private DRLParser getParser(final InputStream is) {
try {
lexer = new DRLLexer( new ANTLRInputStream( is ) );
DRLParser parser = new DRLParser( new CommonTokenStream( lexer ) );
parser.setTreeAdaptor( new DroolsTreeAdaptor() );
return parser;
} catch ( final Exception e ) {
throw new RuntimeException( "Unable to parser Reader",
e );
}