Change GraphTopologyConversion::convert return value to include the new GraphIsomorphism

This allows to convert maps for the converted graph.

src/models/frozen_graph.rs

@@ -3,7 +3,9 @@
 use std::ops::IndexMut;
 
 use crate::maps::ElementMap;
-use crate::traits::{GraphTopology, GraphTopologyConversion, Incidence, IncidenceCursor};
+use crate::traits::{
+    GraphIsomorphism, GraphTopology, GraphTopologyConversion, Incidence, IncidenceCursor,
+};
 
 /// An opaque handle identifying a vertex in a [`FrozenGraph`].
 ///
@@ -77,10 +79,10 @@ impl IncidenceCursor<FrozenGraph> for FrozenGraphIncidenceCursor {
 /// let u = graph.add_vertex();
 /// let v = graph.add_vertex();
 /// let e = graph.add_edge(u, v);
-/// let (graph, vertex_map, edge_map) = FrozenGraph::convert(&graph);
+/// let (graph, isomorphism) = FrozenGraph::convert(&graph);
 ///
 /// // Queries the FrozenGraph instance via the returned map.
-/// assert!(graph.are_adjacent(vertex_map[u], vertex_map[v]));
+/// assert!(graph.are_adjacent(isomorphism.vertex(u), isomorphism.vertex(v)));
 /// ```
 ///
 /// # Time and space complexity
@@ -193,13 +195,7 @@ impl GraphTopology for FrozenGraph {
 }
 
 impl GraphTopologyConversion for FrozenGraph {
-    fn convert<G: GraphTopology>(
-        source: &G,
-    ) -> (
-        Self,
-        ElementMap<G::Vertex, Vertex>,
-        ElementMap<G::Edge, Edge>,
-    ) {
+    fn convert<G: GraphTopology>(source: &G) -> (Self, GraphIsomorphism<G, Self>) {
         // Builds vertex list with sentinel and vertex map.
         let mut vertex_map = source.vertex_map(Vertex(usize::MAX));
         let mut vertices = Vec::with_capacity(source.vertex_count() + 1);
@@ -237,14 +233,12 @@ impl GraphTopologyConversion for FrozenGraph {
             }
         }
 
-        (
-            Self {
-                vertices,
-                incidences,
-            },
-            vertex_map,
-            edge_map,
-        )
+        let result = Self {
+            vertices,
+            incidences,
+        };
+        let iso = GraphIsomorphism::new(&result, vertex_map, edge_map);
+        (result, iso)
     }
 }