* @param indexNode the index node whose column expression list is being processed (cannot be <code>null</code>)
*/
private void parseIndexColumnExpressionList( final String columnExpressionList,
final AstNode indexNode ) {
final DdlTokenStream tokens = new DdlTokenStream(columnExpressionList, DdlTokenStream.ddlTokenizer(false), false);
tokens.start();
tokens.consume(L_PAREN); // must have opening paren
int numLeft = 1;
int numRight = 0;