GT2/Ejectable/node_modules/run-async/index.js

99 lines
2.8 KiB
JavaScript

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