Function template transform

hpx::parallel::v1::transform

Synopsis

// In header: <hpx/parallel/detail/transform.hpp>


template<typename ExPolicy, typename InIter1, typename InIter2, 
         typename OutIter, typename F> 
  unspecified transform(ExPolicy && policy, InIter1 first1, InIter1 last1, 
                        InIter2 first2, OutIter dest, F && f);

Description

Applies the given function f to pairs of elements from two ranges: one defined by [first1, last1) and the other beginning at first2, and stores the result in another range, beginning at dest.

	Note
	Complexity: Exactly last - first applications of f

The invocations of f in the parallel transform algorithm invoked with an execution policy object of type sequential_execution_policy execute in sequential order in the calling thread.

The invocations of f in the parallel transform algorithm invoked with an execution policy object of type parallel_execution_policy or task_execution_policy are permitted to execute in an unordered fashion in unspecified threads, and indeterminately sequenced within each thread.

Parameters:

`dest`	Refers to the beginning of the destination range.
`f`	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 binary predicate. The signature of this predicate should be equivalent to: Ret fun(const Type1 &a, const Type2 &b); The signature does not need to have const&. The types Type1 and Type2 must be such that objects of types InIter1 and InIter2 can be dereferenced and then implicitly converted to Type1 and Type2 respectively. The type Ret must be such that an object of type OutIter can be dereferenced and assigned a value of type Ret.
`first1`	Refers to the beginning of the first sequence of elements the algorithm will be applied to.
`first2`	Refers to the beginning of the second sequence of elements the algorithm will be applied to.
`last1`	Refers to the end of the first sequence of elements the algorithm will be applied to.
`policy`	The execution policy to use for the scheduling of the iterations.

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 invocations of f.
`F`	The type of the function/function object to use (deduced). Unlike its sequential form, the parallel overload of transform requires F to meet the requirements of CopyConstructible.
`InIter1`	The type of the source iterators for the first range used (deduced). This iterator type must meet the requirements of an input iterator.
`InIter2`	The type of the source iterators for the second range used (deduced). This iterator type must meet the requirements of an input iterator.
`OutIter`	The type of the iterator representing the destination range (deduced). This iterator type must meet the requirements of an output iterator.

Returns:

The transform algorithm returns a hpx::future<OutIter> if the execution policy is of type task_execution_policy and returns OutIter otherwise. The transform algorithm returns the output iterator to the element in the destination range, one past the last element copied.