enumerator.js
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import {
isArray,
isMaybeThenable
} from './utils';
import {
noop,
reject,
fulfill,
subscribe,
FULFILLED,
REJECTED,
PENDING,
handleMaybeThenable
} from './-internal';
import then from './then';
import Promise from './promise';
import originalResolve from './promise/resolve';
import originalThen from './then';
import { makePromise, PROMISE_ID } from './-internal';
function validationError() {
return new Error('Array Methods must be provided an Array');
};
export default class Enumerator {
constructor(Constructor, input) {
this._instanceConstructor = Constructor;
this.promise = new Constructor(noop);
if (!this.promise[PROMISE_ID]) {
makePromise(this.promise);
}
if (isArray(input)) {
this.length = input.length;
this._remaining = input.length;
this._result = new Array(this.length);
if (this.length === 0) {
fulfill(this.promise, this._result);
} else {
this.length = this.length || 0;
this._enumerate(input);
if (this._remaining === 0) {
fulfill(this.promise, this._result);
}
}
} else {
reject(this.promise, validationError());
}
}
_enumerate(input) {
for (let i = 0; this._state === PENDING && i < input.length; i++) {
this._eachEntry(input[i], i);
}
}
_eachEntry(entry, i) {
let c = this._instanceConstructor;
let { resolve } = c;
if (resolve === originalResolve) {
let then;
let error;
let didError = false;
try {
then = entry.then;
} catch (e) {
didError = true;
error = e;
}
if (then === originalThen &&
entry._state !== PENDING) {
this._settledAt(entry._state, i, entry._result);
} else if (typeof then !== 'function') {
this._remaining--;
this._result[i] = entry;
} else if (c === Promise) {
let promise = new c(noop);
if (didError) {
reject(promise, error);
} else {
handleMaybeThenable(promise, entry, then);
}
this._willSettleAt(promise, i);
} else {
this._willSettleAt(new c(resolve => resolve(entry)), i);
}
} else {
this._willSettleAt(resolve(entry), i);
}
}
_settledAt(state, i, value) {
let { promise } = this;
if (promise._state === PENDING) {
this._remaining--;
if (state === REJECTED) {
reject(promise, value);
} else {
this._result[i] = value;
}
}
if (this._remaining === 0) {
fulfill(promise, this._result);
}
}
_willSettleAt(promise, i) {
let enumerator = this;
subscribe(
promise, undefined,
value => enumerator._settledAt(FULFILLED, i, value),
reason => enumerator._settledAt(REJECTED, i, reason)
);
}
};