promise.js
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/**
* Promises/A+ polyfill v1.1.4 (https://github.com/bramstein/promis)
*/
const RESOLVED = 0;
const REJECTED = 1;
const PENDING = 2;
import { nextTick } from '../util';
export default function Promise(executor) {
this.state = PENDING;
this.value = undefined;
this.deferred = [];
var promise = this;
try {
executor(function (x) {
promise.resolve(x);
}, function (r) {
promise.reject(r);
});
} catch (e) {
promise.reject(e);
}
}
Promise.reject = function (r) {
return new Promise(function (resolve, reject) {
reject(r);
});
};
Promise.resolve = function (x) {
return new Promise(function (resolve, reject) {
resolve(x);
});
};
Promise.all = function all(iterable) {
return new Promise(function (resolve, reject) {
var count = 0, result = [];
if (iterable.length === 0) {
resolve(result);
}
function resolver(i) {
return function (x) {
result[i] = x;
count += 1;
if (count === iterable.length) {
resolve(result);
}
};
}
for (var i = 0; i < iterable.length; i += 1) {
Promise.resolve(iterable[i]).then(resolver(i), reject);
}
});
};
Promise.race = function race(iterable) {
return new Promise(function (resolve, reject) {
for (var i = 0; i < iterable.length; i += 1) {
Promise.resolve(iterable[i]).then(resolve, reject);
}
});
};
var p = Promise.prototype;
p.resolve = function resolve(x) {
var promise = this;
if (promise.state === PENDING) {
if (x === promise) {
throw new TypeError('Promise settled with itself.');
}
var called = false;
try {
var then = x && x['then'];
if (x !== null && typeof x === 'object' && typeof then === 'function') {
then.call(x, function (x) {
if (!called) {
promise.resolve(x);
}
called = true;
}, function (r) {
if (!called) {
promise.reject(r);
}
called = true;
});
return;
}
} catch (e) {
if (!called) {
promise.reject(e);
}
return;
}
promise.state = RESOLVED;
promise.value = x;
promise.notify();
}
};
p.reject = function reject(reason) {
var promise = this;
if (promise.state === PENDING) {
if (reason === promise) {
throw new TypeError('Promise settled with itself.');
}
promise.state = REJECTED;
promise.value = reason;
promise.notify();
}
};
p.notify = function notify() {
var promise = this;
nextTick(function () {
if (promise.state !== PENDING) {
while (promise.deferred.length) {
var deferred = promise.deferred.shift(),
onResolved = deferred[0],
onRejected = deferred[1],
resolve = deferred[2],
reject = deferred[3];
try {
if (promise.state === RESOLVED) {
if (typeof onResolved === 'function') {
resolve(onResolved.call(undefined, promise.value));
} else {
resolve(promise.value);
}
} else if (promise.state === REJECTED) {
if (typeof onRejected === 'function') {
resolve(onRejected.call(undefined, promise.value));
} else {
reject(promise.value);
}
}
} catch (e) {
reject(e);
}
}
}
});
};
p.then = function then(onResolved, onRejected) {
var promise = this;
return new Promise(function (resolve, reject) {
promise.deferred.push([onResolved, onRejected, resolve, reject]);
promise.notify();
});
};
p.catch = function (onRejected) {
return this.then(undefined, onRejected);
};