hpx/parallel/algorithms/for_loop.hpp
hpx/parallel/algorithms/for_loop.hpp#
See Public API for a list of names and headers that are part of the public HPX API.

namespace hpx

namespace experimental#
Functions

template<typename I, typename ...Args>
void for_loop(std::decay_t<I> first, I last, Args&&... args)# The for_loop implements loop functionality over a range specified by integral or iterator bounds. For the iterator case, these algorithms resemble for_each from the Parallelism TS, but leave to the programmer when and if to dereference the iterator.
The execution of for_loop without specifying an execution policy is equivalent to specifying hpx::execution::seq as the execution policy.
Requires: I shall be an integral type or meet the requirements of an input iterator type. The args parameter pack shall have at least one element, comprising objects returned by invocations of reduction and/or induction function templates followed by exactly one element invocable elementaccess function, f. f shall meet the requirements of MoveConstructible.
Effects: Applies f to each element in the input sequence, with additional arguments corresponding to the reductions and inductions in the args parameter pack. The length of the input sequence is last  first.
The first element in the input sequence is specified by first. Each subsequent element is generated by incrementing the previous element.
Along with an element from the input sequence, for each member of the args parameter pack excluding f, an additional argument is passed to each application of f as follows:
If the pack member is an object returned by a call to a reduction function listed in section, then the additional argument is a reference to a view of that reduction object. If the pack member is an object returned by a call to induction, then the additional argument is the induction value for that induction object corresponding to the position of the application of f in the input sequence.
Complexity: Applies f exactly once for each element of the input sequence.
Remarks: If f returns a result, the result is ignored.
Note
As described in the C++ standard, arithmetic on nonrandomaccess iterators is performed using advance and distance.
Note
The order of the elements of the input sequence is important for determining ordinal position of an application of f, even though the applications themselves may be unordered.
 Template Parameters
I – The type of the iteration variable. This could be an (forward) iterator type or an integral type.
Args – A parameter pack, it’s last element is a function object to be invoked for each iteration, the others have to be either conforming to the induction or reduction concept.
 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.
args – The last element of this parameter pack is the function (object) to invoke, while the remaining elements of the parameter pack are instances of either induction or reduction objects. The function (or function object) which will be invoked for each of the elements in the sequence specified by [first, last) should expose a signature equivalent to:
The signature does not need to have const&. It will receive the current value of the iteration variable and one argument for each of the induction or reduction objects passed to the algorithms, representing their current values.<ignored> pred(I const& a, ...);

template<typename ExPolicy, typename I, typename ...Args>
util::detail::algorithm_result<ExPolicy>::type for_loop(ExPolicy &&policy, std::decay_t<I> first, I last, Args&&... args)# The for_loop implements loop functionality over a range specified by integral or iterator bounds. For the iterator case, these algorithms resemble for_each from the Parallelism TS, but leave to the programmer when and if to dereference the iterator. Executed according to the policy.
Requires: I shall be an integral type or meet the requirements of an input iterator type. The args parameter pack shall have at least one element, comprising objects returned by invocations of reduction and/or induction function templates followed by exactly one element invocable elementaccess function, f. f shall meet the requirements of MoveConstructible.
Effects: Applies f to each element in the input sequence, with additional arguments corresponding to the reductions and inductions in the args parameter pack. The length of the input sequence is last  first.
The first element in the input sequence is specified by first. Each subsequent element is generated by incrementing the previous element.
Along with an element from the input sequence, for each member of the args parameter pack excluding f, an additional argument is passed to each application of f as follows:
If the pack member is an object returned by a call to a reduction function listed in section, then the additional argument is a reference to a view of that reduction object. If the pack member is an object returned by a call to induction, then the additional argument is the induction value for that induction object corresponding to the position of the application of f in the input sequence.
Complexity: Applies f exactly once for each element of the input sequence.
Remarks: If f returns a result, the result is ignored.
Note
As described in the C++ standard, arithmetic on nonrandomaccess iterators is performed using advance and distance.
Note
The order of the elements of the input sequence is important for determining ordinal position of an application of f, even though the applications themselves may be unordered.
 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 applies userprovided function objects.
I – The type of the iteration variable. This could be an (forward) iterator type or an integral type.
Args – A parameter pack, it’s last element is a function object to be invoked for each iteration, the others have to be either conforming to the induction or reduction concept.
 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.
args – The last element of this parameter pack is the function (object) to invoke, while the remaining elements of the parameter pack are instances of either induction or reduction objects. The function (or function object) which will be invoked for each of the elements in the sequence specified by [first, last) should expose a signature equivalent to:
The signature does not need to have const&. It will receive the current value of the iteration variable and one argument for each of the induction or reduction objects passed to the algorithms, representing their current values.<ignored> pred(I const& a, ...);
 Returns
The for_loop algorithm returns a hpx::future<void> if the execution policy is of type hpx::execution::sequenced_task_policy or hpx::execution::parallel_task_policy and returns void otherwise.

