From f2496c9d051b8da2e9dedf633766484f840541ba Mon Sep 17 00:00:00 2001
From: Zak-K-Abdi <zakaria.a@outlook.com>
Date: Wed, 29 May 2024 18:39:55 +0100
Subject: [PATCH] Contains and contains_subrange parallel algorithm
 implementaion

---
 libs/core/algorithms/CMakeLists.txt           |   1 +
 .../include/hpx/parallel/algorithm.hpp        |   1 +
 .../hpx/parallel/algorithms/contains.hpp      | 136 ++++++++++++++++++
 .../parallel/algorithms/detail/contains.hpp   |  57 ++++++++
 4 files changed, 195 insertions(+)
 create mode 100644 libs/core/algorithms/include/hpx/parallel/algorithms/contains.hpp
 create mode 100644 libs/core/algorithms/include/hpx/parallel/algorithms/detail/contains.hpp

diff --git a/libs/core/algorithms/CMakeLists.txt b/libs/core/algorithms/CMakeLists.txt
index 6d10912d4d63..d48825b5a688 100644
--- a/libs/core/algorithms/CMakeLists.txt
+++ b/libs/core/algorithms/CMakeLists.txt
@@ -15,6 +15,7 @@ set(algorithms_headers
     hpx/parallel/algorithms/adjacent_difference.hpp
     hpx/parallel/algorithms/adjacent_find.hpp
     hpx/parallel/algorithms/all_any_none.hpp
+    hpx/parallel/algorithms/contains.hpp
     hpx/parallel/algorithms/copy.hpp
     hpx/parallel/algorithms/count.hpp
     hpx/parallel/algorithms/destroy.hpp
diff --git a/libs/core/algorithms/include/hpx/parallel/algorithm.hpp b/libs/core/algorithms/include/hpx/parallel/algorithm.hpp
index 4aedd3d820c7..309cdf842b25 100644
--- a/libs/core/algorithms/include/hpx/parallel/algorithm.hpp
+++ b/libs/core/algorithms/include/hpx/parallel/algorithm.hpp
@@ -16,6 +16,7 @@
 // Parallelism TS V1
 #include <hpx/parallel/algorithms/adjacent_find.hpp>
 #include <hpx/parallel/algorithms/all_any_none.hpp>
+#include <hpx/parallel/algorithms/contains.hpp>
 #include <hpx/parallel/algorithms/copy.hpp>
 #include <hpx/parallel/algorithms/count.hpp>
 #include <hpx/parallel/algorithms/equal.hpp>
diff --git a/libs/core/algorithms/include/hpx/parallel/algorithms/contains.hpp b/libs/core/algorithms/include/hpx/parallel/algorithms/contains.hpp
new file mode 100644
index 000000000000..fe6d6ba5e5d3
--- /dev/null
+++ b/libs/core/algorithms/include/hpx/parallel/algorithms/contains.hpp
@@ -0,0 +1,136 @@
+#pragma once
+
+#include <hpx/config.hpp>
+#include <hpx/execution/algorithms/detail/predicates.hpp>
+#include <hpx/executors/execution_policy.hpp>
+#include <hpx/iterator_support/traits/is_iterator.hpp>
+#include <hpx/parallel/algorithms/detail/dispatch.hpp>
+#include <hpx/parallel/algorithms/detail/distance.hpp>
+#include <hpx/parallel/util/detail/algorithm_result.hpp>
+#include <hpx/parallel/util/loop.hpp>
+#include <hpx/type_support/identity.hpp>
+#include <hpx/parallel/util/cancellation_token.hpp>
+#include <hpx/parallel/util/partitioner.hpp>
+#include <hpx/parallel/util/zip_iterator.hpp>
+#include <hpx/coroutines/thread_enums.hpp>
+#include <hpx/parallel/util/adapt_placement_mode.hpp>
+#include <hpx/parallel/algorithms/detail/contains.hpp>
+
+#include <algorithm>
+#include <cstddef>
+#include <iterator>
+#include <type_traits>
+#include <utility>
+
+namespace hpx::parallel {
+    namespace detail {
+        struct contains : public algorithm<contains, bool>
+        {
+            constexpr contains() noexcept
+              : algorithm("contains")
+            {
+
+            }
+
+            template <typename ExPolicy, typename Iterator, typename Sentinel,
+                typename T, typename Proj>
+            static constexpr bool sequential(ExPolicy, Iterator first,
+                Sentinel last, const T& val, Proj&& proj)
+            {
+                return sequential_contains<std::decay<ExPolicy>>(first, last,
+                    val, HPX_FORWARD(Proj, proj));
+            }
+
+            template <typename ExPolicy, typename Iterator, typename Sentinel,
+                typename T, typename Proj>
+            static util::detail::algorithm_result_t<ExPolicy, bool> parallel(
+                ExPolicy&& orgpolicy, Iterator first, Sentinel last, const T& val,
+                Proj&& proj)
+            {
+                const std::size_t count = detail::distance(first, last);
+                if (count <= 0)
+                    return util::detail::algorithm_result<ExPolicy, bool>::get(
+                        false);
+
+                decltype(auto) policy = parallel::util::adapt_placement_mode(
+                    HPX_FORWARD(ExPolicy, orgpolicy),
+                    hpx::threads::thread_placement_hint::breadth_first);
+
+                using policy_type = std::decay_t<decltype(policy)>;
+                util::cancellation_token<> tok;
+                auto f1 = [val, tok, proj]
+                    (Iterator first, std::size_t count)
+                {
+                    sequential_contains<policy_type>(first, val, count, tok, proj);
+                    return tok.was_cancelled();
+                };
+
+                auto f2 = [](auto&& results)
+                {
