feat!: keep track of nodes in a set

Author: JesusTheHun

src/Graph.spec-d.ts

@@ -7,9 +7,9 @@ import { Graph } from './index.js';
 describe('graph types', () => {
   it('should return the given node type', () => {
     const g = new Graph<string, { type: 'foo' | 'bar' }>();
-    const props = g.nodes();
+    const props = g.nodes;
 
-    expectTypeOf(props).toEqualTypeOf<string[]>();
+    expectTypeOf(props).toEqualTypeOf<Set<string>>();
   });
 
   it('should return the given edge properties type', () => {

src/Graph.spec.ts

@@ -11,7 +11,7 @@ describe('Graph', function () {
       graph.addNode('a');
       graph.addNode('b');
 
-      const nodes = graph.nodes();
+      const nodes = graph.nodes;
 
       expect(nodes).toHaveLength(2);
       expect(nodes).toContain('a');
@@ -20,7 +20,7 @@ describe('Graph', function () {
 
     it('Should chain addNode.', function () {
       const graph = new Graph().addNode('a').addNode('b');
-      const nodes = graph.nodes();
+      const nodes = graph.nodes;
 
       expect(nodes).toHaveLength(2);
       expect(nodes).toContain('a');
@@ -34,14 +34,14 @@ describe('Graph', function () {
       graph.removeNode('a');
       graph.removeNode('b');
 
-      const nodes = graph.nodes();
+      const nodes = graph.nodes;
       expect(nodes).toHaveLength(0);
     });
 
     it('Should chain removeNode.', function () {
       const graph = new Graph().addNode('a').addNode('b').removeNode('a').removeNode('b');
 
-      const nodes = graph.nodes();
+      const nodes = graph.nodes;
       expect(nodes).toHaveLength(0);
     });
 
@@ -64,7 +64,7 @@ describe('Graph', function () {
       expect(adjacentNodes).toHaveLength(1);
       expect(adjacentNodes?.has('b')).toBe(true);
 
-      const nodes = graph.nodes();
+      const nodes = graph.nodes;
       expect(nodes).toHaveLength(2);
       expect(nodes).toContain('a');
       expect(nodes).toContain('b');
@@ -99,7 +99,7 @@ describe('Graph', function () {
       graph.addEdge('a', 'b');
       graph.removeEdge('a', 'b');
 
-      const nodes = graph.nodes();
+      const nodes = graph.nodes;
       expect(nodes).toHaveLength(2);
       expect(nodes).toContain('a');
       expect(nodes).toContain('b');
@@ -123,7 +123,7 @@ describe('Graph', function () {
     it('Should return undefined for unknown nodes.', function () {
       const graph = new Graph();
       expect(graph.adjacent('a')).toEqual(undefined);
-      expect(graph.nodes()).toHaveLength(0);
+      expect(graph.nodes).toHaveLength(0);
     });
 
     it('Should do nothing if removing an edge that does not exist.', function () {

src/Graph.ts

@@ -3,6 +3,11 @@ import { EdgeWeight, SerializedInput } from './types.js';
 import { deserializeGraph } from './utils/deserializeGraph.js';
 
 export class Graph<Node = string, LinkProps = never> {
+  /**
+   * Contains all the nodes added to the graph.
+   */
+  nodes: Set<Node> = new Set();
+
   /**
    * The adjacency list of the graph.
    */
@@ -33,6 +38,10 @@ export class Graph<Node = string, LinkProps = never> {
    * If node was not already added, this function sets up an empty adjacency list.
    */
   addNode(node: Node): this {
+    if (!this.nodes.has(node)) {
+      this.nodes.add(node);
+    }
+
     if (!this.edges.has(node)) {
       this.edges.set(node, new Set());
     }
@@ -47,6 +56,7 @@ export class Graph<Node = string, LinkProps = never> {
   removeNode(node: Node): this {
     // Remove outgoing edges (and signal that the node no longer exists).
     this.edges.delete(node);
+    this.nodes.delete(node);
 
