hpx::ranges::transform_exclusive_scan#

Defined in header hpx/algorithm.hpp.

See Public API for a list of names and headers that are part of the public HPX API.

namespace hpx
namespace ranges

Functions

template<typename InIter, typename Sent, typename OutIter, typename BinOp, typename UnOp, typename T = typename std::iterator_traits<InIter>::value_type>
transform_exclusive_scan_result<InIter, OutIter> transform_exclusive_scan(InIter first, Sent last, OutIter dest, T init, BinOp &&binary_op, UnOp &&unary_op)#

Assigns through each iterator i in [result, result + (last - first)) the value of GENERALIZED_NONCOMMUTATIVE_SUM(binary_op, init, conv(*first), …, conv(*(first + (i - result) - 1))).

The reduce operations in the parallel transform_exclusive_scan algorithm invoked without an execution policy object execute in sequential order in the calling thread.

Neither conv nor op shall invalidate iterators or sub-ranges, or modify elements in the ranges [first,last) or [result,result + (last - first)).

The behavior of transform_exclusive_scan may be non-deterministic for a non-associative predicate.

Note

Complexity: O(last - first) applications of the predicates op and conv.

Note

GENERALIZED_NONCOMMUTATIVE_SUM(op, a1, …, aN) is defined as:

  • a1 when N is 1

  • op(GENERALIZED_NONCOMMUTATIVE_SUM(op, a1, …, aK), GENERALIZED_NONCOMMUTATIVE_SUM(op, aM, …, aN) where 1 < K+1 = M <= N.

Template Parameters
  • InIter – The type of the source iterators used (deduced). This iterator type must meet the requirements of an input iterator.

  • Sent – The type of the source sentinel (deduced). This sentinel type must be a sentinel for InIter.

  • OutIter – The type of the iterator representing the destination range (deduced). This iterator type must meet the requirements of an output iterator.

  • T – The type of the value to be used as initial (and intermediate) values (deduced).

  • BinOp – The type of the binary function object used for the reduction operation.

  • UnOp – The type of the unary function object used for the conversion operation.

Parameters
  • first – Refers to the beginning of the sequence of elements the algorithm will be applied to.

  • last – Refers to sentinel value denoting the end of the sequence of elements the algorithm will be applied.

  • dest – Refers to the beginning of the destination range.

  • init – The initial value for the generalized sum.

  • binary_op – Specifies the function (or function object) which will be invoked for each of the values of the input sequence. This is a binary predicate. The signature of this predicate should be equivalent to:

    Ret fun(const Type1 &a, const Type1 &b);
    
    The signature does not need to have const&, but the function must not modify the objects passed to it. The types Type1 and Ret must be such that an object of a type as given by the input sequence can be implicitly converted to any of those types.

  • unary_op – Specifies the function (or function object) which will be invoked for each of the elements in the sequence specified by [first, last). This is a unary predicate. The signature of this predicate should be equivalent to:

    R fun(const Type &a);
    
    The signature does not need to have const&, but the function must not modify the objects passed to it. The type Type must be such that an object of type FwdIter1 can be dereferenced and then implicitly converted to Type. The type R must be such that an object of this type can be implicitly converted to T.

Returns

The transform_exclusive_scan algorithm returns transform_exclusive_scan_result<InIter, OutIter>. The transform_exclusive_scan algorithm returns an input iterator to the point denoted by the sentinel and an output iterator to the element in the destination range, one past the last element copied.

template<typename ExPolicy, typename FwdIter1, typename Sent, typename FwdIter2, typename BinOp, typename UnOp, typename T = typename std::iterator_traits<FwdIter1>::value_type>
parallel::util::detail::algorithm_result<ExPolicy, transform_exclusive_result<FwdIter1, FwdIter2>>::type transform_exclusive_scan(ExPolicy &&policy, FwdIter1 first, Sent last, FwdIter2 dest, T init, BinOp &&binary_op, UnOp &&unary_op)#

Assigns through each iterator i in [result, result + (last - first)) the value of GENERALIZED_NONCOMMUTATIVE_SUM(binary_op, init, conv(*first), …, conv(*(first + (i - result) - 1))).

The reduce operations in the parallel transform_exclusive_scan algorithm invoked with an execution policy object of type sequenced_policy execute in sequential order in the calling thread.

The reduce operations in the parallel transform_exclusive_scan algorithm invoked with an execution policy object of type parallel_policy or parallel_task_policy are permitted to execute in an unordered fashion in unspecified threads, and indeterminately sequenced within each thread.

Neither conv nor op shall invalidate iterators or sub-ranges, or modify elements in the ranges [first,last) or [result,result + (last - first)).

The behavior of transform_exclusive_scan may be non-deterministic for a non-associative predicate.

Note

Complexity: O(last - first) applications of the predicates op and conv.

