blargh.js

Namespace.prototype.bindEmitter = function (source) {
  assert.ok(source.on && source.addListener && source.emit, "can only bind real EEs");

  var namespace = this;
  var contextName = '__' + this.name;

  function capturer(on) {
    return function (event, listener) {
      listener[contextName] = namespace.active;

      var returned = on.call(this, event, listener);

      // what in the seven hells is ReadableStream doing here?
      wrap(this, 'on',          capturer);
      wrap(this, 'addListener', capturer);

      return returned;
    };
  }

  function prepare(handlers) {
    var replacements = [];
    for (var i = 0; i < handlers.length; i++) {
      var handler = handlers[i];
      if (handler[contextName]) {
        replacements.push(namespace.bind(handler, handler[contextName]));
      }
      else {
        replacements.push(handler);
      }
    }

    return replacements;
  }

  function puncher(emit) {
    return function (event) {
      if (!this._events[event]) return emit.apply(this, arguments);

      // setup
      var events = this._events[event];
      if (typeof events === 'function' && events[contextName]) {
        this._events[event] = namespace.bind(events, events[contextName]);
      }
      else if (events.length) {
        this._events[event] = prepare(events);
      }

      // application
      var returned = emit.apply(this, arguments);
      this._events[event] = events;
      return returned;
    };
  }

  wrap(source, 'addListener', capturer);
  wrap(source, 'on',          capturer);
  wrap(source, 'emit',        puncher);
};