'use strict';
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function isPromise(obj) {
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return !!obj && (typeof obj === 'object' || typeof obj === 'function') && typeof obj.then === 'function';
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}
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/**
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* Return a function that will run a function asynchronously or synchronously
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*
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* example:
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* runAsync(wrappedFunction, callback)(...args);
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*
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* @param {Function} func Function to run
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* @param {Function} cb Callback function passed the `func` returned value
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* @return {Function(arguments)} Arguments to pass to `func`. This function will in turn
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* return a Promise (Node >= 0.12) or call the callbacks.
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*/
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var runAsync = module.exports = function (func, cb) {
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cb = cb || function () {};
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return function () {
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var args = arguments;
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var promise = new Promise(function (resolve, reject) {
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var resolved = false;
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const wrappedResolve = function (value) {
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if (resolved) {
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console.warn('Run-async promise already resolved.')
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}
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resolved = true;
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resolve(value);
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}
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var rejected = false;
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const wrappedReject = function (value) {
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if (rejected) {
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console.warn('Run-async promise already rejected.')
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}
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rejected = true;
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reject(value);
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}
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var usingCallback = false;
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var callbackConflict = false;
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var contextEnded = false;
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var answer = func.apply({
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async: function () {
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if (contextEnded) {
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console.warn('Run-async async() called outside a valid run-async context, callback will be ignored.');
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return function() {};
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}
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if (callbackConflict) {
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console.warn('Run-async wrapped function (async) returned a promise.\nCalls to async() callback can have unexpected results.');
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}
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usingCallback = true;
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return function (err, value) {
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if (err) {
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wrappedReject(err);
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} else {
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wrappedResolve(value);
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}
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};
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}
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}, Array.prototype.slice.call(args));
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if (usingCallback) {
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if (isPromise(answer)) {
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console.warn('Run-async wrapped function (sync) returned a promise but async() callback must be executed to resolve.');
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}
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} else {
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if (isPromise(answer)) {
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callbackConflict = true;
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answer.then(wrappedResolve, wrappedReject);
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} else {
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wrappedResolve(answer);
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}
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}
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contextEnded = true;
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});
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promise.then(cb.bind(null, null), cb);
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return promise;
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}
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};
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runAsync.cb = function (func, cb) {
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return runAsync(function () {
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var args = Array.prototype.slice.call(arguments);
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if (args.length === func.length - 1) {
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args.push(this.async());
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}
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return func.apply(this, args);
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}, cb);
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};
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