Note

GENERALIZED_NONCOMMUTATIVE_SUM(op, a1, …, aN) is defined as:

  • a1 when N is 1

  • op(GENERALIZED_NONCOMMUTATIVE_SUM(op, a1, …, aK), GENERALIZED_NONCOMMUTATIVE_SUM(op, aM, …, aN) where 1 < K+1 = M <= N.

Template Parameters
  • ExPolicy – The type of the execution policy to use (deduced). It describes the manner in which the execution of the algorithm may be parallelized and the manner in which it executes the assignments.

  • FwdIter1 – The type of the source iterators used (deduced). This iterator type must meet the requirements of an forward iterator.

  • Sent – The type of the source sentinel (deduced). This sentinel type must be a sentinel for FwdIter.

  • FwdIter2 – The type of the iterator representing the destination range (deduced). This iterator type must meet the requirements of an forward iterator.

  • T – The type of the value to be used as initial (and intermediate) values (deduced).

  • BinOp – The type of the binary function object used for the reduction operation.

  • UnOp – The type of the unary function object used for the conversion operation.

Parameters
  • policy – The execution policy to use for the scheduling of the iterations.

  • first – Refers to the beginning of the sequence of elements the algorithm will be applied to.

  • last – Refers to sentinel value denoting the end of the sequence of elements the algorithm will be applied.

  • dest – Refers to the beginning of the destination range.

  • init – The initial value for the generalized sum.

  • binary_op – Specifies the function (or function object) which will be invoked for each of the values of the input sequence. This is a binary predicate. The signature of this predicate should be equivalent to:

    Ret fun(const Type1 &a, const Type1 &b);
    
    The signature does not need to have const&, but the function must not modify the objects passed to it. The types Type1 and Ret must be such that an object of a type as given by the input sequence can be implicitly converted to any of those types.

  • unary_op – Specifies the function (or function object) which will be invoked for each of the elements in the sequence specified by [first, last). This is a unary predicate. The signature of this predicate should be equivalent to:

    R fun(const Type &a);
    
    The signature does not need to have const&, but the function must not modify the objects passed to it. The type Type must be such that an object of type FwdIter1 can be dereferenced and then implicitly converted to Type. The type R must be such that an object of this type can be implicitly converted to T.

Returns

The transform_exclusive_scan algorithm returns a hpx::future<transform_exclusive_result<FwdIter1, FwdIter2>> if the execution policy is of type sequenced_task_policy or parallel_task_policy and returns transform_exclusive_result<FwdIter1, FwdIter2> otherwise. The transform_exclusive_scan algorithm returns an input iterator to the point denoted by the sentinel and an output iterator to the element in the destination range, one past the last element copied.

template<typename Rng, typename O, typename BinOp, typename UnOp, typename T = typename std::iterator_traits<hpx::traits::range_iterator_t<Rng>>::value_type>
transform_exclusive_scan_result<hpx::traits::range_iterator_t<Rng>, O> transform_exclusive_scan(Rng &&rng, O dest, T init, BinOp &&binary_op, UnOp &&unary_op)#

Assigns through each iterator i in [result, result + (last - first)) the value of GENERALIZED_NONCOMMUTATIVE_SUM(binary_op, init, conv(*first), …, conv(*(first + (i - result) - 1))).

The reduce operations in the parallel transform_exclusive_scan algorithm invoked without an execution policy object execute in sequential order in the calling thread.

Neither conv nor op shall invalidate iterators or sub-ranges, or modify elements in the ranges [first,last) or [result,result + (last - first)).

The behavior of transform_exclusive_scan may be non-deterministic for a non-associative predicate.

Note

Complexity: O(last - first) applications of the predicates op and conv.

Note

GENERALIZED_NONCOMMUTATIVE_SUM(op, a1, …, aN) is defined as:

  • a1 when N is 1

  • op(GENERALIZED_NONCOMMUTATIVE_SUM(op, a1, …, aK), GENERALIZED_NONCOMMUTATIVE_SUM(op, aM, …, aN) where 1 < K+1 = M <= N.

Template Parameters
  • Rng – The type of the source range used (deduced). The iterators extracted from this range type must meet the requirements of an input iterator.

  • O – The type of the iterator representing the destination range (deduced).

  • T – The type of the value to be used as initial (and intermediate) values (deduced).

  • BinOp – The type of the binary function object used for the reduction operation.

  • UnOp – The type of the unary function object used for the conversion operation.

Parameters
  • rng – Refers to the sequence of elements the algorithm will be applied to.

  • dest – Refers to the beginning of the destination range.

  • init – The initial value for the generalized sum.

  • binary_op – Specifies the function (or function object) which will be invoked for each of the values of the input sequence. This is a binary predicate. The signature of this predicate should be equivalent to:

    Ret fun(const Type1 &a, const Type1 &b);
    
    The signature does not need to have const&, but the function must not modify the objects passed to it. The types Type1 and Ret must be such that an object of a type as given by the input sequence can be implicitly converted to any of those types.