     // Remove ingoing edges
     for (const adjacentNodes of this.edges.values()) {
@@ -56,28 +66,6 @@ export class Graph<Node = string, LinkProps = never> {
     return this;
   }
 
-  /**
-   * Gets the list of nodes that have been added to the graph.
-   */
-  nodes(): Node[] {
-    const nodes: Set<Node> = new Set();
-
-    for (const edgeKey of this.edges.keys()) {
-      nodes.add(edgeKey);
-
-      const adjacentNodes = this.edges.get(edgeKey)?.values();
-      if (!adjacentNodes) {
-        throw new Error(`Missing adjacent set for node ${edgeKey}`);
-      }
-
-      for (const adjacentNode of adjacentNodes) {
-        nodes.add(adjacentNode);
-      }
-    }
-
-    return Array.from(nodes);
-  }
-
   /**
    * Gets the adjacent node set for the given node.
    */

src/algorithms/depthFirstSearch/depthFirstSearch.ts

@@ -12,7 +12,7 @@ export function depthFirstSearch<Node, LinkProps>(
   graph: Graph<Node, LinkProps>,
   opts: DepthFirstSearchOptions<NoInfer<Node>, NoInfer<LinkProps>> = {},
 ): Node[] {
-  const { sourceNodes = graph.nodes(), includeSourceNodes = true } = opts;
+  const { sourceNodes = Array.from(graph.nodes), includeSourceNodes = true } = opts;
 
   const visited: Set<Node> = new Set();
   const visiting: Set<Node> = new Set();

src/algorithms/shortestPath/dijkstra.ts

@@ -10,7 +10,7 @@ export function dijkstra<Node>(
   source: NoInfer<Node>,
   destination: NoInfer<Node>,
 ) {
-  const nodes = graph.nodes();
+  const nodes = graph.nodes;
   const { d, p, q } = tracks;
 
   initializeSingleSource(nodes, tracks, source, destination);
@@ -28,14 +28,14 @@ export function dijkstra<Node>(
 }
 
 function initializeSingleSource<Node>(
-  nodes: Node[],
+  nodes: Set<Node>,
   { d }: TraversingTracks<NoInfer<Node>>,
   source: NoInfer<Node>,
   destination: NoInfer<Node>,
 ) {
-  for (const node of nodes) {
+  nodes.forEach((node) => {
     d.set(node, Infinity);
-  }
+  });
 
   if (d.get(source) !== Infinity) {
     throw new Error('Source node is not in the graph');
@@ -49,10 +49,10 @@ function initializeSingleSource<Node>(
 }
 
 function initializePriorityQueue<Node>(
-  nodes: Node[],
+  nodes: Set<Node>,
   { q }: TraversingTracks<NoInfer<Node>>,
 ) {
-  for (let i = 0; i < nodes.length; i++) {
-    q.add(nodes[i]);
-  }
+  nodes.forEach((node) => {
+    q.add(node);
+  });
 }

src/index.ts

@@ -16,3 +16,6 @@ export { cloneGraph } from './utils/cloneGraph.js';
 export { hasCycle } from './utils/hasCycle.js';
 export { serializeGraph } from './utils/serializeGraph.js';
 export { deserializeGraph } from './utils/deserializeGraph.js';
+export { findNodes } from './utils/findNodes.js';
+export { getNode } from './utils/getNode.js';
+export { getFirstNode } from './utils/getFirstNode.js';

src/utils/serializeGraph.ts

@@ -27,7 +27,7 @@ export function serializeGraph<Node, LinkProps, IncludeDefaultWeight extends boo
   const { includeDefaultWeight = false } = opts;
 
   const serialized: Serialized<Node, LinkProps> = {
-    nodes: graph.nodes(),
+    nodes: Array.from(graph.nodes),
     links: [],
   };