+                    return std::any_of(hpx::util::begin(results),
+                        hpx::util::end(results),
+                        [](hpx::future<bool>& val) { return val.get();});
+                };
+                
+                return util::partitioner<policy_type, bool>::call(
+                    HPX_FORWARD(decltype(policy), policy), first, count,
+                    HPX_MOVE(f1), HPX_MOVE(f2)
+                    );
+            }
+        };
+    }
+}
+namespace hpx {
+
+    inline constexpr struct contains_t final
+      : hpx::functional::detail::tag_fallback<contains_t>
+    {
+    private:
+        template <typename Iterator, typename Sentinel,
+            typename T, typename Proj = hpx::identity,
+            HPX_CONCEPT_REQUIRES_(
+                hpx::traits::is_iterator_v<Iterator> &&
+                hpx::traits::is_iterator_v<Iterator> &&
+                hpx::is_invocable_v<Proj,
+                typename std::iterator_traits<Iterator>::value_type>
+            )>
+
+        friend bool tag_fallback_invoke(hpx::contains_t, Iterator first,
+            Sentinel last, const T& val, Proj&& proj = Proj())
+        {
+            static_assert(hpx::traits::is_input_iterator_v<Iterator>,
+                "Required at least input iterator.");
+
+            static_assert(hpx::traits::is_input_iterator_v<Sentinel>,
+                "Required at least input iterator.");
+
+            return hpx::parallel::detail::contains().call(hpx::execution::seq,
+                first, last, val, proj);
+        }
+
+        template <typename ExPolicy, typename Iterator, typename Sentinel,
+            typename T, typename Proj = hpx::identity, HPX_CONCEPT_REQUIRES_(
+            hpx::is_execution_policy_v<ExPolicy> &&
+            hpx::traits::is_iterator_v<Iterator> &&
+            hpx::traits::is_iterator_v<Iterator> &&
+            hpx::is_invocable_v<Proj,
+            typename std::iterator_traits<Iterator>::value_type>)>
+
+        friend typename parallel::util::detail::algorithm_result<ExPolicy,
+            bool>::type
+        tag_fallback_invoke(hpx::contains_t, ExPolicy&& policy, Iterator first,
+            Sentinel last, T const& val, Proj&& proj = Proj())
+        {
+            static_assert(hpx::traits::is_iterator_v<Iterator>,
+                "Required at least iterator.");
+
+            static_assert(hpx::traits::is_iterator_v<Sentinel>,
+                "Required at least iterator.");
+
+            return hpx::parallel::detail::contains().call(
+                HPX_FORWARD(ExPolicy, policy), first, last, val,
+                HPX_FORWARD(Proj, proj));
+        }
+
+    } contains{};
+}
\ No newline at end of file
diff --git a/libs/core/algorithms/include/hpx/parallel/algorithms/detail/contains.hpp b/libs/core/algorithms/include/hpx/parallel/algorithms/detail/contains.hpp
new file mode 100644
index 000000000000..411d302c5332
--- /dev/null
+++ b/libs/core/algorithms/include/hpx/parallel/algorithms/detail/contains.hpp
@@ -0,0 +1,57 @@
+#pragma once
+
+#include <hpx/config.hpp>
+#include <hpx/functional/detail/tag_fallback_invoke.hpp>
+#include <hpx/functional/invoke.hpp>
+#include <hpx/parallel/util/loop.hpp>
+
+#include <algorithm>
+#include <cstddef>
+#include <type_traits>
+#include <utility>
+
+
+namespace hpx::parallel::detail {
+
+    template <typename ExPolicy>
+    struct sequential_contains_t final
+        : hpx::functional::detail::tag_fallback<sequential_contains_t<ExPolicy>>
+    {
+    private:
+        template <typename Iterator, typename Sentinel, typename T, typename Proj>
+        friend constexpr bool tag_fallback_invoke(sequential_contains_t,
+            Iterator first, Sentinel last, const T& val, Proj&& proj)
+        {
+            const std::size_t distance = detail::distance(first, last);
+            if (distance <= 0)
+                return false;
+
+            const auto itr = util::loop_pred<
+                std::decay_t<hpx::execution::sequenced_policy>>(first, last,
+                [&val, &proj] (const auto& cur)
+                { return HPX_INVOKE(proj, *cur) == val; });
+
+            return itr != last;
+        }
+
+        template <typename Iterator, typename T, typename Token, typename Proj>
+        friend constexpr void tag_fallback_invoke(sequential_contains_t,
+            Iterator first, T const& val, std::size_t count, Token& tok, Proj&& proj)
+        {
+            util::loop_n<ExPolicy>(first, count, tok,
+                [&val, &tok, &proj] (const auto& cur)
+                {
+                    if (HPX_INVOKE(proj, *cur) == val)
+                    {
+                        tok.cancel();
+                        return;
+                    }
+                });
+        }
+
+
+    };
+    template <typename ExPolicy>
+    inline constexpr sequential_contains_t<ExPolicy> sequential_contains =
+        sequential_contains_t<ExPolicy>{};
+} //namespace hpx::parallel::detail
\ No newline at end of file