template<typename I, typename S, typename ...Args>
void for_loop_strided(std::decay_t<I> first, I last, S stride, Args&&... args)# The for_loop_strided implements loop functionality over a range specified by integral or iterator bounds. For the iterator case, these algorithms resemble for_each from the Parallelism TS, but leave to the programmer when and if to dereference the iterator.
The execution of for_loop without specifying an execution policy is equivalent to specifying hpx::execution::seq as the execution policy.
Requires: I shall be an integral type or meet the requirements of an input iterator type. The args parameter pack shall have at least one element, comprising objects returned by invocations of reduction and/or induction function templates followed by exactly one element invocable elementaccess function, f. f shall meet the requirements of MoveConstructible.
Effects: Applies f to each element in the input sequence, with additional arguments corresponding to the reductions and inductions in the args parameter pack. The length of the input sequence is last  first.
The first element in the input sequence is specified by first. Each subsequent element is generated by incrementing the previous element.
Along with an element from the input sequence, for each member of the args parameter pack excluding f, an additional argument is passed to each application of f as follows:
If the pack member is an object returned by a call to a reduction function listed in section, then the additional argument is a reference to a view of that reduction object. If the pack member is an object returned by a call to induction, then the additional argument is the induction value for that induction object corresponding to the position of the application of f in the input sequence.
Complexity: Applies f exactly once for each element of the input sequence.
Remarks: If f returns a result, the result is ignored.
Note
As described in the C++ standard, arithmetic on nonrandomaccess iterators is performed using advance and distance.
Note
The order of the elements of the input sequence is important for determining ordinal position of an application of f, even though the applications themselves may be unordered.
 Template Parameters
I – The type of the iteration variable. This could be an (forward) iterator type or an integral type.
S – The type of the stride variable. This should be an integral type.
Args – A parameter pack, it’s last element is a function object to be invoked for each iteration, the others have to be either conforming to the induction or reduction concept.
 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.
stride – Refers to the stride of the iteration steps. This shall have nonzero value and shall be negative only if I has integral type or meets the requirements of a bidirectional iterator.
args – The last element of this parameter pack is the function (object) to invoke, while the remaining elements of the parameter pack are instances of either induction or reduction objects. The function (or function object) which will be invoked for each of the elements in the sequence specified by [first, last) should expose a signature equivalent to:
The signature does not need to have const&. It will receive the current value of the iteration variable and one argument for each of the induction or reduction objects passed to the algorithms, representing their current values.<ignored> pred(I const& a, ...);

