Add BfsImplResult and DfsImplResult as named return structs

src/algorithms.rs

@@ -122,12 +122,12 @@ where
     G: GraphTopology,
 {
     let mut predecessors = graph.vertex_map(None);
-    let (distances, _) = bfs_impl(graph, source, |neighbor, predecessor| {
+    let result = bfs_impl(graph, source, |neighbor, predecessor| {
         predecessors[neighbor] = Some(predecessor);
         true
     });
     BfsResult {
-        distances,
+        distances: result.distances,
         predecessors,
     }
 }
@@ -136,7 +136,7 @@ pub fn bfs_distances<G>(graph: &G, source: G::Vertex) -> VertexMap<G::Vertex, Op
 where
     G: GraphTopology,
 {
-    bfs_impl(graph, source, |_, _| true).0
+    bfs_impl(graph, source, |_, _| true).distances
 }
 
 pub fn bfs_find<G>(graph: &G, source: G::Vertex, target: G::Vertex) -> Option<u32>
@@ -154,14 +154,15 @@ where
     if predicate(source) {
         return Some((source, 0));
     }
-    bfs_impl(graph, source, |neighbor, _| !predicate(neighbor)).1
+    bfs_impl(graph, source, |neighbor, _| !predicate(neighbor)).found
 }
 
-fn bfs_impl<G, F>(
+struct BfsImplResult<V: Copy> {
-    graph: &G,
+    distances: VertexMap<V, Option<u32>>,
-    source: G::Vertex,
+    found: Option<(V, u32)>,
-    mut on_discover: F,
+}
-) -> (VertexMap<G::Vertex, Option<u32>>, Option<(G::Vertex, u32)>)
+
+fn bfs_impl<G, F>(graph: &G, source: G::Vertex, mut on_discover: F) -> BfsImplResult<G::Vertex>
 where
     G: GraphTopology,
     F: FnMut(G::Vertex, G::Vertex) -> bool,
@@ -178,13 +179,19 @@ where
                 let distance = distances[v].unwrap() + 1;
                 distances[neighbor] = Some(distance);
                 if !on_discover(neighbor, v) {
-                    return (distances, Some((neighbor, distance)));
+                    return BfsImplResult {
+                        distances,
+                        found: Some((neighbor, distance)),
+                    };
                 }
                 queue.push_back(neighbor);
             }
         }
     }
-    (distances, None)
+    BfsImplResult {
+        distances,
+        found: None,
+    }
 }
 
 pub struct DfsResult<V: Copy> {
@@ -197,12 +204,12 @@ where
     G: GraphTopology,
 {
     let mut predecessors = graph.vertex_map(None);
-    let (visited, _) = dfs_impl(graph, source, |neighbor, predecessor| {
+    let result = dfs_impl(graph, source, |neighbor, predecessor| {
         predecessors[neighbor] = Some(predecessor);
         true
     });
     DfsResult {
-        visited,
+        visited: result.visited,
         predecessors,
     }
 }
@@ -211,7 +218,7 @@ pub fn dfs_visited<G>(graph: &G, source: G::Vertex) -> VertexMap<G::Vertex, bool
 where
     G: GraphTopology,
 {
-    dfs_impl(graph, source, |_, _| true).0
+    dfs_impl(graph, source, |_, _| true).visited
 }
 
 pub fn dfs_find<G>(graph: &G, source: G::Vertex, target: G::Vertex) -> bool
@@ -229,14 +236,15 @@ where
     if predicate(source) {
         return Some(source);
     }
-    dfs_impl(graph, source, |neighbor, _| !predicate(neighbor)).1
+    dfs_impl(graph, source, |neighbor, _| !predicate(neighbor)).found
 }
 
-fn dfs_impl<G, F>(
+struct DfsImplResult<V: Copy> {
-    graph: &G,
+    visited: VertexMap<V, bool>,
-    source: G::Vertex,
+    found: Option<V>,
-    mut on_discover: F,
+}
-) -> (VertexMap<G::Vertex, bool>, Option<G::Vertex>)
+
+fn dfs_impl<G, F>(graph: &G, source: G::Vertex, mut on_discover: F) -> DfsImplResult<G::Vertex>
 where
     G: GraphTopology,
     F: FnMut(G::Vertex, G::Vertex) -> bool,
@@ -248,7 +256,10 @@ where
     while let Some((v, predecessor)) = stack.pop() {
         if let Some(p) = predecessor {
             if !on_discover(v, p) {
-                return (visited, Some(v));
+                return DfsImplResult {
+                    visited,
+                    found: Some(v),
+                };
             }
         }
         for neighbor in graph.adjacent_vertices(v) {
@@ -258,7 +269,10 @@ where
             }
         }
     }
-    (visited, None)
+    DfsImplResult {
+        visited,
+        found: None,
+    }
 }
 
 pub fn dfs_find_path<G>(graph: &G, source: G::Vertex, target: G::Vertex) -> Option<Vec<G::Edge>>