From 1f8897cb46bfa6f151e21f5e6ccc3e4328988314 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      | 128 ++++++++++++++++++
 3 files changed, 130 insertions(+)
 create mode 100644 libs/core/algorithms/include/hpx/parallel/algorithms/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..d2b42c2cb59c
--- /dev/null
+++ b/libs/core/algorithms/include/hpx/parallel/algorithms/contains.hpp
@@ -0,0 +1,128 @@
+#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 <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)
+            {
+                auto const 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 ExPolicy, typename Iterator, typename Sentinel,
+                typename T, typename Proj>
+            static util::detail::algorithm_result_t<ExPolicy, bool> parallel(
+                ExPolicy&& policy, Iterator first, Sentinel last, const T& val,
+                Proj&& proj)
+            {
+                const auto distance = detail::distance(first, last);
+                if (distance <= 0)
+                {
+                    return util::detail::algorithm_result<ExPolicy, bool>::get(
+                        false);
+                }
+
+                const auto itr = util::loop_pred<
+                    std::decay_t<ExPolicy>>(first, last, [&val, &proj]
+                    (const auto& cur) { return HPX_INVOKE(proj, *cur) == val; });
+
+                if (itr == last)
+                {
+                    return util::detail::algorithm_result<ExPolicy, bool>::get(
+                        false);
+                }
+
+                return util::detail::algorithm_result<ExPolicy, bool>::get(true);
+            }
+
+        };
+    }
+}
+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