1. Save the JavaCC file as, say, hw1.jj
2. % javacc hw1.jj
3. % javac *.java
4. % java simple input_file_name

options {
  IGNORE_CASE = false;
  OPTIMIZE_TOKEN_MANAGER = true;
}

PARSER_BEGIN(simple)

import java.io.*;

public class simple {

  public static void main(String[] args) throws FileNotFoundException
  {
    if ( args.length < 1 ) {
       System.out.println("Input filename required as argument");
       System.exit(1);
    }
    
    SimpleCharStream stream = new SimpleCharStream(
				  new FileInputStream(args[0]));
    Token t = null;
    
    simpleTokenManager tokenMgr = new simpleTokenManager(stream);

     int line_no = 1;

    do {
        t = tokenMgr.getNextToken();

        switch(t.kind) {

         case ADD: System.out.println("ADD: " + t.image);
           break;
         case RELOP: System.out.println("RELOP: " + t.image);
           break;
         case NUMBER: System.out.println("NUMBER: " + t.image);
           break;
         case NAME: System.out.println("NAME: " + t.image + " line = " + line_no);
           break;
         case NL: line_no++;
           break;

         default:
           if ( t.kind != EOF )
             System.out.println("OTHER: " + t.image);
           break;
        }

    } while (t.kind != EOF);
  }
}

PARSER_END(simple)

SKIP:
{
  "\t"
| "\r"
| " "
}

TOKEN:
  {
    <NL: "\n">
  }

TOKEN: 
{
  <ADD: "+">
| <RELOP: "!=" | "==">
}

TOKEN: 
{
  <NUMBER: (["0"-"9"])+>
| <NAME: ["a"-"z","A"-"Z"] (["a"-"z","A"-"Z","0"-"9","_"])*>
}