Get rid of LegacyDefaultCallback

examples/simple_intersection/example_intersection.cpp

@@ -50,13 +50,12 @@ int main(int argc, char *argv[])
 
   ExecutionSpace space;
 
-  using Value = ArborX::PairValueIndex<Box>;
-
   ArborX::BoundingVolumeHierarchy const tree(
       space, ArborX::Experimental::attach_indices(boxes));
 
   // The query will resize values and offsets accordingly
-  Kokkos::View<Value *, MemorySpace> values("Example::values", 0);
+  Kokkos::View<typename decltype(tree)::value_type *, MemorySpace> values(
+      "Example::values", 0);
   Kokkos::View<int *, MemorySpace> offsets("Example::offsets", 0);
   tree.query(space, queries, values, offsets);
 
@@ -73,9 +72,9 @@ int main(int argc, char *argv[])
   std::copy(offsets_host.data(), offsets_host.data() + offsets.size(),
             std::ostream_iterator<int>(std::cout, " "));
   std::cout << "\nindices:";
-  for (int i = 0; i < values_host.extent_int(0); ++i)
-    std::cout << " " << values_host(i).index;
-  std::cout << '\n';
+  std::transform(values_host.data(), values_host.data() + values.size(),
+                 std::ostream_iterator<int>(std::cout, " "),
+                 [](auto value) { return value.index; });
 
   return 0;
 }

examples/triangle_intersection/triangle_intersection.cpp

@@ -88,15 +88,15 @@ int main(int argc, char *argv[])
       space, ArborX::Experimental::attach_indices(triangles));
 
   // The query will resize indices and offsets accordingly
-  Kokkos::View<unsigned *, MemorySpace> indices("Example::indices", 0);
+  Kokkos::View<typename decltype(tree)::value_type *, MemorySpace> values(
+      "Example::values", 0);
   Kokkos::View<int *, MemorySpace> offsets("Example::offsets", 0);
-  tree.query(space, queries, ArborX::Details::LegacyDefaultCallback{}, indices,
-             offsets);
+  tree.query(space, queries, values, offsets);
 
   auto offsets_host =
       Kokkos::create_mirror_view_and_copy(Kokkos::HostSpace{}, offsets);
-  auto indices_host =
-      Kokkos::create_mirror_view_and_copy(Kokkos::HostSpace{}, indices);
+  auto values_host =
+      Kokkos::create_mirror_view_and_copy(Kokkos::HostSpace{}, values);
 
   // Expected output:
   //   offsets: 0 1 2 3 4
@@ -105,8 +105,9 @@ int main(int argc, char *argv[])
   std::copy(offsets_host.data(), offsets_host.data() + offsets.size(),
             std::ostream_iterator<int>(std::cout, " "));
   std::cout << "\nindices: ";
-  std::copy(indices_host.data(), indices_host.data() + indices.size(),
-            std::ostream_iterator<int>(std::cout, " "));
+  std::transform(values_host.data(), values_host.data() + values.size(),
+                 std::ostream_iterator<int>(std::cout, " "),
+                 [](auto value) { return value.index; });
   std::cout << "\n";
 
   return 0;

src/spatial/detail/ArborX_Callbacks.hpp

@@ -45,21 +45,6 @@ struct DefaultCallback
   }
 };
 
-struct LegacyDefaultCallback
-{
-  template <typename Query, typename Value, typename Index,
-            typename OutputFunctor>
-  KOKKOS_FUNCTION void operator()(Query const &,
-                                  PairValueIndex<Value, Index> const &value,
-                                  OutputFunctor const &output) const
-  {
-    // APIv1 callback has the signature operator()(Query, int)
-    // As we store PairValueIndex with potentially non int index (like
-    // unsigned), we explicitly cast it here.
-    output((int)value.index);
-  }
-};
-
 // archetypal alias for a 'tag' type member in user callbacks
 template <typename Callback>
 using CallbackTagArchetypeAlias = typename Callback::tag;

test/ArborXTest_LegacyTree.hpp

@@ -134,7 +134,9 @@ class LegacyTree : public Tree
   query(ExecutionSpace const &space, Predicates const &predicates, View &&view,
         Args &&...args) const
   {
-    Tree::query(space, predicates, ArborX::Details::LegacyDefaultCallback{},
+    Tree::query(space, predicates,
+                LegacyCallbackWrapper<ArborX::Details::DefaultCallback>{
+                    ArborX::Details::DefaultCallback{}},
                 std::forward<View>(view), std::forward<Args>(args)...);
   }
 
@@ -159,7 +161,9 @@ class LegacyTree : public Tree
     {
       Kokkos::View<int *, typename Tree::memory_space> indices(
           "Testing::indices", 0);
-      Tree::query(space, predicates, ArborX::Details::LegacyDefaultCallback{},
+      Tree::query(space, predicates,
+                  LegacyCallbackWrapper<ArborX::Details::DefaultCallback>{
+                      ArborX::Details::DefaultCallback{}},
                   indices, std::forward<OffsetView>(offset),
                   std::forward<Args>(args)...);
       callback(predicates, std::forward<OffsetView>(offset), indices,