text: // Copyright 2006 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
   * Implementations of DataNode for wrapping XML data.
   *
   */
  
  goog.provide('goog.ds.XmlDataSource');
  goog.provide('goog.ds.XmlHttpDataSource');
  
  goog.require('goog.Uri');
  goog.require('goog.dom.NodeType');
  goog.require('goog.dom.xml');
  goog.require('goog.ds.BasicNodeList');
  goog.require('goog.ds.DataManager');
  goog.require('goog.ds.LoadState');
  goog.require('goog.ds.logger');
  goog.require('goog.net.XhrIo');
  goog.require('goog.string');
  
  
  
  /**
   * Data source whose backing is an xml node
   *
   * @param {Node} node The XML node. Can be null.
   * @param {goog.ds.XmlDataSource} parent Parent of XML element. Can be null.
   * @param {string=} opt_name The name of this node relative to the parent node.
   *
   * @extends {goog.ds.DataNode}
   * @constructor
   */
  // TODO(arv): Use interfaces when available.
  goog.ds.XmlDataSource = function(node, parent, opt_name) {
    this.parent_ = parent;
    this.dataName_ = opt_name || (node ? node.nodeName : '');
    this.setNode_(node);
  };
  
  
  /**
   * Constant to select XML attributes for getChildNodes
   * @type {string}
   * @private
   */
  goog.ds.XmlDataSource.ATTRIBUTE_SELECTOR_ = '@*';
  
  
  /**
   * Set the current root nodeof the data source.
   * Can be an attribute node, text node, or element node
   * @param {Node} node The node. Can be null.
   *
   * @private
   */
  goog.ds.XmlDataSource.prototype.setNode_ = function(node) {
    this.node_ = node;
    if (node != null) {
      switch (node.nodeType) {
        case goog.dom.NodeType.ATTRIBUTE:
        case goog.dom.NodeType.TEXT:
          this.value_ = node.nodeValue;
          break;
        case goog.dom.NodeType.ELEMENT:
          if (node.childNodes.length == 1 &&
              node.firstChild.nodeType == goog.dom.NodeType.TEXT) {
            this.value_ = node.firstChild.nodeValue;
          }
      }
    }
  };
  
  
  /**
   * Creates the DataNodeList with the child nodes for this element.
   * Allows for only building list as needed.
   *
   * @private
   */
  goog.ds.XmlDataSource.prototype.createChildNodes_ = function() {
    if (this.childNodeList_) {
      return;
    }
    var childNodeList = new goog.ds.BasicNodeList();
    if (this.node_ != null) {
      var childNodes = this.node_.childNodes;
      for (var i = 0, childNode; childNode = childNodes[i]; i++) {
        if (childNode.nodeType != goog.dom.NodeType.TEXT ||
            !goog.ds.XmlDataSource.isEmptyTextNodeValue_(childNode.nodeValue)) {
          var newNode = new goog.ds.XmlDataSource(childNode,
              this, childNode.nodeName);
          childNodeList.add(newNode);
        }
      }
    }
    this.childNodeList_ = childNodeList;
  };
  
  
  /**
   * Creates the DataNodeList with the attributes for the element
   * Allows for only building list as needed.
   *
   * @private
   */
  goog.ds.XmlDataSource.prototype.createAttributes_ = function() {
    if (this.attributes_) {
      return;
    }
    var attributes = new goog.ds.BasicNodeList();
    if (this.node_ != null && this.node_.attributes != null) {
      var atts = this.node_.attributes;
      for (var i = 0, att; att = atts[i]; i++) {
        var newNode = new goog.ds.XmlDataSource(att, this, att.nodeName);
        attributes.add(newNode);
      }
    }
    this.attributes_ = attributes;
  };
  
  
  /**
   * Get the value of the node
   * @return {Object} The value of the node, or null if no value.
   * @override
   */
  goog.ds.XmlDataSource.prototype.get = function() {
    this.createChildNodes_();
    return this.value_;
  };
  
  
  /**
   * Set the value of the node
   * @param {*} value The new value of the node.
   * @override
   */
  goog.ds.XmlDataSource.prototype.set = function(value) {
    throw Error('Can\'t set on XmlDataSource yet');
  };
  
