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// Copyright 2006 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
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 * XML utilities.
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 *
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 */
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goog.provide('goog.dom.xml');
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goog.require('goog.dom');
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goog.require('goog.dom.NodeType');
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goog.require('goog.userAgent');
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/**
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 * Max XML size for MSXML2.  Used to prevent potential DoS attacks.
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 * @type {number}
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 */
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goog.dom.xml.MAX_XML_SIZE_KB = 2 * 1024;  // In kB
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/**
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 * Max XML size for MSXML2.  Used to prevent potential DoS attacks.
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 * @type {number}
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 */
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goog.dom.xml.MAX_ELEMENT_DEPTH = 256;  // Same default as MSXML6.
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/**
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 * Check for ActiveXObject support by the browser.
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 * @return {boolean} true if browser has ActiveXObject support.
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 * @private
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 */
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goog.dom.xml.hasActiveXObjectSupport_ = function() {
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  if (!goog.userAgent.IE) {
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    // Avoid raising useless exception in case code is not compiled
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    // and browser is not MSIE.
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    return false;
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  }
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  try {
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    // Due to lot of changes in IE 9, 10 & 11 behaviour and ActiveX being
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    // totally disableable using MSIE's security level, trying to create the
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    // ActiveXOjbect is a lot more reliable than testing for the existence of
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    // window.ActiveXObject
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    new ActiveXObject('MSXML2.DOMDocument');
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    return true;
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  } catch (e) {
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    return false;
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  }
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};
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/**
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 * True if browser has ActiveXObject support.
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 * Possible override if this test become wrong in coming IE versions.
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 * @type {boolean}
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 */
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goog.dom.xml.ACTIVEX_SUPPORT =
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    goog.userAgent.IE && goog.dom.xml.hasActiveXObjectSupport_();
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/**
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 * Creates an XML document appropriate for the current JS runtime
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 * @param {string=} opt_rootTagName The root tag name.
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 * @param {string=} opt_namespaceUri Namespace URI of the document element.
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 * @param {boolean=} opt_preferActiveX Whether to default to ActiveXObject to
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 * create Document in IE. Use this if you need xpath support in IE (e.g.,
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 * selectSingleNode or selectNodes), but be aware that the ActiveXObject does
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 * not support various DOM-specific Document methods and attributes.
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 * @return {Document} The new document.
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 * @throws {Error} if browser does not support creating new documents or
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 * namespace is provided without a root tag name.
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 */
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goog.dom.xml.createDocument = function(
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    opt_rootTagName, opt_namespaceUri, opt_preferActiveX) {
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  if (opt_namespaceUri && !opt_rootTagName) {
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    throw Error("Can't create document with namespace and no root tag");
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  }
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  // If document.implementation.createDocument is available and they haven't
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  // explicitly opted to use ActiveXObject when possible.
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  if (document.implementation && document.implementation.createDocument &&
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      !(goog.dom.xml.ACTIVEX_SUPPORT && opt_preferActiveX)) {
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    return document.implementation.createDocument(
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        opt_namespaceUri || '', opt_rootTagName || '', null);
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  } else if (goog.dom.xml.ACTIVEX_SUPPORT) {
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    var doc = goog.dom.xml.createMsXmlDocument_();
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    if (doc) {
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      if (opt_rootTagName) {
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        doc.appendChild(
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            doc.createNode(
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                goog.dom.NodeType.ELEMENT, opt_rootTagName,
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                opt_namespaceUri || ''));
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      }
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      return doc;
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    }
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  }
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  throw Error('Your browser does not support creating new documents');
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};
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/**
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 * Creates an XML document from a string
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 * @param {string} xml The text.
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 * @param {boolean=} opt_preferActiveX Whether to default to ActiveXObject to
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 * create Document in IE. Use this if you need xpath support in IE (e.g.,
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 * selectSingleNode or selectNodes), but be aware that the ActiveXObject does
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 * not support various DOM-specific Document methods and attributes.
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 * @return {Document} XML document from the text.
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 * @throws {Error} if browser does not support loading XML documents.
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 */
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goog.dom.xml.loadXml = function(xml, opt_preferActiveX) {
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  if (typeof DOMParser != 'undefined' &&
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      !(goog.dom.xml.ACTIVEX_SUPPORT && opt_preferActiveX)) {
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    return new DOMParser().parseFromString(xml, 'application/xml');
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  } else if (goog.dom.xml.ACTIVEX_SUPPORT) {
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    var doc = goog.dom.xml.createMsXmlDocument_();
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    doc.loadXML(xml);
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    return doc;
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  }
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  throw Error('Your browser does not support loading xml documents');
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};
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/**
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 * Serializes an XML document or subtree to string.
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 * @param {Document|Element} xml The document or the root node of the subtree.
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 * @return {string} The serialized XML.
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 * @throws {Error} if browser does not support XML serialization.
