284 lines
8.3 KiB
JavaScript
284 lines
8.3 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 data persistence using IE userData mechanism.
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* UserData uses proprietary Element.addBehavior(), Element.load(),
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* Element.save(), and Element.XMLDocument() methods, see:
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* http://msdn.microsoft.com/en-us/library/ms531424(v=vs.85).aspx.
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*
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*/
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goog.provide('goog.storage.mechanism.IEUserData');
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goog.require('goog.asserts');
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goog.require('goog.iter.Iterator');
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goog.require('goog.iter.StopIteration');
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goog.require('goog.storage.mechanism.ErrorCode');
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goog.require('goog.storage.mechanism.IterableMechanism');
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goog.require('goog.structs.Map');
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goog.require('goog.userAgent');
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/**
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* Provides a storage mechanism using IE userData.
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*
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* @param {string} storageKey The key (store name) to store the data under.
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* @param {string=} opt_storageNodeId The ID of the associated HTML element,
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* one will be created if not provided.
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* @constructor
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* @extends {goog.storage.mechanism.IterableMechanism}
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*/
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goog.storage.mechanism.IEUserData = function(storageKey, opt_storageNodeId) {
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goog.base(this);
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// Tested on IE6, IE7 and IE8. It seems that IE9 introduces some security
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// features which make persistent (loaded) node attributes invisible from
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// JavaScript.
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if (goog.userAgent.IE && !goog.userAgent.isDocumentModeOrHigher(9)) {
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if (!goog.storage.mechanism.IEUserData.storageMap_) {
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goog.storage.mechanism.IEUserData.storageMap_ = new goog.structs.Map();
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}
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this.storageNode_ = /** @type {Element} */ (
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goog.storage.mechanism.IEUserData.storageMap_.get(storageKey));
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if (!this.storageNode_) {
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if (opt_storageNodeId) {
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this.storageNode_ = document.getElementById(opt_storageNodeId);
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} else {
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this.storageNode_ = document.createElement('userdata');
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// This is a special IE-only method letting us persist data.
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this.storageNode_['addBehavior']('#default#userData');
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document.body.appendChild(this.storageNode_);
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}
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goog.storage.mechanism.IEUserData.storageMap_.set(
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storageKey, this.storageNode_);
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}
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this.storageKey_ = storageKey;
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/** @preserveTry */
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try {
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// Availability check.
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this.loadNode_();
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} catch (e) {
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this.storageNode_ = null;
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}
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}
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};
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goog.inherits(goog.storage.mechanism.IEUserData,
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goog.storage.mechanism.IterableMechanism);
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/**
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* Encoding map for characters which are not encoded by encodeURIComponent().
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* See encodeKey_ documentation for encoding details.
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*
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* @type {!Object}
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* @const
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*/
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goog.storage.mechanism.IEUserData.ENCODE_MAP = {
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'.': '.2E',
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'!': '.21',
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'~': '.7E',
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'*': '.2A',
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'\'': '.27',
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'(': '.28',
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')': '.29',
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'%': '.'
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};
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/**
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* Global storageKey to storageNode map, so we save on reloading the storage.
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*
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* @type {goog.structs.Map}
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* @private
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*/
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goog.storage.mechanism.IEUserData.storageMap_ = null;
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/**
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* The document element used for storing data.
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*
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* @type {Element}
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* @private
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*/
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goog.storage.mechanism.IEUserData.prototype.storageNode_ = null;
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/**
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* The key to store the data under.
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*
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* @type {?string}
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* @private
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*/
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goog.storage.mechanism.IEUserData.prototype.storageKey_ = null;
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/**
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* Encodes anything other than [-a-zA-Z0-9_] using a dot followed by hex,
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* and prefixes with underscore to form a valid and safe HTML attribute name.
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*
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* We use URI encoding to do the initial heavy lifting, then escape the
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* remaining characters that we can't use. Since a valid attribute name can't
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* contain the percent sign (%), we use a dot (.) as an escape character.
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*
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* @param {string} key The key to be encoded.
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* @return {string} The encoded key.
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* @private
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*/
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goog.storage.mechanism.IEUserData.encodeKey_ = function(key) {
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// encodeURIComponent leaves - _ . ! ~ * ' ( ) unencoded.
