    /**
     * @author Ed Spencer
     * @class Ext.data.reader.Xml
     * @extends Ext.data.reader.Reader
     *
     * <p>The XML Reader is used by a Proxy to read a server response that is sent back in XML format. This usually
     * happens as a result of loading a Store - for example we might create something like this:</p>
     *
    <pre><code>
    Ext.define('User', {
        extend: 'Ext.data.Model',
        fields: ['id', 'name', 'email']
    });

    var store = new Ext.data.Store({
        model: 'User',
        proxy: {
            type: 'ajax',
            url : 'users.xml',
            reader: {
                type: 'xml',
                record: 'user'
            }
        }
    });
    </code></pre>
     *
     * <p>The example above creates a 'User' model. Models are explained in the {@link Ext.data.Model Model} docs if you're
     * not already familiar with them.</p>
     *
     * <p>We created the simplest type of XML Reader possible by simply telling our {@link Ext.data.Store Store}'s
     * {@link Ext.data.proxy.Proxy Proxy} that we want a XML Reader. The Store automatically passes the configured model to the
     * Store, so it is as if we passed this instead:
     *
    <pre><code>
    reader: {
        type : 'xml',
        model: 'User',
        record: 'user'
    }
    </code></pre>
     *
     * <p>The reader we set up is ready to read data from our server - at the moment it will accept a response like this:</p>
     *
    <pre><code>
    &lt;?xml version="1.0" encoding="UTF-8"?&gt;
    &lt;user&gt;
        &lt;id&gt;1&lt;/id&gt;
        &lt;name&gt;Ed Spencer&lt;/name&gt;
        &lt;email&gt;ed@sencha.com&lt;/email&gt;
    &lt;/user&gt;
    &lt;user&gt;
        &lt;id&gt;2&lt;/id&gt;
        &lt;name&gt;Abe Elias&lt;/name&gt;
        &lt;email&gt;abe@sencha.com&lt;/email&gt;
    &lt;/user&gt;
    </code></pre>
     *
     * <p>The XML Reader uses the configured {@link #record} option to pull out the data for each record - in this case we
     * set record to 'user', so each &lt;user&gt; above will be converted into a User model.</p>
     *
     * <p><u>Reading other XML formats</u></p>
     *
     * <p>If you already have your XML format defined and it doesn't look quite like what we have above, you can usually
     * pass XmlReader a couple of configuration options to make it parse your format. For example, we can use the
     * {@link #root} configuration to parse data that comes back like this:</p>
     *
    <pre><code>
    &lt;?xml version="1.0" encoding="UTF-8"?&gt;
    &lt;users&gt;
        &lt;user&gt;
            &lt;id&gt;1&lt;/id&gt;
            &lt;name&gt;Ed Spencer&lt;/name&gt;
            &lt;email&gt;ed@sencha.com&lt;/email&gt;
        &lt;/user&gt;
        &lt;user&gt;
            &lt;id&gt;2&lt;/id&gt;
            &lt;name&gt;Abe Elias&lt;/name&gt;
            &lt;email&gt;abe@sencha.com&lt;/email&gt;
        &lt;/user&gt;
    &lt;/users&gt;
    </code></pre>
     *
     * <p>To parse this we just pass in a {@link #root} configuration that matches the 'users' above:</p>
     *
    <pre><code>
    reader: {
        type  : 'xml',
        root  : 'users',
        record: 'user'
    }
    </code></pre>
     *
     * <p>Note that XmlReader doesn't care whether your {@link #root} and {@link #record} elements are nested deep inside
     * a larger structure, so a response like this will still work:
     *
    <pre><code>
    &lt;?xml version="1.0" encoding="UTF-8"?&gt;
    &lt;deeply&gt;
        &lt;nested&gt;
            &lt;xml&gt;
                &lt;users&gt;
                    &lt;user&gt;
                        &lt;id&gt;1&lt;/id&gt;
                        &lt;name&gt;Ed Spencer&lt;/name&gt;
                        &lt;email&gt;ed@sencha.com&lt;/email&gt;
                    &lt;/user&gt;
                    &lt;user&gt;
                        &lt;id&gt;2&lt;/id&gt;
                        &lt;name&gt;Abe Elias&lt;/name&gt;
                        &lt;email&gt;abe@sencha.com&lt;/email&gt;
                    &lt;/user&gt;
                &lt;/users&gt;
            &lt;/xml&gt;
        &lt;/nested&gt;
    &lt;/deeply&gt;
    </code></pre>
     *
     * <p><u>Response metadata</u></p>
     *
     * <p>The server can return additional data in its response, such as the {@link #totalProperty total number of records}
     * and the {@link #successProperty success status of the response}. These are typically included in the XML response
     * like this:</p>
     *
    <pre><code>
    &lt;?xml version="1.0" encoding="UTF-8"?&gt;
    &lt;total&gt;100&lt;/total&gt;
    &lt;success&gt;true&lt;/success&gt;
    &lt;users&gt;
        &lt;user&gt;
            &lt;id&gt;1&lt;/id&gt;
            &lt;name&gt;Ed Spencer&lt;/name&gt;
            &lt;email&gt;ed@sencha.com&lt;/email&gt;
        &lt;/user&gt;
        &lt;user&gt;
            &lt;id&gt;2&lt;/id&gt;
            &lt;name&gt;Abe Elias&lt;/name&gt;
            &lt;email&gt;abe@sencha.com&lt;/email&gt;
        &lt;/user&gt;
    &lt;/users&gt;
    </code></pre>
     *
     * <p>If these properties are present in the XML response they can be parsed out by the XmlReader and used by the
     * Store that loaded it. We can set up the names of these properties by specifying a final pair of configuration
     * options:</p>
     *
    <pre><code>
    reader: {
        type: 'xml',
        root: 'users',
        totalProperty  : 'total',
        successProperty: 'success'
    }
    </code></pre>
     *
     * <p>These final options are not necessary to make the Reader work, but can be useful when the server needs to report
     * an error or if it needs to indicate that there is a lot of data available of which only a subset is currently being
     * returned.</p>
     *
     * <p><u>Response format</u></p>
     *
     * <p><b>Note:</b> in order for the browser to parse a returned XML document, the Content-Type header in the HTTP
     * response must be set to "text/xml" or "application/xml". This is very important - the XmlReader will not
     * work correctly otherwise.</p>
     */
    Ext.define('Ext.data.reader.Xml', {
        extend: 'Ext.data.reader.Reader',
        alternateClassName: 'Ext.data.XmlReader',
        alias : 'reader.xml',

