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promises: A+ compliance, better async, unhandled rejection reporter

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This commit is contained in:
Leo Horie 2016-06-01 01:24:14 -04:00
parent 3bb0a6287f
commit 2e6e1c73d0
2 changed files with 45 additions and 23 deletions
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48
promise/promise.js
View file

@ -5,25 +5,23 @@ function Promise(executor) {
if (typeof executor !== "function") throw new Error("executor must be a function") if (typeof executor !== "function") throw new Error("executor must be a function")
var self = this, resolvers = [], rejectors = [], resolveCurrent = handler(resolvers, true), rejectCurrent = handler(rejectors, false) var self = this, resolvers = [], rejectors = [], resolveCurrent = handler(resolvers, true), rejectCurrent = handler(rejectors, false)
var instance = self._instance = {resolvers: resolvers, rejectors: rejectors}
var callAsync = typeof setImmediate === "function" ? setImmediate : setTimeout
function handler(list, shouldAbsorb) { function handler(list, shouldAbsorb) {
var done = false
return function execute(value) { return function execute(value) {
if (done) return
done = true
var then var then
try { try {
if (shouldAbsorb && value != null && (typeof value === "object" || typeof value === "function") && typeof (then = value.then) === "function") { if (shouldAbsorb && value != null && (typeof value === "object" || typeof value === "function") && typeof (then = value.then) === "function") {
if (value === self) rejectCurrent(new TypeError("Promise can't be resolved w/ itself")) if (value === self) throw new TypeError("Promise can't be resolved w/ itself")
then.call(value, handler(list, shouldAbsorb), rejectCurrent) executeOnce(then.bind(value))
} }
else { else {
setTimeout(function() { callAsync(function() {
if (!shouldAbsorb && list.length === 0) console.error("Possible unhandled promise rejection:", value)
for (var i = 0; i < list.length; i++) list[i](value) for (var i = 0; i < list.length; i++) list[i](value)
instance.retry = function() { resolvers.length = 0, rejectors.length = 0
done = false instance.state = shouldAbsorb
execute(value) instance.retry = function() {execute(value)}
}
}, 0) }, 0)
} }
} }
@ -32,23 +30,32 @@ function Promise(executor) {
} }
} }
} }
var instance = this._instance = {resolvers: resolvers, rejectors: rejectors} function executeOnce(then) {
var runs = 0
function run(fn) {
return function(value) {
if (runs++ > 0) return
fn(value)
}
}
var onerror = run(rejectCurrent)
try {then(run(resolveCurrent), onerror)} catch (e) {onerror(e)}
}
try {executor(resolveCurrent, rejectCurrent)} catch (e) {rejectCurrent(e)} executeOnce(executor)
} }
Promise.prototype.then = function(onFulfilled, onRejection) { Promise.prototype.then = function(onFulfilled, onRejection) {
var self = this var self = this, instance = self._instance
function handle(callback, list, next, state) { function handle(callback, list, next, state) {
list.push(function(value) { list.push(function(value) {
if (typeof callback !== "function") next(value) if (typeof callback !== "function") next(value)
try {resolveNext(callback(value))} catch (e) {if (rejectNext) rejectNext(e)} else try {resolveNext(callback(value))} catch (e) {if (rejectNext) rejectNext(e)}
}) })
var retry = self._instance.retry if (typeof instance.retry === "function" && state === instance.state) instance.retry()
if (retry) retry()
} }
var resolveNext, rejectNext var resolveNext, rejectNext
var promise = new Promise(function(resolve, reject) {resolveNext = resolve, rejectNext = reject}) var promise = new Promise(function(resolve, reject) {resolveNext = resolve, rejectNext = reject})
handle(onFulfilled, this._instance.resolvers, resolveNext, true), handle(onRejection, this._instance.rejectors, rejectNext, false) handle(onFulfilled, instance.resolvers, resolveNext, true), handle(onRejection, instance.rejectors, rejectNext, false)
return promise return promise
} }
Promise.prototype.catch = function(onRejection) { Promise.prototype.catch = function(onRejection) {
@ -71,9 +78,8 @@ Promise.all = function(list) {
values[i] = value values[i] = value
if (count === total) resolve(values) if (count === total) resolve(values)
} }
var then if (list[i] != null && (typeof list[i] === "object" || typeof list[i] === "function") && typeof list[i].then === "function") {
if (list[i] != null && (typeof list[i] === "object" || typeof list[i] === "function") && typeof (then = list[i].then) === "function") { list[i].then(consume, reject)
then.call(list[i], consume, reject)
} }
else consume(list[i]) else consume(list[i])
}(i) }(i)

20
promise/tests/test-promise.js
View file

@ -282,7 +282,8 @@ o.spec("promise", function() {
}) })
o("absorbs resolved promise in executor resolve", function(done) { o("absorbs resolved promise in executor resolve", function(done) {
var promise = new Promise(function(resolve, reject) { var promise = new Promise(function(resolve, reject) {
resolve(Promise.resolve(1)) var p = Promise.resolve(1)
resolve(p)
}) })
promise.then(function(value) { promise.then(function(value) {
@ -482,7 +483,7 @@ o.spec("promise", function() {
done() done()
}, 10) }, 10)
}) })
o("absorbs early resolved promise", function(done, t) { o("absorbs early resolved promise", function(done) {
var resolved = Promise.resolve(1) var resolved = Promise.resolve(1)
var promise = new Promise(function(resolve) { var promise = new Promise(function(resolve) {
setTimeout(function() { setTimeout(function() {
@ -589,5 +590,20 @@ o.spec("promise", function() {
done() done()
}) })
}) })
o("works if thennable resolves async rejection then throws", function(done) {
var promise = new Promise(function(res) {
res({
then: function(resolve, reject) {
setTimeout(function() {reject(2)})
}
})
throw 3
})
promise.then(null, function(value) {
o(value).equals(2)
done()
})
})
}) })
}) })