Add support for edges in "to_dot" function of OpticScenery

examples/opticscenery.rs

@@ -11,7 +11,9 @@ fn main() {
     scenery.set_description("OpticScenery demo".into());
     println!("default opticscenery: {:?}", scenery);
     println!("export to `dot` format: {}", scenery.to_dot());
-    scenery.add_node(OpticNode::new("my optic", Box::new(NodeDummy)));
+    let node1=scenery.add_node(OpticNode::new("my optic", Box::new(NodeDummy)));
+    let node2=scenery.add_node(OpticNode::new("my other optic", Box::new(NodeDummy)));
+    scenery.connect_nodes(node1, node2);
     let path = "graph.dot";
     let mut output = File::create(path).unwrap();
     write!(output, "{}", scenery.to_dot()).unwrap();

src/optic_scenery.rs

@@ -55,10 +55,12 @@ impl OpticScenery {
         for node in self.g.node_weights() {
             dot_string += &node.to_dot();
         }
-        dot_string += "\n";
-        // for edge in self.g.edge_indices() {
-        
-        // }
+        for edge in self.g.edge_indices() {
+            let end_nodes = self.g.edge_endpoints(edge).unwrap();
+            let node1 = self.g.node_weight(end_nodes.0).unwrap();
+            let node2 = self.g.node_weight(end_nodes.1).unwrap();
+            dot_string.push_str(&format!("  \"{}\" -> \"{}\"\n", node1.name(), node2.name()));
+        }
         dot_string += "}";
         dot_string
     }