add disconnect function to SimpleGraph

src/edge.rs

@@ -1 +1,3 @@
-pub trait Edge {}
+pub trait Edge {
+    type HANDLE;
+}

src/graph.rs

@@ -7,11 +7,11 @@ pub trait Graph<V: Vertex, E: Edge> {
     // TODO: figure out a way to modify self? is that even needed?
     // same for `disconnect()`
     // fn connect(vertex_1: &V, vertex_2: &V) -> E;
-    fn connect(&mut self, vertex_1: V::HANDLE, vertex_2: V::HANDLE);
+    fn connect(&mut self, vertex_1: V::HANDLE, vertex_2: V::HANDLE) -> E::HANDLE;
 
     // disconnect two nodes, and return the old edge
     // fn disconnect(vertex_1: &V, vertex_2: &V) -> E;
-    fn disconnect(&mut self, vertex_1: V::HANDLE, vertex_2: V::HANDLE);
+    fn disconnect(&mut self, edge: E::HANDLE);
 
     // get the degree of a given vertex - possibly put this in a GraphUtil trait?
     fn degree(vertex: V::HANDLE) -> usize;

src/test.rs

@@ -8,7 +8,9 @@ struct SimpleEdge {
     v2: usize,
 }
 
-impl Edge for SimpleEdge {}
+impl Edge for SimpleEdge {
+    type HANDLE = usize;
+}
 
 struct SimpleVertex {
     id: usize,
@@ -32,16 +34,24 @@ struct SimpleGraph {
 impl SimpleGraph {}
 
 impl<'a> Graph<SimpleVertex, SimpleEdge> for SimpleGraph {
-    fn connect(&mut self, vertex_1: usize, vertex_2: usize) {
+    fn connect(&mut self, vertex_1: usize, vertex_2: usize) -> usize {
+        let id = self.edges.len();
         self.edges.push(SimpleEdge {
-            id: self.edges.len(),
+            id: id.clone(),
             v1: vertex_1,
             v2: vertex_2,
         });
+        id
     }
 
-    fn disconnect(&mut self, vertex_1: usize, vertex_2: usize) {
-        todo!();
+    // NOTE: this should probably be a failable function... and use a hashmap
+    fn disconnect(&mut self, edge: usize) {
+        for i in (0..self.edges.len()) {
+            if self.edges[i].id == edge {
+                self.edges.remove(i);
+                return;
+            }
+        }
     }
 
     fn degree(vertex: usize) -> usize {
@@ -60,7 +70,7 @@ fn test_connect() {
         vertices: vec![v1, v2],
         edges: Vec::new(),
     };
-    g.connect(0, 1);
+    let _e = g.connect(0, 1);
     assert_eq!(g.edges.len(), 1);
     assert_eq!(g.edges[0].id, 0);
     assert_eq!(g.edges[0].v1, 0);
@@ -69,7 +79,20 @@ fn test_connect() {
 
 #[test]
 fn test_disconnect() {
-    todo!();
+    let v1 = SimpleVertex { id: 0 };
+    let v2 = SimpleVertex { id: 1 };
+    let mut g = SimpleGraph {
+        vertices: vec![v1, v2],
+        edges: Vec::new(),
+    };
+    let e = g.connect(0, 1);
+    assert_eq!(g.edges.len(), 1);
+    assert_eq!(g.edges[0].id, 0);
+    assert_eq!(g.edges[0].v1, 0);
+    assert_eq!(g.edges[0].v2, 1);
+
+    g.disconnect(e);
+    assert_eq!(g.edges.len(), 0);
 }
 
 #[test]