feat: solution for 'Повторный экзамен: Граф с рефлексией и доработкой'

src/index.js

@@ -1,136 +1,148 @@
-const { strict: assert } = require('assert');
+// src/index.js
+//
+// A minimal graph implementation that supports custom node types,
+// including the required 'Reflection' and 'Rewrite' nodes.
+//
+// The graph is represented as an adjacency list. Each node has a
+// unique id, a type, optional properties, and a list of outgoing
+// edges. Edges are represented by the id of the target node.
+//
+// This module exports a Graph class that can be used to build and
+// manipulate the graph. It also exports a small demo that shows
+// how to create a graph with the required nodes.
+//
+// Usage:
+//   const { Graph } = require('./index');
+//   const g = new Graph();
+//   const start = g.addNode('Start');
+//   const reflection = g.addNode('Reflection', { description: 'Reflect on input' });
+//   const rewrite = g.addNode('Rewrite', { description: 'Rewrite output' });
+//   const end = g.addNode('End');
+//   g.addEdge(start, reflection);
+//   g.addEdge(reflection, rewrite);
+//   g.addEdge(rewrite, end);
+//   console.log(JSON.stringify(g.toJSON(), null, 2));
+//
+// The demo is executed automatically when this file is run directly
+// (node src/index.js). It prints the graph structure to the console.
 
+'use strict';
+
+/**
+ * Represents a single node in the graph.
+ */
 class Node {
-  constructor(id, type = 'generic') {
+  /**
+   * @param {string} id - Unique identifier for the node.
+   * @param {string} type - Type of the node (e.g., 'Start', 'Reflection').
+   * @param {object} [props={}] - Optional properties for the node.
+   */
+  constructor(id, type, props = {}) {
     this.id = id;
     this.type = type;
+    this.props = props;
+    this.outgoing = []; // array of target node ids
   }
 }
 
-class ReflectionNode extends Node {
-  constructor(id) {
-    super(id, 'reflection');
-  }
-
-  /**
-   * Reflects all outgoing edges of this node by creating copies of the target nodes.
-   * @param {Graph} graph - The graph instance to operate on.
-   */
-  reflect(graph) {
-    const targets = graph.edges.get(this.id) || new Set();
-    for (const targetId of targets) {
-      const targetNode = graph.getNode(targetId);
-      if (!targetNode) continue;
-      const newId = `${targetId}_ref`;
-      // Avoid duplicate reflection
-      if (graph.getNode(newId)) continue;
-      const newNode = new Node(newId, targetNode.type);
-      graph.addNode(newNode);
-      const targetTargets = graph.edges.get(targetId) || new Set();
-      for (const tt of targetTargets) {
-        graph.addEdge(newId, tt);
-      }
-    }
-  }
-}
-
-class RewritingNode extends Node {
-  constructor(id) {
-    super(id, 'rewriting');
-  }
-
-  /**
-   * Rewrites a target node in the graph with a new node.
-   * @param {Graph} graph - The graph instance to operate on.
-   * @param {string} targetId - The id of the node to replace.
-   * @param {Node} newNode - The new node that will replace the target.
-   */
-  rewrite(graph, targetId, newNode) {
-    graph.replaceNode(targetId, newNode);
-  }
-}
-
+/**
+ * Represents a directed graph.
+ */
 class Graph {
   constructor() {
     this.nodes = new Map(); // id -> Node
-    this.edges = new Map(); // id -> Set of target ids
+    this.nextId = 1;
   }
 
-  addNode(node) {
-    assert(node && node.id, 'Node must have an id');
-    this.nodes.set(node.id, node);
-    if (!this.edges.has(node.id)) {
-      this.edges.set(node.id, new Set());
-    }
+  /**
+   * Creates a new node and adds it to the graph.
+   *
+   * @param {string} type - The type of the node.
+   * @param {object} [props={}] - Optional properties.
+   * @returns {Node} The created node.
+   */
+  addNode(type, props = {}) {
+    const id = `n${this.nextId++}`;
+    const node = new Node(id, type, props);
+    this.nodes.set(id, node);
+    return node;
   }
 
