hpx::partition_copy

hpx::partition_copy#

Defined in header hpx/algorithm.hpp.

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

See also:

template<typename FwdIter1, typename FwdIter2, typename FwdIter3, typename Pred, typename Proj = hpx::identity>
std::pair<FwdIter2, FwdIter3> hpx::partition_copy(FwdIter1 first, FwdIter1 last, FwdIter2 dest_true, FwdIter3 dest_false, Pred &&pred, Proj &&proj = Proj())#

Copies the elements in the range, defined by [first, last), to two different ranges depending on the value returned by the predicate pred. The elements, that satisfy the predicate pred are copied to the range beginning at dest_true. The rest of the elements are copied to the range beginning at dest_false. The order of the elements is preserved.

The assignments in the parallel partition_copy algorithm invoked without an execution policy object execute in sequential order in the calling thread.

Note

Complexity: Performs not more than last - first assignments, exactly last - first applications of the predicate pred.

Template Parameters:

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

  • FwdIter2 – The type of the iterator representing the destination range for the elements that satisfy the predicate pred (deduced). This iterator type must meet the requirements of an forward iterator.

  • FwdIter3 – The type of the iterator representing the destination range for the elements that don’t satisfy the predicate pred (deduced). This iterator type must meet the requirements of an forward iterator.

  • Pred – The type of the function/function object to use (deduced). Unlike its sequential form, the parallel overload of partition_copy requires Pred to meet the requirements of CopyConstructible.

  • Proj – The type of an optional projection function. This defaults to hpx::identity

Parameters:

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

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

  • dest_true – Refers to the beginning of the destination range for the elements that satisfy the predicate pred

  • dest_false – Refers to the beginning of the destination range for the elements that don’t satisfy the predicate pred.

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

    bool pred(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.

  • proj – Specifies the function (or function object) which will be invoked for each of the elements as a projection operation before the actual predicate is invoked.

Returns:

The partition_copy algorithm returns std::pair<OutIter1, OutIter2>. The partition_copy algorithm returns the pair of the destination iterator to the end of the dest_true range, and the destination iterator to the end of the dest_false range.

template<typename ExPolicy, typename FwdIter1, typename FwdIter2, typename FwdIter3, typename Pred, typename Proj = hpx::identity>
parallel::util::detail::algorithm_result_t<ExPolicy, std::pair<FwdIter2, FwdIter3>> hpx::partition_copy(ExPolicy &&policy, FwdIter1 first, FwdIter1 last, FwdIter2 dest_true, FwdIter3 dest_false, Pred &&pred, Proj &&proj = Proj())#

Copies the elements in the range, defined by [first, last), to two different ranges depending on the value returned by the predicate pred. The elements, that satisfy the predicate pred, are copied to the range beginning at dest_true. The rest of the elements are copied to the range beginning at dest_false. The order of the elements is preserved.

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

The assignments in the parallel partition_copy 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.

Note

Complexity: Performs not more than last - first assignments, exactly last - first applications of the predicate pred.

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.

  • FwdIter2 – The type of the iterator representing the destination range for the elements that satisfy the predicate pred (deduced). This iterator type must meet the requirements of an forward iterator.

  • FwdIter3 – The type of the iterator representing the destination range for the elements that don’t satisfy the predicate pred (deduced). This iterator type must meet the requirements of an forward iterator.

  • Pred – The type of the function/function object to use (deduced). Unlike its sequential form, the parallel overload of partition_copy requires Pred to meet the requirements of CopyConstructible.

  • Proj – The type of an optional projection function. This defaults to hpx::identity

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 the end of the sequence of elements the algorithm will be applied to.

  • dest_true – Refers to the beginning of the destination range for the elements that satisfy the predicate pred

  • dest_false – Refers to the beginning of the destination range for the elements that don’t satisfy the predicate pred.

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

    bool pred(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.

  • proj – Specifies the function (or function object) which will be invoked for each of the elements as a projection operation before the actual predicate is invoked.

Returns:

The partition_copy algorithm returns a hpx::future<std::pair<OutIter1, OutIter2>> if the execution policy is of type parallel_task_policy and returns std::pair<OutIter1, OutIter2> otherwise. The partition_copy algorithm returns the pair of the destination iterator to the end of the dest_true range, and the destination iterator to the end of the dest_false range.

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