template<typename ExPolicy, typename I, typename S, typename ...Args>
util::detail::algorithm_result<ExPolicy>::type for_loop_strided(ExPolicy &&policy, std::decay_t<I> first, I last, S stride, Args&&... args)# The for_loop_strided implements loop functionality over a range specified by integral or iterator bounds. For the iterator case, these algorithms resemble for_each from the Parallelism TS, but leave to the programmer when and if to dereference the iterator. Executed according to the policy.
Requires: I shall be an integral type or meet the requirements of an input iterator type. The args parameter pack shall have at least one element, comprising objects returned by invocations of reduction and/or induction function templates followed by exactly one element invocable elementaccess function, f. f shall meet the requirements of MoveConstructible.
Effects: Applies f to each element in the input sequence, with additional arguments corresponding to the reductions and inductions in the args parameter pack. The length of the input sequence is last  first.
The first element in the input sequence is specified by first. Each subsequent element is generated by incrementing the previous element.
Along with an element from the input sequence, for each member of the args parameter pack excluding f, an additional argument is passed to each application of f as follows:
If the pack member is an object returned by a call to a reduction function listed in section, then the additional argument is a reference to a view of that reduction object. If the pack member is an object returned by a call to induction, then the additional argument is the induction value for that induction object corresponding to the position of the application of f in the input sequence.
Complexity: Applies f exactly once for each element of the input sequence.
Remarks: If f returns a result, the result is ignored.
Note
As described in the C++ standard, arithmetic on nonrandomaccess iterators is performed using advance and distance.
Note
The order of the elements of the input sequence is important for determining ordinal position of an application of f, even though the applications themselves may be unordered.
 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 applies userprovided function objects.
I – The type of the iteration variable. This could be an (forward) iterator type or an integral type.
S – The type of the stride variable. This should be an integral type.
Args – A parameter pack, it’s last element is a function object to be invoked for each iteration, the others have to be either conforming to the induction or reduction concept.
 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.
stride – Refers to the stride of the iteration steps. This shall have nonzero value and shall be negative only if I has integral type or meets the requirements of a bidirectional iterator.
args – The last element of this parameter pack is the function (object) to invoke, while the remaining elements of the parameter pack are instances of either induction or reduction objects. The function (or function object) which will be invoked for each of the elements in the sequence specified by [first, last) should expose a signature equivalent to:
The signature does not need to have const&. It will receive the current value of the iteration variable and one argument for each of the induction or reduction objects passed to the algorithms, representing their current values.<ignored> pred(I const& a, ...);
 Returns
The for_loop_strided algorithm returns a hpx::future<void> if the execution policy is of type hpx::execution::sequenced_task_policy or hpx::execution::parallel_task_policy and returns void otherwise.

template<typename I, typename Size, typename ...Args>
void for_loop_n(I first, Size size, Args&&... args)# The for_loop_n implements loop functionality over a range specified by integral or iterator bounds. For the iterator case, these algorithms resemble for_each from the Parallelism TS, but leave to the programmer when and if to dereference the iterator.
The execution of for_loop_n without specifying an execution policy is equivalent to specifying hpx::execution::seq as the execution policy.
Requires: I shall be an integral type or meet the requirements of an input iterator type. The args parameter pack shall have at least one element, comprising objects returned by invocations of reduction and/or induction function templates followed by exactly one element invocable elementaccess function, f. f shall meet the requirements of MoveConstructible.
Effects: Applies f to each element in the input sequence, with additional arguments corresponding to the reductions and inductions in the args parameter pack. The length of the input sequence is last  first.
The first element in the input sequence is specified by first. Each subsequent element is generated by incrementing the previous element.
Along with an element from the input sequence, for each member of the args parameter pack excluding f, an additional argument is passed to each application of f as follows:
If the pack member is an object returned by a call to a reduction function listed in section, then the additional argument is a reference to a view of that reduction object. If the pack member is an object returned by a call to induction, then the additional argument is the induction value for that induction object corresponding to the position of the application of f in the input sequence.
Complexity: Applies f exactly once for each element of the input sequence.
Remarks: If f returns a result, the result is ignored.
Note
As described in the C++ standard, arithmetic on nonrandomaccess iterators is performed using advance and distance.
Note
The order of the elements of the input sequence is important for determining ordinal position of an application of f, even though the applications themselves may be unordered.
 Template Parameters
I – The type of the iteration variable. This could be an (forward) iterator type or an integral type.
Size – The type of a nonnegative integral value specifying the number of items to iterate over.
Args – A parameter pack, it’s last element is a function object to be invoked for each iteration, the others have to be either conforming to the induction or reduction concept.
 Parameters
first – Refers to the beginning of the sequence of elements the algorithm will be applied to.
size – Refers to the number of items the algorithm will be applied to.
args – The last element of this parameter pack is the function (object) to invoke, while the remaining elements of the parameter pack are instances of either induction or reduction objects. The function (or function object) which will be invoked for each of the elements in the sequence specified by [first, last) should expose a signature equivalent to:
The signature does not need to have const&. It will receive the current value of the iteration variable and one argument for each of the induction or reduction objects passed to the algorithms, representing their current values.<ignored> pred(I const& a, ...);

