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

87 lines
2.7 KiB
JavaScript

'use strict';
Object.defineProperty(exports, "__esModule", {
value: true
});
exports.default = transform;
var _isArray = require('lodash/isArray');
var _isArray2 = _interopRequireDefault(_isArray);
var _noop = require('lodash/noop');
var _noop2 = _interopRequireDefault(_noop);
var _eachOf = require('./eachOf');
var _eachOf2 = _interopRequireDefault(_eachOf);
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 }; }
/**
* A relative of `reduce`. Takes an Object or Array, and iterates over each
* element in series, each step potentially mutating an `accumulator` value.
* The type of the accumulator defaults to the type of collection passed in.
*
* @name transform
* @static
* @memberOf module:Collections
* @method
* @category Collection
* @param {Array|Iterable|Object} coll - A collection to iterate over.
* @param {*} [accumulator] - The initial state of the transform. If omitted,
* it will default to an empty Object or Array, depending on the type of `coll`
* @param {AsyncFunction} iteratee - A function applied to each item in the
* collection that potentially modifies the accumulator.
* Invoked with (accumulator, item, key, callback).
* @param {Function} [callback] - A callback which is called after all the
* `iteratee` functions have finished. Result is the transformed accumulator.
* Invoked with (err, result).
* @example
*
* async.transform([1,2,3], function(acc, item, index, callback) {
* // pointless async:
* process.nextTick(function() {
* acc.push(item * 2)
* callback(null)
* });
* }, function(err, result) {
* // result is now equal to [2, 4, 6]
* });
*
* @example
*
* async.transform({a: 1, b: 2, c: 3}, function (obj, val, key, callback) {
* setImmediate(function () {
* obj[key] = val * 2;
* callback();
* })
* }, function (err, result) {
* // result is equal to {a: 2, b: 4, c: 6}
* })
*/
function transform(coll, accumulator, iteratee, callback) {
if (arguments.length <= 3) {
callback = iteratee;
iteratee = accumulator;
accumulator = (0, _isArray2.default)(coll) ? [] : {};
}
callback = (0, _once2.default)(callback || _noop2.default);
var _iteratee = (0, _wrapAsync2.default)(iteratee);
(0, _eachOf2.default)(coll, function (v, k, cb) {
_iteratee(accumulator, v, k, cb);
}, function (err) {
callback(err, accumulator);
});
}
module.exports = exports['default'];