Add "algorithms" and "models" modules for existing code and related todos

src/algorithms.rs

@@ -0,0 +1,70 @@
+use std::cmp::Ordering;
+use std::collections::BinaryHeap;
+
+use crate::models::Graph;
+use crate::models::Vertex;
+
+#[derive(PartialEq, Eq)]
+struct DistanceOrderedVertex {
+    distance: u32,
+    vertex: Vertex,
+}
+
+impl PartialOrd for DistanceOrderedVertex {
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        Some(self.distance.cmp(&other.distance))
+    }
+}
+
+impl Ord for DistanceOrderedVertex {
+    fn cmp(&self, other: &Self) -> Ordering {
+        other.distance.cmp(&self.distance)
+    }
+}
+
+// TODO: Maybe introduce a return struct type for Dijkstra's algorithm?
+// TODO: Maybe variant of Dijkstra's algorithm without predecessors?
+pub fn dijkstra(graph: &Graph, source: Vertex) -> (Vec<Option<u32>>, Vec<Option<Vertex>>) {
+    let mut distances = vec![None; graph.vertex_count()];
+    let mut predecessors = vec![None; graph.vertex_count()];
+    let mut heap = BinaryHeap::new();
+
+    distances[source.0] = Some(0);
+    heap.push(DistanceOrderedVertex {
+        vertex: source,
+        distance: 0,
+    });
+    while let Some(v) = heap.pop() {
+        // TODO: Simplify with a neighbor iterator.
+        // Finds the first neighbor of v.
+        let Some(mut incidence) = graph.incidence_headers[v.vertex.0].first_incidence else {
+            break;
+        };
+        loop {
+            // Processes one neighbor of v.
+            let neighbor = graph.incidence_vertices[incidence.0];
+            // TODO: Add a way to provide custom edge weights for Dijkstra's algorithm.
+            let edge_weight = 1;
+            let new_distance = distances[v.vertex.0].unwrap() + edge_weight;
+            if match distances[neighbor.0] {
+                None => true,
+                Some(old_distance) if old_distance > new_distance => true,
+                _ => false,
+            } {
+                distances[neighbor.0] = Some(new_distance);
+                predecessors[neighbor.0] = Some(v.vertex);
+                heap.push(DistanceOrderedVertex {
+                    vertex: neighbor,
+                    distance: new_distance,
+                });
+            }
+
+            // Finds next neighbor of v.
+            let Some(next) = graph.next_incidences[incidence.0] else {
+                break;
+            };
+            incidence = next;
+        }
+    }
+    (distances, predecessors)
+}

src/main.rs

@@ -1,148 +1,8 @@
-use std::cmp::Ordering;
+mod algorithms;
-use std::collections::BinaryHeap;
+mod models;
 
