The Tor Browser: toolkit/devtools/async-utils.js@8bccb770b82d (annotated)

toolkit/devtools/async-utils.js@8bccb770b82d (annotated)

toolkit/devtools/async-utils.js

Wed, 31 Dec 2014 13:27:57 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 13:27:57 +0100
branch: TOR_BUG_3246
changeset 6: 8bccb770b82d
permissions: -rw-r--r--

Ignore runtime configuration files generated during quality assurance.

 /* 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/. */
 "use strict";
 /**
  * Helpers for async functions. Async functions are generator functions that are
  * run by Tasks. An async function returns a Promise for the resolution of the
  * function. When the function returns, the promise is resolved with the
  * returned value. If it throws the promise rejects with the thrown error.
  *
  * See Task documentation at https://developer.mozilla.org/en-US/docs/Mozilla/JavaScript_code_modules/Task.jsm.
  */
 let {Cu} = require("chrome");
 let {Task} = require("resource://gre/modules/Task.jsm");
 let {Promise} = require("resource://gre/modules/Promise.jsm");
 /**
  * Create an async function from a generator function.
  *
  * @param Function func
  *        The generator function that to wrap as an async function.
  * @return Function
  *         The async function.
  */
 exports.async = function async(func) {
   return function(...args) {
     return Task.spawn(func.apply(this, args));
   };
 };
 /**
  * Create an async function that only executes once per instance of an object.
  * Once called on a given object, the same promise will be returned for any
  * future calls for that object.
  *
  * @param Function func
  *        The generator function that to wrap as an async function.
  * @return Function
  *         The async function.
  */
 exports.asyncOnce = function asyncOnce(func) {
   const promises = new WeakMap();
   return function(...args) {
     let promise = promises.get(this);
     if (!promise) {
       promise = Task.spawn(func.apply(this, args));
       promises.set(this, promise);
     }
     return promise;
   };
 };
 /**
  * Call a function that expects a callback as the last argument and returns a
  * promise for the result. This simplifies using callback APIs from tasks and
  * async functions.
  *
  * @param Any obj
  *        The |this| value to call the function on.
  * @param Function func
  *        The callback-expecting function to call.
  * @param Array args
  *        Additional arguments to pass to the method.
  * @return Promise
  *         The promise for the result. If the callback is called with only one
  *         argument, it is used as the resolution value. If there's multiple
  *         arguments, an array containing the arguments is the resolution value.
  *         If the method throws, the promise is rejected with the thrown value.
  */
 function promisify(obj, func, args) {
   return new Promise(resolve => {
     args.push((...results) => {
       resolve(results.length > 1 ? results : results[0]);
     });
     func.apply(obj, args);
   });
 }
 /**
  * Call a method that expects a callback as the last argument and returns a
  * promise for the result.
  *
  * @see promisify
  */
 exports.promiseInvoke = function promiseInvoke(obj, func, ...args) {
   return promisify(obj, func, args);
 };
 /**
  * Call a function that expects a callback as the last argument.
  *
  * @see promisify
  */
 exports.promiseCall = function promiseCall(func, ...args) {
   return promisify(undefined, func, args);
 };