Neo: handle empty connectivity in the graph.

arctools/neo/src/neo/Items.h

@@ -1,11 +1,11 @@
 // -*- tab-width: 2; indent-tabs-mode: nil; coding: utf-8-with-signature -*-
 //-----------------------------------------------------------------------------
-// Copyright 2000-2024 CEA (www.cea.fr) IFPEN (www.ifpenergiesnouvelles.com)
+// Copyright 2000-2025 CEA (www.cea.fr) IFPEN (www.ifpenergiesnouvelles.com)
 // See the top-level COPYRIGHT file for details.
 // SPDX-License-Identifier: Apache-2.0
 //-----------------------------------------------------------------------------
 /*---------------------------------------------------------------------------*/
-/* Items                                     (C) 2000-2024                   */
+/* Items                                     (C) 2000-2025                   */
 /*                                                                           */
 /* Tooling to manipulate Mesh Items                                          */
 /*---------------------------------------------------------------------------*/
@@ -249,6 +249,13 @@ struct FutureItemRange
     return std::move(new_items);
   }
 
+  ItemRange::size_type size() const {
+    if (is_data_released)
+      throw std::runtime_error(
+      "Impossible to call FutureItemRange.size(), data already released.");
+    return new_items.size();
+  }
+
  private:
   virtual ItemRange& _toItemRange() {
     return new_items;

arctools/neo/src/neo/Mesh.h

@@ -82,6 +82,14 @@ class Mesh
       if (nb_connected_elements.size() == 0) {return 0;}
       return *std::max_element(nb_connected_elements.begin(), nb_connected_elements.end());
     }
+
+    bool isEmpty() const {
+      return maxNbConnectedItems() == 0;
+    }
+
+    friend bool operator==(Connectivity const& lhs, Connectivity const& rhs) {
+      return (lhs.source_family == rhs.source_family) && (lhs.target_family == rhs.target_family) && lhs.name == rhs.name;
+    }
   };
 
   enum class ConnectivityOperation

arctools/neo/src/neo/MeshSchedule.cpp

@@ -34,12 +34,17 @@ void Neo::Mesh::_scheduleAddConnectivity(Neo::Family& source_family, Neo::ItemRa
   // Create connectivity wrapper and add it to mesh
   auto& connectivity_property = source_family.getConcreteProperty<Mesh::ConnectivityPropertyType>(connectivity_unique_name);
   auto& connectivity_orientation = source_family.getConcreteProperty<Mesh::ConnectivityPropertyType>(orientation_name);
-  Connectivity current_connectivity = Connectivity {source_family,target_family,
-                                                    connectivity_unique_name,connectivity_property,
-                                                    connectivity_orientation};
-  auto [iterator, is_inserted] = m_connectivities.insert(std::make_pair(connectivity_unique_name,current_connectivity));
-  m_connectivities_per_family[{source_family.itemKind(),source_family.name()}].push_back(current_connectivity);
-  if (!is_inserted && add_or_modify == ConnectivityOperation::Add) {
+  Connectivity current_connectivity = Connectivity{ source_family, target_family,
+                                                    connectivity_unique_name, connectivity_property,
+                                                    connectivity_orientation };
+  auto [inserted_connectivity_iterator, is_inserted] = m_connectivities.insert(std::make_pair(connectivity_unique_name, current_connectivity));
+  auto& source_family_con = m_connectivities_per_family[{ source_family.itemKind(), source_family.name() }];
+  if (std::find(source_family_con.begin(),
+                source_family_con.end(),
+                current_connectivity) == source_family_con.end()) {
+    source_family_con.push_back(current_connectivity);
+  }
+  if (!is_inserted && add_or_modify == ConnectivityOperation::Add && !inserted_connectivity_iterator->second.isEmpty()) {
     throw std::invalid_argument("Cannot include already inserted connectivity " + connectivity_unique_name + ". Choose ConnectivityOperation::Modify");
   }
   m_mesh_graph->addAlgorithm(

arctools/neo/src/tests/NeoBaseTest.cpp

@@ -1,11 +1,11 @@
 // -*- tab-width: 2; indent-tabs-mode: nil; coding: utf-8-with-signature -*-
 //-----------------------------------------------------------------------------
-// Copyright 2000-2023 CEA (www.cea.fr) IFPEN (www.ifpenergiesnouvelles.com)
+// Copyright 2000-2025 CEA (www.cea.fr) IFPEN (www.ifpenergiesnouvelles.com)
 // See the top-level COPYRIGHT file for details.
 // SPDX-License-Identifier: Apache-2.0
 //-----------------------------------------------------------------------------
 /*---------------------------------------------------------------------------*/
-/* NeoBaseTest.cpp                                 (C) 2000-2023             */
+/* NeoBaseTest.cpp                                 (C) 2000-2025             */
 /*                                                                           */
 /* Base tests for Neo kernel                                                 */
 /*---------------------------------------------------------------------------*/
@@ -164,9 +164,11 @@ TEST(NeoTestItemRange, test_item_range) {
 
