1'use strict';
2
3Object.defineProperty(exports, "__esModule", {
4    value: true
5});
6exports.default = ensureAsync;
7
8var _setImmediate = require('./internal/setImmediate.js');
9
10var _setImmediate2 = _interopRequireDefault(_setImmediate);
11
12var _wrapAsync = require('./internal/wrapAsync.js');
13
14function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
15
16/**
17 * Wrap an async function and ensure it calls its callback on a later tick of
18 * the event loop.  If the function already calls its callback on a next tick,
19 * no extra deferral is added. This is useful for preventing stack overflows
20 * (`RangeError: Maximum call stack size exceeded`) and generally keeping
21 * [Zalgo](http://blog.izs.me/post/59142742143/designing-apis-for-asynchrony)
22 * contained. ES2017 `async` functions are returned as-is -- they are immune
23 * to Zalgo's corrupting influences, as they always resolve on a later tick.
24 *
25 * @name ensureAsync
26 * @static
27 * @memberOf module:Utils
28 * @method
29 * @category Util
30 * @param {AsyncFunction} fn - an async function, one that expects a node-style
31 * callback as its last argument.
32 * @returns {AsyncFunction} Returns a wrapped function with the exact same call
33 * signature as the function passed in.
34 * @example
35 *
36 * function sometimesAsync(arg, callback) {
37 *     if (cache[arg]) {
38 *         return callback(null, cache[arg]); // this would be synchronous!!
39 *     } else {
40 *         doSomeIO(arg, callback); // this IO would be asynchronous
41 *     }
42 * }
43 *
44 * // this has a risk of stack overflows if many results are cached in a row
45 * async.mapSeries(args, sometimesAsync, done);
46 *
47 * // this will defer sometimesAsync's callback if necessary,
48 * // preventing stack overflows
49 * async.mapSeries(args, async.ensureAsync(sometimesAsync), done);
50 */
51function ensureAsync(fn) {
52    if ((0, _wrapAsync.isAsync)(fn)) return fn;
53    return function (...args /*, callback*/) {
54        var callback = args.pop();
55        var sync = true;
56        args.push((...innerArgs) => {
57            if (sync) {
58                (0, _setImmediate2.default)(() => callback(...innerArgs));
59            } else {
60                callback(...innerArgs);
61            }
62        });
63        fn.apply(this, args);
64        sync = false;
65    };
66}
67module.exports = exports['default'];