Support anonymous and arrow callbacks

[ivov]

This PR enables evaluation for anonymous and arrow callbacks, which currently fail with Expression is not valid: missing ) after argument list and Expression is not valid: Malformed arrow function parameter list, respectively.

Support added for:

• same-line anonymous callback
• single-line anonymous callback
• multi-line anonymous callback
• same-line arrow callback, immediate return
• same-line arrow callback, standard return
• single-line arrow callback

const tmpl = require('./dist/tmpl.js').tmpl;

const anon1 = tmpl('{ [1, 2, 3].filter(function (v) { return v > 2 }) }');
const anon2 = tmpl(`{ [1, 2, 3].filter(function (v) {
  return v > 2
})}`);
const anon3 = tmpl(`{ [1, 2, 3].filter(function (v) {
  const a = 1;
  return v > 2
})}`);

const arrow1 = tmpl('{ [1, 2, 3].filter((v) => v > 2) }');
const arrow2 = tmpl('{ [1, 2, 3].filter((v) => { return v > 2 }) }');
const arrow3 = tmpl(`{ [1, 2, 3].filter((v) => {
  return v > 2
}) }`);

console.log(anon1);  // [3]
console.log(anon2);  // [3]
console.log(anon3);  // [3]
console.log(arrow1); // [3]
console.log(arrow2); // [3]
console.log(arrow3); // [3]

Note:

• This failing test is pre-existent: expressions are just regular JavaScript
• Multi-line arrow callbacks are unsupported for now, to reduce scope.

[csuermann]

Hi @ivov,

As expressions are such a critical feature of n8n, it would be good to have decent test coverage for any changes we do. Would you agree?

[ivov]

Done. For reference there were no tests at all for expressions.