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Direktori : /lib/node_modules/pm2/node_modules/async/ |
Current File : //lib/node_modules/pm2/node_modules/async/reduce.js |
'use strict'; Object.defineProperty(exports, "__esModule", { value: true }); var _eachOfSeries = require('./eachOfSeries.js'); var _eachOfSeries2 = _interopRequireDefault(_eachOfSeries); var _once = require('./internal/once.js'); var _once2 = _interopRequireDefault(_once); var _wrapAsync = require('./internal/wrapAsync.js'); var _wrapAsync2 = _interopRequireDefault(_wrapAsync); var _awaitify = require('./internal/awaitify.js'); var _awaitify2 = _interopRequireDefault(_awaitify); 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|AsyncIterable|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 completes 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). * @returns {Promise} a promise, if no callback is passed * @example * * // file1.txt is a file that is 1000 bytes in size * // file2.txt is a file that is 2000 bytes in size * // file3.txt is a file that is 3000 bytes in size * // file4.txt does not exist * * const fileList = ['file1.txt','file2.txt','file3.txt']; * const withMissingFileList = ['file1.txt','file2.txt','file3.txt', 'file4.txt']; * * // asynchronous function that computes the file size in bytes * // file size is added to the memoized value, then returned * function getFileSizeInBytes(memo, file, callback) { * fs.stat(file, function(err, stat) { * if (err) { * return callback(err); * } * callback(null, memo + stat.size); * }); * } * * // Using callbacks * async.reduce(fileList, 0, getFileSizeInBytes, function(err, result) { * if (err) { * console.log(err); * } else { * console.log(result); * // 6000 * // which is the sum of the file sizes of the three files * } * }); * * // Error Handling * async.reduce(withMissingFileList, 0, getFileSizeInBytes, function(err, result) { * if (err) { * console.log(err); * // [ Error: ENOENT: no such file or directory ] * } else { * console.log(result); * } * }); * * // Using Promises * async.reduce(fileList, 0, getFileSizeInBytes) * .then( result => { * console.log(result); * // 6000 * // which is the sum of the file sizes of the three files * }).catch( err => { * console.log(err); * }); * * // Error Handling * async.reduce(withMissingFileList, 0, getFileSizeInBytes) * .then( result => { * console.log(result); * }).catch( err => { * console.log(err); * // [ Error: ENOENT: no such file or directory ] * }); * * // Using async/await * async () => { * try { * let result = await async.reduce(fileList, 0, getFileSizeInBytes); * console.log(result); * // 6000 * // which is the sum of the file sizes of the three files * } * catch (err) { * console.log(err); * } * } * * // Error Handling * async () => { * try { * let result = await async.reduce(withMissingFileList, 0, getFileSizeInBytes); * console.log(result); * } * catch (err) { * console.log(err); * // [ Error: ENOENT: no such file or directory ] * } * } * */ function reduce(coll, memo, iteratee, callback) { callback = (0, _once2.default)(callback); var _iteratee = (0, _wrapAsync2.default)(iteratee); return (0, _eachOfSeries2.default)(coll, (x, i, iterCb) => { _iteratee(memo, x, (err, v) => { memo = v; iterCb(err); }); }, err => callback(err, memo)); } exports.default = (0, _awaitify2.default)(reduce, 4); module.exports = exports['default'];