The Tor Browser / file revision

 /* This Source Code Form is subject to the terms of the Mozilla Public

  * License, v. 2.0. If a copy of the MPL was not distributed with this file,

  * You can obtain one at http://mozilla.org/MPL/2.0/. */

 let EXPORTED_SYMBOLS = [

   "AsyncRunner",

 ];

 const { interfaces: Ci, classes: Cc } = Components;

 function AsyncRunner(callbacks) {

   this._callbacks = callbacks;

   this._iteratorQueue = [];

   // This catches errors reported to the console, e.g., via Cu.reportError.

   Cc["@mozilla.org/consoleservice;1"].

     getService(Ci.nsIConsoleService).

     registerListener(this);

 }

 AsyncRunner.prototype = {

   appendIterator: function AR_appendIterator(iter) {

     this._iteratorQueue.push(iter);

   },

   next: function AR_next(/* ... */) {

     if (!this._iteratorQueue.length) {

       this.destroy();

       this._callbacks.done();

       return;

     }

     // send() discards all arguments after the first, so there's no choice here

     // but to send only one argument to the yielder.

     let args = [arguments.length <= 1 ? arguments[0] : Array.slice(arguments)];

     try {

       var val = this._iteratorQueue[0].send.apply(this._iteratorQueue[0], args);

     }

     catch (err if err instanceof StopIteration) {

       this._iteratorQueue.shift();

       this.next();

       return;

     }

     catch (err) {

       this._callbacks.error(err);

     }

     // val is truthy => call next

     // val is an iterator => prepend it to the queue and start on it

     if (val) {

       if (typeof(val) != "boolean")

         this._iteratorQueue.unshift(val);

       this.next();

     }

   },

   destroy: function AR_destroy() {

     Cc["@mozilla.org/consoleservice;1"].

       getService(Ci.nsIConsoleService).

       unregisterListener(this);

     this.destroy = function AR_alreadyDestroyed() {};

   },

   observe: function AR_consoleServiceListener(msg) {

     if (msg instanceof Ci.nsIScriptError &&

         !(msg.flags & Ci.nsIScriptError.warningFlag))

     {

       this._callbacks.consoleError(msg);

     }

   },

 };