Add weight parameter for Dijkstra's algorithm, add unweighted variants (unused)

src/algorithms.rs

@@ -27,12 +27,13 @@ pub struct DijkstraResult<V: Copy> {
     pub predecessors: VertexMap<V, Option<V>>,
 }
 
-pub fn dijkstra<G>(graph: &G, source: G::Vertex) -> DijkstraResult<G::Vertex>
+pub fn dijkstra<G, W>(graph: &G, source: G::Vertex, weight: W) -> DijkstraResult<G::Vertex>
 where
     G: GraphTopology,
+    W: Fn(G::Edge) -> u32,
 {
     let mut predecessors = graph.vertex_map(None);
-    let distances = dijkstra_impl(graph, source, |neighbor, predecessor| {
+    let distances = dijkstra_impl(graph, source, weight, |neighbor, predecessor| {
         predecessors[neighbor] = Some(predecessor);
     });
     DijkstraResult {
@@ -41,21 +42,44 @@ where
     }
 }
 
-pub fn dijkstra_distances<G>(graph: &G, source: G::Vertex) -> VertexMap<G::Vertex, Option<u32>>
+pub fn dijkstra_unweighted<G>(graph: &G, source: G::Vertex) -> DijkstraResult<G::Vertex>
 where
     G: GraphTopology,
 {
-    dijkstra_impl(graph, source, |_, _| {})
+    dijkstra(graph, source, |_| 1)
 }
 
-// TODO: Add a way to provide custom edge weights for Dijkstra's algorithm.
-fn dijkstra_impl<G, F>(
+pub fn dijkstra_distances<G, W>(
     graph: &G,
     source: G::Vertex,
+    weight: W,
+) -> VertexMap<G::Vertex, Option<u32>>
+where
+    G: GraphTopology,
+    W: Fn(G::Edge) -> u32,
+{
+    dijkstra_impl(graph, source, weight, |_, _| {})
+}
+
+pub fn dijkstra_distances_unweighted<G>(
+    graph: &G,
+    source: G::Vertex,
+) -> VertexMap<G::Vertex, Option<u32>>
+where
+    G: GraphTopology,
+{
+    dijkstra_distances(graph, source, |_| 1)
+}
+
+fn dijkstra_impl<G, W, F>(
+    graph: &G,
+    source: G::Vertex,
+    weight: W,
     mut on_relax: F,
 ) -> VertexMap<G::Vertex, Option<u32>>
 where
     G: GraphTopology,
+    W: Fn(G::Edge) -> u32,
     F: FnMut(G::Vertex, G::Vertex),
 {
     let mut distances = graph.vertex_map(None);
@@ -69,6 +93,7 @@ where
 
     while let Some(v) = heap.pop() {
         for neighbor in graph.neighbors(v.vertex) {
+            // TODO: Use custom edge weights in Dijkstra's algorithm.
             let edge_weight = 1;
             let new_distance = distances[v.vertex].unwrap() + edge_weight;
             if match distances[neighbor] {

tests/dijkstra.rs

@@ -6,7 +6,7 @@ use grapherity::traits::GraphTopology;
 fn dijkstra_single_vertex() {
     let mut graph = AppendGraph::new();
     let v1 = graph.add_vertex();
-    let result = algorithms::dijkstra(&graph, v1);
+    let result = algorithms::dijkstra_unweighted(&graph, v1);
     assert_eq!(
         result.distances[v1],
         Some(0),
@@ -23,7 +23,7 @@ fn dijkstra_disconnected() {
     let mut graph = AppendGraph::new();
     let v1 = graph.add_vertex();
     let v2 = graph.add_vertex();
-    let result = algorithms::dijkstra(&graph, v1);
+    let result = algorithms::dijkstra_unweighted(&graph, v1);
     assert_eq!(
         result.distances[v1],
         Some(0),
@@ -46,7 +46,7 @@ fn dijkstra_disconnected() {
 #[test]
 fn dijkstra() {
     let (graph, vertices) = make_test_graph();
-    let result = algorithms::dijkstra(&graph, vertices[0]);
+    let result = algorithms::dijkstra_unweighted(&graph, vertices[0]);
     let expected_distances_from_v0 = [
         Some(0),
         Some(1),
@@ -90,7 +90,7 @@ fn dijkstra() {
 fn dijkstra_distances_single_vertex() {
     let mut graph = AppendGraph::new();
     let v1 = graph.add_vertex();
-    let distances = algorithms::dijkstra_distances(&graph, v1);
+    let distances = algorithms::dijkstra_distances_unweighted(&graph, v1);
     assert_eq!(
         distances[v1],
         Some(0),
@@ -103,7 +103,7 @@ fn dijkstra_distances_disconnected() {
     let mut graph = AppendGraph::new();
     let v1 = graph.add_vertex();
     let v2 = graph.add_vertex();
-    let distances = algorithms::dijkstra_distances(&graph, v1);
+    let distances = algorithms::dijkstra_distances_unweighted(&graph, v1);
     assert_eq!(
         distances[v1],
         Some(0),
@@ -118,7 +118,7 @@ fn dijkstra_distances_disconnected() {
 #[test]
 fn dijkstra_distances() {
     let (graph, vertices) = make_test_graph();
-    let distances = algorithms::dijkstra_distances(&graph, vertices[0]);
+    let distances = algorithms::dijkstra_distances_unweighted(&graph, vertices[0]);
     let expected_distances_from_v0 = [
         Some(0),
         Some(1),