Add unit test cases and fixes for the S/R versions of the parallel algorithms

.circleci/tests.unit1.algorithms

@@ -5,7 +5,6 @@
 #  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 
 tests.unit.modules.algorithms.algorithms.adjacentdifference
-tests.unit.modules.algorithms.algorithms.adjacentdifference_sender
 tests.unit.modules.algorithms.algorithms.adjacentfind
 tests.unit.modules.algorithms.algorithms.adjacentfind_binary
 tests.unit.modules.algorithms.algorithms.all_of
@@ -31,7 +30,6 @@ tests.unit.modules.algorithms.algorithms.exclusive_scan_validate
 tests.unit.modules.algorithms.algorithms.fill
 tests.unit.modules.algorithms.algorithms.filln
 tests.unit.modules.algorithms.algorithms.find
-tests.unit.modules.algorithms.algorithms.find_sender
 tests.unit.modules.algorithms.algorithms.findend
 tests.unit.modules.algorithms.algorithms.findfirstof
 tests.unit.modules.algorithms.algorithms.findfirstof_binary
@@ -40,7 +38,6 @@ tests.unit.modules.algorithms.algorithms.findifnot
 tests.unit.modules.algorithms.algorithms.foreach
 tests.unit.modules.algorithms.algorithms.foreach_executors
 tests.unit.modules.algorithms.algorithms.foreach_prefetching
-tests.unit.modules.algorithms.algorithms.foreach_sender
 tests.unit.modules.algorithms.algorithms.foreach_scheduler
 tests.unit.modules.algorithms.algorithms.foreachn
 tests.unit.modules.algorithms.algorithms.foreachn_exception
@@ -53,7 +50,6 @@ tests.unit.modules.algorithms.algorithms.for_loop_n
 tests.unit.modules.algorithms.algorithms.for_loop_n_strided
 tests.unit.modules.algorithms.algorithms.for_loop_reduction
 tests.unit.modules.algorithms.algorithms.for_loop_reduction_async
-tests.unit.modules.algorithms.algorithms.for_loop_sender
 tests.unit.modules.algorithms.algorithms.for_loop_strided
 tests.unit.modules.algorithms.algorithms.generate
 tests.unit.modules.algorithms.algorithms.generaten
@@ -74,3 +70,5 @@ tests.unit.modules.algorithms.algorithms.min_element
 tests.unit.modules.algorithms.algorithms.minmax_element
 tests.unit.modules.algorithms.algorithms.mismatch
 tests.unit.modules.algorithms.algorithms.mismatch_binary
+tests.unit.modules.algorithms.algorithms.move
+tests.unit.modules.algorithms.algorithms.nth_element

.circleci/tests.unit2.algorithms

@@ -4,8 +4,6 @@
 #  Distributed under the Boost Software License, Version 1.0. (See accompanying
 #  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 
-tests.unit.modules.algorithms.algorithms.move
-tests.unit.modules.algorithms.algorithms.nth_element
 tests.unit.modules.algorithms.algorithms.none_of
 tests.unit.modules.algorithms.algorithms.parallel_sort
 tests.unit.modules.algorithms.algorithms.partial_sort
@@ -15,7 +13,6 @@ tests.unit.modules.algorithms.algorithms.partition_copy
 tests.unit.modules.algorithms.algorithms.reduce_
 tests.unit.modules.algorithms.algorithms.reduce_by_key
 tests.unit.modules.algorithms.algorithms.remove
-tests.unit.modules.algorithms.algorithms.remove 
 tests.unit.modules.algorithms.algorithms.remove1
 tests.unit.modules.algorithms.algorithms.remove2
 tests.unit.modules.algorithms.algorithms.remove_if
@@ -28,10 +25,8 @@ tests.unit.modules.algorithms.algorithms.replace_copy
 tests.unit.modules.algorithms.algorithms.replace_copy_if
 tests.unit.modules.algorithms.algorithms.reverse
 tests.unit.modules.algorithms.algorithms.reverse_copy
-tests.unit.modules.algorithms.algorithms.reverse_sender
 tests.unit.modules.algorithms.algorithms.rotate
 tests.unit.modules.algorithms.algorithms.rotate_copy
-tests.unit.modules.algorithms.algorithms.rotate_sender
 tests.unit.modules.algorithms.algorithms.search
 tests.unit.modules.algorithms.algorithms.searchn
 tests.unit.modules.algorithms.algorithms.set_difference

libs/core/algorithms/include/hpx/parallel/algorithms/adjacent_difference.hpp

@@ -276,27 +276,34 @@ namespace hpx::parallel {
                     util::detail::algorithm_result<ExPolicy, FwdIter2>;
                 using difference_type =
                     typename std::iterator_traits<FwdIter1>::difference_type;
-
-                constexpr bool scheduler_policy =
+                constexpr bool has_scheduler_policy =
                     hpx::execution_policy_has_scheduler_executor_v<ExPolicy>;
 
