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namespace tf {
/** @page ParallelSort Parallel Sort
%Taskflow provides template functions for constructing tasks
to sort ranges of items in parallel.
@tableofcontents
@section ParallelSortInclude Include the Header
You need to include the header file, <tt>taskflow/algorithm/sort.hpp</tt>,
for creating a parallel-sort task.
@code{.cpp}
#include <taskflow/algorithm/sort.hpp>
@endcode
@section SortARangeOfItems Sort a Range of Items
The task created by tf::Taskflow::sort(B first, E last)
performs parallel sort to rank a range of elements specified by
<tt>[first, last)</tt> in increasing order.
The given iterators must be @em random-accessible.
The following example creates a task to sort a data vector in increasing order.
@code{.cpp}
tf::Taskflow taskflow;
tf::Executor executor;
std::vector<int> data = {1, 4, 9, 2, 3, 11, -8};
tf::Task sort = taskflow.sort(data.begin(), data.end());
executor.run(taskflow).wait();
assert(std::is_sorted(data.begin(), data.end()));
@endcode
@attention
Elements are compared using the operator @c <.
@section SortARangeOfItemsWithACustomComparator Sort a Range of Items with a Custom Comparator
tf::Taskflow::sort(B first, E last, C cmp) is an overload of
parallel sort that allows users to specify a custom comparator.
The following example sorts a data vector in decreasing order.
@code{.cpp}
tf::Taskflow taskflow;
tf::Executor executor;
std::vector<int> data = {1, 4, 9, 2, 3, 11, -8};
tf::Task sort = taskflow.sort(data.begin(), data.end(),
[](int a, int b) { return a > b; }
);
executor.run(taskflow).wait();
assert(std::is_sorted(data.begin(), data.end(), std::greater<int>{}));
@endcode
@attention
tf::Taskflow::sort is not stable. That is, two or more objects with equal keys
may not appear in the same order before sorting.
@section ParallelSortEnableStatefulDataPassing Enable Stateful Data Passing
The iterators taken by tf::Taskflow::sort are templated.
You can use std::reference_wrapper to enable stateful data passing
between the sort task and others.
The following example creates a task @c init to initialize the data vector
and a task @c sort to sort the data in parallel after @c init finishes.
@code{.cpp}
tf::Taskflow taskflow;
tf::Executor executor;
std::vector<int> data;
std::vector<int>::iterator first, last;
tf::Task init = taskflow.emplace([&](){
data = {1, 4, 9, 2, 3, 11, -8};
first = data.begin();
last = data.end();
});
tf::Task sort = taskflow.sort(
std::ref(first), std::ref(last), [] (int l, int r) { return l < r; }
);
init.precede(sort);
executor.run(taskflow).wait();
assert(std::is_sorted(data.begin(), data.end()));
@endcode
*/
}
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