import java.io.*; import org.antlr.v4.runtime.*; public class SimpleMain { public static void main(final String[] args) throws IOException { String printSource = null, printSymTab = null, printIR = null, printAsm = null; SimpleLexer lexer = new SimpleLexer(new ANTLRInputStream(args[0])); SimpleParser parser = new SimpleParser(new CommonTokenStream(lexer)); String postfix = parser.program().s; System.out.println(postfix); } }