-                if constexpr (!scheduler_policy)
+                FwdIter1 prev = first;
+                difference_type count;
+
+                if (first == last)
                 {
-                    if (first == last)
+                    if constexpr (!has_scheduler_policy)
                     {
                         return result::get(HPX_MOVE(dest));
                     }
+                    else
+                    {
+                        count = static_cast<difference_type>(0);
+                    }
                 }
+                else
+                {
+                    count = detail::distance(first, last) - 1;
 
-                difference_type count = detail::distance(first, last) - 1;
-
-                FwdIter1 prev = first;
-                hpx::traits::proxy_value_t<
-                    typename std::iterator_traits<FwdIter1>::value_type>
-                    tmp = *first++;
-                *dest++ = HPX_MOVE(tmp);
+                    hpx::traits::proxy_value_t<
+                        typename std::iterator_traits<FwdIter1>::value_type>
+                        tmp = *first++;
+                    *dest++ = HPX_MOVE(tmp);
+                }
 
-                if constexpr (!scheduler_policy)
+                if constexpr (!has_scheduler_policy)
                 {
                     if (count == 0)
                     {

libs/core/algorithms/include/hpx/parallel/algorithms/adjacent_find.hpp

@@ -173,18 +173,24 @@ namespace hpx::parallel {
 
             template <typename ExPolicy, typename FwdIter, typename Sent_,
                 typename Pred, typename Proj>
-            static util::detail::algorithm_result_t<ExPolicy, FwdIter> parallel(
-                ExPolicy&& orgpolicy, FwdIter first, Sent_ last, Pred&& pred,
-                Proj&& proj)
+            static decltype(auto) parallel(ExPolicy&& orgpolicy, FwdIter first,
+                Sent_ last, Pred&& pred, Proj&& proj)
             {
                 using zip_iterator = hpx::util::zip_iterator<FwdIter, FwdIter>;
                 using difference_type =
                     typename std::iterator_traits<FwdIter>::difference_type;
+                using result =
+                    util::detail::algorithm_result<ExPolicy, FwdIter>;
 
-                if (first == last)
+                constexpr bool has_scheduler_executor =
+                    hpx::execution_policy_has_scheduler_executor_v<ExPolicy>;
+
+                if constexpr (!has_scheduler_executor)
                 {
-                    return util::detail::algorithm_result<ExPolicy,
-                        FwdIter>::get(HPX_MOVE(last));
+                    if (first == last)
+                    {
+                        return result::get(HPX_MOVE(last));
+                    }
                 }
 
                 decltype(auto) policy = parallel::util::adapt_placement_mode(
@@ -209,10 +215,15 @@ namespace hpx::parallel {
                 };
 
                 auto f2 = [tok, count, first, last](
-                              auto&& data) mutable -> FwdIter {
-                    // make sure iterators embedded in function object that is
-                    // attached to futures are invalidated
-                    util::detail::clear_container(data);
+                              auto&&... data) mutable -> FwdIter {
+                    static_assert(sizeof...(data) < 2);
+                    if constexpr (sizeof...(data) == 1)
+                    {
+                        // make sure iterators embedded in function object that
+                        // is attached to futures are invalidated
+                        util::detail::clear_container(data...);
+                    }
+
                     difference_type adj_find_res = tok.get_data();
                     if (adj_find_res != count)
                     {
@@ -222,9 +233,16 @@ namespace hpx::parallel {
                     {
                         first = last;
                     }
-                    return HPX_MOVE(first);
+                    return first;
                 };
 
+                if constexpr (has_scheduler_executor)
+                {
+                    // underflow prevention for the upcoming call
+                    if (count == 0)
+                        ++count;
+                }
+
                 using partitioner_type =
                     util::partitioner<policy_type, FwdIter, void>;
                 return partitioner_type::call_with_index(
@@ -269,10 +287,8 @@ namespace hpx {
                 hpx::traits::is_forward_iterator_v<FwdIter>
             )>
         // clang-format on
-        friend typename parallel::util::detail::algorithm_result<ExPolicy,
-            FwdIter>::type
-        tag_fallback_invoke(hpx::adjacent_find_t, ExPolicy&& policy,
-            FwdIter first, FwdIter last, Pred pred = Pred())
+        friend decltype(auto) tag_fallback_invoke(hpx::adjacent_find_t,
+            ExPolicy&& policy, FwdIter first, FwdIter last, Pred pred = Pred())
         {
             static_assert(hpx::traits::is_forward_iterator_v<FwdIter>,
                 "Requires at least a forward iterator");