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Diffstat (limited to 'node_modules/async/wrapSync.js')
-rw-r--r-- | node_modules/async/wrapSync.js | 118 |
1 files changed, 118 insertions, 0 deletions
diff --git a/node_modules/async/wrapSync.js b/node_modules/async/wrapSync.js new file mode 100644 index 0000000..3c3bf88 --- /dev/null +++ b/node_modules/async/wrapSync.js @@ -0,0 +1,118 @@ +'use strict'; + +Object.defineProperty(exports, "__esModule", { + value: true +}); +exports.default = asyncify; + +var _initialParams = require('./internal/initialParams.js'); + +var _initialParams2 = _interopRequireDefault(_initialParams); + +var _setImmediate = require('./internal/setImmediate.js'); + +var _setImmediate2 = _interopRequireDefault(_setImmediate); + +var _wrapAsync = require('./internal/wrapAsync.js'); + +function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; } + +/** + * Take a sync function and make it async, passing its return value to a + * callback. This is useful for plugging sync functions into a waterfall, + * series, or other async functions. Any arguments passed to the generated + * function will be passed to the wrapped function (except for the final + * callback argument). Errors thrown will be passed to the callback. + * + * If the function passed to `asyncify` returns a Promise, that promises's + * resolved/rejected state will be used to call the callback, rather than simply + * the synchronous return value. + * + * This also means you can asyncify ES2017 `async` functions. + * + * @name asyncify + * @static + * @memberOf module:Utils + * @method + * @alias wrapSync + * @category Util + * @param {Function} func - The synchronous function, or Promise-returning + * function to convert to an {@link AsyncFunction}. + * @returns {AsyncFunction} An asynchronous wrapper of the `func`. To be + * invoked with `(args..., callback)`. + * @example + * + * // passing a regular synchronous function + * async.waterfall([ + * async.apply(fs.readFile, filename, "utf8"), + * async.asyncify(JSON.parse), + * function (data, next) { + * // data is the result of parsing the text. + * // If there was a parsing error, it would have been caught. + * } + * ], callback); + * + * // passing a function returning a promise + * async.waterfall([ + * async.apply(fs.readFile, filename, "utf8"), + * async.asyncify(function (contents) { + * return db.model.create(contents); + * }), + * function (model, next) { + * // `model` is the instantiated model object. + * // If there was an error, this function would be skipped. + * } + * ], callback); + * + * // es2017 example, though `asyncify` is not needed if your JS environment + * // supports async functions out of the box + * var q = async.queue(async.asyncify(async function(file) { + * var intermediateStep = await processFile(file); + * return await somePromise(intermediateStep) + * })); + * + * q.push(files); + */ +function asyncify(func) { + if ((0, _wrapAsync.isAsync)(func)) { + return function (...args /*, callback*/) { + const callback = args.pop(); + const promise = func.apply(this, args); + return handlePromise(promise, callback); + }; + } + + return (0, _initialParams2.default)(function (args, callback) { + var result; + try { + result = func.apply(this, args); + } catch (e) { + return callback(e); + } + // if result is Promise object + if (result && typeof result.then === 'function') { + return handlePromise(result, callback); + } else { + callback(null, result); + } + }); +} + +function handlePromise(promise, callback) { + return promise.then(value => { + invokeCallback(callback, null, value); + }, err => { + invokeCallback(callback, err && err.message ? err : new Error(err)); + }); +} + +function invokeCallback(callback, error, value) { + try { + callback(error, value); + } catch (err) { + (0, _setImmediate2.default)(e => { + throw e; + }, err); + } +} +module.exports = exports['default'];
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