.
   *  \param last The end of the input sequence.
   *  \param result The beginning of the output sequence.
   *  \param op The tranformation operation.
   *  \return The end of the output sequence.
   *
   *  \tparam InputIterator is a model of <a href="https://en.cppreference.com/w/cpp/iterator/input_iterator">Input Iterator</a>
   *                        and \c InputIterator's \c value_type is convertible to \c UnaryFunction's \c argument_type.
   *  \tparam OutputIterator is a model of <a href="https://en.cppreference.com/w/cpp/iterator/output_iterator">Output Iterator</a>.
   *  \tparam UnaryFunction is a model of <a href="https://en.cppreference.com/w/cpp/utility/functional/unary_function">Unary Function</a>
   *                              and \c UnaryFunction's \c result_type is convertible to \c OutputIterator's \c value_type.
   *
   *  \pre \p first may equal \p result, but the range <tt>[first, last)</tt> shall not overlap the range <tt>[result, result + (last - first))</tt> otherwise.
   *
   *  The following code snippet demonstrates how to use \p transform
   *
   *  \code
   *  #include <thrust/transform.h>
   *  #include <thrust/functional.h>
   *  
   *  int data[10] = {-5, 0, 2, -3, 2, 4, 0, -1, 2, 8};
   * 
   *  thrust::negate<int> op;
   *
   *  thrust::transform(data, data + 10, data, op); // in-place transformation
   *
   *  // data is now {5, 0, -2, 3, -2, -4, 0, 1, -2, -8};
   *  \endcode
   *
   *  \see https://en.cppreference.com/w/cpp/algorithm/transform
   */
  template<typename InputIterator,
           typename OutputIterator,
           typename UnaryFunction>
    OutputIterator transform(InputIterator first, InputIterator last,
                             OutputIterator result,
                             UnaryFunction op);
  
  
  /*! This version of \p transform applies a binary function to each pair
   *  of elements from two input sequences and stores the result in the
   *  corresponding position in an output sequence.  Specifically, for
   *  each iterator <tt>i</tt> in the range [\p first1, \p last1) and 
   *  <tt>j = first + (i - first1)</tt> in the range [\p first2, \p last2)
   *  the operation <tt>op(*i,*j)</tt> is performed and the result is 
   *  assigned to <tt>*o</tt>,  where <tt>o</tt> is the corresponding
   *  output iterator in the range [\p result, \p result + (\p last - \p first) ).
   *  The input and output sequences may coincide, resulting in an 
   *  in-place transformation.
   *
   *  The algorithm's execution is parallelized as determined by \p exec.
   *    
   *  \param exec The execution policy to use for parallelization.
   *  \param first1 The beginning of the first input sequence.
   *  \param last1 The end of the first input sequence.
   *  \param first2 The beginning of the second input sequence.
   *  \param result The beginning of the output sequence.
   *  \param op The tranformation operation.
   *  \return The end of the output sequence.
   *
   *  \tparam DerivedPolicy The name of the derived execution policy.
   *  \tparam InputIterator1 is a model of <a href="https://en.cppreference.com/w/cpp/iterator/input_iterator">Input Iterator</a>
   *                        and \c InputIterator1's \c value_type is convertible to \c BinaryFunction's \c first_argument_type.
   *  \tparam InputIterator2 is a model of <a href="https://en.cppreference.com/w/cpp/iterator/input_iterator">Input Iterator</a>
   *                        and \c InputIterator2's \c value_type is convertible to \c BinaryFunction's \c second_argument_type.
   *  \tparam OutputIterator is a model of <a href="https://en.cppreference.com/w/cpp/iterator/output_iterator">Output Iterator</a>.
   *  \tparam BinaryFunction is a model of <a href="https://en.cppreference.com/w/cpp/utility/functional/binary_function">Binary Function</a>
   *                              and \c BinaryFunction's \c result_type is convertible to \c OutputIterator's \c value_type.
   *
   *  \pre \p first1 may equal \p result, but the range <tt>[first1, last1)</tt> shall not overlap the range <tt>[result, result + (last1 - first1))</tt> otherwise.
   *  \pre \p first2 may equal \p result, but the range <tt>[first2, first2 + (last1 - first1))</tt> shall not overlap the range <tt>[result, result + (last1 - first1))</tt> otherwise.
