Bug 131011 Support running query based on report document data
Data Engine should support running a query based on data set and expression data stored in a report document. This bugzilla entry serves as a repository for design docs and notes related to this feature.
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/api/querydefn/BaseTransform.java
* The expression is evaluated after the last row in the series. A constant for the 
     * expressionTiming parameter of addExpression.  
     */
    public static final int AFTER_LAST_ROW 		= 1;
    /**
     * The expression is evaluated on each row. A constant for the 
     * expressionTiming parameter of addExpression.  
     */
    public static final int ON_EACH_ROW 		= 2;
    
    protected	List filters = new ArrayList();
    protected 	List subqueries = new ArrayList();
	protected 	List sorts = new ArrayList();
	protected 	List rowExpressions = new ArrayList();
	protected 	List beforeExpressions = new ArrayList();
	protected 	List afterExpressions = new ArrayList();
	
	private 	Map resultExprsMap = new HashMap( );
	
	/**
	 * Returns the filters defined in this transform, as an ordered list of 
	 * <code>IFilterDefintion</code> objects.
	 * 
	 * @return the filters. null if no filter is defined.
	 */
	public List getFilters( )
	{
		return filters;
	}
	/**