 TEST(NeoTestFutureItemRange, test_future_item_range) {
   Neo::FutureItemRange future_item_range{};
+  EXPECT_EQ(future_item_range.size(), 0);
   // Manually fill contained ItemRange
   std::vector<Neo::utils::Int32> lids{ 0, 2, 4, 6 };
   future_item_range.new_items = Neo::ItemRange{ Neo::ItemLocalIds{ lids } };
+  EXPECT_EQ(future_item_range.size(), lids.size());
   Neo::ItemRange& internal_range = future_item_range;
   EXPECT_EQ(&future_item_range.new_items, &internal_range);
   auto end_update = Neo::EndOfMeshUpdate{};
@@ -175,6 +177,7 @@ TEST(NeoTestFutureItemRange, test_future_item_range) {
     std::vector<int> filter{ 0, 1, 2 };
     auto filtered_future_range =
     Neo::make_future_range(future_item_range, filter);
+    EXPECT_EQ(filtered_future_range.size(), 0);
     // Get item_ranges
     auto filtered_range = filtered_future_range.get(end_update);
     auto item_range = future_item_range.get(end_update);

arctools/neo/src/tests/NeoMeshAPITest.cpp

@@ -238,6 +238,17 @@ TEST(NeoMeshApiTest, SetNodeCoordsTest) {
 
 /*---------------------------------------------------------------------------*/
 
+TEST(NeoMeshApiTest,EmptyMeshConnectivity) {
+  // Check empty connectivity
+  Neo::Family empty_family{Neo::ItemKind::IK_None, "EmptyFamily"};
+  Neo::Mesh::ConnectivityPropertyType empty_property{};
+  Neo::Mesh::Connectivity empty_connectivity{empty_family,empty_family,"empty_connectivity",
+    empty_property,empty_property};
+  EXPECT_TRUE(empty_connectivity.isEmpty());
+}
+
+/*---------------------------------------------------------------------------*/
+
 bool areEqual(Neo::Mesh::Connectivity const con1, Neo::Mesh::Connectivity const con2) {
   bool are_equal = con1.name == con2.name;
   are_equal &= &con1.source_family == &con2.source_family;
@@ -301,6 +312,10 @@ TEST(NeoMeshApiTest, AddItemConnectivity) {
   // check connectivities
   // check cell_to_nodes
   auto cell_to_nodes = mesh.getConnectivity(cell_family, node_family, cell_to_nodes_connectivity_name);
+  EXPECT_FALSE(cell_to_nodes.isEmpty());
+  // check operator ==
+  auto cell_to_nodes_copy{cell_to_nodes};
+  EXPECT_EQ(cell_to_nodes,cell_to_nodes_copy);
   EXPECT_EQ(cell_to_nodes_connectivity_name, cell_to_nodes.name);
   EXPECT_EQ(&cell_family, &cell_to_nodes.source_family);
   EXPECT_EQ(&node_family, &cell_to_nodes.target_family);
@@ -445,14 +460,23 @@ TEST(NeoMeshApiTest, AddAndChangeItemConnectivity) {
   auto future_dofs = Neo::FutureItemRange{};
   mesh.scheduleAddItems(cell_family, cell_uids, future_cells);
   mesh.scheduleAddItems(dof_family, dof_uids, future_dofs);
+  // Add en empty connectivity
+  mesh.scheduleAddConnectivity(cell_family, Neo::ItemRange{}, dof_family, 0,
+                               {}, "cell_to_dofs");
+  mesh.applyScheduledOperations();
+  // It is possible to modifiy an empty connectivity using ConnectivityOperation::Add (the default)
   mesh.scheduleAddConnectivity(cell_family, future_cells, dof_family, 3,
                                cell_dofs, "cell_to_dofs");
   mesh.applyScheduledOperations();
-
-  // Change an existing connectivity : cell 0 now points to dofs uids {3,4}
+  // Change an existing connectivity: cell 0 now points to dofs uids {3,4}
   auto cell_lids = cell_family.itemUniqueIdsToLocalids({ 0 });
   Neo::ItemRange cell_range{ cell_lids };
   auto connected_dofs = std::vector<Neo::utils::Int64>{ 3, 4 };
+  // First try using ConnectivityOperation::Add an existing connectivity: it fails
+  EXPECT_THROW(mesh.scheduleAddConnectivity(cell_family, cell_range, dof_family, 2,
+                               connected_dofs, "cell_to_dofs",
+                               Neo::Mesh::ConnectivityOperation::Add), std::invalid_argument);
+  // Second try using ConnectivityOperation::Add an existing connectivity: it works
   mesh.scheduleAddConnectivity(cell_family, cell_range, dof_family, 2,
                                connected_dofs, "cell_to_dofs",
                                Neo::Mesh::ConnectivityOperation::Modify);