var PinkiePromise = require('pinkie-promise'); /** * slice() reference. */ var slice = Array.prototype.slice; /** * Expose `co`. */ module.exports = co['default'] = co.co = co; /** * Wrap the given generator `fn` into a * function that returns a promise. * This is a separate function so that * every `co()` call doesn't create a new, * unnecessary closure. * * @param {GeneratorFunction} fn * @return {Function} * @api public */ co.wrap = function (fn) { createPromise.__generatorFunction__ = fn; return createPromise; function createPromise() { return co.call(this, fn.apply(this, arguments)); } }; /** * Execute the generator function or a generator * and return a promise. * * @param {Function} fn * @return {Promise} * @api public */ function co(gen) { var ctx = this; var args = slice.call(arguments, 1) // we wrap everything in a promise to avoid promise chaining, // which leads to memory leak errors. // see https://github.com/tj/co/issues/180 return new PinkiePromise(function(resolve, reject) { if (typeof gen === 'function') gen = gen.apply(ctx, args); if (!gen || typeof gen.next !== 'function') return resolve(gen); onFulfilled(); /** * @param {Mixed} res * @return {Promise} * @api private */ function onFulfilled(res) { var ret; try { ret = gen.next(res); } catch (e) { return reject(e); } next(ret); } /** * @param {Error} err * @return {Promise} * @api private */ function onRejected(err) { var ret; try { ret = gen.throw(err); } catch (e) { return reject(e); } next(ret); } /** * Get the next value in the generator, * return a promise. * * @param {Object} ret * @return {Promise} * @api private */ function next(ret) { if (ret.done) return resolve(ret.value); var value = toPromise.call(ctx, ret.value); if (value && isPromise(value)) return value.then(onFulfilled, onRejected); return onRejected(new TypeError('You may only yield a function, promise, generator, array, or object, ' + 'but the following object was passed: "' + String(ret.value) + '"')); } }); } /** * Convert a `yield`ed value into a promise. * * @param {Mixed} obj * @return {Promise} * @api private */ function toPromise(obj) { if (!obj) return obj; if (isPromise(obj)) return obj; if (isGeneratorFunction(obj) || isGenerator(obj)) return co.call(this, obj); if ('function' == typeof obj) return thunkToPromise.call(this, obj); if (Array.isArray(obj)) return arrayToPromise.call(this, obj); if (isObject(obj)) return objectToPromise.call(this, obj); return obj; } /** * Convert a thunk to a promise. * * @param {Function} * @return {Promise} * @api private */ function thunkToPromise(fn) { var ctx = this; return new PinkiePromise(function (resolve, reject) { fn.call(ctx, function (err, res) { if (err) return reject(err); if (arguments.length > 2) res = slice.call(arguments, 1); resolve(res); }); }); } /** * Convert an array of "yieldables" to a promise. * Uses `Promise.all()` internally. * * @param {Array} obj * @return {Promise} * @api private */ function arrayToPromise(obj) { return Promise.all(obj.map(toPromise, this)); } /** * Convert an object of "yieldables" to a promise. * Uses `Promise.all()` internally. * * @param {Object} obj * @return {Promise} * @api private */ function objectToPromise(obj){ var results = new obj.constructor(); var keys = Object.keys(obj); var promises = []; for (var i = 0; i < keys.length; i++) { var key = keys[i]; var promise = toPromise.call(this, obj[key]); if (promise && isPromise(promise)) defer(promise, key); else results[key] = obj[key]; } return PinkiePromise.all(promises).then(function () { return results; }); function defer(promise, key) { // predefine the key in the result results[key] = undefined; promises.push(promise.then(function (res) { results[key] = res; })); } } /** * Check if `obj` is a promise. * * @param {Object} obj * @return {Boolean} * @api private */ function isPromise(obj) { return 'function' == typeof obj.then; } /** * Check if `obj` is a generator. * * @param {Mixed} obj * @return {Boolean} * @api private */ function isGenerator(obj) { return 'function' == typeof obj.next && 'function' == typeof obj.throw; } /** * Check if `obj` is a generator function. * * @param {Mixed} obj * @return {Boolean} * @api private */ function isGeneratorFunction(obj) { var constructor = obj.constructor; if (!constructor) return false; if ('GeneratorFunction' === constructor.name || 'GeneratorFunction' === constructor.displayName) return true; return isGenerator(constructor.prototype); } /** * Check for plain object. * * @param {Mixed} val * @return {Boolean} * @api private */ function isObject(val) { return Object == val.constructor; }