/**
 * @class Ext.grid.RowNumberer
 * This is a utility class that can be passed into a {@link Ext.grid.ColumnModel} as a column config that provides
 * an automatic row numbering column.
 * 
Usage:

 

 // This is a typical column config with the first column providing row numbers
 var colModel = new Ext.grid.ColumnModel([
    new Ext.grid.RowNumberer(),
    {header: "Name", width: 80, sortable: true},
    {header: "Code", width: 50, sortable: true},
    {header: "Description", width: 200, sortable: true}
 ]);
 
 * @constructor
 * @param {Object} config The configuration options
 */
Ext.grid.RowNumberer = Ext.extend(Object, {
    
/**
     * @cfg {String} header Any valid text or HTML fragment to display in the header cell for the row
     * number column (defaults to '').
     */
    header: "",
    
/**
     * @cfg {Number} width The default width in pixels of the row number column (defaults to 23).
     */
    width: 23,
    
/**
     * @cfg {Boolean} sortable True if the row number column is sortable (defaults to false).
     * @hide
     */
    sortable: false,
    
    constructor : function(config){
        Ext.apply(this, config);
        if(this.rowspan){
            this.renderer = this.renderer.createDelegate(this);
        }
    },

    // private
    fixed:true,
    menuDisabled:true,
    dataIndex: '',
    id: 'numberer',
    rowspan: undefined,

    // private
    renderer : function(v, p, record, rowIndex){
        if(this.rowspan){
            p.cellAttr = 'rowspan="'+this.rowspan+'"';
        }
        return rowIndex+1;
    }
});