| // Copyright 2011 The Closure Library Authors. All Rights Reserved. |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS-IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| /** |
| * @fileoverview Provides factory methods for selecting the best storage |
| * mechanism, depending on availability and needs. |
| * |
| */ |
| |
| goog.provide('goog.storage.mechanism.mechanismfactory'); |
| |
| goog.require('goog.storage.mechanism.HTML5LocalStorage'); |
| goog.require('goog.storage.mechanism.HTML5SessionStorage'); |
| goog.require('goog.storage.mechanism.IEUserData'); |
| goog.require('goog.storage.mechanism.PrefixedMechanism'); |
| |
| |
| /** |
| * The key to shared userData storage. |
| * @type {string} |
| */ |
| goog.storage.mechanism.mechanismfactory.USER_DATA_SHARED_KEY = |
| 'UserDataSharedStore'; |
| |
| |
| /** |
| * Returns the best local storage mechanism, or null if unavailable. |
| * Local storage means that the database is placed on user's computer. |
| * The key-value database is normally shared between all the code paths |
| * that request it, so using an optional namespace is recommended. This |
| * provides separation and makes key collisions unlikely. |
| * |
| * @param {string=} opt_namespace Restricts the visibility to given namespace. |
| * @return {goog.storage.mechanism.IterableMechanism} Created mechanism or null. |
| */ |
| goog.storage.mechanism.mechanismfactory.create = function(opt_namespace) { |
| return goog.storage.mechanism.mechanismfactory.createHTML5LocalStorage( |
| opt_namespace) || |
| goog.storage.mechanism.mechanismfactory.createIEUserData(opt_namespace); |
| }; |
| |
| |
| /** |
| * Returns an HTML5 local storage mechanism, or null if unavailable. |
| * Since the HTML5 local storage does not support namespaces natively, |
| * and the key-value database is shared between all the code paths |
| * that request it, it is recommended that an optional namespace is |
| * used to provide key separation employing a prefix. |
| * |
| * @param {string=} opt_namespace Restricts the visibility to given namespace. |
| * @return {goog.storage.mechanism.IterableMechanism} Created mechanism or null. |
| */ |
| goog.storage.mechanism.mechanismfactory.createHTML5LocalStorage = function( |
| opt_namespace) { |
| var storage = new goog.storage.mechanism.HTML5LocalStorage(); |
| if (storage.isAvailable()) { |
| return opt_namespace ? new goog.storage.mechanism.PrefixedMechanism( |
| storage, opt_namespace) : storage; |
| } |
| return null; |
| }; |
| |
| |
| /** |
| * Returns an HTML5 session storage mechanism, or null if unavailable. |
| * Since the HTML5 session storage does not support namespaces natively, |
| * and the key-value database is shared between all the code paths |
| * that request it, it is recommended that an optional namespace is |
| * used to provide key separation employing a prefix. |
| * |
| * @param {string=} opt_namespace Restricts the visibility to given namespace. |
| * @return {goog.storage.mechanism.IterableMechanism} Created mechanism or null. |
| */ |
| goog.storage.mechanism.mechanismfactory.createHTML5SessionStorage = function( |
| opt_namespace) { |
| var storage = new goog.storage.mechanism.HTML5SessionStorage(); |
| if (storage.isAvailable()) { |
| return opt_namespace ? new goog.storage.mechanism.PrefixedMechanism( |
| storage, opt_namespace) : storage; |
| } |
| return null; |
| }; |
| |
| |
| /** |
| * Returns an IE userData local storage mechanism, or null if unavailable. |
| * Using an optional namespace is recommended to provide separation and |
| * avoid key collisions. |
| * |
| * @param {string=} opt_namespace Restricts the visibility to given namespace. |
| * @return {goog.storage.mechanism.IterableMechanism} Created mechanism or null. |
| */ |
| goog.storage.mechanism.mechanismfactory.createIEUserData = function( |
| opt_namespace) { |
| var storage = new goog.storage.mechanism.IEUserData(opt_namespace || |
| goog.storage.mechanism.mechanismfactory.USER_DATA_SHARED_KEY); |
| if (storage.isAvailable()) { |
| return storage; |
| } |
| return null; |
| }; |