112 lines
2.7 KiB
JavaScript
112 lines
2.7 KiB
JavaScript
// Copyright 2011 The Closure Library Authors. All Rights Reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS-IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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/**
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* @fileoverview Provides a convenient API for data persistence using a selected
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* data storage mechanism.
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*
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*/
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goog.provide('goog.storage.Storage');
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goog.require('goog.json');
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goog.require('goog.json.Serializer');
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goog.require('goog.storage.ErrorCode');
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/**
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* The base implementation for all storage APIs.
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*
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* @param {!goog.storage.mechanism.Mechanism} mechanism The underlying
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* storage mechanism.
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* @constructor
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*/
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goog.storage.Storage = function(mechanism) {
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this.mechanism = mechanism;
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this.serializer_ = new goog.json.Serializer();
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};
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/**
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* The mechanism used to persist key-value pairs.
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*
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* @type {goog.storage.mechanism.Mechanism}
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* @protected
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*/
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goog.storage.Storage.prototype.mechanism = null;
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/**
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* The JSON serializer used to serialize values.
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*
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* @type {goog.json.Serializer}
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* @private
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*/
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goog.storage.Storage.prototype.serializer_ = null;
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/**
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* Set an item in the data storage.
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*
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* @param {string} key The key to set.
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* @param {*} value The value to serialize to a string and save.
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*/
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goog.storage.Storage.prototype.set = function(key, value) {
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if (!goog.isDef(value)) {
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this.mechanism.remove(key);
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return;
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}
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this.mechanism.set(key, this.serializer_.serialize(value));
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};
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/**
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* Get an item from the data storage.
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*
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* @param {string} key The key to get.
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* @return {*} Deserialized value or undefined if not found.
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*/
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goog.storage.Storage.prototype.get = function(key) {
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var json;
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try {
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json = this.mechanism.get(key);
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} catch (e) {
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// If, for any reason, the value returned by a mechanism's get method is not
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// a string, an exception is thrown. In this case, we must fail gracefully
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// instead of propagating the exception to clients. See b/8095488 for
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// details.
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return undefined;
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}
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if (goog.isNull(json)) {
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return undefined;
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}
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/** @preserveTry */
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try {
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return goog.json.parse(json);
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} catch (e) {
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throw goog.storage.ErrorCode.INVALID_VALUE;
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}
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};
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/**
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* Remove an item from the data storage.
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*
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* @param {string} key The key to remove.
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*/
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goog.storage.Storage.prototype.remove = function(key) {
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this.mechanism.remove(key);
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};
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