   *
   *  The following code snippet demonstrates how to use \p transform to compute the sum of two
   *  ranges using the \p thrust::host execution policy for parallelization:
   *
   *  \code
   *  #include <thrust/transform.h>
   *  #include <thrust/functional.h>
   *  #include <thrust/execution_policy.h>
   *  ...
   *  
   *  int input1[6] = {-5,  0,  2,  3,  2,  4};
   *  int input2[6] = { 3,  6, -2,  1,  2,  3};
   *  int output[6];
   * 
   *  thrust::plus<int> op;
   *
   *  thrust::transform(thrust::host, input1, input1 + 6, input2, output, op);
   *
   *  // output is now {-2,  6,  0,  4,  4,  7};
   *  \endcode
   *
   *  \see https://en.cppreference.com/w/cpp/algorithm/transform
   */
  template<typename DerivedPolicy,
           typename InputIterator1,
           typename InputIterator2,
           typename OutputIterator,
           typename BinaryFunction>
  __host__ __device__
    OutputIterator transform(const thrust::detail::execution_policy_base<DerivedPolicy> &exec,
                             InputIterator1 first1, InputIterator1 last1,
                             InputIterator2 first2,
                             OutputIterator result,
                             BinaryFunction op);
  
  
  /*! This version of \p transform applies a binary function to each pair
   *  of elements from two input sequences and stores the result in the
   *  corresponding position in an output sequence.  Specifically, for
   *  each iterator <tt>i</tt> in the range [\p first1, \p last1) and 
   *  <tt>j = first + (i - first1)</tt> in the range [\p first2, \p last2)
   *  the operation <tt>op(*i,*j)</tt> is performed and the result is 
   *  assigned to <tt>*o</tt>,  where <tt>o</tt> is the corresponding
   *  output iterator in the range [\p result, \p result + (\p last - \p first) ).
   *  The input and output sequences may coincide, resulting in an 
   *  in-place transformation.
   *    
   *  \param first1 The beginning of the first input sequence.
   *  \param last1 The end of the first input sequence.
   *  \param first2 The beginning of the second input sequence.
   *  \param result The beginning of the output sequence.
   *  \param op The tranformation operation.
   *  \return The end of the output sequence.
   *
   *  \tparam InputIterator1 is a model of <a href="https://en.cppreference.com/w/cpp/iterator/input_iterator">Input Iterator</a>
   *                        and \c InputIterator1's \c value_type is convertible to \c BinaryFunction's \c first_argument_type.
   *  \tparam InputIterator2 is a model of <a href="https://en.cppreference.com/w/cpp/iterator/input_iterator">Input Iterator</a>
   *                        and \c InputIterator2's \c value_type is convertible to \c BinaryFunction's \c second_argument_type.
   *  \tparam OutputIterator is a model of <a href="https://en.cppreference.com/w/cpp/iterator/output_iterator">Output Iterator</a>.
   *  \tparam BinaryFunction is a model of <a href="https://en.cppreference.com/w/cpp/utility/functional/binary_function">Binary Function</a>
   *                              and \c BinaryFunction's \c result_type is convertible to \c OutputIterator's \c value_type.
   *
   *  \pre \p first1 may equal \p result, but the range <tt>[first1, last1)</tt> shall not overlap the range <tt>[result, result + (last1 - first1))</tt> otherwise.
   *  \pre \p first2 may equal \p result, but the range <tt>[first2, first2 + (last1 - first1))</tt> shall not overlap the range <tt>[result, result + (last1 - first1))</tt> otherwise.
