Pull out common routine mark_threshold

Author: schnellerhase

cpp/dolfinx/refinement/mark.h

@@ -20,6 +20,34 @@
 namespace dolfinx::refinement
 {
 
+namespace impl
+{
+
+/// @brief Threshold marking helper
+///
+/// @param[in] marker Input marker
+/// @param[in] threshold Lower bound for values to mark
+///
+/// @returns indices i which satisfy e_i > threshold.
+template <std::floating_point T>
+std::vector<std::int32_t> mark_threshold(std::span<const T> marker, T threshold)
+{
+  auto mark = [=](T e) { return e > threshold; };
+
+  std::vector<std::int32_t> indices;
+  indices.reserve(std::ranges::count_if(marker, mark));
+
+  for (std::int32_t i = 0; i < static_cast<std::int32_t>(marker.size()); ++i)
+  {
+    if (mark(marker[i]))
+      indices.push_back(i);
+  }
+
+  return indices;
+}
+
+} // namespace impl
+
 /// @brief Maximum marking of a marker.
 ///
 /// @param[in] marker Input marker (local) - usually an error indicator per
@@ -39,16 +67,7 @@ std::vector<std::int32_t> mark_maximum(std::span<const T> marker, T theta,
                          : std::ranges::max(marker);
   MPI_Allreduce(MPI_IN_PLACE, &max, 1, dolfinx::MPI::mpi_t<T>, MPI_MAX, comm);
 
-  auto mark = [=](T e) { return e > theta * max; };
-
-  std::vector<std::int32_t> indices;
-  indices.reserve(std::ranges::count_if(marker, mark));
-
-  for (std::int32_t i = 0; i < static_cast<std::int32_t>(marker.size()); ++i)
-  {
-    if (mark(marker[i]))
-      indices.push_back(i);
-  }
+  auto indices = impl::mark_threshold<T>(marker, theta * max);
 
   spdlog::info("Marking (max) {} / {} (local) entities.", indices.size(),
                marker.size());
@@ -83,16 +102,7 @@ std::vector<std::int32_t> mark_equidistribution(std::span<const T> marker,
   MPI_Allreduce(MPI_IN_PLACE, &count, 1, dolfinx::MPI::mpi_t<std::int32_t>,
                 MPI_SUM, comm);
 
-  auto mark = [=](T e) { return e > theta * norm / std::sqrt(count); };
-
-  std::vector<std::int32_t> indices;
-  indices.reserve(std::ranges::count_if(marker, mark));
-
-  for (std::int32_t i = 0; i < static_cast<std::int32_t>(marker.size()); ++i)
-  {
-    if (mark(marker[i]))
-      indices.push_back(i);
-  }
+  auto indices = impl::mark_threshold<T>(marker, theta * norm / std::sqrt(count));
 
   spdlog::info("Marking (equi) {} / {} (local) entities.", indices.size(),
                marker.size());