template<typename ExPolicy, typename I, typename Size, typename ...Args>
util::detail::algorithm_result<ExPolicy>::type for_loop_n(ExPolicy &&policy, I first, Size size, Args&&... args)# The for_loop_n implements loop functionality over a range specified by integral or iterator bounds. For the iterator case, these algorithms resemble for_each from the Parallelism TS, but leave to the programmer when and if to dereference the iterator. Executed according to the policy.
Requires: I shall be an integral type or meet the requirements of an input iterator type. The args parameter pack shall have at least one element, comprising objects returned by invocations of reduction and/or induction function templates followed by exactly one element invocable elementaccess function, f. f shall meet the requirements of MoveConstructible.
Effects: Applies f to each element in the input sequence, with additional arguments corresponding to the reductions and inductions in the args parameter pack. The length of the input sequence is last  first.
The first element in the input sequence is specified by first. Each subsequent element is generated by incrementing the previous element.
Along with an element from the input sequence, for each member of the args parameter pack excluding f, an additional argument is passed to each application of f as follows:
If the pack member is an object returned by a call to a reduction function listed in section, then the additional argument is a reference to a view of that reduction object. If the pack member is an object returned by a call to induction, then the additional argument is the induction value for that induction object corresponding to the position of the application of f in the input sequence.
Complexity: Applies f exactly once for each element of the input sequence.
Remarks: If f returns a result, the result is ignored.
Note
As described in the C++ standard, arithmetic on nonrandomaccess iterators is performed using advance and distance.
Note
The order of the elements of the input sequence is important for determining ordinal position of an application of f, even though the applications themselves may be unordered.
 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 applies userprovided function objects.
I – The type of the iteration variable. This could be an (forward) iterator type or an integral type.
Size – The type of a nonnegative integral value specifying the number of items to iterate over.
Args – A parameter pack, it’s last element is a function object to be invoked for each iteration, the others have to be either conforming to the induction or reduction concept.
 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.
size – Refers to the number of items the algorithm will be applied to.
args – The last element of this parameter pack is the function (object) to invoke, while the remaining elements of the parameter pack are instances of either induction or reduction objects. The function (or function object) which will be invoked for each of the elements in the sequence specified by [first, last) should expose a signature equivalent to:
The signature does not need to have const&. It will receive the current value of the iteration variable and one argument for each of the induction or reduction objects passed to the algorithms, representing their current values.<ignored> pred(I const& a, ...);
 Returns
The for_loop_n algorithm returns a hpx::future<void> if the execution policy is of type hpx::execution::sequenced_task_policy or hpx::execution::parallel_task_policy and returns void otherwise.

template<typename I, typename Size, typename S, typename ...Args>
void for_loop_n_strided(I first, Size size, S stride, Args&&... args)# The for_loop_n_strided implements loop functionality over a range specified by integral or iterator bounds. For the iterator case, these algorithms resemble for_each from the Parallelism TS, but leave to the programmer when and if to dereference the iterator.
The execution of for_loop without specifying an execution policy is equivalent to specifying hpx::execution::seq as the execution policy.
Requires: I shall be an integral type or meet the requirements of an input iterator type. The args parameter pack shall have at least one element, comprising objects returned by invocations of reduction and/or induction function templates followed by exactly one element invocable elementaccess function, f. f shall meet the requirements of MoveConstructible.
Effects: Applies f to each element in the input sequence, with additional arguments corresponding to the reductions and inductions in the args parameter pack. The length of the input sequence is last  first.
The first element in the input sequence is specified by first. Each subsequent element is generated by incrementing the previous element.
Along with an element from the input sequence, for each member of the args parameter pack excluding f, an additional argument is passed to each application of f as follows:
If the pack member is an object returned by a call to a reduction function listed in section, then the additional argument is a reference to a view of that reduction object. If the pack member is an object returned by a call to induction, then the additional argument is the induction value for that induction object corresponding to the position of the application of f in the input sequence.
Complexity: Applies f exactly once for each element of the input sequence.
Remarks: If f returns a result, the result is ignored.
Note
As described in the C++ standard, arithmetic on nonrandomaccess iterators is performed using advance and distance.
Note
The order of the elements of the input sequence is important for determining ordinal position of an application of f, even though the applications themselves may be unordered.
 Template Parameters
I – The type of the iteration variable. This could be an (forward) iterator type or an integral type.
Size – The type of a nonnegative integral value specifying the number of items to iterate over.
S – The type of the stride variable. This should be an integral type.
Args – A parameter pack, it’s last element is a function object to be invoked for each iteration, the others have to be either conforming to the induction or reduction concept.
 Parameters
first – Refers to the beginning of the sequence of elements the algorithm will be applied to.
size – Refers to the number of items the algorithm will be applied to.
stride – Refers to the stride of the iteration steps. This shall have nonzero value and shall be negative only if I has integral type or meets the requirements of a bidirectional iterator.
args – The last element of this parameter pack is the function (object) to invoke, while the remaining elements of the parameter pack are instances of either induction or reduction objects. The function (or function object) which will be invoked for each of the elements in the sequence specified by [first, last) should expose a signature equivalent to:
The signature does not need to have const&. It will receive the current value of the iteration variable and one argument for each of the induction or reduction objects passed to the algorithms, representing their current values.<ignored> pred(I const& a, ...);

