Add VertexMap to attach data to vertices

src/models/graph.rs

@@ -1,5 +1,6 @@
 use typed_generational_arena::{Arena, Index};
 
+use crate::maps::VertexMap;
 use crate::traits::{GraphTopology, GraphTopologyDeletion};
 
 type Vertex = Index<VertexIncidenceHeader, usize, usize>;
@@ -162,6 +163,14 @@ impl GraphTopology for Graph {
         self.incidences.len() / 2
     }
 
+    fn vertex_capacity(&self) -> usize {
+        self.vertices.capacity()
+    }
+
+    fn vertex_map<T: Clone>(&self, default: T) -> VertexMap<Self::Vertex, T> {
+        VertexMap::new(default, |v| v.arr_idx(), self.vertex_capacity())
+    }
+
     fn degree(&self, v: Self::Vertex) -> usize {
         self.vertices[v].incidence_count
     }