118 lines
3.7 KiB
JavaScript
118 lines
3.7 KiB
JavaScript
'use strict';
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Object.defineProperty(exports, "__esModule", {
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value: true
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});
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exports.default = asyncify;
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var _initialParams = require('./internal/initialParams.js');
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var _initialParams2 = _interopRequireDefault(_initialParams);
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var _setImmediate = require('./internal/setImmediate.js');
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var _setImmediate2 = _interopRequireDefault(_setImmediate);
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var _wrapAsync = require('./internal/wrapAsync.js');
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function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
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/**
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* Take a sync function and make it async, passing its return value to a
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* callback. This is useful for plugging sync functions into a waterfall,
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* series, or other async functions. Any arguments passed to the generated
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* function will be passed to the wrapped function (except for the final
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* callback argument). Errors thrown will be passed to the callback.
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*
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* If the function passed to `asyncify` returns a Promise, that promises's
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* resolved/rejected state will be used to call the callback, rather than simply
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* the synchronous return value.
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*
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* This also means you can asyncify ES2017 `async` functions.
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*
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* @name asyncify
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* @static
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* @memberOf module:Utils
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* @method
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* @alias wrapSync
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* @category Util
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* @param {Function} func - The synchronous function, or Promise-returning
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* function to convert to an {@link AsyncFunction}.
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* @returns {AsyncFunction} An asynchronous wrapper of the `func`. To be
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* invoked with `(args..., callback)`.
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* @example
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*
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* // passing a regular synchronous function
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* async.waterfall([
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* async.apply(fs.readFile, filename, "utf8"),
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* async.asyncify(JSON.parse),
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* function (data, next) {
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* // data is the result of parsing the text.
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* // If there was a parsing error, it would have been caught.
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* }
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* ], callback);
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*
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* // passing a function returning a promise
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* async.waterfall([
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* async.apply(fs.readFile, filename, "utf8"),
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* async.asyncify(function (contents) {
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* return db.model.create(contents);
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* }),
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* function (model, next) {
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* // `model` is the instantiated model object.
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* // If there was an error, this function would be skipped.
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* }
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* ], callback);
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*
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* // es2017 example, though `asyncify` is not needed if your JS environment
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* // supports async functions out of the box
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* var q = async.queue(async.asyncify(async function(file) {
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* var intermediateStep = await processFile(file);
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* return await somePromise(intermediateStep)
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* }));
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*
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* q.push(files);
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*/
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function asyncify(func) {
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if ((0, _wrapAsync.isAsync)(func)) {
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return function (...args /*, callback*/) {
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const callback = args.pop();
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const promise = func.apply(this, args);
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return handlePromise(promise, callback);
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};
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}
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return (0, _initialParams2.default)(function (args, callback) {
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var result;
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try {
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result = func.apply(this, args);
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} catch (e) {
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return callback(e);
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}
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// if result is Promise object
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if (result && typeof result.then === 'function') {
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return handlePromise(result, callback);
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} else {
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callback(null, result);
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}
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});
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}
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function handlePromise(promise, callback) {
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return promise.then(value => {
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invokeCallback(callback, null, value);
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}, err => {
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invokeCallback(callback, err && (err instanceof Error || err.message) ? err : new Error(err));
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});
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}
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function invokeCallback(callback, error, value) {
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try {
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callback(error, value);
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} catch (err) {
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(0, _setImmediate2.default)(e => {
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throw e;
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}, err);
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}
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}
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module.exports = exports.default; |