   *
   *  The following code snippet demonstrates how to use \p transform
   *
   *  \code
   *  #include <thrust/transform.h>
   *  #include <thrust/functional.h>
   *  
   *  int input1[6] = {-5,  0,  2,  3,  2,  4};
   *  int input2[6] = { 3,  6, -2,  1,  2,  3};
   *  int output[6];
   * 
   *  thrust::plus<int> op;
   *
   *  thrust::transform(input1, input1 + 6, input2, output, op);
   *
   *  // output is now {-2,  6,  0,  4,  4,  7};
   *  \endcode
   *
   *  \see https://en.cppreference.com/w/cpp/algorithm/transform
   */
  template<typename InputIterator1,
           typename InputIterator2,
           typename OutputIterator,
           typename BinaryFunction>
    OutputIterator transform(InputIterator1 first1, InputIterator1 last1,
                             InputIterator2 first2,
                             OutputIterator result,
                             BinaryFunction op);
  
  
  /*! This version of \p transform_if conditionally applies a unary function
   *  to each element of an input sequence and stores the result in the corresponding 
   *  position in an output sequence if the corresponding position in the input sequence
   *  satifies a predicate. Otherwise, the corresponding position in the
   *  output sequence is not modified.
   *
   *  Specifically, for each iterator <tt>i</tt> in the range <tt>[first, last)</tt> the
   *  predicate <tt>pred(*i)</tt> is evaluated. If this predicate
   *  evaluates to \c true, the result of <tt>op(*i)</tt> is assigned to <tt>*o</tt>,
   *  where <tt>o</tt> is the corresponding output iterator in the range
   *  <tt>[result, result + (last - first) )</tt>. Otherwise, <tt>op(*i)</tt> is
   *  not evaluated and no assignment occurs. The input and output sequences may coincide,
   *  resulting in an in-place transformation.
   *
   *  The algorithm's execution is parallelized as determined by \p exec.
   *    
   *  \param exec The execution policy to use for parallelization.
   *  \param first The beginning of the input sequence.
   *  \param last The end of the input sequence.
   *  \param result The beginning of the output sequence.
   *  \param op The tranformation operation.
   *  \param pred The predicate operation.
   *  \return The end of the output sequence.
   *
   *  \tparam DerivedPolicy The name of the derived execution policy.
   *  \tparam InputIterator is a model of <a href="https://en.cppreference.com/w/cpp/iterator/input_iterator">Input Iterator</a>,
   *                        and \c InputIterator's \c value_type is convertible to \c Predicate's \c argument_type,
   *                        and \c InputIterator's \c value_type is convertible to \c UnaryFunction's \c argument_type.
   *  \tparam ForwardIterator is a model of <a href="https://en.cppreference.com/w/cpp/iterator/forward_iterator">Forward Iterator</a>.
   *  \tparam UnaryFunction is a model of <a href="https://en.cppreference.com/w/cpp/utility/functional/unary_function">Unary Function</a>
   *                        and \c UnaryFunction's \c result_type is convertible to \c OutputIterator's \c value_type.
   *  \tparam Predicate is a model of <a href="https://en.cppreference.com/w/cpp/concepts/predicate">Predicate</a>.
   *
   *  \pre \p first may equal \p result, but the range <tt>[first, last)</tt> shall not overlap the range <tt>[result, result + (last - first))</tt> otherwise.
   *
   *  The following code snippet demonstrates how to use \p transform_if to negate the odd-valued
   *  elements of a range using the \p thrust::host execution policy for parallelization:
   *
   *  \code
   *  #include <thrust/transform.h>
   *  #include <thrust/functional.h>
   *  #include <thrust/execution_policy.h>
   *  ...
   *  
   *  int data[10]    = {-5, 0, 2, -3, 2, 4, 0, -1, 2, 8};
   *
   *  struct is_odd
   *  {
   *    __host__ __device__
   *    bool operator()(int x)
   *    {
   *      return x % 2;
   *    }
   *  };
   * 
   *  thrust::negate<int> op;
   *  thrust::identity<int> identity;
   *
   *  // negate odd elements
   *  thrust::transform_if(thrust::host, data, data + 10, data, op, is_odd()); // in-place transformation
   *
   *  // data is now {5, 0, 2, 3, 2, 4, 0, 1, 2, 8};
   *  \endcode
   *
   *  \see thrust::transform
   */
  template<typename DerivedPolicy,
           typename InputIterator,
           typename ForwardIterator,
           typename UnaryFunction,
           typename Predicate>
  __host__ __device__
    ForwardIterator transform_if(const thrust::detail::execution_policy_base<DerivedPolicy> &exec,
                                 InputIterator first, InputIterator last,
                                 ForwardIterator result,
                                 UnaryFunction op,
                                 Predicate pred);
  
  
  /*! This version of \p transform_if conditionally applies a unary function
   *  to each element of an input sequence and stores the result in the corresponding 
   *  position in an output sequence if the corresponding position in the input sequence
   *  satifies a predicate. Otherwise, the corresponding position in the
   *  output sequence is not modified.
