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Diffstat (limited to 'node_modules/co/index.js')
-rw-r--r-- | node_modules/co/index.js | 237 |
1 files changed, 237 insertions, 0 deletions
diff --git a/node_modules/co/index.js b/node_modules/co/index.js new file mode 100644 index 0000000..87ba8ba --- /dev/null +++ b/node_modules/co/index.js @@ -0,0 +1,237 @@ + +/** + * 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 Promise(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 Promise(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 Promise.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; +} |