Add reserve_vertices and reserve_edges to GraphTopologyAddition

src/models/graph.rs

@@ -317,6 +317,14 @@ impl GraphTopologyAddition for Graph {
         self.incidences.capacity() / 2
     }
 
+    fn reserve_vertices(&mut self, additional: usize) {
+        self.vertices.reserve(additional);
+    }
+
+    fn reserve_edges(&mut self, additional: usize) {
+        self.incidences.reserve(additional * 2);
+    }
+
     fn add_vertex(&mut self) -> Self::Vertex {
         self.vertices.insert(VertexIncidenceHeader {
             incidence_count: 0,