   *
   *  Specifically, for each iterator <tt>i</tt> in the range <tt>[first, last)</tt> the
   *  predicate <tt>pred(*i)</tt> is evaluated. If this predicate
   *  evaluates to \c true, the result of <tt>op(*i)</tt> is assigned to <tt>*o</tt>,
   *  where <tt>o</tt> is the corresponding output iterator in the range
   *  <tt>[result, result + (last - first) )</tt>. Otherwise, <tt>op(*i)</tt> is
   *  not evaluated and no assignment occurs. The input and output sequences may coincide,
   *  resulting in an in-place transformation.
   *    
   *  \param first The beginning of the input sequence.
   *  \param last The end of the input sequence.
   *  \param result The beginning of the output sequence.
   *  \param op The tranformation operation.
   *  \param pred The predicate operation.
   *  \return The end of the output sequence.
   *
   *  \tparam InputIterator is a model of <a href="https://en.cppreference.com/w/cpp/iterator/input_iterator">Input Iterator</a>,
   *                        and \c InputIterator's \c value_type is convertible to \c Predicate's \c argument_type,
   *                        and \c InputIterator's \c value_type is convertible to \c UnaryFunction's \c argument_type.
   *  \tparam ForwardIterator is a model of <a href="https://en.cppreference.com/w/cpp/iterator/forward_iterator">Forward Iterator</a>.
   *  \tparam UnaryFunction is a model of <a href="https://en.cppreference.com/w/cpp/utility/functional/unary_function">Unary Function</a>
   *                        and \c UnaryFunction's \c result_type is convertible to \c OutputIterator's \c value_type.
   *  \tparam Predicate is a model of <a href="https://en.cppreference.com/w/cpp/concepts/predicate">Predicate</a>.
   *
   *  \pre \p first may equal \p result, but the range <tt>[first, last)</tt> shall not overlap the range <tt>[result, result + (last - first))</tt> otherwise.
   *
   *  The following code snippet demonstrates how to use \p transform_if:
   *
   *  \code
   *  #include <thrust/transform.h>
   *  #include <thrust/functional.h>
   *  
   *  int data[10]    = {-5, 0, 2, -3, 2, 4, 0, -1, 2, 8};
   *
   *  struct is_odd
   *  {
   *    __host__ __device__
   *    bool operator()(int x)
   *    {
   *      return x % 2;
   *    }
   *  };
   * 
   *  thrust::negate<int> op;
   *  thrust::identity<int> identity;
   *
   *  // negate odd elements
   *  thrust::transform_if(data, data + 10, data, op, is_odd()); // in-place transformation
   *
   *  // data is now {5, 0, 2, 3, 2, 4, 0, 1, 2, 8};
   *  \endcode
   *
   *  \see thrust::transform
   */
  template<typename InputIterator,
           typename ForwardIterator,
           typename UnaryFunction,
           typename Predicate>
    ForwardIterator transform_if(InputIterator first, InputIterator last,
                                 ForwardIterator result,
                                 UnaryFunction op,
                                 Predicate pred);
  
  
  /*! This version of \p transform_if conditionally applies a unary function
   *  to each element of an input sequence and stores the result in the corresponding 
   *  position in an output sequence if the corresponding position in a stencil sequence
   *  satisfies a predicate. Otherwise, the corresponding position in the
   *  output sequence is not modified.
   *
   *  Specifically, for each iterator <tt>i</tt> in the range <tt>[first, last)</tt> the
   *  predicate <tt>pred(*s)</tt> is evaluated, where <tt>s</tt> is the corresponding input
   *  iterator in the range <tt>[stencil, stencil + (last - first) )</tt>. If this predicate
   *  evaluates to \c true, the result of <tt>op(*i)</tt> is assigned to <tt>*o</tt>,
   *  where <tt>o</tt> is the corresponding output iterator in the range
   *  <tt>[result, result + (last - first) )</tt>. Otherwise, <tt>op(*i)</tt> is
   *  not evaluated and no assignment occurs. The input and output sequences may coincide,
   *  resulting in an in-place transformation.
