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promise polyfill

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This commit is contained in:
Leo Horie 2016-05-26 15:23:06 -04:00
parent 41ac2bf002
commit 76d5d9ef2f
3 changed files with 589 additions and 0 deletions
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74
promise/promise.js Normal file
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"use strict"
function Promise(executor) {
if (!(this instanceof Promise)) throw new Error("Promise must be called with `new`")
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)
function handler(list, shouldAbsorb) {
return function execute(value) {
if (shouldAbsorb && (typeof value === "object" || typeof value === "function") && typeof value.then === "function") {
if (value === self) rejectCurrent(new Error("Promise cannot be resolved with itself"))
value.then(execute, rejectCurrent)
}
else {
setTimeout(function() {
for (var i = 0; i < list.length; i++) list[i](value)
resolvers.length = 0, rejectors.length = 0
}, 0)
}
}
}
this._instance = {resolvers: resolvers, rejectors: rejectors}
try {executor(resolveCurrent, rejectCurrent)} catch (e) {rejectCurrent(e)}
}
Promise.prototype.then = function(onFulfilled, onRejection) {
function handle(callback, list) {
if (typeof callback === "function") {
list.push(function(value) {
try {resolveNext(callback(value))} catch (e) {if (rejectNext) rejectNext(e)}
})
}
}
var resolveNext, rejectNext
handle(onFulfilled, this._instance.resolvers), handle(onRejection, this._instance.rejectors)
return new Promise(function(resolve, reject) {resolveNext = resolve, rejectNext = reject})
}
Promise.prototype.catch = function(onRejection) {
return this.then(null, onRejection)
}
Promise.resolve = function(value) {
if (value instanceof Promise) return value
return new Promise(function(resolve, reject) {resolve(value)})
}
Promise.reject = function(value) {
return new Promise(function(resolve, reject) {reject(value)})
}
Promise.all = function(list) {
return new Promise(function(resolve, reject) {
var total = list.length, count = 0, values = []
for (var i = 0; i < list.length; i++) {
new function(i) {
function consume(value) {
count++
values[i] = value
if (count === total) resolve(values)
}
if ((typeof list[i] === "object" || typeof list[i] === "function") && typeof list[i].then === "function") {
list[i].then(consume, reject)
}
else consume(list[i])
}(i)
}
})
}
Promise.race = function(list) {
return new Promise(function(resolve, reject) {
for (var i = 0; i < list.length; i++) {
list[i].then(resolve, reject)
}
})
}
module.exports = Promise

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promise/tests/index.html Normal file
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<!doctype html>
<html>
<head>
<meta charset="utf-8">
</head>
<body>
<script src="../../module/module.js"></script>
<script src="../../ospec/ospec.js"></script>
<script src="../../test-utils/callAsync.js"></script>
<script src="../../promise/promise.js"></script>
<script src="test-promise.js"></script>
<script>require("../../ospec/ospec").run()</script>
</body>
</html>

499
promise/tests/test-promise.js Normal file
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"use strict"
var o = require("../../ospec/ospec")
var callAsync = require("../../test-utils/callAsync")
var Promise = require("../../promise/promise")
o.spec("promise", function() {
o.spec("constructor", function() {
o("constructor throws if called without new", function(done) {
try {Promise(function() {})} catch(e) {done()}
})
o("constructor throws if called without executor", function(done) {
try {new Promise()} catch(e) {done()}
})
o("constructor has correct methods", function() {
o(typeof Promise.prototype.then).equals("function")
o(typeof Promise.prototype.catch).equals("function")
o(typeof Promise.resolve).equals("function")
o(typeof Promise.reject).equals("function")
o(typeof Promise.race).equals("function")
o(typeof Promise.all).equals("function")
})
})
o.spec("return value", function() {
o("static resolve returns promise", function() {
var promise = Promise.resolve()
o(promise instanceof Promise).equals(true)
})
o("static resolve returns promise", function() {
var promise = Promise.reject()
promise.catch(function() {})
o(promise instanceof Promise).equals(true)
})
o("static resolve with promise input returns same promise", function() {
var resolved = Promise.resolve(1)
var promise = Promise.resolve(resolved)
o(promise).equals(resolved)
})
o("then returns promise", function(done) {
var promise = Promise.resolve(1)
promise.then(function(value) {
o(value).equals(1)
}).then(done)
})
o("catch returns promise", function(done) {
var promise = Promise.reject(1)
promise.catch(function(value) {
o(value).equals(1)
}).then(done)
})
})
