    /**
     * @class Ext.util.Sorter
     * @extends Object
     * Represents a single sorter that can be applied to a Store
     */
    Ext.define('Ext.util.Sorter', {

        /**
         * @cfg {String} property The property to sort by. Required unless {@link #sorter} is provided
         */

        /**
         * @cfg {Function} sorterFn A specific sorter function to execute. Can be passed instead of {@link #property}
         */

        /**
         * @cfg {String} root Optional root property. This is mostly useful when sorting a Store, in which case we set the
         * root to 'data' to make the filter pull the {@link #property} out of the data object of each item
         */

        /**
         * @cfg {Function} transform A function that will be run on each value before
         * it is compared in the sorter. The function will receive a single argument,
         * the value.
         */

        /**
         * @cfg {String} direction The direction to sort by. Defaults to ASC
         */
        direction: "ASC",

        constructor: function(config) {
            var me = this;

            Ext.apply(me, config);

            //<debug>
            if (me.property == undefined && me.sorterFn == undefined) {
                Ext.Error.raise("A Sorter requires either a property or a sorter function");
            }
            //</debug>

            me.updateSortFunction();
        },

        /**
         * @private
         * Creates and returns a function which sorts an array by the given property and direction
         * @return {Function} A function which sorts by the property/direction combination provided
         */
        createSortFunction: function(sorterFn) {
            var me        = this,
                property  = me.property,
                direction = me.direction || "ASC",
                modifier  = direction.toUpperCase() == "DESC" ? -1 : 1;

            //create a comparison function. Takes 2 objects, returns 1 if object 1 is greater,
            //-1 if object 2 is greater or 0 if they are equal
            return function(o1, o2) {
                return modifier * sorterFn.call(me, o1, o2);
            };
        },

        /**
         * @private
         * Basic default sorter function that just compares the defined property of each object
         */
        defaultSorterFn: function(o1, o2) {
            var me = this,
                transform = me.transform,
                v1 = me.getRoot(o1)[me.property],
                v2 = me.getRoot(o2)[me.property];

            if (transform) {
                v1 = transform(v1);
                v2 = transform(v2);
            }

            return v1 > v2 ? 1 : (v1 < v2 ? -1 : 0);
        },

        /**
         * @private
         * Returns the root property of the given item, based on the configured {@link #root} property
         * @param {Object} item The item
         * @return {Object} The root property of the object
         */
        getRoot: function(item) {
            return this.root == undefined ? item : item[this.root];
        },

        // @TODO: Add docs for these three methods
        setDirection: function(direction) {
            var me = this;
            me.direction = direction;
            me.updateSortFunction();
        },

        toggle: function() {
            var me = this;
            me.direction = Ext.String.toggle(me.direction, "ASC", "DESC");
            me.updateSortFunction();
        },

        updateSortFunction: function() {
            var me = this;
            me.sort = me.createSortFunction(me.sorterFn || me.defaultSorterFn);
        }
    });