   *
   *  The algorithm's execution is parallelized as determined by \p exec.
   *    
   *  \param exec The execution policy to use for parallelization.
   *  \param first The beginning of the input sequence.
   *  \param last The end of the input sequence.
   *  \param stencil The beginning of the stencil sequence.
   *  \param result The beginning of the output sequence.
   *  \param op The tranformation operation.
   *  \param pred The predicate operation.
   *  \return The end of the output sequence.
   *
   *  \tparam DerivedPolicy The name of the derived execution policy.
   *  \tparam InputIterator1 is a model of <a href="https://en.cppreference.com/w/cpp/iterator/input_iterator">Input Iterator</a>
   *                         and \c InputIterator1's \c value_type is convertible to \c UnaryFunction's \c argument_type.
   *  \tparam InputIterator2 is a model of <a href="https://en.cppreference.com/w/cpp/iterator/input_iterator">Input Iterator</a>
   *                         and \c InputIterator2's \c value_type is convertible to \c Predicate's \c argument_type.
   *  \tparam ForwardIterator is a model of <a href="https://en.cppreference.com/w/cpp/iterator/forward_iterator">Forward Iterator</a>.
   *  \tparam UnaryFunction is a model of <a href="https://en.cppreference.com/w/cpp/utility/functional/unary_function">Unary Function</a>
   *                        and \c UnaryFunction's \c result_type is convertible to \c OutputIterator's \c value_type.
   *  \tparam Predicate is a model of <a href="https://en.cppreference.com/w/cpp/concepts/predicate">Predicate</a>.
   *
   *  \pre \p first may equal \p result, but the range <tt>[first, last)</tt> shall not overlap the range <tt>[result, result + (last - first))</tt> otherwise.
   *  \pre \p stencil may equal \p result, but the range <tt>[stencil, stencil + (last - first))</tt> shall not overlap the range <tt>[result, result + (last - first))</tt> otherwise.
   *
   *  The following code snippet demonstrates how to use \p transform_if using the \p thrust::host
   *  execution policy for parallelization:
   *
   *  \code
   *  #include <thrust/transform.h>
   *  #include <thrust/functional.h>
   *  #include <thrust/execution_policy.h>
   *  ...
   *  
   *  int data[10]    = {-5, 0, 2, -3, 2, 4, 0, -1, 2, 8};
   *  int stencil[10] = { 1, 0, 1,  0, 1, 0, 1,  0, 1, 0};
   * 
   *  thrust::negate<int> op;
   *  thrust::identity<int> identity;
   *
   *  thrust::transform_if(thrust::host, data, data + 10, stencil, data, op, identity); // in-place transformation
   *
   *  // data is now {5, 0, -2, -3, -2,  4, 0, -1, -2,  8};
   *  \endcode
   *
   *  \see thrust::transform
   */
  template<typename DerivedPolicy,
           typename InputIterator1,
           typename InputIterator2,
           typename ForwardIterator,
           typename UnaryFunction,
           typename Predicate>
  __host__ __device__
    ForwardIterator transform_if(const thrust::detail::execution_policy_base<DerivedPolicy> &exec,
                                 InputIterator1 first, InputIterator1 last,
                                 InputIterator2 stencil,
                                 ForwardIterator result,
                                 UnaryFunction op,
                                 Predicate pred);
  
  
  /*! This version of \p transform_if conditionally applies a unary function
   *  to each element of an input sequence and stores the result in the corresponding 
   *  position in an output sequence if the corresponding position in a stencil sequence
   *  satisfies a predicate. Otherwise, the corresponding position in the
   *  output sequence is not modified.
   *
   *  Specifically, for each iterator <tt>i</tt> in the range <tt>[first, last)</tt> the
   *  predicate <tt>pred(*s)</tt> is evaluated, where <tt>s</tt> is the corresponding input
   *  iterator in the range <tt>[stencil, stencil + (last - first) )</tt>. If this predicate
   *  evaluates to \c true, the result of <tt>op(*i)</tt> is assigned to <tt>*o</tt>,
   *  where <tt>o</tt> is the corresponding output iterator in the range
   *  <tt>[result, result + (last - first) )</tt>. Otherwise, <tt>op(*i)</tt> is
   *  not evaluated and no assignment occurs. The input and output sequences may coincide,
   *  resulting in an in-place transformation.
