const parser = require('@babel/parser');
const generator = require('@babel/generator').default;

const sourceCode = 'const func = ({ str }: {str?:string} = {}) => str;';

console.log(`sourceCode is ${JSON.stringify(sourceCode)}`);

const sourceAST = parser.parse(sourceCode, {
  sourceType: 'module',
  plugins: [
    'jsx',
    'typescript',
  ],
});

const genCode = generator(sourceAST, {
  compact: false,
  concise: false,
  retainLines: true,
  retainFunctionParens: true,
  plugins: [
    'jsx',
    'typescript',
  ],
}).code;

console.log(`genCode is ${JSON.stringify(genCode)}`);