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