        /**
         * @cfg {String} record The DomQuery path to the repeated element which contains record information.
         */

        /**
         * @private
         * Creates a function to return some particular key of data from a response. The totalProperty and
         * successProperty are treated as special cases for type casting, everything else is just a simple selector.
         * @param {String} key
         * @return {Function}
         */
        createAccessor: function(expr) {
            var me = this;

            if (Ext.isEmpty(expr)) {
                return Ext.emptyFn;
            }

            if (Ext.isFunction(expr)) {
                return expr;
            }

            return function(root) {
                var node = Ext.DomQuery.selectNode(expr, root),
                    val = me.getNodeValue(node);

                return Ext.isEmpty(val) ? null : val;
            };
        },

        getNodeValue: function(node) {
            var val;
            if (node && node.firstChild) {
                val = node.firstChild.nodeValue;
            }
            return val || null;
        },

        //inherit docs
        getResponseData: function(response) {
            var xml = response.responseXML;

            //<debug>
            if (!xml) {
                Ext.Error.raise({
                    response: response,
                    msg: 'XML data not found in the response'
                });
            }
            //</debug>

            return xml;
        },

        /**
         * Normalizes the data object
         * @param {Object} data The raw data object
         * @return {Object} Returns the documentElement property of the data object if present, or the same object if not
         */
        getData: function(data) {
            return data.documentElement || data;
        },

        /**
         * @private
         * Given an XML object, returns the Element that represents the root as configured by the Reader's meta data
         * @param {Object} data The XML data object
         * @return {Element} The root node element
         */
        getRoot: function(data) {
            var nodeName = data.nodeName,
                root     = this.root;

            if (!root || (nodeName && nodeName == root)) {
                return data;
            } else if (Ext.DomQuery.isXml(data)) {
                // This fix ensures we have XML data
                // Related to TreeStore calling getRoot with the root node, which isn't XML
                // Probably should be resolved in TreeStore at some point
                return Ext.DomQuery.selectNode(root, data);
            }
        },

        /**
         * @private
         * We're just preparing the data for the superclass by pulling out the record nodes we want
         * @param {Element} root The XML root node
         * @return {Array} The records
         */
        extractData: function(root) {
            var recordName = this.record;

            //<debug>
            if (!recordName) {
                Ext.Error.raise('Record is a required parameter');
            }
            //</debug>

            if (recordName != root.nodeName) {
                root = Ext.DomQuery.select(recordName, root);
            } else {
                root = [root];
            }
            return this.callParent([root]);
        },

        /**
         * @private
         * See Ext.data.reader.Reader's getAssociatedDataRoot docs
         * @param {Mixed} data The raw data object
         * @param {String} associationName The name of the association to get data for (uses associationKey if present)
         * @return {Mixed} The root
         */
        getAssociatedDataRoot: function(data, associationName) {
            return Ext.DomQuery.select(associationName, data)[0];
        },

        /**
         * Parses an XML document and returns a ResultSet containing the model instances
         * @param {Object} doc Parsed XML document
         * @return {Ext.data.ResultSet} The parsed result set
         */
        readRecords: function(doc) {
            //it's possible that we get passed an array here by associations. Make sure we strip that out (see Ext.data.reader.Reader#readAssociated)
            if (Ext.isArray(doc)) {
                doc = doc[0];
            }

            /**
             * DEPRECATED - will be removed in Ext JS 5.0. This is just a copy of this.rawData - use that instead
             * @property xmlData
             * @type Object
             */
            this.xmlData = doc;
            return this.callParent([doc]);
        }
    });