hpx::search

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:

• hpx::search_n

template<typename FwdIter, typename FwdIter2, typename Pred = parallel::detail::equal_to>
FwdIter hpx::search(FwdIter first, FwdIter last, FwdIter2 s_first, FwdIter2 s_last, Pred &&op = Pred())

Searches the range [first, last) for any elements in the range [s_first, s_last). Uses a provided predicate to compare elements.

The comparison operations in the parallel search algorithm execute in sequential order in the calling thread.

Note

Complexity: at most (S*N) comparisons where S = distance(s_first, s_last) and N = distance(first, last).

Template Parameters:

• FwdIter – The type of the source iterators used for the first range (deduced). This iterator type must meet the requirements of a forward iterator.

• FwdIter2 – The type of the source iterators used for the second range (deduced). This iterator type must meet the requirements of a forward iterator.

• Pred – The type of an optional function/function object to use. Unlike its sequential form, the parallel overload of search requires Pred to meet the requirements of CopyConstructible. This defaults to std::equal_to<>

Parameters:

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

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

• s_first – Refers to the beginning of the sequence of elements the algorithm will be searching for.

• s_last – Refers to the end of the sequence of elements of the algorithm will be searching for.

• op – Refers to the binary predicate which returns true if the elements should be treated as equal. the signature of the function should be equivalent to

  bool pred(const Type1 &a, const Type2 &b);
  

  The signature does not need to have const &, but the function must not modify the objects passed to it. 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

Returns:

The search algorithm returns a hpx::future<FwdIter> if the execution policy is of type task_execution_policy and returns FwdIter otherwise. The search algorithm returns an iterator to the beginning of the first subsequence [s_first, s_last) in range [first, last). If the length of the subsequence [s_first, s_last) is greater than the length of the range [first, last), last is returned. Additionally if the size of the subsequence is empty first is returned. If no subsequence is found, last is returned.

template<typename ExPolicy, typename FwdIter, typename FwdIter2, typename Pred = parallel::detail::equal_to>
hpx::parallel::util::detail::algorithm_result_t<ExPolicy, FwdIter> hpx::search(ExPolicy &&policy, FwdIter first, FwdIter last, FwdIter2 s_first, FwdIter2 s_last, Pred &&op = Pred())

Searches the range [first, last) for any elements in the range [s_first, s_last). Uses a provided predicate to compare elements. Executed according to the policy.

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

The comparison operations in the parallel search 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: at most (S*N) comparisons where S = distance(s_first, s_last) and N = distance(first, last).

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.

• FwdIter – The type of the source iterators used for the first range (deduced). This iterator type must meet the requirements of a forward iterator.

• FwdIter2 – The type of the source iterators used for the second range (deduced). This iterator type must meet the requirements of a forward iterator.

• Pred – The type of an optional function/function object to use. Unlike its sequential form, the parallel overload of search requires Pred to meet the requirements of CopyConstructible. This defaults to std::equal_to<>.

Parameters:

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

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

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

• s_first – Refers to the beginning of the sequence of elements the algorithm will be searching for.

• s_last – Refers to the end of the sequence of elements of the algorithm will be searching for.

• op – Refers to the binary predicate which returns true if the elements should be treated as equal. the signature of the function should be equivalent to

  bool pred(const Type1 &a, const Type2 &b);
  

  The signature does not need to have const &, but the function must not modify the objects passed to it. 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

Returns:

The search algorithm returns a hpx::future<FwdIter> if the execution policy is of type task_execution_policy and returns FwdIter otherwise. The search algorithm returns an iterator to the beginning of the first subsequence [s_first, s_last) in range [first, last). If the length of the subsequence [s_first, s_last) is greater than the length of the range [first, last), last is returned. Additionally if the size of the subsequence is empty first is returned. If no subsequence is found, last is returned.

template<typename FwdIter, typename Searcher>
FwdIter hpx::search(FwdIter first, FwdIter last, Searcher &&searcher)

Searches the range [first, last) using a searcher object.

Template Parameters:

• FwdIter – The type of the source iterators (deduced). This iterator type must meet the requirements of a forward iterator.

• Searcher – A callable searcher object meeting the C++ Searcher requirements (e.g. std::boyer_moore_searcher).

Parameters:

• first – Refers to the beginning of the sequence to search.

• last – Refers to the end of the sequence to search.

• searcher – A callable object performing the search.

Returns:

An iterator to the beginning of the found subsequence, or last if no subsequence is found.

template<typename ExPolicy, typename FwdIter, typename Searcher>
hpx::parallel::util::detail::algorithm_result_t<ExPolicy, FwdIter> hpx::search(ExPolicy &&policy, FwdIter first, FwdIter last, Searcher &&searcher)

Searches the range [first, last) using a searcher object. Executed according to the policy.

Template Parameters:

• ExPolicy – The type of the execution policy to use (deduced).

• FwdIter – The type of the source iterators (deduced).

• Searcher – A callable searcher object meeting the C++ Searcher requirements.

Parameters:

• policy – The execution policy to use.

• first – Refers to the beginning of the sequence to search.

• last – Refers to the end of the sequence to search.

• searcher – A callable object performing the search.

Returns:

The algorithm returns a hpx::future<FwdIter> if the execution policy is a task policy, or FwdIter otherwise.