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 void compileFunctionNode( FunctionNode node, ScriptOrFnNode tree,
			List columnExprList ) throws BirtException
	{
		compileComplexExpr( node, tree, columnExprList );
	}
	/**
	 * get the function node index
	 * 
	 * @param functionName
	 * @param tree
	 * @return
	 */
	private int getFunctionIndex( String functionName, ScriptOrFnNode tree )
	{
		int index = -1;
		for ( int i = 0; i < tree.getFunctionCount( ); i++ )
		{
			if ( tree.getFunctionNode( i )
					.getFunctionName( )
					.equals( functionName ) )
			{
				index = i;
				break;
			}
		}
		return index;
	}
}