o.spec("resolve", function() {
o("resolves once", function(done) {
var callCount = 0
var promise = new Promise(function(resolve, reject) {
resolve(1)
resolve(2)
callAsync(function() {resolve(3)})
})
promise.then(function(value) {
callCount++
o(value).equals(1)
o(callCount).equals(1)
done()
})
})
o("does not reject after resolve", function(done) {
var promise = new Promise(function(resolve, reject) {
resolve(1)
reject(2)
callAsync(function() {reject(3)})
})
promise.then(function(value) {
o(value).equals(1)
done()
})
})
o("resolves asynchronously", function(done) {
var state = 0
var promise = Promise.resolve()
state = 1
promise.then(function(value) {
o(state).equals(2)
done()
})
state = 2
})
o("resolves via static method", function(done) {
var promise = Promise.resolve(1)
promise.then(function(value) {
o(value).equals(1)
done()
})
})
o("resolves asynchronously via executor", function(done) {
var promise = new Promise(function(resolve, reject) {
callAsync(function() {resolve(1)})
})
promise.then(function(value) {
o(value).equals(1)
done()
})
})
o("downstreams correctly", function(done) {
var promise = Promise.resolve(1)
var a = promise.then(function(value) {return value + 1})
var b = promise.then(function(value) {return value + 2})
a.then(function(aValue) {
b.then(function(bValue) {
o(aValue).equals(2)
o(bValue).equals(3)
done()
})
})
})
o("cannot resolve to itself", function(done) {
var promise = new Promise(function(resolve) {
callAsync(function() {resolve(promise)})
})
promise.then(null, done)
})
})
o.spec("reject", function() {
o("rejects once", function(done) {
var callCount = 0
var promise = new Promise(function(resolve, reject) {
reject(1)
reject(2)
callAsync(function() {reject(3)})
})
promise.then(null, function(value) {
callCount++
o(value).equals(1)
o(callCount).equals(1)
done()
})
})
o("does not resolve after reject", function(done) {
var promise = new Promise(function(resolve, reject) {
reject(1)
resolve(2)
callAsync(function() {resolve(3)})
})
promise.then(null, function(value) {
o(value).equals(1)
done()
})
})
o("rejects asynchronously", function(done) {
var state = 0
var promise = Promise.reject()
state = 1
promise.then(null, function(value) {
o(state).equals(2)
done()
})
state = 2
})
o("does not catch itself", function(done) {
var callCount = 0
var promise = Promise.resolve().then(function() {throw 1}, function() {callCount++})
promise.then(null, function() {
o(callCount).equals(0)
done()
})
})
o("rejects via static method", function(done) {
var promise = Promise.reject(1)
promise.then(null, function(value) {
o(value).equals(1)
return value
}).then(function(value) {
o(value).equals(1)
done()
})
})
o("rejects synchronously via executor", function(done) {
var promise = new Promise(function(resolve, reject) {
reject(1)
})
promise.then(null, function(value) {
o(value).equals(1)
done()
})
})
o("rejects asynchronously via executor", function(done) {
var promise = new Promise(function(resolve, reject) {
callAsync(function() {reject(1)})
})
promise.then(null, function(value) {
o(value).equals(1)
done()
})
})
o("rejects via executor on error", function(done) {
var promise = new Promise(function(resolve, reject) {
throw 1
})
promise.then(null, function(value) {
o(value).equals(1)
done()
})
})
o("rejects on fulfillment error", function(done) {
var promise = Promise.resolve()
promise.then(function() {
throw 1
}).then(null, function(value) {
o(value).equals(1)
done()
})
})
o("rejects on rejection error", function(done) {
var promise = Promise.resolve()
promise.then(function() {
throw 1
}).then(null, function() {
throw 2
}).then(null, function(value) {
o(value).equals(2)
done()
})
})
})
o.spec("promise absorption", function() {
o("absorbs resolved promise via static resolver", function(done) {
var promise = Promise.resolve(Promise.resolve(1))
promise.then(function(value) {
o(value).equals(1)
}).then(done)
})
o("absorbs resolved promise in executor resolve", function(done) {
var promise = new Promise(function(resolve, reject) {
resolve(Promise.resolve(1))
})
promise.then(function(value) {
o(value).equals(1)
done()
})
})
o("absorbs resolved promise on fulfillment", function(done) {
var promise = Promise.resolve()
promise.then(function() {
return Promise.resolve(1)
}).then(function(value) {
o(value).equals(1)
done()
})
})
o("absorbs rejected promise via static resolver", function(done) {
var promise = Promise.resolve(Promise.reject(1))
promise.then(null, function(value) {
o(value).equals(1)
done()
})
})
o("absorbs rejected promise in executor resolve", function(done) {
var promise = new Promise(function(resolve, reject) {
resolve(Promise.reject(1))
})
promise.then(null, function(value) {
o(value).equals(1)
done()
})
})
o("absorbs rejected promise on fulfillment", function(done) {
var promise = Promise.resolve()
