40 lines
1.1 KiB
JavaScript
40 lines
1.1 KiB
JavaScript
'use strict'
|
|
|
|
const constants = require('./constants')
|
|
const unwrapSync = require('./unwrapSync')
|
|
|
|
// Behaves like a Promise, though the then() and catch() methods are unbound and
|
|
// must be called with the instance as their thisArg.
|
|
//
|
|
// The executor must either return a value or throw a rejection reason. It is
|
|
// not provided resolver or rejecter methods. The executor may return another
|
|
// thenable.
|
|
class Thenable {
|
|
constructor (executor) {
|
|
try {
|
|
this.result = unwrapSync(executor())
|
|
this.state = constants.RESOLVED
|
|
} catch (err) {
|
|
this.result = err
|
|
this.state = constants.REJECTED
|
|
}
|
|
}
|
|
|
|
then (onFulfilled, onRejected) {
|
|
if (this.state === constants.RESOLVED && typeof onFulfilled === 'function') {
|
|
return new Thenable(() => onFulfilled(this.result))
|
|
}
|
|
|
|
if (this.state === constants.REJECTED && typeof onRejected === 'function') {
|
|
return new Thenable(() => onRejected(this.result))
|
|
}
|
|
|
|
return this
|
|
}
|
|
|
|
catch (onRejected) {
|
|
return this.then(null, onRejected)
|
|
}
|
|
}
|
|
module.exports = Thenable
|