  
  /** @override */
  goog.ds.XmlDataSource.prototype.getChildNodes = function(opt_selector) {
    if (opt_selector && opt_selector ==
        goog.ds.XmlDataSource.ATTRIBUTE_SELECTOR_) {
      this.createAttributes_();
      return this.attributes_;
    } else if (opt_selector == null ||
        opt_selector == goog.ds.STR_ALL_CHILDREN_SELECTOR) {
      this.createChildNodes_();
      return this.childNodeList_;
    } else {
      throw Error('Unsupported selector');
    }
  
  };
  
  
  /**
   * Gets a named child node of the current node
   * @param {string} name The node name.
   * @return {goog.ds.DataNode} The child node, or null if
   *   no node of this name exists.
   * @override
   */
  goog.ds.XmlDataSource.prototype.getChildNode = function(name) {
    if (goog.string.startsWith(name, goog.ds.STR_ATTRIBUTE_START)) {
      var att = this.node_.getAttributeNode(name.substring(1));
      return att ? new goog.ds.XmlDataSource(att, this) : null;
    } else {
      return /** @type {goog.ds.DataNode} */ (this.getChildNodes().get(name));
    }
  };
  
  
  /**
   * Gets the value of a child node
   * @param {string} name The node name.
   * @return {*} The value of the node, or null if no value or the child node
   *    doesn't exist.
   * @override
   */
  goog.ds.XmlDataSource.prototype.getChildNodeValue = function(name) {
    if (goog.string.startsWith(name, goog.ds.STR_ATTRIBUTE_START)) {
      var node = this.node_.getAttributeNode(name.substring(1));
      return node ? node.nodeValue : null;
    } else {
      var node = this.getChildNode(name);
      return node ? node.get() : null;
    }
  };
  
  
  /**
   * Get the name of the node relative to the parent node
   * @return {string} The name of the node.
   * @override
   */
  goog.ds.XmlDataSource.prototype.getDataName = function() {
    return this.dataName_;
  };
  
  
  /**
   * Setthe name of the node relative to the parent node
   * @param {string} name The name of the node.
   * @override
   */
  goog.ds.XmlDataSource.prototype.setDataName = function(name) {
    this.dataName_ = name;
  };
  
  
  /**
   * Gets the a qualified data path to this node
   * @return {string} The data path.
   * @override
   */
  goog.ds.XmlDataSource.prototype.getDataPath = function() {
    var parentPath = '';
    if (this.parent_) {
      parentPath = this.parent_.getDataPath() +
          (this.dataName_.indexOf(goog.ds.STR_ARRAY_START) != -1 ? '' :
          goog.ds.STR_PATH_SEPARATOR);
    }
  
    return parentPath + this.dataName_;
  };
  
  
  /**
   * Load or reload the backing data for this node
   * @override
   */
  goog.ds.XmlDataSource.prototype.load = function() {
    // Nothing to do
  };
  
  
  /**
   * Gets the state of the backing data for this node
   * @return {goog.ds.LoadState} The state.
   * @override
   */
  goog.ds.XmlDataSource.prototype.getLoadState = function() {
    return this.node_ ? goog.ds.LoadState.LOADED : goog.ds.LoadState.NOT_LOADED;
  };
  
  
  /**
   * Check whether a node is an empty text node. Nodes consisting of only white
   * space (#x20, #xD, #xA, #x9) can generally be collapsed to a zero length
   * text string.
   * @param {string} str String to match.
   * @return {boolean} True if string equates to empty text node.
   * @private
   */
  goog.ds.XmlDataSource.isEmptyTextNodeValue_ = function(str) {
    return /^[\r\n\t ]*$/.test(str);
  };
  
  
  /**
   * Creates an XML document with one empty node.
   * Useful for places where you need a node that
   * can be queried against.
   *
   * @return {Document} Document with one empty node.
   * @private
   */
  goog.ds.XmlDataSource.createChildlessDocument_ = function() {
    return goog.dom.xml.createDocument('nothing');
  };
  
  
  