   *    
   *  \param first The beginning of the input sequence.
   *  \param last The end of the input sequence.
   *  \param stencil The beginning of the stencil sequence.
   *  \param result The beginning of the output sequence.
   *  \param op The tranformation operation.
   *  \param pred The predicate operation.
   *  \return The end of the output sequence.
   *
   *  \tparam InputIterator1 is a model of <a href="https://en.cppreference.com/w/cpp/iterator/input_iterator">Input Iterator</a>
   *                         and \c InputIterator1's \c value_type is convertible to \c UnaryFunction's \c argument_type.
   *  \tparam InputIterator2 is a model of <a href="https://en.cppreference.com/w/cpp/iterator/input_iterator">Input Iterator</a>
   *                         and \c InputIterator2's \c value_type is convertible to \c Predicate's \c argument_type.
   *  \tparam ForwardIterator is a model of <a href="https://en.cppreference.com/w/cpp/iterator/forward_iterator">Forward Iterator</a>.
   *  \tparam UnaryFunction is a model of <a href="https://en.cppreference.com/w/cpp/utility/functional/unary_function">Unary Function</a>
   *                        and \c UnaryFunction's \c result_type is convertible to \c OutputIterator's \c value_type.
   *  \tparam Predicate is a model of <a href="https://en.cppreference.com/w/cpp/concepts/predicate">Predicate</a>.
   *
   *  \pre \p first may equal \p result, but the range <tt>[first, last)</tt> shall not overlap the range <tt>[result, result + (last - first))</tt> otherwise.
   *  \pre \p stencil may equal \p result, but the range <tt>[stencil, stencil + (last - first))</tt> shall not overlap the range <tt>[result, result + (last - first))</tt> otherwise.
   *
   *  The following code snippet demonstrates how to use \p transform_if:
   *
   *  \code
   *  #include <thrust/transform.h>
   *  #include <thrust/functional.h>
   *  
   *  int data[10]    = {-5, 0, 2, -3, 2, 4, 0, -1, 2, 8};
   *  int stencil[10] = { 1, 0, 1,  0, 1, 0, 1,  0, 1, 0};
   * 
   *  thrust::negate<int> op;
   *  thrust::identity<int> identity;
   *
   *  thrust::transform_if(data, data + 10, stencil, data, op, identity); // in-place transformation
   *
   *  // data is now {5, 0, -2, -3, -2,  4, 0, -1, -2,  8};
   *  \endcode
   *
   *  \see thrust::transform
   */
  template<typename InputIterator1,
           typename InputIterator2,
           typename ForwardIterator,
           typename UnaryFunction,
           typename Predicate>
    ForwardIterator transform_if(InputIterator1 first, InputIterator1 last,
                                 InputIterator2 stencil,
                                 ForwardIterator result,
                                 UnaryFunction op,
                                 Predicate pred);
  
  
  /*! This version of \p transform_if conditionally applies a binary function
   *  to each pair of elements from two input sequences and stores the result in the corresponding 
   *  position in an output sequence if the corresponding position in a stencil sequence
   *  satifies a predicate. Otherwise, the corresponding position in the
   *  output sequence is not modified.
   *
   *  Specifically, for each iterator <tt>i</tt> in the range <tt>[first1, last1)</tt> and 
   *  <tt>j = first2 + (i - first1)</tt> in the range <tt>[first2, first2 + (last1 - first1) )</tt>,
   *  the predicate <tt>pred(*s)</tt> is evaluated, where <tt>s</tt> is the corresponding input
   *  iterator in the range <tt>[stencil, stencil + (last1 - first1) )</tt>. If this predicate
   *  evaluates to \c true, the result of <tt>binary_op(*i,*j)</tt> is assigned to <tt>*o</tt>,
   *  where <tt>o</tt> is the corresponding output iterator in the range
   *  <tt>[result, result + (last1 - first1) )</tt>. Otherwise, <tt>binary_op(*i,*j)</tt> is
   *  not evaluated and no assignment occurs. The input and output sequences may coincide,
   *  resulting in an in-place transformation.