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 */
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goog.dom.xml.serialize = function(xml) {
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  // Compatible with IE/ActiveXObject.
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  var text = xml.xml;
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  if (text) {
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    return text;
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  }
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  // Compatible with Firefox, Opera and WebKit.
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  if (typeof XMLSerializer != 'undefined') {
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    return new XMLSerializer().serializeToString(xml);
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  }
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  throw Error('Your browser does not support serializing XML documents');
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};
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/**
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 * Selects a single node using an Xpath expression and a root node
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 * @param {Node} node The root node.
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 * @param {string} path Xpath selector.
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 * @return {Node} The selected node, or null if no matching node.
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 */
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goog.dom.xml.selectSingleNode = function(node, path) {
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  if (typeof node.selectSingleNode != 'undefined') {
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    var doc = goog.dom.getOwnerDocument(node);
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    if (typeof doc.setProperty != 'undefined') {
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      doc.setProperty('SelectionLanguage', 'XPath');
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    }
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    return node.selectSingleNode(path);
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  } else if (document.implementation.hasFeature('XPath', '3.0')) {
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    var doc = goog.dom.getOwnerDocument(node);
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    var resolver = doc.createNSResolver(doc.documentElement);
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    var result = doc.evaluate(
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        path, node, resolver, XPathResult.FIRST_ORDERED_NODE_TYPE, null);
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    return result.singleNodeValue;
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  }
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  // This browser does not support xpath for the given node. If IE, ensure XML
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  // Document was created using ActiveXObject
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  // TODO(joeltine): This should throw instead of return null.
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  return null;
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};
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/**
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 * Selects multiple nodes using an Xpath expression and a root node
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 * @param {Node} node The root node.
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 * @param {string} path Xpath selector.
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 * @return {(!NodeList<!Node>|!Array<!Node>)} The selected nodes, or empty array
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 *     if no matching nodes.
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 */
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goog.dom.xml.selectNodes = function(node, path) {
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  if (typeof node.selectNodes != 'undefined') {
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    var doc = goog.dom.getOwnerDocument(node);
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    if (typeof doc.setProperty != 'undefined') {
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      doc.setProperty('SelectionLanguage', 'XPath');
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    }
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    return node.selectNodes(path);
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  } else if (document.implementation.hasFeature('XPath', '3.0')) {
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    var doc = goog.dom.getOwnerDocument(node);
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    var resolver = doc.createNSResolver(doc.documentElement);
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    var nodes = doc.evaluate(
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        path, node, resolver, XPathResult.ORDERED_NODE_SNAPSHOT_TYPE, null);
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    var results = [];
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    var count = nodes.snapshotLength;
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    for (var i = 0; i < count; i++) {
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      results.push(nodes.snapshotItem(i));
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    }
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    return results;
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  } else {
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    // This browser does not support xpath for the given node. If IE, ensure XML
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    // Document was created using ActiveXObject.
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    // TODO(joeltine): This should throw instead of return empty array.
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    return [];
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  }
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};
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/**
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 * Sets multiple attributes on an element. Differs from goog.dom.setProperties
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 * in that it exclusively uses the element's setAttributes method. Use this
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 * when you need to ensure that the exact property is available as an attribute
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 * and can be read later by the native getAttribute method.
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 * @param {!Element} element XML or DOM element to set attributes on.
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 * @param {!Object<string, string>} attributes Map of property:value pairs.
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 */
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goog.dom.xml.setAttributes = function(element, attributes) {
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  for (var key in attributes) {
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    if (attributes.hasOwnProperty(key)) {
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      element.setAttribute(key, attributes[key]);
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    }
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  }
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};
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/**
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 * Creates an instance of the MSXML2.DOMDocument.
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 * @return {Document} The new document.
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 * @private
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 */
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goog.dom.xml.createMsXmlDocument_ = function() {
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  var doc = new ActiveXObject('MSXML2.DOMDocument');
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  if (doc) {
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    // Prevent potential vulnerabilities exposed by MSXML2, see
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    // http://b/1707300 and http://wiki/Main/ISETeamXMLAttacks for details.
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    doc.resolveExternals = false;
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    doc.validateOnParse = false;
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    // Add a try catch block because accessing these properties will throw an
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    // error on unsupported MSXML versions. This affects Windows machines
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    // running IE6 or IE7 that are on XP SP2 or earlier without MSXML updates.
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    // See http://msdn.microsoft.com/en-us/library/ms766391(VS.85).aspx for
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    // specific details on which MSXML versions support these properties.
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    try {
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      doc.setProperty('ProhibitDTD', true);
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      doc.setProperty('MaxXMLSize', goog.dom.xml.MAX_XML_SIZE_KB);
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      doc.setProperty('MaxElementDepth', goog.dom.xml.MAX_ELEMENT_DEPTH);
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    } catch (e) {
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      // No-op.
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    }
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  }
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  return doc;
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};
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