  • unary_op – Specifies the function (or function object) which will be invoked for each of the elements in the sequence specified by [first, last). This is a unary predicate. The signature of this predicate should be equivalent to:

    R fun(const Type &a);
    
    The signature does not need to have const&, but the function must not modify the objects passed to it. The type Type must be such that an object of type FwdIter1 can be dereferenced and then implicitly converted to Type. The type R must be such that an object of this type can be implicitly converted to T.

Returns

The transform_exclusive_scan algorithm returns a returns transform_exclusive_scan_result< traits::range_iterator_t<Rng>, O>. The transform_exclusive_scan algorithm returns an input iterator to one past the end of the range and an output iterator to the element in the destination range, one past the last element copied.

template<typename ExPolicy, typename Rng, typename O, typename BinOp, typename UnOp, typename T = typename std::iterator_traits<hpx::traits::range_iterator_t<Rng>>::value_type>
parallel::util::detail::algorithm_result<ExPolicy, transform_exclusive_scan_result<hpx::traits::range_iterator_t<Rng>, O>>::type transform_exclusive_scan(ExPolicy &&policy, Rng &&rng, O dest, T init, BinOp &&binary_op, UnOp &&unary_op)#

Assigns through each iterator i in [result, result + (last - first)) the value of GENERALIZED_NONCOMMUTATIVE_SUM(binary_op, init, conv(*first), …, conv(*(first + (i - result) - 1))).

The reduce operations in the parallel transform_exclusive_scan algorithm invoked with an execution policy object of type sequenced_policy execute in sequential order in the calling thread.

The reduce operations in the parallel transform_exclusive_scan algorithm invoked with an execution policy object of type parallel_policy or parallel_task_policy are permitted to execute in an unordered fashion in unspecified threads, and indeterminately sequenced within each thread.

Neither conv nor op shall invalidate iterators or sub-ranges, or modify elements in the ranges [first,last) or [result,result + (last - first)).

The behavior of transform_exclusive_scan may be non-deterministic for a non-associative predicate.

Note

Complexity: O(last - first) applications of the predicates op and conv.

Note

GENERALIZED_NONCOMMUTATIVE_SUM(op, a1, …, aN) is defined as:

  • a1 when N is 1

  • op(GENERALIZED_NONCOMMUTATIVE_SUM(op, a1, …, aK), GENERALIZED_NONCOMMUTATIVE_SUM(op, aM, …, aN) where 1 < K+1 = M <= N.

Template Parameters
  • ExPolicy – The type of the execution policy to use (deduced). It describes the manner in which the execution of the algorithm may be parallelized and the manner in which it executes the assignments.

  • Rng – The type of the source range used (deduced). The iterators extracted from this range type must meet the requirements of an forward iterator.

  • O – The type of the iterator representing the destination range (deduced). This iterator type must meet the requirements of an forward iterator. This iterator type must meet the requirements of an forward iterator.

  • T – The type of the value to be used as initial (and intermediate) values (deduced).

  • BinOp – The type of the binary function object used for the reduction operation.

  • UnOp – The type of the unary function object used for the conversion operation.

Parameters
  • policy – The execution policy to use for the scheduling of the iterations.

  • rng – Refers to the sequence of elements the algorithm will be applied to.

  • dest – Refers to the beginning of the destination range.

  • init – The initial value for the generalized sum.

  • binary_op – Specifies the function (or function object) which will be invoked for each of the values of the input sequence. This is a binary predicate. The signature of this predicate should be equivalent to:

    Ret fun(const Type1 &a, const Type1 &b);
    
    The signature does not need to have const&, but the function must not modify the objects passed to it. The types Type1 and Ret must be such that an object of a type as given by the input sequence can be implicitly converted to any of those types.

  • unary_op – Specifies the function (or function object) which will be invoked for each of the elements in the sequence specified by [first, last). This is a unary predicate. The signature of this predicate should be equivalent to:

    R fun(const Type &a);
    
    The signature does not need to have const&, but the function must not modify the objects passed to it. The type Type must be such that an object of type FwdIter1 can be dereferenced and then implicitly converted to Type. The type R must be such that an object of this type can be implicitly converted to T.

Returns

The transform_exclusive_scan algorithm returns a hpx::future<transform_exclusive_scan_result< traits::range_iterator_t<Rng>, O>> if the execution policy is of type sequenced_task_policy or parallel_task_policy and returns transform_exclusive_scan_result< traits::range_iterator_t<Rng>, O> otherwise. The transform_exclusive_scan algorithm returns an input iterator to one past the end of the range and an output iterator to the element in the destination range, one past the last element copied.