   *
   *  The algorithm's execution is parallelized as determined by \p exec.
   *    
   *  \param exec The execution policy to use for parallelization.
   *  \param first1 The beginning of the first input sequence.
   *  \param last1 The end of the first input sequence.
   *  \param first2 The beginning of the second input sequence.
   *  \param stencil The beginning of the stencil sequence.
   *  \param result The beginning of the output sequence.
   *  \param binary_op The transformation operation.
   *  \param pred The predicate operation.
   *  \return The end of the output sequence.
   *
   *  \tparam DerivedPolicy The name of the derived execution policy.
   *  \tparam InputIterator1 is a model of <a href="https://en.cppreference.com/w/cpp/iterator/input_iterator">Input Iterator</a>
   *                         and \c InputIterator1's \c value_type is convertible to \c BinaryFunction's \c first_argument_type.
   *  \tparam InputIterator2 is a model of <a href="https://en.cppreference.com/w/cpp/iterator/input_iterator">Input Iterator</a>
   *                         and \c InputIterator2's \c value_type is convertible to \c BinaryFunction's \c second_argument_type.
   *  \tparam ForwardIterator is a model of <a href="https://en.cppreference.com/w/cpp/iterator/forward_iterator">Forward Iterator</a>.
   *  \tparam BinaryFunction is a model of <a href="https://en.cppreference.com/w/cpp/utility/functional/binary_function">Binary Function</a>
   *                         and \c BinaryFunction's \c result_type is convertible to \c OutputIterator's \c value_type.
   *  \tparam Predicate is a model of <a href="https://en.cppreference.com/w/cpp/concepts/predicate">Predicate</a>.
   *
   *  \pre \p first1 may equal \p result, but the range <tt>[first1, last1)</tt> shall not overlap the range <tt>[result, result + (last1 - first1))</tt> otherwise.
   *  \pre \p first2 may equal \p result, but the range <tt>[first2, first2 + (last1 - first1))</tt> shall not overlap the range <tt>[result, result + (last1 - first1))</tt> otherwise.
   *  \pre \p stencil may equal \p result, but the range <tt>[stencil, stencil + (last1 - first1))</tt> shall not overlap the range <tt>[result, result + (last1 - first1))</tt> otherwise.
   *
   *  The following code snippet demonstrates how to use \p transform_if using the \p thrust::host
   *  execution policy for parallelization:
   *
   *  \code
   *  #include <thrust/transform.h>
   *  #include <thrust/functional.h>
   *  #include <thrust/execution_policy.h>
   *  ...
   *  
   *  int input1[6]  = {-5,  0,  2,  3,  2,  4};
   *  int input2[6]  = { 3,  6, -2,  1,  2,  3};
   *  int stencil[8] = { 1,  0,  1,  0,  1,  0};
   *  int output[6];
   * 
   *  thrust::plus<int> op;
   *  thrust::identity<int> identity;
   *
   *  thrust::transform_if(thrust::host, input1, input1 + 6, input2, stencil, output, op, identity);
   *
   *  // output is now {-2,  0,  0,  3,  4,  4};
   *  \endcode
   *
   *  \see thrust::transform
   */
  template<typename DerivedPolicy,
           typename InputIterator1,
           typename InputIterator2,
           typename InputIterator3,
           typename ForwardIterator,
           typename BinaryFunction,
           typename Predicate>
  __host__ __device__
    ForwardIterator transform_if(const thrust::detail::execution_policy_base<DerivedPolicy> &exec,
                                 InputIterator1 first1, InputIterator1 last1,
                                 InputIterator2 first2,
                                 InputIterator3 stencil,
                                 ForwardIterator result,
                                 BinaryFunction binary_op,
                                 Predicate pred);
  
  
  /*! This version of \p transform_if conditionally applies a binary function
   *  to each pair of elements from two input sequences and stores the result in the corresponding 
   *  position in an output sequence if the corresponding position in a stencil sequence
   *  satifies a predicate. Otherwise, the corresponding position in the
   *  output sequence is not modified.