template<typename ExPolicy, typename I, typename Size, typename S, typename ...Args>
util::detail::algorithm_result<ExPolicy>::type for_loop_n_strided(ExPolicy &&policy, I first, Size size, S stride, Args&&... args)# The for_loop_n_strided implements loop functionality over a range specified by integral or iterator bounds. For the iterator case, these algorithms resemble for_each from the Parallelism TS, but leave to the programmer when and if to dereference the iterator. Executed according to the policy.
Requires: I shall be an integral type or meet the requirements of an input iterator type. The args parameter pack shall have at least one element, comprising objects returned by invocations of reduction and/or induction function templates followed by exactly one element invocable elementaccess function, f. f shall meet the requirements of MoveConstructible.
Effects: Applies f to each element in the input sequence, with additional arguments corresponding to the reductions and inductions in the args parameter pack. The length of the input sequence is last  first.
The first element in the input sequence is specified by first. Each subsequent element is generated by incrementing the previous element.
Along with an element from the input sequence, for each member of the args parameter pack excluding f, an additional argument is passed to each application of f as follows:
If the pack member is an object returned by a call to a reduction function listed in section, then the additional argument is a reference to a view of that reduction object. If the pack member is an object returned by a call to induction, then the additional argument is the induction value for that induction object corresponding to the position of the application of f in the input sequence.
Complexity: Applies f exactly once for each element of the input sequence.
Remarks: If f returns a result, the result is ignored.
Note
As described in the C++ standard, arithmetic on nonrandomaccess iterators is performed using advance and distance.
Note
The order of the elements of the input sequence is important for determining ordinal position of an application of f, even though the applications themselves may be unordered.
 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 applies userprovided function objects.
I – The type of the iteration variable. This could be an (forward) iterator type or an integral type.
Size – The type of a nonnegative integral value specifying the number of items to iterate over.
S – The type of the stride variable. This should be an integral type.
Args – A parameter pack, it’s last element is a function object to be invoked for each iteration, the others have to be either conforming to the induction or reduction concept.
 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.
size – Refers to the number of items the algorithm will be applied to.
stride – Refers to the stride of the iteration steps. This shall have nonzero value and shall be negative only if I has integral type or meets the requirements of a bidirectional iterator.
args – The last element of this parameter pack is the function (object) to invoke, while the remaining elements of the parameter pack are instances of either induction or reduction objects. The function (or function object) which will be invoked for each of the elements in the sequence specified by [first, last) should expose a signature equivalent to:
The signature does not need to have const&. It will receive the current value of the iteration variable and one argument for each of the induction or reduction objects passed to the algorithms, representing their current values.<ignored> pred(I const& a, ...);
 Returns
The for_loop_n_strided algorithm returns a hpx::future<void> if the execution policy is of type hpx::execution::sequenced_task_policy or hpx::execution::parallel_task_policy and returns void otherwise.

template<typename I, typename ...Args>

namespace experimental#