Implement sort_by_key (kokkos#6801)

* Implement sort_by_key

* Address review comments

* Make passed in view const ref

* Fix _via_sort for OpenMPTarget

Co-authored-by: Daniel Arndt <arndtd@ornl.gov>

* Rip out ROCThrust for now

* Few changes to address the comments

* Fix SYCL

* Fix SYCL implementation

---------

Co-authored-by: Daniel Arndt <arndtd@ornl.gov>

algorithms/src/Kokkos_Sort.hpp

@@ -23,6 +23,7 @@
 
 #include "sorting/Kokkos_BinSortPublicAPI.hpp"
 #include "sorting/Kokkos_SortPublicAPI.hpp"
+#include "sorting/Kokkos_SortByKeyPublicAPI.hpp"
 #include "sorting/Kokkos_NestedSortPublicAPI.hpp"
 
 #ifdef KOKKOS_IMPL_PUBLIC_INCLUDE_NOTDEFINED_SORT

algorithms/src/sorting/Kokkos_SortByKeyPublicAPI.hpp

@@ -0,0 +1,117 @@
+//@HEADER
+// ************************************************************************
+//
+//                        Kokkos v. 4.0
+//       Copyright (2022) National Technology & Engineering
+//               Solutions of Sandia, LLC (NTESS).
+//
+// Under the terms of Contract DE-NA0003525 with NTESS,
+// the U.S. Government retains certain rights in this software.
+//
+// Part of Kokkos, under the Apache License v2.0 with LLVM Exceptions.
+// See https://kokkos.org/LICENSE for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//@HEADER
+
+#ifndef KOKKOS_SORT_BY_KEY_PUBLIC_API_HPP_
+#define KOKKOS_SORT_BY_KEY_PUBLIC_API_HPP_
+
+#include "./impl/Kokkos_SortByKeyImpl.hpp"
+#include <Kokkos_Core.hpp>
+#include <algorithm>
+
+namespace Kokkos::Experimental {
+
+// ---------------------------------------------------------------
+// basic overloads
+// ---------------------------------------------------------------
+
+template <class ExecutionSpace, class KeysDataType, class... KeysProperties,
+          class ValuesDataType, class... ValuesProperties>
+void sort_by_key(
+    const ExecutionSpace& exec,
+    const Kokkos::View<KeysDataType, KeysProperties...>& keys,
+    const Kokkos::View<ValuesDataType, ValuesProperties...>& values) {
+  // constraints
+  using KeysType   = Kokkos::View<KeysDataType, KeysProperties...>;
+  using ValuesType = Kokkos::View<ValuesDataType, ValuesProperties...>;
+  ::Kokkos::Impl::static_assert_is_admissible_to_kokkos_sort_by_key(keys);
+  ::Kokkos::Impl::static_assert_is_admissible_to_kokkos_sort_by_key(values);
+
+  static_assert(SpaceAccessibility<ExecutionSpace,
+                                   typename KeysType::memory_space>::accessible,
+                "Kokkos::sort: execution space instance is not able to access "
+                "the memory space of the keys View argument!");
+  static_assert(
+      SpaceAccessibility<ExecutionSpace,
+                         typename ValuesType::memory_space>::accessible,
+      "Kokkos::sort: execution space instance is not able to access "
+      "the memory space of the values View argument!");
+
+  static_assert(KeysType::static_extent(0) == 0 ||
+                ValuesType::static_extent(0) == 0 ||
+                KeysType::static_extent(0) == ValuesType::static_extent(0));
+  if (values.size() != keys.size())
+    Kokkos::abort((std::string("values and keys extents must be the same. The "
+                               "values extent is ") +
+                   std::to_string(values.size()) + ", and the keys extent is " +
+                   std::to_string(keys.size()) + ".")
+                      .c_str());
+
+  if (keys.extent(0) <= 1) {
+    return;
+  }
+
+  ::Kokkos::Impl::sort_by_key_device_view_without_comparator(exec, keys,
+                                                             values);
+}
+
+// ---------------------------------------------------------------
+// overloads supporting a custom comparator
+// ---------------------------------------------------------------
+
+template <class ExecutionSpace, class ComparatorType, class KeysDataType,
+          class... KeysProperties, class ValuesDataType,
+          class... ValuesProperties>
+void sort_by_key(
+    const ExecutionSpace& exec,
+    const Kokkos::View<KeysDataType, KeysProperties...>& keys,
+    const Kokkos::View<ValuesDataType, ValuesProperties...>& values,
+    const ComparatorType& comparator) {
+  // constraints
+  using KeysType   = Kokkos::View<KeysDataType, KeysProperties...>;
+  using ValuesType = Kokkos::View<ValuesDataType, ValuesProperties...>;
+  ::Kokkos::Impl::static_assert_is_admissible_to_kokkos_sort_by_key(keys);
+  ::Kokkos::Impl::static_assert_is_admissible_to_kokkos_sort_by_key(values);
+
+  static_assert(SpaceAccessibility<ExecutionSpace,
+                                   typename KeysType::memory_space>::accessible,
+                "Kokkos::sort: execution space instance is not able to access "
+                "the memory space of the keys View argument!");
+  static_assert(
+      SpaceAccessibility<ExecutionSpace,
+                         typename ValuesType::memory_space>::accessible,
+      "Kokkos::sort: execution space instance is not able to access "
+      "the memory space of the values View argument!");
+
+  static_assert(KeysType::static_extent(0) == 0 ||
+                ValuesType::static_extent(0) == 0 ||
+                KeysType::static_extent(0) == ValuesType::static_extent(0));
+  if (values.size() != keys.size())
+    Kokkos::abort((std::string("values and keys extents must be the same. The "
+                               "values extent is ") +
+                   std::to_string(values.size()) + ", and the keys extent is " +
+                   std::to_string(keys.size()) + ".")
+                      .c_str());
+
+  if (keys.extent(0) <= 1) {
+    return;
+  }
+
+  ::Kokkos::Impl::sort_by_key_device_view_with_comparator(exec, keys, values,
+                                                          comparator);
+}
+
+}  // namespace Kokkos::Experimental
+#endif