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// 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 a convenient API for data persistence using a selected
* data storage mechanism.
*
*/
goog.provide('goog.storage.Storage');
goog.require('goog.json');
goog.require('goog.storage.ErrorCode');
/**
* The base implementation for all storage APIs.
*
* @param {!goog.storage.mechanism.Mechanism} mechanism The underlying
* storage mechanism.
* @constructor
* @struct
*/
goog.storage.Storage = function(mechanism) {
/**
* The mechanism used to persist key-value pairs.
*
* @protected {goog.storage.mechanism.Mechanism}
*/
this.mechanism = mechanism;
};
/**
* Sets an item in the data storage.
*
* @param {string} key The key to set.
* @param {*} value The value to serialize to a string and save.
*/
goog.storage.Storage.prototype.set = function(key, value) {
if (!goog.isDef(value)) {
this.mechanism.remove(key);
return;
}
this.mechanism.set(key, goog.json.serialize(value));
};
/**
* Gets an item from the data storage.
*
* @param {string} key The key to get.
* @return {*} Deserialized value or undefined if not found.
*/
goog.storage.Storage.prototype.get = function(key) {
var json;
try {
json = this.mechanism.get(key);
} catch (e) {
// If, for any reason, the value returned by a mechanism's get method is not
// a string, an exception is thrown. In this case, we must fail gracefully
// instead of propagating the exception to clients. See b/8095488 for
// details.
return undefined;
}
if (goog.isNull(json)) {
return undefined;
}
try {
return JSON.parse(json);
} catch (e) {
throw goog.storage.ErrorCode.INVALID_VALUE;
}
};
/**
* Removes an item from the data storage.
*
* @param {string} key The key to remove.
*/
goog.storage.Storage.prototype.remove = function(key) {
this.mechanism.remove(key);
};
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