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return '_' + encodeURIComponent(key).replace(/[.!~*'()%]/g, function(c) {
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return goog.storage.mechanism.IEUserData.ENCODE_MAP[c];
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});
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};
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/**
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* Decodes a dot-encoded and character-prefixed key.
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* See encodeKey_ documentation for encoding details.
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*
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* @param {string} key The key to be decoded.
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* @return {string} The decoded key.
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* @private
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*/
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goog.storage.mechanism.IEUserData.decodeKey_ = function(key) {
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return decodeURIComponent(key.replace(/\./g, '%')).substr(1);
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};
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/**
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* Determines whether or not the mechanism is available.
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*
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* @return {boolean} True if the mechanism is available.
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*/
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goog.storage.mechanism.IEUserData.prototype.isAvailable = function() {
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return !!this.storageNode_;
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};
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/** @override */
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goog.storage.mechanism.IEUserData.prototype.set = function(key, value) {
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this.storageNode_.setAttribute(
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goog.storage.mechanism.IEUserData.encodeKey_(key), value);
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this.saveNode_();
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};
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/** @override */
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goog.storage.mechanism.IEUserData.prototype.get = function(key) {
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// According to Microsoft, values can be strings, numbers or booleans. Since
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// we only save strings, any other type is a storage error. If we returned
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// nulls for such keys, i.e., treated them as non-existent, this would lead
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// to a paradox where a key exists, but it does not when it is retrieved.
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// http://msdn.microsoft.com/en-us/library/ms531348(v=vs.85).aspx
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var value = this.storageNode_.getAttribute(
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goog.storage.mechanism.IEUserData.encodeKey_(key));
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if (!goog.isString(value) && !goog.isNull(value)) {
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throw goog.storage.mechanism.ErrorCode.INVALID_VALUE;
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}
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return value;
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};
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/** @override */
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goog.storage.mechanism.IEUserData.prototype.remove = function(key) {
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this.storageNode_.removeAttribute(
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goog.storage.mechanism.IEUserData.encodeKey_(key));
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this.saveNode_();
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};
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/** @override */
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goog.storage.mechanism.IEUserData.prototype.getCount = function() {
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return this.getNode_().attributes.length;
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};
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/** @override */
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goog.storage.mechanism.IEUserData.prototype.__iterator__ = function(opt_keys) {
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var i = 0;
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var attributes = this.getNode_().attributes;
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var newIter = new goog.iter.Iterator();
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newIter.next = function() {
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if (i >= attributes.length) {
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throw goog.iter.StopIteration;
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}
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var item = goog.asserts.assert(attributes[i++]);
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if (opt_keys) {
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return goog.storage.mechanism.IEUserData.decodeKey_(item.nodeName);
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}
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var value = item.nodeValue;
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// The value must exist and be a string, otherwise it is a storage error.
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if (!goog.isString(value)) {
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throw goog.storage.mechanism.ErrorCode.INVALID_VALUE;
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}
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return value;
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};
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return newIter;
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};
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/** @override */
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goog.storage.mechanism.IEUserData.prototype.clear = function() {
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var node = this.getNode_();
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for (var left = node.attributes.length; left > 0; left--) {
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node.removeAttribute(node.attributes[left - 1].nodeName);
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}
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this.saveNode_();
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};
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/**
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* Loads the underlying storage node to the state we saved it to before.
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*
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* @private
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*/
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goog.storage.mechanism.IEUserData.prototype.loadNode_ = function() {
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// This is a special IE-only method on Elements letting us persist data.
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this.storageNode_['load'](this.storageKey_);
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};
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/**
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* Saves the underlying storage node.
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*
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* @private
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*/
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goog.storage.mechanism.IEUserData.prototype.saveNode_ = function() {
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/** @preserveTry */
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try {
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// This is a special IE-only method on Elements letting us persist data.
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// Do not try to assign this.storageNode_['save'] to a variable, it does
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// not work. May throw an exception when the quota is exceeded.
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this.storageNode_['save'](this.storageKey_);
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} catch (e) {
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throw goog.storage.mechanism.ErrorCode.QUOTA_EXCEEDED;
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}
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};
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/**
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* Returns the storage node.
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*
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* @return {Element} Storage DOM Element.
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* @private
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*/
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goog.storage.mechanism.IEUserData.prototype.getNode_ = function() {
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// This is a special IE-only property letting us browse persistent data.
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var doc = /** @type {Document} */ (this.storageNode_['XMLDocument']);
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return doc.documentElement;
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};
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