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      1 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 cr.define('media', function() {
      6 
      7   /**
      8    * This class stores hashes by their id field and provides basic methods for
      9    * iterating over the collection.
     10    * @constructor
     11    */
     12   function ItemStore() {
     13     this.items_ = {};
     14   }
     15 
     16   ItemStore.prototype = {
     17     /**
     18      * Get a sorted list of item ids.
     19      * @return {Array} A sorted array of ids.
     20      */
     21     ids: function() {
     22       var ids = [];
     23       for (var i in this.items_)
     24         ids.push(i);
     25       return ids.sort();
     26     },
     27 
     28     /**
     29      * Add an item to the store.
     30      * @param {Object} item The item to be added.
     31      * @param {string} item.id The id of the item.
     32      */
     33     addItem: function(item) {
     34       this.items_[item.id] = item;
     35     },
     36 
     37     /**
     38      * Add a dictionary of items to the store.
     39      * @param {Object} items A dictionary of individual items. The keys are
     40      *    irrelevant but each must have an id field.
     41      */
     42     addItems: function(items) {
     43       for (id in items)
     44         this.addItem(items[id]);
     45     },
     46 
     47     /**
     48      * Remove an item from the store.
     49      * @param {string} id The id of the item to be removed.
     50      */
     51     removeItem: function(id) {
     52       delete this.items_[id];
     53     },
     54 
     55     /**
     56      * Map this itemStore to an Array. Items are sorted by id.
     57      * @param {function(*)} mapper The mapping function applied to each item.
     58      * @return {Array} An array of mapped items.
     59      */
     60     map: function(mapper) {
     61       var items = this.items_;
     62       var ids = this.ids();
     63       return ids.map(function(id) { return mapper(items[id]); });
     64     }
     65   };
     66 
     67   return {
     68     ItemStore: ItemStore
     69   };
     70 });
     71