    /**
     * @class Ext.state.Provider
     * <p>Abstract base class for state provider implementations. The provider is responsible
     * for setting values  and extracting values to/from the underlying storage source. The
     * storage source can vary and the details should be implemented in a subclass. For example
     * a provider could use a server side database or the browser localstorage where supported.</p>
     *
     * <p>This class provides methods for encoding and decoding <b>typed</b> variables including
     * dates and defines the Provider interface. By default these methods put the value and the
     * type information into a delimited string that can be stored. These should be overridden in
     * a subclass if you want to change the format of the encoded value and subsequent decoding.</p>
     */
    Ext.define('Ext.state.Provider', {
        mixins: {
            observable: 'Ext.util.Observable'
        },

        /**
         * @cfg {String} prefix A string to prefix to items stored in the underlying state store.
         * Defaults to <tt>'ext-'</tt>
         */
        prefix: 'ext-',

        constructor : function(config){
            config = config || {};
            var me = this;
            Ext.apply(me, config);
            /**
             * @event statechange
             * Fires when a state change occurs.
             * @param {Provider} this This state provider
             * @param {String} key The state key which was changed
             * @param {String} value The encoded value for the state
             */
            me.addEvents("statechange");
            me.state = {};
            me.mixins.observable.constructor.call(me);
        },

        /**
         * Returns the current value for a key
         * @param {String} name The key name
         * @param {Mixed} defaultValue A default value to return if the key's value is not found
         * @return {Mixed} The state data
         */
        get : function(name, defaultValue){
            return typeof this.state[name] == "undefined" ?
                defaultValue : this.state[name];
        },

        /**
         * Clears a value from the state
         * @param {String} name The key name
         */
        clear : function(name){
            var me = this;
            delete me.state[name];
            me.fireEvent("statechange", me, name, null);
        },

        /**
         * Sets the value for a key
         * @param {String} name The key name
         * @param {Mixed} value The value to set
         */
        set : function(name, value){
            var me = this;
            me.state[name] = value;
            me.fireEvent("statechange", me, name, value);
        },

        /**
         * Decodes a string previously encoded with {@link #encodeValue}.
         * @param {String} value The value to decode
         * @return {Mixed} The decoded value
         */
        decodeValue : function(value){

            // a -> Array
            // n -> Number
            // d -> Date
            // b -> Boolean
            // s -> String
            // o -> Object
            // -> Empty (null)

            var me = this,
                re = /^(a|n|d|b|s|o|e)\:(.*)$/,
                matches = re.exec(unescape(value)),
                all,
                type,
                value,
                keyValue;

            if(!matches || !matches[1]){
                return; // non state
            }

            type = matches[1];
            value = matches[2];
            switch (type) {
                case 'e':
                    return null;
                case 'n':
                    return parseFloat(value);
                case 'd':
                    return new Date(Date.parse(value));
                case 'b':
                    return (value == '1');
                case 'a':
                    all = [];
                    if(value != ''){
                        Ext.each(value.split('^'), function(val){
                            all.push(me.decodeValue(val));
                        }, me);
                    }
                    return all;
               case 'o':
                    all = {};
                    if(value != ''){
                        Ext.each(value.split('^'), function(val){
                            keyValue = val.split('=');
                            all[keyValue[0]] = me.decodeValue(keyValue[1]);
                        }, me);
                    }
                    return all;
               default:
                    return value;
            }
        },

        /**
         * Encodes a value including type information.  Decode with {@link #decodeValue}.
         * @param {Mixed} value The value to encode
         * @return {String} The encoded value
         */
        encodeValue : function(value){
            var flat = '',
                i = 0,
                enc,
                len,
                key;

            if (value == null) {
                return 'e:1';
            } else if(typeof value == 'number') {
                enc = 'n:' + value;
            } else if(typeof value == 'boolean') {
                enc = 'b:' + (value ? '1' : '0');
            } else if(Ext.isDate(value)) {
                enc = 'd:' + value.toGMTString();
            } else if(Ext.isArray(value)) {
                for (len = value.length; i < len; i++) {
                    flat += this.encodeValue(value[i]);
                    if (i != len - 1) {
                        flat += '^';
                    }
                }
                enc = 'a:' + flat;
            } else if (typeof value == 'object') {
                for (key in value) {
                    if (typeof value[key] != 'function' && value[key] !== undefined) {
                        flat += key + '=' + this.encodeValue(value[key]) + '^';
                    }
                }
                enc = 'o:' + flat.substring(0, flat.length-1);
            } else {
                enc = 's:' + value;
            }
            return escape(enc);
        }
    });