[...block] updated grid layer usage

dune/gdt/playground/mapper/block.hh

@@ -105,7 +105,7 @@ private:
   private:
     static size_t find_block_of_(const MsGridType& ms_grid, const Comdim0EntityType& entity)
     {
-      const auto global_entity_index = ms_grid.globalGridView()->indexSet().index(entity);
+      const auto global_entity_index = ms_grid.globalGridView().indexSet().index(entity);
       const auto result              = ms_grid.entityToSubdomainMap()->find(global_entity_index);
 #ifndef NDEBUG
       if (result == ms_grid.entityToSubdomainMap()->end())

dune/gdt/playground/spaces/block.hh

@@ -58,6 +58,10 @@ public:
 } // namespace internal
 
 
+/**
+ * \todo This can be implemented easier by now. Since all local spaces hold a copy of their local grid view it should
+ *       be enough to hold a copy of the global grid view in this space (if the ms_grid is not needed elsewhere)
+ */
 template <class LocalSpaceImp>
 class Block : public SpaceInterface<internal::BlockTraits<LocalSpaceImp>>
 {
@@ -81,6 +85,7 @@ public:
   Block(const std::shared_ptr<const MsGridType>& ms_grid,
         const std::vector<std::shared_ptr<const LocalSpaceType>>& local_spaces)
     : ms_grid_(ms_grid)
+    , grid_view_(ms_grid_->globalGridView())
     , local_spaces_(local_spaces)
     , mapper_(std::make_shared<MapperType>(ms_grid_, local_spaces_))
   {
@@ -114,7 +119,7 @@ public:
 
   const GridViewType& grid_view() const
   {
-    return ms_grid_->globalGridView();
+    return grid_view_;
   }
 
   const BackendType& backend() const
@@ -156,7 +161,7 @@ private:
   template <class EntityType>
   size_t find_block_of_(const EntityType& entity) const
   {
-    const auto global_entity_index = ms_grid_->globalGridView()->indexSet().index(entity);
+    const auto global_entity_index = ms_grid_->globalGridView().indexSet().index(entity);
     const auto result              = ms_grid_->entityToSubdomainMap()->find(global_entity_index);
 #ifndef NDEBUG
     if (result == ms_grid_->entityToSubdomainMap()->end())
@@ -179,6 +184,7 @@ private:
   } // ... find_block_of_(...)
 
   const std::shared_ptr<const MsGridType> ms_grid_;
+  const GridViewType grid_view_;
   const std::vector<std::shared_ptr<const LocalSpaceType>> local_spaces_;
   const std::shared_ptr<const MapperType> mapper_;
 }; // class Block