yaml

import { parse, stringify, Document, YAMLMap, Scalar } from 'yaml'; const yamlString = ` # My shopping list - item: Apples quantity: 2 notes: Green ones --- # My second shopping list - item: Milk quantity: 1 unit: gallon `; // Parse a multi-document YAML string, keeping CST nodes for better comment preservation const documents = parse(yamlString, { keepCstNodes: true }) as Document[]; // Access and modify the first document const firstDoc = documents[0]; if (firstDoc && firstDoc.contents instanceof Array) { // Assuming a sequence at root const appleItem = firstDoc.contents[0]; if (appleItem instanceof YAMLMap) { appleItem.set('quantity', 3); // Change quantity appleItem.set('notes', 'Honeycrisp preferred'); // Update notes } } // Access and modify the second document const secondDoc = documents[1]; if (secondDoc && secondDoc.contents instanceof Array) { secondDoc.contents.push(new YAMLMap()); const newItem = secondDoc.contents[secondDoc.contents.length - 1] as YAMLMap; newItem.set('item', 'Bread'); newItem.set('quantity', 1); newItem.set('type', 'whole wheat'); } // Stringify the modified documents back to YAML const modifiedYaml = documents.map(doc => stringify(doc)).join('\n---\n'); console.log('Original YAML:\n', yamlString); console.log('\nModified YAML:\n', modifiedYaml); // Example of parsing a single document with parseDocument and accessing AST const singleDocString = ` user: John Doe roles: - admin - editor active: true `; const doc = parseDocument(singleDocString); if (doc.contents instanceof YAMLMap) { const userNode = doc.contents.get('user'); if (userNode instanceof Scalar) { console.log(`\nUser from single document: ${userNode.value}`); } doc.contents.set('status', 'online'); } console.log('\nModified Single Document with new status:\n', doc.toString());