transform.hpp#

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

namespace hpx

Functions

template<typename ExPolicy, typename FwdIter1, typename FwdIter2, typename F> util::detail::algorithm_result<ExPolicy, util::in_out_result<FwdIter1, FwdIter2>>::type transform(ExPolicy &&policy, FwdIter1 first, FwdIter1 last, FwdIter2 dest, F &&f)#

Applies the given function f to the range [first, last) and stores the result in another range, beginning at dest.

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

Note

Complexity: Exactly last - first applications of f

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.
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 (deduced). This iterator type must meet the requirements of an forward iterator.
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.

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 – 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 an unary predicate. The signature of this predicate should be equivalent to:
```
Ret fun(const Type &a);
```
The signature does not need to have const&. The type Type must be such that an object of type FwdIter1 can be dereferenced and then implicitly converted to Type. The type Ret must be such that an object of type FwdIter2 can be dereferenced and assigned a value of type Ret.

Returns

The transform algorithm returns a hpx::future<in_out_result<FwdIter1, FwdIter2> > if the execution policy is of type parallel_task_policy and returns in_out_result<FwdIter1, FwdIter2> otherwise. The transform algorithm returns a tuple holding an iterator referring to the first element after the input sequence and the output iterator to the element in the destination range, one past the last element copied.

template<typename ExPolicy, typename FwdIter1, typename FwdIter2, typename FwdIter3, typename F> util::detail::algorithm_result<ExPolicy, util::in_in_out_result<FwdIter1, FwdIter2, FwdIter3>>::type transform(ExPolicy &&policy, FwdIter1 first1, FwdIter1 last1, FwdIter2 first2, FwdIter3 dest, F &&f)#

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.

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

Note

Complexity: Exactly last - first applications of f

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.
FwdIter1 – The type of the source iterators for the first range used (deduced). This iterator type must meet the requirements of an forward iterator.
FwdIter2 – The type of the source iterators for the second range used (deduced). This iterator type must meet the requirements of an forward iterator.
FwdIter3 – The type of the iterator representing the destination range (deduced). This iterator type must meet the requirements of an forward iterator.
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.

Parameters

policy – The execution policy to use for the scheduling of the iterations.
first1 – Refers to the beginning of the first 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.
first2 – Refers to the beginning of the second sequence of elements the algorithm will be applied to.
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 FwdIter1 and FwdIter2 can be dereferenced and then implicitly converted to Type1 and Type2 respectively. The type Ret must be such that an object of type FwdIter3 can be dereferenced and assigned a value of type Ret.

Returns

The transform algorithm returns a hpx::future<in_in_out_result<FwdIter1, FwdIter2, FwdIter3> > if the execution policy is of type parallel_task_policy and returns in_in_out_result<FwdIter1, FwdIter2, FwdIter3> otherwise. The transform algorithm returns a tuple holding an iterator referring to the first element after the first input sequence, an iterator referring to the first element after the second input sequence, and the output iterator referring to the element in the destination range, one past the last element copied.