"use strict";
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/**
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* Queue for all the resources to be download except async scripts.
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* Async scripts have their own queue AsyncResourceQueue.
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*/
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module.exports = class ResourceQueue {
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constructor({ paused, asyncQueue } = {}) {
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this.paused = Boolean(paused);
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this._asyncQueue = asyncQueue;
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}
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getLastScript() {
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let head = this.tail;
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while (head) {
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if (head.isScript) {
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return head;
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}
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head = head.prev;
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}
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return null;
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}
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_moreScripts() {
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let found = false;
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let head = this.tail;
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while (head && !found) {
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found = head.isScript;
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head = head.prev;
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}
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return found;
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}
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_notify() {
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if (this._listener) {
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this._listener();
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}
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}
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setListener(listener) {
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this._listener = listener;
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}
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push(request, onLoad, onError, keepLast, element) {
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const isScript = element ? element.localName === "script" : false;
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if (!request) {
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if (isScript && !this._moreScripts()) {
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return onLoad();
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}
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request = Promise.resolve();
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}
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const q = this;
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const item = {
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isScript,
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err: null,
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element,
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fired: false,
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data: null,
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keepLast,
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prev: q.tail,
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check() {
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if (!q.paused && !this.prev && this.fired) {
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let promise;
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if (this.err && onError) {
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promise = onError(this.err);
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}
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if (!this.err && onLoad) {
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promise = onLoad(this.data);
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}
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Promise.resolve(promise)
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.then(() => {
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if (this.next) {
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this.next.prev = null;
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this.next.check();
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} else { // q.tail===this
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q.tail = null;
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q._notify();
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}
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this.finished = true;
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if (q._asyncQueue) {
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q._asyncQueue.notifyItem(this);
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}
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});
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}
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}
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};
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if (q.tail) {
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if (q.tail.keepLast) {
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// if the tail is the load event in document and we receive a new element to load
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// we should add this new request before the load event.
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if (q.tail.prev) {
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q.tail.prev.next = item;
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}
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item.prev = q.tail.prev;
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q.tail.prev = item;
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item.next = q.tail;
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} else {
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q.tail.next = item;
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q.tail = item;
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}
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} else {
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q.tail = item;
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}
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return request
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.then(data => {
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item.fired = 1;
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item.data = data;
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item.check();
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})
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.catch(err => {
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item.fired = true;
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item.err = err;
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item.check();
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});
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}
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resume() {
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if (!this.paused) {
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return;
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}
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this.paused = false;
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let head = this.tail;
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while (head && head.prev) {
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head = head.prev;
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}
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if (head) {
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head.check();
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}
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}
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};
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