-#[derive(Copy, Clone, PartialEq, Eq, Debug)]
+use models::Graph;
-struct Vertex(usize);
+use models::Vertex;
-
-#[derive(Copy, Clone, PartialEq, Eq)]
-struct Incidence(usize);
-
-struct VertexIncidenceHeader {
-    incidence_count: usize,
-    first_incidence: Option<Incidence>,
-}
-
-// TODO: Visibility of Graph members.
-struct Graph {
-    // TODO: Index 'incidence_headers' by a 'Vertex' instead of 'Vertex.0'?
-    incidence_headers: Vec<VertexIncidenceHeader>,
-    next_incidences: Vec<Option<Incidence>>,
-    incidence_vertices: Vec<Vertex>,
-}
-
-// TODO: Add iterator of vertices.
-// TODO: Add iterator of edges.
-// TODO: Add iterator of vertex neighbors, see 'fn add_adjacent()'.
-impl Graph {
-    fn vertex_count(&self) -> usize {
-        self.incidence_headers.len()
-    }
-
-    fn edge_count(&self) -> usize {
-        self.next_incidences.len() / 2
-    }
-
-    fn degree(&self, v: Vertex) -> usize {
-        self.incidence_headers[v.0].incidence_count
-    }
-
-    // TODO: 'fn are_adjacent()' could probably be done with a neighbor vertex iterator.
-    fn are_adjacent(&self, v1: Vertex, v2: Vertex) -> bool {
-        let Some(mut incidence) = self.incidence_headers[v1.0].first_incidence else {
-            return false;
-        };
-        loop {
-            if self.incidence_vertices[incidence.0] == v2 {
-                return true;
-            }
-            let Some(next) = self.next_incidences[incidence.0] else {
-                return false;
-            };
-            incidence = next;
-        }
-    }
-
-    // TODO: 'fn add_vertex()' should not be publicly accessible for all graph implementations.
-    // TODO: 'fn add_vertex()' needs variants for custom vertex data.
-    fn add_vertex(&mut self) -> Vertex {
-        self.incidence_headers.push(VertexIncidenceHeader {
-            incidence_count: 0,
-            first_incidence: None,
-        });
-        Vertex(self.incidence_headers.len() - 1)
-    }
-
-    // TODO: 'fn add_edge()' should not be publicly accessible for all graph implementations.
-    // TODO: 'fn add_edge()' needs variants for custom edge data.
-    fn add_edge(&mut self, v1: Vertex, v2: Vertex) {
-        self.add_incidence(v1, v2);
-        self.add_incidence(v2, v1);
-    }
-
-    fn add_incidence(&mut self, v1: Vertex, v2: Vertex) {
-        self.incidence_vertices.push(v2);
-        self.next_incidences
-            .push(self.incidence_headers[v1.0].first_incidence.take());
-        self.incidence_headers[v1.0].incidence_count += 1;
-        self.incidence_headers[v1.0].first_incidence =
-            Some(Incidence(self.incidence_vertices.len() - 1));
-    }
-}
-
-#[derive(PartialEq, Eq)]
-struct DistanceOrderedVertex {
-    distance: u32,
-    vertex: Vertex,
-}
-
-impl PartialOrd for DistanceOrderedVertex {
-    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
-        Some(self.distance.cmp(&other.distance))
-    }
-}
-
-impl Ord for DistanceOrderedVertex {
-    fn cmp(&self, other: &Self) -> Ordering {
-        other.distance.cmp(&self.distance)
-    }
-}
-
-// TODO: Maybe introduce a return struct type for Dijkstra's algorithm?
-// TODO: Maybe variant of Dijkstra's algorithm without predecessors?
-fn dijkstra(graph: &Graph, source: Vertex) -> (Vec<Option<u32>>, Vec<Option<Vertex>>) {
-    let mut distances = vec![None; graph.vertex_count()];
-    let mut predecessors = vec![None; graph.vertex_count()];
-    let mut heap = BinaryHeap::new();
-
-    distances[source.0] = Some(0);
-    heap.push(DistanceOrderedVertex {
-        vertex: source,
-        distance: 0,
-    });
-    while let Some(v) = heap.pop() {
-        // TODO: Simplify with a neighbor iterator.
-        // Finds the first neighbor of v.
-        let Some(mut incidence) = graph.incidence_headers[v.vertex.0].first_incidence else {
-            break;
-        };
-        loop {
-            // Processes one neighbor of v.
-            let neighbor = graph.incidence_vertices[incidence.0];
-            // TODO: Add a way to provide custom edge weights for Dijkstra's algorithm.
-            let edge_weight = 1;
-            let new_distance = distances[v.vertex.0].unwrap() + edge_weight;
-            if match distances[neighbor.0] {
-                None => true,
-                Some(old_distance) if old_distance > new_distance => true,
-                _ => false,
-            } {
-                distances[neighbor.0] = Some(new_distance);
-                predecessors[neighbor.0] = Some(v.vertex);
-                heap.push(DistanceOrderedVertex {
-                    vertex: neighbor,
-                    distance: new_distance,
-                });
-            }
-
-            // Finds next neighbor of v.
-            let Some(next) = graph.next_incidences[incidence.0] else {
-                break;
-            };
-            incidence = next;
-        }
-    }
-    (distances, predecessors)
-}
 
 fn main() {
     // TODO: Move this graph example into one or more tests.
@@ -221,7 +81,7 @@ fn main() {
         );
     }
 
