tenebrous-dicebot/api/node_modules/async/inject.js

78 lines
2.6 KiB
JavaScript

'use strict';
Object.defineProperty(exports, "__esModule", {
value: true
});
exports.default = reduce;
var _eachOfSeries = require('./eachOfSeries');
var _eachOfSeries2 = _interopRequireDefault(_eachOfSeries);
var _noop = require('lodash/noop');
var _noop2 = _interopRequireDefault(_noop);
var _once = require('./internal/once');
var _once2 = _interopRequireDefault(_once);
var _wrapAsync = require('./internal/wrapAsync');
var _wrapAsync2 = _interopRequireDefault(_wrapAsync);
function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
/**
* Reduces `coll` into a single value using an async `iteratee` to return each
* successive step. `memo` is the initial state of the reduction. This function
* only operates in series.
*
* For performance reasons, it may make sense to split a call to this function
* into a parallel map, and then use the normal `Array.prototype.reduce` on the
* results. This function is for situations where each step in the reduction
* needs to be async; if you can get the data before reducing it, then it's
* probably a good idea to do so.
*
* @name reduce
* @static
* @memberOf module:Collections
* @method
* @alias inject
* @alias foldl
* @category Collection
* @param {Array|Iterable|Object} coll - A collection to iterate over.
* @param {*} memo - The initial state of the reduction.
* @param {AsyncFunction} iteratee - A function applied to each item in the
* array to produce the next step in the reduction.
* The `iteratee` should complete with the next state of the reduction.
* If the iteratee complete with an error, the reduction is stopped and the
* main `callback` is immediately called with the error.
* Invoked with (memo, item, callback).
* @param {Function} [callback] - A callback which is called after all the
* `iteratee` functions have finished. Result is the reduced value. Invoked with
* (err, result).
* @example
*
* async.reduce([1,2,3], 0, function(memo, item, callback) {
* // pointless async:
* process.nextTick(function() {
* callback(null, memo + item)
* });
* }, function(err, result) {
* // result is now equal to the last value of memo, which is 6
* });
*/
function reduce(coll, memo, iteratee, callback) {
callback = (0, _once2.default)(callback || _noop2.default);
var _iteratee = (0, _wrapAsync2.default)(iteratee);
(0, _eachOfSeries2.default)(coll, function (x, i, callback) {
_iteratee(memo, x, function (err, v) {
memo = v;
callback(err);
});
}, function (err) {
callback(err, memo);
});
}
module.exports = exports['default'];