source: trip-planner-front/node_modules/async/foldl.js@ 188ee53

Last change on this file since 188ee53 was 6a3a178, checked in by Ema <ema_spirova@…>, 3 years ago

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1'use strict';
2
3Object.defineProperty(exports, "__esModule", {
4 value: true
5});
6exports.default = reduce;
7
8var _eachOfSeries = require('./eachOfSeries');
9
10var _eachOfSeries2 = _interopRequireDefault(_eachOfSeries);
11
12var _noop = require('lodash/noop');
13
14var _noop2 = _interopRequireDefault(_noop);
15
16var _once = require('./internal/once');
17
18var _once2 = _interopRequireDefault(_once);
19
20var _wrapAsync = require('./internal/wrapAsync');
21
22var _wrapAsync2 = _interopRequireDefault(_wrapAsync);
23
24function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
25
26/**
27 * Reduces `coll` into a single value using an async `iteratee` to return each
28 * successive step. `memo` is the initial state of the reduction. This function
29 * only operates in series.
30 *
31 * For performance reasons, it may make sense to split a call to this function
32 * into a parallel map, and then use the normal `Array.prototype.reduce` on the
33 * results. This function is for situations where each step in the reduction
34 * needs to be async; if you can get the data before reducing it, then it's
35 * probably a good idea to do so.
36 *
37 * @name reduce
38 * @static
39 * @memberOf module:Collections
40 * @method
41 * @alias inject
42 * @alias foldl
43 * @category Collection
44 * @param {Array|Iterable|Object} coll - A collection to iterate over.
45 * @param {*} memo - The initial state of the reduction.
46 * @param {AsyncFunction} iteratee - A function applied to each item in the
47 * array to produce the next step in the reduction.
48 * The `iteratee` should complete with the next state of the reduction.
49 * If the iteratee complete with an error, the reduction is stopped and the
50 * main `callback` is immediately called with the error.
51 * Invoked with (memo, item, callback).
52 * @param {Function} [callback] - A callback which is called after all the
53 * `iteratee` functions have finished. Result is the reduced value. Invoked with
54 * (err, result).
55 * @example
56 *
57 * async.reduce([1,2,3], 0, function(memo, item, callback) {
58 * // pointless async:
59 * process.nextTick(function() {
60 * callback(null, memo + item)
61 * });
62 * }, function(err, result) {
63 * // result is now equal to the last value of memo, which is 6
64 * });
65 */
66function reduce(coll, memo, iteratee, callback) {
67 callback = (0, _once2.default)(callback || _noop2.default);
68 var _iteratee = (0, _wrapAsync2.default)(iteratee);
69 (0, _eachOfSeries2.default)(coll, function (x, i, callback) {
70 _iteratee(memo, x, function (err, v) {
71 memo = v;
72 callback(err);
73 });
74 }, function (err) {
75 callback(err, memo);
76 });
77}
78module.exports = exports['default'];
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