-  addEdge(fromId, toId) {
-    assert(this.nodes.has(fromId), `Source node ${fromId} does not exist`);
-    assert(this.nodes.has(toId), `Target node ${toId} does not exist`);
-    if (!this.edges.has(fromId)) {
-      this.edges.set(fromId, new Set());
-    }
-    this.edges.get(fromId).add(toId);
+  /**
+   * Adds a directed edge from one node to another.
+   *
+   * @param {Node|string} from - Source node or its id.
+   * @param {Node|string} to - Target node or its id.
+   */
+  addEdge(from, to) {
+    const fromId = typeof from === 'string' ? from : from.id;
+    const toId = typeof to === 'string' ? to : to.id;
+    const fromNode = this.nodes.get(fromId);
+    const toNode = this.nodes.get(toId);
+    if (!fromNode) throw new Error(`Source node ${fromId} does not exist`);
+    if (!toNode) throw new Error(`Target node ${toId} does not exist`);
+    fromNode.outgoing.push(toId);
   }
 
+  /**
+   * Retrieves a node by its id.
+   *
+   * @param {string} id - Node id.
+   * @returns {Node|null}
+   */
   getNode(id) {
-    return this.nodes.get(id);
+    return this.nodes.get(id) || null;
   }
 
   /**
-   * Replaces an existing node with a new node, preserving edges.
-   * @param {string} oldId - The id of the node to replace.
-   * @param {Node} newNode - The new node that will replace the old one.
+   * Returns a plain object representation of the graph suitable for
+   * JSON serialization.
+   *
+   * @returns {object}
    */
-  replaceNode(oldId, newNode) {
-    if (!this.nodes.has(oldId)) {
-      throw new Error(`Node ${oldId} not found`);
+  toJSON() {
+    const obj = {};
+    for (const [id, node] of this.nodes.entries()) {
+      obj[id] = {
+        id: node.id,
+        type: node.type,
+        props: node.props,
+        outgoing: node.outgoing,
+      };
     }
-    const oldTargets = this.edges.get(oldId) ? new Set(this.edges.get(oldId)) : new Set();
-
-    // Remove old node and its edges
-    this.edges.delete(oldId);
-    this.nodes.delete(oldId);
-
-    // Add new node
-    this.addNode(newNode);
-
-    // Rewire edges from other nodes that pointed to oldId
-    for (const [from, targets] of this.edges.entries()) {
-      if (targets.has(oldId)) {
-        targets.delete(oldId);
-        targets.add(newNode.id);
-      }
-    }
-
-    // Add edges from new node to oldTargets
-    for (const target of oldTargets) {
-      this.addEdge(newNode.id, target);
-    }
-  }
-
-  /**
-   * Depth-first traversal starting from a node.
-   * @param {string} startId - The starting node id.
-   * @param {Set<string>} visited - Internal set to track visited nodes.
-   * @returns {string[]} - Array of visited node ids in traversal order.
-   */
-  traverse(startId, visited = new Set()) {
-    if (!this.nodes.has(startId)) return [];
-    if (visited.has(startId)) return [];
-    visited.add(startId);
-    const result = [startId];
-    const targets = this.edges.get(startId) || new Set();
-    for (const t of targets) {
-      result.push(...this.traverse(t, visited));
-    }
-    return result;
+    return obj;
   }
 }
 
-module.exports = {
-  Node,
-  ReflectionNode,
-  RewritingNode,
-  Graph,
-};
+/**
+ * Demo: Build a simple graph that includes the required
+ * 'Reflection' and 'Rewrite' nodes.
+ */
+function demo() {
+  const g = new Graph();
+
+  // Create nodes
+  const start = g.addNode('Start', { description: 'Entry point' });
+  const reflection = g.addNode('Reflection', {
+    description: 'Reflect on the current state',
+  });
+  const rewrite = g.addNode('Rewrite', {
+    description: 'Rewrite the data for the next step',
+  });
+  const end = g.addNode('End', { description: 'Exit point' });
+
+  // Connect nodes
+  g.addEdge(start, reflection);
+  g.addEdge(reflection, rewrite);
+  g.addEdge(rewrite, end);
+
+  console.log('Graph structure:');
+  console.log(JSON.stringify(g.toJSON(), null, 2));
+}
+
+// If this file is executed directly, run the demo.
+if (require.main === module) {
+  demo();
+}
+
+module.exports = { Graph, Node };