[centrality] added comments to driver code

include/metrics/betweennessCentrality.hpp

@@ -74,30 +74,45 @@ pgr_betweennesscentrality(
 template <class G>
 class Pgr_metrics {
  public:
+    /** @name betweennessCentrality
+		 *  @{
+		 *
+		 */
+
+    /** @brief betweennessCentrality function
+		 *
+		 * It does all the processing and returns the results.
+		 *
+		 * @param graph  the graph containing the edges
+		 *
+		 * @see [boost::brandes_betweenness_centrality]
+		 * (https://www.boost.org/doc/libs/1_85_0/libs/graph/doc/betweenness_centrality.html)
+		 */		 
      using Graph = typename G::B_G;
-     using Vertex = typename G::V;
+     using V = typename G::V;
+     using E = typename G::E;
      typedef typename boost::graph_traits<Graph>::directed_category directed_category;
 
      void betweennessCentrality(
              const G &graph,
              size_t &result_tuple_count,
              IID_t_rt **postgres_rows ) {
          std::vector<double> centrality(boost::num_vertices(graph.graph), 0.0);
-
+         // stores the centrality values for all vertices of the graph
          auto centrality_map = boost::make_iterator_property_map(centrality.begin(),
                                                                  boost::get(boost::vertex_index, graph.graph));
 
-
          /* abort in case of an interruption occurs (e.g. the query is being cancelled) */
          CHECK_FOR_INTERRUPTS();
          boost::brandes_betweenness_centrality(
                  graph.graph,
-                 centrality_map);
-
+                 centrality_map
+         );
          if (boost::num_vertices(graph.graph) > 2) {
              boost::relative_betweenness_centrality(
                 graph.graph,
-                centrality_map);
+                centrality_map
+				     );
          }
 
          generate_results(graph, centrality, result_tuple_count, postgres_rows);