emptyContentCheck( localName, expression, parser );
FromDescr parent = (FromDescr) parser.getParent();
final CharStream charStream = new ANTLRStringStream( expression.trim() );
final DRLLexer lexer = new DRLLexer( charStream );
final TokenStream tokenStream = new CommonTokenStream( lexer );
final DRLParser drlParser = new DRLParser( tokenStream );
drlParser.setTreeAdaptor(new DroolsTreeAdaptor());
try {