-    let (distances, predecessors) = dijkstra(&graph, vertices[0]);
+    let (distances, predecessors) = algorithms::dijkstra(&graph, vertices[0]);
     let expected_distances_from_v0 = [
         Some(0),
         Some(1),

src/models.rs

@@ -0,0 +1,81 @@
+// TODO: Vertex value must not be public.
+#[derive(Copy, Clone, PartialEq, Eq, Debug)]
+pub struct Vertex(pub usize);
+
+// TODO: Incidence value must not be public.
+// TODO: Incidence must not be public.
+#[derive(Copy, Clone, PartialEq, Eq)]
+pub struct Incidence(pub usize);
+
+// TODO: VertexIncidenceHeader and its fields must not be public, but without iterators there is currently no other way to access vertex incidences.
+pub struct VertexIncidenceHeader {
+    incidence_count: usize,
+    pub first_incidence: Option<Incidence>,
+}
+
+// TODO: Graph fields must not be public.
+pub struct Graph {
+    // TODO: Index 'incidence_headers' by a 'Vertex' instead of 'Vertex.0'?
+    pub incidence_headers: Vec<VertexIncidenceHeader>,
+    pub next_incidences: Vec<Option<Incidence>>,
+    pub incidence_vertices: Vec<Vertex>,
+}
+
+// TODO: Add iterator of vertices.
+// TODO: Add iterator of edges.
+// TODO: Add iterator of vertex neighbors, see 'fn add_adjacent()'.
+impl Graph {
+    pub fn vertex_count(&self) -> usize {
+        self.incidence_headers.len()
+    }
+
+    pub fn edge_count(&self) -> usize {
+        self.next_incidences.len() / 2
+    }
+
+    pub fn degree(&self, v: Vertex) -> usize {
+        self.incidence_headers[v.0].incidence_count
+    }
+
+    // TODO: 'fn are_adjacent()' could probably be done with a neighbor vertex iterator.
+    pub fn are_adjacent(&self, v1: Vertex, v2: Vertex) -> bool {
+        let Some(mut incidence) = self.incidence_headers[v1.0].first_incidence else {
+            return false;
+        };
+        loop {
+            if self.incidence_vertices[incidence.0] == v2 {
+                return true;
+            }
+            let Some(next) = self.next_incidences[incidence.0] else {
+                return false;
+            };
+            incidence = next;
+        }
+    }
+
+    // TODO: 'fn add_vertex()' should not be publicly accessible for all graph implementations.
+    // TODO: 'fn add_vertex()' needs variants for custom vertex data.
+    pub fn add_vertex(&mut self) -> Vertex {
+        self.incidence_headers.push(VertexIncidenceHeader {
+            incidence_count: 0,
+            first_incidence: None,
+        });
+        Vertex(self.incidence_headers.len() - 1)
+    }
+
+    // TODO: 'fn add_edge()' should not be publicly accessible for all graph implementations.
+    // TODO: 'fn add_edge()' needs variants for custom edge data.
+    pub fn add_edge(&mut self, v1: Vertex, v2: Vertex) {
+        self.add_incidence(v1, v2);
+        self.add_incidence(v2, v1);
+    }
+
+    fn add_incidence(&mut self, v1: Vertex, v2: Vertex) {
+        self.incidence_vertices.push(v2);
+        self.next_incidences
+            .push(self.incidence_headers[v1.0].first_incidence.take());
+        self.incidence_headers[v1.0].incidence_count += 1;
+        self.incidence_headers[v1.0].first_incidence =
+            Some(Incidence(self.incidence_vertices.len() - 1));
+    }
+}