Bug 145022 Provide a utility method to help GUI enhance aggregate on.
DtE will provide a method hasAggregation(String expression) in org.eclipse.birt.core.data.ExpressionUtil, and the return value will be true when the expression is a valid JS expression and it has aggregation defined.
core/org.eclipse.birt.core/src/org/eclipse/birt/core/data/ExpressionParserUtility.java
{
	private final String pluginId = "org.eclipse.birt.core";
	private final String ROW_INDICATOR = "row";
	private final String DATASETROW_INDICATOR = "dataSetRow";
	
	private static ExpressionParserUtility instance = new ExpressionParserUtility( );
	
	/**
	 * compile the expression
	 * 
	 * @param expression
	 * @return List contains all column reference
	 * @throws BirtException