Add VertexMap to attach data to vertices

src/models/append_graph.rs

@@ -1,3 +1,4 @@
+use crate::maps::VertexMap;
 use crate::traits::GraphTopology;
 
 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
@@ -83,6 +84,14 @@ impl GraphTopology for AppendGraph {
         self.incidences.len() / 2
     }
 
+    fn vertex_capacity(&self) -> usize {
+        self.vertices.len()
+    }
+
+    fn vertex_map<T: Clone>(&self, default: T) -> VertexMap<Self::Vertex, T> {
+        VertexMap::new(default, |v| v.0, self.vertex_capacity())
+    }
+
     fn degree(&self, v: Self::Vertex) -> usize {
         self.vertices[v.0].incidence_count
     }