1  'use strict';
 2  
 3  Object.defineProperty(exports, "__esModule", {
 4      value: true
 5  });
 6  exports.default = seq;
 7  
 8  var _reduce = require('./reduce');
 9  
10  var _reduce2 = _interopRequireDefault(_reduce);
11  
12  var _wrapAsync = require('./internal/wrapAsync');
13  
14  var _wrapAsync2 = _interopRequireDefault(_wrapAsync);
15  
16  var _promiseCallback = require('./internal/promiseCallback');
17  
18  function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
19  
20  /**
21   * Version of the compose function that is more natural to read. Each function
22   * consumes the return value of the previous function. It is the equivalent of
23   * [compose]{@link module:ControlFlow.compose} with the arguments reversed.
24   *
25   * Each function is executed with the `this` binding of the composed function.
26   *
27   * @name seq
28   * @static
29   * @memberOf module:ControlFlow
30   * @method
31   * @see [async.compose]{@link module:ControlFlow.compose}
32   * @category Control Flow
33   * @param {...AsyncFunction} functions - the asynchronous functions to compose
34   * @returns {Function} a function that composes the `functions` in order
35   * @example
36   *
37   * // Requires lodash (or underscore), express3 and dresende's orm2.
38   * // Part of an app, that fetches cats of the logged user.
39   * // This example uses `seq` function to avoid overnesting and error
40   * // handling clutter.
41   * app.get('/cats', function(request, response) {
42   *     var User = request.models.User;
43   *     async.seq(
44   *         _.bind(User.get, User),  // 'User.get' has signature (id, callback(err, data))
45   *         function(user, fn) {
46   *             user.getCats(fn);      // 'getCats' has signature (callback(err, data))
47   *         }
48   *     )(req.session.user_id, function (err, cats) {
49   *         if (err) {
50   *             console.error(err);
51   *             response.json({ status: 'error', message: err.message });
52   *         } else {
53   *             response.json({ status: 'ok', message: 'Cats found', data: cats });
54   *         }
55   *     });
56   * });
57   */
58  function seq(...functions) {
59      var _functions = functions.map(_wrapAsync2.default);
60      return function (...args) {
61          var that = this;
62  
63          var cb = args[args.length - 1];
64          if (typeof cb == 'function') {
65              args.pop();
66          } else {
67              cb = (0, _promiseCallback.promiseCallback)();
68          }
69  
70          (0, _reduce2.default)(_functions, args, (newargs, fn, iterCb) => {
71              fn.apply(that, newargs.concat((err, ...nextargs) => {
72                  iterCb(err, nextargs);
73              }));
74          }, (err, results) => cb(err, ...results));
75  
76          return cb[_promiseCallback.PROMISE_SYMBOL];
77      };
78  }
79  module.exports = exports['default'];