etl/lib/expand.js

const Streamz = require('streamz');
const util = require('util');

function expand(convert) {
  if (!(this instanceof Streamz))
    return new expand(convert);

  Streamz.call(this);

  if (convert == 'uppercase')
    this.convert = function(d) {
      return String(d).toUpperCase();
    };

  else if (convert == 'lowercase')
    this.convert = function(d) {
      return String(d).toLowerCase();
    };

  else
    this.convert = convert;
}

util.inherits(expand,Streamz);

expand.prototype.expand = function(d) {
  for (let key in d) {
    const oldKey = key;
    if (typeof this.convert === 'function')
      key = this.convert(key);

    if (key) {
      if (typeof d[key] === 'object')
        d[key] = this.expand(d[oldKey]);
      else
        d[key] = d[oldKey];
      if (oldKey !== key)
        delete d[oldKey];
    } else
      delete d[oldKey];
  }
  return d;
};

expand.prototype._fn = function(d) {
  return this.expand(Object.create(d));
};

module.exports = expand;