barebones module.parent implementation

[goto-bus-stop]

if the module has a parent, rewrites module.parent to {}. else rewrites it to null.

this supports the case where module.parent is only used to check for whether the module is being invoked directly, or required by some other module.

[goto-bus-stop]

Maybe could detect more complex uses and do something similar to cyclical modules, with a lazy wrapper.

// xyz.js
module.exports = module.parent.exports
// app.js
exports.app = function () {
  console.log('app')
}
require('./xyz').app()

→

var _$withParent = function (factory) {
  var cache
  return function (parent) {
    if (!cache) {
      var exports = {}, module = { exports: exports }
      cache = factory(module, exports, parent)
    }
    return cache
  }
}
// xyz.js
var _$xyz_1 = _$withParent(function (module, exports, parent) {
  module.exports = parent.exports
})
// app.js
var _$app_2 = {}
_$app_2.app = function () {
  console.log('app')
}
_$xyz_1({ filename: 'app.js'/* maybe? */, exports: _$app_2 }).app()

[goto-bus-stop]

this is a good start and has parity with browser-pack so i'll just do this for now.