   *
   *  Specifically, for each iterator <tt>i</tt> in the range <tt>[first1, last1)</tt> and 
   *  <tt>j = first2 + (i - first1)</tt> in the range <tt>[first2, first2 + (last1 - first1) )</tt>,
   *  the predicate <tt>pred(*s)</tt> is evaluated, where <tt>s</tt> is the corresponding input
   *  iterator in the range <tt>[stencil, stencil + (last1 - first1) )</tt>. If this predicate
   *  evaluates to \c true, the result of <tt>binary_op(*i,*j)</tt> is assigned to <tt>*o</tt>,
   *  where <tt>o</tt> is the corresponding output iterator in the range
   *  <tt>[result, result + (last1 - first1) )</tt>. Otherwise, <tt>binary_op(*i,*j)</tt> is
   *  not evaluated and no assignment occurs. The input and output sequences may coincide,
   *  resulting in an in-place transformation.
   *    
   *  \param first1 The beginning of the first input sequence.
   *  \param last1 The end of the first input sequence.
   *  \param first2 The beginning of the second input sequence.
   *  \param stencil The beginning of the stencil sequence.
   *  \param result The beginning of the output sequence.
   *  \param binary_op The transformation operation.
   *  \param pred The predicate operation.
   *  \return The end of the output sequence.
   *
   *  \tparam InputIterator1 is a model of <a href="https://en.cppreference.com/w/cpp/iterator/input_iterator">Input Iterator</a>
   *                         and \c InputIterator1's \c value_type is convertible to \c BinaryFunction's \c first_argument_type.
   *  \tparam InputIterator2 is a model of <a href="https://en.cppreference.com/w/cpp/iterator/input_iterator">Input Iterator</a>
   *                         and \c InputIterator2's \c value_type is convertible to \c BinaryFunction's \c second_argument_type.
   *  \tparam ForwardIterator is a model of <a href="https://en.cppreference.com/w/cpp/iterator/forward_iterator">Forward Iterator</a>.
   *  \tparam BinaryFunction is a model of <a href="https://en.cppreference.com/w/cpp/utility/functional/binary_function">Binary Function</a>
   *                         and \c BinaryFunction's \c result_type is convertible to \c OutputIterator's \c value_type.
   *  \tparam Predicate is a model of <a href="https://en.cppreference.com/w/cpp/concepts/predicate">Predicate</a>.
   *
   *  \pre \p first1 may equal \p result, but the range <tt>[first1, last1)</tt> shall not overlap the range <tt>[result, result + (last1 - first1))</tt> otherwise.
   *  \pre \p first2 may equal \p result, but the range <tt>[first2, first2 + (last1 - first1))</tt> shall not overlap the range <tt>[result, result + (last1 - first1))</tt> otherwise.
   *  \pre \p stencil may equal \p result, but the range <tt>[stencil, stencil + (last1 - first1))</tt> shall not overlap the range <tt>[result, result + (last1 - first1))</tt> otherwise.
   *
   *  The following code snippet demonstrates how to use \p transform_if:
   *
   *  \code
   *  #include <thrust/transform.h>
   *  #include <thrust/functional.h>
   *  
   *  int input1[6]  = {-5,  0,  2,  3,  2,  4};
   *  int input2[6]  = { 3,  6, -2,  1,  2,  3};
   *  int stencil[8] = { 1,  0,  1,  0,  1,  0};
   *  int output[6];
   * 
   *  thrust::plus<int> op;
   *  thrust::identity<int> identity;
   *
   *  thrust::transform_if(input1, input1 + 6, input2, stencil, output, op, identity);
   *
   *  // output is now {-2,  0,  0,  3,  4,  4};
   *  \endcode
   *
   *  \see thrust::transform
   */
  template<typename InputIterator1,
           typename InputIterator2,
           typename InputIterator3,
           typename ForwardIterator,
           typename BinaryFunction,
           typename Predicate>
    ForwardIterator transform_if(InputIterator1 first1, InputIterator1 last1,
                                 InputIterator2 first2,
                                 InputIterator3 stencil,
                                 ForwardIterator result,
                                 BinaryFunction binary_op,
                                 Predicate pred);
  
  
  /*! \} // end transformations
   */
  
  
  } // end namespace thrust
  
  #include <thrust/detail/transform.inl>
  
  