'use strict';

var assert = require('assert');

/**
 * A empty function.
 *
 * @return {Function}
 * @public
 */
exports.noop = function noop() {};

/**
 * Get a function parameter's names.
 *
 * @param {Function} func
 * @param {Boolean} [useCache], default is true
 * @return {Array} names
 */
exports.getParamNames = function getParamNames(func, cache) {
  var type = typeof func;
  assert(type === 'function', `The "func" must be a function. Received type "${type}"`);

  cache = cache !== false;
  if (cache && func.__cache_names) {
    return func.__cache_names;
  }
  var str = func.toString();
  var names = str.slice(str.indexOf('(') + 1, str.indexOf(')')).match(/([^\s,]+)/g) || [];
  func.__cache_names = names;
  return names;
};