  /**
   * Data source whose backing is an XMLHttpRequest,
   *
   * A URI of an empty string will mean that no request is made
   * and the data source will be a single, empty node.
   *
   * @param {(string,goog.Uri)} uri URL of the XMLHttpRequest.
   * @param {string} name Name of the datasource.
   *
   * implements goog.ds.XmlHttpDataSource.
   * @constructor
   * @extends {goog.ds.XmlDataSource}
   */
  goog.ds.XmlHttpDataSource = function(uri, name) {
    goog.ds.XmlDataSource.call(this, null, null, name);
    if (uri) {
      this.uri_ = new goog.Uri(uri);
    } else {
      this.uri_ = null;
    }
  };
  goog.inherits(goog.ds.XmlHttpDataSource, goog.ds.XmlDataSource);
  
  
  /**
   * Default load state is NOT_LOADED
   * @private
   */
  goog.ds.XmlHttpDataSource.prototype.loadState_ = goog.ds.LoadState.NOT_LOADED;
  
  
  /**
   * Load or reload the backing data for this node.
   * Fires the XMLHttpRequest
   * @override
   */
  goog.ds.XmlHttpDataSource.prototype.load = function() {
    if (this.uri_) {
      goog.log.info(goog.ds.logger, 'Sending XML request for DataSource ' +
          this.getDataName() + ' to ' + this.uri_);
      this.loadState_ = goog.ds.LoadState.LOADING;
  
      goog.net.XhrIo.send(this.uri_, goog.bind(this.complete_, this));
    } else {
      this.node_ = goog.ds.XmlDataSource.createChildlessDocument_();
      this.loadState_ = goog.ds.LoadState.NOT_LOADED;
    }
  };
  
  
  /**
   * Gets the state of the backing data for this node
   * @return {goog.ds.LoadState} The state.
   * @override
   */
  goog.ds.XmlHttpDataSource.prototype.getLoadState = function() {
    return this.loadState_;
  };
  
  
  /**
   * Handles the completion of an XhrIo request. Dispatches to success or load
   * based on the result.
   * @param {!goog.events.Event} e The XhrIo event object.
   * @private
   */
  goog.ds.XmlHttpDataSource.prototype.complete_ = function(e) {
    var xhr = /** @type {goog.net.XhrIo} */ (e.target);
    if (xhr && xhr.isSuccess()) {
      this.success_(xhr);
    } else {
      this.failure_();
    }
  };
  
  
  /**
   * Success result. Checks whether valid XML was returned
   * and sets the XML and loadstate.
   *
   * @param {!goog.net.XhrIo} xhr The successful XhrIo object.
   * @private
   */
  goog.ds.XmlHttpDataSource.prototype.success_ = function(xhr) {
    goog.log.info(goog.ds.logger,
        'Got data for DataSource ' + this.getDataName());
    var xml = xhr.getResponseXml();
  
    // Fix for case where IE returns valid XML as text but
    // doesn't parse by default
    if (xml && !xml.hasChildNodes() &&
        goog.isObject(xhr.getResponseText())) {
      xml = goog.dom.xml.loadXml(xhr.getResponseText());
    }
    // Failure result
    if (!xml || !xml.hasChildNodes()) {
      this.loadState_ = goog.ds.LoadState.FAILED;
      this.node_ = goog.ds.XmlDataSource.createChildlessDocument_();
    } else {
      this.loadState_ = goog.ds.LoadState.LOADED;
      this.node_ = xml.documentElement;
    }
  
    if (this.getDataName()) {
      goog.ds.DataManager.getInstance().fireDataChange(this.getDataName());
    }
  };
  
  
  /**
   * Failure result
   *
   * @private
   */
  goog.ds.XmlHttpDataSource.prototype.failure_ = function() {
    goog.log.info(goog.ds.logger, 'Data retrieve failed for DataSource ' +
        this.getDataName());
  
    this.loadState_ = goog.ds.LoadState.FAILED;
    this.node_ = goog.ds.XmlDataSource.createChildlessDocument_();
  
    if (this.getDataName()) {
      goog.ds.DataManager.getInstance().fireDataChange(this.getDataName());
    }
  };
  