Add NodeByCellData::SubViewConst

src/scheme/NodeByCellData.hpp

@@ -58,6 +58,42 @@ class NodeByCellData
     }
   };
 
+  class SubViewConst
+  {
+   private:
+    KOKKOS_RESTRICT const DataType* const m_sub_values;
+    const size_t m_size;
+   public:
+    KOKKOS_INLINE_FUNCTION
+    const DataType& operator[](const size_t& i) const
+    {
+      Assert(i<m_size);
+      return m_sub_values[i];
+    }
+
+    KOKKOS_INLINE_FUNCTION
+    const size_t& size() const
+    {
+      return m_size;
+    }
+
+    SubViewConst(const SubViewConst&) = delete;
+
+    KOKKOS_INLINE_FUNCTION
+    SubViewConst(SubViewConst&&) = default;
+
+    KOKKOS_INLINE_FUNCTION
+    SubViewConst(const Kokkos::View<DataType*>& values,
+                 const size_t& begin,
+                 const size_t& end)
+        : m_sub_values(&(values[begin])),
+          m_size(end-begin)
+    {
+      Assert(begin<=end);
+      Assert(end<=values.extent(0));
+    }
+  };
+
   KOKKOS_INLINE_FUNCTION
   DataType& operator()(const size_t& j, const size_t& r)
   {
@@ -108,6 +144,14 @@ class NodeByCellData
     return SubView(m_values, cell_begin, cell_end);
   }
 
+  KOKKOS_INLINE_FUNCTION
+  SubViewConst cellValues(const size_t& i_cell) const
+  {
+    const ConnectivityMatrix::size_type& cell_begin = m_node_id_per_cell_matrix.row_map[i_cell];
+    const ConnectivityMatrix::size_type& cell_end = m_node_id_per_cell_matrix.row_map[i_cell+1];
+    return SubViewConst(m_values, cell_begin, cell_end);
+  }
+
   NodeByCellData(const ConnectivityMatrix& node_id_per_cell_matrix)
       : m_node_id_per_cell_matrix(node_id_per_cell_matrix),
         m_values("values", m_node_id_per_cell_matrix.entries.extent(0))