Refactor ElementMap, removing its copy-on-write feature

src/testing/graph_topology_addition_testing.rs

@@ -15,8 +15,10 @@ macro_rules! graph_topology_addition_tests {
             reserve_edges_does_not_affect_vertex_capacity,
             add_vertex,
             add_edge,
-            vertex_map_new_vertex,
-            edge_map_new_edge,
+            sync_vertex_map_after_add,
+            sync_edge_map_after_add,
+            sync_vertex_map_preserves_values,
+            sync_edge_map_preserves_values,
         );
     };
 
@@ -122,31 +124,68 @@ where
     assert_ne!(graph.add_edge(u, v), e, "unexpected duplicate edge");
 }
 
-pub fn vertex_map_new_vertex<G: GraphTopologyAddition>() {
+pub fn sync_vertex_map_after_add<G: GraphTopologyAddition>() {
     let mut graph = G::default();
     let mut map = graph.vertex_map(27);
+    let u = graph.add_vertex();
     let v = graph.add_vertex();
+    graph.sync_vertex_map(&mut map);
     assert_eq!(
-        map[v], 27,
+        map[u], 27,
         "unexpected value from default map read for new vertex"
     );
-    map[v] = 9;
+    map[u] = 9;
     assert_eq!(
-        map[v], 9,
+        map[u], 9,
         "unexpected value from map read after write for new vertex"
     );
+    assert_eq!(
+        map[v], 27,
+        "unexpected value from default map read for second new vertex"
+    );
 }
 
-pub fn edge_map_new_edge<G: GraphTopologyAddition>() {
+pub fn sync_edge_map_after_add<G: GraphTopologyAddition>() {
     let mut graph = G::default();
     let u = graph.add_vertex();
     let v = graph.add_vertex();
     let mut map = graph.edge_map(28);
     let e = graph.add_edge(u, v);
-    assert_eq!(map[e], 28);
+    let f = graph.add_edge(u, v);
+    graph.sync_edge_map(&mut map);
+    assert_eq!(
+        map[e], 28,
+        "unexpected value from default map read for new edge"
+    );
     map[e] = 8;
     assert_eq!(
         map[e], 8,
         "unexpected value from map read after write for new edge"
     );
+    assert_eq!(
+        map[f], 28,
+        "unexpected value from default map read for second new edge"
+    );
+}
+
+pub fn sync_vertex_map_preserves_values<G: GraphTopologyAddition>() {
+    let mut graph = G::default();
+    let v = graph.add_vertex();
+    let mut map = graph.vertex_map(0);
+    map[v] = 5;
+    graph.reserve_vertices(20);
+    graph.sync_vertex_map(&mut map);
+    assert_eq!(map[v], 5, "sync should not change existing map values");
+}
+
+pub fn sync_edge_map_preserves_values<G: GraphTopologyAddition>() {
+    let mut graph = G::default();
+    let u = graph.add_vertex();
+    let v = graph.add_vertex();
+    let e = graph.add_edge(u, v);
+    let mut map = graph.edge_map(0);
+    map[e] = 6;
+    graph.reserve_edges(20);
+    graph.sync_edge_map(&mut map);
+    assert_eq!(map[e], 6, "sync should not change existing map values");
 }