promise.then(function() {
return Promise.reject(1)
}).then(null, function(value) {
o(value).equals(1)
done()
})
})
o("absorbs pending promise that resolves via static resolver", function(done) {
var pending = new Promise(function(resolve, reject) {
setTimeout(function() {resolve(1)}, 10)
})
var promise = Promise.resolve(pending)
promise.then(function(value) {
o(value).equals(1)
done()
})
})
o("absorbs pending promise that resolves in executor resolve", function(done) {
var pending = new Promise(function(resolve, reject) {
setTimeout(function() {resolve(1)}, 10)
})
var promise = new Promise(function(resolve, reject) {
resolve(pending)
})
promise.then(function(value) {
o(value).equals(1)
done()
})
})
o("absorbs pending promise that resolves on fulfillment", function(done) {
var pending = new Promise(function(resolve, reject) {
setTimeout(function() {resolve(1)}, 10)
})
var promise = Promise.resolve()
promise.then(function() {
return pending
}).then(function(value) {
o(value).equals(1)
done()
})
})
o("absorbs pending promise that rejects via static resolver", function(done) {
var pending = new Promise(function(resolve, reject) {
setTimeout(function() {reject(1)}, 10)
})
var promise = Promise.resolve(pending)
promise.then(null, function(value) {
o(value).equals(1)
done()
})
})
o("absorbs pending promise that rejects in executor resolve", function(done) {
var pending = new Promise(function(resolve, reject) {
setTimeout(function() {reject(1)}, 10)
})
var promise = new Promise(function(resolve, reject) {
resolve(pending)
})
promise.then(null, function(value) {
o(value).equals(1)
done()
})
})
o("absorbs pending promise that rejects on fulfillment", function(done) {
var pending = new Promise(function(resolve, reject) {
setTimeout(function() {reject(1)}, 10)
})
var promise = Promise.resolve()
promise.then(function() {
return pending
}).then(null, function(value) {
o(value).equals(1)
done()
})
})
o("does not absorb resolved promise via static rejector", function(done) {
var promise = Promise.reject(Promise.resolve(1))
promise.then(null, function(value) {
o(value instanceof Promise).equals(true)
done()
})
})
o("does not absorb rejected promise via static rejector", function(done) {
var rejected = Promise.reject(1)
rejected.catch(function() {})
var promise = Promise.reject(rejected)
promise.then(null, function(value) {
o(value instanceof Promise).equals(true)
done()
})
})
o("does not absorb resolved promise in executor reject", function(done) {
var promise = new Promise(function(resolve, reject) {
reject(Promise.resolve(1))
})
promise.then(null, function(value) {
o(value instanceof Promise).equals(true)
done()
})
})
o("does not absorb rejected promise in executor reject", function(done) {
var promise = new Promise(function(resolve, reject) {
var rejected = Promise.reject(1)
rejected.catch(function() {})
reject(rejected)
})
promise.then(null, function(value) {
o(value instanceof Promise).equals(true)
done()
})
})
o("does not absorb resolved promise on fulfillment error", function(done) {
var promise = Promise.resolve()
promise.then(function() {
throw Promise.resolve(1)
}).then(null, function(value) {
o(value instanceof Promise).equals(true)
done()
})
})
o("does not absorb rejected promise on fulfillment error", function(done) {
var promise = Promise.resolve()
promise.then(function() {
var rejected = Promise.reject(1)
rejected.catch(function() {})
throw rejected
}).then(null, function(value) {
o(value instanceof Promise).equals(true)
done()
})
})
})
o.spec("race", function() {
o("resolves to first resolved", function(done) {
var a = Promise.resolve(1)
var b = new Promise(function(resolve, reject) {
callAsync(function() {resolve(2)})
})
Promise.race([a, b]).then(function(value) {
o(value).equals(1)
done()
})
})
o("rejects to first rejected", function(done) {
var a = Promise.reject(1)
var b = new Promise(function(resolve, reject) {
callAsync(function() {reject(2)})
})
Promise.race([a, b]).then(null, function(value) {
o(value).equals(1)
done()
})
})
})
o.spec("all", function() {
o("resolves to array", function(done) {
var a = new Promise(function(resolve, reject) {
callAsync(function() {resolve(1)})
})
var b = Promise.resolve(2)
Promise.all([a, b]).then(function(value) {
o(value).deepEquals([1, 2])
done()
})
})
o("resolves non-promise to itself", function(done) {
var a = new Promise(function(resolve, reject) {
callAsync(function() {resolve(1)})
})
var b = Promise.resolve(2)
var c = 3
Promise.all([a, b, c]).then(function(value) {
o(value).deepEquals([1, 2, 3])
done()
})
})
o("rejects to first rejected", function(done) {
var a = Promise.reject(1)
var b = new Promise(function(resolve, reject) {
callAsync(function() {reject(2)})
})
Promise.all([a, b]).then(null, function(value) {
o(value).equals(1)
done()
})
})
})
})