gecko-dev/dom/settings/SettingsQueue.jsm

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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this file,
* You can obtain one at http://mozilla.org/MPL/2.0/. */
this.EXPORTED_SYMBOLS = ["Queue"];
this.Queue = function Queue() {
this._queue = [];
this._index = 0;
}
Queue.prototype = {
getLength: function() { return (this._queue.length - this._index); },
isEmpty: function() { return (this._queue.length == 0); },
enqueue: function(item) { this._queue.push(item); },
dequeue: function() {
if(this.isEmpty())
return undefined;
var item = this._queue[this._index];
if (++this._index * 2 >= this._queue.length){
this._queue = this._queue.slice(this._index);
this._index = 0;
}
return item;
}
}